United States 

Environmental Protection 

Agency 

Air and Radiation EPA420-R-02-016 

June 2002 

Highway Diesel 

Progress Review 

Printed on Recycled Paper 
EPA420-R-02-016 

June 2002 

Highway Diesel Progress Review 

Assessment and Standards Division 

Office of Transportation and Air Quality 

Office of Air and Radiation 

U.S. Environmental Protection Agency 

NOTICE 

This technical report does not necessarily represent final EPA decisions or positions. 

It is intended to present technical analysis of issues using data that are currently available. 

The purpose in the release of such reports is to facilitate the exchange of technical information 

and to inform the public of technical developments which may form the basis for a final EPA 

decision, position, or regulatory action. 
Executive Summary 

Executive Summary 

In December 2000, the U.S. Environmental Protection Agency (EPA or the Agency) 

finalized a comprehensive national emissions control program, the 2007 Highway Diesel (HD 

2007) program, that regulates highway heavy-duty vehicles and diesel fuel as a single system. 

Under the HD 2007 program, the Agency established new emission standards that will 

significantly reduce particulate matter (PM) and oxides of nitrogen (NOx). The monetized 

benefits of this program exceed its costs by a factor of nearly 17 to one. 

These PM and NOx engine standards reflect emission levels that are 90 percent and 95 

percent below the standards in effect today, respectively. They will begin to phase-in in model 

year 2007 (full compliance is not required until 2010) and will apply to heavy-duty highway 

engines and vehicles. These standards are based on the use of high-efficiency catalytic exhaust 

emission control devices or comparably effective technologies. The use of these technologies is 

enabled by a reduction of sulfur in highway diesel fuel by 97 percent, to 15 parts per million 

(ppm), by June 2006. 

While some industry stakeholders supported this program, other industry groups 

challenged specific provisions of the rulemaking in the United States Court of Appeals for the 

District of Columbia Circuit. After reviewing the arguments of the litigants and the substantial 

rulemaking record, on May 3, 2002, the District of Columbia Court of Appeals found for the 

Agency on all matters of substance. In particular, the Court found that the Agency’s conclusions 

regarding the level of sulfur in diesel fuel and the feasibility of advanced NOx and PM control 

technologies were reasonably determined and supported by the rulemaking record. 

Since December 2000, we have conducted a comprehensive progress review of the 

technologies needed to implement the program. This report documents the findings of our 

review. Specifically, this report provides our review of the progress of 1) manufacturers of diesel 

engines and emission control systems in developing technology to reduce engine exhaust 

pollutants, and 2) the petroleum refining industry in developing and demonstrating technologies to 

effectively lower the sulfur level of diesel fuel. Consistent with our stated intention in the HD 

2007 rulemaking, we are planning to continue monitoring, on an annual basis, industry’s progress 

in introducing technologies to meet the HD 2007 emission standards. 

To characterize the progress by the heavy-duty diesel engine industry (the engine 

manufacturers and the emission control technology manufacturers), we undertook a 

comprehensive company-by-company review. As part of this review, we visited technical 

research centers and met with engineers from more than twenty companies and received 

comprehensive high level briefings on technical progress and business plans to comply with the 

2007 emission standards. From these visits, we have been able to gauge industry progress to 

develop these technologies as well as industry plans and processes to meet the emission standards 

3

Highway Diesel Progress Review – June 2002 

for 2007. Although it is still early in the process, every major engine manufacturer that we visited 

told us that they expect to have emission-compliant products in 2007. 

We undertook a similar process to review diesel desulfurization technology progress. 

Specifically, this review involved company visits and conference calls, a review of information 

submitted through the program’s registration and reporting requirements, and a literature review. 

From the company meetings and reported information, we assessed progress in implementing 

diesel desulfurization technology as well as plans to produce 15 ppm diesel fuel. Our progress 

review shows that the technology needed to desulfurize diesel fuel to 15 ppm sulfur is well 

understood and will produce compliant fuel. While it is still early in the process given the 

2006-2010 window for compliance, the refining industry is where we anticipated it to be at this 

point in time. Moreover, some refining companies are ahead of schedule and will be capable of 

producing significant volumes of 15 ppm sulfur diesel fuel as early as next year. In fact, small 

amounts of 15 ppm sulfur diesel fuel are being produced today for use in retrofit and emission 

reduction programs in some metropolitan areas. 

Engine Technology Progress 

Catalyzed diesel particulate filters (CDPFs) were already well developed when we set the 

emissions standards for heavy duty vehicles that begin in 2007. As we discussed extensively in 

Chapter III of the Regulatory Impact Analysis (RIA) associated with the HD 2007 standards, 

CDPFs have been introduced in retrofit applications with great success where low sulfur diesel 

fuel is available. The CDPFs available at the time of the rulemaking provided dramatic emission 

reductions and good robustness for soot regeneration for most applications. Yet further 

improvements in CDPFs have continued including even better soot regeneration characteristics, 

better methods for dealing with oil ash, and reduced exhaust restrictions (reduced exhaust backpressure) while maintaining a high level of emission control effectiveness. 

We were pleased to observe during our progress review that industry has made 

improvements in the CDPF technology. CDPF catalyst systems have improved soot oxidation 

characteristics for passive filter regeneration. Total vehicle systems are being introduced that 

provide an active regeneration backup to ensure that under all driving conditions PM filters can 

regenerate. Every engine manufacturer that we visited was working on engine and emission 

control systems to ensure robust PM regeneration characteristics under all driving conditions. One 

manufacturer has even shown that the periodic NOx regeneration function necessary for proper 

NOx control can provide a synergistic improvement in PM soot regeneration. Based on the 

information shared by industry, we are more convinced than ever that, given low sulfur diesel fuel, 

CDPFs can be implemented with good soot regeneration characteristics on all heavy-duty diesel 

vehicles. In fact, one engine and vehicle manufacturer, International Truck and Engine Company, 

has already certified an engine with a CDPF that meets the HD 2007 emission standards for PM 

and hydrocarbons (HCs) for use in fleets where 15 ppm sulfur diesel fuel is already available. 

4

Executive Summary 

Although some application-specific technical challenges remain for CDPFs, all of the 

engine manufacturers expect and are planning to apply this technology fleet-wide by 2007. 

Furthermore, it is clear to us, as evidenced by International Truck and Engine Corporation’s 

Green Diesel Vehicles, that if low sulfur diesel fuel was broadly available prior to 2007, CDPFs 

could be introduced even sooner. 

NOx adsorbers were a less mature technology compared to CDPFs when we set the NOx 

emission standards for 2007. While NOx adsorbers had been applied successfully to light-duty 

lean-burn gasoline vehicles, additional development was still necessary to apply them to diesel 

vehicles. We identified areas requiring further development in Chapter III of the RIA for the HD 

2007 rulemaking and provided an analysis explaining how we expected the technology to improve 

to allow for its use for compliance with the HD 2007 NOx emission standard. Our review 

thoroughly investigated and examined what progress had occurred regarding the issues identified 

in the RIA. We were pleased to observe that significant progress has been made regarding each 

of the major issues confronting the NOx adsorber technology. 

One of the areas that we identified in the HD 2007 RIA as needing improvement for the 

NOx adsorber catalyst was performance at low and high temperatures. NOx adsorber 

performance is limited at very high temperatures (due to thermal release of NOx under lean 

conditions) and very low temperatures (due to poor catalytic activity for NO oxidation under lean 

conditions and low activity for NOx reduction under rich conditions) as described extensively in 

Chapter III of the HD 2007 RIA. We were pleased to discover during our review that significant 

progress has been made to broaden the temperature “window” (temperature range of effective 

NOx control) of the NOx adsorber catalysts. The catalyst development companies that we visited 

showed us a number of new catalyst formulations with improved performance. Similarly, many of 

the engine manufacturers we visited shared data with us that show the improvements in catalyst 

formulations corresponded to improvements in emission reductions over the regulated test cycles. 

It was clear from the data presented to us that the progress with regard to NOx adsorber 

performance was both substantial and broadly realized by most technology developers. 

Long term durability has been the greatest concern for the NOx adsorber catalyst as we 

explained in the HD 2007 RIA. We concluded in the RIA that, in order for NOx adsorbers to 

effectively control NOx emission throughout the life of a heavy-duty diesel engine, the fuel sulfur 

level would have to be maintained at or below 15 ppm, the NOx adsorber catalyst thermal 

durability needed to improve in order to allow for sulfur regeneration events, and system 

improvements would have to be made in order to allow for appropriate management of sulfur 

poisoning. It is in this area of durability that NOx adsorbers had the greatest need for 

improvement, and it is here where some of the most impressive strides in technology development 

have been made. During our review, we learned that catalyst companies are making significant 

improvements in the thermal durability of the catalyst materials used in NOx adsorbers. Similarly, 

the substrate manufacturers are developing new materials that do not react with the NOx storage 

materials (storage catalyst interaction with the catalyst substrate has been an important 

5

Highway Diesel Progress Review – June 2002 

degradation mechanism). The net gain from these simultaneous improvements is NOx adsorber 

catalysts which can be desulfated (go through a sulfur regeneration process) with significantly 

lower levels of thermal damage to the catalyst function. In addition, engine manufacturers and 

emission control technology vendors are developing new strategies to accomplish desulfation that 

allow for improved sulfur management while minimizing the damage due to sulfur poisoning. It 

was clear in our review that the total system improvements being made when coupled with 

changes to catalytic materials and catalyst substrates are delivering significantly improved catalyst 

durability to the NOx adsorber technology. 

Practical application of the NOx adsorber catalyst in a vehicle was a major concern of the 

industry during the HD 2007 rulemaking. Although there was considerable evidence that NOx 

adsorbers were highly effective and that durability issues could be addressed, some worried that 

the application of the NOx adsorber systems to vehicles would be impractical due to packaging 

constraints and the potential for high fuel consumption. Our review of progress has left us more 

certain than ever that practical system solutions can be applied to control emissions using NOx 

adsorbers. We have tested a diesel passenger car (one of the most difficult packaging situations) 

with a complete NOx adsorber and particulate filter system that demonstrated both exceptional 

emission control and good fuel economy. Heavy-duty engine manufacturers have shared with us 

their improvements in system design and means to regenerate NOx while minimizing fuel 

consumption. Similarly the various Department of Energy (DOE), Advanced Petroleum Based 

Fuel - Diesel Emission Control (APBF-DEC) program NOx adsorber projects are working to 

address the system integration challenges for a diesel passenger car, a large sport utility vehicle 

and a heavy heavy-duty truck. The challenge of full system design and implementation for the 

NOx adsorber catalyst remains but the number of entities working to resolve the issues and the 

substantial success to date suggests that these issues will be overcome. 

Over the last year and a half we met with a number of engine and vehicle manufacturers 

along with emission control system and component manufacturers in order to review progress to 

develop the NOx adsorber catalyst for introduction in 2007. In addition, we tested a NOx 

adsorber system on a heavy-duty diesel engine in our laboratory and tested a complete light-duty 

vehicle with a NOx adsorber system over the regulated emission cycles. Our review shows that 

the NOx adsorber catalyst and the associated system changes required to enable it are continuing 

to develop at a rapid pace. Given the short time window since December 2000, the substantial 

progress realized in that short time, and the relatively long lead time between now and 2007, and 

especially 2010, we believe that continued development of the technology will lead to its 

successful implementation. 

Diesel Desulfurization Technology Progress 

As discussed in the HD 2007 rule, conventional diesel desulfurization technologies have 

been available and in use for many years. We projected that all refiners would be technically 

capable of meeting the 15 ppm sulfur standard with extensions of the same conventional 

6

Executive Summary 

hydrotreating technology that they are using today to meet the current highway diesel fuel 

standard of 500 ppm sulfur. We also projected that all refiners would use recently developed, 

high activity catalysts, which increase the amount of sulfur that can be removed relative to the 

catalysts which were available when the current desulfurization units were designed and built 

more than 10 years ago. 

The information we have obtained to date from the discussions we had with technology 

vendors and refiners (since the final rule was promulgated) is consistent with the projections we 

made in the HD 2007 program – refiners are technically capable of producing 15 ppm sulfur diesel 

fuel using extensions of conventional technology and, in fact, they are moving forward with their 

plans to comply with the program. 

Refiners’ Plans for Producing 15 ppm Diesel Fuel 

We also reviewed the information submitted through the program’s registration and 

reporting requirements and met with a number of diesel fuel refiners to learn about their plans to 

produce 15 ppm diesel fuel by the June 2006 program compliance date. Since the 15 ppm diesel 

fuel sulfur standard was established based on the use of extensions of conventional diesel 

desulfurization technologies, diesel fuel refineries are well positioned to make firm plans for 

implementation by 2006. Our review has found that this is exactly what refiners are doing. We 

are very encouraged by the actions some refiners have already taken in terms of announcing 

specific plans for low sulfur diesel fuel production. It may still be early in the process, but 

virtually all refiners are already in the stage of planning their approach for compliance. Thus, the 

refining industry is where we anticipated it to be at this point in time. Moreover, some refining 

companies are ahead of schedule and will be capable of producing significant quantities of 15 ppm 

sulfur diesel fuel as early as next year. 

7

Highway Diesel Progress Review – June 2002 

8

Table of Contents 

Table of Contents 

Executive Summary .......................................................... 3


Table of Contents ........................................................... 9


List of Tables and Figures .................................................... 11


I. Introduction ......................................................... 13


II. Progress Review of Engine Technologies ................................... 17


A. Heavy Duty 2007 Standards ....................................... 17


B. Technology Status at the Time of the Rule ............................ 18


C. The Review Process ............................................. 20


1. Company Visits ........................................... 20


2.	 Testing at the National Vehicle and Fuel Emissions Laboratory (NVFEL)


....................................................... 21


3. Department of Energy (DOE) Research Programs ................. 21


D. Expectations for Progress and Industry Investment ...................... 22


E. PM Filter Progress .............................................. 24


1.	 Improvements in PM Filter Regeneration (Oxidation and Removal of


Stored Soot) ............................................. 24


2.	 Improvements in Ash Handling (Increased Service Interval Before Ash


Cleaning) ............................................... 26


3. Reductions in the Pressure Drop Across the PM Filter (Improved Fuel 

Economy) ............................................... 28


F. NOx Adsorber Progress .......................................... 29


1. Expanding the Temperature Window .......................... 30


2. Improvements in Thermal Durability ........................... 32


3. Methods and Performance for Desulfation (Sulfur Cleansing) ........ 36


4. Improvements in System Package Size and Integration ............. 40


G. Changes to Engine Oil Formulations ................................. 45


H. New Combustion Technologies .................................... 47


III. 	 Progress Review of Desulfurization Technology .............................. 49


A. Summary of the Highway Diesel Fuel Program Provisions ................ 49


1. Temporary Compliance Option ............................... 50


2. Hardship Provisions ....................................... 52


a. Small Refiner Hardship Provisions ....................... 52


b. GPA Refiner Provision ............................... 53


9

Highway Diesel Progress Review – June 2002 

c. General Hardship Provision ............................ 53


B. The Review Process ............................................. 54


1. Company Meetings and Visits ................................ 54


2. Information Obtained Through Reporting Requirements ............ 55


a. General Requirements ................................ 55


b. Small Refiners ...................................... 56


c. GPA Refiners ...................................... 57


3. Literature Review ......................................... 57


C. Desulfurization Technology Progress ................................ 58


1. Final Rule Estimates and Conclusions .......................... 58


2. Progress Since the Final Rule ................................ 59


a. Progress with Conventional Diesel Desulfurization Technology . 59


b. Other Issues ....................................... 62


3. Shared Desulfurization or Hydrogen Units ...................... 62


4. Emerging Technologies ..................................... 63


D. Refiners’ Plans for Producing 15 ppm Diesel Fuel ....................... 64


1. Steps in the Planning Process for Producing Low Sulfur Diesel ....... 65


a. Strategic Planning – Deciding What to do and When ......... 65


b. Planning & Front-end Engineering – Deciding How to Do it . . . 65


c. Detailed Engineering and Permits – Making the Arrangements . . 66


d. Procurement and Construction – Building It ............... 66


e. Commissioning and Startup – Making it Work .............. 67


2. Production Plans and Announcements .......................... 69


a. Public Announcements ............................... 70


b. Other Refiner Indications .............................. 71


c. Conversion of Off-highway to Highway Diesel Fuel Production . 72


d. Summary of Indicated Production Plans and Announcements . . . 72


e. U.S. Refinery Construction Projects ..................... 73


IV. Conclusions ......................................................... 77


Appendix A: List of Acronyms ................................................ 79


Appendix B: HD 2007 Progress Review Meetings ................................. 81


Appendix C: Literature Review ................................................ 83


References ................................................................ 85


10

Table of Contents 

List of Tables and Figures 

Table II.1 Emission Standards for Model Year 2007 and Beyond Heavy-Duty Engines. ..... 17


Table II.2 Toyota DPNR Vehicle Test Results at NVFEL ............................ 44


Table III.1 Industry Compliance Dates for the Highway Diesel Fuel Program. . . . 50


Table III.2 Intended Small Refiner Compliance Options by Number of Refineries ........... 71


Table III.3 Summary of Refinery Production Plans and Announcements .................. 73


Table III.4 Crude Expansion Projects at U.S. Refineries. ............................ 74


Table III.5 Hydrotreating and Hydrocracking Projects at U.S. Refineries. ............... 74


Table III.6 Hydrogen Plant Projects at U.S. Refineries. .............................. 75


Figure II.1 Improvements in NOx Adsorber Conversion Efficiency versus Temperature ..... 31


Figure II.2 Example NOx Adsorber Thermal Degradation ............................ 33


Figure II.3 Improvements in NOx Adsorber Thermal Durability with Cyclic Aging ......... 35


Figure II.4 Example of NOx Adsorber Desulfation ................................. 37


Figure II.5 NOx Adsorber Performance with Repeated Desulfation Events ............... 38


Figure II.6 Improvements in NOx Adsorber Durability with Repeated Desulfations ......... 39


Figure II.7 Improvements in Ability to Create Regeneration Conditions Engine-Out ........ 42


Figure II.8 Improvements in Fuel Consumption associated with NOx Regeneration ........ 42


Figure III.1 Map of the Credit Trading Regions Under the HD 2007 Program. ............ 51


Figure III.2 Geographic Phase-in Area .......................................... 53


Figure III.3 Low Sulfur Diesel Fuel Progress Timeline ............................... 69


11

Highway Diesel Progress Review – June 2002 

12

I. Introduction 

I. Introduction 

Background on the Highway Diesel Program 

In December 2000, the U.S. Environmental Protection Agency (EPA or the Agency) 

finalized a comprehensive national emissions control program, the 2007 Highway Diesel (HD 

a 2007) program, that regulates highway heavy-duty vehicles and diesel fuel as a single system. 

Under the HD 2007 program, the Agency established new emission standards that will 

significantly reduce particulate matter (PM) and oxides of nitrogen (NOx). The monetized 

benefits of this program exceed its costs by a factor of nearly 17 to one. 

These PM and NOx engine standards reflect emission levels that are 90 percent and 95 

percent below the standards in effect today, respectively. They will begin to phase-in in model 

year 2007 (full compliance is not required until 2010) and will apply to heavy-duty highway 

engines and vehicles. These standards are based on the use of high-efficiency catalytic exhaust 

emission control devices or comparably effective technologies. The use of these technologies is 

enabled by a reduction of sulfur in highway diesel fuel by 97 percent, to 15 parts per million 

(ppm), by June 2006. 

While some industry stakeholders supported this program, other industry groups 

challenged specific provisions of the rulemaking in the United States Court of Appeals for the 

District of Columbia Circuit. After reviewing the arguments of the litigants and the substantial 

rulemaking record, on May 3, 2002, the District of Columbia Court of Appeals found for the 

Agency on all matters of substance. In particular, the Court found that the Agency’s conclusions 

regarding the level of sulfur in diesel fuel and the feasibility of advanced NOx and PM control 

technologies were reasonably determined and supported by the rulemaking record. 

Final Rule Commitments and Implementation Activities 

This report summarizes several important steps that the Agency is taking in order to 

ensure a smooth implementation of the program. Specifically, the Agency is following through on 

actions to which it committed in the final rule and is pursing additional activities (as it has done 

historically) to assist regulated entities with program implementation and compliance. These 

commitments and activities are described in more detail below. 

In the preamble to the HD 2007 rule, the Agency committed to biennial assessments of the 

progress of NOx adsorber technology (66 FR 5063, January 18, 2001): 

a Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and 

Highway Diesel Fuel sulfur Control Requirements; Final Rule; 66 FR 5002, January 18, 2001 (signed December 

21, 2000). 

13 
Highway Diesel Progress Review – June 2002 

As a mechanism for monitoring and evaluating this technological progress, we 

believe it will be important to publicly reassess the status of heavy-duty diesel 

NOx adsorber systems on an ongoing basis. To accomplish this, we will conduct 

regular biennial reviews of the status of heavy-duty NOx adsorber technology...At 

the end of each review cycle, we will release (and post on the Web) a report 

discussing the status of the technology and any implications for the heavy-duty 

engine emission control program. We will release the first report by December 

31, 2002 and subsequent reports at the end of each second year through 

December 31, 2008. 

The HD 2007 rule also contains registration and reporting requirements for the petroleum 

industry which were designed to ensure a smooth transition to the program and to evaluate 

compliance once the program has begun. These reports will assist in educating the marketplace 

so that refiners can plan for compliance with more certainty regarding market conditions. 

Independent Review on Industry Progress 

In addition to the activities described above, the Agency announced its intention to 

establish an independent review panel to report on industry progress toward compliance with the 

program's requirements. Administrator Whitman described this independent review panel in a 

letter to Senator James Jeffords, Chairman of the Senate Committee on Environment and Public 

Works: 

...EPA will convene an outside panel of experts to independently assess the 

progress of: (1) manufacturers of diesel engines and emission control systems in 

developing technology to reduce engine exhaust pollutants; and (2) the fuels 

industry in developing and demonstrating technologies to effectively lower sulfur 

levels. The panel will be comprised of representatives of the major stakeholder 

b groups.... 

The Clean Diesel Independent Review Panel

c

 will operate under the auspices of the 

Federal Advisory Committee Act (FACA) as a Subcommittee of the Clean Air Act Advisory 

Committee. The panel is a temporary subcommittee (similar to the MTBE Blue Ribbon Panel 

which reviewed the use of methyl tertiary-butyl ether (MTBE) and other oxygenates in gasoline) 

which began its work in May and will conclude its work in September. As Administrator 

Whitman announced, the panel’s purpose is to review industry’s progress in implementing the 

program. Since the highway diesel program was only recently promulgated and the affected 

industries will have six to nine years lead time to meet the standards, we do not expect the panel 

b Letter from Administrator Whitman to Senator James Jeffords, September 27, 2001. 

c http://www.epa.gov/air/caaac/clean_diesel.html. 

14 
I. Introduction 

to find widespread adoption of technologies that meet the 2007 program requirements. Instead, 

the panel will focus on the development progress of applicable technologies, looking at 

information and activities since January 2001. 

The panel is composed of leading experts from the public health community, petroleum 

industry, engine manufacturing industry, exhaust emission control industry, and state 

governments. Daniel Greenbaum, President of the Health Effects Institute, will serve as the 

panel’s chairperson. Administrator Whitman has asked the panel to report its findings to her by 

mid-September 2002. 

As described above, EPA is also conducting a technical review, as part of the commitment 

it made in the final rule for an ongoing assessment of progress that industry is making toward the 

program's implementation. This report is our first biennial report and has been expanded to 

include the refinery industry technology progress. We will be providing this report to the Clean 

Diesel Independent Review Panel to bring all the participants up to date with our assessment of 

program implementation and to provide a starting point from which to conduct its review. 

Specifically, this report provides our review of the progress to date of 1) manufacturers of diesel 

engines and emission control systems in developing technology to reduce engine exhaust 

pollutants, and 2) the petroleum refining industry in developing and demonstrating technologies to 

effectively lower the sulfur level of diesel fuel to 15 ppm or less. 

15

Highway Diesel Progress Review – June 2002 

16

II. Progress Review of Engine Technologies 

II. Progress Review of Engine Technologies 

This section is organized chronologically to allow the reader to develop an understanding 

of the HD 2007 emissions program, the status of technology in December 2000, the process the 

EPA has gone through since the rulemaking to follow industry progress and finally a description 

of the progress that we have observed in our review. 

A. Heavy Duty 2007 Standards 

The highway diesel program contains a PM emissions standard for new heavy-duty 

engines of 0.01 grams per brake-horsepower-hour (g/bhp-hr), beginning with the 2007 model 

year. The program also establishes standards for NOx and non-methane hydrocarbons (NMHC) 

of 0.20 g/bhp-hr and 0.14g/bhp-hr, respectively. The NOx and NMHC standards will be phasedin together between 2007 and 2010, for diesel engines. The phase-in will be on a percent-of-sales 

basis: 50 percent from 2007 to 2009 and 100 percent in 2010. These standards are described in 

Table II.1, below. 

Table II.1 Emission Standards for Model Year 2007 and Beyond Heavy-Duty Engines. 

Standard 

(g/bhp-hr) 

Phase-In by Model Year 

2007 2008 2009 2010 

Diesel 

NOx 0.20 

50% 50% 50% 100 

NMHC 0.14 %

PM 0.01 100 

% 

100 

% 

100 

% 

100 

% 

The program includes flexibility provisions to facilitate the transition to the new standards 

and to encourage the early introduction of clean technologies, and adjustments to various testing 

and compliance requirements to address differences between the new technologies and existing 

engine-based technologies. 

EPA adopted a special provision for the Averaging, Banking, and Trading (ABT) 

program in the final rule that allows a manufacturer to create a single engine family meeting 

both the phase-out and phase-in standards during 2007-09 through averaging (see 40 CFR 

86.007-11(m)(9)). The manufacturer would split this family, declaring half of the engines in it 

to be “phase-out” engines, generating credits against the 2.5 g/bhp-hr NMHC+NOx standard, 

17

Highway Diesel Progress Review – June 2002 

and half to be “phase-in” engines, using these credits to demonstrate compliance with the 0.20 

NOx standard. A single set of Family Emission Limits (FELs) would be declared for both 

subfamilies, and no banked credits or credits from other engine families could be used, or viceversa. As a result, a manufacturer could, if desired, produce only engines meeting 

approximately a 1.2 g/hp-hr NOx FEL during the 2007-09 model years.d,e This corresponds to a 

roughly 50 percent NOx adsorber efficiency on a 2.5 g/hp-hr NOx+NMHC engine. None of 

these split family provisions affect the separate requirement to demonstrate compliance with the 

0.01 g/bhp-hr PM standard. 

This provision of the program means that for manufacturers choosing to do so, the 

program has a two-step NOx standard with an intermediate standard of 1.2 g/bhp-hr beginning in 

2007 that requires approximately a 50 percent reduction in NOx emissions. Full compliance 

with the 0.2 g/bhp-hr standard is then not required until 2010. This gives manufacturers 

substantially more flexibility in developing new technologies. 

B. Technology Status at the Time of the Rule 

In December 2000, we finalized a Regulatory Impact Analysis (RIA) that documented the 

technologies we expected would be used by industry to comply with NOx and Particulate Matter 

(PM) standards set in the associated HD 2007 rulemaking. The RIA detailed both the 

technologies we expected industry to use and particular challenges that industry would have to 

overcome in order to apply these technologies. In effect, the RIA laid out a path we thought it 

likely that the industry would follow in order to develop new technologies capable of meeting the 

HD 2007 emissions standards. While laying out a relatively well defined path for technology 

development, we also noted that technology developments are inherently difficult to predict and 

that, given the substantial lead time (six to nine years) available to develop technologies for 

compliance with the new emission standards, it would be appropriate for EPA to conduct biennial 

technology reviews. In particular, the preamble for the HD 2007 rule identified remaining 

technical issues with regard to the NOx adsorber technology that would need to be addressed. 

This report documents our findings in the first of these technology reviews. 

d The NOx FEL of the split family could vary somewhat depending on the NMHC emissions level, from 

1.16 for an engine emitting at the 0.14 g/bhp-hr NMHC standard, to 1.22 for an engine emitting no NMHC. This 

range is sufficiently narrow that, for the purposes of this technology review, it is sufficient to assume a 1.2 g/bhphr NOx level for any split family. 

e It should be noted too that this level is within the threshold values for application of the in-use add-on 

standards (1.3 g/bhp-hr NOx threshold-- see 40 CFR 86.007-11(h) ) and the 1.5x NTE NOx and NMHC 

multipliers (1.5 g/hp-hr NOx threshold-- see 40 CFR 86.007-11(a)(3) and (4)). 

18 
II. Progress Review of Engine Technologies 

The RIA identified some specific steps that we thought industry would take in order to 

commercialize the technology we thought most likely to be used to meet the NOx standard, the 

NOx adsorber catalyst. These steps, laid out in detail in Chapter III of the RIA, included: 

- Improvements to broaden the temperature range over which the NOx adsorber is 

effective (temperature window) 

- Improvements in thermal durability (resistance to thermal sintering) 

- Improvements in methods and performance for desulfation (sulfur cleansing) 

- Improvements in system integration (NOx regeneration, package, fuel economy) 

We focused on the need to make progress on these issues in conducting our review of technology 

developments reported here. The review process reveals, as detailed in the following sections, 

that industry has in fact made substantial progress toward addressing each of these issues. Even 

though a short amount of time has transpired since we finalized the HD 2007 rule, the results 

chronicled in this report show that the industry is well on its way to producing a NOx adsorber 

technology capable of meeting the HD 2007 NOx standards. 

While the PM filter technology was already well developed and in some cases 

commercially available at the time of the HD 2007 rulemaking, technology developers since that 

time have continued to improve the Catalyzed Diesel Particulate Filter (CDPF). Specific 

improvements in CDPFs include: 

- Improvements in PM filter regeneration (oxidation and removal of stored soot) 

- Improvements in ash handling (increase service interval before ash cleaning) 

- Reductions in the pressure drop across the PM filter (improved fuel economy) 

The CDPF technology has progressed such that where low sulfur diesel fuel is available (<15 ppm 

sulfur), one manufacturer is already selling vehicles with CDPFs that are in compliance with both 

the HC and PM standards set for 2007, a full five years before required. 

The RIA provided a much shorter analysis of the potential for future improvements in 

engine-out emissions. It noted that further modest emission reductions beyond the levels required 

by the emission standards for 2004 may be possible, but that significant reductions in NOx and 

PM would not be possible. While we continue to believe that catalyst based emission control 

technologies represent the only viable path for reducing NOx and PM emissions to levels 

substantially below the 2004 standards, we now also believe based on this review, that there are a 

number of in-cylinder emission control technologies which can provide valuable synergistic 

benefits in conjunction with catalyst based emission control technologies for compliance with the 

HD 2007 emission standards. These system solutions are limited to a relatively narrow range of 

engine operation but offer the potential to enhance the performance of both the NOx adsorber and 

CDPF technologies in order to improve the overall emission control performance of diesel engines 

across the broad range of engine operation. These new developments in in-cylinder emission 

19

Highway Diesel Progress Review – June 2002 

control and the synergies with NOx adsorbers and CDPFs further convinces us that a systems 

approach incorporating better engine management with the latest technologies and diesel fuel with 

a sulfur content below 15 ppm will allow engine manufacturers to meet these stringent new 

emission standards. 

C. The Review Process 

Our review of progress to develop technologies to meet the HD 2007 emission standards 

is based upon a broad spectrum of information provided by a cross-section of industry as well as 

government sources. We have aggregated some of the publicly available data in this report, but 

the conclusions we are drawing in this report are based upon both the publicly available 

information and the Confidential Business Information (CBI) that was shared with us during our 

meetings with industry. The following sections will detail how we conducted our progress 

review, and what we learned from that process. 

1. Company Visits 

We have conducted this progress review over the last year-and-a-half tracking 

developments by industry and by government / industry consortiums to develop technologies for 

heavy-duty diesel vehicles to meet the HD 2007 emission standards. We visited technical research 

centers and met with engineers from more than twenty companies and received comprehensive 

high level briefings on technical progress and business plans to comply with the HD 2007 

emission standards.f These visits included tours of research and development facilities, future 

manufacturing facilities for new diesel emission control equipment and detailed reviews of 

technology development and future planning. During each of these visits, we asked industry to 

estimate, based on each company’s experience, the current state of the NOx adsorber and CDPF 

technologies. We also asked the companies to review their plans and expectations to improve the 

technologies in the coming years. Finally, we asked the companies to provide us with detailed 

descriptions of their current and future investments in R&D and in new manufacturing that would 

be needed in order to bring the technologies to market by 2007. In composite then, we could 

evaluate the current status of the technologies, the expected performance of the technologies 

given further planned development and the level of financial commitment by each company to 

deliver a product by 2007. 

The information shared during these visits with the regulated industry provided the 

primary basis for our conclusions regarding progress by industry. Much of the information shared 

with EPA by industry was designated as Confidential Business Information (CBI) and as such can 

f Appendix B includes a list of the companies and organizations that we met with in conducting this 

review. 

20 
II. Progress Review of Engine Technologies 

not be described in detail here. This report attempts to provide a contemporaneous view of 

progress by industry as a whole using representative data from industry that has been released 

from designation as CBI. 

2.	 Testing at the National Vehicle and Fuel Emissions Laboratory 

(NVFEL) 

It is difficult to judge progress to develop new technologies without becoming first well 

familiar with the technologies and the challenges that must be overcome. EPA constituted a team 

of engineers and scientists at the National Vehicle and Fuel Emissions Laboratory (NVFEL) in 

1999 to begin work to evaluate and develop advanced diesel emission control technologies in 

support of the HD 2007 rulemaking. This team working with technical support from a number of 

emission technology and engine companies showed that NOx adsorber catalysts and diesel 

particulate filters can dramatically reduce diesel emissions. The work from that team, 

documented in detail in the HD 2007 RIA, provided a primary basis for our understanding of the 

technologies as we developed the HD 2007 emission standards. That team continued its work 

even after the rulemaking was completed in order to advance the state-of-the-art in emission 

control technologies and to inform this progress review. The experience gained by EPA staff in 

working on that team and the novel data gathered by the team helped inform our view of the 

current state-of-the-art of the NOx adsorber catalyst and the CDPF. Results from that work are 

documented throughout this report. 

3. Department of Energy (DOE) Research Programs 

The Department of Energy (DOE) along with a number of industry partners began a joint 

research program called the Diesel Emission Control Sulfur Effects (DECSE) program in 1998. 

The program evaluated the effect of sulfur in diesel fuel on the performance and durability of a 

number of diesel emission control technologies. The information from that program documented 

in five technical reports played an important role in informing the Agency during the HD 2007 

rulemaking.

1 Based on the success of the DECSE program, DOE along with a number of other 

government agencies including EPA, and an even larger group of industry supporters has begun a 

new research program entitled the Advanced Petroleum Based Fuels - Diesel Emission Control 

(APBF-DEC) program. The APBF-DEC program has separate research efforts focused on 

developing a NOx adsorber and CDPF based emission control system for a diesel passenger car, a 

sport utility vehicle, and a heavy heavy-duty engine. Although it is too early in the APBF-DEC 

program to have emission results from the systems, the work that has gone into designing the 

emission control systems for each of the applications has provided insight into how these 

technologies may be applied in the future. 

21

Highway Diesel Progress Review – June 2002 

The DOE has also sponsored a number of other research programs at National 

Laboratories and with industry to promote the development of advanced diesel engine systems. 

DOE has reviewed progress and results from these programs with EPA on an ongoing basis as the 

programs have developed new information. For this report, DOE provided a summary of the 

most significant research programs to EPA.

2 The DOE programs, similar to our own experience, 

show that NOx adsorbers offer the potential for large emission reductions and that significant 

progress is being made to improve their performance, but that technical issues remain to be 

addressed in the future. 

Our review of progress to develop technologies to meet the HD 2007 emission standards 

is based upon a broad spectrum of information provided by a cross section of industry as well as 

government sources. We have aggregated some of the publicly available data in this report, but 

the conclusions that we are drawing in this report are based upon both the publicly available 

information and the Confidential Business Information that was shared with us during our 

meetings with industry. 

D. Expectations for Progress and Industry Investment 

The regulations for heavy-duty diesel engines in 2007 were published less than 18 months 

ago and will not begin to go into effect for another five years and will not be fully phased-in until 

2010. Defining success for progress to meet emission standards with significant lead time 

remaining can be difficult. In this case, we were looking for two important aspects with regard to 

progress by industry to prepare for 2007. First, we looked to see that improvements were being 

made on the most important technical issues identified in the Regulatory Impact Analysis (RIA) 

(see Chapter III). Significant improvements in performance and durability have been made with 

regard to all of the technical issues identified in the RIA as detailed in Sections II.E and II.F of 

this report. 

The second important question that we looked to understand was whether financial 

investments and business plans were being made to deliver the technology by 2007. Absent 

significant investments by industry in research and development, in product planning and in 

manufacturing, a new technology can not be brought to market. As part of our progress review 

visits with industry we reviewed research plans, research spending levels, product plans and 

manufacturing investment in order to confirm that industry was making the appropriate 

commitments needed to deliver the clean diesel product for 2007. Our review found that industry 

is making substantial investments in research and development as well as for new manufacturing 

facilities in order to bring technologies to market for 2007. Although the manufacturers indicated 

that they are a number of years away from making their final technology selections for 2007, all 

had targeted plans showing how technology development and manufacturing would be integrated 

for 2007. No engine manufacturer indicated that they expected to be unable to develop a product 

22

II. Progress Review of Engine Technologies 

for 2007. Similarly, the engine manufacturers plans for compliance in 2010 were all designed to 

build upon their individual approaches for 2007. 

In order to provide information to the Agency on the degree of investment by industry to 

develop technologies for HD 2007 without revealing the confidential business plans of its 

members, the Manufacturers of Emission Control Association (MECA) surveyed it members and 

aggregated their responses regarding spending on research, development and capital 

improvements in order to develop new technologies for diesel engines. That data show that the 

MECA member companies will spend in excess of $1 billion cumulatively from 1999 to 2007 on 

diesel engine technologies (both for light and heavy duty diesel vehicles). This represents a 

substantial investment by the industry to develop new technologies and to put manufacturing 

systems in place to produce advanced emission control systems. A number of companies 

emphasized in their survey responses that these investments are being premised on the knowledge 

that these technologies will be needed and available for 2007. The fact that such significant 

investments are being made shows that this industry has high confidence that the technology will 

be ready for production by 2007. 

Although, final technology decisions have not been made by any of the engine 

manufacturers, most indicated that they intend to make use of a flexibility in the HD 2007 rule 

allowing manufacturers to certify to an average NOx standard of approximately 1.2 g/bhp-hr in 

2007. The manufacturers that are planning to follow this path indicated that they are expecting to 

use NOx aftertreatment technologies to comply with the effective average standard. None of the 

manufacturers felt that they would have an engine-out emission control technology capable of 

meeting the NOx and PM standards. Nor did any manufacturer believe that they could develop a 

sulfur insensitive technology to comply in 2007. Manufacturers gave a number of reasons for 

following this path: 

- simpler to apply and market a single technology across all engines 

- provides additional “headroom” below the standard for catalyst deterioration 

- allows for orderly progress of technology toward full compliance in 2010. 

In summary, then, based on our review of manufacturers plans and successes to date, we 

are left well convinced that industry is making the appropriate financial investments and prudent 

planning to deliver compliant technology for 2007 and for 2010. In fact, the investments that 

industry is making are so large that serious financial hardship could be incurred were changes to 

the program considered that would, in effect, delay the implementation of the new technologies. 

These significant investments are paying substantial dividends in technology advancements as 

detailed in the following sections. 

23

Highway Diesel Progress Review – June 2002 

E. PM Filter Progress 

We identified the Catalyzed Diesel Particulate Filter (CDPF) as the technology most likely 

to be adopted by industry in order to comply with the 0.01 g/bhp-hr particulate matter (PM) 

standard set for heavy-duty diesel vehicles beginning in 2007. The technology is highly effective 

at controlling PM when used with low sulfur diesel fuel as described in detail in Chapter III of the 

HD 2007 RIA. The technology has proven itself in tens of thousands of retrofit applications 

where low sulfur diesel fuel is already available. Yet, there are some aspects of the catalyzed 

diesel particulate filter which we believe will be improved before 2007. 

This section details specific areas where we have observed further improvements in the 

CDPF technology. 

1.	 Improvements in PM Filter Regeneration (Oxidation and Removal 

of Stored Soot) 

CDPFs control diesel PM by capturing the soot (solid carbon) portion of PM in a filter 

media, typically a ceramic wall flow substrate, and then by oxidizing (burning) it in the 

oxygen-rich atmosphere of diesel exhaust.

g In aggregate over a driving cycle, the PM must be 

burned at a rate equal to or greater that its accumulation rate, or the CDPF will clog. Given low 

sulfur diesel fuel (diesel fuel with a sulfur content of 15 ppm or lower), highly active catalytic 

metals (e.g., platinum) can be used to promote soot oxidation. This is the primary means of soot 

oxidation that we projected industry would use in 2007. 

During our review of technology developments for 2007, we learned that additional 

progress is being made both to improve catalytic-based soot regeneration technologies and to 

develop system solutions to ensure that even under the most extreme conditions soot regeneration 

can be assured. Improvements in catalytic soot oxidation are important because more active soot 

oxidation can help to improve fuel economy and to ensure robust soot regeneration. A PM filter 

with a more effective soot oxidation catalyst would be expected to have a lower average soot 

loading and therefore would be less restrictive to exhaust flow, thus decreasing the pressure drop 

across the PM filter and leading to better fuel economy. Additionally, improved soot oxidation 

effectiveness will provide additional assurance that excessive soot loading which could lead to PM 

filter failure will not occur. 

g The gas phase hydrocarbons that make up the soluble organic fraction (SOF) of PM are controlled with 

CDPFs through oxidation of the SOF on the catalyst. The CDPF does not control the sulfate fraction of PM, and in 

fact, can increase the sulfate fraction due to the oxidation of sulfur species on the catalyst. See Chapter III of the 

HD 2007 RIA for a more complete description of CDPFs. 

24 
II. Progress Review of Engine Technologies 

At a recent conference of the Society of Automotive Engineers (SAE) a paper was 

presented that documented improvements in catalyzed diesel particulate filter system design in 

order to improve soot oxidation effectiveness. The paper showed that changes in where catalytic 

materials were coated within a PM filter system (on an up-front flow through catalyst, on the 

surface of the PM filter or a combination of both) influenced the effectiveness of the catalyst 

material to promote soot oxidation.

3 This kind of system analysis suggests that there remains 

opportunities to further improve how diesel particulate filters are designed to promote soot 

oxidation and that different solutions may be chosen dependent upon expected vehicle operation 

(expected exhaust temperature history), packaging constraints and cost. The fact that there 

continues to be system enhancements of the relatively mature diesel particulate filter technology 

gives us great confidence that PM filters can be applied broadly in 2007. 

Although highly effective catalytic soot oxidation, enabled by clean diesel fuel (15 ppm S), 

suggests that PM filters will regenerate passively for most vehicle applications, there remains the 

possibility that for some conditions active regeneration systems (backup systems) may be 

desirable. This is perhaps most likely for vehicles which are operated primarily as passenger 

vehicles (light duty cars and trucks, and some light heavy-duty trucks). For this reason a number 

of vehicle manufacturers have developed systems to help ensure that PM soot regeneration can 

occur under all conditions. One example of this is a current production product sold in Europe by 

PSA/Peugeot. On diesel powered Peugeot passenger cars a PM filter system is installed that 

includes mechanisms for engine-promoted soot oxidation.

h The vehicle estimates soot loading 

from a number of parameters including exhaust backpressure and can periodically promote more 

rapid soot oxidation by injecting additional fuel late in the combustion cycle. This fuel is injected 

so late in the cycle that it does not contribute to engine power but instead is combusted (oxidized) 

across an oxidation catalyst in front of the PM filter. The combustion of the fuel across the 

catalyst increases the exhaust temperature substantially promoting rapid soot oxidation. By the 

end of 2002, Peugeot expects to have 270,000 passenger cars with this technology on the road.4 

Other vehicle manufacturers indicated to EPA during our progress review, that they intend to 

introduce similar technologies in the near future.

i They noted that this was not driven by 

regulation but by customer demand for clean diesel technologies. The fact that manufacturers are 

introducing PM filter technologies in advance of mandatory regulations suggests that the 

technology is well developed and mature. 

The potential for synergistic benefits to the application of both PM filters and NOx 

adsorbers was highlighted by EPA in the HD 2007 rulemaking but at that time little was known as 

h The PSA system also uses a cerium fuel additive to promote soot oxidation. However, the exhaust 

temperature is often still too low for adequate soot oxidation necessitating an active regeneration strategy. 

i One important difference between these new systems and the PSA system is the use of a fuel additive to 

promote soot oxidation. While the current PSA system uses a cerium fuel additive, future systems from other 

manufacturers are not expected to use a fuel additive. 

25 
Highway Diesel Progress Review – June 2002 

to the extent of these synergistic benefits. Toyota has developed a combined diesel particulate 

filter and NOx adsorber technology dubbed DPNR (Diesel Particulate NOx Reduction). The 

mechanism for synergistic PM soot regeneration with programmed NOx regeneration was 

recently documented by Toyota in a SAE publication. The paper showed that active oxygen 

molecules created both under lean conditions as part of the NOx storage function and under rich 

conditions created by the NOx regeneration function were effective at promoting soot oxidation 

at low temperatures.5 This suggests that the combination of a NOx adsorber catalyst function 

with a diesel particulate filter can provide a more robust soot regeneration system than a PM 

filter-only technology. This benefit may be one consideration for engine manufacturers who 

choose to apply the NOx adsorber technology across all of their product lines in 2007 as allowed 

for in the ABT program. Most catalyst development companies that we visited with indicated 

that they are presently developing similar technologies and at least one has announced that they 

will have a product available by 2007.j 

Soot regeneration under all possible vehicle operating conditions is the most important 

issue for the PM filter technology. Failure of the system to regenerate can lead to unacceptable 

vehicle operation and excessive fuel consumption. We believed, as explained in Chapter III of the 

HD 2007 RIA, that the PM filter systems had advanced to the point that regeneration under all 

conditions could be ensured. Given the further improvements in the technology, and the fact that 

PM filters are already being applied by vehicle manufacturers in what are perhaps the most 

difficult applications (passenger car driving cycles), makes us even more confident that this 

technology is appropriate for widespread vehicle application. Significantly, all engine 

manufacturers have indicated to us that they intend to use PM filters in order to comply with the 

HD 2007 emission standards. We believe that the only thing preventing the opportunity for 

widespread use of PM filters today is the limited availability of clean diesel fuel (15 ppm sulfur 

fuel). In areas of the country where low sulfur diesel fuel is available early introductions of the 

technology are in fact occurring today a full five years before the emission standards go into 

effect. 

2. Improvements in Ash Handling (Increased Service Interval Before 

Ash Cleaning) 

Inorganic solid particles present in diesel exhaust can be captured by diesel particulate 

filters. Typically these inorganic materials are metals derived from engine oil, diesel fuel or even 

engine wear. Without a PM filter these materials are normally exhausted from the engine as diesel 

PM. While the PM filter is effective at capturing inorganic materials it is not typically effective at 

removing them, since they do not tend to be oxidized into a gaseous state (carbon soot is oxidized 

to CO2 which can easily pass through the PM filter walls). Because these inorganic materials are 

j Johnson Matthey has recently announced that they will sell an integrated NOx adsorber PM filter 

technology dubbed Total Catalytic Reduction Technology or TCRT. 

26 
II. Progress Review of Engine Technologies 

not typically combusted and remain after the bulk of the PM is oxidized from the filter they are 

typically referred to as ash. While filtering metallic ash from the exhaust is an environmental 

benefit of the PM filter technology it also creates a maintenance need for the PM filter in order to 

remove the ash from the filter. 

The maintenance function for the removal of ash is relatively straightforward, and itself 

does not present a significant technical challenge for the industry. However, both the industry and 

EPA would like to see ash related PM filter maintenance reduced as much as possible if not 

eliminated. EPA has specific guidelines for acceptable maintenance intervals intended to ensure 

robust emission control technologies (100,000 mile minimum intervals for light heavy-duty trucks 

and 150,000 miles for medium and heavy heavy-duty trucks). Engine manufacturers are similarly 

motivated to improve reliability and reduce maintenance to minimize end-user costs. The issue of 

ash accumulation was raised consistently during our progress review visits with the industry. The 

industry is investigating a number of ways to address this issue including means to improve ash 

tolerance and to reduce the amount of ash present in diesel exhaust. 

For most current PM filter designs ash accumulates at the end of the inlet passages of the 

PM filter. As more ash is accumulated, the effective filter size is reduced because the ash fills the 

end of the passage shortening the effective filter length. One simple approach to address ash is to 

increase PM filter size in order to tolerate higher levels of ash accumulation. This approach, 

although effective, is undesirable due to the added cost and size of the resulting PM filter. A 

number of companies are investigating means to develop PM filter mechanisms which are more 

ash tolerant. These approaches include concepts to increase storage area within the filter itself 

and concepts which promote self-cleaning of the filter perhaps driven by engine and vehicle 

vibrations during normal vehicle operation. It was not clear during our review that these 

technologies would be able to fully address ash accumulation, but they were indicative of the 

potential to increase the interval between necessary ash removal maintenance activities. 

In addition to concepts to improve ash handling, possibilities exist to decrease the amount 

of ash present in diesel exhaust. The predominant source of ash in diesel exhaust is inorganic 

materials contained in engine oil (oil ash). A significant fraction of the ash in engine oil is from 

additives necessary to control acidification of engine oil due in part to sulfuric acid derived from 

sulfur in diesel fuel. As the sulfur content of diesel fuel is decreased, the need for acid neutralizing 

additives in engine oil should also decrease. The concept of an engine oil with less ash content is 

often referred to as “low-ash oil.” A number of technical programs are ongoing to determine the 

impact of changes in oil ash content and other characteristics of engine oil on exhaust emission 

control technologies and engine wear and performance. Historically, as engine technologies have 

changed (often due to changes in emission regulations) engine oil formulations have also changed. 

These changes have been accomplished through industry consensus on oil specifications based on 

defined test protocols. This process of consensus definition has begun for 2007, and we have 

every confidence that as in the past, this process will succeed in delivering new oil formulations 

27

Highway Diesel Progress Review – June 2002 

appropriate for 2007 engine technologies. A more complete description of industry programs to 

define a new engine oil for 2007 is presented in Section II.G below. 

It may also be possible to reduce the ash level in diesel exhaust by reducing oil 

consumption from diesel engines. Diesel engine manufacturers over the years have reduced 

engine oil consumption in order to reduce PM emissions and to reduce operating costs for vehicle 

owners. Further improvements in oil consumption may be possible in order to reduce ash 

accumulation rates in PM filters. If oil accumulation rates could be halved and engine oil ash 

content similarly decreased, the PM filter maintenance interval would be increased fourfold. 

Current retrofit PM filter ash maintenance intervals can range from 60k miles to more than 125k 

miles.

6 The HD 2007 RIA estimated that PM filter maintenance for ash accumulation would 

occur at 150k mile intervals. Progress by industry to decrease oil ash maintenance would 

suggests that this interval is conservatively short and actual maintenance intervals for 2007 will be 

longer. 

3.	 Reductions in the Pressure Drop Across the PM Filter (Improved 

Fuel Economy) 

The most common type of PM filter is a wall flow ceramic filter made of either cordierite 

or silicon carbide. The filter consists of a honeycomb ceramic similar to the ubiquitous flowthrough catalyst substrate used on almost all passenger cars today but with alternately plugged 

channels such that no flow-through channel exists. Instead, gases enter an open channel and must 

diffuse through the wall of the filter into an adjacent channel which is open to the exit of the filter. 

The wall between the adjacent inlet and outlet channels serves as the filtering media. The pressure 

drop (essentially the pumping work) across the PM filter is determined by flow losses in the inlet 

and exit channels and the flow loss through the filter wall. There are a number of filter design 

parameters that engineers can change in order to reduce the flow restriction of the PM filter. 

Recent work by several PM filter manufacturers shows that PM filter designs can be improved to 

reduce the pressure drop across the PM filter (improve fuel economy) without necessarily 

adversely impacting filtering efficiency. 

In a paper entitled SiC (silicon carbide) and Cordierite Diesel Particulate Filters 

Designed for Low Pressure Drop and Catalyzed, Uncatalyzed Systems researchers at NGK 

Insulators documented their work to define the controlling characteristics of PM filter efficiency 

and pressure drop.

7 The researchers investigated the effects of changes to filter porosity, mean 

pore size, cell density, and wall thickness to determine differences in the observed pressure drop 

between various combinations of design changes. They used both modeling results and 

experimentation to identify the key parameters affecting flow restriction through the PM filter. 

The results showed that flow characteristics changed significantly between a clean PM filter (no 

soot loading) and one with a developed layer of soot. Once a filter has developed a layer of 

filtered soot, their research showed that flow losses through the filter wall dominated the observed 

28

II. Progress Review of Engine Technologies 

pressure drop. The modeling and experimental results suggest that high cell density (more narrow 

channels in a given area) will lead to reduced pressure-drop due to the increase in filter area (total 

wall area) up to a point, when the channel flow losses begin to dominate. The researchers 

concluded that a cell density of 300 cells per square inch represents an optimal cell density. 

Similarly, they showed that high porosity and large pores reduce the pressure drop observed with 

soot loading. However, this reduction in flow losses comes with a reduction in PM filtering 

efficiency. The researchers concluded that an optimal uncoated filter design will have a porosity 

within a range from 10 micron to 70 micron. The research described primarily the performance of 

uncatalyzed soot filters, future work by the researchers will investigate the performance and 

pressure drop for soot filters with a catalytic coating. The addition of a catalytic coating was 

shown to change the pressure drop characteristics dramatically. The mean pore diameter and the 

distribution of pore sizes are expected to be critical design elements relating to coated PM filter 

designs. 

In our meetings with PM filter manufacturers, we learned that similar internal studies are 

being made by a number of researchers. The companies have made significant research 

investments to apply science to design PM filter materials. These investments have resulted in a 

dramatic improvement in the understanding of the various design parameters that are critical to 

PM filter design. Based on this improved science, future PM filter designs are expected to offer 

better tradeoffs between pressure drop (fuel economy) and filtering efficiency.

k 

F. NOx Adsorber Progress 

NOx adsorbers work to control NOx emissions by storing NOx on the surface of the 

catalyst during the lean engine operation typical of diesel engines and then by undergoing 

subsequent brief rich regeneration events where the NOx is released and reduced across precious 

metal catalysts. This method for NOx control has been shown to be highly effective when applied 

to diesel engines but has a number of technical challenges associated with it. In the HD 2007 RIA 

we identified four primary issues related to: performance of the catalyst across a broad range of 

exhaust temperatures, thermal durability of the catalyst when desulfated, management of sulfur 

poisoning and system integration on a vehicle. Over the last 18 months we have conducted a 

review of progress by industry and various government entities to address these technical 

challenges. This section describes what we have learned with regard to each of these issues. 

k It should be noted that the fuel economy impact of even today’s PM filter technology is quite small if not 

negligible. Tests of PM filter equipped diesel vehicles are often unable to determine the impact of the PM filter on 

fuel consumption because the change in fuel consumption is smaller than the variation in the fuel consumption 

measurement accuracy. 

29 
Highway Diesel Progress Review – June 2002 

1. Expanding the Temperature Window 

NOx adsorber performance is limited at low temperatures (due to poor catalytic activity 

for NO oxidation under lean conditions and low activity for NOx reduction under rich conditions) 

and at high temperatures (due to thermal release of NOx under lean conditions). There is an 

extensive discussion in Chapter III of the HD 2007 RIA describing these issues. This section of 

the report documents some of the progress to address these issues. 

We visited a number of catalyst development companies during this progress review and 

asked them to describe and characterize progress in improving NOx adsorber performance since 

the HD 2007 rulemaking was completed. Figure II.1 below shows data provided by a major 

catalyst development and manufacturing company characterizing improvements that they have 

made in NOx adsorber performance since that time. The figure shows that substantial 

improvements have been made in low temperature NOx adsorber performance. NOx conversion 

efficiencies at 200� C have improved from approximately 10-30 percent to greater than 70 percent 

(compare curves B and D, representing catalyst formulations from 2000, with curves A and C 

representing catalyst formulations from 2001). 

30

200 250 300 350 400 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

NO 

x Conv

ersion (% ) 

Te m p erature (oC) 

II. Progress Review of Engine Technologies 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

200 250 300 350 400 

Cat A was developed in 2001. 

Cat B was developed in 2000. 

Cat C was developed in 2001. 

Cat D was developed in 2000. 

C ata lyst A 

C ata lyst B 

C ata lyst C 

C ata lyst D 

Cat A was developed in 2001. 

Cat B was developed in 2000. 

Cat C was developed in 2001. 

Cat D was developed in 2000. 

Tem perature (oC) 

Figure II.1 Improvements in NOx Adsorber Conversion Efficiency versus Temperature 

Similar improvements in NOx adsorber efficiency across a broad temperature range were 

reported by almost all of the catalyst manufacturers that we visited during our progress review. 

Although the improvements as shown in Figure II.1 are significant, further enhancements in NOx 

adsorber efficiency may yet be possible. A recent publication by researchers from Toyota 

documents a newly developed NOx adsorber catalyst technology that shows a dramatic increase 

in NOx storage capacity (more than two-fold) at high temperatures while reducing slightly the 

amount of sulfur stored (reducing sulfur poisoning).

8 This technology enhancement may allow for 

improvements not only in storage capacity but also in high temperature NOx adsorber 

performance for diesel engines, since NOx storage capacity at temperatures above 500� C are 

related to the decrease in NOx adsorber efficiency observed there. 

It was known at the time of the HD 2007 rulemaking that different NOx storage 

compounds could be selected in order to improve high temperature NOx storage function.

9 What 

was less well understood was how durable NOx adsorber technologies would be that relied on 

these high temperature storage elements. Since the rulemaking considerable work has been done 

to better understand this aspect of the NOx adsorber technology and to develop new catalyst 

formulations that take advantage of the high temperature storage function while maintaining NO

x Conv

ersion (

%) 

31

Highway Diesel Progress Review – June 2002 

acceptable durability. A recent publication by Danan Dou and Jean Balland of Delphi Automotive 

Systems documents some of this work.

10 Their research shows that the addition of alkali earth 

metals to barium based NOx adsorber catalysts dramatically improves high temperature NOx 

adsorber performance when compared to a barium only formulation. While this relationship to 

high temperature performance was known previously, the authors also showed that this improved 

performance (compared to the barium only case) held true even after high temperature aging and 

after repeated sulfur poisoning and desulfation events. These improvements when coupled with 

improvements in catalyst substrate materials (discussed in Section II.F.2 below) mean that NOx 

adsorber performance at high temperature can be improved without unacceptably harming long 

term durability. This improved understanding represents significant progress in the development 

of NOx adsorber catalysts for diesel engines operated under high load and for gasoline engines. 

Further improvements in NOx adsorber reduction efficiency across the temperature range 

of a diesel engine may yet be possible. Also as discussed in Section II.H below, new combustion 

technologies may offer a means to raise diesel exhaust temperatures at low load conditions 

enhancing the performance of the NOx adsorber catalyst system. Our review of progress by 

industry to improve the match between the operating temperature window of the NOx adsorber 

catalyst and the operating range of diesel engines leads us to continue to believe that the NOx 

adsorbers systems that will be available in 2007 will be highly effective across the broad range of 

diesel engine operation. 

2. Improvements in Thermal Durability 

Long term durability for the NOx adsorber catalyst was another issue that we outlined in 

the HD 2007 RIA. Heavy-duty diesel vehicles are extremely durable, lasting for hundreds of 

thousands of miles. In order to realize significant emission reductions, emission control 

technologies must be similarly durable. NOx adsorbers are poisoned by sulfur in diesel fuel and 

the means to recover the performance loss from poisoning can damage the NOx adsorber 

thermally as explained in Chapter III of the HD 2007 RIA. Our concern regarding NOx adsorber 

durability was one of the primary reasons for controlling sulfur in diesel fuel to 15 ppm. 

However, even with 15 ppm sulfur fuel NOx adsorber catalysts must be periodically desulfated, a 

process which can itself damage the NOx adsorber catalyst due to the high temperatures (>650C) 

required for desulfation.

11 Our progress review has therefore focused on what progress has been 

made to improve the thermal durability of the NOx adsorber catalyst, especially with regard to the 

periodic high temperature excursions experienced during desulfation. 

At the National Vehicle and Fuel Emissions Laboratory (NVFEL) in Ann Arbor, Michigan 

a team of EPA engineers and scientists has been working to characterize various aspects of NOx 

adsorber thermal aging. In order to do that the team first investigated the temperature mechanism 

by aging the adsorbers with zero sulfur fuel and low sulfur engine oil (750 ppm) at high engine 

operating temperatures (510 C). Figure II.2 below shows results from some of this testing on 

two different NOx adsorber formulations (from two different catalyst manufacturers). The graph 

32

II. Progress Review of Engine Technologies 

shows that both NOx adsorber formulations deteriorated from their fresh condition. The degree 

of deterioration is exaggerated in the figure by showing the difference at the highest temperature 

mode (where the degradation is the largest) in order to highlight differences between catalyst 

technologies. The results have shown that changes in NOx adsorber formulation (presumably 

somewhat different technologies) give different performance with thermal aging. The results 

suggest that even at exhaust temperatures which are at the high end of normal operation, 

differences in NOx adsorber formulations can lead to improvements in aged performance. 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

Adsorber 0 Adsorber 1 

0 Hours 

100 Hours 

Figure II.2 Example NOx Adsorber Thermal Degradation 

These results have been shared with the catalyst manufacturers that are supporting the test 

programs. Based on information from these results, catalyst manufacturers are developing new 

catalysts to address the issues highlighted here. The team is continuing its investigations and will 

add periodic desulfation temperature excursions (600-700� C) to investigate what impact the 

higher temperatures will have on the adsorber aging. Finally, sulfur will be added to the fuel to 

investigate the combined temperature and sulfur impacts on adsorber aging. 

One of the pieces of information that we considered in the HD 2007 RIA was the loss in 

NOx adsorber performance experienced in the DECSE program when the NOx adsorber catalyst 

in that program was subjected to repeated desulfation events.(DECSE)

12 The high rate of NOx 

aging observed in the DECSE study was contrasted with the very good NOx adsorber NOx Reduction (%) 

33

Highway Diesel Progress Review – June 2002 

performance noted in the work by Dearth, et al. at Ford’s Scientific Research Laboratory also 

referenced in RIA.

13 Under what appear to have been similar test conditions of repeated lean/rich 

cycling at elevated temperatures (both near 700� C) one catalyst showed exceptionally good 

recovery of NOx adsorber performance (the Ford study), while the other catalyst exhibited a 

gradual but substantial loss in NOx adsorber performance, even when the lean / rich cycling was 

done in the absence of sulfur.

14 At the time, we believed that the observed differences in catalyst 

performance were related to differences in the catalyst formulation and the selection of the 

appropriate temperature for desulfation (i.e., we believed 700� C was too hot for the DECSE 

catalyst formulation). Data shared with us as part of this progress review by a major catalyst 

developer and manufacturer suggests that this assessment was accurate but incomplete. Their 

testing shows that the history of lean/rich cycling of the catalyst at elevated temperature is also an 

important factor in NOx adsorber deterioration. These results are explained below. 

New test data from a major catalyst development company was shared with EPA as part 

of this technical review. The data shows thermal testing of a candidate 2000MY NOx adsorber 

catalyst carried out by subjecting the catalyst to 700� C temperature under lean conditions for 16 

hours (the diamond solid line in Figure II.3 below). The results from that testing were very 

encouraging showing high NOx conversion efficiency even after the lean aging period. 

Subsequent testing of the catalyst however showed an unexpected decrease in performance over 

time. Because of this loss in performance, the catalyst manufacturer designed a new test to verify 

the thermal aging characteristics of the catalyst when aged at the same temperature but with 

periodic lean/rich transitions. The results of that testing for the 2000MY NOx adsorber catalyst 

formulation are shown as the open diamond dashed line in Figure II.3 below. It can be seen from 

the figure that the aged performance under lean/rich cycling conditions (similar to those 

experienced in the desulfation portion of the DECSE study) resulted in a significant loss in NOx 

adsorber performance. The loss in NOx performance shown here is roughly equivalent to the loss 

in performance observed in the DECSE program discussed in the HD 2007 RIA. 

34

II. Progress Review of Engine Technologies 

100


90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

2000MY, Lean Aged 

2000MY, Cyclic Aged 

2001MY, Lean Aged 

2001MY, Cyclic Aged 

100 150 200 250 300 350 400 450 500 

Temperature (°C) 

Figure II.3 Improvements in NOx Adsorber Thermal Durability with Cyclic Aging 

The catalyst manufacturer developed a number of theories for why lean/rich cycling could 

lead to more severe thermal aging when compared to lean aging alone. Based on these theories 

new catalyst formulations were developed for testing. The results for one of these 2001MY 

candidate technologies are shown as the pair of lines with solid and open triangles in Figure II.3. 

From the figure it can be seen that the lean aged catalyst performance was very similar between 

the 2000MY catalyst and the 2001MY catalyst with both technologies showing high NOx 

conversion efficiency even after extensive lean thermal aging (the two solid lines). When tested 

under conditions including both high temperatures (again 700� C) and repeated lean/rich cycling 

however, the new 2001MY catalyst formulation (the open triangle dashed line) gave substantially 

better performance when compared to the 2000MY catalyst showing almost no loss in 

performance at temperatures in excess of 300� C. Like the results from the Ford study described 

in the HD 2007 RIA, this data shows that repeated lean/rich cycling at high temperatures as 

required for NOx adsorber desulfation is not necessarily harmful to NOx adsorber durability. The 

results here indicate that progress is being made to develop NOx adsorber formulations that 

maintain high NOx conversion performance even after exposure to repeated desulfation events. 

The catalyst manufacturer in this case indicated that they still had a number of theories related to 

the observed thermal degradation under desulfation conditions and subsequent changes in NOx 

adsorber formulations to be tested. Therefore, they believed that opportunities remained to 

improve upon the results documented here. 

N

Ox C

o

nversion (%)


35

Highway Diesel Progress Review – June 2002 

The addition of alkali earth metals (e.g., potassium) to barium based NOx adsorber can 

significantly improve high temperature NOx adsorber performance as we discussed in Section 

II.F.1 above. However, early testing of NOx adsorber catalysts using potassium showed that 

potassium was highly mobile under high temperatures and had a strong affinity for the cordierite 

catalyst substrate typically used for NOx adsorber catalysts. It was observed that eventually most 

of the potassium in the catalyst washcoat would migrate into the cordierite substrate making the 

potassium unavailable for NOx storage and also weakening the catalyst substrate. This effect is 

believed to have been related to the loss of NOx adsorber performance after thermal aging 

observed in a number of prior test programs. To address this problem Corning Incorporated has 

been working to develop a new catalyst substrate material which is not reactive with potassium. 

The new material called Celcor NXTM has been shown to have no reactivity with potassium even 

up to temperatures of 1,000� C. This new material, which catalyst developers are only now 

beginning to test, has the potential to significantly improve the thermal durability of NOx adsorber 

catalysts by eliminating potassium migration into the catalyst substrate. Very early testing of the 

catalyst formulations applied to the new substrate reveal just that. This is an example of a new 

technology wholly unanticipated in the HD 2007 RIA that it appears will dramatically improve the 

long term durability of NOx adsorber catalysts. 

At the beginning of the progress review process long term thermal durability of NOx 

adsorbers subjected to repeated desulfation events was one of the key areas needing to be 

addressed as the technology was developed. While issues and opportunities for improvement 

remain, clearly substantial progress has been made with regard to the long term durability of the 

NOx adsorber catalyst. The progress to improve NOx adsorber durability observed in our review 

was clearly significant, and yet opportunities for further improvements seem to be possible. 

3. Methods and Performance for Desulfation (Sulfur Cleansing) 

Sulfur poisoning remains a challenge for the NOx adsorber catalyst even with diesel fuel 

sulfur capped at 15 ppm. Over time even very low levels of sulfur will lead to a loss of NOx 

adsorber performance as explained in Chapter III of the HD 2007 RIA. Therefore a means to 

cleanse sulfur from the NOx adsorber catalyst is a necessary step in order to ensure long term 

NOx adsorber performance. It has been shown that sulfur can be removed from the catalyst 

through a sulfur regeneration step (desulfation step) where the catalyst is heated to a temperature 

in excess of 650� C and exposed to fuel rich exhaust conditions. This desulfation process while 

effective at removing sulfur can also lead to damage of the NOx adsorber catalyst. The previous 

section of this report discussed advancements in catalyst and substrate materials that reduce 

dramatically the amount of catalyst damage caused by the high temperature conditions of 

desulfation. This section of the report will document new developments in the methods and 

procedures for desulfation intended to limit sulfur poisoning and improve the long-term 

performance of the NOx adsorber catalyst. 

36

Lambda

II. Progress Review of Engine Technologies

37

EPA scientists and engineers at the National Vehicle and Fuel Emissions Laboratory

(NVFEL) have been working to develop a procedure to desulfate a NOx adsorber catalyst in a

dual leg catalyst system (a discussion of the dual leg system can be found in Chapter III of the HD

2007 RIA). Figure II.4 below shows an example of a NOx adsorber desulfation event from this

test program. The figure shows that high exhaust temperature (in excess of 650� C) can be

created in an emission control system and that with the appropriate exhaust composition (fuel rich

operation, lambda < 1) sulfur is released from the catalyst. The sulfur release shown here is

primarily hydrogen sulfide (H2S) which is oxidized by a clean up catalyst in the EPA system.

Sulfur removal from the adsorber catalysts has been measured in the exhaust stream and

improvements in post-desulfation NOx reduction efficiency have been measured. The team is

continuing its work to include the fine-tuning of the desulfation strategy and the determination of

the effects of high desulfation temperature on NOx adsorber degradation for multiple desulfation

events. The effects of engine speed, engine load, catalyst temperature, and exhaust lambda on

desulfation will also be investigated.

NOx Adsorber Desulfation

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700 800

Time (s)

Concentration (ppm)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

H2S Adsorber Out Front NOx Adsorber Temperature (°C) Rear NOx Adsorber Temperature (°C) Desulfation Lambda

Figure II.4 xample of NOx Adsorber Desulfation

Catalyst development companies are also working to develop improved methods for NOx

adsorber desulfation. A number of important parameters are being investigated to learn of their

effect on the resulting NOx adsorber performance. Changes in catalyst formulation to improve

E
Highway Diesel Progress Review – June 2002 

thermal durability are an important part of this optimization and are discussed in the previous 

section of this report. Another parameter being investigated is the relative frequency of 

desulfation events. Work by Toyota reported in 1999 suggested that the larger sulfate crystals 

formed when a vehicle is operated on higher sulfur fuel can be more difficult to remove in a 

desulfation event and can eventually lead to a significant loss in NOx adsorber performance even 

with periodic desulfations.

15 Figure II.5 below, documents recent work by a major catalyst 

manufacturer to evaluate the desulfation performance of a NOx adsorber catalyst that is 

desulfated on a fixed time interval approximately equivalent to once per tank full. This approach 

is different from the desulfation work mentioned previously in the Ford Study and the DECSE 

program where desulfation was not attempted until significant levels of catalyst deterioration had 

occurred.16,17,18 The results in Figure II.5 show that NOx adsorber performance remains high even 

after more than 600 hours of catalyst aging with sulfur. The exceptionally good results shown 

here suggest that desulfation strategies which clean sulfur from the catalyst before high levels of 

sulfur have accumulated, can maintain long term NOx adsorber performance. In addition to 

providing better improved durability, this approach may also lead to improved fuel economy. 

Although, the desulfation event typically consumes fuel in order to raise temperatures (and as a 

reductant), it frees NOx storage sites increasing NOx storage capacity and allowing for a 

reduction in the frequency of NOx regeneration events. A decrease in the frequency of NOx 

regeneration lowers the fuel consumption associated with NOx regeneration. Therefore, a 

tradeoff exists between increasing fuel use for desulfation and decreasing fuel use of NOx 

regeneration. 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0 100 200 300 400 500 600 700 

250 o C 

300 o C 

Temperatures of 

NOx efficiency test 

Tested under Low Sulfur Fuel Simulation 

Regeneration Period Approximating Every Tank 

Durability Equivalent to 35,000 km 

Time-on-Stream (hours) 

Figure II.5 NOx Adsorber Performance with Repeated Desulfation Events NOx Conv

ersion (

%) 

38

II. Progress Review of Engine Technologies 

Engine manufacturers are also working to develop procedures and methods for NOx 

adsorber desulfation. Figure II.6 below shows progress by one of the largest diesel engine 

manufacturers in their evaluation of NOx adsorber desulfation over the long term. The figure 

shows the equivalent number of miles that a NOx adsorber catalyst could maintain an average 

efficiency in excess of 70 percent.

l

 The figure shows that methods for improving sulfur 

management plus unspecified changes in NOx adsorber formulations have almost tripled the life of 

the NOx adsorber catalyst compared to the experience from less than two years ago. The 

improvements in NOx adsorber life noted in the figure do not include the thermal durability 

improvements due to substrate improvements noted in Section II.F.2 above as those new 

technologies have not yet been sampled to the engine manufacturers for evaluation. 

Progress in Desulfation


(distance before significant sulfur poisoning)


500 

400 

300 

200 

100 

0 

Aug-00 Jan-02 LHD Regulatory Life MHD Regulatory Life HHD Regulatory Life 

Figure II.6 Improvements in NOx Adsorber Durability with Repeated Desulfations 

It is our expectation based upon the evidence made available to us during our progress 

review that even though substantial improvements in NOx adsorber durability have been made 

there remains a significant room for progress in the future. Given the short time window of this 

l

 The manufacturer chose the 70 percent efficiency threshold based upon their plans to develop a single 

NOx control technology for use across their entire range of engines in 2007. The HD 2007 rule requires that 50 

percent of a manufacturers engine sales to meet a 0.2 g/bhp-hr standard, but averaging provisions give 

manufacturers a flexibility to have 100 percent of their engines meet an average NOx standard of approximately 

1.2 g/bhp-hr. Most of the heavy-duty engine manufacturers that we met with during this progress review indicated 

that they will use the flexibilities allowed in the rule to produce a single NOx control technology for all of their 

engines in 2007. 

39 

Vehicle Miles ,000 
Highway Diesel Progress Review – June 2002 

review and the substantial lead time remaining before 2007, we believe that this progress is 

encouraging. 

4. Improvements in System Package Size and Integration 

During the HD 2007 rulemaking a number of diesel engine and vehicle manufacturers 

expressed concerns regarding the feasibility of applying the NOx adsorber catalyst to a diesel 

powered vehicle. Their concern was less focused on the functionality or durability of the catalyst 

technology itself but rather over the ability of the diesel engine system to be designed to operate 

in a manner that was compatible with the catalyst technology. As we started our review process 

this is the one area where we expected to find the smallest amount of progress. Given the long 

lead time remaining for 2007 and an expectation that system engineering would occur much closer 

to the production date, we had assumed that most manufacturers would still be at a very early 

stage in the process. What we discovered was that although manufacturers are indeed still in the 

pre-product development stage for heavy-duty NOx adsorbers, they have made considerable 

progress in developing systems that are compatible with the NOx adsorber technology. 

In our meetings with heavy-duty diesel engine manufacturers they characterized a number 

of changes in the industry that are ongoing due to their development efforts on NOx adsorbers 

and diesel particulate filters. They discussed a paradigm shift in the way that they thought of 

catalyst technologies, no longer as aftertreatment, but rather as an integral part of the engine 

emission control system design from the very beginning of the process. This had lead them to 

learn and develop a new vocabulary and new tools to talk and work as partners with the catalyst 

industry. This new language and new processes have accelerated their learning and is paying 

benefits in their technology development programs. One chief engineer at a major engine 

manufacturer characterized it this way, a year ago he said that he could only describe his technical 

expectations/specifications for the NOx adsorber catalyst in the most vague terms, and he could 

not accurately predict what changes could be made to his diesel engine to match the conditions 

required for a NOx adsorber to function. Over the last year he indicated that he has learned a 

great deal about the language and characteristics of catalyst technology and about the limits of his 

company’s engine technology. In his view, the ability to now provide very specific and accurate 

feedback to his catalyst company partners and to in-turn be able understand their feedback was 

the most important first step for him and his company to make progress on developing emission 

compliant engine and catalyst technologies for 2007. 

This characterization by a chief engineer and other similar discussions that we had with 

companies has left us with the impression that the industry is now undergoing a shift in how it 

works to develop emission control technologies. In many ways the companies appear to be 

changing to work as if they were a single vertically integrated manufacturer rather than as a series 

of steps in a supply chain. This change would appear to allow industry to take better advantage of 

the synergies between engine and catalyst technology. We were left with the impression, similar 

to that of the chief engineer described here, that this represents an important step in progress to 

40

II. Progress Review of Engine Technologies 

develop technologies for 2007. This is supported by the fact that many of these companies were 

able to show us real improvements in their engine and catalyst system integration in the short time 

since the rulemaking was completed. 

One the largest U.S. based heavy-duty diesel engine manufacturers provided graphical 

representations of their progress to calibrate a heavy-duty diesel engine for NOx adsorber 

regeneration. In this case their strategy is to use a single NOx adsorber catalyst that is 

regenerated by periodic operation of the engine such that the total exhaust is made to be fuel rich. 

This is accomplished by a sequence of changes in the air-handling system of the engine (i.e., 

turbocharger, EGR valve, and an intake throttle) along with optimized injection timing. Their 

early work on this strategy documented in Figures II.7 and II.8 as Aug00 (August 2000) shows 

that they were only able to accomplish the strategy at very light loads (brake mean effective 

pressure, BMEP <5 bar)m and when they did accomplish regeneration the fuel consumption rate 

increased by 20 percent. Since August of 2000, the company has continued to work to improve 

this strategy demonstrating in January of 2002 (Jan 02 in the figures) that they could accomplish 

NOx regeneration at engine loads up to15 bar (BMEP) with a fuel consumption increase of five 

percent. As the figures show, the company has made dramatic improvements in their engine 

technology in order to accomplish NOx regeneration and are approaching the internal targets that 

they have set for the technology in 2007. 

m Brake Mean Effective Pressure (BMEP) is a term used to describe normalized engine power. It is 

calculated as work per cycle divided by cylinder displacement per cycle. It allows the performance of engines of 

different sizes to be compared more easily. In Figure II.7 the value of 20 bar BMEP is indicated as the required 

BMEP for a heavy-duty diesel engine (the same power density as today’s diesel engines). Early testing by this 

manufacturer showed that NOx regeneration could only be accomplished at low loads (BMEP levels < 5 bar). 

Subsequent technology developments have allowed the manufacturer to demonstrate NOx regeneration at engine 

loads up to 15 bar (75 percent of full load). The manufacturer is continuing to make system improvements in order 

to accomplish acceptable NOx adsorber regeneration across the full range of diesel engine operation. 

41 
Highway Diesel Progress Review – June 2002 

Run Diesel Rich for NOx Trap Regeneration 

(target 70% NOx reduction w/o excessive smoke) 

25 

20 

15 

10 

5 

0 

Aug-00 Jan-02 Design Target for HD 

Figure II.7 Improvements in Ability to Create Regeneration Conditions Engine-Out 

Progress in Fuel Economy


(estimate at 70% NOx reduction over the cycle)


25% 

20% 

15% 

10% 

5% 

0% 

Aug-00 Jan-02 Fuel Economy Target 

Figure II.8 Improvements in Fuel Consumption associated with NOx Regeneration 

Although there were variations in demonstrated progress to develop these types of 

technologies among the different engine manufactures, the progress shown here in Figures II.7 

Fuel Penalty for NOx Reduction, % BMEP, Bar 

42

II. Progress Review of Engine Technologies 

and II.8 is representative of the kinds of progress that the industry has made as a whole. Diesel 

engine combustion fundamentals have been an important part of diesel engine emission controls 

for many years. For this reason the industry has developed sophisticated models and 

measurement tools to better understand combustion and to predict the effect of changes in 

combustion parameters. These tools are now being utilized to develop new combustion strategies 

consistent with NOx adsorber operation. Rapid progress as documented here is possible because 

of the industry’s fundamental understanding of diesel engine combustion. 

Another strategy for NOx adsorber regeneration is to employ multiple NOx storage 

catalysts which can then be taken “off-line” one at a time for periodic regeneration. Since the 

NOx regeneration event is accomplished off-line it can be done under reduced flow conditions in 

order to improve the NOx regeneration efficiency and to reduce fuel consumption. A team of 

EPA engineers and scientists have been working to evaluate this type of approach at NVFEL. 

The work on a dual-leg NOx adsorber system by this team was documented in the HD 2007 RIA 

and in subsequent peer reviewed publications.

19,20 The team has shown that a combined catalyzed 

diesel particulate filter and NOx adsorber catalyst system can deliver greater than 90 percent 

reductions in NOx and PM over a wide range of heavy-duty diesel engine operation. The work to 

date by this team has been conducted on a ‘proof of concept’ two leg NOx adsorber/PM trap 

system. This system is large and consequently would have poorer cold start and vehicle 

packaging properties than a single pass system. Concept work is underway to improve these 

aspects of the system. With a two leg system, each leg as to handle the full engine exhaust flow. 

A system composed of more legs would have a smaller overall catalyst volume. For instance, a 

four leg system would only have to be about thirty percent larger than a single leg system because 

only one leg would be regenerating at a time leaving the other three flowing the full exhaust. 

Lower cost fuel injectors and leg switching mechanisms are also being investigated by the team. 

The team has made significant progress in concept development for such a system with reduced 

size and cost that may offer benefits for heavy-duty diesel engines in performance and fuel 

consumption. 

Toyota Motor Corporation announced in 2000 that they were developing a new emission 

control technology that integrated a NOx adsorber catalyst on the surface of a particulate filter 

called Toyota’s diesel particulate NOx reduction (DPNR) system. In their press release, Toyota 

sited NOx and PM reductions in excess of 80% on a 2-ton diesel truck.21 On March 6 of 2002, 

Toyota announced that 60 diesel passenger cars equipped with the DPNR system would be 

introduced in monitor testing in Europe as a step toward Toyota’s planned introduction of a 

DPNR-equipped vehicle.22 Although a number of lean burn gasoline engines have previously been 

introduced with a NOx adsorber catalyst, we believe that this will be the first commercial 

application of the technology to a diesel powered vehicle. 

As part of our progress review, we requested that Toyota provide a DPNR equipped 

vehicle to EPA for testing at NVFEL. Toyota agreed to provide a vehicle and testing was 

completed in March of 2002 on a Toyota Avensis passenger car equipped with a 2 liter 

43

Highway Diesel Progress Review – June 2002 

turbocharged diesel engine and the DPNR system. The vehicle was representative of the fleet of 

60 vehicles that Toyota is putting into the monitor test program in Europe. Table II.2 below 

summarizes the results of testing at NVFEL on this vehicle. The final Tier 2 Bin 5 (corporate 

average for NOx) emission standards are provided in the table for reference. 

Table II.2 Toyota DPNR Vehicle Test Results at NVFEL 

NOx (g/mile) PM (g/mile) NMHC (g/mile) Fuel

† 

Test Cycle Test 

Results 

Tier 2 

Bin 5 

Test 

Results 

Tier 2 

Bin 5 Std 

Test 

Results 

Tier 2 

Bin 5 Std 

Economy 

(mpg) 

FTP75* 0.05 0.05 0.006 0.01 0.07 0.075 37 

US06** 0.14 0.005 0.07 0.19 35 

HWFET*** 0.001 0.075 0.002 - 0.12 - 53 

NYCC**** 0.003 - 0.007 - 0.04 - 22 

* Final Tier 2 FTP Bin 5 Intermediate Life (50k) standards, NMHC reported for NMOG 

** Final Tier 2 SFTP 4k standards, USO6 std is NOx + NMHC = 0.14, PM is a weighted Std 

*** Highway Fuel Economy Test NOx limit is 1.5 times the FTP standard 

**** New York City Cycle 

† Fuel economy numbers are actual test results. For comparison to reported City and Highway fuel 

consumption numbers the values here should be adjusted to account for historically observed test to real 

world shortfalls. For comparative fuel economy estimates the highway fuel consumption should be 

reduced by 22% (41 mpg) and the city/FTP by 10% (33 mpg). 

The Toyota system as applied in the Avensis passenger car demonstrates a number of 

things regarding overall system integration possibilities for NOx adsorber catalyst systems. The 

total integrated NOx adsorber and diesel particulate filter system as applied by Toyota is quite 

compact, fitting into the existing package volume of the Avensis passenger car. The required 

NOx regeneration events are also well integrated into the vehicles operation. Toyota performs 

the required periodic NOx regeneration events in a number of different ways depending upon the 

engine operating mode. Under some conditions Toyota operates the engine under a newly 

developed combustion mode called Low Temperature Combustion (LTC).

23 The Toyota system 

can also use a secondary in-cylinder injection event to accomplish NOx regeneration. At engine 

operating conditions where the secondary injection may be undesirable (e.g., where it could lead 

to unsatisfactory smoke or excessive temperatures) Toyota can accomplish NOx regeneration by 

supplemental fuel injection into the exhaust manifold. The combination of these three approaches 

allows the Toyota system to accomplish NOx regeneration across a broad range of diesel engine 

operation.

24,25 The DPNR vehicle shows that although the challenges of integrating a complete 

44

II. Progress Review of Engine Technologies 

NOx and PM emission control system into a diesel vehicle are difficult, they are not 

insurmountable. 

Our review of system engineering progress to develop a complete system solution to meet 

the HD 2007 emission standards has revealed an industry that is changing in response to new 

technologies while benefitting from its existing competencies in combustion system development. 

We see the progress in system developments as substantial with at least one manufacturer able to 

produce production like prototypes for testing. Although a number of challenges remain, we are 

convinced that industry is well on its way to develop NOx adsorber technologies for 2007. 

G. Changes to Engine Oil Formulations 

The possibility that changes to engine oil formulations would be needed in order to ensure 

long life and acceptable maintenance intervals for emission control systems was raised by various 

industry representatives during our progress review. This is a concern of EPA’s as well, and we 

have therefore been working to facilitate progress to address this issue. 

Engine oil components can affect emission control technologies in a number of ways. 

Sulfur in engine oil can contribute to catalyst poisoning in a manner similar to sulfur in diesel fuel. 

Therefore, it is desirable for engine oils to have low sulfur concentrations. Various metals in 

engine oils, including phosphorous and zinc, can also poison catalyst function over the long term. 

Therefore, it is desirable to reduce the metal content of engine oils. Metals in engine oil also are 

the major constituents of ash (in-organic, nonconsumable products of combustion) which are 

captured by the PM filter and which must be periodically removed. The frequency of the ash 

removal from the PM filter is proportional to the ash content of engine oil. Therefore, it is 

desirable to minimize the ash content of engine oils in order to reduce the frequency of PM filter 

maintenance. Unfortunately, sulfur, phosphorous, zinc, and other metals are present in engine oils 

primarily because they can provide some desirable characteristics to engine oils (e.g., base number 

control and anti-wear). Changes to engine oils will therefore likely require the development of 

new engine oil additives as well as engineering tradeoffs between desirable engine characteristics 

and catalyst characteristics. 

Changing engine oils in order to accommodate changes in engine emission control 

technologies is not a new phenomenon. Engine oils for heavy-duty diesel engines have gone 

through a successive series of changes over the last 20 years as engine design and operating 

characteristics have changed. Many of these technology changes have been due to changes in 

emission standards. Since changes to engine oil formulations linked to new engine technologies 

have been a normal part of technology development in the past, we were initially surprised by the 

number of companies and individuals that raised concerns about oil formulations for 2007. We 

now believe that the reason for this concern is the increase in the number of stakeholders in this 

process. 

45

Highway Diesel Progress Review – June 2002 

Historically heavy-duty engine manufacturers have been the primary determinants of 

future engine oil characteristics. Major diesel engine original equipment manufacturers (OEMs) 

such as Cummins and Mack would set their own engine oil standards in advance of the 

introduction of new engine technologies. Engine oil formulators would then develop new oil 

formulations that could meet all of the various individual OEM specifications and the oil would be 

marketed appropriately. Over time a new industry-wide oil specification would be agreed upon 

by representatives of the engine manufacturers, oil companies, and speciality chemical companies. 

The new specification would then become the industry standard for all heavy-duty diesel engines. 

This process has allowed industry to respond rapidly to changes in engine technologies while at 

the same time working towards a common engine oil product standard across the industry. What 

is changing in this field now is the need for another industry participant, the catalyst 

manufacturers, to become part of the engine oil specification cycle. The fact that this process will 

necessarily need to change to some extent may remove some control over the process from the 

heavy-duty engine manufacturers leading to increased concern over the process. However, it still 

appears likely that the engine manufacturers will serve as the final system integrators for the new 

technologies, and as such, will ultimately control much of this process. We are committed to 

working with industry to facilitate finding a consensus oil specification that respects engine and 

emission control system performance for 2007. 

An important first step in that process has already taken place with the Diesel Engine Oil 

Advisory Panel’s (DEOAP) designation of a new proposed category (PC-10) engine oil 

specification. This industry panel meets on a regular basis to develop a consensus specification 

for engine oil formulations. The newly designated PC-10 category will be for a low sulfur, low 

ash oil formulation for on-road heavy-duty diesel vehicles. EPA is represented on this panel and 

will work to promote information sharing and consensus building among industry members to 

help facilitate the definition of an appropriate engine oil specification for 2007. We believe that 

this is the appropriate avenue for changes to engine oil formulations to be decided by all 

stakeholders in a customer driven process. 

Progress is already being made to characterize the tradeoffs between changes in oil 

formulations that will be desirable for catalyst systems but which may be less desirable for engine 

systems. Two industry-wide research efforts have been started to determine the effect of engine 

oil formulations on engine wear and emissions component degradation. One program is the 

Advanced Petroleum Based Fuels – Diesel Emissions Controls Project (APBF-DEC). This 

program is investigating the effect of different oil formulations on heavy-duty diesel engine 

component wear and emissions. Another program looking at the effect of oil formulation on 

engine wear and emissions is an industry consortium organized by Southwest Research Institute 

(SwRI) titled Diesel After Treatment Sensitivity to Lubricants (DASL), Non-Thermal Catalyst 

Deactivation (N-TCD). In DASL the effects of lubricating oil components, such as sulfur, 

phosphorus, zinc, calcium and others, will be determined by measuring the deactivation of the 

emissions control systems as a consequence of oil exposure. The N-TCD portion is a 

research/mechanistic study designed to explore the mechanisms of emissions control system 

46

II. Progress Review of Engine Technologies 

deactivation as a result of oil exposure. The results from these and other test programs will serve 

to inform the process for engine oil specification. 

H. New Combustion Technologies 

We have been aware for some time that various research groups have been investigating 

novel diesel combustion concepts. These new concepts break the traditional NOx versus PM 

tradeoff typical of heterogenous diffusion controlled diesel combustion. They therefore have the 

potential to offer both low NOx and low PM emissions.

26 Our understanding of the various 

approaches has in the past lead us to conclude that the technologies would not be viable for 

production engines within the next ten years. Our visits with a number of diesel engine companies 

during this review has lead us to revise our opinion of these technologies somewhat. While no 

company believed that these novel approaches could be applied across the full spectrum of diesel 

engine operation and therefore could themselves enable compliance with the HD 2007 emission 

standards, several companies suggested that for a relatively narrow range of engine operation, 

these new approaches could potentially be applied, perhaps even as early as 2007. 

Nissan Motor Company has developed a diesel passenger car engine capable of operating 

under two distinct combustion modes. When engine torque demand is greater than approximately 

40 percent the engine operates using conventional diesel combustion. However, for lower engine 

operating loads, as typified by much of passenger car operation and some portions of heavy-duty 

diesel operation, the engine is operated with a low-temperature premixed combustion approach 

called modulated kinetics (MK) combustion. NOx and PM emissions are reduced by more than 

90 percent when the engine is operated in the MK combustion mode. When combined with a 

NOx adsorber catalyst Nissan has presented data that suggests that the technology may enable 

compliance with the light-duty Tier 2 corporate average NOx emission standard.

27 It is this 

synergistic application of novel combustion approaches under light load conditions with a NOx 

adsorber catalyst that can control NOx emissions at higher engine loads that potentially raises new 

opportunities for heavy-duty diesel engines. 

One of the challenges for the NOx adsorber catalyst is controlling NOx emissions at low 

exhaust temperatures (<250� C). Although new catalyst formulations are improving the low 

temperature characteristics of the NO adsorber (as we discussed in Section II.F.1 ), there may be 

additional improvements afforded by changes in diesel engine operation at light-loads as well. 

The Nissan data suggests that a diesel engine combustion system can be designed to operate 

under two different combustion modes without unacceptable compromises in either mode of 

operation (i.e., low engine out emissions at cool temperatures / light load using MK combustion 

and low tailpipe out emissions at higher temperatures / higher load due to a NOx adsorber 

catalyst). Whether or not such an approach can be applied to heavy-duty diesel engines is yet 

unknown. Our impression from visits with a number of engine manufacturers is that they are 

aggressively investigating this possibility. 

47

Highway Diesel Progress Review – June 2002 

In addition to the benefit of reduced engine out NOx and PM emissions at light-loads, 

novel combustion approaches may also be a means for NOx adsorber regeneration and possibly 

desulfation. The Toyota Low Temperature Combustion (LTC) technology like the Nissan MK 

combustion system gives very low engine out NOx and PM emissions. Additionally, the LTC 

technology produces fuel rich exhaust appropriate for NOx adsorber regeneration.

28 It would 

appear that approaches such as these may have the potential to improve the effectiveness of the 

NOx adsorber catalyst over a broader range of engine operation. The progress by several 

manufacturers for light-duty passenger cars in this area has been very impressive and causes us to 

consider that such approaches may be possible for heavy-duty diesel engines as well. 

Diesel engine manufacturers are working very hard to develop new and novel combustion 

technologies in order to reduce NOx and PM emissions while maintaining the good fuel economy 

associated with diesel engine technology. Although, we remain convinced that these technologies 

can not deliver the needed emission controls over much of the engine operating cycle alone, we 

do believe that they have some potential to be applied synergistically with the NOx adsorber 

catalyst in order to improve the overall emission control system effectiveness. 

48

III. Progress Review of Desulfurization Technology 

III. Progress Review of Desulfurization Technology 

As described above, the HD 2007 program regulates the heavy-duty vehicle and its fuel as 

a system. In the previous chapter, we described progress on the emission control technologies 

that are developing to meet the program’s emission standards. Specifically, our engine 

technology review involved company visits, a test program at the NVFEL, and DOE research 

programs. We concluded that substantial advancements in NOx adsorber and PM trap 

technologies have been made to date–only a year and a half since the HD 2007 rule was 

promulgated–and industry is on track to meet the program’s 2007 compliance date. 

This chapter describes our progress review on the technologies that will be used to 

remove sulfur from diesel fuel as well as specific refiner plans for producing the cleaner fuel. We 

followed a process very similar to our engine technology review. Specifically, our desulfurization 

technology review involved company visits and conference calls, a review of information 

submitted through the HD 2007 program’s reporting requirements, and a literature review. 

However, unlike the emission control technologies described in Chapter II, above, conventional 

diesel desulfurization technologies have been available and in use for many years. In the HD 2007 

rule, we projected that all refiners would be technically capable of meeting the 15 ppm sulfur 

standard with extensions of the same conventional hydrotreating technology that they are using 

today to meet the current highway diesel fuel sulfur standard of 500 ppm. 

Since the final rule, industry progress to date confirms our projections that conventional 

diesel hydrotreating technology could, in fact, be extended for use in compliance with the 15 ppm 

sulfur standard for highway diesel fuel. Refiners themselves have recognized this fact as well. 

Many of them are basing their compliance plans on the use of this technology. Consequently, in 

addition to reporting on the advancements that have been made to this technology to extend it for 

application to 15 ppm, this review focuses on the plans that refiners have begun to make to 

incorporate this technology into their refineries. 

New technologies are also being developed that offer promise for reduced costs. 

However, these technologies are not critical to the implementation of the HD 2007 program. 

Based on the conclusions we reached in the HD 2007 rule as well as new information that was 

made available to us during our progress review, we have concluded that the refining industry is 

making significant progress toward complying with the requirements of the HD 2007 program. 

A.	 Summary of the Highway Diesel Fuel Program 

Provisions 

The HD 2007 program establishes a sulfur limit of 15 ppm for highway diesel fuel. 

Refiners will be required to produce 15 ppm diesel fuel for use in highway vehicles beginning June 

1, 2006. At the terminal level, highway diesel fuel will be required to meet the 15 ppm sulfur 

49

Highway Diesel Progress Review – June 2002 

standard as of July 15, 2006. For retail stations and wholesale purchaser-consumers, highway 

diesel fuel sold as low sulfur fuel must meet the 15 ppm sulfur standard by September 1, 2006. 

These compliance dates are shown below in Table III.1. 

Table III.1 Industry Compliance Dates for the Highway Diesel Fuel Program. 

Refiners and Importers Terminals 

Retail Outlets and Wholesale 

Purchaser-Consumers 

June 1, 2006 July 15, 2006 September 1, 2006 

The program includes a combination of flexibilities available to refiners. First, refiners 

may take advantage of a voluntary transitional flexibility known as the Temporary Compliance 

Option (TCO), which includes an Averaging, Banking and Trading component (ABT). Second, 

the HD 2007 program includes hardship provisions for small refiners to minimize their economic 

burden in complying with the 15 ppm sulfur standard. Third, the program provides additional 

flexibility to refiners subject to the Geographic Phase-in Area (GPA) provisions of the Tier 

2/Gasoline Sulfur program (65 FR 6698, February 10, 2000) which will allow them the option of 

staggering their gasoline and diesel fuel related investments. Finally, the program contains a 

general hardship provision for which any refiner may apply on a case-by-case basis under certain 

conditions. 

1. Temporary Compliance Option 

Under the HD 2007 program’s TCO, a refinery may voluntarily produce up to 20 percent 

of its total highway diesel fuel at the existing highway diesel fuel sulfur standard of 500 ppm, 

determined on an annual basis. The remaining 80 percent of the highway diesel fuel produced at 

that refinery during the year must meet a sulfur standard of 15 ppm. The TCO also includes a 

regional ABT component. Figure III.1 presents the Credit Trading Regions (CTRs) into which 

50

VII 

III. Progress Review of Desulfurization Technology 

the United States is divided for the HD 2007 program. These regions are largely based upon the 

Department of Energy’s Petroleum Administrative Districts for Defense (PADD). However, 

Alaska and Hawaii, which are part of PADD V, are separate CTR’s under the HD 2007 program. 

I II 

III 

IV 

V 

VI 

I II 

III 

IV 

V 

VI 

VII 

Figure III.1 Map of the Credit Trading Regions Under the HD 2007 Program. 

If a refiner opts to use the ABT component of the HD 2007 program, it may produce 

more than 80 percent of its highway diesel fuel as low sulfur diesel fuel and generate credits based 

on the volume of highway diesel fuel produced at 15 ppm that exceeds the 80 percent 

requirement. Within the same CTRn, these credits may be averaged with another refinery owned 

by that refiner, banked for use in future years, or sold to another refinery. 

While the minimum low sulfur diesel fuel requirement under the TCO is 80 percent, we 

expect that most refineries will focus on production of either 15 ppm or 500 ppm sulfur diesel 

fuel. Certain refineries will find it more economically advantageous to install the necessary 

equipment to produce all of their highway diesel fuel at the 15 ppm sulfur level and generate 

credits. Conversely, other refineries may find it advantageous to continue producing all of their 

highway diesel fuel at the 500 ppm sulfur level during the TCO, by obtaining credits to 

demonstrate compliance. The benefits of this voluntary option, for those refiners that choose to 

take advantage of it, are described in detail in the final rule. 

n The ABT program has certain additional limitations for any state with an EPA-approved waiver from 

the federal program which is more stringent than the federal program. This is explained in more detail in the 

preamble to the HD 2007 rule. 

51 
Highway Diesel Progress Review – June 2002 

2. Hardship Provisions 

a. Small Refiner Hardship Provisions 

In addition to the TCO, the HD 2007 program contains special provisions for qualifying o small business refiners. These flexibility provisions will provide small business refiners with 

additional time to meet the 15 ppm sulfur standard or balance investments needed to produce low 

sulfur gasoline. Approved small refiners under the highway diesel fuel program may choose from 

the following three compliance options: 

500 ppm Option. A small refiner may continue to produce and sell diesel fuel meeting the 

current 500 ppm sulfur standard for four additional years, until May 31, 2010, provided 

that it reasonably ensures the existence of sufficient volumes of 15 ppm fuel in the 

marketing area(s) that it serves. 

Small Refiner Credit Option. A small refiner that chooses to produce 15 ppm fuel prior 

to June 1, 2010 may generate and sell credits under the broader TCO. Since a small 

refiner has no requirement to produce 15 ppm fuel under this option, any fuel it produces 

at or below 15 ppm sulfur will qualify for generating credits. 

Diesel/Gasoline Compliance Date Option. For small refiners that are also subject to the 

Tier 2/Gasoline sulfur program (40 CFR Part 80, Subpart H), the refiner may choose to 

extend by three years the duration of its applicable interim gasoline standards, provided 

that it also produces all of its highway diesel fuel at 15 ppm sulfur beginning June 1, 2006. 

Twenty-one refineries owned by 16 refining companies have applied for and/or been 

approved for small refiner status under the HD 2007 program. Thirteen of these refineries were 

grand-fathered into the HD 2007 program because they have approved small refiner status under 

the low sulfur gasoline program.p The remaining eight refineries have applied for small refiner 

status under the HD 2007 program; their applications are pending. 

o The rationale behind these provisions as well as the eligibility requirements for them are described in 

detail in the preamble to the HD 2007 rule. 

p The low sulfur gasoline program also contains provisions for small refiners which allow them more 

time at less stringent interim standards to comply with the national gasoline standards. Currently, 12 refineries 

owned by nine refining companies have approved small refiner status under the low sulfur gasoline program. 

52 
III. Progress Review of Desulfurization Technology

q

 The GPA program was established under the Tier 2 rule. t provides temporarily less stringent

standards for gasoline sold in the West and Alaska thereby giving some refiners additional time to comply with the

national low sulfur gasoline standards.

53

b. GPA Refiner Provision

The HD 2007 program also includes flexibility for refiners who supply fuel to the West

and Alaska. Specifically, the program allows refiners who supply fuel to the Geographic Phase-in

Area (GPA), Figure III.2, below,

q

 to stagger their gasoline and diesel desulfurization investments.

Refiners that comply with the 15 ppm sulfur standard by June 1, 2006 for all of their highway

diesel fuel production may receive a two-year extension of their interim GPA gasoline standards

for 2006, that is through December 31, 2008.

Figure III.2 Geographic Phase-in Area.

c. General Hardship Provision

In addition to the small refiner and GPA flexibility provisions described above, the HD

2007 program includes two general hardship provisions:

• Temporary waivers based on extreme unforseen circumstances

I
Highway Diesel Progress Review – June 2002 

• Temporary waivers based on extreme hardship circumstances 

Under the first provision, EPA may, at its discretion, permit domestic or foreign refiners 

to seek a temporary waiver from the 15 ppm diesel fuel sulfur standard under certain rare, 

unanticipated circumstances, such as a refinery fire or a natural disaster. 

The second general hardship provision provides a waiver for relief based on extreme 

hardship circumstances. This provision was designed for refiners that may face particular 

difficulty in complying with the 15 ppm sulfur standard in the lead time provided (for example, 

due to the inability to raise capital for desulfurization investments or relatively poor economies of 

scale). 

B. The Review Process 

1. Company Meetings and Visits 

We conducted this review over the last year and a half tracking industry’s progress in 

improving and implementing desulfurization technologies to produce 15 ppm sulfur diesel fuel. 

We have spoken to, met with, or visited five major technology vendors and more than 30 refining 

companies since promulgation of the HD 2007 rule. 

The purpose of these meetings was for us to affirm our final rule projections that 

extensions of existing diesel fuel desulfurization technology are feasible and will be used for 

compliance. During our meetings with technology vendors, we asked industry to estimate, based 

on each company’s experience, the current state of desulfurization technology development and 

implementation. Specifically, we sought answers to the following questions: 

• What is the capital cost of your technology? 

• What are the operating costs associated with your technology? 

• Will your technology require an increase in capacity? 

• What is the hydrogen consumption requirement of your technology? 

• When do you expect commercial introduction of your technology? 

• Can your technology be used in the revamp of existing equipment? 

In addition to discussions with technology vendors, we also held conversations with 

refining companies regarding the implementation of diesel desulfurization technologies to produce 

15 ppm sulfur diesel fuel. During our meetings with refining companies, we polled them on their 

plans for complying with the requirements of the HD 2007 program. Specifically, we posed the 

following questions to each company for each of their refineries: 

54

III. Progress Review of Desulfurization Technology 

• Do you plan to construct a completely new hydrotreating unit? or 

• Will you revamp an existing unit? 

• Will you be able to comply by simply changing catalysts? 

•	 Do your plans include using any of the “new” desulfurization technologies that 

have recently become available? 

•	 Assuming compliance by June 1, 2006, will the volume of ultra low sulfur diesel 

you produce likely be greater than, less than, or the same as your current 

production? 

•	 Do any synergies exist in complying with both the low sulfur gasoline and HD 

2007 programs? 

With this information, we evaluated the current status of diesel desulfurization 

technologies and refiners’ plans for implementing the technology (revamped versus new 

equipment) to produce 15 ppm sulfur diesel fuel. The information shared during these meetings 

and visits with the regulated industry provided the primary basis for our conclusions regarding 

industry’s progress. Some of the information shared by industry was designated as CBI and as 

such cannot be described in detail. 

2. Information Obtained Through Reporting Requirements 

As described above, the HD 2007 rule contains registration and reporting requirements for 

the petroleum industry. The information obtained through these requirements will 1) provide an 

essentially complete and current picture of the universe of highway diesel fuel suppliers that exist 

at the beginning of the program, 2) help us to track industry’s progress in implementing the 

program and 3) enable us to evaluate compliance with the program once it has begun. 

a. General Requirements 

• Registration Information 

Refiners and importers that currently or in 2006 expect to produce or supply highway 

diesel fuel were required to register with us by December 31, 2001. 

• Pre-Compliance Reports 

Refiners or importers that are planning to produce or import highway diesel in 2006, are 

required to submit an annual pre-compliance report. These reports are required from 

2003 through 2005 and must contain the following information: 

- Volume estimates of 15 ppm sulfur fuel and 500 ppm sulfur diesel fuel that will be 

produced at each refinery, 

55

Highway Diesel Progress Review – June 2002 

- A projection of how many credits will be generated or must be used by each 

refinery (for those refineries planning to participate in the credit trading program), 

and 

- Information outlining each refinery’s schedule for compliance including 

information regarding engineering plans (e.g., design and construction), the status 

of obtaining any necessary permits, and capital commitments for making the 

necessary modifications to produce 15 ppm sulfur highway diesel fuel. 

We plan to issue an annual report that summarizes the information contained in the precompliance reports (without compromising the confidentiality of individual refiners and 

importers). Our annual report will provide information, summarized and aggregated on a regional 

basis, on the volumes of 15 ppm and 500 ppm sulfur highway diesel fuel planned to be produced, 

and estimates of the number of credits that refineries expect to generate or use. This will provide 

industry with informed projections of the highway diesel market and allow them to adjust their 

plans accordingly. 

b. Small Refiners 

• Registration Information 

In addition to the basic registration requirements above, a refiner seeking small refiner 

status under the HD 2007 program had to apply for this status as a part of its registration 

(including corporate employment and crude oil capacity information as specified in the 

regulations). The application had to include which small refiner option the refiner expects 

to use at each of its refineries. 

• Pre-Compliance Reports 

In addition to the information required for all refiners above, small refiners must provide 

additional information in their pre-compliance reports. The information required varies 

according to which small refiner option the refiner plans to use. The following paragraphs 

summarize the supplementary information required for each small refiner option. 

i. 500 ppm Option 

The pre-compliance report for a refiner planning use the 500 ppm Option must make a 

showing that sufficient sources of 15 ppm sulfur fuel will likely exist in the area. If after 2003 the 

sources of 15 ppm sulfur fuel decrease, the pre-compliance reports for 2004 and/or 2005 must 

identify this change and must include a supplementary showing that the sources of 15 ppm sulfur 

fuel are still sufficient. 

56

III. Progress Review of Desulfurization Technology 

ii. Small Refiner Credit Option 

Pre-compliance reporting for small refiners choosing the Small Refiner Credit option is 

identical to that for the 500 ppm sulfur option (that is, if the small refiner is also producing 500 

ppm sulfur highway diesel fuel), with the additional requirement that the refiner also report on any 

credits it expects to generate and sell. 

iii. Diesel/Gasoline Compliance Date Option 

Pre-compliance reports from small refiners that expect to use the Diesel/Gasoline 

Compliance Date Option must provide information showing that diesel desulfurization plans are 

on track. In addition to the information described above for refiners in general, the precompliance reports from a small refiner that expects to use this option need to reasonably show 

that the refiner will be in a position by June 1, 2006, to produce 100 percent

r

 of its highway diesel 

fuel at the 15 ppm sulfur level. 

c. GPA Refiners 

As with small refiners expecting to use the Diesel/Gasoline Compliance Option above, 

pre-compliance reports from any refiners or importers expecting to use the extension of the GPA 

gasoline sulfur standards must provide information showing that diesel desulfurization plans are 

on track. In addition, pre-compliance reports from a prospective GPA refiner need to reasonably 

show that the refiner will be in a position by June 1, 2006 to produce 100 percent of its highway s diesel fuel at the 15 ppm sulfur level. 

3. Literature Review 

The final step of our progress review was a literature search. We conducted a search for 

information related to the production of 15 ppm sulfur diesel fuel, including conventional and 

emerging desulfurization technology developments as well as announcements of specific refiner 

plans for producing 15 ppm sulfur diesel fuel. 

The results of this search are located in Appendix C of this report. 

r The total volume of 15 ppm sulfur diesel fuel must meet or exceed 85 percent of the small refiner’s 

baseline volume (which is based on data for 1998 and 1999), except for 2006 where the total volume must meet or 

exceed 50 percent of the baseline volume. 

s

 The 85 percent baseline volume requirement also applies to the GPA option. 

57 
Highway Diesel Progress Review – June 2002 

C. Desulfurization Technology Progress 

1. Final Rule Estimates and Conclusions 

In Chapter IV (Fuel Standard Feasibilityt) of the HD 2007 rule RIA, EPA concluded that 

it would be feasible for refiners to achieve the 15 ppm sulfur standard using extensions of 

conventional diesel desulfurization technology. This feasibility conclusion was based on 

conversations with the vendors of highway diesel fuel desulfurization technology, including Akzo 

Nobel, Criterion Catalysts, Haldor Topsoe, IFP and UOP. This view was further corroborated by 

refiners with whom EPA spoke as it developed the final rule. 

In meeting the 15 ppm diesel fuel sulfur standard, which is expected to result in highway 

diesel fuel being desulfurized down to about seven ppm, refiners are expected to take a number of 

actions, including the following: 

•	 Upgrade to a higher activity catalyst in the existing reactor of a revamped highway diesel 

hydrotreater, 

•	 Add a second reactor vessel to increase catalyst volume with some or most of the reactor 

volume being comprised of a nickel-molybdinum (Ni-Mo) catalyst, 

• Scrub the hydrogen sulfide (H2S) out of the recycle hydrogen gas, 

•	 Use improved liquid distributors to improve the distribution of the liquid over the catalyst 

bed, 

•	 Increase the hydrogen partial pressure by increasing the hydrogen purity available from the 

source, or increase the amount of recycle gas, 

•	 Increase the reactor temperature of the current highway diesel hydroteater, or operate the 

first reactor of a new hydrotreater at a higher temperature, 

•	 Scrub the H2S from the liquid/gas mix between the first reactor (existing reactor in the 

case of revamps) and second reactor. 

The Agency estimated that achieving a 15 ppm sulfur cap using a conventional Ni-Mo 

catalyst and applying a combination of the changes described above would require 480 standard 

t http://www.epa.gov/otaq/regs/HD 2007/frm/ria-iv.pdf 

58 
III. Progress Review of Desulfurization Technology 

cubic feet of hydrogen per barrel (scf/bbl) of diesel feed. This hydrogen consumption value 

assumed a diesel fuel which would be composed of a typical mix of blendstocks. 

The technology choice for achieving a 15 ppm sulfur level must also consider whether the 

existing hydrotreater will be revamped, or whether it will be replaced with a new highway diesel 

fuel desulfurization unit. After discussing this issue individually with vendors and refiners and at a 

refining industry technology sharing meeting, EPA estimated that 20 percent of highway diesel 

fuel, on average, would be produced by new highway diesel hydrotreaters, while the other 80 

percent of the volume would be produced by revamped hydrotreaters. EPA also concluded that 

sufficient time and resources (engineering and construction, in particular) were available for 

implementation of the technology by the program’s compliance date. 

2. Progress Since the Final Rule 

This section describes the progress made in deep desulfurization technology for meeting 

the 15 ppm sulfur standard since the HD 2007 rule was promulgated. During late 2001 and early 

2002, we held discussions with Akzo Nobel, Criterion Catalysts, Haldor Topsoe, IFP, and UOP 

about improvements in their conventional deep desulfurization technologies for diesel fuel. 

a. Progress with Conventional Diesel Desulfurization Technology 

As stated above, we concluded in the HD 2007 rule RIA that meeting the 15 ppm sulfur 

standard would be feasible using extensions of known conventional, fixed bed desulfurization 

technology. This conclusion was based on conversations with diesel desulfurization technology 

companies and refiners that were drawing upon some limited data and expertise on the issue. In 

most cases, these firms did not have commercial data and had only limited data from their pilot 

plants upon which they made their conclusions. However, they did have some commercial 

experience with deep desulfurization units which serve as first stages for upgrading diesel fuel to 

meet cetane or density specifications, or to produce highway diesel fuel under the European tax 

incentives for meeting the 50 ppm sulfur standard which applies there. 

Since the final rule, these vendors have been running desulfurization tests in their pilot 

plants using various feedstocks and at varying conditions for meeting the 15 ppm sulfur standard. 

In addition, the vendors have been working with several refiners who have been running tests 

using their existing highway diesel hydrotreaters operated under conditions where they could 

achieve 10 to 15 ppm sulfur diesel fuel. After collecting these additional data, the vendors are all 

concluding, with certainty, that the 15 ppm sulfur standard is achievable with conventional 

technology treating the diversity of diesel fuel blendstocks comprising diesel fuel today. 

The feasibility of complying with the highway diesel fuel sulfur standard is enhanced even 

further through advances in conventional technologies. These advances are associated with 

59

Highway Diesel Progress Review – June 2002 

improvements in existing catalyst technology or other developments associated with diesel 

desulfurization. The improvements in catalyst technology are summarized here and are organized 

into three primary areas: 1) incremental improvements in current catalyst technology, 2) 

significant improvements in the coatings used on catalysts, and 3) improvements on the substrate 

used with catalysts. The discussion about improvements in catalysts is followed by a discussion 

about several other important issues including reactor internals, the amount of hydrogen needed 

for desulfurizing highway diesel fuel and the projected fraction of new versus revamped units. 

i. Incremental Improvements in Catalyst Technology 

Three vendors with whom we spoke regarding diesel desulfurization mentioned that their 

companies were planning to announce a new line of desulfurization catalysts

u

 before the June 

2006 compliance date for the HD 2007 program. IFP is one of these. Its previous catalysts were 

designed primarily for realizing improvements in density and cetane for the European and Asian 

markets. However, IFP announced that, by the end of 2002, it will be selling a new line of 

catalysts for the U.S. refining industry which will focus strictly on deep desulfurization of diesel 

fuel for meeting the 15 ppm sulfur standard. Haldor Topsoe also announced that it would make 

another line of catalysts available in 2002 or 2003. Finally, Criterion Catalysts stated that it would 

be making another line of catalysts available before the program’s June 2006 compliance date. 

These vendors did not provide estimates of the desulfurization efficiency improvement that these 

catalysts would deliver. However, the past improved catalyst introduced by Haldor Topsoe 

(comparing TK-574 to TK-554) would allow an existing hydrotreater to desulfurize the same 

untreated feed at the same reactor conditions down to 280 ppm versus 400 ppm with the previous 

catalyst. Criterion’s most recent catalyst introduction, Centinel, is 80 percent more active than 

conventional catalysts used in the mid 1990s. This increased activity is achieved by better 

dispersion of the active metal on the catalyst substrate. While these new or improved catalysts are 

not sufficient to enable an existing hydrotreator to meet the 15 ppm sulfur standard, they can help 

to reduce the size of the second reactor, and the amount of additional catalyst needed. 

ii. Catalyst Coatings 

Last year, Akzo Nobel announced a new highly active catalyst named Nebula which offers 

a different way in which coatings are used for catalysts. A typical catalyst is composed of two 

parts: an active coating which contains metals and a generally inactive substrate. For Nebula, 

Akzo Nobel concentrated the metal coatings and omitted the substrate. Because of the very high 

metals content, Nebula costs several times more than conventional catalysts. The higher activity 

of the Nebula catalyst leads to an increased tendency for coking, which must be countered by 

using a high hydrogen partial pressure, resulting in a higher hydrogen consumption. (The 

u Desulfurization catalysts are manufactured by applying Cobalt-Molybdenum (Co-Mo) or NickelMolybdenum (Ni-Mo) metals to a substrate. 

60 
III. Progress Review of Desulfurization Technology 

hydrogen consumption is higher because a higher percentage of the aromatics are saturated to 

nonaromatic compounds.) According to Akzo Nobel, a refiner may be able to meet the 15 ppm 

sulfur standard by simply replacing its existing catalyst with Nebula and providing significantly 

more hydrogen (which may possibly require the addition of a hydrogen plant). However, it is 

conceivable that a refinery located on the Gulf Coast which has an external supply of hydrogen 

could meet the 15 ppm sulfur standard with only a catalyst change, avoiding significant capital 

costs. 

While Nebula is a new catalyst that could avoid some or much of the capital investment 

that would otherwise be required for meeting the 15 ppm sulfur standard, another company said 

that it is experimenting with using its previously developed catalyst technology for meeting the 15 

ppm sulfur standard. Criterion catalysts indicated that it is working with some refiners to use its 

Synshift catalyst technology to meet the 15 ppm sulfur standard. The Synshift technology is a 

ring opening technology that would open at least one of the aromatic rings of polyaromatics. 

Like the Nebula catalyst, the Synshift catalyst would trade higher hydrogen consumption for 

capital costs as an existing large, higher pressure (1000 psia) highway diesel fuel reactor could be 

used to meet the 15 ppm sulfur standard with potentially only a change in catalyst. The result of 

this commercial testing is expected to be made available within a year. A more complete 

summary of Synshift is contained in Chapter IV of the HD 2007 RIA. 

iii. Catalyst Substrate 

Another catalyst vendor shared some information about its catalyst development program 

which involves advances in the geometry of its substrate. These advances have resulted in 

significant improvements in the contact of diesel fuel with the catalyst. The vendor also shared 

that it is combining its substrate technology with other reactor enhancements to further increase 

the contact between diesel fuel and the catalyst and hydrogen. Preliminary tests suggest that this 

combination could improve the catalyst activity by a factor of three. While this technology is still 

under development in the laboratory, the vendor is optimistic that it will be commercially available 

by 2006. 

iv. Reactor Internals 

Diesel desulfurization technology improvements extend beyond the desulfurization 

catalyst. As described above, a high quality distributor for distribution of the liquid feed over the 

catalyst bed is necessary to maximize the desulfurization capability of the reactor. Since the final 

rule, IFP announced an improved distributor called EquiFlow. IFP presented a paper on 

EquiFlow at the National Petrochemical and Refiners Association (NPRA) Annual Meeting in 

March 2001. A comparison of its EquiFlow distributor to a conventional distributor shows an 

impressive improvement in temperature consistency both just below the top of the catalyst bed 

and at the exit at the bottom of the catalyst bed. The improved temperature gradients provide a 

sound basis for concluding that the new IFP distributor would 1) improve the distribution of the 

61

Highway Diesel Progress Review – June 2002 

liquid thus avoiding channeling around the catalyst bed, and 2) reduce hot spots in the reactor 

thus improving diesel fuel color and avoiding unnecessary coke build up in the catalyst bed. This 

distributor as well as other improved distributors that are already available provide refiners an 

important array of options for meeting the 15 ppm sulfur target. 

b. Other Issues 

The hydrogen consumption of a diesel hydrotreater unit is, in most cases, the highest cost 

line item associated with deep diesel fuel desulfurization. We based our cost estimates for 

producing 15 ppm sulfur diesel fuel on the hydrogen consumption provided by the two vendors 

which provided information on the capital, utility, and other inputs required for diesel fuel 

desulfurization. During our conversations on diesel desulfurization technology, we questioned the 

vendors on their most recent estimates for hydrogen consumption. Specifically, we inquired 

whether our hydrogen consumption estimate of 480 (scf/bbl) for desulfurizing a typical 

undesulfurized diesel feed down to under 15 ppm sulfur was still reasonable. All of the vendors 

agreed that it was. 

We also inquired about whether refiners would be revamping their existing diesel fuel 

desulfurization units, or removing those from service and installing new units. The vendors 

indicated that the refiners who were further along in the planning process were intending to 

revamp their existing desulfurization units. This information was corroborated, as described in 

Section E, below, by the conversations and meetings we held with refiners. Because most refiners 

have still not finalized their compliance plans for producing 15 ppm sulfur diesel fuel, the exact 

fraction of highway diesel fuel that will be produced by revamped units versus new units cannot 

be determined at this time. However, given this information and the absence of any other 

evidence to the contrary, we continue to believe that our previous 80 percent revamp / 20 percent 

new unit projection was reasonable. 

3. Shared Desulfurization or Hydrogen Units 

Sharing desulfurization or hydrogen units between or among refineries can greatly reduce 

the per-gallon capital costs for complying with the 15 ppm sulfur standard. This is because larger v desulfurization and hydrogen units benefit from the economies of scale that larger units offer, 

with smaller refiners having more to gain than larger refiners. For example, a small refiner that 

makes highway diesel fuel would make an agreement with another refiner, either small or large, to 

share the cost of building and operating a common hydrotreater serving the desulfurization needs 

of two or more neighboring refineries. This same investment approach could be used to build 

common hydrogen generating plants. For example Praxair, a producer of hydrogen in the Gulf 

v As an example, smaller desulfurization units incur similar design and instrumentation costs as larger 

units, despite the smaller volumes treated. 

62 
III. Progress Review of Desulfurization Technology 

Coast, announced its intention to build two 100 million cubic feet per day hydrogen-producing 

facilities there to satisfy the upcoming hydrogen demand by a number of refiners to desulfurize 

their gasoline and highway diesel fuel. Actions such as these will lower the cost of complying 

with the 15 ppm sulfur standard. 

4. Emerging Technologies 

The HD 2007 rule also contained brief descriptions of developmental diesel fuel 

desulfurization technologies which may serve as alternatives for meeting the 15 ppm sulfur 

standard if they are proven successful. One such diesel desulfurization technology was announced 

in early 2002 by Linde Process Plants Incorporated and Process Dynamics Incorporated. As 

explained by the engineers developing this process, the process is also a fixed bed desulfurization 

technology using conventional desulfurization catalysts, but it incorporates a significant amount of 

product recycled back to the reactor feed as the means to overcome the hydrogen mass transfer 

limitations which normally plague conventional fixed bed diesel desulfurization. Operating closer 

to the kinetic potential for desulfurization, this process is capable of space velocities an order of 

magnitude greater than those using conventional fixed bed desulfurization. Thus, capital costs are 

significantly reduced and cycle lengths are extended. The Linde and Process Dynamics engineers 

also explained that a current highway diesel fuel desulfurization unit revamped using this 

technology would recover the incremental operating costs of this added unit through improved 

reaction heat recovery, thus incurring a small payback. This process is being installed in a U.S. 

refinery with an expected start-up in the summer of 2002. If the commercial demonstration unit 

performs as well as the pilot plant data suggests, it could provide a much lower cost option for 

meeting the 15 ppm sulfur standard even in 2006. 

Another technology is the Phillips S-Zorb process which has been demonstrated in a 

laboratory, and more recently in a pilot plant. The S-Zorb process works by adsorbing the sulfur 

molecules of the hydrocarbon onto a catalyst which then cleaves the sulfur molecule from the 

hydrocarbon molecule. To avoid saturating the catalyst with sulfur, the catalyst is constantly 

removed from the reactor and regenerated. Petrostar and UniPure have developed another type 

of technology which chemically oxidizes and extracts sulfur from diesel fuel. Both the Petrostar 

and UniPure processes have been demonstrated in the laboratory, and the Petrostar process has 

been demonstrated in a pilot plant. 

Although the emerging technologies are unnecessary for refiners’ compliance in 2006 

since extensions of conventional technology can meet the 15 ppm sulfur standard, they may offer 

lower costs for some refiners, particularly those that are able to delay production of 15 ppm sulfur 

diesel fuel until 2010 by taking advantage of the program’s flexibilities. Based on our 

conversations with these technology vendors, some of these technologies may require an 

upstream desulfurization unit for removing the bulk of the sulfur in diesel fuel, thus, they would 

likely be installed in series as a revamp to an existing conventional diesel fuel hydrotreater. An 

exception to relying on revamps is that Petrostar may be able to adapt its pre-extraction 

63

Highway Diesel Progress Review – June 2002 

technology to meet the 15 ppm sulfur standard from high sulfur untreated feedstocks, and 

UniPure is working on adapting its process for higher sulfur feeds. These technologies consume 

little or no hydrogen, which provide an operating cost advantage, especially to those refiners short 

on hydrogen. This quality also makes these processes excellent candidates for reprocessing 

off-specification distillate that is generated as a result of pipeline shipment and tank storage 

cross-contamination. Therefore, if installed at terminals, these alternative processes could play an 

important role in helping to maintain the integrity of highway diesel by reducing the volume of 

highway diesel fuel that is downgraded to other products. 

D. Refiners’ Plans for Producing 15 ppm Diesel Fuel 

As described above, the HD 2007 rule was published only last year and refiners have four 

to eight years to meet the 15 ppm diesel fuel standard. Given the timing of this progress review 

report relative to the June 2006 compliance date for the HD 2007 program, we focused our 

progress review efforts on information and activities since January 2001, related to the 

desulfurization technologies. However, it is important to note that some refiners will have the 

capability to produce 15 ppm sulfur diesel as early as next year, and small volumes are being 

produced today to enable retrofit programs in transit and school bus programs across the country. 

The refining industry is very diverse and every refinery within the industry is unique. 

There are approximately 112 refineries that produce highway compliant diesel fuel in the U.S., 

ranging from very large refineries with crude capacities in excess of 450,000 barrels per day (bpd) 

to the relatively small that process as few as 5000 bpd. Some of these refineries are owned by 

small businesses and as such may qualify for the small refiner hardship provisions of the HD 2007 

program. Likewise, refineries located in the West or Alaska that produce both gasoline and 

highway diesel fuel may benefit from the program’s GPA refiner provision. Some refineries are 

already well positioned to comply with the program’s requirements (and, in some cases, have 

announced their specific plans to do so) while other refineries are exploring technology options 

for producing 15 ppm diesel fuel. 

While refineries are very diverse in terms of their corporate ownership, capacity, 

configuration, location, and product slate, they will, in general, follow a common pathway toward 

compliance with the requirements of the HD 2007 program. Progress toward compliance can be 

assessed by reviewing refiners’ transitions from one stage to the next along the compliance 

pathway over time. That is, we can compare how many refiners are at a given stage from one 

year to the next until the program is fully implemented. Until the end of 2002, most refiners will 

be in the planning stage to determine how they will comply with the program’s requirements. 

After refiners have made their technology selections (including detailed design and engineering), 

they will begin the permitting process to obtain the necessary approvals for revamping existing or 

installing new refinery equipment. Finally, after the plans have been established and the necessary 

permits have been obtained, refineries will begin the final stage of the pathway toward 

64

III. Progress Review of Desulfurization Technology 

compliance–engineering, construction, and ultimately start-up. These stages are described in 

more detail below. 

1. Steps in the Planning Process for Producing Low Sulfur Diesel 

a. Strategic Planning – Deciding What to do and When 

Strategic planning occurs once upper management has determined that a regulation will 

affect a facility. As the word “strategic” implies, it is at this stage that upper management decides 

on a response to the regulation that will position the company most advantageously relative to its 

competitors. Input may include order-of-magnitude estimates of what compliance costs could be; 

or, how the bottom line may be affected if the decision is made not to comply and to instead shift 

product into other markets. Specific planning begins once management determines that, 

strategically, compliance will be necessary and will require the expenditure of significant capital. 

The decision to hire an outside engineering firm may be made at this time. Suggestions or 

directions as to how the project will be organized, who will be in charge, and how progress will 

be reported usually come out of this state. If a refiner has multiple refineries, representatives of 

each facility are usually involved in this stage in order to determine how the overall company 

should proceed and how each refinery will fit into the plan. By the time strategic planning is 

complete or nearly complete, each refinery will have a basic plan and direction in which to 

proceed. 

The length of time required for this stage varies by facility or company, depending on size, 

complexity, and the number of refineries. It is nearly impossible to precisely project how much 

time a specific refinery may need to complete this stage. However, our best estimate is that a 

small, single-facility refiner may need as few as three to six months; a large, complex, multiple 

facility refiner may need up to two years. Given that the rule was promulgated in late 2000 and 

that it was anticipated well before that, we expected and found that the refineries which currently 

produce 500 ppm sulfur diesel fuel have completed their strategic planning and intend to produce 

15 ppm sulfur diesel fuel. Additionally, as discussed below, several refiners have found it 

strategically wise to convert significant volumes of their high sulfur distillate production to 15 

ppm sulfur diesel fuel. 

b. Planning & Front-end Engineering – Deciding How to Do it 

Accurate and complete information is gathered during this stage so that preliminary 

process engineering work can proceed. Accurate feedstock and product characteristics are 

produced and initial contacts made with technology vendors to find the best, least expensive 

technology whereby feedstocks can be treated to produce finished products. With the help of 

vendors, decisions can be made regarding whether revamps of existing equipment are possible or 

whether new units will be necessary. Temperatures, pressures, and flowrates must be determined 

65

Highway Diesel Progress Review – June 2002 

early on, from which heat and material balances and process flow diagrams can be produced. 

Detailed engineering cannot begin until this stage is mostly complete. 

The length of time required for this stage varies by facility. We expect most refiners, 

regardless of size, to begin front-end engineering no later than early to mid 2003. Larger, more 

complex units will likely require detailed engineering before then. Indeed, we found that all but a 

few of the very small refiners have finished planning and are into front-end engineering, although 

perhaps 80 percent overall have yet to make final technology decisions. 

c. Detailed Engineering and Permits – Making the Arrangements 

Detailed engineering usually overlaps with the preceding and the following stages, but 

cannot begin in earnest until a hydrotreating technology has been chosen. The technology sets 

the operating conditions around which the rest of the unit is designed. Once that decision is final, 

various pieces of equipment, especially reactors, separators, and compressors specific to that 

technology, can be designed and ordered. As these plans are completed, structures can be 

designed to support them and piping and pumps designed to connect them at the specified 

flowrates. Heat exchangers and furnaces are designed to provide the necessary heat balance and 

instrumentation is designed to control the whole process. Eventually, piping and instrument 

diagrams and electrical drawings can be completed for the entire process. 

Once sufficient information is available, Notices of Intent to make changes to a refinery 

can be filed. This is critical and must be done in a timely manner, since actual construction cannot 

be started until construction permits are issued. 

The time required for detailed engineering and permits varies widely depending on the size 

and complexity of the unit or process. Given that we expect that Front-End Engineering would 

take about six months and Detailed Engineering and Permits about 11 months, we expect most 

refineries to begin this stage by late 2003 to early 2004. 

d. Procurement and Construction – Building It 

This stage necessarily overlaps with the preceding stage. Procurement includes 

purchasing long-lead items, as well as inventorying pipe, pumps, insulation, structural steel, a 

variety of valves, wire, and other consumables such as conduit, nuts, bolts, and gaskets. Longlead items such as furnaces, compressors, high-pressure pumps, and thick-walled, high-pressure 

vessels must be ordered early in a project, sometimes well before other plans are complete. 

Once permits are issued, construction can begin in earnest. Welding the stainless steel and 

alloy pipe used in most of the current hydrotreating technologies is time consuming. Once pipe 

arrives onsite, many contractors setup staging areas where long runs of pipe that do not require 

close length measurement can be fabricated for later use. Once concrete, vessels, furnaces, heat 

66

III. Progress Review of Desulfurization Technology 

exchangers, and pumps have been set, the previously welded long runs of pipe can be trimmed, 

flanges, valves, and instrumentation installed, and final connections made. Pressure testing, xraying, and other quality and workmanship inspections are carried out as construction proceeds. 

As runs and connections are completed, insulation can be installed and bare pipe painted. As 

heavy construction winds down, electrical and instrumentation connections are made and checkout is begun. Many instrumentation adjustments, such as loop-testing, cannot be made until liquid 

has been introduced and startup is progressing. 

Large, single unit projects can take as long as two to two and one-half years to build. 

Even minor problems can extend construction by as much as six months or more. Revamps can 

take less time, although tie-ins, changes to existing equipment, and the need to work within an 

operating facility can lengthen the time by several weeks or months. With careful planning, 

refiners can make critical tie-ins during planned shutdowns and turnarounds. Some facilities are 

located in warm winter climates where year-round construction is possible, while others must deal 

with winter construction which usually takes longer. Accessability to construction workers and 

the ease with which large vessels can be delivered can have a major effect on construction 

schedules. Construction workers, as a rule, tend to stay in areas where they can easily and in 

reasonable comfort work year-round. Also, since most large high-pressure vessels are currently 

manufactured overseas, it is easier for coastal refineries to receive them. While these types of 

issues do not prevent inland or less accessible refineries, typically located in colder regions of the 

country, from making necessary changes, they certainly must be planned for as delays almost 

always occur. We expect that even the smaller units should be under construction by no later than 

the end of October 2004. 

e. Commissioning and Startup – Making it Work 

Depending on the complexity of the project, commissioning and startup usually happen 

together. Some vendors have specific startup procedures for their technologies, whether for 

commissioning an entire process or for a catalyst alone A critical part of commissioning and 

startup is the Occupational Safety and Health Administration’s (OSHA) “Process Hazard 

Analysis”, a very complicated and time consuming, multi-part procedure that must be completed 

and signed-off on before startup can proceed. For this, accurate, final construction and as-built 

drawings, including complete piping and instrument diagrams, must be completed. A competent 

team of process and design engineers, environmental engineers, safety experts, and operation and 

maintenance personnel, among others, conduct a thorough, item-by-item, flow-by-flow, hazard 

analysis to determine whether everything, including equipment, instrumentation, and safety 

devices, was designed to adequately protect plant personnel and the environment. If anything is 

found to be unsafe or otherwise inadequate, it must be changed according to a rigorous set of 

OSHA guidelines. 

Depending on the size and complexity of the process, startup can take from three to six 

months. In spite of all the precautions and planning that will have gone into the project over the 

67

Highway Diesel Progress Review – June 2002 

preceding three or four years, most refiners judiciously plan for unforeseen events. Refiners in 

cold weather areas may delay a possible winter startup until perhaps early spring, but only if they 

fully expect the startup to go reasonably smoothly. If they delay too long, and run into startup 

problems, it is possible they may not startup on time. Additionally, some will need to provide for 

time to wash out tanks and old piping in preparation for 15 ppm sulfur product. Dealing with 15 

ppm sulfur diesel will also require changes in operating procedures as well as testing procedures. 

However, final introduction of new methods and procedures must wait until the fuel is actually 

produced. Refiners will need to account for and settle these issues well before the 15 ppm fuel 

must be delivered. 

Figure III.3, below, illustrates the estimated percentage of highway diesel fuel refiners that 

are at each of the stages described above. 

68

Jan. 1, 2002 

Jan. 1, 2003 

Jan. 1, 2004 

Jan. 1, 2005 

Jan. 1, 2006 

Plannin

g/Impl

ement

ation St

a

ge 

for 

P

roduci

ng L

o

w S

ulfur Dies

el F

u

el 

5% 5% 

1

Strategic 

Planning 

2

Planning & 

F ro nt-end Engineering 

3

D etailed E ngineering 

& P erm its 

4

P rocurem ent & 

C o nstru ctio n 

5

C o mm issio ning & 

Start-u p 

90% 0% 

Jan. 1, 2001 

Estimated Percent of Industry Currently at Given Stage 

III. Progress Review of Desulfurization Technology 

Estimated Percent of Industry Currently at Given Stage 

5% 90% 5% 0% 

1

Strategic 

Planning 

Clean Diesel I

ndependent R

e

view Panel 

2

Planning & 

F ro nt-end Engineering 

3

D etailed E ngineering 

& P erm its 

4

P rocurem ent & 

C o nstru ctio n 

5

C o mm issio ning & 

Start-u p 

Plannin

g/Impl

ement

ation St

a

ge 

for 

P

roduci

ng L

o

w S

ulfur Dies

el F

u

el 

1

2 

aJ

3 

aJ

4 

aJ

5 

aJ

6


n. 1, 200 

aJ

n. 1, 200 

aJ

n. 1, 200 

n. 1, 200 

n. 1, 200

n. 1, 200 

Figure III.3 Low Sulfur Diesel Fuel Progress Timeline 

2. Production Plans and Announcements 

As described above, most refiners will follow a common pathway to comply with the 

requirements of a regulatory program. The purpose of this section is to characterize the refining 

industry and to determine where refiners and their refineries are on the pathway toward 

compliance with the HD 2007 program. 

There are approximately 150 active refineries in the U.S. with a combined crude capacity 

of about 16.5 million bpd according to the Energy Information Administration (EIA) for 2001. 

Based on CBI data we obtained from EIA, approximately 110 refineries currently produce about 

2.5 million barrels per day of highway-compliant diesel fuel (that is, diesel fuel with a sulfur 

69

Highway Diesel Progress Review – June 2002 

content less than 500 ppm). Nearly one-half of these refineries are considered to produce only 

highway compliant diesel fuel. That is, 95 percent of their total distillate production has a sulfur 

content less than 500 ppm. The remaining refineries produce some highway and some offhighway distillate fuel. Approximately 30 refineries have no significant production of highway 

grade diesel fuel (less then 10 percent of their distillate production is highway-compliant diesel 

fuel) but some have indicated that they intend to enter the highway market by 2006. 

a. Public Announcements 

Part of our progress review was to track public announcements of specific refiner plans for 

producing 15 ppm diesel fuel. These refiners are ahead of schedule with respect to the program’s 

June 2006 implementation date. 

•	 Murphy Oil confirmed that it will produce not only EPA-compliant low sulfur gasoline, 

but also approximately 25,000 bbl/day of 15 ppm sulfur diesel fuel when its Greener Fuel 

Project at its Meraux, Louisiana refinery is completed in mid-2003. The refinery's decision 

to produce 15 ppm on-highway diesel prior to 2006 will be based on customer demand 

and market economics.29 

•	 Holly announced a new hydrotreater project at its Navajo refinery in New Mexico that will 

allow it to produce low sulfur gasoline and make it “easier” to produce 15 ppm diesel fuel 

in advance of 2006.30 

•	 Flint Hills (formerly Koch) announced upgrades to its Corpus Christi, Texas refinery that 

are designed to meet upcoming low-sulfur gasoline standards. The upgrades will help 

create “synergies” for the eventual production of 15 ppm diesel fuel.

31 

•	 Chevron Products Company has confirmed that desulfurization capacity upgrades at its 

Pascagoula, Mississippi refinery will make the refinery capable of producing at least 

25,000 bbl/day of 15 ppm on-highway diesel fuel by mid-to-late 2003. The refinery's 

decision to produce 15 ppm on-highway diesel prior to 2006 will be based on customer 

demand and market economics.32 

•	 Frontier Oil (a small refiner) announced that it will delay 15 ppm diesel fuel compliance 

until 2010 at their Cheyenne, Wyoming refinery and comply with the low sulfur gasoline 

rule on time. The company will comply by June 2006 with the low sulfur diesel fuel 

program and delay low sulfur gasoline compliance until 2010 at its El Dorado, Kansas 

refinery.

33 

70

III. Progress Review of Desulfurization Technology 

b. Other Refiner Indications 

i. Small Refiner Indications 

Twenty-one refineries owned by 17 refining companies have applied for and/or been 

approved for small refiner status under the HD 2007 program. Of these 21 refineries, four have 

indicated their intent to use the 500 ppm Option, six have indicated their intent to use the Small 

Refiner Credit Option, eight have indicated their intent to use the Diesel/Gasoline Compliance 

Date Option, and just four refineries are undecided. This information is summarized in Table 

III.2, below. Note that some double-counting occurs as the categories are not mutually exclusive. 

Because some refineries have indicated their intent to use more than one option, the total number 

of refineries indicated in the table below is greater than 21. 

Table III.2 Intended Small Refiner Compliance Options by Number of Refineries 

Option Description Number of Refineries 

A. 500 ppm Option 4 

B. Credit Option 6 

C. Diesel/Gasoline Compliance Date Option 8 

Undecided 4 

Total 22* 

* Some double-counting occurs as the categories are not mutually exclusive. Because some refineries 

have indicated their intent to use more than one option, the total number of refineries indicated in the 

table below is greater than 21. 

ii. GPA Refiner Indications 

Thirty-five refining facilities owned by 15 companies have indicated their intent to produce 

GPA gasoline under the low sulfur gasoline program. Nearly one-third of these refining facilities 

have indicated their intent to take advantage of the GPA refiner provision under the HD 2007 

rule. As described above, this provision will provide them two additional years to comply with 

the national gasoline standards if they produce all of their highway diesel fuelw at the 15 ppm 

specification beginning June 1, 2006. 

w As described in the preamble to the final rule, a refinery must also maintain a production volume of 15 

ppm highway diesel fuel that is at least 85 percent of the baseline highway diesel fuel volume that was produced at 

the refinery during 1998 and 1999. 

71 
Highway Diesel Progress Review – June 2002 

iii. Hardship Approvals 

Under the low sulfur gasoline program, four refineries pursued hardship waivers. Three of 

these applications were approved last year and the final one was approved this year. Hardship 

applications under the highway diesel program were due June 1, 2002. A few applications were 

received and we will be reviewing them over the next few months. 

c. Conversion of Off-highway to Highway Diesel Fuel Production 

In addition to tracking the plans of current highway diesel producers to comply with the 

HD 2007 program, we are also tracking the plans of other refiners who currently produce no to 

very little highway fuel to enter the highway market. Several refineries have already indicated that 

they will convert most, if not all, of their current high sulfur off-highway diesel fuel (which 

averages about 3000 ppm) to 15 ppm sulfur diesel by 2006. At present, we expect at least nine 

refineries to convert an aggregate volume of about 66,000 bbl/day of high-sulfur diesel to 15 ppm 

sulfur diesel fuel. (Most of these nine refineries have indicated their intent to take advantage of 

the small refiner, GPA, or hardship provisions offered under the program.) This represents only 

those refineries that have completed their initial planning and preliminary engineering. Given that 

only a few refineries have progressed beyond initial planning, we expect an increase in the number 

of refineries that expect to expand their low sulfur diesel production volumes. 

d. Summary of Indicated Production Plans and Announcements 

The following table describes projects, plans, and commitments already made by refiners 

to produce 15 ppm sulfur diesel fuel by the June 2006 program compliance date. Note that some 

double-counting in the “Number of Refineries” column occurs as the categories are not mutually 

exclusive. However, the “Highway Diesel Fuel Volume for 2000" and “Highway Diesel Fuel 

Volume %” columns exclude double-counting. 

72

III. Progress Review of Desulfurization Technology 

Table III.3 Summary of Refinery Production Plans and Announcements 

Number of 

Refineries 

Category 

Highway Diesel Fuel 

Volume for 2000 

(000 bbls/day) 

Highway Diesel Fuel 

Volume % 

8 Small (Option C) 91 3.6 % 

12 GPA 114 4.5 % 

9 

Other Hwy Diesel Refinery 

Indications and Public 

Announcements 

118 4.7 % 

9 Conversion of Off-hwy to 

15 ppm Sulfur Hwy Diesel Fuel 

38 Total of All Categories 323 12.8 % 

e. U.S. Refinery Construction Projects 

As part of our progress review, we have also been tracking crude expansion projects as 

well as hydrotreating, hydrocracking, and hydrogen capacity projects. We included this 

information in our review to demonstrate that the production of distillate fuel, distillate feed 

stocks, and other finished products such as gasoline, is increasing as a result of refineries adding 

capacity. In addition to planning for low sulfur diesel fuel, refiners will likely continue to expand 

their capacity over time to meet ever increasing fuel demand. As we projected in the HD 2007 

rule, this also appears to be occurring. 

73

Highway Diesel Progress Review – June 2002 

Table III.4 Crude Expansion Projects at U.S. Refineries. 

CRUDE 

Present Crude 

Refinery Location State Capacity Expansion Projected Completion 

(bpcd) (bpcd) 

Alon Big Springs TX 61,000 4,000 By 2002 

Citgo Lake Charles LA 333,000 100,000 2002 

Navajo Refining Artesia NM 60,000 20,000 1st phase by end-2003 

Murphy Oil USA Meraux LA 100,000 25,000 Mid-2003 

Phillips Borger TX 130,000 20,000 2002 

Valero* Texas City TX 20,000 

Williams Energy Memphis TN 175,000 20,000 By March 2002 

*Announced it wants to spend additional profits from merger with UDS to expand refineries 

Table III.5 Hydrotreating and Hydrocracking Projects at U.S. Refineries. 

HYDROTREATING & HYDROCRACKING 

Company Location State Hydrocracking Hydrotreating Projected Completion 

ExxonMobil 

Flint Hills 

MAP LLC 

NCRA 

Shell 

Valero 

Baytown 

Corpus Christi 

Delaware City 

McPherson 

Los Angeles 

Puget Sound 

Port Arthur 

Deer Park 

Norco 

Convent 

Texas City 

TX 

TX 

DE 

KS 

CA 

WA 

TX 

TX 

LA 

LA 

TX 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

x 

By 2002; revamp 

May 2001 

2001 

2006 

By 2003; expansion 

By 2003; expansion 

By 2003 

By 2003 

By 2003 

By 2003 

2001; expansion 

74

III. Progress Review of Desulfurization Technology 

Table III.6 Hydrogen Plant Projects at U.S. Refineries. 

HYDROGEN 

Company Location State Hydrogen Projected 

MMSCF Completion 

NCRA McPherson KS 25 2006 

Valero Texas City TX 2001 

Our progress review indicates that the vast majority of refiners are exactly where we 

would expect them to be relative to the June 2006 compliance date for the HD 2007 program. 

These refiners have decided that they will comply with the program and are now in the midst of 

figuring out how to best do so. We are very encouraged by the actions some refiners have 

already taken in terms of announcing specific plans for low sulfur diesel fuel production. 

Thus, the refining industry is where we anticipated it to be at this point in time. Moreover, 

some refining companies are ahead of schedule and will be capable of producing significant 

quantities of 15 ppm sulfur diesel fuel as early as next year. 

75

Highway Diesel Progress Review – June 2002 

76

IV. Conclusions 

IV. Conclusions 

The Agency has completed a comprehensive technical review of progress by 1) the 

manufacturers of diesel engines and emission control systems in developing technology to reduce 

engine exhaust pollutants, and 2) the petroleum refining industry in developing and demonstrating 

technologies to effectively lower the sulfur level of diesel fuel. From this review, we can conclude 

the following: 

Engine Emission Control Technologies 

•	 Every major engine manufacturer expects to be able to comply with effective 

standards in 2007. 

• The CDPF technology is rapidly maturing and will be broadly applicable by 2007. 

•	 Catalyzed diesel particulate filters (CDPFs) are already being applied where 15 

ppm sulfur diesel fuel is available. 

•	 NOx adsorbers are improving in effectiveness and durability at a rapid pace. We 

are confident that they will be available for use to comply with the 2007 emission 

standards. 

•	 EPA intends to continue to monitor progress to develop the NOx adsorber catalyst 

technology and will report out again on its progress in a second biennial review by 

December 31 of 2004. 

Diesel Fuel Desulfurization Technologies 

•	 The 15 ppm diesel fuel sulfur standard was established based on the use of 

conventional diesel desulfurization technologies. These technologies have been 

commercially proven and refineries are basing their refinery changes for producing 

15 ppm diesel fuel on them. 

•	 Diesel fuel refineries are well positioned to make firm plans for 2006 

implementation. 

•	 Virtually all refiners are already in the stage of planning their approach for 

compliance with the 2006 fuel sulfur standard. 

• New lower cost desulfurization technologies are being developed. 

77

Highway Diesel Progress Review – June 2002 

•	 These new technologies could prove to be valuable for small refineries that can 

delay implementation of the new fuel under flexibilities provided in the rulemaking. 

•	 The refining industry appears to be where we would have anticipated it to be at 

this point in time relative to the June 2006 compliance date of the HD 2007 

program. 

•	 Some refiners are ahead of schedule and will be capable of producing significant 

volumes of 15 ppm sulfur diesel fuel as early as next year. 

78

Appendix A: List of Acronyms 

Appendix A: List of Acronyms 

ABT Averaging, Banking, and Trading


APBF – DEC Advanced Petroleum Based Fuels – Diesel Emission Control


CAA or the Act Clean Air Act


CDPF Catalyzed Diesel Particulate Filter


CTR Credit Trading Region


DASL Diesel Aftertreatment Sensitivity to Lubricants


EIA Energy Information Administration


EPA or the Agency U.S. Environmental Protection Agency


DECSE Diesel Emission Control Sulfur Effects


DEOAP Diesel Engine Oil Advisory Panel


DOE Department of Energy


DPNR Diesel Particulate NOx Reduction


FACA Federal Advisory Committee Act


FR Federal Register


GPA Geographic Phase-in Area


HDE Heavy-duty Engine


HDV Heavy-duty Vehicle


LTC Low Temperature Combustion


MECA Manufacturers of Emission Control Association


NAAQS National Ambient Air Quality Standards


NMHC Non-methane Hydrocarbons


NOx Oxides of Nitrogen


NPRM Notice of Proposed Rulemaking


NTE Not-to-exceed


NVFEL National Vehicle and Fuel Emissions Laboratory


OEM Original Equipment Manufacturer


PADD Petroleum Administrative Districts for Defense


PM Particulate Matter


ppm Parts per Million


RIA Regulatory Impact Analysis


SET Supplemental Emission Test


79

Highway Diesel Progress Review – June 2002 

SO2 Sulfur Dioxide 

SOx Oxides of Sulfur 

SwRI Southwest Research Institute 

TCO Temporary Compliance Option 

VOC Volatile Organic Compound 

80

Appendix B: HD 2007 Progress Review Meetings 

Appendix B: HD 2007 Progress Review Meetings 

Meetings Related to EPA’s HD 2007 Progress Review (Engines and Vehicles) 

Caterpillar Inc.


Corning Incorporated


Cummins Incorporated


DaimlerChrysler


Detroit Diesel Corporation (DDC)


Delphi / ASEC


Department of Energy (DOE)


EmeraChem


Engelhard Corporation


Ethyl Corporation


Ford Motor Company


General Motors Corporation


Hino Motors LTD.


International Truck and Engine Corp.


Isuzu Motors LTD.


Japan Automobile Manufacturers Assoc.


Japan Ministry Land Infrastructure Transport


Johnson Matthey


Mack/Volvo/Renault


Manufacturers Emission Control Assoc.


Mitsubishi Motors Corporation


NGK


Nissan Diesel Motor Company


Nissan Motor Company, LTD.


OMG


PSA/Peugeot


Toyota Motor Corporation


Volkswagen AG


81

Highway Diesel Progress Review – June 2002 

Meetings and Conference Calls Related to 

EPA’s HD 2007 Progress Review (Technology Vendors and Refiners) 

Technology Vendors 

Akzo Nobel 

Criterion Catalysts 

Halder Topsoe 

Refining Companies 

Alon USA LP


Atofina Petrochemicals


Big West Oil Company


BP Amoco PLC


Cenex Harvest States Coop


Chevron


Citgo


Coastal Refining


Conoco


Countrymark Coop Incorporated


ExxonMobile


Farmland Industries


Frontier Refining


Equilon/Shell


Gary Williams Energy Corporation


Giant Refining


Koch


Hunt Refining


IFP


UOP


UniPure


Marathon Ashland


Montana Refining


Murphy Oil Corporation


Navajo Refining


NCRA


Phillips Tosco


Placid Refining


Premcor Refining


Silver Eagle


Sinclair Oil Corporation


Somerset Refinery Incorporated


Sunoco


Tesoro


United Refining


Valero-UDS


Western Refining


Williams


Wyoming Refining


82

Appendix C: Literature Review 

Appendix C: Literature Review 

Mayo, S., Brevoord, E., Plantenga, F., Gudde, N., and Hoekstra, G.; ULSD in Real Life: 

Commercial Performance of Stars and Nebula Technology; AM-02-38; 2002 NPRA Annual 

Meeting; San Antonio, TX. 

McIntosh, K., Petrinec, B., Hacker, S., DeBerry, K. Jr.; Crystasulf : A Process That Removes 

Both H2S and Light Hydrocarbons From HDS Hydrogen Recycle Streams; AM-02-13; 2002 

NPRA Annual Meeting; San Antonio, TX. 

Torrisi, S., DiCamillo, D., Remans, T., Street, R., Svendsen, J., Criterion Catalyst & 

Technologies; Proven Best Practices for ULSD Production; AM-02-35; 2002 NPRA Annual 

Meeting; San Antonio, TX. 

Lamourelle, A., McKnight, J., Nelson, D.; Clean Fuels: Route To Low Sulfur Aromatic Diesel; 

AM-01-28; 2001 NPRA Annual Meeting; New Orleans, LA. 

Stynes, P., Shepard, T., Thompson, M., Kidd, D.; Innovation Key To New Technology Project 

Success Phillips S Zorb Becomes Low Sulfur Gasoline Solution; AM-01-43; 2001 NPRA Annual 

Meeting; New Orleans, LA. 

Vaarkamp, M., Chung-Ming, C., Duijndam, B.; Upgrading Light Cycle Oil to Diesel Using The 

Engelhard-Washington Redar Process; AM-01-23; 2001 NPRA Annual Meeting; New Orleans, 

LA. 

Shiflett, W., Criterion Catalyst & Technology; The Drive To Lower And Lower Sulfur: 

Criterion’s New Catalyst Help Refiners Tackle Sulfur; AM-01-29; 2001 NPRA Annual 

Meeting; New Orleans, LA. 

Levy, R., Rappas, A., UniPure Corp., Nero, V., DeCanio, S., Texas, Inc.; Unipure’s ASR-2 

Diesel Desulfurization Process: A Novel, Cost-Effective Process For Ultra-Low Sulfur Diesel; 

AM-01-10; 2001 NPRA Annual Meeting; New Orleans, LA. 

Mayo, S., Leliveld, B., Plantenga, F., Miyauchi, Y.; Elegant Solutions For Ultra Low Sulfur 

Diesel; AM -01-09; 2001 NPRA Annual Meeting; New Orleans, LA. 

Plain, C., Duee, D., Harter, I.; Deep Hydrodesulfurization: The Importance of Optimized Flow 

Distribution; AM-01-47; 2001 NPRA Annual Meeting; New Orleans, LA. 

Blake, E., Sanderson, W., Birch, C.; Ultra-Low Sulfur Fuels In Europe Issues And Impacts; AM01-67; 2001 NPRA Annual Meeting; New Orleans, LA. 

83

Highway Diesel Progress Review – June 2002 

Pinto, R., Reid, T.; Leverage Your Assets: Hydroprocessing And FCC Solutions For Lowering 

The Cost of Clean Fuels; AM-01-08; 2001 NPRA Annual Meeting; New Orleans, LA. 

Avidan, A., Cullen, M.; Sulphco-Desulfurization Via Selective Oxidation-Pilot Plant Results And 

Commercialization Plans; AM-01-55; 2001 NPRA Annual Meeting; New Orleans, LA. 

Johnson, B., Kidd, D. Greenwood, G., Slater, P.; Application Of Phillip’s S Zorb Process To 

Distillates–Meeting The Challenge; AM-01-14; 2001 NPRA Annual Meeting; New Orleans, LA. 

84

References 

References


1.	 Diesel Emission Control-Sulfur Effects Program, Phase I Interim Data Report No. 1, 

August, 1999 EPA Docket A-99-06. 

Diesel Emission Control-Sulfur Effects Program, Phase I Interim Data Report No. 2, 

October, 1999, Air Docket A-99-06. 

Diesel Emission Control Sulfur Effects (DECSE) Program - Phase I Interim Data Report 

No. 3: Diesel Fuel Sulfur Effects on Particulate Matter Emissions, November 1999, EPA 

Docket A-99-06 

Diesel Emission Control Sulfur Effects (DECSE) Program - Phase I Interim Data Report 

No. 4, Diesel Particulate Filters-Final Report, January 2000, Air Docket A-99-06 

Diesel Emission Control - Sulfur Effects (DECSE) Program Phase II Summary Report: 

NOx Adsorber Catalysts, October 2000 EPA Docket A-99-06. 

Copies of all of these reports can be found at www.ott.doe.gov/decse. 

2.	 Letter from Thomas Gross, Deputy Assistant Secretary for Transportation Technologies 

Energy Efficiency and Renewable Energy US DOE, to Margo Oge, Director US EPA 

Office of Transportation and Air Quality, May 3, 2002. 

3. Ronny Allanson, Phillip Blakeman, Barry Cooper, Howard Hess, Peter Silcock, Andrew 

Walker, “Optimising the Low Temperature Performance and Regeneration Efficiency of 

the Continuously Regenerating Diesel Particulate Filter (CR-DPF) System” March 2002 

SAE 2002-01-0428 

4.	 http://www.psa-peugeot-citroen.com/frontvalide/base_html/modules/diesel/anglais/frame_ 

fap.html 

5. Koichiro Nakatani, Shinya Hirota, Shinichi Takeshima, Kazuhiro Itoh, Toshiaki Tanaka, 

and Kazuhiko Dohmae, “Simultaneous PM and NOx Reduction System for Diesel 

Engines.”, SAE 2002-01-0957, SAE Congress March 2002. 

6. C. LeTavec, J. Uihlein, K. Vertin, S. Chatterjee, S. Wayne, N. Clark, M. Gautam, G. 

Thompson, D. Lyons, K. Hallstrom, K. Chandler, T. Coburn, “Year-Long Evaluation of 

Trucks and Buses Equipped with Passive Diesel Particulate Filters,” March 2002, SAE 

2002-01-0433. 

85

Highway Diesel Progress Review – June 2002 

7. S. Hashimoto, Y. Miyairi, T. Hamanaka, R. Matsubara, T. Harada, and S. Miwa, “SiC and 

Cordierite Diesel Particulate Filters Designed for Low Pressure Drop and Catalyzed, 

Uncatalyzed Systems.” SAE 2002-01-0322, March 2002. 

8. I. Hachisuka, T. Yoshida, H. Ueno, N. Takahashi, A. Suda, M. Sugiura, “Improvement of 

NOx Storage-Reduction Catalyst,” March 20002 SAE 2002-01-0732. 

9. J. Hepburn, E. Thanasiu, D. Dobson, W. Watkins, “Experimental and Modeling 

Investigations of NOx Trap Performance”, SAE 962051, 1996. 

10.	 Dou, Danan and Balland, Jean, “ Impact of Alkali Metals on the Performance and 

Mechanical Properties of NOx Adsorber Catalysts”, SAE 2002-01-0734, 2002. 

11. HD 2007 RIA Chapter III available at http://www.epa.gov/otaq/diesel.htm#regs 

12. Diesel Emission Control Sulfur Effects (DECSE) Program Phase II Summary Report: 

NOx Adsorber Catalysts, October 2000, Air Docket A-99-06. 

13.	 Dearth, M. et al., “Sulfur Interaction with Lean NOx Traps: Laboratory and Engine 

Dynamometer Studies”, SAE 982595, 1998. 

14. HD 2007 RIA Chapter III available at http://www.epa.gov/otaq/diesel.htm#regs 

15.	 Asanuma, T. et al., “Influence of Sulfur Concentration in Gasoline on NOx StorageReduction Catalyst, SAE 1999-01-3501, 1999. 

16.	 Dearth, M. et al., “Sulfur Interaction with Lean NOx Traps: Laboratory and Engine 

Dynamometer Studies”, SAE 982595, 1998. 

17. Diesel Emission Control Sulfur Effects (DECSE) Program Phase II Summary Report: 

NOx Adsorber Catalysts, October 2000, Air Docket A-99-06. 

18. HD 2007 RIA Chapter III available at http://www.epa.gov/otaq/diesel.htm#regs 

19. C. Schenk, J. McDonald, B. Olson, “High-Efficiency NOx and PM Exhaust Emission 

Control for Heavy-Duty On-Highway Diesel Engines,” SAE 2001-01-1351. 

20. C. Schenk, J. McDonald, C. Laroo, “High-Efficiency NOx and PM Exhaust Emission 

Control for Heavy-Duty On-Highway Diesel Engines - Part Two,” SAE 2001-01-3619. 

21.	 Toyota Press Release July 25, 2000 “Revolutionary Diesel Aftertreatment System 

Simultaneously Reduces Diesel Particulate Matter and Nitrogen Oxides.” 

86

References 

22.	 Toyota Press Release March 6, 2002 “Toyota to Start DPNR Monitoring Program in 

Europe, Advanced Diesel Emissions Purification System to Be Fitted on Avensis” 

23.	 S. Sasaki, T. Ito, S. Iguschi, “Smoke-less Rich Combustion by Low Temperature 

Oxidation in Diesel Engines,” 9th Aachen Colloquium Automobile and Engine Technology 

2000. 

24. Koichiro Nakatani, Shinya Hirota, Shinichi Takeshima, Kazuhiro Itoh, Toshiaki Tanaka, 

and Kazuhiko Dohmae, “Simultaneous PM and NOx Reduction System for Diesel 

Engines.”, SAE 2002-01-0957, SAE Congress March 2002. 

25.	 S. Sasaki, T. Ito, S. Iguschi, “Smoke-less Rich Combustion by Low Temperature 

Oxidation in Diesel Engines,” 9th Aachen Colloquium Automobile and Engine Technology 

2000. 

26.	 Stanglmaier, Rudolf and Roberts, Charles “Homogenous Charge Compression Ignition 

(HCCI): Benefits, Compromises, and Future Engine Applications”. SAE 1999-01-3682, 

1999. 

27. Kimura, Shuji, et al., “Ultra-Clean Combustion Technology Combining a LowTemperature and Premixed Combustion Concept for Meeting Future Emission 

Standards”, SAE 2001-01-0200, 2001. 

28.	 S. Sasaki, T. Ito, S. Iguschi, “Smoke-less Rich Combustion by Low Temperature 

Oxidation in Diesel Engines,” 9th Aachen Colloquium Automobile and Engine Technology 

2000. 

29. Diesel Fuel News, Feb. 4, 2002, p. 3 

30. ibid. 

31. ibid. 

32. ibid. 

33. OPIS Newsletter, Sept. 10, 2001 

87