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World Headquarters 

One American Road 

Dearborn, MI 48126-2701 USA 

November 19, 2013 

Michael Olechiw Paul Machiele 

Director, Light-Duty Vehicles and Small Engines Center Director, Fuels Center 

Assessment and Standards Division Assessment and Standards Division 

U.S. EPA Office of Transportation and Air Quality U.S. EPA Office of Transportation and Air Quality 

2000 Traverwood Drive 2000 Traverwood Drive 

Ann Arbor, MI 48105 Ann Arbor, MI 48105 

Attention: Docket No. EPA-HQ-OAR-2011-0135 

Subject: Fuel Quality Changes Needed to Meet Tier 3 Emission Standards and Future Greenhouse Gas 

Requirements 

Dear Mr. Michael Olechiw and Mr. Paul Machiele: 

This letter and the attached documents constitute supplemental comments of Ford Motor Company (“Ford’) on the 

Environmental Protection Agency’s (“EPA’s”) proposed “Tier 3” regulations. Please add these comments to Docket 

No. EPA-HQ-OAR-2011-0135 so that they are included as part of the administrative record for this rulemaking. 

These comments further address the need to decrease market fuel sulfur concentrations to a maximum of 10 ppm. 

The attachments to this letter include data and information demonstrating the adverse effects of fuel sulfur on 

exhaust emission aftertreatment devices planned for use to meet future proposed Tier 3 emission regulations. The 

attachments are as follows: 

1. Sulfur Effects on Gasoline Exhaust Emissions (previously presented to EPA in May 2011)

2. Tier 3 Sulfur Test Program (data recently generated in 2013)

Summary of Ford’s Position 

In setting emission standards for motor vehicles, Ford believes it is essential for regulators to address fuels and 

vehicles as a system. The ability to deploy emissions control technologies on a vehicle, in order to meet specified 

emission standards, often depends on the quality of the fuel to be used in the vehicle. It is critical that EPA use a 

systems approach in setting the proposed Tier 3 exhaust and evaporative emission regulations, as well as future fuel 

economy and greenhouse gas standards. 

EPA is a global leader in vehicle emissions reductions. However, improvements in fuel quality in the U.S. have not 

kept pace with advances in other developed countries, which have demonstrated the capability to provide gasoline 

with 10 ppm sulfur to the retail marketplace. 

Ford believes that, based on the data presented here and elsewhere, reductions in sulfur content in gasoline to a 

maximum of 10 ppm are needed for the following reasons: 

 Aftertreatment systems are expected to experience reduced efficiency, resulting in increased 

tailpipe emissions, when exposed to fuel containing higher sulfur content 

 New advanced lean-burn technology will be inhibited if fuel sulfur content is not controlled to 

10 ppm 
Mr. Michael Olechiw 

Mr. Paul Machiele 

November 19, 2013 

Page 2/2 

Summary of Attachments 

Attachment 1 is a presentation titled, “Sulfur Effects on Gasoline Exhaust Emissions.” The presentation includes 

data addressing the following topics: 

• Fuel sulfur content in the U.S. and worldwide 

• The harmful effects of fuel sulfur on catalyst efficiency 

• The contribution of fuel sulfur to particulate emissions 

• The adverse impacts of fuel sulfur on lean NOx storage efficiency 

Attachment 2 is a summary of a recent test program comparing the exhaust emissions of a vehicle operating on 30 

ppm sulfur gasoline with the exhaust emissions of the same vehicle operating on 10 ppm gasoline. The test results 

show that NMHC + NOx emissions were 45% higher on the vehicle using the high-sulfur fuel, and the emissions 

increase is statistically significant at a 95% confidence level. The test is further evidence that fuel containing 30 

ppm sulfur is not compatible with current and future proposed emission standards, or with the technology necessary 

to meet such standards. 

Conclusion 

These supplemental comments add important data to the record that should be considered by EPA as it sets limits on 

the sulfur content of gasoline. We believe that a 10 ppm sulfur limit is both appropriate and essential based on the 

data in these comments, as well as other data and information presented by the Alliance of Automobile 

Manufacturers and many of our competitors in the auto industry. 

We note that, in addition to sulfur reductions, there are other fuel quality improvements needed to enable automobile 

manufacturers to achieve future standards imposed on motor vehicles. For example, reduced summer gasoline vapor 

pressure is needed to assist in achieving Tier 3 evaporative emission regulations, and an increase in the minimum 

gasoline octane rating is needed to enable manufacturers to achieve future fuel economy requirements and 

reductions in greenhouse gases. We urge EPA to take action on all fuel quality improvements necessary to support 

upcoming vehicle standards. 

If there are specific questions regarding these recommendations or any clarifications or comments provided within 

the documents, please feel free to contact me at 313-594-2916 for further discussions. Thank you for including this 

material in the Tier 3 docket. 

Sincerely, 

Dominic M. DiCicco 

Manager, Environmental Policy and Fuel Quality 

Sustainability and Vehicle Environmental Matters 

cc via email: Mr. Joseph McDonald, Senior Engineer, U.S. EPA/OTAQ/ASD 

 Mr. Antonio Fernandez, Senior Engineer, U.S. EPA/OTAQ/ASD 
ATTACHMENT 1
Sulfur Effects on Gasoline Ex

Emissions

with Advanced Catalyst Formulations

Ford / EPA Technical Discussion

Presented: May 10, 2011

Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Outline

I. Gasoline Sulfur

a. Market Fuel

II. Three-way Catalysts

a. LEV I & pre-Tier 2b. Laboratory Tier 2c. Vehicle PZEV Testing

III. Particulate MatterIV. Lean NOx Traps

a. Mechanismb. Storage Efficiency

* NOTE: The data in this presentation are a compilation of existing information and summaries. 
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Market Fuel – Sulfur – U.S. Summer 2010

Present EPA max. 80ppm

Ford Proposed max. of 10 ppm cap

Present EPA

average 30ppm

ARB CAP30ppm

ARto 

Source: Alliance of Automobile Manufacturer Fuel Survey
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Market Fuel – Sulfur – Worldwide

U.S. Eu

Canada 

10 ppm 

Source: Alliance of Automobile Manufacturer Fuel Survey

SGS Worldwide Fuel Survey
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Three-Way Catalysts (TW
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

HC

CO/NOx

Fuel Sulfur

% Catalyst Efficiency

Sulfur decreases conversion efficiency 

pre-Tier 2 technology

Effects of Fuel Sulfur – LEV I Catalyst Technolo
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Fuel Sulfur, ppm

%CO/NOx Catalyst Efficiency

Sulfur effects on varying 

catalyst formulations (differ

precious metal types)

Effects of Fuel Sulfur – Tolerance of Catalyst Fo
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Laboratory Catalyst EvaluationObjective: Evaluation of catalyst formulations and determof sulfur effectsConducted: At the Ford Research and Innovation Center Dearborn, MIProcess: Samples evaluated in a setting designed to rep

typical inlet catalyst exhaust environment encountered duvehicle operation (exhaust constituents, temperature, Air/FSpace Velocity, etc...)*

Effects of Fuel Sulfur – Tier 2 Catalyst Technolo
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Rich Lean

HC

CO NOx

% Catalyst Efficiency

Lambda

TIER 2 / LEV II Technology

Catalyst Efficiency Evaluation – Air/Fuel Sweep

HC, 3NOx

HC, 0 

CO, 3NOxCO, 0 
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Rich Lean

0 ppm vs. 30 

HC

NOx

% Catalyst Efficiency

Lambda

1. Catalyst E

criteria em(HC, CO, 

TIER 2 / LEV II Technology

Catalyst Efficiency Evaluation – Air/Fuel Sweep 

HC, 3NOx

HC, 0 

CO, 3NOxCO, 0 

CO
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Rich Lean

CO-NOx Crossover

0 ppm vs. 30 

HC

CO

NOx

% Catalyst Efficiency

Lambda

1. Catalyst E

criteria em(HC, CO, 

2. CO/NOx C

declines

TIER 2 / LEV II Technology

Catalyst Efficiency Evaluation – Air/Fuel Sweep 

HC, 3NOx

HC, 0 

CO, 3NOxCO, 0 
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Rich Lean

CO-NOx Crossover

0 ppm vs. 30 

HC

CO

NOx

% Catalyst Efficiency

Lambda

1. Catalyst E

criteria em(HC, CO, 

2. CO/NOx C

declines

3. Window o

becomes 

Sulfur 

catalyst 

Swe

perform

TIER 2 / LEV II Technology

Catalyst Efficiency Evaluation – Air/Fuel Sweep 

HC, 3NOx

HC, 0 

CO, 3NOxCO, 0 
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Samples provided below are technologies in production and/or plannin Tier 2 vehicles.

Data show that 30 ppm Sulfur reduces

Catalyst Efficiency in Tier 2 catalyst technol

Catalyst CO/NOx InEfficiency Data – Air/Fuel Sw

Example of Sample #3:100% Conversion Efficiency = 0% Inefficiency; thus, 98.7 % conv. Eff. = 1.3% Inefficiency If the vehicle engine-out catalyst feedgas emission level is 2.0 g/mile...

98.7% conv. Eff. (1.3% inefficiency) results in 0.026 g/mile emissions97.1% conv. Eff. (2.9% inefficiency) results in 0.058 g/mile emissions

Finally, calculating the increase in emissions due to sulfur results in [(0.058 – 0.026)/0.026] * 100 = 

400cpsi 900cpsi
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Including the 250ppm Sulfur 

data appears to indicate a 

different function below 30ppm

CO/NOx Crossover

Linear

Interpolation

Extrapolation

Catalyst CO/NOx InEfficiency Data – Air/Fuel Sw
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

18%

17%

48%

78%

44%

26%

Using % valuchart rchange 

InEfficiency region below 30 ppm Sulfur

~44 % Reduction in Emissions when Sulfur 

reduced from 30 ppm to 5 ppm Sulfur

Catalyst CO/NOx InEfficiency Data – Air/Fuel Sw
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

2009MY 2.4L Malibu PZEV; 33 ppm sulfur vs 3 ppm sulfurExhaust aftertreatment system uses one close-coupled & one under floor co

Catalyst NOx mg/mile Data 

– from SAE 2011-01-0300

43% Reduction

No NOx creep & lower NOx emissions w/

Prep Protocol #1 Prep Protocol #2 Prep Protocol #1
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Particulate Matter
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

• Sulfur in fuel results in sulfur

in the exhaust stream

• Sulfur in the exhaust can oxidize

into sulfates

• Sulfates contribute to the

fraction of particulate matter in 

the environment

Particulate matter mass originating from sulfates resulti

gasoline containing higher levels of sulfur need consid

“Particulate 

CondensedHydrocarbons

Metal / Inorganic Ash

Sulfur in fuel contributes to Particula

Matter (PM) mass

Market Fuel Quality – PM due to Sulfur
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Lean NOx Traps
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

Conventional TWC and NOx Reduction

The conventional TWC is ineffective for N

reduction under lean conditions

%NOx Conversion Efficiency

10 20 30 

0

stochiometric operation 20406080

100

Lean PFI Stratified lea

Homogeneous lean 

Stochiometric operation

A/F Ratio
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

The Lean NOx trap suffers due to sulfur pois

Sulfur attachused by NOxwith the Leatrapping func

Lean NOx Trap – Sulfur Poisoning Mechanism
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

0

102030405060708090

100

0 10 20 30 40 50 60 70 

Hours

Avg NOx Storage Efficiency (%) @ 1 Minute ~ 200 ppm fuel sulfur level ~ 40 pp

~ 100 ppm fuel sulfur level

Lean NOx Trap – Sulfur Poisoning

80 

> 95% Effi

required for T
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

• According to market fuel surveys, leading countries have 

10 ppm maximum sulfur for gasoline

• Sulfur in gasoline has been shown to poison catalysts res

reduced catalytic conversion efficiency

• Sulfur is expected to continue to affect all precious metal c

formulations (Pd-only, Pd-Rh, Tri-metal, Pt-Rh) – i.e. No CSolution

• Laboratory and independent vehicle testing show >40% re

NOx emissions when decreasing sulfur from 30 ppm to 5 

• Sulfur in gasoline can transition into sulfates which contrib

fraction of PM in the environment

• Very low levels of sulfur are needed to avoid sulfur poison

Lean NOx Traps resulting in NOx storage efficiencies belorequired targeted levels

Conclusion

Sulfur at 10 ppm maximum (or lower) is 

recommended & supported by the d
Submitted to: EPA Tier 3 Docket No. EPA-HQ-OAR-2011-

THANK YOU!
ATTACHMENT 2
Ford Tier 3 Sulfur Test Program November 19, 2013 

Docket No. EPA-HQ-OAR-2011-0135 

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Tier 3 Sulfur Test Program 

Ford Motor Company Summary Report 

Provided to the U.S. Environmental Protection Agency 

BACKGROUND: 

Sulfur, which occurs naturally in crude oil, is known for its notorious ability to poison catalysts, affect 

heated oxygen sensors and dramatically reduce the functionality of advanced exhaust emissions 

systems. Laboratory research has shown sulfur to decrease catalyst criteria emissions conversion 

efficiency and impact the rich to lean Air/Fuel transition. Sulfur presence in gasoline is also known for its 

propensity to corrode metallic components found in the engine and fuels system as well as being linked

to fuel injector deposits. On the other hand, reductions in sulfur levels in gasoline result in immediate 

improvements in emission levels. Markets with highly advanced requirements for emissions control and 

durability are particularly concerned with maintaining market fuels at ultra-low sulfur levels of 10 ppm 

or less as exhaust catalysts must maintain extremely high efficiencies throughout the expected useful 

life of the vehicle, 150,000 miles in the proposed Tier 3 standards. As communicated previously and 

more recently during the April 2013 Tier 3 NPRM public hearings in addition to the Alliance of 

Automobile Manufacturers comments and via separate Ford comments submitted on July 1, 2013, Ford 

continues to strongly support a reduction of sulfur levels to a 10 ppm (or less) maximum for market 

fuels. This sulfur reduction is a key enabler to meet the strict standards imposed by the proposed Tier 3 

program/One National Program and is necessary to maintain the integrity of the engine and exhaust 

emission aftertreatment systems throughout the vehicle’s mandated full useful life (FUL). 

OBJECTIVE: 

A testing program was designed to assess the exhaust emission difference for a vehicle operating with 

10 ppm sulfur gasoline compared to the same vehicle operating with the same gasoline formulation 

containing 30 ppm sulfur. 

VEHICLE AND CATALYTIC EXHAUST AFTERTREATMENT SYSTEM: 

The vehicle selected was a Ford Explorer 2.0L GTDI calibrated to meet BIN50 or ULEV50 tailpipe 

emissions. The vehicle included an exhaust emission aftertreatment system that is representative of 

technologies under study to meet Tier 3 emissions standards (close-coupled, catalyst volume of 110 in3, 

150 g/ft3 loading of precious metal). A diagram of the exhaust system is shown in Figure 1. Additionally, 

the catalysts, UEGO & CMS were dynamometer aged to simulate 150,000 miles (using Ford’s proprietary 

ADP process for the proposed Tier 3 FUL requirement). 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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Figure 1: Catalyst configuration for 2.0L GTDI Explorer used in testing program. 

FUEL: 

The gasoline formulation used for this testing program (Appendix A) is aligned with the specifications

approved for LEV 3 (having 10 vol% ethanol, 8-11 ppm sulfur, 87-88.4 AKI). The LEV 3 certification fuel 

was chosen since the Tier 3 certification fuel is yet to be finalized. Given that the Tier 3 program is 

structured to harmonize with LEV 3, the Ford team agreed that the LEV 3 certification fuel would be the 

most suitable fuel. 

In order to minimize the variability in as many fuel parameters as possible and to eliminate any potential 

secondary effects on the emissions measurements, the higher sulfur gasoline blend was produced from 

the same batch of LEV III certification fuel by blending a sulfur additive into a portion of the LEV III fuel. 

The sulfur additive (Tert-butyl sulfide or Di-tert-butyl-disulfide) was selected to be the same additive 

used by EPA in their Tier 2 sulfur testing program and used in the SGS sulfur study that API included as 

part of their Tier 3 comments. 

TEST PROGRAM: 

The flow chart in Figure 2 depicts the testing program: 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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Figure 2: Testing program flow chart, typical certification procedures and 

practices were followed to conduct emission testing. 

Catalyst temperatures were recorded during a sampling of both city and highway driving on local area 

roads, see Figure 3. 

Figure 3: Sampling of local driving catalyst temperatures. 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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DATA ANALYSIS: 

The following summarizes the data collected for this sulfur study. 

Figure 4: NMHC+NOx FTP Tailpipe Emissions Summary for 2.0L GTDI Explorer. 

The data presented in Figure 4, shows that NMHC+NOx emissions increased by 16 mg/mile for the 26.5 

ppm sulfur fuel compared to the emissions measured when using the 10 ppm sulfur gasoline. Statistical

analyses using the T-test on the emissions data sets resulted in a P-value of 0.0216, which indicates that 

the difference between the two sulfur levels tested is statistically significant. Figure 5 shows the sec-byFigure 5: Cumulative FTP mass for NMHC+NOx Tailpipe Emissions for 2.0L GTDI Explorer. in sec-by-sec plot data used in sec-by-sec plot

• 2.0L GTDI Explorer 

• 150K FUL Catalyst (Dyno) 

• ETW = 4750 lbs 

• Calif. LEV III – E10/91RON 

• BIN50/ULEV50 

• Calibration 

• Aftertreatment
Ford Tier 3 Sulfur Test Program November 19, 2013 

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-sec cumulative measured mass for NMHC+NOx tailpipe emissions collected from the 2.0L GTDI Explorer 

across the FTP drive cycle. Shown are the lowest 10 ppm sulfur and highest 26.5 ppm sulfur NMHC+NOx 

emissions data, identified in Figure 4, to provide a perspective on the cumulative emissions range. 

The following shows the calculation for estimated total sulfur exposure experienced by the catalyst 

during the high-sulfur testing portion of this study. 

Although the total amount of sulfur exposure to the catalyst during this sulfur study appears to be 

relatively small, it is enough to contaminate the catalytic exhaust emission aftertreament system to 

result in an increase in tailpipe emissions for NMHC+NOx by 45 %. 

DISCUSSION: 

Recently, the American Petroleum Institute (API) sponsored a new study of sulfur reversibility conducted 

by SGS Environmental Testing Corp. (SGS Study) and subsequently submitted the results as part of joint

API and AFPM comments regarding the Tier 3 NPRM. This SGS study examined the sulfur reversibility in

a set of six late model vehicles in the under-6000 pound vehicle class. Five of the vehicles were certified 

to California SULEV II/PZEV, and one was certified to Federal Tier 2 Bin 5 standards. The SGS Study 

included new catalysts that were then aged using 18-43 ppm sulfur fuel for the equivalent of 120,000-

150,000 miles. After the aged catalysts were installed in each respective test vehicle, the study 

conducted catalyst purging for each vehicle using the EPEFE protocol, involving 10 wide open throttle 

(WOT) cycles, to establish baseline vehicle exhaust emissions. The vehicles were then operated and 

tested using the following order of 10, 80 and 10 ppm sulfur fuels. The base fuel used to test emissions 

after the catalyst purge contained 10 ppm sulfur while the high sulfur test gasoline contained 80 ppm 

sulfur. The study’s results indicated that the increase in exhaust emissions due to 80 ppm sulfur fuel 

was fully reversible after 70 miles of driving (operating with 10 ppm sulfur fuel) and preparation (purge) 

cycles linked to LA4 and US06 emission drive cycles. 

In summary, the following conclusions were drawn from the SGS study: 

• Gaseous exhaust emissions were higher for the vehicles conditioned and tested using 80 ppm 

sulfur fuel, relative to baseline tests run using 10 ppm sulfur fuel. 

• Mean emissions increased for vehicles run on the 80 ppm sulfur (relative to 10ppm sulfur) fuel 

as follows, with greater than 95% confidence: 

o Fleet average NMOG increased by 20% (0.002 g/mile change) 

o Fleet average NOx increased by 58% (0.006 g/mile change) 

o Fleet average CO increased by 31% (0.078 g/mile change) 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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Keep in mind that even if the sulfur effects were demonstrated to be reversible in the SGS Study, it is the 

average sulfur level on the catalyst that degrades efficiency and degrades criteria emission conversion 

performance, and, more importantly, that the act of purging (reversing the sulfur contamination) 

negatively impacts fuel economy. 

Figure 6 overlays the 2.0L Explorer data collected from the present test program with the data means 

collected from the SGS Study. 

Figure 6: API/SGS Sulfur Testing Program on 2009-2012 PZEV Vehicles 

 w/ 2.0L GTDI Explorer Comparison. 

When comparing the 2.0L GTDI Explorer data to the results from the SGS study, the following was 

observed: 

• 2.0L GTDI Explorer experienced an increase in NOx tailpipe emissions from a loss in 

catalyst efficiency (~0.5% less efficient). Most likely, the 2.0L GTDI Explorer NOx feedgas 

was greater than that of the API/SGS Study vehicles – this could be related to the engine 

displacement to vehicle mass ratio 

• 2.0L GTDI Explorer exhibited higher air mass flow (and encountered boosting during the 

second hill of the FTP) compared to the 2.0L Focus PZEV 

o 2.0L GTDI Explorer represents an engine displacement to vehicle mass ratio that 

aligns with what is expected to achieve CO2 compliance in the near future 

• 2.0L GTDI Explorer with 26.5ppm sulfur content in gasoline resulted in considerably 

higher emission degradation than the 80 ppm sulfur used in the SGS Study for a 

comparable engine 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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CONCLUSIONS: 

This sulfur study again confirms the deleterious effects of sulfur in our market fuel supply. Specifically, 

upon inspection of the emissions data from this Ford Tier 3 Sulfur Test Program, the following 

conclusions can be drawn: 

• The test vehicle exhaust emission aftertreatment system was exposed to approximately 1.1 

grams of sulfur during the mileage accumulation period (~ 15 gallons over 400 miles) 

• For a BIN50 certified vehicle under the proposed Tier 3 regulations, the sulfur contamination 

was: 

1. Sufficient to cause the NMHC+NOx to increase by 45% and 

2. Enough to result in a failed In-Use Verification Protocol (IUVP) test 

• A T-test was completed on the emissions data set (comparing 10 ppm sulfur and 26.5 ppm 

sulfur) with the conclusion that the two populations are significantly different 

(P = 0.0261) @ 95% confidence level 

• This study shows that ~30 ppm sulfur still contaminates today’s vehicles and is not compatible 

with future vehicles required to meet the low emissions regulations related to the proposed Tier 

3 rules 

Overall, these results corroborate the conclusions drawn from a May 2011 Technical Discussion and 

Presentation by Ford Motor Company entitled “Sulfur Effects on Gasoline Exhaust Emissions with 

Advanced Catalyst Formulations” where the following conclusions were previously stated: 

• According to market fuel surveys, leading countries have introduced 10 ppm maximum sulfur for 

gasoline 

• Sulfur in gasoline has been shown to poison catalysts resulting in reduced catalytic conversion 

efficiency 

• Sulfur is expected to continue to affect all precious metal catalyst formulations (Pd-only, Pd-Rh, 

Tri-metal, Pt-Rh) – i.e. No Catalyst Solution

• Laboratory and independent vehicle testing show >40% reduction in NOx emissions when 

decreasing sulfur from 30 ppm to 5 ppm 

Additionally, 

• Sulfur in gasoline can transition into sulfates which contribute to the fraction of PM 

• Very low levels of sulfur are needed to avoid sulfur poisoning of Lean NOx Traps 

In summary, the new data collected in this Ford Study, in tandem with the data provided by the SGS 

Study as well as previous work and literature, completely support the message that: 

Ford continues to strongly support a reduction of sulfur levels to a 10 ppm (or less) maximum 

for market fuels to meet the strict standards proposed by the Tier 3 program and finalized in the 

One National Program, in addition to maintaining the integrity of the engine and exhaust 

emission aftertreatment systems throughout the vehicle’s full useful life. 
Ford Tier 3 Sulfur Test Program November 19, 2013 

Docket No. EPA-HQ-OAR-2011-0135 

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APPENDIX A 
Ford Tier 3 Sulfur Test Program November 19, 2013 

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REFERENCES 

1. Alliance of Automobile Manufacturers, “Supplemental Comments of the Alliance of Automobile 

Manufacturers on Market Gasoline Sulfur,” EPA Docket EPA-HQ-OAR-2011-0135, October 31, 

2013. 

2. Ball, D.B., Clark, D., Moser, D., “Effects of Fuel Sulfur on FTP NOx Emissions from a PZEV 4 

Cylinder Application,” SAE 2011-01-01-0300, 2011. 

3. American Petroleum Institute and American Fuel & Petrochemical Manufacturers Attachment 

No. 11 to the EPA Docket EPA-HQ-OAR-2011-0135, SGS Environmental Testing Corp., 

“Reversibility of Gasoline Sulfur Effects on Exhaust Emissions From Late Model Vehicles,” June 

2013. 

4. U.S. EPA 2005 Review of the National Ambient Air Quality Standards for Particulate Matter: 

Policy Assessment of Scientific and Technical Information, US EPA OAQPS Staff Paper, EPA452/R-05-005a, December 2005. 

5. Truex, T.J., “Interaction of Sulfur with Automotive Catalysts and the Impact on Vehicle 

Emissions-A Review,” SAE 1999-01-1543. 

6. Farrauto, R.J., Mooney, J.J., “Effects of Sulfur on Performance of Aftertreatment Devices,” SAE 

920557, 1992. 

7. Hoyos, L.J., Praliaud, H., Primet, M., “Catalytic Combustion of Methane over Palladium 

Supported on Alumina and Silica in Presence of Hydrogen Sulfide,” App. Cat. A: General, 98, p. 

125, 1993. 

8. Beck, D.D., Krueger, M.H., Monroe, D.R., “The Impact of Sulfur on Three-Way Catalyst: Storage 

and Removal”, SAE Paper No. 910844, 1991. 

9. Benson, J., Burns, V., Gorse, R., Hochhauser, A., et. al., “Effects of Gasoline Sulfur Level on Mass 

Exhaust Emissions – Auto/Oil Air Quality Improvement Research Program,” SAE 912323, 1991. 

10. 78 FR 29816, May 21, 2013. 

11. U.S. EPA Summary and Analysis of the 2005 Highway and Nonroad Diesel Fuel Pre-Compliance 

Reports, EPA 420-R-06-12, June 2006. 

12. U.S. DOE. 2000. U.S. Petroleum Refining: Assuring the Adequacy and Affordability of Cleaner 

Fuels, June 2000. 

13. MathPro Inc. 2003. Evolution of Process Technology for FCC Naphtha Desulfurization: 1997-

2003; An Example of Technical Progress Induced by Environmental Regulation, March 2003. 

14. Draft EPA, “The Effects of Gasoline Sulfur Level on Emissions from Tier 2 Vehicles in the In-Use 

Fleet,” EPA-420-D-13-003, U.S. EPA, April 2013. 

15. Blumberg, K.O., Walsh, M.P., Pera, C., “Low-Sulfur Gasoline and Diesel: The Key to Lower Vehicle 

Emissions,” May 2003. 

16. Owen, K., Coley, T. “Automotive Fuels Reference Book,” 2nd Edition, 1995. 

17. Manufacturers of Emissions Controls Association (MECA), “The Impact of Gasoline Fuel Sulfur on 

Catalytic Emission Control Systems,” June 2013. 

18. Schleyer, C., Eng, K., Gorse, R., Gunst, R., et. al., “Reversibility of Sulfur Effects on Emissions of

California Low Emission Vehicles.” 

19. Ford Technical Discussion, Sulfur Effects on Gasoline Exhaust Emissions with Advanced Catalyst 

Formulations, May 2011. 

20. Worldwide Fuel Charter 5th Edition, September 2013, Source: www.autoalliance.org 

21. “Clean Air Facts: Cleaner Fuels for Cleaner Motor Vehicles,” Source: www.meca.org
Ford Tier 3 Sulfur Test Program November 19, 2013 

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REFERENCES cont. 

22. Review of Prior Studies of Fuel Effects on Vehicle Emissions,” CRC E-84, August 2008, Available 

at: www.crcao.org.

23. American Automobile Manufacturers Association/Association of International Automobile 

Manufacturers “AAMA/AIAM Study on the Effects of Fuel Sulfur on Low Emission Vehicle 

Criteria Pollutants,” December 1997. 

24. Schleyer, C., Gorse, r., Gunst, R., Barnes, G. et. al., “Effect of Fuel Sulfur on Emissions in 

California Low Emission Vehicles,” SAE 982726, 1998. 

25. D. M. DiCicco et. al. “The Effect of Fuel Sulfur on the HC, CO and NOx Conversion Efficiencies of 

Pd/Rh, Pt/Rh, Pd-Only and Tri-metal Catalysts,” 210th American Chemical Society National 

Meeting, August 1995. 

26. American Automobile Manufacturers Association/Association of International Automobile 

Manufacturers “AAMA/AIAM Study on the Effects of Fuel Sulfur on Low Emission Vehicle 

Criteria Pollutants,” December 1997. 

27. Coordinating Research Council (CRC), “CRC Sulfur/LEV Program,” December 1997. 

28. Takei, Y., Kinugasa, Y., Okada, M., Tanaka, T, Futimoto, Y., “Fuel Property Requirement for 

Advanced Technology Engines,” SAE 2000-01-2019. 

29. Anthony, J., Kubsh, J., “The Potential for Achieving Low Hydrocarbon and NOx Exhaust Emissions 

from Large Light-Duty Gasoline Vehicles,” SAE 2007-01-1261. 

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