Date: October 12, 2012

To: Brenda Shine, EPA/OAQPS/SPPD

From: Jeff Coburn

Subject: Meeting Minutes for October 10, 2012, Meeting Between the U.S. EPA and Representatives from Johnson Matthey

Introduction

On October 10, 2012, representatives of the U.S. Environmental Protection Agency (EPA) and their contractor (RTI International) participated in a meeting with representatives from Johnson Matthey, a specialty chemical co mpany. Representatives were present from Tracerco and Intercat, both of which are in J ohnson Matthey’s Process Technologies Division. The names and affiliations of the participants are included in Attachment 1 . The major discussion points are provided below.

Tracerco

The representative from Tracerco provided a brief presentation about the types of services and studies that Tracerco performs; a copy of the presentation is included as Attachment 2 to this memorandum. Tracerco uses lo w level radioactive tracers to diagnose process operations. The technologies can be used to assess flow rates, diagnose distillation column issues, and identify leaks, blockage s and other issues without disrupting normal processing. For example, the technology can be used to identify sources of flare gas flow in flare header systems using pulse injection of radioact ive material and measuring the time it takes to travel across different points within the flare header system.

Intercat

Intercat specializes in ca talysts for the fluid catalytic cracking unit (FCCU). Representatives from Intercat presented their recent work to better understand hydrogen cyanide (HCN) formation and emissions from the FCCU as well as the relationship between HCN and nitrogen oxide (NO X ) emissions from the FCCU. A copy of the presentation is included as Attachment 3 to this memorandum. Key points di scussed during the presentation are
summarized below.

 Most NO X emissions from a complete combustion FCCU are fuel NO X . That is, they are formed from nitrogen deposite d in the coke. Complete a nd partial combustion FCCU are not operated at temperatures that would generate thermal NO X . Most (85-90 percent) of
NO X is NO, with 8-12 percent N 2 O and little NO 2

.2

 Platinum (Pt) combustion additives generally favor NO X formation; NO X emissions are generally about 3 times higher than an FCCU with no combustion promoter. Pt combustion promoters were originally used to reduce afterburning of carbon monoxide (CO) and the resulting high temperatures in the dilute and exhaust gas sections of the regenerator. In the dense secti on of the regenerator, the cataly st acts as a heat sink so CO combustion does not create the same high temp erature perturbations as are caused when
CO burns in the dilute and exhaust gas sections of the regenerator.

 Non-Pt combustion promoters generally use pa lladium (Pd) and favor the conversion of fuel nitrogen (in the coke) to nitrogen (N 2 ) rather than NO X . Non-Pt combustion promoters do increase NO X emissions relative to no co mbustion promoter, but by only about 30 percent (compared to a factor of 3 for Pt combustion promoters).

 Partial burn FCCU do not use combustion promoters; the lack of oxygen in the regenerator prevents afterburning until the CO boiler. “Deeper” partial burn is marked by higher levels of CO (and HCN) in the regene rator exhaust; the higher CO levels in the exhaust lead to highe r combustion temperatures in and higher NO X emissions from the
CO boiler. The increase in NO X emissions relative to complete combustion units is due primarily to the generation of thermal NO X generation; CO boilers operate at higher temperatures than the regene rator and these temperatures are high enough to generate
NO X from N 2 in the inlet air. At the elevated te mperatures in the CO boiler, all of the HCN in the regenerator exhaust is expected to be converted to NO X . As such, partial burn FCCU are not expected to be significant HCN emission sources.

 Intercat did a series of te mperature ramping experiments with coked FCCU catalyst. These experiments showed that:

o With no combustion promoters, HCN formati on appears to have two mechanisms of formation as seen by two distinct peaks, one at about 570 °C and one at about 715 °C.

o Pt combustion promoters do not appear to significantly reduce the low temperature formation of HCN, but they greatly reduce the higher temperature formation of HCN ( i.e. , no significant secondary peak at higher temperatures).

o Non-Pt combustion promoters appear to reduce both the low temperature formation of HCN (smaller peak between 550 to 650 °C ) and the higher temperature formation of HCN (no significant secondary peak at high er temperatures, similar to Pt catalyst combustion promoters).

 From these temperature ramping experiments, Intercat concluded that HCN emissions should be lower with combus tion promoters than without, and that non-Pt combustion promoters should yield lower HCN emissions th an Pt combustion promoters. Therefore, the use of non-Pt combustion promoters cannot be the primary cause for the “discovery” of high HCN emissions. All of the complete combustion FCCU recently tested used nonPt catalyst promoters; therefore, the wide range in measured HCN concentrations suggests that other factors, su ch as regenerator design and nitrogen content of the coke, may play an important role in HCN emissions.

 Although theoretical, th e Intercat representatives hypothesi zed that spent catalyst return design may play a critical role in HCN emissi ons. The catalyst is generally returned at 520 °C. If the catalyst is return ed in the dilute phase or ne ar the top of the dense phase3

(or perhaps too near the air in lets where the temperature is cooler), the initial catalyst combustion may occur at temperatures below 600 °C, where HCN formation is favored. The HCN formed may then exit the rege nerator without expe riencing the higher temperatures where HCN may be converted to NO X or N 2 (either because the vapors are generated in or near the dilu te phase or in large air bubbles that “burp” through the dense phase of the regenerator). Thus, the regenerator design modifications made to lower NO X emissions may have had the unintended c onsequence of increasing HCN emissions.Attachment 1 Participants in October 10, 2012, EPA/Johnson Matthey Meeting

Industry Representatives Guido Aru, Intercat Bart de Graaf, Intercat Paul Diddams, Intercat Dave Ferguson, Tracerco

U.S. EPA Representatives
Andrew Bouchard
Eric Goehl
Brenda Shine

RTI International (EPA contractor)
Jeff Coburn
Kristin SrokaAttachment 2

Presentation Slides

Tracerco - Delivering Diagnostic Services and Measurement Solutions WorldwideDelivering diagnostic services and measurement solutions worldwide



### www.tracerco.com Tel: 281 291 7769



## Presented by Dave FergusonJuly 2010 TruTec  Scanning Services 

## 28 Office Locations Strategically Placed Worldwide For Rapid Response

North American Headquarters PASADENA, TEXAS Corporate Headquarters BILLINGHAM, UNITED KINGDOMJuly 2010 TruTec  Scanning Services 

# TRACERCO Diagnostics  Safety

• Tracerco is Licensed by State and Federal Agencies and inspected once a year by appropriate agencies

• Tracerco is responsible for the Transport

, Use, and Disposal of any radioactive material we bring onto your site

• Plant does NOT inform EPA, State, or Federal Agencies about testing

• Similar to radiographers, Tracerco will barricade an area around the injection point, but only about 15 feet in radius

• There is no danger to plant personnel working around process equipment, as long as they stay out of the barricaded area

• Our radiation sources are about 1000 times smaller than radiography sources.July 2010 TruTec  Scanning Services 

# TRU-SCAN ® 

# Procedure



# I=I

o 

# e -   July 2010 TruTec  Scanning Services 

# Tru-Grid  Scan Procedure

Packed Bed



# I=I

o 

# e -   July 2010 TruTec  Scanning Services 

# TRACERCO Diagnostics  Flow Study - Flare Flow MeasurementJuly 2010 TruTec  Scanning Services 

# TRACERCO Diagnostics  Flow Study

CO

Boiler FCC

Regen

Air Flue Gas

Detectors Injection PointJuly 2010 TruTec  Scanning Services 

# TRACERCO Diagnostics  Flow Study

Unit 1 Unit 2 Unit 4

Unit 5 Unit 6

Unit 7 Unit 3 D-1 D-4 D-2

D-5 D-3 D-6

D-7 D-8

D-9 

### Identify Leak Origination

Flow Meter Injection

• Measure where flow rate increases

• Repeat steps in Unit sub-header • Pinpoint leaking PSV • Eliminate Units that do not contributeJuly 2010 TruTec  Scanning Services 

## TRACERCO Diagnostics  Flow Study – Relief Valve Leakage

• Once it is determined which unit(s) are contributing to the flare flow, each PSV, block or
relief valves can be individually tested to
determine which are leaking

• Tracer flow (or lack thereof)
is used to determine which pressure relief devices are leaking and by how muchJuly 2010 TruTec  Scanning Services 

## Flow Measurement

Residence Time Distribution Studies Leak Testing 

# TRACERCO Diagnostics TMJuly 2010 TruTec  Scanning Services



# Any Questions?Attachment 3

Presentation Slides

FCC Regenerator Nitrogen Chemistry

# FCC Regenerator Nitrogen Chemistry

Bart de Graaf

Guido Aru

Paul Diddams

# FCC Regenerator N Chemistry

• Where does NOx come from in Full Burn regenerators?

• What’s different about Partial burn regenerators ?



## • Afterburn and CO Promotor Effects

• NOx Control Additives

• Cyanide in the FCC

• Preliminary Conclusions

# Nitrogen Balance

– Full Burn FCC

N in Feed 40% Feed N in Coke 

### RX

REGENERATOR C + O 2 

### = CO 2 

### + xs O 2



### Regen Air N in Products
10% NH 3 /HCN
2% Gasoline
15% LCO
33% Bottoms 

### Typical Coke: H in Coke 5

- 8% S in Coke 0

- 2% N in Coke 0

- 2%

# NOx Formation

– Full Burn

N in Feed 40% Feed N in Coke 

### RX

REGENERATOR

Regen Air N in Products
10% NH 3 /HCN
2% Gasoline
15% LCO
33% Bottoms 

### NOx in Flue Gas



### N in Coke

NOx N 2 

### HCN / NH 3 

### NOx comes from FEED Nitrogen (not combustion air)

# NOx Formation

– Full Burn

NOx formation in Full Burn regenerators is generally increased by :  high flue gas excess oxygen levels 

###  poor coke / air mixing ( regen. design)  use of Pt based CO promotors  use of Sb passivator often increases NOx What factors affect NOx formation?

# N

- Balance in the FCC Regen

N in Coke converts primarily to N 2 

## or NOx depending strongly on the absence or type of CO Promotor used

Example: Full Burn FCC Regenerator Nitrogen Balance:

In the absence of Pt

- COP most of the N in coke is converted to N

2 

## rather 

## than NOx No

- COP Pt

- COP COP NP

N in Coke ( wt %) 1.16 1.17 1.17

Total N in FG ( ppmw ) 478 492 498

NOx ( ppmw ) 112 388 145

wt % N in Coke to NOx 24 79 29

Balance:
wt % N in Coke to N2 (plus very small amounts of NH3 and HCN) 76 21 71

# NOx Reduction

– CO

- Promotion

Why do we use CO promotors?

CO promotors are used to reduce afterburning in the dilute phase

CO + 1⁄2 O 2  CO 2 - reaction releases heat 

### There is insufficient catalyst in the dilute phase to absorb the heat

CO Promotors move this reaction into the dense phase where the heat of reaction is absorbed by the high heat capacity of the catalyst

Pt

- based CO promotors have been used for many years and are very effective at controlling afterburn

... ... BUT, they also lead to increased NOx emissions

Non

- Pt promotors do the same job with much lower NOx formation

# NOx Reduction

– COP

- NP

FCC REGENERATOR

N 2 

### N in Coke HCN / NH 3



## Non

- Pt Promotors decrease NOx by elimination of Pt

NOx formation is promoted by Pt NOx How do non

- Pt promotors decrease NOx ?

# NOx Reduction

– COP

- NP

CO promotors (Pt, non

- Pt )

– CO oxidation effect is short

- lived



## NOx formation on Pt COP deactivates very slowly in FCC

– only be eliminated by change

- out of inventory

Immediate Stable
NOx Formation Commercial FCCU Transition from Pt COP to COP NP NOx drops by 70%

Pt COP

COP

- NP additions begin CO oxidation activity deactivates rapidly NOx ppm

# NOx Reduction

– Full Burn Units

Non

- Pt promotors are generally very efficient in Full Burn regenerators

NOx levels can generally be decreased to 10

- 20 ppm in the flue gas

COP

- NP has a Pt

- equivalent level of 375 ppm for CO promotion

NOx reduction is generally favored by:  good spent catalyst / air mixing  lower flue gas excess O 2 

###  elimination of Pt and Sb usage

Continuous addition via a dedicated addition system ensures most flexible and economic usage of additive How far can NOx be lowered using Non

- Pt Additives?

# Partial Burn Regenerators

What is different about Partial Burn?



### RX

REGENERATOR

Regen Air CO BOILER

COB Air C + O 2 

### = CO 2


### C + 1⁄2O 2 

### = CO



### CO + 1⁄2O 2 

### = CO 2 

### CO 2 

### CO

Steam CO + 1⁄2O 2 

### = CO 2



### CO 2 

### xs O 2

# Partial Burn Regenerators

What is different about Partial Burn?



### RX

REGENERATOR

Regen Air CO BOILER

COB Air NOx (1)


### HCN (2)



### Steam

HCN + O 2 

###  NOx

NOx (1)


### NOx (2)


### NOx (3)



### N in Coke

HCN / NH 3



### NOx + N 2 

### also, thermal NOx (3) 

### from COB air

# NOx Formation

– Partial Burn

NOx formation in Partial Burn

- without COP

# NOx Formation

– Partial Burn

What is different about NOx Reduction Partial Burn?

At high %CO in flue gas the level of NOx exiting the regen. decreases 

### markedly, but this is more than made up by an increase in emissions of reduced N species such as HCN !

HCN from the regenerator readily forms NOx in the CO boiler

Further NOx is formed in the CO boiler via thermal oxidation of nitrogen (thermal NOx )

– especially with older COB designs that do not have advanced features to maintain low peak flame temperatures

For additives to be effective they must decrease levels of the reduced N species leaving the regenerator...

Where COP’s are used, substitution to non

- Pt promotors is helpful

# NOx Formation

– Partial Burn

What are the best conditions to minimize NOx ?

Xs. O 2 % CO% 

### In Full burn

– increasing excess O2 increases NOx

In Partial Burn

– increasing CO increases overall NOx

There is a “sweet

- spot” at minimum excess O2 or minimum CO

# NOx Formation

– 2

- Stage Regen

What is different about 2

- Stage Regenerators?



### RG 1: Partial Burn

RG1 Air RG2: Full Burn

RG2 Air N in Coke

 NOx (1) 

### + HCN NOx (1)


### HCN (2)


### to COB

Coked Catalyst Clean Catalyst Partially Regen Catalyst 

### NOx (2)



### to COB

Residual N in Coke

 NOx (2)

# NOx Formation

– 2

- Stage Regen

What is different about 2

- Stage Regenerators?

Two

- Stage Regenerators are essentially a combination of Partial and


### Full Burn (note: some 2

- Stage regenerators operate in Partial Burn in both stages)



### NOx Reduction additives work better in Full Burn, for additives to be effective in Partial Burn stages they must decrease levels of the reduced N species leaving the regenerator...

Where COP’s are used, substitution to non

- Pt promotors is helpful

# Cyanide in the FCC

How much of the “intermediate” Cyanide leaves the regenerator?

N Chemistry in the regenerator is complex:



### Most of the N in Coke initially burns to form Cyanide, a minor portion forms Ammonia

Cyanide is reactive and readily converts to NOx , NH 3 

### and N 2 

### NOx may also be converted to N 2 

### via reaction with CO or coke

A small amount of Cyanide survives (up to 150 ppm) and exits with the flue gas

N 2



### N in Coke HCN / NH 3 

### NOx N 2

# Cyanide in the FCC w/o Additive

HCN is formed at a low temperatures but is thermally unstable, above ca. 650 ° C it is converted to other N species

N 2 O is formed at similar temperatures to NO, however N 2 O is also thermally unstable, above ca. 650 ° C (this may be an intermediate for conversion of NO to N 2 )

NH 3 levels are very low, but some ammonia may be reacting with SOx forming ammonium sulphate thereby preventing it’s detection

– we are still evaluating this possibility TPO Procedure
2 g sample (spent catalyst w or w/o 1 wt% additive)
Heat up to 730 ° C in 2%O2/N2 (total 50cc/min) from room temperature at
15 ° C/min , and hold at 730 ° C for 30min

Gas species monitored by an MKS multi

- gas analyzer:

H 2 O CO CO 2 COS CS 2 H 2 S SO 2 SO 3 HCN HNCO HNO 2 N 2 O NH 3 HNO 3 NO NO 2 propane propylene ethane ethylene formaldehyde formic acid

# HCN and NOx w/ w/o Additives

NOx is higher in the presence of Pt

- COP or COP

- NP : Pt > Pd > none

HCN is lower when either Pt

- COP or COP

- NP is added : none > Pt > Pd

w/ COP

- NP
lowest HCN w / Pt

- COP highest NO N o Additive
lowest NO highest HCN 

### A low temperature NO peak is also present with both Pt

- COP and COP

- NP : conversion of some of the HCN to NO

# CO Promotors Decrease Cyanide

How much of the “intermediate” Cyanide leaves the regenerator?

C yanide is fully converted via reaction with O 2 

### at temp’s above ca. 650 degC

Use of Pt

- COP or non

- Pt CO Promotor (COP

- NP) facilitates conversion of 

### cyanide (lower temperature required for cyanide conv.)

COP

- NP is more effective
than Pt

- COP (

lower temp.)

Residual cyanide levels depend on several factors, importantly: local O 2 

### and CO concentrations (mixing) and areas of low temperature (e.g. spent catalyst return)

# New Additives...

Aim: decrease HCN and NOx

HCN COP

- NP = 46I > 105F



### NO COP

- NP > 105F > 46I

Cyanide and NOx levels are not 

### simply trading

- off...

...they are independently variable by controlling selectivity to N 2 COP NP

46I

105F

COP NP

46I

105F

# Promising Leads...

# Cyanide in the FCC

Conclusions regarding Cyanide

N in Coke forms Cyanide at low temperatures (e.g. spent cat return)



### Cyanide is thermally unstable and converted to NOx and N 2


### Pt

- COP and COP

- NP (Pd) increase Cyanide conversion (Pd > Pt)

Pt favours Cyanide conversion to NOx

Pd favours Cyanide conversion to N 2 

### Residual HCN emissions depends on factors limiting it’s conversion...

# Conclusion

• NOx chemistry is complex, involving many N

- species

– Pt favours pathways that form NOx

– Pd favours pathways that convert N

- species to N

2



### – Both Pt and Pd decrease HCN

• Aging in the FCC Regenerator affects CO Promotors differently:

– Rapid Loss of CO oxidation



### – Aging of Pt does not decrease NOx !

– Aging of Pd has little impact on NOx

• HCN is especially formed at fronts in the regenerator

– Higher Coke, Lower Temperatures

– spent cat. distributio n



### – Mixing effects are very important

• Replace Pt

- COP’s with COP

- NP to decrease NOx w/o HCN penalty

# Mechanistic

Considerations 

# Appendix

# Thousands of reactions involved...

Homogeneous Formation of NO and N 2 O from the Oxidation of HCN and NH 3 at 600

– 1000 ° C V . J. WARGADALAM, 2000 The radicals could be replaced by the adsorbed species in heterogeneous reactions...

# One proposed elementary pathway for HCN + O 2 

# on Pt /Al 2 

# O 3

Catalytic oxidation of HCN over a 0.5% Pt /Al 2 O 3 catalyst, Zhao et al. 2006

# Comparison of Pd / Pt for HCN 

# oxidation/hydrolysis

“Hydrolysis and oxidation of gaseous HCN over heterogeneous catalysts”

, Krocher and Elsener 2009 HCN HCN NH 3

NOx

N 2 O 2 , H 2 O O 2 , H 2 O, NO

Pt > Pd

Pt is a stronger oxidizing catalyst; hydrolysis is more favorable on Pd ; a significant portion of N 2 is from the reaction b/w NH 3 and NOx on Pd. Pt > Pd

# Pathway for NO + CO

1. CO + * ↔ CO* 2. NO + * ↔ NO*
3. NO* + *  N* + O* rate limiting step
4. N* + N*  N 2 + 2*
5a. N* + NO*  N 2 O + 2* 5b. N* + NO  N 2 O + * 5c. NO* + NO*  N 2 O + O* 6. CO + O*  CO 2 + *

The reduction of NO is enhanced when the catalyst surface is partially reduced

-- e.g. Cu(II) ions act as NO adsorption sites while Cu(I) ions act as recipients of the O atoms produced through the dissociation

Catalytic removal of NO, Parvulescu et al. 1998

## Unique adsorption of NO on Pd /Al 2 

## O 3

In situ Raman spectra during CO + NO on
Pd (pre

- reduced/Al 2 O 3 300 o C

200 o C

100 o C

50 o C Cooling down Characteristic of the formation of PdO ; the accumulation of chemisorbed O atoms could lead to a shift of rate limiting step

In situ IR spectra during CO + NO on Pd (pre

reduced)/Al 2 O 3

An overview of kinetic and spectroscopic investigations on three

- way catalysts: mechanistic aspects of the CO+NO and CO+N 2 O reactions, Granger et al. 2005

## Comparison of Pt / Pd for CO oxidation and NO reduction by CO (contd.)

An overview of kinetic and spectroscopic investigations on three

- way catalysts: mechanistic aspects of the CO+NO and CO+N 2 O reactions, Granger et al. 2005 λ : the equilibrium adsorption constant

CO + NO N 2

N 2 O

## Over anatase

- supported metal oxides 

# Selective catalytic oxidation of NH 3

imide (NH 2 ) as common intermediate in SCO and SCR;

(Amores, Escribano et al. 1997)