# Date: December 10, 2012

To: Brenda Shine, EPA/OAQPS/SPPD

From: Jeff Coburn

Subject: Meeting Minutes for December 4, 2012, Meeting Between the U.S. EPA and

Representatives from BASF

On December 4, 2012, representatives of the U.S. Environmental Protection Agency

(EPA) and their contractor (RTI International) participated in a meeting with representatives

from BASF to discuss fluid catal ytic cracking unit (FCCU ) catalyst additives and their impact on

the formation/degradation of hydrogen cyanide (HCN).

Attendees

BASF Representatives

C.P. Kelkar

Jason Smith

U.S. EPA Representatives

Andrew Bouchard

Eric Goehl

Brenda Shine

Ravi Srivastava

RTI International (EPA contractor)

Jeff Coburn

Kristin Sroka

Discussion Topics

BASF representatives provided a brief bac kground on the company. BASF is a large

diversified chemical company and the largest gl obal catalyst supplier, including a variety of

automotive and industrial catalysts. BASF’s catal yst division is headquartered in Newark, New

Jersey. Considering the U.S. refining industr y, BASF is the second largest refining catalyst

supplier behind Grace Davidson; Albemarle a nd Intercat are the other key refining

catalyst/catalyst additive suppliers in the U.S.

# 2 BASF has several FCCU catalyst additives to help refineries meet emission requirements.

EnviroSOx is a newly reformulated sulfur oxides (SOx) emission reduction catalyst additive that

contains a lower content of rare earth materials than previous formulations. COnquer is a new,

zero rare earth, palladium-based combustion prom oter to lower carbon monoxide (CO) emissions

as well as lower nitrogen oxi de (NOx) emissions. CLEANOx® is a proven NOx emission

reduction additive. EPA representatives noted that it appeared that the palladium-based

combustion promoters significantly reduced NOx emissions compared to platinum-based

combustion promoters, but available data did no t seem to indicate that straight NOx catalyst

additives were that effective in further reduc ing NOx emissions. BASF representatives did note

that the effectiveness of CLEANOx® is depe ndent on site-specific parameters, but that

reductions on the order of 20-30 percent were achievable.

BASF representatives then provided a summ ary of the tests they have conducted on

FCCU catalyst additive impacts on nitrogen compounds, particularly HCN. BASF designed a

“lambda sweep” lab scale testing apparatus that us es a fixed bed of FCCU catalyst and varies the

gas phase concentration in orde r to assess the reaction chemistr y as FCCU catalyst goes from

reductive atmosphere to an oxidative atmosphe re (see Attachment 1). A typical experiment

starts with high CO levels in the sw eep gas (reductive atmosphere; lambda ( λ ) less than 1) then

gradually increases the oxygen in the sweep ga s until there is excess oxygen in the catalyst

reaction chamber (oxidative atmosphere; λ greater than 1). At st oichiometric amounts of

oxygen, λ equals 1. The lambda sweep can be perfor med with various concentrations of water

(steam), HCN, ammonia (NH 3 

# ), or nitric oxide (NO) in the sweep gas. All experiments were

conducted at 704 degrees Celsius (°C) (1,300 degr ees Fahrenheit (°F)), a typical complete

combustion FCCU regenerator operating temperatur e. Four different catalyst additives were

tested for each sweep gas scenario:

1) platinum on alumina oxide (Pt/Al 2 

# O 3 

# ), a traditional platinum-based combustion

promoter;

2) palladium on alumina oxide (Pd/Al 2 

# O 3 

# );

3) palladium and metal oxide mixt ure on alumina oxide (Pd/MOx/Al 2 

# O 3 

# ); and

4) palladium, copper oxide, and metal oxide mixture on alumina oxide

(Pd/CuO/MOx/Al 2 

# O 3 

# ).

A series of experiments was performed w ith different nitrogen species (HCN, NH 3 

# and

NO) fed to the reactor and the concentration of these nitrogen species were measured leaving the

reactor. Any nitrogen loss thr ough the reactor was assumed to be converted to nitrogen because

elemental nitrogen is not detected by the analy zer (which uses Fourier transform infrared

spectroscopy (FTIR)). In genera l, steam in the sweep gas reduces the activity of the catalyst.

HCN is expected to be produced as a result of nitrogen in the c oke. When HCN was fed into the

system as the primary nitrogen species, the metal oxide and copper/metal oxide catalyst

formulations showed lower HCN outlet concentra tions than the platinum or palladium (only)

catalysts, suggesting that the metal oxides or copper/metal oxide formulations were more

effective in catalyzing the conve rsion of HCN to othe r nitrogen species, wh ich are then more

easily converted to elemental nitrogen. As su ch, the newer combustion promoters (which use

# 3 metal oxides or copper/metal oxides in addi tion to palladium) should help to lower HCN

concentrations compared to trad itional platinum-based combustion promoters. The EPA asked if

they had done similar studies at different temp eratures. BASF responded that they had not done

similar experiments at lower temperature, bu t they acknowledged that there were often

temperature variations within the FCCU.

The experiments with catalyst in the reaction chamber were e xpected to model the “dense

phase” of the FCCU regenerator. BASF also ra n similar experiments with no catalyst in the

reaction chamber to simulate the dilute phase of the FCCU regenerator. In these experiments,

they attempted to simulate coke burn-off. At high CO/CO 2 

# levels, a majority of the HCN in the

sweep gas remained in the off gas. At lower CO/CO 2 

# ratios (presumably higher oxygen feed),

the HCN concentrations leaving the reaction (or combustion) ch amber were lower than when

there were high CO/CO 2 

# ratios, but they were still much hi gher than when there was catalyst in

the reaction chamber. According to BASF representatives, this s uggests that any HCN that exits

the dense phase and enters the d ilute phase in the regenerator ha s a very good chance of being

emitted as HCN.

The EPA representatives thanked the BASF repr esentatives for coming to talk and share

the results of their testing. The EPA representatives request ed a copy of the presentation

material. BASF representatives said they would review the presentation to make sure there was

no proprietary information and would send the EPA a copy of the presentation once it is cleared

by BASF.

# Attachment 1

Understanding the chemistry of NO

x 

# reduction in the FCC regenerator

by lambda sweep test

Qi Fu, David M. StockwellUnderstanding the chemistry of NOxreduction in the FCC regeneratorby lambda sweep testQi Fu*, David M. Stockwell25 Middlesex Essex-Turnpike, Iselin, NJ 08830 (USA)*qi.fu@basf.comIntroductionNOxemissions from the fluid catalytic cracking units(FCCU) are being limited byregulatory agencies to an increasing degree. NOxis formed in the FCCU regenerator, wherecoke is burned off to provide process heat and rejuvenate the catalyst. Typical levels of NOxinthe flue gas from fluid catalytic cracking regeneration units vary between 50 and 150 ppm,depending upon feed nitrogen content and regenerator conditions. Use of low NOxCOoxidation promoter is a simple, cost-effective wayin existing FCC units to promote cokecombustion and reduce CO and NOxemission, without significant modifications in theregenerator design or the unit operating conditions.In order to develop better low NOxCO promoter, it is essential to understand thechemistry of NOxformation in the FCC regenerator. Pathways for conversion of nitrogencontaining species proposed earlier [1-2] include formation of N2via NO+CO, NO+coke,NO+reduced ceria OSC, and NH3-SCR, once NOxis formed, as well as oxidation of HCN andNH3. However, during coke-burn experiments, a rather complex reaction network is involvedwhich does not lend itself towards dissection of these individual pathways. In this paper, westudy the discrete NOxreaction pathways by the lambda sweep test method[3] to learn whichare most relevant under realistic FCCU conditions for different types of CO oxidationpromoters.Materials and MethodsFour CO oxidation promoters, Pt/Al2O3, Pd/Al2O3, Pd/CeOx/Al2O3andPd/CuO/CeOx/Al2O3were prepared by wet impregnation of appropriate salt solutions on Al2O3microspheres (95 m2•g-1, 0.50 ml g-1 water pore volume), followed by calcination 2 h at 650°C. The loading of precious metal is 500 ppm. We have learned FCC catalyst has activity forHCN hydrolysis and can improve the selectivity of NH3oxidation to N2. To avoid theinterference of FCC catalyst and overheating of theCO promoters, an inert kaolin microspherewas used both as a control and as a diluent, and this material had been steamed at 816°C for 4hours in 100% steam. CO promoters were tested fresh by blending with this previouslysteamed material. The performance testing was doneusing the proprietary lambda sweep testmethod [3]. Down stream gas analysis was done by FTIR with N2yield determined by materialbalance. The dose of CO promoter was adjusted to match CO conversion activity, which isreported as an overall lean CO2/CO by using the yields of CO2and CO obtained when the feedwasλ>1.Results and DiscussionIt has been found that HCN is the primary nitrogen-containing product formed fromFCC coke combustion [3-4]. To understand how HCN and NH3are converted to NOx/N2, wefed HCN, NH3, and NOxindividually as well as the various combinations with or withoutsteam to probe the pathways of the oxidation of HCN, the hydrolysis of HCN to NH3, theselective oxidation of NH3, and the reduction of NO to N2by NH3, coke or CO and the effectof the catalysts. The concentration of co-fed gasesCO2, CO, SOx, H2O and O2varied cyclicallyand exponentially, but the total flow rate of thesemixtures was held constant to maintainfluidization and mass transfer constant. We have found that HCN oxidation is faster than itshydrolysis to NH3so not all HCN is hydrolyzed to NH3, but can be directly oxidized to NOx. Inthe lean region, NO cannot be reduced by either COor coke but it can be reduced by NH3;Addition of CuO reduces NOxyield by improving selectivity of HCN oxidation toN2. Additionof CeO2lowers NOxyield by improving selectivity of NH3oxidation to N2and enhancing NOxreduction by NH3.0%20%40%60%80%100%0.1 1 10 100Lambda of feed = 2*[O2]/[CO]

NOx yield, %Pt/Al2O3Pd/Al2O3Pd/CeOx/Al2O3Pd/CuO//CeOx/Al2O3RichLean0%20%40%60%80%100%0.1 1 10 100lambda of Feed = 2*[O2]/[CO]

NOx yield, %Pt/Al2O3Pd/Al2O3Pd/CeOx/Al2O3Pd/CuO/CeOx/Al2O3Rich Lean0%20%40%60%80%100%0.1 1 10 100lambda of feed = 2*[O2]/[CO]

NOx yield, %Pt/Al2O3Pd/Al2O3Pd/CeOx/Al2O3Pd/CuO/CeOx/Al2O3Rich Lean0%20%40%60%80%100%0.1 1 10 100lambda of Feed = 2*[O2]/[CO]

NOx yield, %Pt/Al2O3Pd/Al2O3Pd/CeOx/Al2O3Pd/CuO/CeOx/Al2O3Rich LeanNOxN2NH4+Brφnsted siteNOxN2NH4+Brφnsted site+NH3N2NO+CON2NOXHCNNOx/N2HCNBasic site+ H2ONH3HCNNOx/N2HCNBasic site+ H2ONH3Figure 1NOxselectivity with various N-species in the feed a)HCN only; b)NH3only; c) NOonly; d)NH3and NO.SignificanceThe often-proposed NO-CO and NO-coke pathways are seldom travelled by FCC NOx.Instead, NOxis reduced by reacting with NH3via SCR route. The preferred route is tohydrolyze HCN to NH3and/or selectively oxidize NH3to N2.References1.Zhao, X., Peters, A. W., and Weatherbee, G. W.,Ind. Eng. Chem. Res.1997, 36, 45352.Stevenson, S., Socha, R., and Mathias, M.,Ind. Eng. Chem. Res.2005, 44, 29663.Stockwell, D. M.,Stud. Surf. Sci. Catal. (Fluid Catalytic Cracking VII) (M.L. Occelli,Ed.),2007, 166, 79; US Pat. Appl. 2007/01668264.Houser, T. J., Hull, M., Alway, R. M. and Biftu, T., Int.J. Chem. Kinet.,1980, 12, 569