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Robust SCR Design Against Environmental Impacts
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 05, 2016 by SAE International in United States
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Significant reduction in Nitrogen Oxide (NOx) emissions will be required to meet LEV III Emissions Standards for Light Duty Diesel passenger vehicles (LDD). As such, Original Equipment Manufacturers (OEMs) are exploring all possible aftertreatment options to find the best balance between performance, robustness and cost. The primary technology adopted by OEMs in North America to achieve low NOx levels is Selective Catalytic Reduction (SCR) catalyst. The critical parameters needed for SCR to work properly are: an appropriate reductant such as ammonia (NH3) typically provided as urea, adequate operating temperatures, and optimum Nitrogen Dioxide (NO2) to NOx ratios (NO2/NOx). The NO2/NOx ratio is mostly influenced by Precious Group Metals (PGM) containing catalysts located upstream of the SCR catalyst. Different versions of zeolite based SCR technologies are available on the market today and these vary in their active metal type (iron, copper, vanadium), and/or zeolite type. To select an appropriate SCR type, the application’s operating conditions as well as environmental factors must be considered. To fundamentally understand these differences, a study was conducted where various SCR catalysts are evaluated in a laboratory environment in regards to, 1) PGM contamination 2) operating temperature and resulting thermal aging, 3) NO2 levels from the system architecture, 4) the extent of reductant usage and overexposure, and 5) the impact of oxygen concentrations during the aging of catalysts. In this study, various types of copper SCR catalysts are evaluated using several unique and standard testing methods to expose them to conditions simulating lifetime exposure. Some non-ideal or “worst case scenarios” were explored regarding Diesel Emissions Fluid (DEF) usage, dosing quality and thermal exposure. Results highlight the advantages and disadvantages of various SCR and zeolite types available in the marketplace.
CitationJacques, J., Pauly, T., Zammit, M., Ahari, H. et al., "Robust SCR Design Against Environmental Impacts," SAE Technical Paper 2016-01-0954, 2016, https://doi.org/10.4271/2016-01-0954.
- Cha J., Kwon, J., Cho, Y., and Park S., “The effect of exhaust gas recirculation (EGR) on combustion stability, engine performance and exhaust emissions in a gasoline engine”, KSME international Journal, 2001, 15 (10), p. 1442-1450.
- Abd-All G.H., “Using exhaust gas recirculation in internal combustion engines: a review”, Energy Conversion and Management, 2002, 43 (8), p. 1027-1042.
- Machrafi, H., Cavadias, S., and Guibert P., “An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects”, Combustion and Flame, 2008, 155, p. 476-489.
- Brickhold, F., Meingast, U., Wasserman, P., and Deutshmann O., “Modeling and simulation of the injection of urea-water-solution for automotive SCR DeNOx-systems”, Applied Catalysis B: Environmental, 70, (2007), p. 119-127.
- Fang, H. and DaCosta H., “Urea thermolysis and NOx reduction with and without SCR catalysts”, Applied Catalysis: B Environmental, 46 (2003), p. 17-34.
- Chimner, C., "Transient On-Road Emission Reduction of an LNT + SCR Aftertreatment System," SAE Int. J. Commer. Veh. 1(1):315-326, 2009, doi:10.4271/2008-01-2641.
- Dykes, E., "NOx Performance of an LNT+SCR System Designed to Meet EPA 2010 Emissions: Results of Engine Dynamometer Emission Tests," SAE Int. J. Commer. Veh. 1(1):327-337, 2009, doi:10.4271/2008-01-2642.
- Xu, L., McCabe, R., Ruona, W., and Cavataio, G., "Impact of a Cu-zeolite SCR Catalyst on the Performance of a Diesel LNT+SCR System," SAE Technical Paper 2009-01-0285, 2009, doi:10.4271/2009-01-0285.
- Kamasamudram, K., Henry, C., Currier, N., and Yezerets, A., "N2O Formation and Mitigation in Diesel Aftertreatment Systems," SAE Int. J. Engines 5(2):688-698, 2012, doi:10.4271/2012-01-1085.
- Lambert C., “Future Directions in Diesel SCR Systems” 2012 CLEERs Workshop http://cleers.org/workshops/workshop2012/presentations/Lambert_CLEERS2012.pdf.
- Smith, M., Depcik, C., Hoard, J., Bohac, S. et al., "The Effects of CO, H2, and C3H6 on the SCR Reactions of an Fe Zeolite SCR Catalyst," SAE Technical Paper 2013-01-1062, 2013, doi:10.4271/2013-01-1062.
- Cavataio, G., Jen, H., Girard, J., Dobson, D. et al., "Impact and Prevention of Ultra-Low Contamination of Platinum Group Metals on SCR Catalysts Due to DOC Design," SAE Int. J. Fuels Lubr. 2(1):204-216, 2009, doi:10.4271/2009-01-0627.
- Jen, H., Girard, J., Cavataio, G., and Jagner, M., "Detection, Origin and Effect of Ultra-Low Platinum Contamination on Diesel-SCR Catalysts," SAE Int. J. Fuels Lubr. 1(1):1553-1559, 2009, doi:10.4271/2008-01-2488.
- Chen, X., Currier, N., Yezerets, A., and Kamasamudram, K., "Mitigation of Platinum Poisoning of Cu-Zeolite SCR Catalysts," SAE Int. J. Engines 6(2):856-861, 2013, doi:10.4271/2013-01-1065.
- Nova, I., Ciardelli, C., Tronconi, E., Chatterjee, D. and Brandl-Konrad, B., NH3-NO/NO2 Chemistry over V-based catalysts and its role in the mechanism of the Fast SCR reaction. Catalysis Today, 2006. 114: p. 3-12.
- Sjovall, H., Olsson, L., Fridell, E., and Blint, R.J., Selective catalytic reduction of NOx with NH3 over Cu-ZSM-5 - The effect of changing the gas composition. Applied Catalysis: B Environmental, 2006, 64, p. 180-188.
- Smith, M., Depcik, C., Klinkert, S., Hoard, J., Bohac, S., and Assanis D., “NO2 Reaction Pathways with NH3 on an Fe-Zeolite SCR catalyst” ASME Paper ICEF 2011-60114.
- Ruggeri, M., Nova, I., Tronconi, E., “Experimental study of the NO oxidation to NO2 over metal promoted zeolites aimed at the identification of the standard SCR rate determining step”, Topics in Catalysis, 56, (2013), p. 109-113.
- Sjovall, H., Blint, R., Olsson, L., “Detailed kinetic modeling of NH3 SCR over Cu-ZSM-5”, Applied Catalysis B: Environmental, 92, (2009), p. 138-153.
- Schmieg, S., Oh, S., Kim, C., Brown, D., Lee, J., Peden, C., and Kim D. “Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction”, Catalysis Today, 184, (2012), 1, p. 252-261.
- Kumar, A., An, H., Smith, M. Kamasamudram, K., Currier, N. and Yezerets A., “Effect of Hydrothermal Aging on Various Catalytic Functions of a Small-Pore Cu-Zeolite Catalyst with CHA-type Structure”, NAM 2013, Louisville, KY.
- Smith, M., Kamasamudram, K., Szailer, T., Kumar, A. et al., "Impact of Sulfur-Oxides on the Ammonia Slip Catalyst Performance," SAE Technical Paper 2014-01-1545, 2014, doi:10.4271/2014-01-1545.
- Cheng, Y., Lambert, C., Kim, D., Kwak, J., Cho, S., and Peden C. “The different impact of SO2 and SO3 on Cu/zeolite SCR catalysts” Catalysis Today, 151 (2010), p. 266-270.
- Cheng, Y., Montreuil, C., Cavataio, G., and Lambert, C., "The Effects of SO2 and SO3 Poisoning on Cu/Zeolite SCR Catalysts," SAE Technical Paper 2009-01-0898, 2009, doi:10.4271/2009-01-0898.
- Kumar, A., Smith, M., Kamasamudram, K., Currier, N., An, H., and Yezerets A. “Impact of different forms of feed sulfur on small-pore Cu-zeolite SCR catalyst”, Catalysis Today, 231, (2014), p.75-82.
- Klinkert, S., Hoard, J., Sathasivam, S., Assanis, D., and Bohac S., “Design of a Flow Reactor for Testing Multi-Brick Catalyst Systems Using Rapid Exhaust Gas Composition Switches”, ASME Paper, ICEF2009-14016.
- Kamasamudram, K., Currier, N., Chen, X., and Yezerets A., “Overview of the practically important behaviors of zeolite-based urea-SCR catalysts, using compact experimental protocol”, Catalysis Today, 151, (2010), 3-4, p. 212-222.
- DG Enterprise, 2012. “Reference documents -adoption of Global Technical Regulations (GTRs)”, European Commission, DG Enterprise and Industry, internet, updated 23/07/2012, http://ec.europa.eu/enterprise/sectors/automotive/documents/unece/gtr/
- UNECE, 2007. “Global technical regulation No. 4”, ECE/TRANS/180/Add.4, 25 January 2007, http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a4e.pdf
- Kwak, J., Lee, J., Burton, S., Lipton, A., Peden C., and Szanyi J., “A common intermediate for N2 formation in enzymes and zeolites: side-on Cu-Nitrolsyl complexes”, Angewandte Chemie, 125, (2013), 38, p. 10169-10173.
- Ma, L., Cheng, Y., Cavataio, G., McCabe, R., Fu, L., and Li J. “Characterization of commercial Cu-SSZ-13 and Cu-SAPO-34 catalysts with hydrothermal treatment for NH3-SCR of NOx in diesel exhaust”, Chemical Engineering Journal, 225, (2013), 323-330.
- Cheng, Y., Hoard, J., Lamber, C., Kwak J., and Peden C. “NMR studies of Cu/zeolite SCR catalys hydrothermally aged with urea” Catalysis Today 136 (2008) 1-2, p. 34-39.