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Development of a Downsized Urea SCR Catalyst with High DeNOx Performance over a Wide Range of Exhaust Gas Temperatures
Technical Paper
2014-01-1543
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Recently, there has been increasing interest in catalysts with smaller volume for a Urea Selective Catalytic Reduction (SCR) system especially for use in heavy duty vehicles. In this study, several new concepts were developed in order to improve the deNOx performance of the SCR catalysts over a wide range of operating temperatures and this resulted in a compact SCR system.
First, the urea decomposition process in diesel exhaust gas was elucidated. Several kinds of urea decomposition catalysts were investigated and the material which showed the best performance in NH3 (ammonia) formation was used to improve the low temperature performance of Cu-zeolite catalysts.
Second, the method of reducing the amount of NH3 slip was investigated. It is well known that the amount of ammonia slip after the Urea-SCR system must be under 10 ppm and therefore materials with lower NH3 slip are preferred. The smaller the amount of NH3 slip, the larger the amount of urea that can be injected into the system and this leads to higher NOx conversion.
A material that could store NH3 at temperatures even higher than 450 degrees C was added to Cu-zeolite in order to enhance the adsorption of NH3 at high temperatures and this consequently reduced the amount of NH3 slip.
The concepts described above were combined and this resulted in the development of a high deNOx performance Cu-zeolite catalyst that also made it possible to reduce the volume of the SCR catalyst as well.
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Citation
Tran, M., Yamashita, Y., and Aono, N., "Development of a Downsized Urea SCR Catalyst with High DeNOx Performance over a Wide Range of Exhaust Gas Temperatures," SAE Technical Paper 2014-01-1543, 2014, https://doi.org/10.4271/2014-01-1543.Also In
References
- Kwak , J.H. , Tonkyn , R.G. , Kim , D.H. , Szanyi , J. et al. Excellent activity and selectivity of Cu-SSZ-13 in the Selective Catalytic reduction of NOx with NH 3 J. of Catalysis 275 2 187 190 2010 10.1016/j.jcat.2010.07.031
- Frickel , D.W. , D'Addio , E. , Lauterbacha , J.A. , Lobo , R.F. The Ammonia Selective Catalytic Reduction Activity of Copper Exchanged Small Pore-zeolites App. Catal. B: Environmental 102 441 448 2011
- Steven , J. S. , Se , H. Oh. , Chang , H. K. , David , B. B. et al. Thermal Durability of Cu-CHA NH 3 -SCR Catalysts for Diesel NOx Reduction Catalysis Today 184 252 261 2012 10.1016/j.cattod.2011.10.034
- Koebel , M. and Strutz , E. O. Thermal and Hydrolytic Decompositon of Urea for Automotive Selective Catalytic Reduction System: Thermochemical and Practical Aspects Ind. Eng. Chem. Res. 42 2093 2100 2003
- Yim , S. D. , Kim , S. J. , Baik , J. H. , Nam , I. S. et al. Decomposition of U rea into NH 3 for the SCR Process Ind. Eng. Chem. Res. 43 4856 4863 2004
- Girard , J. , Snow , R. , Cavataio , G. , and Lambert , C. The Influence of Ammonia to NOX Ratio on SCR Performance SAE Technical Paper 2007-01-1581 2007 10.4271/2007-01-1581
- Girard , J. , Cavataio , G. , Snow , R. , and Lambert , C. Combined Fe-Cu SCR Systems with Optimized Ammonia to NOx Ratio for Diesel NOx Control SAE Int. J. Fuels Lubr. 1 1 603 610 2008 10.4271/2008-01-1185
- Hünnekes , E. , van der Heijden , P. , and Patchett , J. Ammonia Oxidation Catalysts for Mobile SCR Systems SAE Technical Paper 2006-01-0640 2006 10.4271/2006-01-0640
- Alano , E. , Jean , E. , Perrot , Y. , Brunel , J. et al. Compact SCR for Passenger Cars SAE Technical Paper 2011-01-1318 2011 10.4271/2011-01-1318
- Tan , J. , Solbrig , C. , and Schmieg , S. The Development of Advanced 2-Way SCR/DPF Systems to Meet Future Heavy-Duty Diesel Emissions SAE Technical Paper 2011-01-1140 2011 10.4271/2011-01-1140
- Kleemann , M. , Elsener , M. , Koebel , M. , and Wokaun , A. Hydrolysis of Isocyanic Acid on SCR Catalysts Ind. Eng. Chem. Res. 39 4220 4126 2000
- Lundstrom , A. , Snelling , T. , Morsing , P. , Gabrielsson , P. et al. Urea Decomposition and HNCO hydrolysis over Titanium Dioxide, Fe-Beta and γ -Alumina Applied Catalysis B: Environmental 106 273 279 2011 10.1016/j.apcatb.2011.05.010
- Koebel , M. and Elsener , M. Ammonia Production by Combined Pyrolysis/Hydrolysis of Urea PSI Annu. Rep. Annex 5 50 1992
- Murata , Y. , Tokui , S. , Watanabe , S. , Daisho , Y. et al. Improvement of NOx Reduction Rate of Urea-SCR System by NH 3 Adsorption Quantity Control SAE Technical Paper 2008-01-2498 2008 10.4271/2008-01-2498