Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst
Published January 15, 2019 by SAE International in United States
Downloadable datasets for this paper availableAnnotation of this paper is available
Ammonia-selective catalytic reduction (SCR) systems have been introduced commercially in diesel vehicles, however catalyst systems with higher conversion efficiency and better control characteristics are required to know the actual emissions during operation and the emissions in random test cycles. Computational fluid dynamics (CFD) is an effective approach when applied to SCR catalyst development, and many models have been proposed, but these models need experimental verification and are limited in the situations they apply to. Further, taking account of redox cycle is important to have better accuracy in transient operation, however there are few models considering the cycle. Model development considering the redox reactions in a zeolite catalyst, Cu-ZSM-5, is the object of the research here, and the effects of exhaust gas composition on the SCR reaction and NH3 oxidation at high temperatures are investigated. The simulations are compared with the experimental results of a surrogate gas, a mixture of nitrogen monoxide (NO), oxygen (O2), water vapor (H2O), and nitrogen (N2), and the accuracy of the developed model is validated. To investigate the effects of O2 concentration on standard SCR and NH3 oxidation, the experiments are conducted with the surrogate gas. The results suggest that the O2 has a larger reaction order (1.25-1.51) to NH3 oxidation than that to the standard SCR (0.73-0.75). The model considering these reaction orders of O2 predicts the effect of O2 on NOx and NH3 conversions well. A transient operation experiment is also conducted with the Cu-ZSM-5 catalyst. The experiment consists of NH3 adsorption part and NO reduction part, where the re-oxidizing of copper does not occur. The results clearly show that Cu+ does not contribute to the SCR reaction. Further, the NH3-SCR simulation model was greatly improved by considering the redox reaction cycle and the concentrations of oxygen.
CitationEijima, W., Shibata, G., Kobashi, Y., Koiwai, R. et al., "Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst," SAE Technical Paper 2019-01-0024, 2019, https://doi.org/10.4271/2019-01-0024.
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- Tronconi, E. et al. , “Modelling of an SCR Catalytic Converter for Diesel Exhaust After Treatment: Dynamic Effects at Low Temperature,” Catalysis Today 105:529-536, 2005.
- Nova, I. et al. , “NH3-SCR of NO over a V-Vased Catalyst: Low-T Redox Kinetics with NH3 Inhibition,” AIChE Journal 52(9):3222-3233, 2006, doi:10.1002/aic.10939.
- Olsson, L. et al. , “A Kinetic Model for Ammonia Selective Catalytic Reduction over Cu-ZSM-5,” Applied Catalysis B: Environmental 81:203-217, 2008.
- Sjövall, H. et al. , “Detailed Kinetic Modeling of NH3 and H2O Adsorption, and NH3 Oxidation over Cu-ZSM-5,” The Journal of Physical Chemistry C 113:1393-1405, 2009, doi:10.1021/jp802449s.
- Sjövall, H. et al. , “Detailed Kinetic Modeling of NOx Adsorption and NO Oxidation over Cu-ZSM-5,” Applied Catalysis B: Environmental 87:200-210, 2009.
- Skarlis, S.A. et al. , “Modeling NH3 Storage over Fe- and Cu-Zeolite Based, Urea-SCR Catalysts for Mobile Diesel Engines,” Procedia - Social and Behavioral Sciences 48:1672-1682, 2012, doi:10.1016/2012.06.1142.
- Joshi, S.Y. et al. , “New Insights into the Mechanism of NH3-SCR over Cu- and Fe-Zeolite Catalyst: Apparent Negative Activation Energy at High Temperature and Catalyst Unit Design Consequences,” Applied Catalysis B: Environmental 226:565-574, 2018.
- Metlar, P.S. et al. , “Selective Catalytic Reduction of NO with NH3 on Iron Zeolite Monolithic Catalysts: Steady-State and Transient Kinetics,” Applied Catalysis B: Environmental 104:110-126, 2011.
- Zhang, H., Xi, Y., Su, C., and Liu, Z. , “Lab Study of Urea Deposit Formation and Chemical Transformation Process of Diesel Aftertreatment System,” SAE Technical Paper 2017-01-0915, 2017, doi:10.4271/2017-01-0915.
- Liu, Y., Su, C., Clerc, J., Harinath, A. et al. , “Experimental and Modeling Study of Ash Impact on DPF Backpressure and Regeneration Behaviors,” SAE Int. J. Engines 8(3):1313-1321, 2015, doi:10.4271/2015-01-1063.
- Yasuyuki, T. et al. , “Effect of Oxygen Concentration in NH3-SCR Reaction over Fe- and Cu-Loaded Beta Zeolites,” Journal of the Japan Petroleum Institute 55(1):57-66, 2012.
- Ye, Q. et al. , “Activity, Propene Poisoning Resistance and Hydrothermal Stability of Copper Exchanged Chabazite-Like Zeolite Catalysts for SCR of NO with Ammonia in Comparison to Cu/ZSM-5,” Applied Catalysis A: General 427-428:24-34, 2012.
- Zheng, Y. et al. , “Effects of CO, H2 and C3H6 on Cu-SSZ-13 Catalyzed NH3-SCR,” Catalysis Today 264:44-54, 2016.
- Sultana, A. et al. , “Selective Catalytic Reduction of NOx with NH3 over Different Copper Exchanged Zeolites in the Presence of Decane,” Catalysis Today 164:495-499, 2011.
- Bendrich, M. et al. , “Unified Mechanistic Model for Standard SCR, Fast SCR, and NO2 SCR over a Copper Chabazite Catalyst,” Applied Catalysis B: Environmental 222:76-87, 2018.
- Paolucci, C. et al. , “Isolation of the Copper Redox Steps in the Standard Selective Catalytic Reduction on Cu-SSZ-13,” Angewandte Chemie International Edition 53:11828-11833, 2014, doi:10.1002/anie.201407030.
- Janssens, T.V.W. et al. , “A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia,” ACS Catalysis 5:2832-2845, 2015, doi:10.1021/cs501673g.
- Eijima, W. et al. , “Development of Ammonia-SCR Reaction Computation Model and Experimental Studies of Zeolite Catalysts,” in the 9th International Conference on Modeling and Diagnostics for Advanced Engine Systems, Symposium Proceedings, 2017, A311.
- Supriyanto et al. , “Global Kinetic Modeling of Hydrothermal Aging of NH3-SCR over Cu-Zeolite,” Applied Catalysis B: Environmental 163:382-392, 2015.
- Meyer, J. et al. , “In-Cylinder Oxygen Concentration Estimation for Diesel Engines Via Transport Delay Modeling,” in American Control Conference, 2011, 396-401.
- Shwan, S. et al. , “Kinetic Modeling of H-BEA and Fe-BEA as NH3-SCR Catalysts - Effect of Hydrothermal Treatment,” Catalysis Today 197:24-37, 2012.
- Priya, S.V. et al. , “A Collective Case Screening of the Zeolites made in Japan for High Performance NH3-SCR of NOx,” Bulletin of the Chemical Society of Japan 91:355-361, 2018.