This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Analysis and Modeling of NOx Reduction Based on the Reactivity of Cu Active Sites and Brønsted Acid Sites in a Cu-Chabazite SCR Catalyst
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 9, 2019 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
The NOx-reducing activity of a Cu-chabazite selective catalytic reduction (SCR) catalyst was analyzed over a wide temperature range. The analysis was based on the ammonia SCR (NH3-SCR) mechanism and accounted for Cu redox chemistry and reactions at Brønsted acid sites. The reduction of NOx to N2 (De-NOx) at Cu sites was found to proceed via different paths at low and high temperatures. Consequently, the rate-limiting step of the SCR reaction at Cu sites varied with the temperature. The rate of NOx reduction at Cu sites below 200°C was determined by the rate of Cu oxidation. Conversely, the rate of NOx reduction above 300°C was determined by the rate of NH3 adsorption on Cu sites. Moreover, the redox state of the active Cu sites differed at low and high temperatures. To clarify the role of the chabazite Brønsted acid sites, experiments were also performed using a H-chabazite catalyst that lacks Cu sites. NOx reduction via the NO2-NH3 reaction was found to occur at Brønsted acid sites at high temperatures (up to 600°C). We also analyzed the chabazite catalyst’s activity towards NH3 oxidation, which significantly affects NOx reduction at high temperatures. Cu sites were required for NH3 oxidation; NH3 was not oxidized in their absence. However, the formation of the by-product NO increased as the content of Brønsted acid sites in the Cu-chabazite catalyst decreased. It was therefore suggested that Brønsted acid sites contribute to the reduction of NO formed during NH3 oxidation. Numerical studies were conducted to develop an SCR reaction model that incorporates these processes. The resulting model accurately predicted the outcomes of NOx reduction experiments under diverse conditions including some involving transient temperature changes.
CitationTsukamoto, Y., Fukuma, T., and Kusaka, J., "Analysis and Modeling of NOx Reduction Based on the Reactivity of Cu Active Sites and Brønsted Acid Sites in a Cu-Chabazite SCR Catalyst," SAE Technical Paper 2019-24-0150, 2019, https://doi.org/10.4271/2019-24-0150.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
|[Unnamed Dataset 2]|
|[Unnamed Dataset 3]|
|[Unnamed Dataset 4]|
|[Unnamed Dataset 5]|
|[Unnamed Dataset 6]|
|[Unnamed Dataset 7]|
|[Unnamed Dataset 8]|
- Paolucci, C., Verma, A.A., Bates, S.A., Kispersky, V.F. et al. , “Isolation of the Copper Redox Steps in the Standard Selective Catalytic Reduction on Cu-SSZ-13,” Angew. Chem. Int. Ed. 53:11828-11833, 2014, doi:10.1002/anie.201407030.
- Janssens, T.V.W., Falsig, H., Lundegaard, L.F., Vennestrøm, P.N.R. et al. , “A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia,” ACS Catal. 5:2832-−2845, 2015, doi:10.1021/cs501673g.
- Tsukamoto, Y., Utaki, S., Fukuma, T., and Kusaka, J. , “Reactivity Analysis and Modeling of Cu-SCR Based on NH3-SCR Mechanism Considering Cu Redox,” JSAE 6:1211-1216, 2018, doi:10.11351/jsaeronbun.49.1211.
- Lezcano-Gonzalez, I., Deka, U., Arstad, B., Van Yperen-De Deyne, A. et al. , “Determining the Storage, Availability and Reactivity of NH3 within Cu-Chabazite-based Ammonia Selective Catalytic Reduction Systems,” Phys. Chem. Chem. Phys. 16:1639-1650, 2014, doi:10.1039/c3cp54132k.
- Zhu, H., Kwak, J.H., Peden, C.H.F., and Szanyi, J. , “In Situ DRIFTS-MS Studies on the Oxidation of Adsorbed NH3 by NOx over a Cu-SSZ-13 Zeolite,” Catalysis Today 205:16-23, 2013, doi:10.1016/j.cattod.2012.08.043.
- Ohya, N., Hiyama, K., Tanaka, K., Konno, M. et al. , “Kinetic Modeling Study of NOx Conversion Based on Physicochemical Characteristics of Hydrothermally Aged SCR/DPF Catalyst,” SAE Int. J. Fuels Lubr. 10(3), 2017, doi:10.4271/2017-01-2386.
- Gao, F., Walter, E.D., Karp, E.M., Luo, J. et al. , “Structure-Activity Relationships in NH3-SCR Over Cu-SSZ-13 as Probed by Reaction Kinetics and EPR Studies,” Journal of Catalysis 300:20-29, 2013, doi:10.1016/j.jcat.2012.12.020.
- Olsson, L., Sjövall, H., and Blint, R.J. , “A Kinetic Model for Ammonia Selective Catalytic Reduction Over Cu-ZSM-5,” Applied Catalysis B: Environmental 81(3-4):203-217, 2008, doi:10.1016/j.apcatb.2007.12.011.
- Sjövall, H., Blint, R.J., and Olsson, L. , “Detailed Kinetic Modeling of NH3 and H2O Adsorption, and NH3 Oxidation over Cu-ZSM-5,” J. Phys. Chem. C 113(4):1393-1405, 2009, doi:10.1021/jp802449s.
- Colombo, M., Nova, I., and Tronconi, E. , “Detailed Kinetic Modeling of the NH3-NO/NO2 SCR Reactions Over a Commercial Cu-zeolite Catalyst for Diesel Exhausts After Treatment,” Catalysis Today 197:243-255, 2012, doi:10.1016/j.cattod.2012.09.002.
- Su, C., Brault, J., Munnannur, A., Liu, Z. et al. , “Model-Based Approaches in Developing an Advanced Aftertreatment System: An Overview,” SAE Technical Paper 2019-01-0026 , 2019, doi:10.4271/2019-01-0026.
- Colombo, M., Koltsakis, G., Nova, I., and Tronconi, E. , “Modelling the Ammonia Adsorption-Desorption Process over an Fe-Zeolite Catalyst for SCR Automotive Applications,” Catalysis Today 188(1):42-52, July 1, 2012, doi:10.1016/j.cattod.2011.09.002.
- Olsson, L., Wijayanti, K., Leistner, K., Kumar, A. et al. , “A Multi-Site Kinetic Model for NH3-SCR Over Cu/SSZ-13,” Applied Catalysis B: Environmental 174-175:212-224, 2015, doi:10.1016/j.apcatb.2015.02.037.
- Bendrich, M., Scheuer, A., Hayes, R.E., and Votsmeier, M. , “Unified Mechanistic Model for Standard SCR, Fast SCR, and NO2 SCR Over a Copper Chabazite Catalyst,” Applied Catalysis B: Environmental 222:76-87, March 2018, doi:10.1016/j.apcatb.2017.09.069 axisuite documentation version 2017A.
- Paolucci, C., Parekh, A.A., Khurana, I., Di Iorio, J.R. et al. , “Catalysis in a Cage: Condition-Dependent Speciation and Dynamics of Exchanged Cu Cations in SSZ-13 Zeolites,” J. Am. Chem. Soc. 138:6028-6048, 2016, doi:10.1021/jacs.6b02651.
- Gao, F., Mei, D., Wang, Y., Szanyi, J., and Peden, C.H.F. , “Selective Catalytic Reduction over Cu/SSZ-13: Linking Homo- and Heterogeneous Catalysis,” J. Am. Chem. Soc. 139:4935-4942, 2017, doi:10.1021/jacs.7b01128.
- Jabłon´ska, M. and Palkovits, R. , “Copper Based Catalysts for the Selective Ammonia Oxidation into Nitrogen and Water Vapour - Recent Trends and Open Challenges,” Applied Catalysis B: Environmental 181:332-351, 2016, doi:10.1016/j.apcatb.2015.07.017.
- Magdalena, J.A.B.Ł.O.Ń.S.K.A., Lucjan, C.H.M.I.E.L.A.R.Z., and Agnieszka, W.Ę.G.R.Z.Y.N. , “Selective Catalytic Oxidation (SCO) of Ammonia into Nitrogen and Water Vapour over Hydrotalcite Originated Mixed Metal Oxides - a Short Review,” CHEMIK 2013, 67(8):701-710, doi:10.1007/s10562-011-0653-8.
- Hinokuma, S., Matsuki, S., Kawabata, Y., Shimanoe, H. et al. , “Copper Oxides Supported on Aluminum Oxide Borates for Catalytic Ammonia Combustion,” J. Phys. Chem. C 120:24734-24742, 2016, doi:10.1021/acs.jpcc.6b07157.
- Smith, M.A., Depcik, C.D., Klinkert, S., Hoard, J.W., Bohac, S.V., and Assanis, D.N. , “NO2 Reaction Pathways With NH3 on an Fe-Zeolite SCR Catalyst,” in ASME 2011 Internal Combustion Engine Division Fall Technical Conference, 633-641, doi:10.1115/ICEF2011-60114.
- Gao, F., Walter, E.D., Kollar, M., Wang, Y. et al. , “Understanding Ammonia Selective Catalytic Reduction Kinetics over Cu/SSZ-13 from Motion of the Cu Ions,” Journal of Catalysis 319:1-14, 2014, doi:10.1016/j.jcat.2014.08.010.
- Gao, F., Washton, N.M., Wang, Y., Kollár, M. et al. , “Effects of Si/Al Ratio on Cu/SSZ-13 NH3-SCR Catalysts: Implications for the Active Cu Species and the Roles of Brønsted Acidity,” Journal of Catalysis 331:25-38, 2015, doi:10.1016/j.jcat.2015.08.004.
- Li, H., Paolucci, C., Khurana, I., Wilcox, L.N. et al. , “Consequences of Exchange-Site Heterogeneity and Dynamics on the UV-Visible Spectrum of Cu-Exchanged SSZ-13,” Chem. Sci. 10:2373, 2019, doi:10.1039/c8sc05056b.
- Auvray, X., Partridge, W., Choi, J.-S., Pihl, J. et al. , “Kinetic Modeling of NH3-SCR over a Supported Cu Zeolite Catalystusing Axial Species Distribution Measurements,” Applied Catalysis B: Environmental 163:393-403, 2015, doi:10.1016/j.apcatb.2014.08.003.
- Vollmer, J.M., Stefanovich, E.V., and Truong, T.N. , “Molecular Modeling of Interactions in Zeolites: An Ab Initio Embedded Cluster Study of NH3 Adsorption in Chabazite,” J. Phys. Chem. B 103:9415-9422, 1999, doi:10.1021/jp990571h.