Practical catalysts often operate under dynamic conditions of temperature variations and sudden changes of feed composition that call for understanding of operation and catalyst structure under analogous experimental conditions. For instance, the copper-exchanged small-pore SSZ-13 catalyst used currently in the selective catalytic reduction of harmful nitrogen oxides from the exhaust gas of diesel-fuelled vehicles operates under recurrent ammonia dosage. Here, we report the design of unsteady state experiments that mimic such a dynamic environment to obtain key mechanistic information on this reaction. Through the combination of time-resolved X-ray absorption spectroscopy and transient experimentation, we were able to capture an ammonia inhibition effect on the rate-limiting copper re-oxidation at low temperature. The practical relevance of this observation was demonstrated by optimization of the ammonia dosage on a catalyst washcoat on cordierite honeycomb, resulting in lower ammonia consumption and an increase in nitrogen oxide conversion at low temperature.
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Nova, I. & Tronconi, E. Urea-SCR Technology for deNOx After Treatment of Diesel Exhausts (Springer, New York, 2014).
Nunney, M. J. Light and Heavy Vehicle Technology 4th edn (Routledge, New York, 2007).
Lamberti, C. & van Bokhoven, J. A. X-Ray Absorption and X-Ray Emission Spectroscopy (John Wiley & Sons, Chichester, 2016).
Kopelent, R. et al. Catalytically active and spectator Ce3+ in ceria-supported metal catalysts. Angew. Chem. Int. Ed. Engl. 54, 8728–8731 (2015).
Singh, J. et al. Generating highly active partially oxidized platinum during oxidation of carbon monoxide over Pt/Al2O3: in situ, time-resolved, and high-energy-resolution X-ray absorption spectroscopy. Angew. Chem. Int. Ed. Engl. 47, 9260–9264 (2008).
Paolucci, C. et al. Dynamic multinuclear sites formed by mobilized copper ions in NOx selective catalytic reduction. Science 357, 898–903 (2017).
Newton, M. A., Belver-Coldeira, C., Martínez-Arias, A. & Fernández-García, M. Dynamic in situ observation of rapid size and shape change of supported Pd nanoparticles during CO/NO cycling. Nat. Mater. 6, 528–532 (2007).
Nagai, Y. et al. In situ redispersion of platinum autoexhaust catalysts: an on-line approach to increasing catalyst lifetimes? Angew. Chem. Int. Ed. Engl. 47, 9303–9306 (2008).
Beale, A. M., Gao, F., Lezcano-Gonzalez, I., Peden, C. H. F. & Szanyi, J. Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials. Chem. Soc. Rev. 44, 7371–7405 (2015).
Iwamoto, M. et al. Copper(II) ion-exchanged ZSM-5 zeolites as highly active catalysts for direct and continuous decomposition of nitrogen monoxide. J. Chem. Soc. Chem. Commun. 1272–1273 (1986).
Wang, J., Zhao, H., Haller, G. & Li, Y. Recent advances in the selective catalytic reduction of NOx with NH3 on Cu-chabazite catalysts. Appl. Catal. B 202, 346–354 (2017).
Kwak, J. H., Tonkyn, R. G., Kim, D. H., Szanyi, J. & Peden, C. H. F. Excellent activity and selectivity of Cu-SSZ-13 in the selective catalytic reduction of NOx with NH3. J. Catal. 275, 187–190 (2010).
Fickel, D. W., D’Addio, E., Lauterbach, J. A. & Lobo, R. F. The ammonia selective catalytic reduction activity of copper-exchanged small-pore zeolites. Appl. Catal. B 102, 441–448 (2011).
Paolucci, C., Di Iorio, J. R., Ribeiro, F. H., Gounder, R. & Schneider, W. F. Catalysis science of NOx selective catalytic reduction with ammonia over Cu-SSZ-13 and Cu-SAPO-34. Adv. Catal. 59, 1–107 (2016).
Paolucci, C. 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).
Gao, F., Mei, D., Wang, Y., Szanyi, J. & Peden, C. H. F. Selective catalytic reduction over Cu/SSZ-13: linking homo- and heterogeneous catalysis. J. Am. Chem. Soc. 139, 4935–4942 (2017).
Gunter, T. et al. Structural snapshots of the SCR reaction mechanism on Cu-SSZ-13. Chem. Comm. 51, 9227–9230 (2015).
Gao, F. et al. Structure–activity relationships in NH3-SCR over Cu-SSZ-13 as probed by reaction kinetics and EPR studies. J. Catal. 300, 20–29 (2013).
Lomachenko, K. A. et al. The Cu-CHA deNOx catalyst in action: temperature-dependent NH3-assisted selective catalytic reduction monitored by operando XAS and XES. J. Am. Chem. Soc. 138, 12025–12028 (2016).
Janssens, T. V. W. et al. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia. ACS Catal. 5, 2832–2845 (2015).
Tyrsted, C. et al. Nitrate–nitrite equilibrium in the reaction of NO with a Cu-CHA catalyst for NH3-SCR. Catal. Sci. Tech. 6, 8314–8324 (2016).
Doronkin, D. E. et al. Operando spatially- and time-resolved XAS study on zeolite catalysts for selective catalytic reduction of NOx by NH3. J. Phys. Chem. C 118, 10204–10212 (2014).
Borfecchia, E. et al. Revisiting the nature of Cu sites in the activated Cu-SSZ-13 catalyst for SCR reaction. Chem. Sci. 6, 548–563 (2015).
Marberger, A., Ferri, D., Elsener, M. & Kröcher, O. The significance of Lewis acid sites for the selective catalytic reduction of nitric oxide on vanadium-based catalysts. Angew. Chem. Int. Ed. Engl. 55, 11989–11994 (2016).
Gao, F. et al. Understanding ammonia selective catalytic reduction kinetics over Cu/SSZ-13 from motion of the Cu ions. J. Catal. 319, 1–14 (2014).
Zhang, T., Qiu, F., Chang, H., Li, X. & Li, J. Identification of active sites and reaction mechanism on low-temperature SCR activity over Cu-SSZ-13 catalysts prepared by different methods. Catal. Sci. Tech. 6, 6294–6304 (2016).
Nova, I., Ciardelli, C., Tronconi, E., Chatterjee, D. & Bandl-Konrad, B. NH3-SCR of NO over a V-based catalyst: low-T redox kinetics with NH3 inhibition. AIChE J. 52, 3222–3233 (2006).
Auvray, X. et al. Local ammonia storage and ammonia inhibition in a monolithic copper-beta zeolite SCR catalyst. Appl. Catal. B 126, 144–152 (2012).
Lezcano-Gonzalez, I. et al. Determination of the nature of the Cu coordination complexes formed in the presence of NO and NH3 within SSZ-13. J. Phys. Chem. C. 119, 24393–24403 (2015).
Paolucci, C. et al. Isolation of the copper redox steps in the standard selective catalytic reduction on Cu-SSZ-13. Angew. Chem. Int. Ed. Engl. 53, 11828–11833 (2014).
Metkar, P. S., Balakotaiah, V. & Harold, M. P. Experimental study of mass transfer limitations in Fe- and Cu-zeolite-based NH3-SCR monolithic catalysts. Chem. Engin. Sci. 66, 5192–5203 (2011).
Luo, J. et al. New insights into Cu/SSZ-13 SCR catalyst acidity. Part I: nature of acidic sites probed by NH3 titration. J. Catal. 348, 291–299 (2017).
Su, W., Li, Z., Peng, Y. & Li, J. Correlation of the changes in the framework and active Cu sites for typical Cu/CHA zeolites (SSZ-13 and SAPO-34) during hydrothermal aging. Phys. Chem. Chem. Phys. 17, 29142–29149 (2015).
Lonyi, F. & Valion, J. A TPD and IR study of the surface species formed from ammonia on zeolite H-ZSM-5, H-mordenite and H-beta. Thermochim. Acta 373, 53–57 (2001).
Delahay, G., Kieger, S., Tanchoux, N., Trens, P. & Coq, B. Kinetics of the selective catalytic reduction of NO by NH3 on a Cu-faujasite catalyst. Appl. Catal. B 52, 251–257 (2004).
Deka, U. et al. Confirmation of isolated Cu2+ ions in SSZ-13 zeolite as active sites in NH3-selective catalytic reduction. J. Phys. Chem. C 116, 4809–4818 (2012).
Kleemann, M., Elsener, M., Koebel, M. & Wokaun, A. Investigation of the ammonia adsorption on monolithic SCR catalysts by transient response analysis. Appl. Catal. B 27, 231–242 (2000).
Kröcher, O. et al. Investigation of the selective catalytic reduction of NO by NH3 on Fe-ZSM5 monolith catalysts. Appl. Catal. B 66, 208–216 (2006).
Zhao, Y., Hu, J., Hua, L., Shuai, S. & Wang, J. Ammonia storage and slip in a urea selective catalytic reduction catalyst under steady and transient conditions. Ind. Eng. Chem. Res. 50, 11863–11871 (2011).
Chiarello, G. L., Nachtegaal, M., Marchionni, V., Quaroni, L. & Ferri, D. Adding diffuse reflectance infrared Fourier transform spectroscopy capability to extended X-ray-absorption fine structure in a new cell to study solid catalysts in combination with a modulation approach. Rev. Sci. Instrum. 85, 074102 (2014).
Marchionni, V., Kambolis, A., Nachtegaal, M., Kröcher, O. & Ferri, D. High energy X-ray diffraction and IR spectroscopy of Pt/Al2O3 during CO oxidation in a novel catalytic reactor cell. Catal. Struct. React. 3, 71–78 (2017).
Müller, O., Nachtegaal, M., Just, J., Lützenkirchen-Hecht, D. & Frahm, R. Quick-EXAFS setup at the SuperXAS beamline for in situ X-ray absorption spectroscopy with 10 ms time resolution. J. Synchrotron Radiat. 23, 260–266 (2016).
Figueroa, S. J. A. & Prestipino, C. PrestoPronto: a code devoted to handling large data sets. J. Phys. Conf. Ser. 712, 012012 (2016).
Koebel, M., Elsener, M. & Madia, G. Recent Advances in the Development of Urea-SCR for Automotive Applications SAE Technical Paper 2001-01-3625 (SAE International, 2001); https://doi.org/10.4271/2001-01-3625
The authors acknowledge financial support from the Swiss National Science Foundation and Competence Center for Materials Science and Technology.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Marberger, A., Petrov, A.W., Steiger, P. et al. Time-resolved copper speciation during selective catalytic reduction of NO on Cu-SSZ-13. Nat Catal 1, 221–227 (2018). https://doi.org/10.1038/s41929-018-0032-6
Chemical gradients in automotive Cu-SSZ-13 catalysts for NOx removal revealed by operando X-ray spectrotomography
Nature Catalysis (2021)
Nature Communications (2021)
Nature Reviews Materials (2021)
Nature Reviews Materials (2021)
In situ X-ray absorption study of Cu species in Cu-CHA catalysts for NH3-SCR during temperature-programmed reduction in NO/NH3
Research on Chemical Intermediates (2021)