Moreno-González, M.; Millán-Cabrera, R.; Concepción Heydorn, P.; Blasco Lanzuela, T.; Boronat Zaragoza, M. (2019). Spectroscopic Evidence and Density Functional Theory (DFT) Analysis of Low-Temperature Oxidation of Cu+ to Cu2+NOx in Cu-CHA Catalysts: Implications for the SCR-NOx Reaction Mechanism. ACS Catalysis. 9(4):2725-2738. https://doi.org/10.1021/acscatal.8b04717
Por favor, use este identificador para citar o enlazar este ítem: http://hdl.handle.net/10251/150608
Título:
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Spectroscopic Evidence and Density Functional Theory (DFT) Analysis of Low-Temperature Oxidation of Cu+ to Cu2+NOx in Cu-CHA Catalysts: Implications for the SCR-NOx Reaction Mechanism
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Autor:
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Moreno-González, Marta
Millán-Cabrera, Reisel
Concepción Heydorn, Patricia
Blasco Lanzuela, Teresa
Boronat Zaragoza, Mercedes
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Entidad UPV:
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Universitat Politècnica de València. Instituto Universitario Mixto de Tecnología Química - Institut Universitari Mixt de Tecnologia Química
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Fecha difusión:
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Resumen:
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[EN] Despite the intense investigation on the NH3-SCR-NOx reaction mechanism catalyzed by small pore Cu-CHA zeolites, neither the rate-determining step of the process nor the exact nature of the active sites under reaction ...[+]
[EN] Despite the intense investigation on the NH3-SCR-NOx reaction mechanism catalyzed by small pore Cu-CHA zeolites, neither the rate-determining step of the process nor the exact nature of the active sites under reaction conditions are clearly established. In this work, in situ EPR and IR techniques combined with DFT calculations are applied to the study of the oxidation half-cycle of the NH3-SCR-NOx reaction on Cu-SSZ-13 and Cu-SAPO-34 catalysts. EPR and IR spectroscopies unambiguously show that Cu+ is oxidized to Cu2+ at room temperature in the presence of the reaction mixture (NO, O-2, and NH3) or NO and O-2, producing adsorbed NO2, nitrites, and nitrates. Several pathways are proposed from DFT calculations to oxidize Cu+ cations placed in the plane of the 6R ring units of SSZ-13 and SAPO-34 to Cu2+, either by NO2 alone or by a mixture of NO and O-2, with activation energy barriers lower than 70 kJ mol(-1). The results reported here demonstrate that a reaction mechanism invoking the formation of nitrate/nitrite intermediates on copper cations attached to the zeolite framework can be operational in the low-temperature region (T < 350 degrees C). Moreover, different intermediates, nitrites versus nitrates, are preferentially stabilized, depending on the catalyst composition, silicoaluminophosphate vs aluminosilicate.
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Palabras clave:
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Zeolite
,
Chabazite
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Mechanism
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NH3-SCR-NOx
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EPR
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IR
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DFT
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Derechos de uso:
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Reserva de todos los derechos
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Fuente:
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ACS Catalysis. (issn:
2155-5435
)
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DOI:
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10.1021/acscatal.8b04717
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Editorial:
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American Chemical Society
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Versión del editor:
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https://doi.org/10.1021/acscatal.8b04717
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Código del Proyecto:
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info:eu-repo/grantAgreement/EC/H2020/671093/EU/MATching zeolite SYNthesis with CATalytic activity/
info:eu-repo/grantAgreement/MINECO//MAT2015-71261-R/ES/DISEÑO RACIONAL DE MATERIALES ZEOLITICOS CON CENTROS METALICOS PARA SU APLICACION EN PROCESOS QUIMICOS SOSTENIBLES, MEDIOAMBIENTALES Y ENERGIAS RENOVABLES/
info:eu-repo/grantAgreement/MINECO//CTQ2015-68951-C3-1-R/ES/TRATAMIENTOS CATALITICOS AVANZADOS PARA LA VALORIZACION DE LA BIOMASA Y LA ELIMINACION DE RESIDUOS ASOCIADOS/
info:eu-repo/grantAgreement/MINECO//SEV-2012-0267/
info:eu-repo/grantAgreement/MINECO//SEV-2016-0683/
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Descripción:
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"This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acscatal.8b04717."
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Agradecimientos:
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This work was supported by the Spanish Government through "Severo Ochoa Program" (Nos. SEV 2012-0267; SEV-2016-0683), No. MAT2015-71261-R, and No. CTQ2015-68951-C3-1-R, and by the European Union through No. ERC-AdG-2014-671093 ...[+]
This work was supported by the Spanish Government through "Severo Ochoa Program" (Nos. SEV 2012-0267; SEV-2016-0683), No. MAT2015-71261-R, and No. CTQ2015-68951-C3-1-R, and by the European Union through No. ERC-AdG-2014-671093 (SynCatMatch). Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational resources and technical support. R.M. acknowledges "La Caixa-Severo Ochoa" International PhD Fellowships (call 2015).
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Tipo:
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Artículo
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