Journal ArticleDOI
Interaction of NH3 with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study.
Filippo Giordanino,Elisa Borfecchia,Kirill A. Lomachenko,Andrea Lazzarini,Giovanni Agostini,Erik Gallo,Alexander V. Soldatov,Pablo Beato,Silvia Bordiga,Carlo Lamberti +9 more
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TLDR
Spectroscopic techniques are employed to get an insight into the geometry and electronic structure of Cu centers upon NH3 adsorption, revealing for the first time in Cu-SSZ-13 the presence of linear Cu(+) species in Ofw-Cu-NH3 or H3N- Cu- NH3 configuration.Abstract:
In the typical NH3–SCR temperature range (100–500 °C), ammonia is one of the main adsorbed species on acidic sites of Cu-SSZ-13 catalyst. Therefore, the study of adsorbed ammonia at high temperature is a key step for the understanding of its role in the NH3–SCR catalytic cycle. We employed different spectroscopic techniques to investigate the nature of the different complexes occurring upon NH3 interaction. In particular, FTIR spectroscopy revealed the formation of different NH3 species, that is, (i) NH3 bonded to copper centers, (ii) NH3 bonded to Bronsted sites, and (iii) NH4+·nNH3 associations. XANES and XES spectroscopy allowed us to get an insight into the geometry and electronic structure of Cu centers upon NH3 adsorption, revealing for the first time in Cu-SSZ-13 the presence of linear Cu+ species in Ofw–Cu–NH3 or H3N–Cu–NH3 configuration.read more
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Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials
Andrew M. Beale,Andrew M. Beale,Feng Gao,Ines Lezcano-Gonzalez,Ines Lezcano-Gonzalez,Charles H. F. Peden,János Szanyi +6 more
TL;DR: This review briefly discusses the structure and preparation of the CHA structure-based zeolite catalysts, and summarizes the key learnings of the rather extensive (but not complete) characterisation work, and provides some mechanistic details emerging from these investigations.
Journal ArticleDOI
Dynamic multinuclear sites formed by mobilized copper ions in NO x selective catalytic reduction.
Christopher Paolucci,Ishant Khurana,Atish A. Parekh,Sichi Li,Arthur J. Shih,Hui Li,John R. Di Iorio,Jonatan D. Albarracin-Caballero,Aleksey Yezerets,Jeffrey T. Miller,W. Nicholas Delgass,Fabio H. Ribeiro,William F. Schneider,Rajamani Gounder +13 more
TL;DR: It is demonstrated that under reaction conditions, mobilized Cu ions can travel through zeolite windows and form transient ion pairs that participate in an oxygen (O2)–mediated CuI→CuII redox step integral to SCR.
Journal ArticleDOI
Catalysis in a Cage: Condition-Dependent Speciation and Dynamics of Exchanged Cu Cations in SSZ-13 Zeolites
Christopher Paolucci,Atish A. Parekh,Ishant Khurana,John R. Di Iorio,Hui Li,Jonatan D. Albarracin Caballero,Arthur J. Shih,Trunojoyo Anggara,W. Nicholas Delgass,Jeffrey T. Miller,Fabio H. Ribeiro,Rajamani Gounder,William F. Schneider +12 more
TL;DR: Experimental and theory together reveal that the Cu sites respond sensitively to exposure conditions, and in particular that Cu species are solvated and mobilized by NH3 under SCR conditions.
Journal ArticleDOI
A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia
Ton V. W. Janssens,Hanne Falsig,Lars F. Lundegaard,Peter N. R. Vennestrøm,Søren Birk Rasmussen,Poul Georg Moses,Filippo Giordanino,Elisa Borfecchia,Kirill A. Lomachenko,Carlo Lamberti,Silvia Bordiga,Anita Godiksen,Susanne Mossin,Pablo Beato +13 more
TL;DR: In this article, the standard and fast selective catalytic reduction (SCR) of NO by NH3 are described in a complete catalytic cycle that is able to produce the correct stoichiometry while allowing adsorption and desorption of stable molecules only.
Journal ArticleDOI
Advances in theory and their application within the field of zeolite chemistry.
Veronique Van Speybroeck,Karen Hemelsoet,Lennart Joos,Michel Waroquier,Robert G. Bell,C. Richard A. Catlow +5 more
TL;DR: In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science and Directions for future model developments will be given.
References
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Journal ArticleDOI
Chemistry with ADF
G. te Velde,F.M. Bickelhaupt,Evert Jan Baerends,C. Fonseca Guerra,S. J. A. van Gisbergen,J.G. Snijders,T. Ziegler +6 more
TL;DR: The “Activation‐strain TS interaction” (ATS) model of chemical reactivity is reviewed as a conceptual framework for understanding how activation barriers of various types of reaction mechanisms arise and how they may be controlled, for example, in organic chemistry or homogeneous catalysis.
Journal ArticleDOI
Chemical and mechanistic aspects of the selective catalytic reduction of NOx by ammonia over oxide catalysts: A review
TL;DR: In this paper, the open literature concerning chemical and mechanistic aspects of the selective catalytic reduction of NO by ammonia (SCR process) on metal oxide catalysts is reviewed, and the results of spectroscopic studies of the adsorbed surface species, adsorption-desorption measurements, flow reactor and kinetic experiments are analyzed.
Journal ArticleDOI
Urea-SCR: a promising technique to reduce NOx emissions from automotive diesel engines
TL;DR: In this article, the authors discuss the fundamental problems and challenges if urea-SCR is extended to mobile applications, including the control strategy for urea dosing, the high freezing point of urea, and the long term stability of the catalyst.
Journal ArticleDOI
X-ray absorption edge determination of the oxidation state and coordination number of copper: application to the type 3 site in Rhus vernicifera laccase and its reaction with oxygen
Lung Shan Kau,Darlene J. Spira-Solomon,James E. Penner-Hahn,Keith O. Hodgson,Edward I. Solomon +4 more
TL;DR: In this paper, a normalized difference edge analysis is used to quantitatively determine the oxidation states of the copper sites in type 2 copper-depleted (T2D) and native forms of the multicopper oxidase, Rhus vernicifera laccase.
Journal ArticleDOI
The State of the Art in Selective Catalytic Reduction of NOx by Ammonia Using Metal‐Exchanged Zeolite Catalysts
TL;DR: An overview of the selective catalytic reduction of NOx by ammonia (NH3•SCR) over metal-exchanged zeolites is given in this paper, where a comparison of Fe•ZSM•5 catalysts prepared by different methods and research groups shows that the preparation method is not a decisive factor in determining catalytic activity.