Journal Article10.1021/JACS.6B02651
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
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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.
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Abstract: The relationships among the macroscopic compositional parameters of a Cu-exchanged SSZ-13 zeolite catalyst, the types and numbers of Cu active sites, and activity for the selective catalytic reduction (SCR) of NOx with NH3 are established through experimental interrogation and computational analysis of materials across the catalyst composition space. Density functional theory, stochastic models, and experimental characterizations demonstrate that within the synthesis protocols applied here and across Si:Al ratios, the volumetric density of six-membered-rings (6MR) containing two Al (2Al sites) is consistent with a random Al siting in the SSZ-13 lattice subject to Lowenstein’s rule. Further, exchanged CuII ions first populate these 2Al sites before populating remaining unpaired, or 1Al, sites as CuIIOH. These sites are distinguished and enumerated ex situ through vibrational and X-ray absorption spectroscopies (XAS) and chemical titrations. In situ and operando XAS follow Cu oxidation state and coordinatio...
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Citations
Single-Atom Catalysts across the Periodic Table.
TL;DR: A compositional encyclopedia of SACs is provided, celebrating the 10th anniversary of the introduction of this term, and examines the coordination structures and associated properties accessed through distinct single-atom-host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis.
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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.
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Small-Pore Zeolites: Synthesis and Catalysis
Michiel Dusselier,Mark E. Davis +1 more
TL;DR: This review first focuses on the relevant synthesis details of all 8MR zeolites and provides some generalized findings and related insights, and catalytic applications where 8MRZeolites either have been commercialized or have dominated investigations are presented, with the aim of providing structure-activity relationships.
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Selective Catalytic Reduction over Cu/SSZ-13: Linking Homo- and Heterogeneous Catalysis.
TL;DR: Detailed reaction kinetics are reported on low-temperature standard NH3-SCR, supplemented by DFT calculations, as strong evidence that the low-Temperature oxidation half-cycle occurs with the participation of two isolated CuI ions via formation of a transient [CuI(NH3)2]+-O2-[CuI (NH3]2]+ intermediate.
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References
Structure and properties of metal-exchanged zeolites studied using gradient-corrected and hybrid functionals. II. Electronic structure and photoluminescence spectra
Florian Göltl,Jürgen Hafner +1 more
TL;DR: The influence of the choice of the exchange-correlation functional (semilocal gradient corrected or hybrid functionals) on the electronic properties of metal-exchanged zeolites has been investigated, leading to better agreement with experiment and many-body perturbation theory for close-packed SiO(2) polymorphs where detailed experimental information is available.
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Molecular Origins of Selectivity in the Reduction of NOx by NH3
TL;DR: In this article, density functional theory calculations are used to elucidate the origins of the remarkable selectivity in thermal deNOx, where NH2 radical reacts with NO at rates typical of gas phase radical reactions to produce a relatively strongly bound H2NNO adduct that readily rearranges and decomposes to N2 and H2O.
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Water-Catalyzed Activation of H2O2 by Methyltrioxorhenium: A Combined Computational–Experimental Study
TL;DR: Experiments confirm the predicted catalytic role of water: the kinetics of both steps are strongly dependent on the water concentration, and water appears directly in the rate law.
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A diamine copper(I) complex stabilized in situ within the ferrierite framework. Catalytic properties
TL;DR: In this article, the structure of the copper(I) complex [Cu(NH 3 ) 2 ] + has been determined by single-crystal X-ray diffraction and the obtained formula is [Cu 0.34 O 72 ) 0.68 ] 0.21 A.
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CHAPTER 2:First-principles Thermodynamic Models in Heterogeneous Catalysis
J. M. Bray,W. F. Schneider +1 more
- 02 Dec 2013
TL;DR: In this article, the authors describe and demonstrate computational approaches to modeling surface adsorption, a process fundamental to all heterogeneous catalysts that takes into account surface structure, adsorbate-adsorbate interactions, and reaction conditions.
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