Multivariate curve resolution analysis applied to time-resolved synchrotron X-ray Absorption Spectroscopy monitoring of the activation of copper alumina catalyst
Contribuinte(s) |
Universidade Estadual Paulista (UNESP) |
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Data(s) |
03/12/2014
03/12/2014
15/06/2014
|
Resumo |
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Processo FAPESP: 07/53073-4 Processo FAPESP: 13/50023-7 Processo FAPESP: 13/05346-2 The pure X-ray Absorption (XAS) spectral constituents and related concentration profiles characterizing the reduction of a copper-based catalyst supported on hierarchically porous alumina were disentangled from a set of time-resolved Quick-XAS using a Multivariate Curve Resolution-methodology. First, the number of components involved in the data set and the range of existence of intermediate species were determined by Principal Component Analysis (PCA). Then, a Multivariate Curve Resolution with Alternating Least Squares fitting of the set of time-resolved Quick-XANES was performed using the constraints of non-negativity of both absorption and concentration and of closure of concentration. Consideration about the strategy of use of the chemometric methods and robustness regarding the reliability of results for time-resolved XAS data is discussed. The intermediate copper species determined by MCR-ALS is at the monovalent oxidation state and characterized by a local order of 2 oxygen atoms at 1.915 angstrom. Upon isothermal treatment under 60% H-2/He at 250 degrees C for 30 min, the intermediate species appears quite resistant to complete copper reduction. Copper speciation obtained using MCR-ALS method leads to very different results than those obtained using bulk CuO, Cu2O and metallic Cu as constituents, MCR-ALS concentration profile so-determined being fully consistent with the reducibility of the catalyst measured by TPR. (C) 2013 Elsevier B.V. All rights reserved. |
Formato |
114-122 |
Identificador |
http://dx.doi.org/10.1016/j.cattod.2013.10.077 Catalysis Today. Amsterdam: Elsevier Science Bv, v. 229, p. 114-122, 2014. 0920-5861 http://hdl.handle.net/11449/111409 10.1016/j.cattod.2013.10.077 WOS:000333450100014 |
Idioma(s) |
eng |
Publicador |
Elsevier B.V. |
Relação |
Catalysis Today |
Direitos |
closedAccess |
Palavras-Chave | #Time-resolved XAS #MCR-ALS #PCA #Copper speciation |
Tipo |
info:eu-repo/semantics/article |