Multivariate curve resolution analysis applied to time-resolved synchrotron X-ray Absorption Spectroscopy monitoring of the activation of copper alumina catalyst

Autor(es)

Cassinelli, Wellington H. ^[1] ; Martins, Leandro ^[1] ; Passos, Aline R. ^{[2, 1]} ; Pulcinelli, Sandra H. ^[1] ; Santilli, Celso V. ^[1] ; Rochet, Amelie ^[2] ; Briois, Valerie ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, UNESP, Inst Quim, BR-14800900 Araraquara, SP - Brazil

^[2] Synchrotron SOLEIL, F-91192 Gif Sur Yvette - France

• Tipo de documento: Artigo Científico
• Fonte: CATALYSIS TODAY; v. 229, p. 114-122, JUN 15 2014.
• Citações Web of Science: 43

Resumo

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. (AU)

• Processo FAPESP: 07/53073-4 - Cerâmicas mesoporosas e hibridos orgânico-inorgânicos multifuncionais preparados pelo processo sol-gel
• Beneficiário: Celso Valentim Santilli
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/50023-7 - Combinação de técnicas espectrópicas resolvidas no tempo aplicadas ao estudo estrutural de catalisadores com porosidade hierárquica
• Beneficiário: Leandro Pierroni Martins
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/05346-2 - E-MRS 2013 Spring Meeting
• Beneficiário: Wellington Henrique Cassinelli
• Modalidade de apoio: Auxílio à Pesquisa - Reunião - Exterior