Issue 21, 2010

In situ time-resolved DXAFS for the determination of kinetics of structural changes of H-ZSM-5-supported active Re-cluster catalyst in the direct phenol synthesis from benzene and O2

Abstract

Dynamic structural changes and their kinetics of a Re10-cluster catalyst in the direct phenol synthesis from benzene and O2 were investigated by in situ time-resolved Re LIII-edge energy-dispersive XAFS (DXAFS). We have successfully monitored the structural transformation of active Re10 clusters to inactive Re monomers in the course of the selective oxidation of benzene with O2 on the catalyst by the DXAFS technique in a real time. The results obtained suggested that the Re10 cluster transformed directly to the Re monomers, which showed first order kinetics with respect to the quantity of Re10 clusters. The absence of undesirable intermediate structures with low phenol selectivity during the structural transformation may be an advantageous issue for the high phenol selectivity of 93.9% at 9.9% conversion in a pulse reaction and 87.7% at 5.8% conversion in a steady-state reaction on the Re10-cluster catalyst. The reactant benzene inhibited the unfavorable structural transformation of the Re10 cluster to the Re monomers during the selective benzene oxidation to phenol.

Graphical abstract: In situ time-resolved DXAFS for the determination of kinetics of structural changes of H-ZSM-5-supported active Re-cluster catalyst in the direct phenol synthesis from benzene and O2

Article information

Article type
Paper
Submitted
13 Jan 2010
Accepted
09 Mar 2010
First published
06 Apr 2010

Phys. Chem. Chem. Phys., 2010,12, 5701-5706

In situ time-resolved DXAFS for the determination of kinetics of structural changes of H-ZSM-5-supported active Re-cluster catalyst in the direct phenol synthesis from benzene and O2

M. Tada, Y. Uemura, R. Bal, Y. Inada, M. Nomura and Y. Iwasawa, Phys. Chem. Chem. Phys., 2010, 12, 5701 DOI: 10.1039/C000843P

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