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Rapid monitoring of the nature and interconversion of supported catalyst phases and of their influence upon performance: CO oxidation to CO2 by γ-Al2O3 supported Rh catalysts

DOI: 10.1002/chem.200500644 DOI Help
PMID: 16402395 PMID Help

Authors: Mark A. Newton (The European Synchrotron Radiation Facility) , Andrew J. Dent (Diamond Light Source) , Sofia Diaz-Moreno (Diamond Light Source) , Steven G. Fiddy (CLRC Daresbury Laboratory) , Bhrat Jyoti (University of Southampton) , John Evans (University of Southampton; Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry - A European Journal , VOL 12 (7) , PAGES 1975-1985

State: Published (Approved)
Published: February 2006

Abstract: Spatially and temporally resolved energy-dispersive EXAFS (EDE) has been utilised in situ to study supported Rh nanoparticles during CO oxidation by O2 under plug-flow conditions. Three distinct phases of Rh supported upon Al2O3 were identified by using EDE at the Rh K-edge during CO oxidation. Their presence and interconversion are related to the efficiency of the catalysts in oxidising CO to CO2. A metallic phase is only found at higher temperatures (>450 K) and CO fractions (CO/O2>1); an oxidic phase resembling Rh2O3 dominates the active catalyst under oxygen-rich conditions. Below about 573 K, and in CO-rich environments, high proportions of isolated RhI(CO)2 species are found to co-exist with metallic Rh nanoparticles. Alongside these discrete situations a large proportion of the active phase space comprises small Rh cores surrounded by layers of active oxide. Confinement of Rh to nanoscale domains induces structural lability that influences catalytic behaviour. For CO oxidation over Rh/Al2O3 there are two redox phase equilibria alongside the chemistry of CO and O adsorbed upon extended Rh surfaces.

Journal Keywords: Exafs Spectroscopy; Heterogeneous Catalysis; Microreactors; Oxidation; Rhodium

Subject Areas: Chemistry

Facility: ID24 at ESRF

Added On: 10/11/2010 08:43

Discipline Tags:

Physical Chemistry Catalysis Chemistry

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