In Situ Structure-Function Studies of Oxide Supported Rhodium Catalysts by Combined Energy Dispersive XAFS and DRIFTS Spectroscopies
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
- Diamond Light Source, Chilton, Didcot, OX11 0DE (United Kingdom)
- CCLRC Daresbury Laboratory, Warrington, WA4 4AD (United Kingdom)
- ESRF, Grenoble, F-38043 (France)
The techniques of energy dispersive EXAFS (EDE), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and mass spectrometry (MS) have been combined to study the structure and function of an oxide supported metal catalyst, namely 5 wt% Rh/Al2O3. Using a FreLoN camera as the EDE detector and a rapid-scanning IR spectrometer, experiments could be performed with a repetition rate of 50 ms. The results show that the nature of the rhodium centers is a function of the partial pressures of the reacting gases (CO and NO) and also temperature. This combination of gases oxidizes metallic rhodium particles to Rh(CO)2 at room temperature. The proportion of the rhodium adopting this site increases as the temperature is raised (up to 450 K). Above that temperature the dicarbonyl decomposes and the metal reclusters. Once this condition is met, catalysis ensues. Gas switching techniques show that at 573 K with NO in excess, the clusters can be oxidized rapidly to afford a linear nitrosyl complex; re-exposure to CO also promotes reclustering and the CO adopts terminal (atop) and bridging (2-fold) sites.
- OSTI ID:
- 21054693
- Journal Information:
- AIP Conference Proceedings, Vol. 882, Issue 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644606; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION SPECTROSCOPY
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSIS
CATALYSTS
FINE STRUCTURE
FOURIER TRANSFORM SPECTROMETERS
FOURIER TRANSFORMATION
GASES
INFRARED SPECTRA
INTERFACES
MASS SPECTROSCOPY
NITRIC OXIDE
OXIDATION
PARTIAL PRESSURE
RHODIUM
STRUCTURE FUNCTIONS
X-RAY SPECTROSCOPY