Hydrogen exchange with adsorbed methanol and methoxy on nickel/alumina
- Univ. of Colorado, Boulder, CO (United States)
Hydrogen isotope exchange with adsorbed CH{sub 3}OH and coadsorbed CO + H{sub 2} (which form CH{sub 3}O) was studied on a Ni/Al{sub 2}O{sub 3} catalyst by temperature-programmed reaction and desorption (TPR, TPD). Since both CH{sub 3}OH and CH{sub 3}O are adsorbed on the Al{sub 2}O{sub 3} support, but H{sub 2} adsorbs and dissociates on the Ni surface, H atom spillover onto the Al{sub 2}O{sub 3} surface is an important step in the exchange process. Hydroxyl hydrogens in CH{sub 3}OH exchange orders of magnitude more rapidly than methyl hydrogens, and both types of exchange are faster than CH{sub 3}OH hydrogenation to CH{sub 4}. Thus, TPR, allows these processes to be separated in time, and exchange during TPR also allows different adsorbed species to be distinguished. Coadsorbed CO + H{sub 2} exhibit two exchange processes, one of which is different from those observed for adsorbed CH{sub 3}OH. These differences demonstrate that CH{sub 3}OH and CO + H{sub 2} do not form identical species on Al{sub 2}O{sub 3}. Coadsorption of CO + H{sub 2} forms H on Al{sub 2}O{sub 3} in addition to CH{sub 3}O, and this H results in an H{sub 2} TPD peak in addition to H{sub 2} that forms from CH{sub 3}O decomposition. Exchange is inhibited significantly by CO adsorbed on Ni, apparently because CO blocks H{sub 2} adsorption sites. 15 refs., 12 figs., 1 tab.
- OSTI ID:
- 47975
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 150; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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