Effects of altervalent cation doping of TiO[sub 2] on kinetic parameters of CO hydrogenation and CO oxidation on supported Rh

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1994.1059· OSTI ID:7233147

Ioannides, T; Verykios, X E; Tsapatsis, M; Economou, C ^[1]

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1. Univ. of Patras (Greece)

The reactions of CO hydrogenation and CO oxidation over Rh are used to determine the influence of altervalent cation doping of a TiO[sub 2] support on kinetic parameters. Rh crystallites are dispersed on TiO[sub 2] doped with W[sup 6+] cations at concentration levels up to 0.67 at%. It is shown that turnover frequencies of CO hydrogenation increase monotonically with increasing dopant content in the TiO[sub 2] matrix, apparent activation energy is reduced, and selectivity shifts towards smaller-chain saturated hydrocarbons. Turnover frequencies of CO oxidation at low CO/O[sub 2] ratios are shown to pass through a maximum with increasing W[sup 6+] dopant content of TiO[sub 2]. A small activity enhancement is observed at higher CO pressures. The apparent activation energy is found to vary with W[sup 6+] content. It is proposed that charge transferred from the doped semiconducting carrier to the metal crystallites alters the chemical potential of the crystallites and, therefore, the work function of surface metal atoms, while a strong electrostatic field is caused by the dipole developed at the metal-semiconductor interface. As a result, the mode of H[sub 2] and CO adsorption is altered, as well as the intrinsic kinetic parameters of the reactions investigated. 28 refs., 6 figs., 6 tabs.

• OSTI ID: 7233147
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 145:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

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