Spillover of CO and H sub 2 onto Al sub 2 O sub 3 surfaces

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90013-A· OSTI ID:5539877

Sen, B; Falconer, J L; Mao, Tianfu; Yu, Min; Flesner, R L ^[1]

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1. Univ. of Colorado, Boulder (USA)

Temperature-programmed reaction and desorption (TPR, TPD) for Al{sub 2}O{sub 3} physically mixed with supported Ni catalysts show directly that one of the two CH{sub 4} peaks observed previously for TPR (CO hydrogenation) on Ni/Al{sub 2}O{sub 3} catalysts results from spillover of adsorbed species onto Al{sub 2}O{sub 3} and is not due to adsorption on unreduced Ni sites. Temperature-programmed desorption from physical mixtures of Al{sub 2}O{sub 3} and 19% Ni/Al{sub 2}O{sub 3} indicates that the support-bound species is a H-CO complex, and the stoichiometry is consistent with that of a CH{sub 3}O species. The concentration of CH{sub 3}O on Al{sub 2}O{sub 3} is estimated to be approximately 1 {mu}mol/m{sup 2} Al{sub 2}O{sub 3} (350 {mu}mol/g Al{sub 2}O{sub 3}). Though CH{sub 3}O does not form on the SiO{sub 2} support of Ni/SiO{sub 2}, it does form on physical mixtures of Ni/SiO{sub 2} and Al{sub 2}O{sub 3} that were prepared to provide good contact between particles. The rate of spillover appears to increase with the closer proximity between the support and the catalyst, higher Ni surface area, and better contact between the particles, but it also depends on the Al{sub 2}O{sub 3} area available for transfer. The rate of CH{sub 3}O hydrogenation increases with Ni surface area. An unexplained loss in Ni surface area was observed with physical mixtures of Al{sub 2}O{sub 3} and catalysts that were prepared by crushing the particles while wet.

• OSTI ID: 5539877
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 126:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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