Formation and decomposition of methoxy species on a Ni/Al sub 2 O sub 3 catalyst

Journal Article · Thu Jan 31 23:00:00 EST 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90195-A· OSTI ID:5517237

Chen, B; Falconer, J L ^[1]; Chang, L ^[2]

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1. Univ. of Colorado, Boulder (USA)
2. Tianjin Univ. (China)

Temperature-programmed reaction and desorption (TPR, TPD) were combined with isotope exchange to study the forward and reverse spillover of CO on a 5.1% Ni/Al{sub 2}O{sub 3} catalyst. Carbon monoxide adsorbs nondissociatively on Ni at 300 K, but a fraction of adsorbed CO dissociates at 425 K. Carbon monoxide on Ni, in the presence of H{sub 2} at elevated temperature, spills over to form CH{sub 3}O on Al{sub 2}O{sub 3}. This CH{sub 3}O can undergo reverse spillover to form both CO and carbon on Ni. For low CH{sub 3}O coverages, mostly carbon forms, but at higher CH{sub 3}O coverages, mostly CO forms on Ni. The reverse spillover is faster at higher temperatures, for longer times, and for higher DH{sub 3}O coverages. The rate of reverse spillover is comparable to the rate of CH{sub 3}O hydrogenation, and reverse spillover may be the limiting step in CH{sub 3}O hydrogenation. The rate of carbon hydrogenation on Ni is significantly inhibited by the presence of CO adsorbed on Ni, perhaps because H{sub 2} adsorption sites are blocked.

• OSTI ID: 5517237
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 127:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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CARBON MONOXIDE
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