Lewis acidity as an explanation for oxide promotion of metals: implications of its importance and limits for catalytic reactions

A. B. Boffa, C. Lin, A. T. Bell, G. A. Somorjai

研究成果: Article同行評審

84 引文 斯高帕斯(Scopus)

摘要

Sub-monolayer quantities of metal oxides are found to influence CO hydrogenation, CO2 hydrogenation, acetone hydrogenation, ethylene hydroformylation, ethylene hydrogenation, and ethane hydrogenolysis over Rh foils. The metal oxides investigated include AlOx, TiOx, VOx, FeOx, ZrOx, NbOx, TaOx, and WOx. Only those reactions involving the hydrogenation of C-O bonds are enhanced by the oxide overlayers. The coverage at which maximum rate enhancement occurs is approximately 0.5 ML for each oxide promoter. Titanium, niobium, and tantalum oxides are the most effective promoters. XPS measurements after reaction show that of the oxides studied titanium, niobium, and tantalum oxide overlayers are stable in the highest oxidation states. The trend in promotion effectiveness is attributed to the direct relationship between oxidation state and Lewis acidity. For the oxide promoters, bonding at the metal oxide/metal interface between the O-end of adsorbed CO and the Lewis acidic oxide is postulated to facilitate C-O bond dissociation and subsequent hydrogenation.

原文English
頁(從 - 到)243-249
頁數7
期刊Catalysis Letters
27
發行號3-4
DOIs
出版狀態Published - 1994 九月 1

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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