Promotion effects of titanium on partial oxidation of methanol over vanadium pentoxide catalysts

This article reports studies on the catalytic activity of V2O5 coprecipitated with different TiO2 concentrations, and on the chemical characterization of the fresh and used catalysts by the following methods of chemical analyses: EDAX, XRD, FTIR, SEM, BET, TPR, and XPS. Catalytic tests were performed under integral and differential conditions. In the former (integral) series of experiments, formaldehyde, methyl formate, methylal, and CO were obtained as major products of methanol partial oxidation. A minor production of CO2 and dimethyl ether was noticed as well. Under the latter (differential) conditions, the results led to the notion of catalytic activity (reaction rate) dependence on the surface concentration of vanadium. From calculation of the turnover frequencies, it was concluded that both the catalytic activity and the HCHO production decrease with stronger V=O bonds. In turn, the reactivity of those species was influenced by addition of TiO2. (C) 1996 Academic Press, Inc.