Methanol synthesis on Cu/ZnAl2O4 and Cu/ZnOAl2O3 Catalysts. Influence of carbon monoxide pretreatment on the formation and concentration of formate species

Abstract

Chemical trapping, thermoprogrammed desorption (TPD) and FT-IR spectroscopy have been used to study the mechanism of methanol synthesis on Cu/ZnAl2O4 and Cu/ZnOAl2O3 catalysts. Pretreatment of the catalyst by carbon monoxide creates anionic vacancies and increases the amount of surface formate species. Three kinds of formate are formed as characterized by FT-IR spectroscopy and TPD. One is the formate located on copper; another, which desorbs at a temperature between copper formates and formates located on ZnAl2O4, is assumed to be formed in the vicinity of an oxygen vacancy. The third is located on ZnAl2O4. Implications of these results on the reaction mechanism are discussed. © 1990.