Carbonylation of methanol to methyl acetate over Cu/TiO2-SiO2 catalysts: Influence of copper precursors

Abstract

In the present study, three kinds of copper/titania-silica mixed oxides (Cu/TS) catalysts were prepared using copper chloride, copper nitrate, and copper acetate as copper precursors by the sol-gel method. The catalytic performance was tested in the vapor phase carbonylation of methanol free of halide. The characterization results showed that the interaction between copper and support was the strongest on the 10Cu/TS (Cl) catalyst, leading to the highest copper dispersion and the most surface Cu+ species. As a result, the 10Cu/TS (Cl) catalyst obtained the largest absorption capacity of CO and the maximum amount of Lewis acid sites. The catalytic performance results showed that the space time yield (STY) of methyl acetate (MA) was positively correlated with the content of surface Cu+ species and the specific surface area of the Cu+ cations (SCu(I)). Therefore, the 10Cu/TS (Cl) catalyst obtained the highest STYMA of 1.619 mol/h.kgcat. Moreover, the STYMA per Cu+ site was inversely proportional to the copper particle size, indicating that the carbonylation of methanol to MA is a structure-sensitive reaction. And the methanol conversion was positively correlated with the amount of surface acid sites. Furthermore, the active sites for the synthesis of methyl formate and dimethyl ether were also studied.