Preparation of CuO/ZnO/Al 2O 3 catalysts for methanol synthesis using parallel-slurry-mixing method

Abstract

A series of CuO/ZnO/γ-Al 2O 3 catalysts with different Al 2O 3 contents were prepared using the parallel-slurry-mixing method, in which an aqueous solution of Cu 2+ and Zn 2+ mixed nitrates and an aqueous solution of Na 2CO 3 were poured into a precipitation vessel containing γ-Al 2O 3 slurry in a parallel-flow manner. The catalyst structure and its performance for methanol synthesis were investigated. The results indicated that Al 2O 3 as a structural promoter can inhibit CuO and ZnO crystallites from enlarging during calcination. The catalyst with a Cu/Zn/Al ratio of 4/5/1 (molar ratio) exhibits the highest catalytic activity. With an increase in Al content, the amount of (Cu 0.3Zn 0.7) 5(CO 3) 2(OH) 6 phase in the catalyst precursor before calcination decreases, whereas that of Cu 2CO 3(OH) 2 phase increases; (Cu 0.3Zn 0.7) 5(CO 3) 2(OH) 6 in the precursor is beneficial to the catalytic activity of the final Cu/ZnO/γ-Al 2O 3 catalyst.