Facile Preparation of Cu-Al Oxide Catalysts and Their Application in the Direct Synthesis of Ethanol from Syngas

A simplified catalytic system K-Cu/Al2O3 (KCA-xCu-T) with Cu-Al oxides was prepared by a facile impregnation method and was successfully applied in the direct synthesis of ethanol from syngas. The results demonstrated that the distribution of CuO, CuAl2O4, and CuAlO2 in KCA-xCu-T catalysts can be effectively tuned by varying the calcination temperature (T/degrees C) and CuO loading (xCu/wt%). The cooperative effect between Cu-0 and CuAlO2(Cu+) was proved to be responsible for the enhanced ethanol selectivity. Furthermore, the formation of CuAlO2 could efficiently fix Cu+ species in KCA-10Cu-900 sample, and thus lead to excellent catalytic stability (300h at 400 degrees C). CuAl2O4 itself has no catalytic effect but can be gradually decomposed into Cu+ and/or Cu-0 species during reaction, which further influenced the ethanol selectivity (38.4wt%).