Coupling reaction between ethanol dehydrogenation and maleic anhydride hydrogenation catalyzed by Cu/Al2O3, Cu/ZrO2, and Cu/ZnO catalysts

Abstract

Cu/MOx (MOx=Al2O3, ZrO2, and ZnO) catalysts were prepared by incipient wetness impregnation method. Al2O3, ZrO2, and ZnO crystallites existed in both calcined and reduced Cu/MOx catalysts. After reduction, CuO were reduced to Cu0, which was considered as an active site in both ethanol dehydrogenation and maleic anhydride hydrogenation. The basicities of Cu/MOx catalysts were in the order of Cu/Al2O3>Cu/ZrO2>Cu/ZnO. The coupling reaction between ethanol dehydrogenation and maleic anhydride hydrogenation catalyzed by Cu/MOx catalysts was carried out at reaction temperatures ranging from 240 to 300°C. In the coupling reaction, Cu/ZrO2 and Cu/ZnO catalysts with large crystallite-sized Cu0 nanoparticles favored the dehydrogenation of ethanol to acetaldehyde with the maximum selectivity of 67.6% and the hydrogenation of diethyl maleate to diethyl succinate with the maximum selectivity of 99.6%. Cu/Al2O3 catalysts with small crystallite-sized Cu0 nanoparticles favored the dehydrogenation of ethanol to ethyl acetate and the hydrogenation of diethyl succinate to γ-butyrolactone with the maximum selectivity of 95.4% at maleic anhydride conversion of 98% and 300°C. The Cu/MOx catalysts also favored the dehydration of ethanol to n-butanol due to their basicity. Coupling ethanol dehydrogenation and maleic anhydride hydrogenation had good compensation for both reaction heat and hydrogen.