1,3-Butadiene production from aqueous ethanol over ZnO/MgO-SiO2 catalysts: Insight into H2O effect on catalytic performance

Abstract

A series of ZnO/MgO-SiO2 systems have been prepared and characterized by one-pass temperature-programmed desorption of CO2, NH3 and H2O, FTIR spectroscopy with adsorbed pyridine and CO2, temperature programmed surface reaction of ethanol and isopropanol, and reaction of isopropanol conversion. Effect of MgO:SiO2 ratio in the catalysts on catalytic performance in 1,3-butadiene production from aqueous ethanol have been investigated. The results indicate that hydrophilicity of ZnO/MgO-SiO2 are determined by MgO:SiO2 ratio, and chemisorption of water occurs preferably on Mg-containing sites. The presence of water in the initial ethanol leads to a decrease in formation of the CC coupling products. The hydrated sites formed in the interface of magnesia and silica remain active in the CC coupling reaction even in the presence of water. 1,3-Butadiene selectivity >60 % in the conversion of aqueous ethanol (80 vol%) is achieved in the presence of ZnO/MgO-SiO2 catalysts with the ratio of MgO:SiO2 = (1:1) and (3:1).