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

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 C-C coupling products. The hydrated sites formed in the interface of magnesia and silica remain active in the C-C 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).

Automated summary

A series of ZnO/MgO-SiO2 systems with different MgO:SiO2 ratios were studied for their catalytic performance in 1,3-butadiene production, showing that water presence can decrease C-C coupling products but hydrated sites remain active in the reaction. High 1,3-butadiene selectivity was achieved with MgO:SiO2 ratios of (1:1) and (3:1) in the catalysts.