Catalytic Activity of Bimetallic Cu-Ag/MgO-SiO2 Toward the Conversion of Ethanol to 1,3-Butadiene

In the present work, the catalytic conversion of ethanol to 1,3-butadiene (1,3-BD) was studied over monometallic of Cu and Ag, and bimetallic Cu-Ag supported on MgO-SiO2 (with MgO/SiO2 ratio of 2.0) under the temperature range from 250 to 325 degrees C. All catalysts were prepared by 4 different techniques including (i) conventional impregnation, (ii) microwave-assisted method, (iii) polyvinyl alcohol/sodium borohydride (PVA/NaBH4) assisted method, and (iv) benzoxaxine-assisted method to elucidate the effect of catalyst preparation method on their catalytic performance. All fresh and spent catalysts were also characterized by X-ray diffraction (XRD), N-2 adsorption and Temperature-programmed reduction (TPR) techniques to understand the relation between their physical/chemical properties and catalytic performance. From the reaction test, it was found that 5% Ag/MgO-SiO2 showed greater activity towards 1,3-BD production than 5% Cu/MgO-SiO2; nevertheless, higher deactivation after 6 h of operation was observed from 5% Ag/MgO-SiO2. Importantly, this study revealed that bimetallic 2.5%Cu-2.5%Ag/MgO-SiO2 enhanced significantly higher activity and stability towards the reaction than monometallic catalysts. In addition, 2.5%Cu-2.5%Ag/MgO-SiO2 prepared by benzoxaxine-assisted method enhanced significantly higher reaction activity and stability than other preparation techniques, from which 1,3-BD yield of 46.40% after 6 h of operation can be achieved. From the characterization, the good activity of this catalyst is mainly due to the dispersion improvement of metal over MgO-SiO2 support.