Effect of Cerium Addition on the Catalytic Performance of Cu-Fe/SiO<sub>2</sub> for the Synthesis of Lower Alcohols from Syngas

Abstract

A series of Ce-Cu-Fe/SiO2 catalysts with different Ce contents (mole fraction relative to SiO2, 0-20%) were prepared by co-impregnation and their catalytic performances for CO hydrogenation to lower alcohols were investigated using a continuous flow fixed bed micro-reactor. These catalysts were characterized by X-ray diffraction (XRD), N2-adsorption, temperature-programmed reduction of H2 (H2-TPR), Fourier transform infrared of CO adsorption (CO-FTIR), and temperature-programmed desorption of CO (CO-TPD). The results showed that the addition of an appropriate amount of Ce decreased the Cu crystal size and promoted the dispersion of Cu, which greatly increased the amount of adsorbed CO. Additionally, the interaction of doped Ce with Cu increased the associative and dissociate adsorption capacity of CO, which is favorable for the formation of CHx and the insertion reaction of adsorbed CO to CHx. Both the activity and alcohol selectivity of the Cu-Fe/SiO2 catalyst increased under the combined effect of the above-mentioned two aspects. At a Ce content of 10%, the space time yield of lower alcohols improved from 58.0 g·kg - 1 ·h - 1 over the Cu-Fe/SiO2 catalyst to 121.0 g·kg - 1 ·h - 1 over the Ce-Cu-Fe/SiO2 catalyst at 250 °C, a pressure of 3.0 MPa, a H2/CO molar ratio of 2, and gas hourly space velocity of 6000 mL·g - 1 ·h - 1 .