Synthesis of methanol and dimethyl ether from the CO2 hydrogenation over Cu·ZnO supported on Al2O3 and Nb2O5

Abstract

We report the synthesis, characterization and catalytic evaluation of Cu·ZnO catalysts supported on Al2O3 and Nb2O5, as acidic materials, to study the CO2 hydrogenation to methanol and dimethyl ether. The catalysts were prepared by precipitation or impregnation of the metals over the supports. They were characterized by different techniques, such as XRF, BET area, TPD of n-butylamine, XRD and TPR. Catalytic tests were performed in an automated catalytic unit coupled to a gas chromatograph with FID and TCD detectors. Different conditions of temperature and pressure were studied. It could be observed that the choice of the synthesis method affects the activity and selectivity of the CO2 hydrogenation, at the conditions used in this work. The catalyst prepared by impregnation of the metals over the Al2O3 support was the most active and selective to dimethyl ether. This result can be explained by the better and lower temperature reducibility of CuO particles along with higher density of acid sites and strength of the alumina support.