Highly active and selective Cu-ZnO based catalyst for methanol and dimethyl ether synthesis via CO2 hydrogenation

Abstract Highly active and selective Cu-ZnO based catalysts with high BET surface areas and Cu surface areas were prepared using the co-precipitation method. The Cu-ZnO based catalysts were systematically characterized and studied for methanol synthesis. Bifunctional catalysts, composed of Cu-ZnO based catalysts and HZSM-5 were studied for one-step dimethyl ether (DME) synthesis via CO 2 hydrogenation. The effects of catalyst preparation conditions, reaction temperature, and pressure on methanol and DME synthesis were investigated and the optimum reaction conditions were determined. The optimized catalyst showed a BET surface area of 128 m 2 /g and a Cu surface area of over 59.3 m 2 /g, and demonstrated a high catalytic activity for CO 2 hydrogenation. A bifunctional catalyst, prepared by a synthesized Cu-ZnO catalyst and HZSM-5, showed a high DME selectivity in one-step CO 2 hydrogenation and methanol dehydration. The high activity and selectivity of the catalysts were attributed to the microstructure of the catalysts, which can be greatly affected by the catalyst preparation process. A long-term stability test showed a considerable decrease in activity within the first 20 h; however, the CO 2 conversion (21.4%) and DME selectivity (55.5%) were still very high after 100 h.