One-Step Synthesis of Dimethyl Ether from CO2 Hydrogenation by Cu/Zn-BTC Derivatived CuZnO/HZSM-5 Bifunctional Catalysts

Direct synthesis of dimethyl ether (DME) from carbon dioxide (CO 2 ) hydrogenation by using bifunctional catalysts has attracted much attention in view of CO 2 conversion and utilization. However, direct CO 2 hydrogenation to DME is challenging due to kinetics and thermodynamic limitations, thus requiring the development of more effective bifunctional catalysts. In this work, metal-organic framework (MOF) Cu/Zn-BTC derived CuZnO catalyst is developed and combined with HZSM-5 for direct CO 2 hydrogenation to DME. The influence of Si/Al ratio of HZSM-5, mass ratio of CuZnO and HZSM-5, reaction temperature, reaction pressure and space velocity on the catalytic performances of the CuZnO/HZSM-5 bifunctional catalysts is systematically examined in a fixed-bed reactor. Attributing to a high activity of the Cu/Zn-BTC derived CuZnO catalyst for CO 2 hydrogenation to methanol, the CuZnO/HZSM-5 bifunctional catalysts display high CO 2 conversion and DME selectivity. Under a mild reaction condition (225 °C and 3.0 MPa), a high CO 2 conversion of 54.3% and DME selectivity of 79.5% are obtained for the bifunctional catalysts, which outperform the state-of-the-art catalysts for CO 2 hydrogenation to DME. Further, after 100 h of reaction, the bifunctional catalyst can still maintain a high CO 2 conversion rate (~ 52.6%) and DME selectivity (~ 77.3%), which suggests promising prospects for industrial applications.