Cu/ZnO/Al2O3 Catalyst Promoted with Amorphous MgO for Enhanced CO2 Hydrogenation to Methanol

Abstract

CO₂ hydrogenation to methanol not only reduces CO₂ emissions but also produces a high-quality energy source that is easy to store and transport. We found that the Cu/ZnO/Al₂O₃/MgO catalyst prepared by the deposition-precipitation method, exhibits a higher methanol space-time yield compared to the Cu/ZnO/Al₂O₃ catalyst below 2 MPa. However, no activity difference was observed beyond 2 MPa. Characterization techniques revealed that for the Cu/ZnO/Al₂O₃/MgO catalyst, MgO is amorphous attributed to the influence of Al during calcination. The presence of amorphous MgO not only reduces the size of Cu⁰ particles but also enhances CO₂ adsorption on the catalyst surface. We also demonstrate that improvement of CO₂ adsorption capacity is the key factor for the higher activity of the Cu/ZnO/Al₂O₃/MgO catalyst below 2 MPa.