Magnesium-Promoted Catalytic Stability of the Cu/ZnO/ZrO2/Al2O3-MgO Catalyst in CO2 Hydrogenation to Methanol

Abstract

A Mg-promoted Cu/ZnO/ZrO₂/Al₂O₃ catalyst (CZZAM) was developed for methanol synthesis via CO₂ hydrogenation. Incorporating magnesium into the catalyst precursor improved the durability, addressing stability issues in our previously reported Cu/ZnO/ZrO₂/Al₂O₃ (CZZA) catalysts. Comparative evaluations showed that CZZAM outperforms commercial Cu/ZnO/Al₂O₃ (CZA) and CZZA catalysts, achieving a maximum methanol space–time yield of 0.99 g_MeOH·g_cat^–1·h^–1 with a methanol selectivity of 50.6% and a yield of 12.7% under 24,000 mL·g_cat^–1·h^–1 at 260 °C and 5 MPa. In a 60 h test, CZZAM exhibited only a 2.8% decrease in methanol productivity compared to over 9 to 10% declines for CZA and CZZA. Characterizations revealed that Mg addition enhanced Cu nanoparticle dispersion and structural stability. These findings demonstrate that Mg incorporation effectively enhances activity and stability in Cu/ZnO/ZrO₂/Al₂O₃ catalysts for CO₂ hydrogenation to methanol.