Enhanced catalytic activity of metal-doped Cu/ZnO/Al2O3 catalyst incorporated polyethylene glycol for CO2 hydrogenation to methanol

Abstract

The increasing concerns over greenhouse gas emissions have driven significant research into sustainable carbon utilization strategies. Among these, the catalytic hydrogenation of CO₂ to methanol has emerged as a promising approach, offering both carbon capture and value-added chemical production. In this study, a Cu/ZnO/Al₂O₃ (CZA) catalyst was synthesized via an enhanced co-precipitation method with adding polyethylene glycol (PEG) surfactant to improve porosity and surface functionality. Additionally, Ga and Ti were introduced as promoters to enhance catalytic performance. Catalytic performance tests demonstrated that the Ti-doped CZA catalyst (Ti-CZA-3PG) exhibited the highest CO₂ conversion (35.6 %) and space-time yield (STY) of methanol (312.6 mmol/(g_cat∙h)) at 280 °C under 50 bar, even outperforming a commercial catalyst. The improved performance is attributed to enhanced Cu-ZnO interaction, increased active sites due to oxygen vacancies, and suppression of the reverse water-gas shift reaction, ensuring higher methanol selectivity. This study highlights the synergistic effects of PEG-assisted synthesis and hetero-metal doping, presenting an effective strategy for optimizing Cu-based catalysts for CO₂ hydrogenation to methanol.