Promotional role of methanol and CO2 in carbon dioxide-rich syngas hydrogenation over slurry reactor utilizing combustion induced Cu-based catalysts

Converting CO 2 to methanol directly remains a hurdle due to catalyst and thermodynamic limitations. This study proposes a solution: using Cu–MgO–CeO 2 (CuMgCe) catalysts (synthesized by solvent combustion) in slurry reactors for methanol formation through methanol-assisted CO 2 -rich syngas hydrogenation. The key innovation lies in the catalyst design by focusing on CO 2 -rich syngas mixtures, we establish a crucial link between catalyst structure and its activity (structure-activity relationship). Our CuMgCe catalyst achieves a space-time yield of 646 g MeOH /kg cat -h −1 , exceeding lab-made industrial catalysts (608.5 g MeOH /kg cat -h −1 ). This yield is further boosted by 5% through an ingenious method - adding initial methanol, which promotes formate intermediates for enhanced productivity. In-depth analysis reveals CO 2 formation during CO-TPD-MS and CO-TPR-MS, generating highly active surface species (CO 2 δ− ) ideal for forming formate intermediates. In-situ DRIFTS confirms the dominance of this formate pathway on CuMgCe for selective methanol synthesis. A mechanistic study sheds light on the synergistic effect of MgO and CeO 2 in the lab-prepared CuMgCe catalyst. This synergy promotes methanol formation during CO 2 -cofed syngas conversion. This research paves the way for highly efficient and selective catalysts for CO 2 utilization in slurry reactor technology, offering a significant step towards cleaner fuel production. • The CuMgCe is more active for CO 2 -rich syngas to methanol than CuZnCe and CuZnMg. • Oxygen vacancies are responsible for CO oxidation to CO 2 . • The in-situ DRIFTS confirmed the Formate pathway for CO 2 hydrogenation to methanol. • The autocatalytic pathways increased the STY of methanol by 5%. • The CO and CO 2 adsorption are more favorable on Cu/MgO and Cu/CeO 2 , respectively.