The effect of zirconia as a promoter on Cu/MOF-5 catalysts for CO2 hydrogenation to methanol

•The physiochemical properties of the modified catalysts, and temperature influence the catalytic activity.•The methanol selectivity increases with increasing zirconium promoter.•The high pressure increases the conversion of CO2 and decreases the selectivity to methanol. The rise in carbon dioxide concentration is a primary anthropogenic source of severe climate change and ecological issues. Catalytic hydrogenation of CO2 into value-added chemicals and fuels including methanol is one of the attractive environmentally friendly ways to valorize carbon-containing feedstock and reduce global CO2 emissions. However, enhancing catalytic activity to achieve high methanol yield and selectivity while maintaining stability remains a major challenge. This study investigated the promotion of Cu/MOF-5 catalysts with varying loadings of ZrO₂ to determine its effects on catalytic performance in CO₂ hydrogenation. The copper loading was kept constant while the ZrO₂ content on the MOF-5 support was varied via the impregnation method. The addition of ZrO₂ was found to influence the BET surface area, suggesting the presence of amorphous ZrO₂, as its crystalline phases were not detected in x-ray diffractograms. Catalytic results demonstrated that ZrO₂ addition enhanced the catalytic activity, with increased CO₂ conversion up to 13.2 %. The results showed a correlation between catalytic performance and the reducibility of the active metal, driven by the amount of ZrO₂ present. The catalyst with the highest ZrO₂ loading exhibited the best performance, attributed to its increased surface area and enhanced reducibility. Under optimized conditions (GHSV of 1350 h⁻¹, temperature of 200 °C, and pressure of 30 bar), the catalyst achieved 100 % methanol selectivity. This study underscores the significant role of ZrO₂ as a promoter in enhancing the activity and selectivity of Cu/MOF-5 catalysts, providing critical insights into the design of efficient catalytic systems for CO₂ hydrogenation.