Investigation of Cu-ZnO/SiO2 catalysts for CO2 hydrogenation: Effect of SiO2 support with different porous structure

Abstract

CO2 hydrogenation is one of the reactions to realize effective utilization of CO2, while Cu-Zn based catalyst is widely adopted for CO2 hydrogenation to value-added chemicals like methanol. However, this process is less efficient since the poor performance of catalyst due to its poor dispersion or sintering issue. In this study, three kinds of SiO2 supports (SBA-15, MCM-41 and Nano-SiO2) with different porous structure were conducted to load same amount of 5.0 wt% Cu-ZnO active component (the molar ratio of Cu/Zn is 2.0), which were further applied for CO2 hydrogenation. All catalysts were characterized chemically, morphologically and structurally by different techniques such as XRD, BET, TEM, H2-TPR and CO2-TPD. The results showed that the structure of three catalysts was basically preserved and the surface aera kept stable after loading active component, while the active component had the best dispersion when SBA-15 was used as the support and space-time yield of methanol is about 705.6 gMeOH•kgCu−1•h−1,which is higher than that of Nano-SiO2-5% (532.9 gMeOH•kgCu−1•h−1) and MCM-41–5% (213.2 gMeOH•kgCu−1•h−1). Due to the confined effect of mesoporous channel structure provided by SBA-15 support, the Cu-Zn interaction could be significantly enhanced with increasement of medium and strong alkaline sites, further improving CO2 activation ability. This work provides a useful strategy to improve the catalytic efficiency of classical Cu-Zn catalyst for the CO2 hydrogenation process.