Low temperature green methanol synthesis by CO₂ hydrogenation over Pd/SiO₂ catalysts in slurry reactor

The utilization of the greenhouse gas of carbon dioxide (CO₂) for fuel and value-added chemicals synthesis has become globally indispensable process for healthy environment. In this context, the hydrogenation of CO₂ to methanol is an attractive avenue for achieving such goal. Thus, we prepared mesoporous silica-supported nanocrystalline palladium metal (Pd) for methanol synthesis by CO₂ hydrogenation. To investigate the role of Pd metal, the synthesized mesoporous silica was loaded with 1, 2, 3 and 4 wt% of Pd. Physicochemical profile of synthesized mesoporous silica supported Pd catalysts were assessed by Inductively coupled plasma - optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), Nitrogen adsorption–desorption and Temperature Program Reduction (TPR) techniques. ICP-OES measurement confirmed the actual Pd metal loading on the mesoporous silica support. XRD confirmed amorphous and crystalline nature of mesoporous silica and Pd metal, respectively. FESEM images exhibited homogenous and well dispersed Pd metal particles on the surface of mesoporuse silica support. Nitrogen adsorption desorption studies displayed enlargement in BET surface area with Pd promotion. Reduction behaviour of PdO was revealed by TPR data over the studied temperature range. The structure–activity studies suggested the degree of Pd crystallinity and higher dispersions as amongst the main factors contributing to the performance of Pd/SiO₂ catalysts for pure CO₂ hydrogenation in slurry reactor.