Abstract
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•Green synthesis of methanol over mesoporous silica Pd nano-catalysts.•Application of slurry reactor to study promoting role of Pd catalysts.•Degree of crystallinity and dispersion were observed as driven forces for high performance catalysts.
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.