The paper covered preparations and characterisations of Ni-Ga based catalysts including Ni-Ga alloy, Ni-Ga/mixed oxides, Ni-Ga/ mesosilica and Ni-Ga-Co/mesosilica for synthesis of methanol from direct reduction of CO2 under hydrogen. The Ni-Ga alloy and Ni-Ga/ mixed oxides were prepared by metal melting method established at 1500o C and co-condensation-evaporation method at 80o C for 24 hours, respectively. The Ni-Ga/mesosilica and Ni-Ga-Co/mesosilica catalysts were both prepared by wet impregnation method at room temperature for 24 hours. The dried white powders obtained from the co-condensation-evaporation and the impregnation procedures were contacted with NaBH4 /ethanol solution for reducing metal cations to alloy state at room temperature. Investigations on conversion of CO2 showed that the Ni-Ga/mesosilica and the Ni-Ga-Co/mesosilica catalysts behaved as the best candidates for the process when showing its high conversion of CO2 and selectivity of methanol at high pressure of 35 bars. Especially, the Ni-Ga-Co/mesosilica showed considerable activity and selectivity in the process established at a low pressure of 5 bars. Techniques such as Small Angle X-Ray Diffraction (SAXRD), Wide Angle X-Ray Diffraction (WAXRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform - Infrared Spectroscopy (FT-IR) and X-Ray Photoelectron Spectroscopy (XPS) were applied for characterising the catalysts, and Gas Chromatography (GC) coupled Thermalconductivity detector (TCD) and Flame ionized detector (FID) were used for determining the gas reactants and products.
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