Preparation and Characterization of Ni-based Catalysts Supported on Metal Organic Frameworks (MOFs) for CO2 Conversion to Value-added Chemicals

Abstract

 This research is aimed at producing Metal Organic Frameworks (MOFs) for the conversion of CO₂ to value-added chemicals using two organic linkers namely; Terephthalic acid and Triazole. Two different MOFs materials were produced via solvent-free and solvothermal synthesis. The MOFs materials were impregnated with Ni²⁺ to produce their respective Ni-based catalysts. Fourie-Transform Infrared (FTIR) characterization of MOFs and Ni-catalyst prepared via solvothermal synthesis shows absorption bands in the range of 628cm^-1–689cm^-1 corresponding to O-Ni-O and Ni-N vibration, indicating the formation of coordinate bond between –COOH, -NH groups and Ni²⁺. X-Ray diffractograms (XRD) of the prepared MOFs revealed crystalinity with different average crystallite sizes; MOF-terephthalic acid (137.9nm), catalyst-terephthalic acid (149.9nm), MOF-triazole (155.3nm) and catalyst-triazole (2.200nm) at 2θ values of 8.616550, 8.988520, 10.51650, and 33.24290 respectively. The morphologies and particle sizes of the materials were evaluated by scanning electron microscope (SEM) which reveals the flake-like shape (MOF-terephthalic acid), cuboid shape (catalyst-terephthalic acid) and rhombohedral shape for mof-triazole and catalyst-triazole respectively. The terephthalic-based materials are found to exhibit less particle sizes (213.651-228.242nm) relative to triazole-based materials (242.591-683.093nm). It was observed that the crystalinity, crystallite size and particle size of the materials increases with the impregnation of Ni²⁺ into the frameworks. In conclusion, the solvothermal synthesis approach adopted in this study proved to be more efficient than the solvent-free synthesis in producing materials with excellent properties for the conversion of CO₂ to value-added chemicals.