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Triazole-based MOF for the efficient solvent-free CO2 fixation reaction via cyclic carbonates synthesis

Pourya Zarshenas

The increase of greenhouse gases such as carbon dioxide (CO2) in the atmosphere causes serious climate problems. The release of CO2 by anthropogenic activity may lead to a rise in global temperature over the past several hundred years. Hence, effective methods to capture CO2 and mitigate CO2 emissions are urgently demanded. Several strategies have been attempted to reduce CO2, including physical adsorption, and chemical sequestration of CO2. In situ conversion of the captured CO2 into useful product could be the most effective method for CO2 treatment. The CO2 cycloaddition reaction is an important reaction for producing cyclic carbonate, which has a wide range of applications in many fields. Various heterogeneous catalysts have been developed for CO2 cycloaddition reactions, including metal oxides, zeolites, metal-organic frameworks (MOFs) and supported catalyst. Among these catalysts, MOFs have attracted increasing interest due to their excellent properties such as many reactive sites, large surface area, high absorption capacity and well tunable pore structures. It has been reported that MOF-5, Co-MOF-74, Mg-MOF-74, MIL-125-NH2, UiO-66-NH2, Fe-MIL-101, Cr-MIL-101, PCN-224, PCN-700, Hf-Nu-1000, MMCF-2 and MMPF-18 as catalysts can well accelerate the CO2 coupling with epoxide. In this seminar, a highly new porous and stable metal-organic framework containing both metal sites (Zr clusters as Lewis acid sites) and nitrogen rich triazole group (as Lewis base sites) was successfully synthesized via solvothermal reaction. Triazole containing MOF exhibit superior catalytic activities in solvent free CO2 cycloaddition with epoxides. It was demonstrated that the highly performance of triazole containing catalyst is due to the presence of nitrogen groups of triazole moiety which can act as Lewis base. In addition, the MOF catalyst showed excellent stability and easy recyclability in comparison with homogenous catalysts.