| Converting CO2 into value-added chemical products through chemical processes can realize the resource utilization of CO2 and reduce the greenhouse effect at the same time.Among them,the preparation of cyclic carbonate by the combination of epoxides and CO2 is an atom-economical reaction,and almost no by-products are produced during the reaction.Cyclic carbonates are widely used in industry and are in great demand.Although homogeneous catalysts can show good catalytic performance for this reaction,the problems of separation and recycling of homogeneous catalysts make it difficult to apply them on a large scale.Therefore,it is very necessary to design heterogeneous catalysts with high catalytic performance.The main research contents and conclusions of the paper are as follows:1.From the perspective of efficient activation of reactants,a bifunctional poly(ionic liquid)catalyst containing both CO2 adsorption and CO2 activation groups was designed and synthesized,wherein the triazine group was a CO2 adsorption and activation group.It can be seen from the characterization that this bifunctional catalyst has higher CO2 adsorption capacity and stronger CO2 interaction than the monofunctional catalyst.Moreover,the evaluation results of the catalytic activity show that the bifunctional poly(ionic liquid)exhibits very excellent catalytic performance.Under the same catalytic conditions,the yield of the bifunctional poly(ionic liquid)as a catalyst can reach three times that of the monofunctional poly(ionic liquid)catalyst.For different reaction substrates,there are obvious yield improvements,indicating that this catalyst has good substrate applicability.2.In order to solve the problem that high temperature and high pressure reaction conditions are required for the reaction of CO2 with epoxides,a series of catalysts are designed for catalytic conversion induced by light.Among them,catalysts with an electron donor-acceptor structure have better conversion rates under illumination,while catalysts that do not satisfy this electronic structure have basically the same conversion rates under illumination and heating at the same temperature.The best screened catalyst showed high catalytic activity under light,and the conversion of the epoxy substrate can reach 4.9 times that of the epoxides when heated in the dark at the same temperature,and was much better than the performance of the tested homogeneous catalysts.The mechanism of CO2 cycloaddition reaction under illumination was deeply explored by photocurrent response tests,quenching experiments,Mott-Schottky tests and electron spin resonance tests. |
