The Preparation Of Metal Phosphonates And Their Catalytic Performances In CO₂ Conversion

CO₂ is the greenhouse gas that contributes the most to global warming.At the same time,as the most abundant C1 resource in nature,CO₂ is safe,cheap and renewable.The conversion of CO₂ into cyclic carbonates with high added value has important social significance for both environmental improvement and resource utilization.However,traditional catalysts usually use catalysts with low catalytic activity and harsh reaction conditions,such as high temperature and high pressure.In order to reduce the cost input and energy consumption in the industrial production process,it is necessary to achieve efficient catalysis under mild reaction conditions.In this study,the catalytic conversion of CO₂ was initially explored.First,zoledronic acid was selected as the linker,and cobalt nitrate and cadmium acetate were used as metal salts to synthesize two kinds of microporous compounds 1 and 2 by hydrothermal method.Its structure and composition were characterized in detail by XRD、PXRD、FTIR、TG、XPS and SEM.At the same time,the catalytic performance of compound 1 was investigated,and the catalytic activity of reaction temperature,time and catalyst loading on the cycloaddition reaction of CO₂and styrene oxide was discussed.It is confirmed that the conversion of 97.2%can be achieved under normal pressure,reaction conditions of 100℃,24 h,catalyst load of 0.5%and TBAB of0.3%.Moreover,the catalyst can be recycled for 8 times without obvious reduction in catalytic efficiency and remains stable.At the same time,it also shows good catalytic activity for various epoxides,that is,it exhibits good catalytic universality.Subsequently,mixed metal phosphonate STA-12（Fe Co Mn）was synthesized by using ferrous chloride,cobalt nitrate and manganese acetate as mixed metal sources and 1,4-piperazinediylbis（methylene）phosphonic acid as organic ligand through reference.It was confirmed by PXRD,FTIR and EDX that the compound was successfully prepared and indeed doped with three metals.The compound was used for catalytic reaction.The effects of different reaction time,temperature and type of cocatalyst on the cycloaddition reaction were investigated using epoxy substrate butyl glycidyl ether with the larger size as a model.It was found that under atmospheric pressure,when the reaction parameters were 100℃,12 h,the cocatalyst TBAB loaded 0.3%and the catalyst 50 mg,the conversion could reach 98.4%,and catalytic effect was more significant than that of compound 1.In addition,the catalyst can also be recycled for 5 times and has good universality.