The MOFs@POPs Hybrid Materials As Catalyst For High Efficiency CO₂ Conversion To Cyclic Carbonate

As an important factor of global warming,reducing the concentration of carbon dioxide in the atmosphere is very important to the climate.At the same time,carbon dioxide can also be used as an important C1 raw material,which can be converted into high value-added products to reduce the impact on the environment and have good economic benefits.Therefore,more and more attention has been paid to the cyclic carbonate formation by the cycloaddition of carbon dioxide with epoxides.MOFs have high specific surface area and abundant Lewis acid sites,and POPs have large surface area and adjustable pore size.MOFs@POPs materials can effectively combine the advantages of MOFs and POPs.Herein,two types of MOFs@POPs?ZIF-8@TU-POP and ZIF-67@POP-n?hybrid materials were designed to catalyze the cycloaddition reaction of CO₂ with epoxides.First,ZIF-8@TU-POP hybrid material was synthesized.Because of the abundant Lewis acid sites(Zn²⁺)and hydrogen bond donors?urea groups?,it can be selected as an ideal catalyst for the cycloaddition reaction of CO₂ with epoxides.Firstly,the synthesized ZIF-8@TU-POP hybrid material was characterized by PXRD,FT-IR,SEM,XPS,TG and other means,indicating that the hybrid material was successfully fabricated.Subsequently,ZIF-8@TU-POP showed excellent catalytic performance in catalyzing the cycloaddition reaction of CO₂ with propylene oxide,with a conversion rate of 98%and a selectivity of 99%.The substrate applicability was also explored,and it was found to have excellent catalytic effect on other epoxides.Meanwhile,the catalyst has good recyclability and stability.After six runs,the conversion can reach 96%.A MOFs@POPs hybrid material ZIF-67@POP-n was synthesized and characterized by PXRD,FT-IR,SEM,XPS,TG and other means,which indicated that the hybrid material was successfully fabricated.Because of the rich Lewis acid sites and the large number of nucleophilic groups,this hybrid material was considered for catalyzing the cycloaddition reaction of CO₂ with epoxides.Subsequent catalytic experiments showed that the catalyst had a good catalytic performance for the cycloaddition reaction of CO₂ with epoxides.When the epoxide was propylene oxide,the conversion of propylene oxide could reach 93%,and its good substrate applicability was found through catalytic experiments.After five cycle experiments,ZIF-67@POP-n did not change significantly.The good cyclicity and stability of ZIF-67@POP-n are illustrated.Two kinds of MOFs@POPs hybrid materials provide research ideas and technical support for our research on CO₂ capture and transformation.