Design And Synthesis Of Multi-functional POMs @ Zr-MOF By The Method Of Bottle-around-ship And Catalytic Performances

The metal-organic framework is a new type of multifunctional composite material with special properties.Because of its special pore structure and high specific surface area,it is different from traditional zeolite,activated carbon and other porous materials,and has considerable potential applications in the field of catalysis.The purpose of this paper is to explore the application value of metal-organic framework as a catalyst carrier,develop a new heterogeneous catalyst of phosphotungsten solid acid,and use the Bottle-around-ship method to prepare POMs@UIO-66 composite materials to improve phosphotungsten heteropoly acid The dispersion degree of the active component and enhance the interaction between it and the carrier;use the esterification reaction as a probe reaction to detect the catalyst activity,discuss the influence of the reaction conditions on its catalytic performance;and through the POMs@UIO-66 composite material Carry out various characterizations to further correlate the relationship between the catalytic activity of the catalyst and the structure of the catalyst itself.In this experiment,POMs@UIO-66 composite catalysts with different phosphotungstic acid loadings were prepared by the Bottle-around-ship method,and POMs@UIO-66 was composited by inductively coupled plasma atomic emission spectrometry（ICP-AES）The content of phosphotungstic acid in the material was determined,and its structure and morphology were characterized using XRD,FT-IR,TEM,N₂adsorption and TG.It was found that when the loading of phosphotungstic acid was 8 mg,the utilization rate of phosphotungstic acid was the highest,and the main body of the composite material UIO-66 maintained its original shape.First,the esterification reaction of oleic acid and methanol was used to investigate the catalytic performance of POMs@UIO-66,and the best reaction conditions were obtained:the ratio of alcohol to oil was 15:1,the amount of catalyst was 5%m（oleic acid）,and the reaction time was At 8 h,when the reaction temperature is 75℃,the highest conversion rate of oleic acid can reach 91%.The catalyst reusability study shows that the stability of the POMs@UIO-66 catalyst is better.The catalyst can be used continuously for at least 5times,and the conversion rate of oleic acid can still reach 87%after five times of use.Then we investigated the effect of POMs@UIO-66 on the esterification reaction of other higher fatty acids with methanol,including capric acid,lauric acid and palmitic acid,and found that the catalytic yield can reach about 90%,which is the same as oleic acid and methanol.The catalytic yield of the esterification reaction is similar,indicating that POMs@UIO-66has higher catalytic activity for the esterification reaction of higher fatty acids with methanol.Then,the esterification reaction of acetic acid and n-octanol was used to investigate the catalytic performance of POMs@UIO-66,and the best reaction conditions were obtained:the ratio of acid-alcohol substance is 2:1,the amount of catalyst is 5%m（acetic acid）,and the reaction time At 12 h,when the reaction temperature is 100℃,the highest conversion of acetic acid can reach 63%.The catalyst reusability study shows that the stability of the POMs@UIO-66 catalyst is good.The catalyst can be used continuously for at least 5 times.After the fifth use,the conversion rate of acetic acid still reaches 60%.Then the influence of POMs@UIO-66 on the esterification reaction of other lower polyols with acetic acid was investigated,including ethanol,n-propanol and n-butanol,and the catalytic yield was found to be about 60%,and the ester of higher fatty acid and methanol From the comparison of the results of the chemical reaction,it was found that POMs@UIO-66 showed higher catalytic activity.