Design,Synthesis And Catalytic Performance Of Porous Materials Based On Covalent Organic Frameworks

Covalent organic frameworks,as a new type of organic crystalline porous material,has unique structure properties,which has important application prospect in gas adsorption-separation,proton conduction,photoelectric,catalysis and other fields,and has attracted much attention from domestic and foreign scholars.In this paper,different types of functionalized COF materials were designed and prepared,and their structure and catalytic properties have been studied and discussed.Firstly,the H₂P-DHPh COF containing hydroxyl groups in the framework was selected as the precursor,and the imidazole cationic COF material,BMIMBr@H₂P-DHPh COF,was obtained by post-modification modification.The changes of COF materials before and after modification were characterized by FT-IR,PXRD,TG and N₂ adsorption-desorption techniques.The prepared BMIMBr@H₂P-DHPh COF was used as a catalyst to catalyze the cycloaddition reaction of the C02-epoxides to test its catalytic performance.The results show that the COF catalyst has good catalytic performance for both propylene oxide and epichlorohydrin under specific reaction conditions,and the yield of the products is higher than 90%.Secondly,the Me-Im COF containing imidazolyl group in the framework was selected as the precursor,and treated with alkali after ionization,and finally N-heterocyclic carbene type COF material,Me-Im NHC COF,was obtained.Similarly,the materials were characterized by FT-IR,PXRD,TG and other analytical techniques.The prepared Me-Im NHC COF was used to catalyze the transesterification reaction of glycerol and linear dimethyl?meth?carbonate to synthesize glycerol carbonate.Experiments show that the catalyst has a good catalytic effect,the product yield of about 95%.However,the structural properties of Me-Im NHC COF need to be further explored and studied.Finally,the TF-Py COF with a stable framework was modified by 1,3-propane sulfonate,and then reacted with cobalt acetate to obtain[SO3Co]-TF-Py COF.The materials were characterized by FT-IR,PXRD,ICP-OES,XPS,TG and other analytical techniques.For the first time,the load of metal in COF was realized by the electrostatic interaction between ions.The prepared[SO3Co]-TF-Py COF was used as the catalyst,the cycloaddition reaction of the CO₂-epoxides was selected and used to test its catalytic performance.The results show that the COF catalyst has the universality for different substrate molecules under specific conditions,and the yield of the product is higher than 95%.