Construction Of MOF-based Heterogeneous Catalysts And Their Catalytic Oxidation Reaction

Due to the porous structure,large specific surface area,and modifiability,metal-organic frameworks（MOFs）have shown remarkable application prospects in the catalytic field.In recent years,the development of MOFs-based composite materials and MOFs-derived hybrid materials have further broaden the application field of MOFs materials.This paper firstly researched the design,synthesis and catalytic cascade reaction of MOFs-based bi-functional composites.Herein,MOFs mainly be applied as supports and/or provide Lewis acid/base sites;Subsequently,for the first time,we designed and constructed a new isomerous MOF1@MOF2 composite,BMZIF@HKUST-1,and investigated catalytic epoxidation of styrene by its derivative.The research results of this paper are as follows:1.Compared with multi-step and batched synthesis of organic intermediate,the one-pot multi-step cascade reaction has great advantages,not only avoiding complex operation processes,but reducing energy consumption and resources waste,and also reducing a large quantity of solvents.MOFs-based composites could combine the respective active sites of both MOFs and guest molecule,which provides more possibility for design and synthesis of multifunctional MOF-based catalysts.In this work,we synthesized a bi-functional MOF-based catalyst,Cd S/MOFs,which combined the photocatalytic oxidation site of Cd S with the Lewis acid/base site of MOFs.The hybrid realized the catalytic research toward one-pot cascade reaction,and also had good activity for the photodegradation of dyes.MOFs not only provide catalytic active sites,but disperse and stabilize Cd S particles.In addition,photosensitive NH₂-MIL-125 and Cd S can form a heterojunction,which inhibits photoelectron-hole recombination rate,and then improves photocatalytic activity.2.In a second work of this paper,isomerous BMZIF@HKUST-1 composite with core-shell structure was successfully synthesized for the first time.At present,the research of core-shell MOF1@MOF2 materials is still in the preliminary stage with few relevant achievements.The successful synthesis of BMZIF@HKUST-1 in this paper can provide new ideas and instructions for the subsequent synthesis of more other isomerous MOF@MOF structures.In addition,we also investigated the catalytic application of BMZIF@HKUST-1 derived metal/carbon materials via pyrolysis under H₂/Ar atmosphere using a temperature programmed method.The Co-C@Cu-C material with higher stability was obtained.To improve selectivity,we exchange Ag with Cu through a simple and controllable ion-exchange method to obtain Co-C@Cu Ag-C.The catalytic epoxidation of styrene was selected as a model reaction,finding that the activity and selectivity of Co-C@Cu Ag-C has been largely improved.