Synthesis And Catalytic Application Of Multifunctionalized Hierarchical UiO-66 Gels And Its Derivatives Carbon

Currently,more than 95%of chemical products are produced by catalytic processes,which makes the preparation of efficient catalytic materials a hot research area.Heterogeneous catalysts are widely used in the fields of chemical industry and environmental protection,and their main preparation method is to disperse catalytically active sites on high-surface-area support materials.Metal-organic frameworks（MOFs）are widely used as supports for active sites of heterogeneous catalysts due to their high specific surface area,diverse structures,and tunable porosity.However,in the field of heterogeneous catalysis,MOFs are limited by their inherent microporous structure,single and unstable active sites,and difficulty in recycling most of them in powder form,which hinder their wide application.Therefore,it is of great significance to design a MOFs-based catalyst with hierarchical porous structure,multifunctionality,active site stabilization and shaping.In this paper,multifunctional hierarchically porous MOFs gels and their derived carbon materials were designed and used to anchor active sites,and hierarchically porous MOFs gel composites and MNPs@MOFs-derived carbon materials were prepared,which are suitable for mass transport and large-scale substrates.A series of research results have been achieved in the heterogeneous catalysis involved.The specific research contents are as follows:（1）To solve the problem of microporous structure and powder state:We constructed hierarchically porous Ui O-66 using a defect-inducing strategy,and functionalized the hierarchically porous Ui O-66 with IL（1-aminoethyl-3-methylimidazolium bromide）.Ui O-66 was then compounded with agarose to form a multifunctional hierarchical porous H-IL@Ui O-66 gel.Its hierarchical porous structure is beneficial to facilitate the mass transport of catalytic substrates and products,and the acid-base properties of IL and the exposed Lewis acid sites of metal Zr node defects are beneficial for anchoring and activating epoxide and CO₂ molecules.The functionalized graded H-IL@Ui O-66 gel was applied to the cycloaddition reaction of CO₂ and styrene oxide,showing a catalytic performance with a conversion of>99%,showing removal of>98%of adsorption the organic dye Rhodamine B,and showing excellent selective screening effect on the catalysis and adsorption of substrate macromolecules.Furthermore,the functionalized hierarchically H-IL@Ui O-66 gel can be easily isolated from the system and reused three times without sacrificing its catalytic activity.More importantly,the functionalized hierarchically porous H-IL@Ui O-66 gel also showed excellent catalytic performance for the catalytic conversion of CO₂ and epoxides with different substituents.（2）In order to solve the problem of single and unstable active sites and microporous structure:we used a defect-inducing strategy to construct a hierarchically porous H-Ui O-66-NH₂,and prepared hierarchical nano-sized（～20 nm）H-Ui O-66-NH2 by carbonization.H-Zr O₂/NC carbon.Hierarchical nano-H-Zr O₂/NCs inherit the microporous/mesoporous structure and diverse chemical compositions to serve as carriers for active-site Pd NPs.XPS characterization and density functional theory（DFT）calculations show that N-doped sites of carbon composites and oxygen vacancies of Zr O₂ can effectively stabilize and activate Pd NPs through strong host-guest interactions,resulting in the formation of highly dispersed and ultra-highly dispersed Pd NPs.The fine Pd NPs（～1.5 nm）,the modification of N atoms and the integrated Zr O₂ greatly enhance the hydrophilicity of Pd@H-Zr O₂/NC.When the functionalized and graded Pd@H-Zr O₂/NC composite was applied to the hydrogenation reaction of furfural in the aqueous phase,it showed good catalytic performance with a conversion rate and selectivity of>99%.In addition,the graded Pd@H-Zr O₂/NC also exhibited excellent catalytic performance for the hydrogenation of a series of unsaturated hydrocarbons in an aqueous system,and the catalytic activity and structural stability were maintained after 5 consecutive cycles.