Synthesis And Application Of Metal-organic Frameworks Derived Materials

Metal-organic frameworks(MOFs)are a class of porous materials with periodic structure formed from metal ions or clusters with organic ligands via self-assembly.MOFs have lots of advantages,such as varied composition,high specific surface area,uniform pore channel and ease in modification,making them have broad application in catalysis,medicine,storage and separation of gas,energy,sensing and other fields.As an extension of MOFs,MOFs derived materials(including pyrolysis products of MOFs,MOFs composite materials,etc.)can inherit the advantages of MOFs,and also bring new properties,which expands the application of MOFs materials and optimizes their performance.Therefore,the preparation of MOFs derived materials has become one of the effective methods of new materials.How to design and prepare MOFs derived materials with improved properties becomes a hot topic in recent years.The object of this dissertation is to prepare MOFs derived materials via pyrolysis and reduction,combination with metal nanoparticles,drug and inorganic mineral.And these derived materials were tested in the conversion of glycerol,degradation of organic wastewater,hydroxylation of phenol and drug delivery to explore the relationship between the structure and the performance of MOFs derived materials.The main works of this dissertation contents:First,this thesis showed that metal/metal oxides and alloy catalysts were synthesized via controlled calcination and reduction using bimetallic MOFs as precursors,which were applied in the gas phase hydrogenolysis of glycerol.Compared with catalysts prepared via traditional methods,catalysts prepared with MOFs as precursors exhibited better catalytic performance.It was found that Co/ZnO-ZIF catalyst from CoZn-ZIF precursors had the structure with high dispersed Co nanoparticles on the surface of ZnO sheets.This structure was contributed to contacting glycerol and H₂ with Co nanoparticles,accelerating the hydrogenolysis of glycerol to ethanol.The space time yield of ethanol could reach 1.45 g/g_cat./h at210? and 2 MPa,and ethanol was formed mainly via the continuous hydrogenation of glycerol(1,2-propanediol as intermediate).Furthermore,the rice granular CoFe alloy catalyst(CoFe-ZIF-R)with a uniform size was obtained via the calcination and reduction of CoFe-ZIF.Co in CoFe alloy was conducive to the activation of hydrogen,and Fe could enhance the acidity of catalysts.It was found that the formation of allyl alcohol was mainly via dehydration and hydrogenation under the synergistic effect of activated hydrogen and acid sites.The yield of allyl alcohol reached 61.6%and the space time yield was 1.02 g/g_cat./h at 250?,2 MPa and WHSV=2.6h^-1.Besides,CoFe-ZIF-R also exhibited good stability.In order to solve the easy agglomeration of metal particles in the pyrolysis of MOFs,a series of Fe N_x@g-C₃N₄-4-T catalysts were obtained via the pyrolysis of Fe-trimesic acid complex(Fe-BTC)and melamine,which were used in the heterogeneous fenton oxidation of rhodamine B(RhB).It was found that the catalyst pyrolyzed at 400 ?(Fe N_x@g-C₃N₄-4-400)was the composition of g-C₃N₄,high dispersed Fe(?)-N_x and residual Fe-BTC.The coating of g-C₃N₄ and the coordination of nitrogen improve the stability of catalyst.Fe(?)-N_x could effectively decompose H₂O₂ to produce·OH,and Fe-BTC could accelerate the spread of·OH to reduce the generation of·OOH from·OH and H₂O₂,which made it exhibit a high activity for fenton oxidation of RHB in full pH range.And Fe N_x@g-C₃N₄-4-400 was also suitable for degrading other organic matters.In addition to being precursors,MOFs could also be used as supports.Utilizing the coordination effect and the confined effect of pore channels in MOFs,Cu@UiO-bpy with high dispersed metallic Cu was prepared and applied in the hydroxylation of phenol.It was found that the high dispersed Cu could provide abundant active sites,and the large specific surface area of Cu@UiO-bpy was conducive to the contact between reactants and active sites.Meanwhile,the encapsulation of UiO-bpy could inhibit the agglomeration and the loss of Cu.When the molar ratio of H₂O₂/phenol was 5 and reacting for 60 min at 70?,the conversion of phenol reached 70.5%and the yield of dihydroxybenzene was 47.3%.Aiming to the problems of low bioavailability and easy mucosal injury in oral drug delivery,a drug delivery platform(drug@M-ZIF-8)with drug-loaded ZIF-8 as the core and montmorillonite(MMT)as the shell was synthesized via a one-pot method.The experimental results showed that the structural adaptability and the high porosity of ZIF-8 enabled the effective embedding of various drugs.The coating of MMT enhanced the stability of ZIF-8,realized the controlled release of drugs in acidic environment,and improved the biocompatibility.In the model of gastritis and colitis,M-ZIF-8 not only achieved the efficient delivery of drugs in the gastrointestinal tract,but also promoted the healing of gastrointestinal mucosa with Zn and MMT,greatly improving the therapeutic effect.In conclusion,the preparation and application of MOFs derived materials were preliminarily explored,and the relationship between their structure and properties was studied in this dissertation.We hoped that our research could provide references for expanding the application of MOFs derived materials.