Study On The Synthesis Of MOFs Based On 4,4’,4’’-nitrilotribenzoic Acid And Its Adsorption And Catalytic Properties

With the development of science and technology in modern society and the progress of civilization,people pay more and more attention to environmental problems,especially to solve the pollution of fresh water resources caused by industrial wastewater and the greenhouse effect and other environmental problems caused by CO₂and other waste gas emissions.Therefore,it is of great significance to design materials that not only can absorb pollutants in wastewater but also capture and transform CO₂in the atmosphere.Metal-organic Frameworks（MOFs）is an organic-inorganic hybrid material with intramolecular pores formed by the self-assembly of Organic ligands and Metal ions or clusters through coordination bonds.Due to its large surface area,high porosity,rich active sites and many other characteristics,it is widely used in many fields of research.This thesis explored the potential applications of MOFs in adsorption separation and catalysis.In this thesis,The triangulated carboxylate ligands,4,4’,4’’-nitrilotribenzoic acid and two pairs of imidazoles auxiliary ligands（1,4-bis（imidazole-1-methylene）benzene and 1,2-bis（imidazole-1-methylene）benzene）and pyridines auxiliary ligands（2,2’-bipyridine and 4,4’-bipyridine）which are isomers of each other were selected to use the mixed-linker strategy with transition metal ions of Zn²⁺,Cd²⁺,and Co²⁺under solvothermal conditions.Nine MOFs materials have been synthesized and they are[Zn₄O（ntba）₂]_n（1）,[Cd₃（ntba）₂（H₂O）]_n（2）,[Cd₃（ntba）₂（1,4-Bis）（H₂O）₂]_n（3）,[Cd₃（ntba）₂（2,2’-bipy）₂]_n（4）,[Cd₃（ntba）₂（1,2-Bis）₂]_n（5）,{[Cd₂（ntba）（1,2-Bis）（NO₃）]（DMA）}_n（6）,[Zn₃（ntba）₂（4,4’-bipy）]_n（7）,{[Co（Hntba）（1,4-Bis）]（DMF）（H₂O）_0.5}_n（8）and[Co₃（ntba）₂（2,2’-bipy）₂]_n（9）.The nine materials’structure was determined by CCD single-crystal diffraction,and their successful preparation and thermal stability have also been verified by PXRD,IR,and TG characterization.The determination of the specific surface area and single-component gas adsorption-desorption for each material demonstrated their porous nature and good CO₂adsorption properties.According to the ideal adsorbed solution theory（IAST）,the theoretical separation ratios of the binary mixed components as CO₂/CH₄（50/50）,CO₂/N₂（50/50）and CO₂/O₂（50/50）were calculated for MOF 1,MOF 4 and MOF 9 because their large surface area and outstanding CO₂adsorption performance.The results showed that MOF 1 and MOF 4 have good CO₂adsorption and separation ability.The methylene blue（MB）degradation experiments have been carried out among MOF 1,MOF 6 and MOF 7 with good stability and regular surface area and pore size.The results showed that MOF 1 had excellent adsorption capacity.In addition,the catalytic performance of carbon dioxide and epoxide addition on MOF 1,MOF 2,MOF 4,MOF 5,MOF 6,MOF 8 and MOF 9 was studied under atmospheric pressure and solvent-free conditions by optimizing the temperature,reaction time and amount of catalysts.Under the optimal reaction conditions,the universality of the catalysts to the substrate and the cyclic stability were tested.The experimental results show that MOF 2,MOF 4,MOF 8 and MOF 9 as catalysts for the reaction of CO₂and epoxide have the advantages of high catalytic rate,strong universality,high stability and good sustainability,and also confirm the feasibility of these seven MOFs as good catalysts for the reaction of CO₂ and epoxide.