Design,Synthesis,Gases/Dyes Adsorptive Separation And CO₂ Catalytic Conversion Investigations Of Porous Functionalized MOF Materials

Metal-Organic Frameworks(MOFs)are a new class of organic-inorganic hybrid porous crystalline materials.Compared with traditional inorganic porous materials,due to the advantages of diverse structures,large specific surface area and pore volume,and easy targeted control of structure and porosity,this type of porous material has show great application potential gas adsorption/separation and heterogeneous catalysis.At present,fossil fuels such as oil,natural gas,and coal still dominate the world's total energy consumption(more than 80%).When these fuels are consumed,they inevitably emit a large amount of carbon dioxide,which is main reason considered to cause global warming.At the same time,in chemical production,carbon dioxide is also an important source of C1.Therefore,the development of a new type of MOF material with high CO2 adsorption,storage,separation and catalytic conversion has very important theoretical and practical significance.In this paper,four polydentate carboxylic acid ligands H3 TCPBT,H6DBATC,H4 APDP and H2 ABP modified with different functional groups were designed and synthesized,and based on the principles of crystal engineering,the above ligands were combined with paddlewheel-like [Cu2(COO)4] SBU by self-assembly has resulted in four novel functional group-modified porous MOF materials: HNUST-10,11,12,and 13,have been studied in detail the structure of the four MOF materials,CO2 gas storage separation(dye adsorption separation)and CO2 gas catalysis conversion performance and other aspects.The results show that:(1)The skeleton of HNUST-10 collapses after activation,but it has a larger porosity,and the skeleton structure is stable in organic solvents such as DMF.The material exhibits high selectivity and high adsorption/separation ability for methine blue in DMF solution;(2)The framework structure of HNUST-11 remains stable after activation.The material exhibits high CO2 adsorption capacity under low pressure and high pressure conditions,and it has better CO2 adsorption capacity at room temperature.High CO2/N2,CO2/CH4 gas adsorption selectivity of the same type of rht-MOF.Through break-through experiments,it has been proved that HNUST-11 has good CO2/N2,CO2/CH4 gas selective separation ability.In addition,this thesis explored the CO2 catalytic conversion performance of HNUST-11,and used density functional theory to study its reaction mechanism;(3)HNUST-12 reduced the size of the ligand on the basis of HNUST-11,and introduced pyridine nitrogen and amino groups at the same time.Modified pores have more catalytic active centers than HNUST-11,so it exhibits a better catalytic conversion rate per molar mass in the cycloaddition reaction of CO2 and epoxy compounds(for epibromohydrin,The TON value is as high as 3429.8);(4)HNUST-13 is an example of an ultra-microporous MOF material with both amino and bromo group modification,and also has a copper paddle wheel SBU saturated with N atom coordination,which is expected to exhibit excellent performance in CO2 gas adsorption separation and catalytic conversion.In summary,the introduction of modified functional groups such as amino and amide into the framework structure of porous MOFs is expected to keep the material's high specific surface area and large pore volume,while also effectively increasing the material's selective adsorption performance of CO2.In addition,the unsaturated Cu(II)coordination sites and modified functional groups in the material frame structure can provide multiple catalytic active centers for catalyzing the cycloaddition reaction of CO2 and epoxy compounds,effectively improving the catalytic performance.The results obtained in this thesis not only have a certain reference significance for the synthesis of polar functional group modified porous metal organic framework compounds,but also provide a certain experimental reference for the adsorption and separation of CO2 mixed gas and catalytic conversion.