Preparation Of Co-MOF-74 And Computational Study Of CO₂ Adsorption And Separation

Metal-Organic framework(MOF) material is a kind of porous mesh structure materials formed by metal ions and organic ligands. They have a wide range of application prospect in gas storage, separation and catalysis, etc, with their adjustable pore size, large surface area, controllable property and high thermal stability. But more than tens of thousands MOFs have been pulished yet, it will cost too much time and labour to study MOFs by traditional experiment method.The purpose of this thesis is to study the best synthesis process of Co-MOF-74.The molecular simulation method will be introduced into the prediction of the Co-MOF-74 modified material’s performance, and the data will be able to guide Co-MOF-74’s modification direction.Solvent-thermal synthesis method is used in this thesis to synthesize the Metal-Organic Framework Co-MOF-74. The effects of solvent-thermal time,temperature, solvent composition, solute ratio and vacuum drying temperature on the synthesis of Co-MOF-74 are investigated. The Co-MOF-74 was characterized by the test of powder X-ray diffraction(XRD), scanning tunneling microscope(SEM), thermal gravity analysis(TG) and other testing methods. The experimental results show that the best synthesis process is Co(NO3)2·6H2O and DHTA’s Moore ratio of 3:1, 100 ℃ solvent-thermal temperature, 24 h solventthermal time, 100℃ vacuum drying temperature for 5h and average volume of DMF/ethanol/water al solvent. Co-MOF-74 with complete structure, high crystallinity and better morphology can be synthesized on these conditions.In this thesis, the optimized structure of Co-MOF-74 was simulated by Material Studios. The optimized crystal cell parameters were found close to the experimental parameters by XRD, with an error around 1%. This is the provement of the computing simulation method’s accuracy. The atomic charge of Co-MOF-74 and its modified structure were calculated by Gaussian, and the modified group was found to have impact on the distribution of electron cloud of benzene ring in a certain degree.The CO2 single-component and CO2/N2 bi-component adsorption ability of Co-MOF-74 and its modified structure were calculated by Sorption. The further accuracy of this series of calculation method has been proved by the good matchbetween simulation results and the results reported in literatures. And the proved method was applied on the simulation of gas adsorption performance of-F and-CH3 modified Co-MOF-74. Simulation results show that the-CH3 modified CoMOF-74 own a better CO2 one-component gas adsorption ability on low pressure;and the-F modified Co-MOF-74 has a better CO2/N2 bi-component gas separation ability.