Surface Modification And Rapid Synthesis Composite Of MOF-74（Ni） And Its Adsorption Toward Alkane,Alkene Nd CO₂

The international community is facing serious energy crisis, one of the most effective measures to solve this problem is energy conservation. Under the background of huge industry demand for Alkane Alkene separation and CO₂ adsorption separation, this research focused on surface modifiaciton and rapid synthesis composites of MOF-74（Ni）. Their adsorption performance of Alkane, Alkene and CO₂ was measured, and their adsorption mechanism was disscussed. This study has value of theoretical research and practical significance.MOF-74（Ni） was synthesized by solvothermal synthesis method. The adsorption performance and adsorption mechanism of propylene and propane were researched. C₃H₆ was preferential adsorbed because of the π-complexation between C₃H₆ and MOF-74（Ni） unsaturated metal sites. MOF-74（Ni） is one of the materials which have the largest C₃H₆ adsorption capacity, its C₃H₆ adsorption capacity is up to 7.4 mmol/g at 298 K. IAST theory calculation results showed that the adsorption selectivity of C₃H₆/C₃H₈ increased with temperature rising. The ISAT selectivity of C₃H₆/C₃H₈ on MOF-74（Ni） is up to 12 at 328 K. The desorption activation energy of C₃H₆ and C₃H₈ on MOF-74（Ni） are 68.92 kJ/mol and 50.80 kJ/mol respectively.MOF-74（Ni） was modified with Silane Coupling for improving its Moisture resistance. The results of TG analysis, water vapor and CO₂ isotherms indicated that the modified MOF-74（Ni） exhibited very good thermal stability as MOF-74（Ni）, and its adsorption of water vapor was weakened. After vacuumed at general temperature, the regeneration performance of CO₂ adsorption on modified MOF-74（Ni） is double that of original MOF-74（Ni）.Composites GrO@MOF-74（Ni） were synthesized by solvothermal synthesis method. With the GrO quality increasing, some mesopores formed, BET surface areas of composites can be up to 1322m²/g. SEM images indicated that GrO had an influence on MOF-74（Ni） crystals, the burr morphology formed and crystals became small. A large amount of GrO didn’t attach to MOF-74（Ni） crystals, which was contributed to GrO gravity settlement. The isotherms of carbon dioxide, Alkane and alkene on GrO@MOF-74（Ni） became steeper, indicated GrO complex further reinforced the adsorption force of composite toward target molecule, which was beneficial to improving adsorption selectivity.A method for rapid synthesis of GO@MOF-74（Ni） composite was proposed, GO@MOF-74（Ni） was successfully synthesized in 1 hour. The BET surface areas of the GO composites are between 1250 and 1320 m²/g. SEM images indicated composites had stratiform morphology. Compared to orginal MOF-74（Ni）, the adsorption capacity and adsorption selectivity of CO₂/N₂、C₂H₄/C₂H₆ and C₃H₆/C₃H₈ on composites were enhanced. Compared to MOF-74（Ni）, the selectivity of C₃H₆/C₃H₈ on 1GrO@MOF-74（Ni） was up to 17 at 298 K, increasing the IAST selectivity by 58.5%.