Design And Synthesis Of Metal-organic Framework Constructed By Four Carboxylic Acids Organic Ligands With Gas Storage And Separation Properties

Metal-organic frame material（MOFs）is a new type of organic-inorganic hybrid crystalline materials which has been developed in the last few decades.This new type of porous materials can be readily self-assembled from their corresponding metal ions or metal containing clusters with suitable organic linkers,the diversity of metal ions and organic linkers makes MOFs with highly designability.The introduction of special functions on organic ligands make MOFs exhibit different properties.So MOFs materials have a broad application prospect in various fields.In this paper,we have realized the storage and separation of various gases for MOFs materials through reasonable experimental design,and provides a reference for further improving the performance of MOFs materials.In this paper,a metal-organic framework Co₃ABTC was synthesized by solvothermal reaction of 3,3’,5,5’azobenzene tetra carboxylic acid ligand with cobalt nitrate.The crystal system of the material is cubic crystal system.Three cobalt atoms form secondary building unit,the secondary building unit and organic ligands are connected by the carboxylic acid to form a three-dimensional porous structure.After the activation of Co₃ABTC,the separation of C₂H₂ and CO₂ gas shows good performance.Specially,the Henry law selectivity for CO₂-C₂H₂ is 2.99 at 273 K.The IAST selectivity at 1 kPa is 26.3 for CO₂-C₂H₂ While the temperature reaches 298 K,the Henry law selectivity for CO₂-C₂H₂ is 4.24.And the IAST selectivity at 1 kPa is3.4.In order to further improve the performance of gas adsorption and selective separation,experimental use of the H₄CDDS organic ligand and copper by solvothermal reaction,and get metal-organic framework material[Cu₂（L）（H₂O）₂]?（DMF）₈（H₂O）₄（ZJU-12）with three different pore structures.The double paddle wheel secondary building unit and organic ligands are connected by the carboxylic acid to form a three-dimensional porous structure.There are three different types of pores along the c axis,the sizes are 3×7.5?,6.8×6.8?and 2.5×6.5?.At 273 K,the experimental results show that the Henry law selectivity for C₂H₂-CH₄,CO₂-CH₄ and C₂H₂-CO₂ are 27.97,6.3 and 4.43.At 1 kPa,the IAST selectivity for equimolar amount of gases are 36.3,3.7 and 6.5.The Henry law selectivity are 18.03,3.76 and4.78 at 298 K,and the IAST selectivity at 1 kPa are 21.4,4.7 and 3.8.