Synthesis And Characterization Of Novel Carboxylic Ligand Metal Organic Framework

Coordination framework materials have exceptional high adsorption uptakes when applying in hydrogen storage, but the adsorption is mainly physical adsorption and high uptake only happens when tested in cryogenic equipment. In order to solve this problem, one of available solutions is to synthesize coordination framework materials with high enthalpy for H2 adsorption.The pore size distribution and the enthalpy for H2 adsorption of coordination framework materials could be tuned by design of the structure of carboxylic acid ligand. A novel carboxylic acid ligand 1,3,5-tris(3′,5′-dicarboxyl-phenyl)benzene was synthesized via Suzuki coupling of Benzene-1,3-dicarboxy-ethylester-5-boronic acid and 1,3,5-Tribromobenzene using Pd(PPh3)4 as catalyst.Benzene-1, 3-dicarboxy-ethylester-5-boronic acid was prepared by the etherification of 3, 5-dicarboxyphenylboronic acid, which is the product of oxidizing 3, 5-dimethylphenylboronic by KMnO4. The structures of products combined the merits of ligands used in synthesizing MOF-177 and NOTT-112 respectively.The structures of products synthesized were identified by IR and 1H NMR. The spectra of IR and 1H NMR confirmed with the chemical structures of the products. Based on the new ligand synthesized, a novel metal organic framework was synthesized through solvothermal synthesis reaction with 1,3,5-tris(3′,5′-dicarboxyl-phenyl)benzene and Cu(NO3)2? (3H2O) as reactant. The thermal stability, crystal structure, BET surface of the novel coordination framework material was characterized by TGA, IR, XRD and BET.The characterization of adsorption property of gas storage materials is pressure-composition-temperature curves. After comparing different schematics of testing apparatus in documents, the differential pressure testing schematic was chosen to guide the building of the testing apparatus.The differential pressure testing apparatus consists of two symmetrical parts with completely identical volume. The pressure used to measure adsorption uptake is the differential pressure of the two symmetrical parts with one of them loaded gas adsorption materials. Compared with Sievert-type apparatus, the differential pressure filtered out the pressure fluctuation caused by the fluctuation of environment temperature. With this improvement and the improvement of accuracy of differential pressure sensor, the accuracy of adsorption measurement was improved. The measurement of the novel coordination framework material synthesized confirmed the improvements of this apparatus.