Synthesis, Characterization And Hydrogen Storage Capability Of Metal-organic Complexes

Hydrogen energy holds the unparalleled potential development valueas a clean and non-polluting new energy. However, a safe and economicaltechnique for H2storage is a key part of the hydrogen energy developmentand utilization. Metal-organic complexes are a class of new materialsassembled by the metal center ions and organic ligands, which has broadapplication prospect in the field of hydrogen storage because of their highspecific surface area, large pore volume and tunable pore size.The characterization of hydrogen gas storage capability of materials ispressure-composition-temperature curves. Design of the testing apparatushas great significance to the research and development of hydrogen storagematerials. An apparatus for measuring hydrogen storage properties wasimproved and debugged under the mechanism of volumetric differentialpressure. The apparatus can operate over a wide range of temperature,77K-573K, and H2pressure,0-30MPa with good actual operation and highaccurate results.A hexacarboxylic acid ligand1,3,5-tris(3',5'-dicarboxyl-phenyl) benzene (H₆L) was prepared through SUZUKI couping reaction. And thenovel Cu(II) hexacarboxylic complexes material was synthesized bysolvothermal reaction using Copper nitrate and H₆L as the reactants,DMSO,DMF and deionized water as the solvent. The effects of moorerate,reaction temperature,reaction time,solvent,heating and cooling rate onsynthesis were studied in experiments.The experiments results indicatedthat the products with highest yield were obtained at Cu(NO3)2·3H2O/H₆L(mol/mol)=6, the reaction temperature of90℃,reaction time for24hand DMF/DMSO/H2O(v:v:v)=5:5:1.The big crystal was growed byselecting appropriate heating and cooling rate.The properties of the resulting products were characterized by usingXRD,EA,TG,IR,SEM and low temperature nitrogen adsorption-desorptiontechniques. The results showed that the product had rich microporousstructure, the BET and Langmuir specific surface area was respectively2166.3m²·g^-1and3484m²·g^-1, and the total pore volume Vp(N2,0.997) was1.24cm³·g^-1.The material showed a absolute H₂uptake of7.23wt%at77Kand7.4MPa, and an H2uptake of0.61%at298K and5.4MPa, whichshowed a good hydrogen gas storage capability.