Study On The Hydrogen Storage Properties And Modification Of Zr-baesd MOFs

Energy is an important support for the development of society and country. The development of new energy has become a hot research topic in recent years. Hydrogen has been widely concerned due to its high combustion heat and environmentally safe combustion products water. However, hydrogen is a gas at room temperature and atmospheric pressure, the density is very small, and easy to burn and explode. So the transport and storage of hydrogen is the key to the application of hydrogen energy. The development of safe, stable and efficient hydrogen storage materials has become a research hotspot for hydrogen utilization. In many current research in hydrogen storage materials, metal organic frameworks (MOFs) are regarded as one of the most promising hydrogen storage materials due to porous structure, diversity, high surface area and low density crystal. They are also widely used in the adsorption and separation of gases, organic catalytic reaction and chemical and biological sensors etc.The work of this paper is to design stable, safe and efficient hydrogen storage materials by means of the molecular simulation, establish the calculation model, and study the properties of crystal structure. In current MOFs hydrogen storage materials, the thermal stability of Zr-based MOFs is excellent. Structural stability can be maintained in water, acetone, benzene, DMF and other organic solvents and acid-base system. Zr-based MOFs have good hydrogen storage properties, and can realize fast hydrogen absorption properties with good cyclic reversibility. This paper studies on hydrogen storage properties and influence factors of Zr-based MOFs materials UiO-66, UiO-67, MOF-801, MOF-802, MOF-808, and MOF-841. Explore modified methods to improve the hydrogen storage properties of Zr-based MOFs, which include the skeleton structure functionalization, Li metal ion doping and the replacement of the center metal ions.This paper researches the adsorption isotherm curves of several MOFs materials in 77K under different pressures, including mass adsorption isotherm and volume adsorption isotherm. We found that the material surface area and porosity are directly influence factors of hydrogen adsorption capacity under high pressures, and the adsorption heat is an important factor of hydrogen storage properties under low pressures. Through the research on the modified methods to improve the performances of the hydrogen storage, the results show that in the skeleton structure functionalization, the introduction of -CN functional group make hydrogen mass adsorption capacity improve 11.7% and -Br functional group make hydrogen volume adsorption capacity improve 17.8%; In the metal Li doping, the effect of hydrogen storage of introducing metal Li by chemical modification method is better than the physical modification method, the chemical modification method improve the mass adsorption capacity by 12.3% and the volume adsorption capacity by 14.5%; In the replacement of center metal, light element Ti replacement can increase the hydrogen storage capacity of the material, which can increase the hydrogen mass adsorption capacity by 19.4%.This paper studied the hydrogen storage properties and influence factors of MOFs materials, and the modified methods to improve the performances of the hydrogen storage, which lays the theoretical foundation for the further research and application of hydrogen storage materials.