Preparation and hydrogen storage properties of metal-organic framework UiO-66: Comparison of microwave and conventional hydrothermal preparation

The efficient preparation of MOFs materials has become an important issue in the field of solid-state hydrogen storage due to the advantages of strong structural design and tunable pores. However, its efficient preparation is still facing key bottlenecks such as process complexity, long cycle time and low efficiency. Microwave-assisted synthesis is an emerging technology that utilizes microwave external fields to enhance the mass and heat transfer and reaction behavior during the preparation of porous materials, thus promising to improve the preparation efficiency of MOFs materials. This method is considered to be an important development to realize the efficient preparation of MOFs materials. This work focuses on the comparative study of microwave and conventional solvothermal preparation of UiO-66 materials for efficient hydrogen storage. UiO-66 with different structures and morphologies were prepared by adjusting the crystallization temperature and crystallization time, and the preparation process of the material by microwave method was optimized to obtain the optimal preparation conditions of 120 ℃, 1.0 h, and its specific surface area of 1561 m²/g.In order to gain a deeper understanding of the hydrogen storage properties of the material, we have established an effective correlation between the microstructure of UiO-66 and its hydrogen storage properties. The experimental results showed that the hydrogen adsorption of the prepared material reached 3.8% at 77 K and 5 MPa. In addition, quasi-primary and quasi-secondary kinetic equations and intra-particle diffusion models were constructed to quantitatively describe the kinetic laws and regulatory mechanisms of the hydrogen adsorption process of UiO-66. The research related to hydrogen storage in UiO-66 materials in this thesis can provide theoretical basis and technical support for the efficient preparation and hydrogen storage mechanism of MOFs materials, and provide a reference for the application of solid-state hydrogen storage in porous materials.