金属有机框架UiO-66的制备及储氢性能:微波与传统溶剂热制备的比较

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

  • 摘要: 因结构设计性强和孔隙可调控等优点,MOFs材料的高效制备已成为固态储氢领域的重要课题。然而其高效制备目前仍面临工艺复杂、周期长和效率不高等关键瓶颈。微波辅助合成是一种新兴的技术,它利用微波外场来强化多孔材料制备过程中的传质传热和反应行为,从而有望提高MOFs材料的制备效率。这种方法被认为是实现MOFs材料高效制备的重要发展方向。本工作重点开展了面向高效储氢的UiO-66材料微波法和传统溶剂热法制备的对比研究。通过调整晶化温度和晶化时间制备了不同结构和形貌的UiO-66,优化了材料微波法制备工艺,获得了最优制备条件为120 ℃、1.0 h,其比表面积为1561 m2/g。为了深入理解材料的储氢性能,建立了UiO-66的微观结构与其储氢性能之间的有效关联。实验结果表明,所制备的材料在77 K和5 MPa的条件下,氢气吸附量达到了3.8%。此外,还构建了准一级、准二级动力学方程和颗粒内扩散模型定量描述UiO-66吸氢过程的动力学规律和调控机制。通过本论文UiO-66材料储氢的相关研究,可为MOFs材料的高效制备及储氢机制提供理论基础和技术支持,为多孔材料固态储氢应用提供参考。

     

    Abstract: 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.

     

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