基于MOFs的新型金属催化剂复合轻质金属高容量储氢材料的设计、制备与热力学研究

The key issues of this project focus on the preparation of nano-catalysts from metal organic framework materials (MOFs) and their catalytic effect on properties of high-capacity hydrogen storage materials like Li/NaAlH4,etc.. According to our preliminary experimental results and research basis, this project has fristly put forward a new idea of combining design of MOF materials and nano-catalyst preparation to improve the hydrogen absorption and desorption performance of high-capacity hydrogen storage materials. Using thermal analysis,the Sievert method, XRD, TEM, etc. to characterize the thermodynamic and kinetic characteristics of nano-catalytic high-capacity hydrogen storage materials. The project will mainly focus on studies of morphology, structure and catalytic mechanism of nano-catalysts and nano-catalytic lightweight metal hydrogen storage composite based on systematic experimental studies and theoretical calculations. We try to clarify the following issues: 1. Controllable preparation of nano catalysts by metal organic framework materials and their influence factors; 2. Screen of the nano-catalyst with suitable chemical composition and particle size for specific high-capacity hydrogen storage materials; 3. Characteristics and exploring of law of kinetics and thermodynamics of nano-catalyst doped high-capacity hydrogen storage material system; 4. The inner relationship between microstructure evolution and hydrogen absorption and desorption performance; 5. Determination of the active component of nano-catalyst and revealing of the catalytic mechanism. This project will be of great significance not only for in-depth understanding of the hydrogen adsorption / desorption mechanisms of nano-catalytic high-capacity hydrogen storage materials, but also for expanding the applications of nano-catalysts for R&D of new hydrogen storage materials.

本项目针对金属有机框架(MOFs)材料制备纳米催化剂及其储氢材料存在的关键性问题，在前期实验研究基础上，首次提出MOFs材料设计与纳米催化剂制备相结合新思路来改善高容量储氢材料（Li/NaAlH4等）的吸放氢性能，利用热分析方法、Sievert方法、XRD等表征纳米催化储氢材料的热力学和动力学特性，侧重于纳米催化剂和催化复合轻质金属储氢材料的微观形貌、结构和催化机理开展系统的实验研究，结合理论计算研究，力求阐明：（1）由MOFs可控制备纳米催化剂及其影响因素；（2）适于高容量储氢材料的纳米催化剂组分与粒子尺寸筛选；（3）复合储氢材料体系的动力学和热力学性质变化规律；（4）吸放氢过程中微观结构演变规律与吸放氢性能之间的内在联系；（5）纳米催化剂的催化活性组元及其催化作用机理揭示。本项目研究对于深入认识纳米催化剂催化高容量储氢材料的吸/放氢机制，设计制备新型优异性能储氢材料具有重要意义。

氢能领域的核心技术包括氢气的大规模制备、存储、运输及转化利用。其中，现存的储氢技术难以满足实际应用的需要，已成为制约氢能发展的瓶颈之一。本项目针对金属有机框架材料制备纳米催化剂及其储氢材料存在的关键性问题，提出MOFs 材料设计与纳米催化剂制备相结合新思路来改善高容量储氢材料的吸放氢性能，利用热分析方法、Sievert 方法、XRD 等表征纳米催化储氢材料的热力学和动力学特性，侧重于纳米催化剂和催化复合轻质金属储氢材料的微观形貌、结构和催化机理开展系统的实验研究。为了克服储氢材料催化剂制备及操作困难（配位氢化物对水、溶剂、氧气、温度等的敏感性），我们发展了一种新的纳米催化剂制备技术—高温固相法：以金属有机骨架化合物(MOFs)为前驱体，通过在不同气氛下高温煅烧便可得到尺寸均匀且组成可调的催化剂。具体事例为高温固相法制备的碳包覆镍钴合金(NiCo@C)催化剂，其外层是少量的碳，核为镍钴合金，尺寸分布十分均匀，且核心的金属成分可以调整。通过球磨的方式将此催化剂与LiAlH4进行了简单的复合，可将LiAlH4的分解脱氢降低至43°C。另一方面低温脱氢动力学也得到了改善，脱氢活化能得到了大幅降低。由于催化剂的用量只有1 wt%，体系的含氢量并没有明显变化。随着催化剂含量的进一步增多，脱氢起始温度降到了在36 °C。项目执行过程中，发表论文15篇，其中7篇为SCI收录，8篇发表在中文核心期刊上，申请中国发明专利9件，其中授权4件。培养2名博士研究生和7名硕士研究生。本项目对于拓展纳米催化在新型高容量复合储氢材料设计、制备和应用方面的研究，具有重要的科学意义和实用价值。