甲烷存储、制备新思路-轻金属氢化物-CO2材料的甲烷化特性及机理

The methane storage with high capacity and methanation of carbon dioxide are the effective methods to alleviate the energy shortage and carbon dioxide excess problems. The studies indicate that combining the light metal hydrides with carbon dioxide is a promising way to prepare a kind of methanation material with high energy capacity that can release methane spontaneously under the mild condition. For this project, fundamental research will be performed on the design and preparation of the light metal hydrides-carbon dioxide methanation material, the analysis of its methanation mechanisms, as well as the control of its methanation performance. We will establish a theory for designing structure and composition of the light metal hydrides-carbon dioxide methanation material by the theoretical calculation method and develop techniques for preparing the light metal hydrides-carbon dioxide methanation material. The evolution of structure and composition in the processes of methanation will also be studied experimentally and theoretically to clarify the methanation mechanisms and reveal the relation of structure and composition with methanation performance. Moreover, the methane yield, component content in the product,thermodynamic and kinetic properties will be controlled through the strategies, such as material size control, optimization of composition, the change of reaction condition, catalyst introduction, and so on to explore the methods of improving the methanation performance. Obviously, conduction of the research will be helpful for realizing the utilization of carbon dioxide as a resource and lay the experimental and theoretical foundation for developing a safe, convenient and high-performance methane storage and preparation material with high energy capacity using the light metal hydrides and carbon dioxide.

甲烷的高密度存储及二氧化碳（CO2）甲烷化都是缓解能源短缺与CO2超标的有效方法。研究发现将轻金属氢化物与CO2联合有希望制备出具有高能量密度、在温和条件下自发甲烷化的能源材料。因此，本项目拟从轻金属氢化物-CO2甲烷化材料的设计与制备、甲烷化反应机理分析、甲烷化性能调控方面开展相应的基础研究。通过模拟计算建立轻金属氢化物-CO2甲烷化材料的成分和结构设计理论，发展其合成制备技术；理论结合实验地探讨其甲烷化过程中的成分、结构演变规律，阐明其甲烷化反应机理，揭示其成分、结构与甲烷化性能的关系。在此基础上，通过材料组分优化、尺度调整、反应条件控制、催化剂引入等方法进行甲烷产率、产物组分含量、热力学及动力学性能的调控，探索改善材料甲烷化性能的方法。显然，此研究有助于实现CO2的资源化利用，将为发展具有高能量密度、安全、便利、高效的轻金属氢化物-CO2甲烷储运与现场制备材料奠定实验和理论基础。

开辟新方法、研制新材料来实现高效CO2甲烷化和甲烷存储仍是当前国际研究的重点。本项目发现与氢气还原CO2甲烷化反应相比，利用轻金属氢化物还原CO2更有利于甲烷化反应的进行。本项目建立了轻金属氢化物（LiH、NaH、MgH2、CaH2、LiAlH4、NaAlH4、LiBH4、NaBH4）在室温机械球磨条件下或者温和热化学条件下还原CO2甲烷化反应的甲烷产率、产物组分含量的测定方法。探索了轻金属氢化物在机械化学和热化学条件下还原CO2甲烷化性能，发现轻金属氢化物在温和条件下可以高效、高选择性地还原CO2为甲烷化，甲烷化选择性接近100%, 甲烷化产率可达89%。分析、表征了轻金属氢化物-CO2材料甲烷化过程中的成分、结构和组织形貌并探明了其成分、结构演变规律；阐明了轻金属氢化物还原CO2甲烷化反应机理，发现原位生成的无定型碳在甲烷的形成过程中起着很重要的作用。掌握了轻金属氢化物-CO2材料成分、结构、反应时间、反应温度、CO2压力等与其甲烷产率、产物组分含量的关联性。轻金属氢化物-CO2甲烷化体系有希望成为在温和条件下自发反应、具有高能量密度、高效的甲烷储运与现场制备材料。发展轻金属氢化物-CO2甲烷化材料适合甲烷燃料的现场供应，对提高清洁能源甲烷在一次能源消费中的比重、减少CO2排放方面都有积极促进作用。