类水滑石/炭复合材料对油田驱采出气中CO2的分离和光催化转化研究

It was found in previous studies that Ti/Li/Al-LDHs is a solid adsorbent with good CO2 adsorption and regeneration properties. In this project, a new kind of hydrotalcite/ carbon composites, Ti/Li/Al-LDHs-C was designed and synthesized for the separation and photocatalytic conversion of CO2 for the recycling and utilization of CO2 in the CO2/CH4 flooding produced gas of oilfields. Using density functional theory and molecular dynamics simulations, the key factors affecting the preparation of materials will be explored, and characteristics of the composition structure, crystal structure as well as the surface structure of the new composites will be revealed. This proposal will mainly investigate changes of the structure, morphology and functional groups of Ti/Li/Al-LDHs, and effect laws of CO2/CH4 adsorption, separation and photocatalytic conversion, with the doping of the carbon to establish the relationship between materials’ structures and performances and the regulation method. The reaction mechanism of Ti/Li/Al-LDHs-C for separation and photocatalytic conversion of CO2 in CO2/CH4 will be found. The relationship between structure and material photocatalytic selectivity will be further studied. Thermal stabilities and regeneration mechanisms of the new materials will be also revealed, in order to provide a theoretical basis for promoting the new materials’ application in separation and utilization of CO2.

通过前期的研究发现Ti/Li/Al-LDHs是一种具有良好CO2吸附性能和再生性能的功能材料。为此，针对目前油田驱采出气CO2/CH4的特性，本项目提出设计合成一种新型类水滑石/炭复合材料（Ti/Li/Al-LDHs-C），对CO2/CH4中的CO2进行分离、光催化转化，完成CO2的再次回收利用。利用密度泛函理论和分子动力学模拟方法，研究影响材料制备关键因素，揭示新型复合材料的组成结构、晶体结构和表面结构特征；重点探讨炭掺杂后的Ti/Li/Al-LDHs的结构、形貌和表面官能团等变化，及其CO2/CH4吸附分离、光催化转化特性影响规律，建立材料结构与性能关系及其调控方法；探明新材料Ti/Li/Al-LDHs-C对CO2/CH4分离和光催化过程的反应机理；进一步总结材料结构与光催化选择性关系研究，探讨新材料的热稳定性及再生机理，为促进材料在CO2分离和利用中推广应用提供理论基础。

本项目基本完成了研究任务，并在此基础上拓展了研究方向，深挖研究机理，为CO2和CH4混合气体的综合利用转化提供新思路和研究基础。本项目围绕CH4/CO2光催化转化问题，发展了类水滑石等光催化材料的精准合成方法和宏量制备技术，探明了材料的调变规律；利用X射线吸收光谱、同步辐射红外线光谱、原位拉曼光谱、近常压X射线光电子能谱等表征手段，结合理论计算，分析出CH4/CO2分子在类水滑石等复合材料表界面的吸附及光催化转化机理；利用超快吸收光谱等技术，结合理论计算，研究催化反应过程中电荷分离与复合、电子激发与弛豫等光电荷的动力学行为，在电子层面理解光催化体系中的微观作用机制。通过三年的研究和努力，本项目已经在CH4、CO2光催化转化方面取得了一定的成果，项目成果已在Angew. Chem. Int. Ed、Chem. Soc. Rev.等国际重要期刊上发表14篇，其中以通讯作者/第一作者发表论文9篇。申请发明专利2项，出版专著1本。同时，本项目在材料制备和表界面研究，包括电荷转移方面都积累了一定经验，为后期继续的光催化研究奠定坚实基础。