甲烷无氧制乙烯单铁中心活性位形成机制的原位XAFS研究

With the energy structure and strategy changing in China, natural gas has gradually become an important energy resource component. Thus the exploration of a more cost and resource effective route for the utilization of methane which is the main component of natural gas plays a vital role in the further development of energy industry in our country. Under such situation, the conversion of methane to high value-added chemicals, such as ethylene and aromatics has revived heated research interest around the world. This research program aims at conducting a more comprehensive study on the formation mechanism of the single iron active site during the pre activation of the non-oxidative methane to ethylene process with the aid of advanced in-situ X-ray absorption fine structure (EXAFS). More specifically, from in-situ EXAFS we can get the real time changes of the surface reconstruction, chemical environment, coordination structure and coordination number of the iron species, thus helping to gain more insight into the structure-activity relationship of the single iron based catalyst. Additionally, combined with DFT calculations, we can further reveal the formation mechanism of the single iron active site under reactive atmosphere and at the same time get the rate-determining step, which help for purposefully optimizing the catalyst and then reducing reaction temperature and improving the stability of the catalyst. In a word, this program will offer valid experimental evidence and theoretic guide for optimizing the catalyst for the non-oxidative methane to ethylene process and thus enrich the fundamental theory of this process and promote the development of nature gas industry.

高效利用甲烷已成为制约我国能源工业发展的重要环节，特别是将其转化为高附加值的化学品（如乙烯等）重新激起了世界范围的兴趣，同时也是改善我国能源结构的重要步骤。本项目旨在利用先进的原位X射线吸收精细结构谱对铁基催化剂在无氧催化转化甲烷制乙烯过程中预活化诱导单铁中心活性位的形成进行系统研究，主要针对催化剂预活化过程中铁物种的表面重构、化学状态、配位结构和配位数进行原位分析，理解催化剂的构效关系。并辅以DFT理论计算工具，深入探讨和揭示气氛诱导单铁中心活性位的形成机制、速控步骤；同时在此基础上实现优化改进催化剂，进而降低反应温度和提高催化剂稳定性的目的。本项目将为新型甲烷无氧直接制乙烯催化剂的优化改进提供可靠的实验依据和理论指导，丰富和发展甲烷无氧直接转化的理论基础，推动天然气和页岩气化工利用的实用化发展。

高效利用气态碳氢资源（甲烷）已成为制约我国能源工业发展的重要环节，将这种丰富的资源转化为燃料和高附加值的化学品（特别是低碳烯烃）重新激起了世界范围的兴趣，同时也是改善我国能源结构的重要步骤。基于 “纳米限域”催化新概念，开发了II代Fe©SiO2 涂覆催化剂具有较高的工业应用价值。我们与中石油、SABIC共同对甲烷无氧制烯烃和芳烃项目进行工程放大研究。并辅以先进原位表征技术和DFT理论计算工具，深入探讨和揭示活性位结构、自由基引发机制、链增长过程、速控步骤及催化机制。实现了甲烷无氧制乙烯过程的实验室放大，同时为新型甲烷无氧直接制乙烯、苯和萘过程提供可靠的实验依据和理论指导，丰富和发展甲烷无氧直接转化的理论基础，推动天然气和页岩气化工利用的实用化发展。开展先进的天然气（甲烷）制乙烯和芳烃技术，不仅对我国的社会经济可持续发展有重要意义，而且在非石油路线发展化学化工的战略需求中亦可发挥积极的作用。