Mo基分子筛催化剂在甲烷无氧芳构化反应中积炭失活研究

The methane nonoxidative dehydroaromatization (MDA) has attracted much attention from various research groups in the world during recent decades owing to the important scientific value and potential application prospect. The coking-caused deactivation of the Mo-based zeolite catalyst in the MDA is considered the main problem to be tackle for its commercial application, because the coking formed by methane cracking is more thermodynamically favorable than the formation of the aromatic under nonoxidative conditions. In this project, the static properties and dynamic behavior of various coking (include fullerene-based coking and confined carbon), the formation, growth mechanism and effect of fullerene-based coking and confined carbon, as well as structure-performance relationship between the hollow capsule architecture and various coking will be investigated by the hierarchical elimination method, operando spectroscopy and steady state isotopic transient kinetic analysis (SSITKA) in the MDA process. The mechanism of methane activation and coking-caused deactivation will be disclosed, and the effect of various coking on the structure and catalytic properties of the Mo-based zeolite catalyst will be elucidated in the MDA reaction. Our project lays the theory foundation for the design of the highly stable and coking-resistant catalyst, and makes the MDA process more stable.

甲烷无氧芳构化反应由于兼具重要的科学价值和潜在的应用前景，因而一直以来备受国内外学者的广泛关注。目前限制甲烷无氧芳构化反应工业化应用的瓶颈在于催化剂积炭失活问题。本课题拟通过“分级消除”方法来研究Mo基分子筛催化剂在甲烷无氧芳构化反应中各种类型积炭（包括富勒烯积炭和限域碳）的静态性质和动态演变行为，其次采用实时原位技术和稳态同位素瞬变动力学分析研究富勒烯积炭和限域碳的形成、生长机理和作用机制，最后探索分子筛中空胶囊结构与各种类型积炭之间的构效关系。阐明甲烷无氧芳构化反应中Mo基分子筛催化剂上甲烷活化和积炭失活机理，揭示富勒烯积炭和限域碳对催化剂结构和反应性能的影响规律。本课题为抗积炭、高稳定性催化剂设计奠定了理论基础，进一步提高甲烷无氧芳构化过程的稳定性。

目前限制甲烷无氧芳构化反应工业化应用的瓶颈在于催化剂积炭失活问题，而积炭失活机理尚不清晰。本研究采用“分级消除”策略研究富勒烯积炭和限域碳对MDA性能的影响。利用原位UV-Raman和高分辨脉冲实验阐明了富勒烯积炭对甲烷无氧芳构化反应(MDA)过程的影响；并研究了Mo/中空胶囊HZSM-5催化MDA反应中积炭分布对MDA失活贡献的影响；采用高分辨脉冲反应结合同位素标记技术研究MDA反应过程中碳催化循环路径以及限域碳的作用；最后，采用operando XAS研究MDA反应中Mo物种的演变行为。本项目从分子原子水平上深刻认识Mo基分子筛催化MDA反应过程中积炭失活机理。为抗积碳、高稳定性催化剂设计奠定了理论基础，进一步提高甲烷无氧芳构化过程的稳定性。在青年基金的支持下，共发表Catalysis Science & Technology封面论文两篇和燃料化学学报一篇，协助培养硕士研究生一名。