纳米碳催化材料的化学可控制备及其催化反应机理研究

Nano-structure carbon based materials have shown high catalytic activity, high alkene selectivity and long term stability in oxidative dehydrogenation reactions of alkanes. They exhibit significant advantages over traditional metal or metal oxide based catalysts, and have been proven to be potential alternatives to conventional catalysts. However, the nano-carbon catalysis field has been experiencing an unparalleled development of new catalyst synthesis or their applications in new reaction systems but only a slow growth of mechanical interpretations to the nature of carbon-catalyzed reactions, which we believe is even more important to advance our knowledge in related fields. One of the most critical problem that limits the quantitative description of catalytic mechanism and detailed kinetic study is the complexity of the surface functional groups on nano-struture carbon based materials, since the traditional synthesis procedure of nano-carbon catalysts are normally realized through fierce physical or chemical process. Aimed at above problems, here we propose a novel bottom-up procedure based on Yamamoto coupling reactions to fabricate nano-structure carbon based materials with definite chemical composition and structure. Further more，detailed kinetic measurements and mechanical analysis will be performed on these model catalysts, which could provide direct chemical evidence for the identity and quantity of active sites for carbon catalysis and reveal the essence of carbon catalyzed reactions. The intrinsic rate constants obtained from rigorous kinetic measurements can be related to the chemical structure of the catalysts. These fundamental relations between composition and reactivity on well-defined nano-carbon catalysts shed light on the most appropriate descriptions and fair comparisons of reactivity for current carbon based catalysts, and which can also be used to predict the catalytic properties of relevant nano-carbon catalysts with uncertain structure or as the important guidance for new nano-carbon catalyst synthesis.

与传统贵金属或金属氧化物催化剂相比，纳米碳材料在催化烷烃氧化脱氢反应过程中表现出烯烃选择性高，表面积碳少，活性保持时间长，能耗低等优势，其作为一种可再生的环境友好催化剂，在烯烃工业合成领域展现出巨大的应用前景。由常规剧烈物理方法制备的纳米碳材料通常具有复杂的化学组成和结构，传统的光谱或能谱分析方法很难定性或定量描述纳米碳催化反应过程，严重限制了纳米碳催化反应机理和动力学的深入研究。针对这一问题，本项目提出从小分子出发，借用高分子聚合的思想制备具有确定化学组成和结构的功能纳米碳材料的设想，并期望能够利用这些催化活性位点位置和数量确定的纳米碳材料作为模型催化剂，系统研究纳米碳材料催化烷烃氧化脱氢反应的机理和动力学，从而量化描述纳米碳催化反应过程，揭示纳米碳催化剂结构与其催化活性和产物选择性之间的关系，为现有纳米碳催化体系活性的客观评价和比较提供依据，同时为新型纳米碳催化剂的设计和制备提供参考。

纳米碳材料在烷烃氧化脱氢、有机物选择性氧化、氧气电化学还原等多种复杂反应体系中均展现出稳定的催化活性，反应条件温和、目标产物选择性高、绿色、环保、可再生的特点使得纳米碳成为替代传统金属基催化剂的理想材料，纳米碳催化成为材料学和催化化学领域内的热点研究课题。本项目提出从小分子出发，借用高分子聚合的思想制备具有确定化学组成和结构的功能纳米碳材料的设想，并期望能够利用这些催化活性位点位置和数量确定的纳米碳材料作为模型催化剂，系统研究纳米碳材料催化烷烃氧化脱氢反应的机理和动力学，从而量化描述纳米碳催化反应过程，揭示纳米碳催化剂结构与其催化活性和产物选择性之间的关系，为现有纳米碳催化体系活性的客观评价和比较提供依据，同时为新型纳米碳催化剂的设计和制备提供参考。经过近3年的系统研究工作，我们圆满完成了项目申请过程提出的计划。项目取得的主要研究进展包括：1、从有机小分子出发，通过Yamamoto聚合反应，开发具有共轭结构的新型模型纳米碳催化材料（YPB）制备方法。2、将YPB系列模型催化剂应用于硝基苯还原和乙苯氧化脱氢反应中，分别为碳催化的液相和气相反应创建研究平台。3、利用原位光谱技术，电子显微分析，以及化学滴定等手段系统研究气相或液相反应中模型纳米碳催化剂活性位点的定性和定量方法。4、利用催化反应动力学手段在原子或分子尺度上揭示不同反应体系中纳米碳催化作用的本质机制。.项目发表论文9篇，申请中国发明专利1项，合作出版中文学术专著一部，毕业博士研究生2名，硕士研究生4名。项目研究工作成果的学术意义在于从分子尺度上认识纳米碳催化过程的本质，理解非金属纳米碳材料催化活性的来源，掌握催化剂化学组成和结构对其催化活性的影响规律，为新型高效非金属催化材料的设计和应用提供了理论依据。