低碳烷烃脱氢锡基催化剂的活性位识别及反应机理研究

Dehydrogenation of alkanes, as an important route for the utilization of abundant light alkanes and the production of high-valued alkenes, is particularly concerned. Although satisfactory performances can be achieved over commercially applied platinum and chromia-based catalysts, high cost and environmental issues are inevitable. Furthermore, frequent regeneration is necessary due to the fast deactivation. Therefore, the development of a novel class of economically efficient and environmental-friendly catalyst, with a long regeneration period, is the key to widespread application of dehydrogenation processes. Recent research indicated that Sn, generally used as the promoter of Pt-based catalysts, exhibited excellent dehydrogenation performance. In this project, the relationship between catalyst structure and dehydrogenation performance will be studied to determine the active sites. Moreover, the catalyst composition will be modified to improve the dehydrogenation performance. Based on the above study, the adsorption state of alkane molecules on the catalyst surface will be investigated to explore the reaction mechanism. Finally, the deactivation origin and regeneration mechanism will be revealed, and effective methods to lengthen the regeneration period are to be studied. This project will not only benefit the deep understanding of alkane dehydrogenation, but also provide theoretical guidance in the design and development of novel dehydrogenation catalyst.

烷烃脱氢作为合理利用丰富低碳烷烃资源、制备高附加值烯烃的一条重要途径，日益受到人们的重视。目前工业化脱氢技术多采用Pt基或Cr基催化剂，二者存在生产成本高和环境污染等问题，此外，催化剂易结焦失活，需频繁再生。因此，长再生周期新型低价环保催化剂的开发，是进一步推广烷烃脱氢技术的关键。研究发现，常用作Pt基催化剂助剂的Sn可单独催化烷烃脱氢反应，具有高的脱氢活性及烯烃选择性。本课题将对锡基催化剂的结构特点及脱氢性能进行考察，建立其构效关系，识别脱氢活性位；调控催化剂组成，优化活性物种的催化作用；考察烷烃分子在锡基催化剂表面的吸附态，明确锡基催化剂的作用机制及烷烃分子的反应历程；最后，对催化剂的失活与再生机制进行考察，探索锚定锡物种和稳定催化剂组成的可行方法，延长催化剂再生周期。本项目不仅对深入认识低碳烷烃脱氢过程具有重要意义，而且为新型非贵金属环保型脱氢催化剂的设计与开发提供了理论指导。

烷烃脱氢技术可合理利用低碳烷烃资源，高效生产高附加值低碳烯烃，日益受到人们的重视。工业化的脱氢技术所用催化剂非Pt即Cr2O3，其价格高昂和环境污染的问题制约了烷烃脱氢技术的进一步推广。本项目初步开发了新型低价环保锡基丙烷脱氢催化剂，并在催化剂脱氢作用机制、失活及再生性能等方面取得了系列研究结果。主要包括以下几个方面：（1）识别负载型锡基催化剂的脱氢活性相，建立了催化剂的组成、结构与其催化脱氢反应性能之间的关系；（2）探索了锡基催化剂的脱氢机制，推测了烷烃分子的反应历程；（3）明确了锡基催化剂失活机制，并对反应过程中锡物种的流失情况进行检测；（4）针对金属锡熔点低易流失及团聚的问题，提出了有效的锡基催化剂稳定性强化策略。项目执行期间发表论文14篇，SCI收录12篇。授权国家发明专利5项，美国发明专利2项。协助培养了1名博士研究生，2名硕士研究生以及3名本科生。本项目在理论上有助于深化人们对烷烃催化脱氢本质的认识，在实际上对于烷烃脱氢制烯烃新技术的开发有一定的指导意义。