氮碳包覆的非贵金属负载型复合催化剂的构建及其丙烷脱氢反应研究

Propane non-oxidation dehydrogenation (PDH), as a kind of propene production and shale gas utilization technology, has attracted much attention during these years. Though with the advantages of low toxicity and inexpensive price, the non-noble metal-based catalysts have still been limited by coke deposition, loss of active sites and low stability. Herein, we plan to use nitrogen doped carbon materials to modify the supported non-noble metal-based hierarchical catalysts. With the addition of nitrogen component, the electron transfer between nitrogen species and metal components would modulate the electronic structure and chemical environment of metal component which could further improve the catalytic activity and the anti-sintering ability of the catalysts. Meanwhile, the use of hierarchical support could increase the catalyst stability by enhancing the diffusion of coke precursors and enlarging the coke containing ability. Combining with the characterizations and chemical kinetics method, it is proposed to clarify the improvement mechanism of nitrogen species and influence on the catalyst deactivation process. With developing the composite of nitrogen-doped carbon materials with hierarchical materials and expanding the utilization field of nitrogen-doped material, the project will also lay the foundation for the development of highly efficient and high stable non-noble metal-based catalysts with low toxicity for PDH in fundamental and theoretical research to increase the propane utilization and propene production.

丙烷无氧脱氢反应是增产丙烯、利用页岩气的重要途径之一，非贵金属基丙烷脱氢催化剂具有毒性较低、价格低廉等优势，但其存在易积炭、活性位易失活以及催化剂稳定性待提高等问题。本项目拟通过多级孔材料作为载体，构筑氮碳组分包覆的非贵金属基催化剂，一方面利用氮碳物种与金属组分之间的电子迁移作用调变金属组分的电子性质及化学环境，提高催化剂丙烷无氧脱氢反应活性及其抗烧结能力；另一方面，使用多级孔材料作为催化剂载体，通过强化反应中积炭前驱体的扩散、增加催化剂容炭量，提高催化剂稳定性。结合表征手段及化学动力学方法，明确氮碳组分引入对金属组分上丙烷脱氢反应的促进作用机制，及其对反应机理和催化剂失活过程的影响。本项目的实施，将在发展多级孔与氮碳复合材料、拓展氮碳材料应用领域的基础上，为开发高效稳定且低毒廉价的非贵金属基丙烷脱氢催化剂奠定理论研究基础。

乙烯丙烯是重要的基础化学品，主要通过蒸汽裂解和催化流化裂解进行生产。近年来，随着我国双碳目标的制定，开发新型环保的低碳烯烃生产技术受到广泛关注。其中，丙烷脱氢是一种重要的增产丙烯技术。在丙烷脱氢研究过程中，由于Pt催化剂成本高且容易失活、Cr催化剂存在一定的环境危害，因此，开发低成本、环境友好、高效稳定的非贵金属基催化剂逐渐成为热点，也是丙烷脱氢领域的重要研究方向之一。本项目通过一种氮掺杂碳材料保护策略，可有效提高非贵金属基催化剂（Zn、Fe和Co）的丙烷脱氢活性。氮物种的存在可以锚定金属位点和调控金属电子密度，提高催化剂的稳定性和选择性。采用分子筛等材料作为载体，进一步促进金属物种分散。通过原位及非原位表征分析发现，氮物种的引入，可以有效调控金属物种类型及其对丙烯脱附能力，从而提高催化剂性能。以Fe基催化剂为例，引入氮掺杂碳物种后，其丙烷脱氢性能是改性前催化剂的近3倍，且稳定性显著增强。本项目的开展，扩展了氮掺杂碳材料的应用范围并拓宽对金属组分改性思路，也为后续开发高效非贵金属丙烷脱氢催化剂，提供有效的基础数据。