丙烷脱氢Pt系合金催化剂的理论筛选与科学构建

Propane dehydrogenation (PDH) is an important and fast-developing process for on purpose propylene production. This project focus on Pt-based alloy catalysts as PDH catalysts. The density functional theory is used to determine the surface structure of different Pt alloys and the interface between the alloys and the supports under different reaction conditions. The thermodynamic and kinetic data, combined with microscopic kinetic simulations, are used to analyze the key factors affecting dehydrogenation activity, olefin selectivity and carbon deposition. Subsequently, the target catalyst is controlled and synthesized, and the interaction between the alloys and the supports is enhanced by the modified supports to achieve high dispersion of the active site on the surface and high temperature stability. In-situ characterization technologies under reaction conditions are used to further understand the structure-activity relationship of Pt-based alloy catalysts for the catalyst development and industrial application of propane dehydrogenation to propylene. A combined theoretical and experimental study, including Density Functional Theory calculations, ultra-high vacuum surface science study and in-situ experimental measurements, will be applied to tackle the key questions during PDH reaction, which will help to design new Pt based catalyst. The proposed research will improve the short chain hydrocarbon conversion efficiency and reduce the olefin production cost.

丙烷脱氢是近年来快速发展的丙烯直接生产新工艺，是一条有重要实用价值和战略意义的低碳烯烃生产路线。本课题以Pt系合金催化剂为目标催化剂，运用密度泛函理论，确定不同反应条件下，不同Pt系合金的表面结构，计算合金、载体表面及合金与载体界面处丙烷脱氢和积碳生成反应的热力学和动力学数据，结合微观动力学模拟，分析影响脱氢活性、烯烃选择性和积碳形成的关键因素。在此基础上，对目标催化剂进行可控合成，通过改性载体增强合金和载体间相互作用，实现活性位在载体表面的高度分散及高温稳定，结合反应条件下的原位表征技术，深入认识Pt系合金催化剂的构效关系，为新型丙烷脱氢制丙烯催化剂的开发和工业应用做准备。本项目通过密度泛函理论计算、超高真空表面实验、原位表征等一系列理论结合实验的方法探究丙烷脱氢反应机理，指导设计新型Pt系催化剂，通过可控合成开发新型高效的丙烷脱氢催化剂，为低碳烷烃活化直接制取化学品提供了新的思路。

本项目围绕丙烷脱氢Pt系合金催化剂的理论筛选和科学构建，从Pt系合金中Pt的局部配位环境对反应性能的影响机制、助剂与载体对Pt系催化剂活性位点的调控与强化机制、催化剂在工艺放大过程中的应用规律等方面开展了系统而深入的研究。通过密度泛函理论计算（DFT），阐明了丙烷脱氢反应的中间体吸附构型与活性位的几何、电子结构的关系，提出描述活性位的“孤立度”描述符，实现了Pt系合金催化剂的性能预测；在低负载量下Pt活性位精准设计方面，提出助剂与Pt合金化构筑催化活性位点的方法，精准调控Pt系催化剂活性位点的几何和电子结构，发明了铂锌有序金属间合金催化剂，实现了丙烯的高选择性生产；开发出复合金属氧化物载体，调控反应中间物种的吸附与迁移，实现了活性位点的高度分散和高温稳定，提升了催化剂的反应和再生稳定性；提出了反应器装填形式的优化方案，开发了丙烷脱氢高能效循环控制工艺，开发出副产氢气下游高附加值利用工艺，提升了能量利用效率和产品价值。本项目为新型丙烷脱氢制丙烯催化剂的开发和工业应用做好了准备。