Pt-M双金属纳米晶的控制合成及其催化性能研究

Bimetallic nanocrystals (NCs) show a synergy associated with two different metals, producing specific physical and chemical properties. Catalytic properties of bimetalic NCs not only associate with their sizes and morphologies, but also depend on composition-dependent surface structure. Therefore, it is complicated and difficult to study the corelation between structures and properties of bimetallic NCs. This project addresses synthesis of Pt-M(Sn, Zn, Ni, etc.) NCs with controllable composition, size, morphology and stucture, and study on their catalytic dehydrogenation for light alkanes. In order to improve selectivity and increase the ability of catalyst resistance to carbon deposition, the structures of Pt-M bimetallic NCs and reaction mechanism of catalytic dehydrogenation will be investigated, which will be based on catalyst design and preparation, combination of characterization, reactivity evaluation, kinetic study and theoretic calculation. Co-reduction, seeded-growth, and noble-metal-induced-reduction strategies are very effective for generating bimetallic NCs with well-controlled nanostructures. Combined with multiple detailed characterizations, fundamental problems in catalysis concerning sturcture-properties of active sites will be studied. We hope that this project will provide a theoretical basis and practical guideline for devolpment of high-efficiency and stable Pt-M catalysts, and a new way to comprehensive utilization of light alkane in refinery.

双金属纳米晶联合了两种金属的特性，同时因两种金属协同作用而具有独特的物理化学性质。双金属纳米晶催化性能依赖于晶体的尺寸和形貌，也依赖于受组成影响的表面结构，由此导致双金属纳米晶活性中心构效关系的研究复杂和困难。本项目拟开展组成、尺寸、形貌和结构可控的Pt-M(Sn、Zn、Ni等)双金属纳米晶的调控合成及其在低碳烷烃脱氢制烯烃反应中的催化应用。围绕提高脱氢选择性和提高抗积炭性能，项目从设计、制备催化剂入手，结合物化表征、反应评价、动力学研究和理论计算，开展Pt-M双金属纳米晶的结构解析及丙烷催化脱氢反应机理的应用基础研究。重点采用共还原等方法调控合成双金属纳米晶，综合多种表征技术研究活性中心构效关系等催化基本科学问题。以期通过本研究为开发高效稳定的Pt-M脱氢催化剂提供理论基础和指导，为我国炼厂低碳烷烃综合利用提供新途径。

双金属纳米晶协同两种金属的特性而具有独特的物理化学性质，广泛应用于加/脱氢催化反应中。双金属纳米晶催化性能依赖于晶体的组成、尺寸和形貌影响的表面结构，由此导致双金属活性中心构效关系的研究复杂和困难。近年，由于丙烯需求量逐年持续，工业上大规模推广丙烷脱氢丙烯生产工艺，但由于反应温度高，催化剂反应机理研究困难以及催化剂快速失活需要反复再生。本项目研究中设计合成一系列组成、尺寸、形貌和结构可控的Pt-M（Sn、Ga、Zn、Pd、Fe、Co、Ni等）双金属纳米晶，通过大量条件实验筛选出PtSn、PtGa和PtZn纳米晶对丙烷脱氢反应表现出结构敏感性；通过研究开发了氢气再生催化剂方法，与传统惰性气体吹扫和氧气烧炭方法相比，大幅降低失活率。本研究对解释丙烷脱氢活性中心构效关系，开发高效稳定的脱氢催化剂和工艺方法有指导意义。依托本项目开发的双金属纳米晶在肉桂醛加氢、硝基苯加氢、CO氧化等反应中也表现出较好的催化性能和结构敏感性。