CoMo基催化剂MoS2的形貌调控对活性中心的形成和性能的影响研究

CoMo-based catalyst is one of the classic catalysts for hydrodesulfurization (HDS) and sulfur-resistant water-gas shift (WGS) reaction. The understanding of the nature of its CoMoS active sites is fundamentally important to further increase its catalytic activity, while the relationship between MoS2 morphology and the formation and catalytic performance of CoMoS sites is the core of this issue. In this project, we attempt to synthesize a series of supported-MoS2 with different and controllable morphologies by optimizing the preparation and sulfidation conditions, then to in-situ create CoMoS sites on the edges of MoS2 by the chemical vapor deposition method. The effect of MoS2 morphology on the concentration, structure and catalytic activity and selectivity of CoMoS sites will be investigated by low temperature (liquid N2) CO adsorption followed by IR sepctroscopy as well as other characterization methods such as extended x-ray absorption fine structure (EXAFS). And accordingly the structure-activity relationship between MoS2 morphology and catalytic performance will be obtained. It is expected that the findings in this research will be of great importance to the understanding and reasonable designing of highly active CoMo-based catalysts.

CoMo基催化剂是一类经典的加氢脱硫和水煤气耐硫变换催化剂，深入认识其CoMoS活性中心的本质是进一步提高该类催化剂性能的关键，而阐明MoS2的形貌与CoMoS活性中心的形成和性能之间的内在关系是其中的核心所在。在本项目中，我们拟通过设计合成形貌可控的负载型MoS2，利用化学气相沉积法在不同形貌的MoS2边位上原位生成CoMoS活性中心，在液氮温度下以CO为探针分子结合原位红外光谱技术，并综合利用扩展X射线吸收精细结构（EXAFS）等其它表征手段，研究MoS2形貌调控对CoMoS活性中心的数量、结构以及催化活性和选择性的影响，揭示MoS2形貌与CoMo基催化剂性能之间的构效关系，为进一步开发高性能CoMo基催化剂提供理论基础和技术源头。

CoMo基催化剂广泛应用于石化行业加氢脱硫精制以及煤化工行业耐硫水气变换制氢等领域，深入研究MoS2的形貌与活性中心的关系，对设计开发高效CoMo催化剂具有重要意义。在本项目中，我们采用液氮温度下CO为探针分子的原位红外、高分辨电镜、原位XPS、原位拉曼等表征手段，系统研究了载体种类和性质、Co含量、螯合剂、助剂等因素对MoS2形貌的影响，优化合成条件，合成了不同形貌的二维MoS2材料，所合成的MoS2可以从主要暴露一种边位的类三角形逐步调变为同时暴露两种边位的类六边形形貌。在此基础上，我们通过原位技术在不同形貌的二维负载型MoS2的不同边位上设计产生CoMoS活性相，研究了CoMoS活性相的数量、种类和催化活性与MoS2形貌的关系，发现CoMoS更容易在MoS2的S边位上产生，通过调控MoS2的形貌使其暴露更多的S边位有利于CoMoS活性相的形成，从而提高催化剂的催化性能。本项目研究揭示了MoS2形貌与CoMo基催化剂加氢脱硫和水气变换制氢等性能之间的构效关系，对于指导高性能CoMo基催化剂的设计和开发具有重要的理论意义。