锌掺杂对铂/碳化钼催化剂的影响机制及催化甲醇水蒸气重整制氢作用机理研究

The fuel cell powered by hydrogen from methanol steam reforming is an efficient solution for in-situ hydrogen supply in its working process. However, the development of a new and highly efficient catalyst for hydrogen production by methanol steam reforming is one of the core issues to be settled urgently in the hydrogen generation system for fuel cells. For this reason, the exploitation of methanol steam reforming catalyst with high activity is the main purpose of this proposal and the Zn-doped Pt/Mo2C catalysts are prepared by different kinds of methods. More focus is being placed on the catalytic activity of Pt/Mo2C catalysts with and without the addition of Zn, the influence mechanism of Zn-doping on Pt/Mo2C catalyst and the structure−activity relationship of Zn-doped Pt/Mo2C catalysts for hydrogen production by methanol steam reforming. Additionally, various characterization methods, experimental techniques and density functional theory (DFT) calculations are carried out to investigate the role of Zn-doped Pt/Mo2C catalysts on the surface reactions such as methanol cracking and steam activation, which reveals the essential characteristics of catalyst active sites on methanol cracking, steam activation and hydrogen production. Together with the surface reactions investigation, the mechanism of hydrogen production by methanol steam reforming on Zn-doped Pt/Mo2C catalysts has been thoroughly studied, which can provide a scientific foundation for the designing of high active catalysts on hydrogen production by methanol steam reforming.

甲醇水蒸气重整制取氢气供给燃料电池发电可以有效解决其工作过程原位供氢的难题。然而，对于燃料电池原位供氢系统，现阶段最亟需解决的核心问题之一是如何开发新型高效的甲醇水蒸气重整制氢催化剂。因此，本项目以研制具有较高活性的甲醇水蒸气重整制氢催化剂作为主要导向，拟采用多种方法调控制备得到锌掺杂铂/碳化钼催化剂，重点研究锌掺杂前后铂/碳化钼催化剂的甲醇水蒸气重整制氢活性变化、锌掺杂对铂/碳化钼催化剂的影响机制及其构效关系。同时，拟通过多种表征手段、实验技术以及DFT计算探究锌掺杂铂/碳化钼催化剂在甲醇分子断键与水蒸气活化等表面反应过程的作用，揭示甲醇分子断键、水蒸气活化以及氢气生成的活性位本质特征，深化认识锌掺杂铂/碳化钼催化剂结构对甲醇水蒸气重整制氢的作用机理，为高效甲醇水蒸气重整制氢催化剂的设计提供基础科学信息。

甲醇水蒸气重整制取氢气供给燃料电池发电可以有效解决其工作过程原位供氢的难题。然而，对于燃料电池原位供氢系统，现阶段最亟需解决的核心问题之一是如何开发新型高效的甲醇水蒸气重整制氢催化剂。因此，本项目以研制具有较高活性的甲醇水蒸气重整制氢催化剂作为主要导向，从以下几方面开展深入研究：（1）获得不同Zn金属含量调控Pt/MoC催化剂结构特征变化间的关系，明确Zn金属调控对Pt/MoC催化剂的影响机制，建立清晰的Zn金属掺杂Pt/MoC催化剂结构与甲醇水蒸气重整制氢性能关系。（2）获取Zn金属掺杂Pt/MoC催化剂在甲醇分子断键与水蒸气活化等表面反应过程的作用，揭示反应过程中甲醇分子断键、水蒸气活化以及氢气生成的活性位本质特征。（3）掌握制氢反应过程中不同方法调控制备得到的Zn金属掺杂Pt/MoC催化剂表面中间物种与反应产物变化规律，探清Zn金属掺杂Pt/MoC催化剂结构对甲醇水蒸气重整制氢的作用机理。. 通过研究发现，添加适量Zn金属修饰Pt/MoC，可以提高其比表面积、孔体积、Pt分散度、Zn与Pt、Mo物种间的相互作用，抑制Pt颗粒的增长和团聚，促进α-MoC1-x晶相的产生，因此Zn掺杂Pt/MoC催化剂可以获得较高的制氢性能。其中，制备的0.5Zn-Pt/MoC催化剂在120 ℃的反应条件下，Zn掺杂Pt/MoC催化剂的催化活性在25 h内保持稳定；在反应温度为160 ℃时，Zn掺杂Pt/MoC催化剂的平均TOF达到1098 molH2•molPt−1•h−1；该催化剂催化性能远优于文献报道的其他MoC基催化剂的甲醇重整制氢活性。此外，通过程序升温脱附、程序升温表面反应以及同位素示踪反应研究发现，甲醇分子脱氢断键与甲氧基脱氢分别可以在α-MoC1-x晶相与Pt活性位上进行，但形成的甲醛物种要想与甲氧基进一步作用产生HCOOCH3中间物种得在Pt活性位与α-MoC1-x晶相的间隙界面上进行；Zn-Pt/MoC催化剂上甲醇水蒸气重整制氢的反应机理遵循以甲酸甲酯为中间物种的路径。. 本项目研究可为高效甲醇水蒸气重整制氢催化剂的设计提供基础科学信息,同时也为解决甲醇水蒸气重整制取氢气供给燃料电池发电过程涉及原位供氢的难题提供了参考和潜在的可行方案。