稀土氧化物基疏水催化剂的可控制备及其对氢-水同位素交换反应的催化机制研究

Hydrogen-water liquid phase catalytic exchange (LPCE for short) reaction represents a prevailing method for water detritiation worldwide, and the development of efficient hydrophobic catalysts is the key to the implementation of this technology. In the present project, we study the synthesis and the catalytic properties of novel hydrophobic catalysts for LPCE, with special focus on the correlation between composition, microstructure, and catalytic properties，and the catalytic mechanism on promoting the LPCE reaction as well. In this regard, a new type of hydrophobic catalysts, i.e., Pt(PtxMy)/REOs/PTFE (REOs is an acronym of Rare-earth oxides, M=Fe, Co, Ni, et al.), with well-defined composition and microstructure, will be synthesized. To this end, composition-and-shape-controlled synthesis of both nanostructured REOs and Pt or PtxMy nanoparticles will be conducted in our lab by using well-established synthetic approaches. Through systematically study of the effects of a set of compositional or microstructural variables on the catalytic properties individually, it is likely to unravel the composition-microstructure-catalytic properties relationship for this type of hydrophobic catalysts and furthermore, their catalytic mechanism on promoting the LPCE reaction. The successful implementation of the present project may lay experimental/theoretical foundation for the development of high-performance hydrophobic catalysts, and may also provide valuable insight into the design of other kinds of catalysts.

氢-水氢同位素液相催化交换反应（简记为氢-水LPCE反应）是实现水去氚化的重要技术途径，而高效疏水催化剂的研制是其关键环节。本项目选取水去氚化用疏水催化剂为研究对象，重点围绕揭示其成分-微观结构-催化性能间内在关联性及对氢-水LPCE反应的催化作用机制这一关键基础科学问题开展研究。拟采用较成熟的方法合成具有不同成分和微观结构的稀土氧化物（REOs）纳米材料兼作载体和助催化剂、Pt或PtxMy（M=Fe、Co、Ni等）纳米粒子作为活性金属，构筑成分和微观结构受控制备的Pt(PtxMy)/REOs/PTFE型疏水催化剂。在此基础上，系统研究稀土氧化物载体及活性金属的成分、微观结构等因素对氢-水LPCE反应的影响规律，揭示催化剂成分-微观结构-催化性能间的内在关联性并探讨其催化作用机制。本项目预期研究成果将为发展高性能疏水催化剂奠定实验/理论基础，同时也可为其他类型催化剂的研制提供参考或借鉴。

核能的利用涉及产生大量含氚废水，不论是从环境保护还是从稀贵氚资源回收的角度考虑，均需进行水去氚化处理。氢-水同位素液相催化交换（LPCE）技术是实现水去氚化的重要技术途径，而该技术的关键环节则是发展经济高效的疏水催化剂。本项目围绕稀土氧化物基疏水催化剂的可控制备及其对氢-水同位素交换反应的催化性能与机制开展研究，制备出了Pt/REOs/PTFE（REOs是稀土氧化物英文Rare-Earth Oxides的缩写，在本项目研究中主要涉及CeO2、Pr4O7、Sm2O3、Eu2O3等）、Pt/C/CeO2/PTFE、Pt/c-CeO2 (or r-CeO2)/PTFE及PtRux/CeO2/PTFE等数种具有优异疏水性能的稀土氧化物基疏水催化剂。催化性能测试表明，这些稀土氧化物基催化剂的贵金属铂利用效率相较于传统Pt/C/PTFE 型疏水催化剂提升了60%以上，具有更优异的经济性。同时，部分稀土氧化物基疏水催化剂亦显示出较Pt/C/PTFE 型疏水催化剂更强的抗水蒸气毒化能力，因此有望在LPCE的高湿度服役环境下具备更好的耐久性。通过系统研究揭示，稀土氧化物基疏水催化剂的载体及活性金属均对催化性能有重要影响。特别是，稀土氧化物可促进水分子吸附离解和/或调控负载金属化学态的能力很可能是导致稀土氧化物基疏水催化剂对氢-水同位素交换反应的催化性能优于Pt/C/PTFE 型疏水催化剂的重要机制原因。本项目研究拓展了稀土氧化物的催化应用领域，深化了相关催化作用机制认识，可为其他高效催化剂的设计制备提供有益的参考或借鉴。