摘要/Abstract
稀土在中国储量丰富，尤其在徐光宪等老一辈科学家不懈努力下开发了高效提纯稀土元素的有效方法，为当今的稀土性能应用研究打下了坚实的基础.稀土包括钪、钇以及镧系金属在内的17种元素，由于镧系元素最外层电子和次外层电子的结构相似（[Xe]4fn-15d0～16s2（n=1～15）），尤其是其独特的4f电子层结构，使稀土元素具有化学性质稳定、化学价态可变、配位形式多样、总体具有Lewis酸性等特点，使其在催化领域具有广泛的应用.但稀土元素电子层结构与催化反应效果之间的关系尚未有明确的总结，因此本文从稀土材料的电子结构特点出发，综述了其在多相（热）催化领域中作为载体、Lewis酸（碱）中心以及催化助剂等方面的应用.
关键词: 稀土材料, 载体, Lewis酸(碱), 催化助剂
Rare earth (RE) resources are in big amount in China, which can be effectively purified based on the strategies developed by Prof. Guangxian Xu et al. last century, which sets up solid fundamentals for applied research on rare earth materials nowadays. Rare earth elements, including scandium, yttrium and lanthanides, feature stable overall chemical properties, variable valence states and coordination form as well as special Lewis acidity due to the unique electron configuration in the outermost and secondary outer orbitals of the lanthanide elements ([Xe] 4fn-15d0~16s2 (n=1~15)), especially on their 4f electron shell structure, having been extensively used in catalysis. However, the efficiency and selectivity to the desired products are always the major challenges due to the complexity of catalysis, in particular, the mechanism by which rare earth metals affect catalytic reactions through structural or electronic effects has not been clarified. Therefore, this mini-review summarizes the research progress on the application of rare earth materials in heterogeneous catalysis (specifically on thermal catalysis). Firstly, a brief summary of rare earth materials' structural properties is provided with emphasis on the unique distribution of the 4f electron. Afterward, the application of RE elements in thermal catalysis was discussed in detail. For example:(1) as a support to promote catalytic reaction, such as CeO2, which has variable chemical valence and can be used as an active support to participate in the redox reaction; (2) as moderate Lewis acid (base) center to catalyze the aldol condensation of acetaldehyde/ethanol mixture and effectively control the C-C bond coupling; (3) as electronic and structural promoters to improve catalytic activity and stability. Hence, the structure-function relationship is illustrated in accordance with the studies of the rare earth materials as the supports, Lewis acid (base) active center and catalytic promoters, suggesting great potential of rare earth materials in catalysis.
Key words: rare earth material, support, Lewis acid (base), catalytic promoters
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