含铈氧化物储氧材料的合成方法研究进展

Progress in synthesis methods of ceria-based oxygen storage materials for automotive catalysts

含铈氧化物由于其独特的氧化还原性能及较强的储氧能力成为汽车尾气催化净化三效催化剂的关键材料。气相合成法中的气相凝结法和溅射法是制备具有低起燃温度和无团聚的纳米级非化学计量比催化材料最有效的方法;液相化学法有共沉淀法、溶胶-凝胶法、水(溶剂)热法、微乳液法、溶液燃烧法和溶液聚合配合法等,其中共沉淀法是湿化学过程通用的方法,溶胶-凝胶法能在低温条件下合成出均相多组分复合材料,水(溶剂)热晶化法是合成特定纳米晶体催化材料的最好方法;固相法中的高能球磨法可实现多组分的均匀混合,形成高浓度晶格缺陷的固溶体。综述了含铈储氧材料的气-固、液-固和固-固三大类合成技术的进展,探讨了制备方法和材料特性的关系。

Materials containing ceria are used in three-way catalytic converters because of their unique redox properties and high oxygen storage capacity. The gas-state method such as gas condensation or sputtering is an effective one to prepare nonstoichiometric cerium oxide-based catalysts, which is of lower light-off temperature. The liquid-state method includes coprecipitation, sol-gel, hydrothermal or solvothermal synthesis, coprecipitation, solution-combustion, polymer complex solution, etc. Among which, the chemical coprecipitation is a widely used method of wet process for synthesizing solid materials from solution, the sol-gel method is especially suited for the synthesis and preparation of ultrafine oxide materials at relatively low temperature, and the hydrothermal crystallization is the most popular technique in preparing ceria-based nanoparticles. Mechanical milling is a suitable method for powder preparation, the feature of this procedure is such as to obtain a solid solution with a high concentration of lattice defects. In this paper, conventional processes and recent advances in the synthesis of ceria-based materials are reviewed with the dependence of the methods on reactant and synthetic, for instance gas to solid, liquid to solid and solid to solid, also the methods and characteristics of the materials are discussed.