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

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.