Synthesis of mesoporous cerium dioxide by the sol-gel process and rheological measurement in ceria gel

Abstract

Ceria is used as a catalyst as well as a catalyst support. To improve the quality of this material, the influence of sol-gel parameters on the final gel structure was explored. In this work porous cerium dioxide was synthesized via the sol-gel process, and the viscoelastic properties of cria gel were investigated. Depending on the hydrochloric acid-to-alkoxide molar ratio and amount of water, the specific surface areas of the cubic phase cerium dioxide varied from 65 to 156 m2/g after calcination in air at 773 K for 1 h. The pore size distribution became smaller with increasing amount of acid. At higher calcination temperaures and longer times, surface area and pore volume of the cerium dioxide decreased, whereas crystallinity increased. Viscoelastic studies using liquid rheology instrument of the ceria gels showed different gelation times depending on different amounts of acid and water. By increasing the amount of water while maintaining the solvent amount constant, this in turn reduced the rate of hydrolysis and condensation, resulting in longer gel times.