Influence of the pore structure of CeO2 supports on the surface texture and catalytic activity for CO oxidation

Abstract

In this paper, three kinds of CeO₂ nano-materials with different pore structures, i.e., mesoporous, microporous and nanoparticle CeO₂, were synthesized. Mesoporous CeO₂ (meso-CeO₂) and microporous CeO₂ (micro-CeO₂) were prepared by adopting the mesoporous silica KIT-6 and microporous high silica ZSM-5 (Si/Al = 344.1) as templates, respectively. CeO₂ nanoparticles (nano-CeO₂) were synthesized by precipitation method. The palladium loaded meso-CeO₂, micro-CeO₂ and nano-CeO₂ supports were evaluated for their catalytic activity in the CO oxidation reaction. The Pd/meso-CeO₂ exhibited the highest catalytic activity, and the complete conversion temperature (T₁₀₀) was about 50 °C for the CO oxidation. According to the analysis, the meso-CeO₂ support has a mesoporous structure, large BET surface area and small particle size. At the same time, the Pd/meso-CeO₂ catalyst has a large number of active surface oxygen species, Ce³⁺ cationic species and Pd⁴⁺ cationic species. These above characteristics of Pd/meso-CeO₂ were relatively conducive to the catalytic oxidation of CO.