Morphological and catalytic stability of mesoporous peony-like ceria

Mesoporous peony-like ceria has been previously investigated to exhibit superior catalytic properties for CO oxidation, ethanol reforming and anode catalysts for low temperature SOFC. In this work, morphological and catalytic stability are investigated upon heat treatments in reducing and oxidizing atmosphere at temperatures between 300 and 600 °C. Although the peony-like appearance remains stable upon heat treatment at 600 °C for up to 72 h, the BET surface area decreases from 150 to 30 m2g−1 with nanocrystalline size increased from 6 to 15 nm. Catalytic activity of CO oxidation decreases such that T50 (temperature for 50% conversion) increases from 153 to 197 °C. Although morphological variation is more prominent significant upon treatment in reducing atmosphere, the catalytic activity for CO oxidation degrades less than in oxidizing atmosphere. Oxygen vacancies produced upon reduction treatment are responsible for the superior catalytic activity despite the morphological disadvantage.

When CeO2 is calcinated in reducing atmosphere, there are more oxygen vacancies generated near the surface, which are the active sites for oxygen activation and can promote the mobility of oxygen. The generated oxygen vacancies in reducing atmosphere can explain the poorer stability and higher activity for CO oxidation of the peony-like CeO2 calcinated in H2 than in the air.Figure optionsDownload as PowerPoint slideResearch highlights
► Hierarchical peony-like nanostructured mesoporous ceria.
► Structure and catalytic stability from 300 to 600 °C under both reducing and oxidation atmosphere.
► Superior catalytic activity towards CO oxidation.