Effects of surface area and oxygen vacancies on ceria in CO oxidation: Differences and relationships

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2010-02, Vol.316 (1), p.59-64
• Main Authors: Liu, Yi, Wen, Cun, Guo, Yun, Lu, Guanzhong, Wang, Yanqin
• Format: Article
• Language: English
• Subjects: Catalysis; CeO 2; Chemistry; Exact sciences and technology; General and physical chemistry; Lattice oxygen extraction; Mechanism; Oxygen migration; Oxygen vacancies; Rate-determining step; Surface area; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2009.09.022

The key factors and their relationship in CO oxidation were found on CeO 2 by comparing the activities of two kinds of CeO 2 in CO oxidation. Both surface area and surface oxygen vacancies play crucial role in CO oxidation because they influence the rate-determining step—the lattice oxygen extraction. Many properties of ceria, such as surface area, defects, and exposed crystal faces, were found to influence the CO oxidation performance of the ceria. Nevertheless, the relations of these properties, which will facilitate the understanding of the catalytic role of ceria in CO oxidation, have not been studied. In this study, the ceria catalysts, HY and CA, were synthesized by hydrothermal method and citric acid sol–gel method, respectively, and the difference in the CO oxidation performance of them was studied using kinetics analysis. Results of temperature-programmed experiments and pulse experiment indicated the lattice oxygen extraction was the rate-determining step (RDS) in the CO oxidation on HY and CA catalysts. The RDS was influenced predominantly by the amount of the active lattice oxygen and the rate of oxygen migration on the catalyst, which were related to the surface area and oxygen vacancies in the catalyst.