Catalytic performance of La–Ce–O mixed oxide for combustion of methane

• Published in: Catalysis today Vol. 158; no. 3; pp. 348 - 353
• Main Authors: Zhang, Bo, Li, Dao, Wang, Xingyi
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 22.12.2010; Elsevier
• Subjects: Catalysis; Catalytic combustion; Ceria; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Lanthanum; Methane; Solid solution; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Methane; Catalytic combustion; Lanthanum; Solid solution; Ceria; Binary compound; Fluorite; Reducibility; Cerium oxide; Sustainable development; Lanthanide compound; Chemical reduction; Oxidation; Structure; Mixed catalyst; Composition; Oxygen; Catalytic reaction; Vacancy; Crystals; Ions; X ray diffraction; Heterogeneous catalysis; Sol gel process; Environmental protection
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2010.04.019

A series of Ce–La–O mixed oxide catalysts with different compositions have been prepared by sol–gel method and characterized by XRD, BET, Raman, TPR and CO 2-TPD techniques. The activity of Ce–La–O catalysts for methane oxidation has been investigated. When the ratio of Ce/Ce + La is changed from 1.0 to 0.2, only cubic phase CeO 2 with fluorite structure is observed, whose crystal size decreases significantly with the increase in La amount, due to the formation of LaCeO x solid solution. The peak at 533 °C on TPR profiles of Ce–La–O with fluorite structure is ascribed to the reduction of non-stoichiometric CeO 2− x . Raman bands around 570 and 1167 cm −1 for samples with the Ce/Ce + La ratios of 1–0.2 might be assigned to oxygen vacancies and surface superoxide ions, respectively. The addition of La promotes the formation of non-stoichiometric CeO 2− x , which is responsible for the oxygen vacancies and surface superoxide ions. However, when the ratio of Ce/Ce + La decreases to 0.2, ceria-in-lanthanum solid solutions are formed, where non-stoichiometric CeO 2− x cannot be observed. The high activity of Ce–La–O mixed oxide catalyst for methane combustion is related to superoxide ions and surface reducibility.