Effect of Ce2O3 phase transition on the catalytic oxidation for toluene over CeO2 catalysts.

Cerium oxide catalysts with localized Ce 2 O 3 phase transition were prepared by controlling the calcination temperature. The effects of O act at the heterogeneous interfaces of CeO x catalysts and catalytic mechanism were investigated. The oxidation of toluene experienced intermediates of benzyl alcohol, benzaldehyde, benzoate, maleic acid and carbonates. Among them, benzoic acid was the decisive step in the toluene oxidation pathway. [Display omitted] • Simple preparation of CeO 2 catalysts with localised Ce 2 O 3 phase transition. • Influence of heterogeneous interfaces on catalyst properties. • Oxygen species located at the CeO 2 -Ce 2 O 3 heterogeneous interfaces were active sites. • The possible reaction mechanism of toluene was proposed by DRIFT analysis. Cerium oxide was a potential replacement for precious metals as a catalyst for VOCs. Here, we prepared CeO x -350, CeO x -450, CeO x -550 and CeO x -650 catalysts by controlling the calcination temperature, the occurrence of Ce 2 O 3 localized phase transitions at CeO x -350 and CeO x -550 was confirmed by XRD, HRTEM and TGA. This localized phase transition caused the change in specific surface area and crystallinity, and prolonged the Ce-O-Ce bond lengths at the heterogeneous interfaces, enhancing the redox capacity and activity of oxygen species. CeO x -550 exhibited the optimal low-temperature activity towards toluene due to the highest Ce3+ content, oxygen vacancy content and the best activity of reactive oxygen species. The oxidation of toluene experienced intermediates of benzyl alcohol, benzaldehyde, benzoate, maleic acid and carbonates. Among them, benzoic acid was the decisive step in the toluene oxidation pathway. Combined with the reaction pathway of toluene, the reaction stages of different oxygen species were determined. The active oxygen species located at the heterogeneous interface would serve as an adsorption site for toluene. The Ce 2 O 3 phase would participate in the deep oxidation of toluene as an active site, which was equivalent to the oxygen vacancies. This study was conducted to explore the effect of local phase transition on catalytic activity, which provided a new strategy for the synthesis of highly active cerium oxide catalysts. [ABSTRACT FROM AUTHOR]