Strong interface interaction enriched surface Co3+ cations on Co3O4-LaCoO3 composite catalyst for highly efficient toluene oxidation

Abstract

Interface interaction existed in the multicomponent determines the catalytic performance of composite catalysts. Herein, a Co3O4-LaCoO3 (Co-La) composite catalyst with strong spinel-perovskite interface interaction was successfully synthesized via a one-pot sol-gel method for the catalytic oxidation of toluene. The activity test results showed that the optimal 1Co3O4–4LaCoO3 (1Co-4La) catalyst exhibits much higher catalytic activity (T90 = 215 °C, GHSV = 50,000 h−1) than Co3O4 (T90 = 295 °C), LaCoO3 (T90 = 256 °C) and 1Co3O4/4LaCoO3 (1Co/4La) (prepared by mechanical ball-milling, T90 = 285 °C). Characterizations revealed that the strong spinel-perovskite interface interaction generated between the Co3O4 spinel and LaCoO3 perovskite in 1Co-4La facilitates the transfer of interfacial electrons, contributing to the exposure of surface active Co3+ and the enhanced oxidation ability of surface active Co3+ on 1Co-4La. In addition, the reactive lattice oxygen of surface Co3+–O on 1Co-4La effectively promotes the decomposition of toluene into CO2, enabling the low-temperature oxidation of toluene through the Mars-van Krevelen (MvK) mechanism. This work provides insight into the promotional effect of multicomponent interface interaction on enhancing catalytic performance of spinel-perovskite composite catalysts.