Regulation of oxygen vacancies in cobalt-cerium oxide catalyst for boosting decontamination of VOCs by catalytic oxidation

Abstract

Herein, we developed a series of self-assembled cobalt-cerium oxides (CoCe-x) with the regulated oxygen vacancies, to enhance the decontamination of air pollution with low-temperature catalytic oxidation, in which the typical volatile organic pollutant (VOCs), toluene, acted as the target. The oxygen vacancies in catalyst was tuned by the efficient incorporation of Co atoms into the lattice structure of ceria, and therefore improved the migration of oxygen species, the formation of surface adsorbed oxygen with high activity, as well as the redox recycles of Co3+/Co2+ and Ce4+/Ce3+. Due to the abundant oxygen vacancies, the CoCe-5 (Co loading of 5 wt%) catalyst exhibited the significantly enhanced performance in the low-temperature catalytic oxidation of toluene, on which the conversion temperature of toluene (T90) shifted to 192 °C, reduced by 23% compared with the ceria. From in situ DRIFT results, the surface adsorbed oxygen and lattice oxygen with high mobility played key roles in the excellent performance of CoCe-5 catalyst, which promoted the adsorption, activation and oxidation of toluene significantly, especially accelerating the rate-determining step of toluene oxidation, the breakage of aromatic ring.