Co-Based Bimetallic Oxide Catalysts with Abundant Vacancy Defects for Enhanced Oxidation of Toluene.

A series of Co–M (M = Mn, Ce, Cu) bimetallic oxide catalysts were prepared by a modified solvent pyroalcoholysis method, and the performance in the catalytic oxidation of toluene was investigated. The experimental results showed that the conversion rate of the as-prepared Co1Cu1 catalyst performed a 50% conversion (T50) and 90% conversion (T90) in toluene oxidation at 211 °C and 241 °C, respectively. A series of the characterization demonstrated that the performance improvement is attributable to the Co1Cu1 catalyst owning high Co3+ concentration (Co3+/Co2+ = 1.14), abundant surface adsorbed oxygen (Oads/O = 67.33%), and excellent low temperature reducibility. Interestingly, these properties promoted the adsorption and deep oxidation of toluene molecules. Concurrently, the XRD and Raman characterizations verified that the spinel structure of Co3O4 is altered by Cu doping, producing high-valence surface active Co species and numerous lattice defects that increased the catalyst's catalytic efficiency. This study showed that creating defect sites by metal doping is a useful strategy for improving Co3O4 spinel's catalytic activity. [ABSTRACT FROM AUTHOR]