Tuning the structure of Co3O4@MnOx catalyst by in situ redox approach for enhancing activity of the catalytic combustion of toluene

A novel in-situ redox method is proposed to prepare Co3O4 based catalysts with a core-shell-like structure toward the catalytic oxidation of toluene. The results of XRD, SEM and HRTEM reveal that Co3O4@MnOx with a coreshell-like structure was obtained after the precursor was partially oxidized by potassium permanganate. The as-prepared Co3O4@MnOx catalyst exhibits considerably high efficiency for the catalytic combustion of toluene, achieving 90% conversion of toluene at 233 degrees C that is at least 65 degrees C lower than that of the sole Co3O4 sample. The real reason is that Co3O4@MnOx is remarkably active than the other samples was explored by analyzing the results of a series of characterizations including Raman, XPS, TEM and H-2-TPR. The results show that the catalytic activity of the samples is affected by the amount of Co3+ species, the concentration of oxygen species, and the content of oxygen vacancies to some extent, however, the result of H-2-TPR indicates that their reactivity rather than the absolute content is the decisive factor for the activity of these catalysts. In addition, Co3O4@MnOx presents a satisfactory long-term stability, suggesting its great potential in industrial application.