Catalytic combustion of toluene performance over MnOx catalysts: Effect of KMnO4 content

MnOx samples were prepared and applied to the catalytic combustion of toluene. The results indicated that the KMnO4 content was important to the catalytic performance. Cat‐0.2 (0.2 g KMnO4) possessed the best catalytic performance, and more than 90% of toluene conversion was 255°C. Moderate amounts of KMnO4 facilitated the generation of mixed crystalline phases and structural defects, which led to the generation of more oxygen vacancies. In addition, the Cat‐0.2 possessed high contents of Oads/(Oads + Olatt) and Mn3+/(Mn3+ + Mn4+), which promoted the emergence‐annihilation cycle of oxygen vacancies and facilitated the reaction process of toluene. The reaction pathway of toluene was investigated via in situ DRIFTS, in which the by‐products included benzyl alcohol, benzaldehyde, benzoate, maleic anhydride, and short‐chain carbonate. Among them, benzoate was the main intermediate in the catalytic oxidation process of toluene. MnOx with different KMnO4 contents was synthesized by a simple hydrothermal method. The appearance of mixed phases, multiple structural defects, and higher Mn3+/(Mn3+ + Mn4+) and Olatt/(Oads + Olatt) concentrations promoted the emergence‐annihilation cycle of oxygen vacancies, which facilitated the catalytic combustion reaction of toluene. The reaction pathway was investigated using the in situ DRIFT method, which the benzoic acid was main intermediate of toluene degradation.