MnOx Catalyst with High-Efficiency Degradation Behavior of Toluene: Effect of Cryptomelane

A series of MnOx catalysts were prepared by hydrothermal reaction of different pH values, which proved the important influence of preparation conditions on the structure and performance of the catalysts. The results proved that the cryptomelane MnOx catalyst with a pH of 10 (Cat-2) exhibited the most outstanding performance in catalyzing toluene. The appearance of cryptomelane on Cat-2 would reduce the chemical valence of Mn, which could increase the content of Mn3+ and the amount of oxygen vacancies. With the increase of Mn3+, the Mn-O bond was broken more easily, and then facilitated the mobility oxygen species, causing the promotion of the catalytic activity. Low-valence manganese, high-capacity oxygen vacancies and maximum concentration of lattice oxygen were the most important reasons for the best catalytic activity of Cat-2. According to the results of in-situ DRIFT, benzyl, benzaldehyde, benzoic acid were the main intermediate products, which followed the Mars-van Krevelen mechanism.

Automated summary

A series of MnOx catalysts were prepared by hydrothermal reaction under different pH values, which showed that the preparation conditions had a significant impact on the structure and performance of the catalysts. Among them, the cryptomelane MnOx catalyst with a pH of 10 exhibited the best catalytic performance, attributed to the reduction of Mn chemical valence, increase of Mn3+ content and oxygen vacancies. In-situ DRIFT results revealed the main intermediate products and reaction mechanism during catalysis.