Green synthesis of cavity-containing manganese oxides with superior catalytic performance in toluene oxidation

Abstract

Manganese oxide prepared by a simple hydrothermal method is highly active and stable in both lab and quasi industrial conditions for the total oxidation of toluene, achieving total conversion at only 175 °C in the absence of water and at 150 °C in the presence of 4 mol % water. Moreover, this performance is stable for at least 6 cycles. The enhanced catalytic performance has been related to the presence of highly reactive oxygen surface species. This species are probably promoted by Mn3O4 nanoparticles with Mn3+ at the tetragonal distorted cationic sites, likely compensated by structural water at the anionic sites. The presence of structural water can be related to the formation of internal cavities/vesicles in the Mn3O4 crystalline structure.