Novel Ordered Mesoporous γ-MnO2 Catalyst for High-Performance Catalytic Oxidation of Toluene and o-Xylene

The main bottleneck in the catalytic removal of volatile organic compounds (VOCs) is the desire to search for a cheap, highly efficient, and durable catalyst. Herein, we developed a facile synthesis of an ordered mesoporous gamma-MnO2 nanostructure (meso-gamma-MnO2) by treating an ordered mesoporous Mn2O, precursor (meso-Mn2O3) with a dilute HNO3 solution, during which the ordered mesoporous framework was well retained. The resultant meso-gamma-MnO2 was born with high specific surface area and rich surface oxygen vacancies, which could greatly improve its number of surface active sites and reactivity of surface oxygen species. Surprisingly, the meso-gamma-MnO2 exhibited significantly enhanced catalytic activities compared to nonporous alpha-MnO2 nanorods and gamma-MnO2 microurchins, achieving T-90 (the temperatures for 90% conversion of toluene or o-xylene) at 219 and 237 degrees C for removing toluene and o-xylene under a WHSV of 40,000 mL-g(-1). h(-1), respectively. Our results provide an effective and facile route to synthesize a highly efficient gamma-MnO2 catalyst for VOC removal.