The structural evolution of MnOx with calcination temperature and their catalytic performance for propane total oxidation

Manganese oxide is one of the most active transition oxides catalysts and widely applied in various reactions due to its structure diversity. Especially in VOCs oxidation, it usually exhibited excellent performance. The systematic study on structure evolution with catalytic performance is rare. Here, we prepared a series of MnOx by calcinating 8-MnO2 at different temperatures, and investigated their catalytic performance for propane total oxidation. Both of the crystalline phase and morphology presented obvious changes as the calcination temperature elevation from room temperature to 900 degrees C. It changed from 8-MnO2 to alpha-MnO2 and then Mn2O3 with the morphology from sphere-like gradually to nanoplates and/or nanorods. The activation capacity of alpha-MnO2 is proved to be slightly better than 8-MnO2 and much better than Mn2O3 for propane total oxidation. Abundant subsurface lattice oxygen in alpha-MnO2 facilitated propane total oxidation to react more easily, while better reducibility contributed more to the comparable activity of 8-MnO2, and to the slightly lower activity of Mn2O3. The present research will gain deep insight on the structure and application of Mn-based materials in VOCs removal.