Boosting catalytic toluene combustion over Mn doped Co3O4 spinel catalysts: Improved mobility of surface oxygen due to formation of Mn-O-Co bonds

Catalytic combustion is considered as the most promising technology for removing VOCs over composite metal oxide catalysts. Herein, Mn doped Co3O4 spinet catalysts (MnaCo1-aOx) like spherical were successfully prepared via solvothermal method, and applied for catalytic toluene combustion. The physical and chemical properties of catalysts were analyzed by various characterization techniques such as XRD, N-2 physical-adsorption, SEM, TEM, H-2-TPR, O-2-TPD, XPS and in-situ DRIFTS. Among these catalysts, Mn0.4Co0.6Ox shows optimal catalytic activity (T-50 = 206 degrees C; T-90 = 215 degrees C) and stability, and it can still maintain good activity even in presence of H2O. The amounts of the surface Co2+, Mn(4+ )and lattice oxygen are improved based on the interaction between Co and Mn ions (Mn3+ + Co3+ -> Mn4+ + Co2+), leading to far stronger oxidation ability of catalyst. The formation of the surface Mn-O-Co bonds on spinet catalysts MnaCo1-aOx improves the mobility of surface oxygen. In addition, the catalytic combustion of toluene over these catalysts follows the Mars-van Krevelen mechanism and the surface lattice oxygen plays a crucial role in the cycle of oxygen species based on in-situ DRIFTS results.