Regulating the mobility of lattice oxygen on hollow cobalt-manganese sub-nanospheres for enhanced catalytic oxidation of toluene and o-xylene.

Promoting lattice oxygen mobility of Co-based catalysts is crucial to making progress in catalytic oxidation technology. The addition of manganese, a transition metal with similar ionic radius to cobalt and variable valence, was supposed to enhance the mobility of lattice oxygen species of Co-based oxide. A range of hollow CoMnO sub-nanosphere catalysts with different Mn/Co ratios was synthesized via a template-sacrificed method, and the effects of different Mn/Co ratios on the structural properties of the catalysts and their catalytic performance for benzene series volatile organic compounds (VOCs) oxidation were investigated. Hollow CoMnO sub-nanosphere exhibited good catalytic activity for oxidation of toluene (T = 265 °C) and o-xylene (T = 297 °C), as well as excellent recycling ability and water resistance. By adjusting the Mn/Co ratio, metal ions enter into the different tetrahedral or octahedral active sites. Compared with CoO, the desorption temperature of surface lattice oxygen on CoMnO decreased by 110 °C. These results demonstrate that the addition of manganese can encourage the electron transfer on CoMnO, indicating that the introduction of the appropriate amount of manganese accelerates the activation of gas O and mobility of surface lattice oxygen species, thereby expediting the oxidation of benzene series VOCs.