Metals incorporated into OMS-2 lattice create flexible catalysts with highly efficient activity in VOCs combustion

Abstract

Catalytic combustion of different types of VOCs with various functional groups generally requires certain catalysts with high efficiency. Here, a novel manganese oxide catalyst was tuned via incorporation of small amounts of different metals, including Ce, Ir, Ag, Pd, Cu and Fe respectively, exhibiting flexible activity in the abatement of different VOC species. Pd and Ag doping was beneficial for toluene oxidation, while the addition of Cu significantly enhanced the acetone elimination performance, and Ir incorporation boosted the removal of dichloromethane. XRD, Raman, and TEM results revealed that the different metal ions were well-dispersed into the lattice of OMS-2. Elemental mapping images and ICP-OES combined with DFT calculations demonstrated that Ce, Ir, Pd, Cu and Fe were incorporated into OMS-2 by substituting for Mn on octahedral sites, and Ag could be stabilized in the tunnel of OMS-2 via replacing K ions. EXAFS results suggested that the local tunnel structures of OMS-2 were almost intact after incorporation of the different metals. Pd-OMS-2 and Ag-OMS-2 exhibited excellent activity in catalytic oxidation of toluene due to the improved reducibility and mobility of oxygen. Cu ions improved the scission of CC bonds in acetone and Ir ions facilitated the cleavage of the CCl bond in dichloromethane, all of which contributed to their highly specific activity in removal of the corresponding VOCs. This work provides information on the production of highly efficient metal sites for catalytic oxidation of specific VOC species, and may assist with the design of flexible catalysts for control of miscellaneous VOCs.