Synergistic Effects in Porous Mn–Co Mixed Oxide Nanorods Enhance Catalytic Deep Oxidation of Benzene

Abstract

A series of Mn–Co mixed oxide nanorods with homogeneous worm-like pores were facilely prepared by a sol–gel chelating method. With incorporating Mnⁿ⁺ into Co₃O₄, the formation of solid solution with spinel structure inhibits the growth of nanoparticles which is benefit to keep smaller crystal size and higher surface area. XPS and H₂-TPR results indicate that there are more high manganese valence (Mn³⁺ and Mn⁴⁺) and adsorbed oxygen species as well as low-temperature reducibility for the mixed oxide catalysts, as a result of the strong synergistic effect between Mn and Co species in solid solution, which will play a key role in catalytic activity. The as-prepared catalysts were used for catalytic deep oxidation of benzene which is a typical carcinogenic VOC. The catalytic activities over the mixed oxides with varied mole ratio are much higher than that on the single MnO_x or Co₃O₄. The Mn₅Co₅ sample showed the best activity with T_90% for benzene conversions into CO₂ were low to 237 °C at a high space velocity of 120,000 mL g⁻¹ h⁻¹.

Graphical Abstract