Abstract: In order to improve the inefficiency of volatile organic compound (VOCs) combustion processing, Cr₂O₃ nano-particles were prepared by using a hydrothermal synthesis method and subsequently used as carrier to load manganese through impregnation method, leading to the development of a series of Mn/Cr₂O₃ catalysts. The physical and chemical properties of the catalysts were characterized, and the catalytic oxidation performance for toluene was evaluated. The corresponding results indicated that the introduction of MnO_x onto Cr₂O₃ not only instigated the creation of an organized mesoporous structure within the chromium-based support, but also markedly increased the specific surface area. This enhancement facilitated the dispersion of active MnO_x, maintained the stable structure of Mn/Cr₂O₃ catalysts, and resolved the issue of aggregation-induced deactivation of the active components. When Mn content was 20%, Mn/Cr₂O₃ catalyst exhibited the highest activity, and the temperature for the toluene conversion reaching 50%, 90% and 100%, were 210, 229 and 240 ℃, respectively. Moreover, the toluene conversion could be maintained at 100% at 240 ℃ in 50 h stability test. The results demonstrated that by controlling the amount of Mn species incorporated, it was possible to effectively modulate the pore structure of the Mn/Cr₂O₃ catalysts, the interactions between the metal and support and the ability to eliminate coke deposition.

Key words: toluene, catalytic oxidation, chromium-based catalyst, nano chromium oxide