Synergistic oxidation of toluene through bimetal/cordierite monolithic catalysts with ozone

Toluene treatment has received extensive attention, and ozone synergistic catalytic oxidation was thought to be a potential method to degrade VOCs (violate organic compounds) due to its low reaction temperature and high catalytic efficiency. A series of bimetal/Cord monolithic catalysts were prepared by impregnation with cordierite, including Mn_xCu_5-x/Cord, Mn_xCo_5-x/Cord and Cu_xCo_5-x/Cord (x = 1, 2, 3, 4). Analysis of textural properties, structures and morphology characteristics on the prepared catalysts were conducted to evaluate their performance on toluene conversion. Effects of active component ratio, ozone addition and space velocity on the catalytic oxidation of toluene were investigated. Results showed that Mn_xCo_5-x/Cord was the best among the three bimetal catalysts, and toluene conversion and mineralization rates reached 100 and 96% under the condition of Mn₂Co₃/Cord with 3.0 g/m³ O₃ at the space velocity of 12,000 h^-1. Ozone addition in the catalytic oxidation of toluene by Mn_xCo_5-x/Cord could efficiently avoid the 40% reduction of the specific surface area of catalysts, because it could lower the optimal temperature from 300 to 100 °C. (Co/Mn)(Co/Mn)₂O₄ diffraction peaks in XRD spectra indicated all the four Mn_xCo_1-x/Cord catalysts had a spinel structure, and diffraction peak intensity of spinel reached the largest at the ratio of Mn:Co = 2:3. Toluene conversion rate increased with rising ozone concentration because intermediate products generated by toluene degradation might react with excess ozone to generate free radicals like ·OH, which would improve the toluene mineralization rate of Mn₂Co₃/Cord catalyst. This study would provide a theoretical support for its industrial application.