Catalytic ozone oxidation toluene over supported manganese cobalt composite: influence of catalyst support

In this study, the manganese cobalt composite (Mn-Co)-loaded SiO₂, MgO, TiO₂, γ-Al₂O₃ and silicalite-1 were prepared by ultrasonic complexation method. The catalysts were characterized by XRD, BET, SEM, TEM, H₂-TPR and XPS, and the activity of catalytic oxidation of toluene was evaluated. It was found that Mn-Co loaded γ-Al₂O₃ (Mn₂CoO_x/γ-Al₂O₃) exhibited excellent catalytic activity. When the gas hour space velocity (GHSV) was 45,000 h⁻¹, the removal rate of toluene reached 91.2% within 5.5 h, and the selectivity of CO₂ was 71.10% at ambient temperature. The operation of Mn₂CoO_x/γ-Al₂O₃ at different temperatures was investigated, and the better toluene removal efficiency more than 80% after reacting 9h was obtained at 50 °C. The characterization results showed that better catalytic activity is related to smaller grain size, higher Mn³⁺/Mn⁴⁺ values and the relative content of active oxygen species (O_II + O_III). Increased amounts of low state species easily led to the imbalance of the catalyst surface charge and promoted the formation of more oxygen vacancies.