Synthesis of MnOx/Al2O3 Catalyst by Polyol Method and Its Application in Room Temperature Ozonation of Toluene in Air

摘要

MnOx/Al2O3-P catalyst was synthesized by polyol process and evaluated in catalytic ozonation of toluene in air at room temperature. The effects of polyol synthesis temperature and time were optimized using response surface methodology. The performance of the optimized polyol catalyst was compared with a catalyst prepared by the impregnation method (MnOx/Al2O3-I). Polyol catalyst had higher toluene and ozone conversions with less carbon deposition and higher selectivity towards CO2 in the product than the impregnated catalyst. Nearly 80% of toluene was removed using MnOx/Al2O3-P after 120 min of reaction, which is higher than MnOx/Al2O3-I (70%). Characterization studies showed that MnOx/Al2O3-P has smaller manganese particle size, higher dispersion, and higher surface area than MnOx/Al2O3-I. Both catalysts were mostly composed of Mn3+ phase, while MnOx/Al2O3-P had a higher amount of Mn2+. The higher activity of the polyol catalyst is attributed to smaller manganese particle size, higher catalyst surface area, and lower oxidation state of manganese.