Study Of The Catalytic Removal Of Toluene And Ozone By Alpha-manganese Dioxide With Microwave-heating Mode

With the accelerated process of industrialization, the problem of air pollution has become more and more serious. Volatile organic compounds(VOCs) are the main air pollutants, and their treatment methods have been paid more and more attention. In this paper, toluene was selected as a typical pollutant of VOCs, and the high activity α-Mn O2 was used as catalyst to degrade toluene. Considering the faster heating rate and low consumption of microwave heating mode, we compare the difference of catalytic activity between microwave heating and the conventional resistance furnace heating mode. Finally, the final barrier of purification of VOCs by O3 with α-Mn O2 was established, and the activity of simultaneous removal of toluene and O3 by microwave heating mode was analyzed. The main research contents include:The α-MnO2 catalyst was prepared by hydrothermal method, and the activity evaluation of α-Mn O2 was heated by a single resistance furnace. The activity was also investigated under different reaction conditions. The results showed that α-Mn O2 has a very good effect on the removal of toluene. With the increase of residence time, and the decrease of initial concentration, the removal rate of toluene increased. Humidity had little effect on its activity. When initial concentration of toluene was 150 ppm, O2 was 20%, carrier gas was N2, retention time was 0.1 s, temperature was 300 oC, the removal rate of toluene could reached more than 97%.A microwave heating device was established, and the activity evaluation of α-Mn O2 was carried on by the device. In microwave heating mode, we found the characteristics of faster heating rate and low consumption and it has a synergistic effect for the degradation of toluene. With the increase of residence time and microwave power, and the decrease of initial concentration, the removal rate of toluene increased.Considering the problems exist in the catalytic removal of toluene by O3 with α-Mn O2, such as the incomplete purification of VOCs and the residual of O3. We established the final barrier of purification of VOCs by O3 with α-Mn O2 using quick and low consumption microwave heating mode. The results showed that the method above has a good effect on the simultaneous removal of toluene and O3. With the increase of microwave power and residence time, the decrease of the initial concentration of O3 and toluene, the removal rate of toluene and O3 increased. The O3 can be removed completely if its residence time is not less than 0.05 s. When the initial concentration of toluene was 30 ppm, initial O3 concentration is 40 ppm, residence time is 0.15 s, microwave power is 300 W, the removal rate of toluene can reach above 98%, and ozone can be removed completely.