Plasma-enhanced catalysis of propane and isopropyl alcohol at ambient temperature on a MnO2-based catalyst

Abstract

The removal of two volatile organic compounds (propane and isopropyl alcohol) by a nanosecond pulsed corona discharge serially combined with Al2O3–MnO2 catalytic post-treatment has been investigated in air at atmospheric pressure and room temperature. The degradation mechanism of VOCs in the non-thermal plasma is a serious problem: several hazardous organic compounds (acetone and formaldehyde) are produced, and the formation yield of CO is higher than CO2. The high concentration of ozone (up to 800ppm) produced in the corona discharge can be used to further oxidize the VOCs on the catalyst. The efficient decomposition of O3 on MnO2 at ambient temperature leads to the formation of reactive oxygen species susceptible to react with residual pollutants in the effluent. This results in a significant increase of VOCs destruction and removal efficiency. Moreover, the catalytic post-treatment greatly enhances the conversion of propane into CO2. The study of ozone-promoted decomposition mechanism of C3H8 on the catalyst has shown that organic by-products are adsorbed and gradually oxidized on the surface. However, concerning isopropyl alcohol, the oxidation remains incomplete: the formation yield of acetone increases after catalytic post-treatment, and the concentration of carbon oxides remains very low. The treatment of immobilized C3H7OH by ozone could be an alternative technique. Finally, the influence of the gas composition on the decomposition rate of ozone was also investigated.