Removal of mixed VOCs of benzene, toluene, and xylene by using catalytic corona discharge system

Abstract

Silver (Ag) and Manganese (Mn) catalysts were loaded on TiO₂ and Al₂O₃ supports on quartz wool that were tested for the oxidation of mixed Volatile Organic Compounds (VOCs) of benzene, toluene, and xylene in nonthermal plasma corona discharge. The total feed concentration of VOCs was fixed at 100 ppm. The catalyst located between the pin and plate electrodes with a constant gap distance of 15 mm and the pin and plate plasma reactor had an inside diameter of 9 mm. The outlet stream was analyzed by gas chromatography equipped with TCD and FID detectors. The operating parameters including applied voltage, input frequency, and types of catalysts could affect to the performance of VOCs removal process especially the selectivity for CO₂. For the sole plasma system, the optimum conditions of an applied voltage of 5 kV and an input frequency of 500 Hz provided a relatively high VOCs conversion with the highest CO₂ selectivity. Among all studied catalysts, the 4%Ag/Al₂O₃ catalyst in the pin and plate corona discharge reactor was found to improve the CO₂ selectivity from 59 to 81% while the CO selectivity was reduced from 31.3 to 6.0%. Due to the catalyst provided high surface area for oxidation reaction and also provide the metal oxide on surface which completely reacted with other hydrocarbon and CO molecules could stayed longer in plasma zone that leaded to the opportunity of CO molecules further oxidized with active oxygen in the system become CO₂.