Catalytic abatement of volatile organic compounds assisted by non-thermal plasma: Part II. Optimized catalytic electrode and operating conditions

Catalytic purification of air containing 250 ppm of toluene assisted by non-thermal plasma was carried out with a novel dielectric barrier discharge (DBD) reactor with an inner electrode made of sintered metal fibers (SMF). The optimization of the reactor performance was carried out by modifying the SMF with Mn and Co oxides, varying the voltage from 12.5 to 22.5 kV and the frequency in the range of 200–450 Hz. Under the experimental conditions used, the MnOx/SMF showed better activity than CoOx/SMF and SMF during the total oxidation of toluene. The complete oxidation of 250 ppm of toluene was possible with the MnOx/SMF catalytic electrode at the specific input energy (SIE) of ∼1650 J/l. A higher SIE of ∼2100 J/l was required with CoOx/SMF for the total oxidation of toluene to CO2. The better performance of the MnOx/SMF compared to other catalytic electrodes seems to be related to the formation of short-lived species by the in situ decomposition of ozone. XPS analysis of the solid deposit formed on the electrode surface shows the formation of carbonaceous species containing oxygen and nitrogen groups.