Oxidative removal of ethylene in a multistage plasma reactor in the presence of TiO2

Abstract

A number of techniques for air pollutant removals are available such as adsorption, biofilaration and incineration. However, these techniques require further treatment and/or are energy-intensive leading to high treatment costs. Both plasma and photocatalysis are promising alternatives since these two techniques can be operated at ambient conditions resulting in low energy consumption as compared to the conventional methods. The main objective of this work was to develop a combined plasma and photocatalytic system for VOC removals. A four-stage plasma and photocatalytic reactor system was setup to study the oxidation of ethylene as a model pollutant. An increase in either applied voltage or stage number of plasma reactors enhanced C2H4 conversion and CO2 selectivity which is in contrast with the effects of frequency and feed flow rate. The commercial TiO2 (Degussa P25), sol-gel TiO2, and 1%Pt/sol-gel TiO2 were used as photocatalysts. The presence of all studied photocatalysts increased the C2H4 and O2 conversions as well as CO2 selectivity in the following order: 1%Pt/TiO2>tiO2>Degussa P25. The synergistic effect of photocatalysts presented in the plasma reactor is resulted from the activation of TiO2 by the energy generated from the plasma.