Decomposition of Toluene in Coupled Plasma-Catalytic System

Michał Młotek , Bogdan Ulejczyk , Joanna Woroszył , Krzysztof Krawczyk

Abstract

The study of toluene conversion, in a gas such as the one obtained during the pyrolysis of biomass, was conducted at atmospheric pressure in homogeneous and in coupled plasma-catalytic systems. The effects of discharge power, initial concentration of toluene, and the presence of the bed of NiO/Al₂O₃-G-0117 (industrial catalyst for methane water shift) on the conversion of C₇H₈, the composition of the outlet gas, and its calorific value have been investigated. The gas flow rate was 1000 Nl/h and the initial gas composition was CO (0.13), CO₂ (0.12), H₂ (0.25), and N₂ (0.5). The initial toluene concentration was in the range of 2000-4000 ppm. The obtained results show that the conversion of toluene increases with discharge power and the highest one was obtained in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge plasma. The composition of gas changed within the range of a few percent. In the outlet gas acetylene, ethylene and ethane were observed. Trace amounts of toluene were reduced to benzene and formed C3 and C4 hydrocarbons. In an extended process, the reduction of NiO to metallic nickel, methanation reaction of carbon oxides, and an increase of the conversion of toluene were observed. The conversion of toluene in the extended process was 92%. The catalytic activity of G-0117 in a coupled system increased during the study conducted for about 40 min. The use of G-0117 catalyst led to an increase in the calorific value of the outlet gas. In every examined system, it was above the minimal level demanded by engines and turbines. After the process, carbon deposits were present.