Plasma reforming of toluene as a model tar compound from biomass gasification: effect of CO2 and steam

Abstract

Abstract In this study, plasma reforming of toluene as a tar model compound from biomass gasification has been carried out using an AC gliding arc discharge reactor. The influence of steam and CO 2 addition on the reforming of toluene has been evaluated. The results show that the highest toluene conversion (59.9%) was achieved when adding 3 vol% CO 2 at a toluene concentration of 16.1 g/Nm 3 and a specific energy input of 0.25 kWh/m 3 . Further increasing CO 2 concentration to 12 vol% decreased the conversion of toluene. The presence of steam in the plasma CO 2 reforming of toluene creates oxidative OH radicals which contribute to the enhanced conversion of toluene and energy efficiency of the plasma reforming process through stepwise oxidation of toluene and reaction intermediates. Hydrogen and C 2 H 2 were identified as the major gas products in the plasma reforming of toluene without CO 2 or steam, with a yield of 9.7% and 14.5%, respectively, while syngas was the primary products with a maximum yield of 58.3% (27.5% for H 2 and 30.8% for CO) in the plasma reforming with the addition of 12 vol% CO 2 . The plausible reaction pathways and mechanism in the plasma reforming of toluene have been proposed through the combination of the analysis of gas and condensed products and spectroscopic diagnostics.