Intensification of plasma process for the decomposition of p-xylene as a tar model compound to minimize the unwanted byproduct formation

In this study, the decomposition of p-xylene is studied in different carrier gases (N₂, H_2, and CO₂) across a range of plasma powers (5 to 40 W). At 5 to 10 W, the decomposition of p-xylene was maximum in N₂ carrier gas, whereas it was minimum in CO₂ carrier gas. However, nearly complete decomposition of p-xylene >98 % occurred in all carrier gases at 20 W. The effect of carrier gases and plasma input power on the decomposition of p-xylene disappears at higher power (20–40 W) due to the maximum decomposition of p-xylene. However, the yield of gaseous products significantly varies at all levels of power and the nature of carrier gas. The yield of H₂ and CO (produced only in CO₂) continuously increases with increasing power (5 to 40 W) in N₂ and CO₂ gases. However, the yield of lower hydrocarbons remains unaffected with power and it was below 2 % in both carrier gases. In H₂ carrier gas, the yield of lower hydrocarbons (LHC) increases significantly to 18.5 % with the increase in power to 40 W. A significant amount of carbon was missing in all carrier gases because of the formation of solid residues (unwanted byproducts). Therefore, the synergistic effect of temperature was studied to investigate the effect on product distribution. It was noted that the LHC’s yield increased to 82 % from 18.5 % with increasing the temperature up to 300 °C in H₂ carrier gas with the maximum yield of CH₄ (58 %). Further, increase in temperature up to 400 °C, the yield of CH₄ increased to 75 %, whereas the total yield remained constant. The effect of temperature on the yield of lower hydrocarbons was not significant in CO₂ and N₂ carrier gas as the maximum yield of lower hydrocarbons reached to only 10 % in N₂ carrier gas.