Reaction performance of Non-Thermal plasma induced CO2 reforming of CH4 for landfill gas treatment

Abstract

Non-thermal plasma induced reforming of landfill gas into syngas is an attractive alternative approach to resource recovery from small-scale and variable landfill gas streams. The reaction performance, as indicated by reactant conversion, product yield, and reaction energy intensity, of non-thermal plasma-induced CO₂ reforming of CH₄ has been systematically investigated in a coaxial cylindrical dielectric barrier discharge (DBD) reactor. The reactor surface temperature distribution under varying process parameters is incorporated to investigate its impact on discharge and plasma chemical reaction. It is shown that either an increase in the DBD input power or a reduction in the inlet flow rate leads to greater CH₄ and CO₂ conversions and syngas yield. A higher CO₂ to CH₄ molar ratio improves CH₄ conversion and syngas yield and reduces the generation of C₂ and C₃ hydrocarbons. The CH₄ and CO₂ conversions and H₂ and CO yields reached their maximum values of 44.5 %, 27.4 %, 17.1 %, and 20.2 %, respectively, in this experiment. The O∙ radicals generated during CO₂ splitting are crucial in enhancing CH₄ reforming. The reaction energy intensity, defined as the ratio of the enthalpy change of the desired reactions to the DBD plasma discharge energy, increases effectively with increasing CO₂/CH₄ molar ratio. The response surface methodology (RSM) is employed to explore the interactions among the three key parameters, and the response surface optimization identified optimal conditions of 80 W input power, 80 ml/min inlet flow rate, and a CH₄/CO₂ molar ratio of 1.0:2.5, achieving a reaction energy intensity of 19.3 %.