Statistical Analysis of Ethane and Propane Production from Greenhouse Gases in a DBD Plasma Reactor Using a Response Surface Methodology

In this study, a non-catalytic process of oxidative coupling of methane (CH₄) and its conversion to ethane and propane in the presence of carbon dioxide (CO₂) was statistically studied. Fifteen experiments were conducted under different conditions, including determination of the CH₄/CO₂ ratio (1.5‒3), the total feed flow rate (22.5‒80 mL/min), argon flow rate (50‒100 mL/min), and voltage (6‒11 kV) under atmospheric conditions. The statistical analysis of the experiments showed that the model applied for evaluating the percentage of CH₄ conversion, Selective Internal Energy (SIE), and the reactor power was valid, and there was a good match between the experimental and predicted results. Based on the results, as the CH₄/CO₂ ratio increased, the selectivity of ethane and propane as well as the energy efficiency (EE) of a system increased, while CH₄ conversion decreased. In addition, increase in the Ar flow rate caused an increase in the CH₄ conversion and selectivity of ethane and propane. Moreover, CH₄ conversion, power, ethane selectivity and SIE increased as the voltage increased, though EE and propane selectivity decreased. Finally, the total feed flow rate caused increase in the CH₄ conversion and ethane selectivity, whereas propane selectivity and EE decreased.