Investigation on plasma-driven methane dry reforming in a self-triggered spark reactor

The performance of methane dry reforming in a self-triggered spark discharge reactor is evaluated in terms of conversion of reagents, yield and selectivity of desired products (syngas), and energy efficiency. The effects of feed gas composition (CO2:CH4 ratio), flow rate and input electrical power were investigated. The process performance is very good: under the best experimental conditions (CO2: CH4 of 1: 1 at 100 mL . min(-1), input power of 20 W) conversion (71% for CH4 and 65% for CO2), selectivity (78% for H-2 and 86% for CO), and energy efficiency (2.3-2.4 mmol . kJ(-1)) are all quite high. The formation of ethane, ethylene, and acetylene was also detected and analyzed as a function of the CO2: CH4 ratio. As the CO2: CH4 ratio is decreased below 1, the conversion of both CH4 and CO2 slightly increases, but the yield in syngas decreases favoring the formation of C-2 hydrocarbons and the appearance of carbon deposits. Increasing the CO2: CH4 ratio from 0.5 to 1.5 has virtually no effect on the reagents conversion and on H-2 production but promotes the formation of CO and reduces that of C-2 hydrocarbons. The best CO2: CH4 was determined to be 1.0 considering also the lowest formation of water as byproduct and the optimal discharge stability.