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 H2 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 C2 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 H2 production but promotes the formation of CO and reduces that of C2 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.