Dry reforming of CH₄ with CO₂ to generate syngas by combined plasma catalysis

The hybrid plasma catalysis system was investigated for dry reforming of methane (DRM) with CO₂ to form syngas. First, dielectric barrier discharge (DBD) alone was evaluated for the effectiveness in conversion of CO₂ and CH₄, and with the applied voltage of 15.0-19.5 kV, and frequency of 200 Hz. The ratio of feeding gas (CH₄/CO₂) and total gas flow rate were controlled at 1 and 40 mL/min, respectively. The results indicate that conversions of CO₂ and CH₄ significantly increase with increasing applied voltage. The conversion of both greenhouse gases (CO₂ and CH₄) achieved the maximum value of 18.9% and 24.0%, respectively, at applied voltage of 19.5 kV. Selectivity of CO decreases from 53.6% to 42.4% as applied voltage is increased from 15.0 to 19.5 kV, while selectivity of H₂ increases from 30.1% to 35.8%. In addition, the influences of gas flow rate and ratio of feeding gas were also explored for DBD-alone system, and the results indicate that energy efficiency of syngas generation can be significantly increased as the flow rate is increased. As a catalyst with a high dielectric constant is placed into the discharge zone, the conversions of two gases (CO₂ and CH₄) reach 27.3% and 31.2%, respectively, at applied voltage of 19.5 kV. Selectivity of CO decreases from 59.4% to 49.6% as applied voltage is increased from 15 to 19.5 kV, while selectivity of H₂ increases from 32.0% to 38.3%. In the meantime, energy efficiency of syngas generation is increased by 0.3%. Overall, this paper indicates that combining DBD with a catalyst of high dielectric constant is a viable process for DRM.