Plasma reforming and coupling of methane with carbon dioxide using a point-to-point type of reactor have been invested. A feed mixture of CH4 and CO2 could be converted mainly to CO, H2, and C2H2 at atmospheric pressure and without external heating except plasma heating. Under a condition of 200 mL/min of CH4 and CO2 (CH4:CO2 volume ratio, 50:50), a 2.5 mm discharge gap, and a pulse frequency of 10.3 kPPS, CH4 and CO2 conversion, CO and C2H2 selectivities, H2/CO ratio, and (CH4 + CO2) conversion efficiency were 65.9% and 57.8%, 85.9% and 11.3%, 0.99, and 2.4 mmol/kJ, respectively. C2H2 selectivity and H2/CO ratio could be moderated by changing CH4 concentration in the feed mixture. The influence of methane concentration and pulse frequency on product selectivity and plasma energy efficiency was evaluated. A brief economic evaluation of this process was given. The coproduction of acetylene of high value remarkably improved the production of synthesis gas (CO + H2) from carbon dioxide reforming of methane, which could also contribute the emission reduction of global warming gas CO2.

We studied the oxidative coupling and reforming of CH 4 with CO 2 to C 2 H 4 , CO, and H 2 using a pulsed plasma with a pulse frequency ranging from 166 to 3050 PPS. The largest selectivity of C 2 H 4 was 64% with 31% CH 4 conversion and 24% CO 2 conversion at 2920 PPS and 500 °C. Selectivities of CO and H 2 were about 20% and 100%, respectively. Ratios of H 2 to CO and (CO + CO 2 ) were, respectively, 7.1 and 2.5, which are acceptable for methanol production from (CO + H 2 ) and (CO 2 + H 2 ) over a catalyst. The results indicated that the pulsed plasma with a high frequency can promote conversion of CH 4 and CO 2 . The energy efficiency of the pulsed plasma was improved using a high pulse frequency and a high reaction temperature. We suggested that a pulsed plasma with a high pulse frequency is useful for oxidative coupling and reforming of CH 4 with CO 2 in industry.

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