Renewable and high-concentration syngas production from oxidative reforming of simulated biogas with low energy cost in a plasma shade

• A novel plasma shade for oxidative reforming of biogas was reported.
• Large reactive space formed by rotating spark channels was achieved.
• Increase in conversions with SEI exhibited rapid and slow zones.
• V-shape profile of syngas energy cost versus SEI was observed.
• The optimal SEI was found for concentration and energy cost of syngas.

A novel plasma shade with large reactive space generated by rotating spark channels was used for the first time for oxidative reforming of simulated biogas (CH4:CO2:O2 = 3:2:2) to produce high-concentration syngas (CO + H2) with low energy cost. This unique plasma exhibited rapid- and slow-zones where the conversion of O2, CH4 and CO2 and dry-basis concentration of syngas (CCO+H2dry) changed at two significantly different paces with specific energy input (SEI). With increasing SEI  , the conversion and CCO+H2dry first increased rapidly at SEI < 84 kJ/mol, while the conversion and CCO+H2dry increased at a much slower pace at SEI > 84 kJ/mol. Moreover, V-shape profile of syngas energy cost (ECCO+H2ECCO+H2) versus SEI was observed. Thereby, the optimal SEI   was found at which the lowest ECCO+H2ECCO+H2 (1.0 eV/molecule) and a very high CCO+H2dry (73%) were simultaneously achieved. The good stability of the plasma reaction at the optimal SEI was verified over an 8-hour test.

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