Optimized mixed reforming of biogas with O2 addition in spark-discharge plasma

Adding O2 into biogas to achieve partial oxidation and CO2 mixed reforming can not only increase H2 + CO concentration, but also reduce energy cost for H2 production. In this study, optimized mixed reforming of biogas with O2 addition in spark-discharge plasma was pursued in combination with thermodynamic-equilibrium calculation. With respect to mixed reforming of biogas with O2 addition in spark-discharge plasma, combination coefficients of independent reactions were given to quantitatively evaluate the mixed extent at various O2/(CH4–CO2) ratios. Compared thermodynamic-equilibrium with experimental results, it can be concluded that the optimal O2/(CH4–CO2) ratio for optimized mixed reforming of biogas in spark-discharge plasma was about 0.7. When total-carbon conversion was relatively high (>75%), H2 + CO concentration on wet basis was the highest and energy cost for H2 production was the lowest at O2/(CH4–CO2) = 0.7, and their experimental results were closest to their thermodynamic-equilibrium values.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Optimized mixed reforming of biogas with O2 addition was pursued. ► The mixed extent of CO2 reforming and partial oxidation was quantitatively evaluated. ► The optimal O2/(CH4–CO2) ratio in spark-discharge plasma was about 0.7.