Pressurization effect on dry reforming of biogas in kilohertz spark-discharge plasma

To produce high-concentration syngas (CO + H2) from biogas, the effect of pressurization on dry reforming of biogas (CH4/CO2 = 60%/40%) in kilohertz spark-discharge plasma was reported for the first time by elevating the pressure from 1 bar to 2 bar. It was found that elevating the pressure could not only increase the reactant conversions, but also reduce energy cost and increase fuel-production efficiency at the same specific energy input (SEI). In particular, pressurization exhibited a significantly positive effect on increasing CO2 conversion and decreasing energy cost for converting CO2. Syngas concentration as high as 83% (H2/CO = 1.4) was achieved with a ratio of the flow rates of product gas (dry basis) to feeding gas, 1.7, at 2 bar and SEI = 753 kJ/mol. The by-product, H2O, was produced with only about 5% of hydrogen-based selectivity in this work. At 2 bar, the effect of SEI was investigated by varying the power and flow rate, respectively. Compared with those at 1 bar, with the increase in SEI, reactants conversion increased fast, energy cost rose slowly and fuel-production efficiency decreased slowly at 2 bar.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pressurization effect on dry reforming of biogas in spark discharge was explored. ► Elevating the pressure could increase reactant conversions and reduce energy cost. ► Syngas concentration as high as 83% was achieved at 2 bar and SEI = 753 kJ/mol.