Hydrogen production from ethanol by a vortex-stabilised non-self-sustained plasma

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Abstract
Non-thermal plasmas offer a catalyst-free route for hydrogen (H2) production. Here, ethanol is decomposed in an atmospheric-pressure, vortex-stabilised non-self-sustained discharge, varying flow rate and plasma gas (Ar with N2 or CO2 admixtures). Gas chromatography identifies H2 as the main product, followed by CO and C2 unsaturated hydrocarbons. With 30 vol.% N2, ethanol conversion reaches 100%, H2 yield increases from 12% to 43%, and the H2 production rate rises to 14.6 g H2·mol-1EtOH·kWh-1 (2.75 times higher than Ar). In contrast, 30 vol.% CO2 reduces H2 yield to 4.7% and the production rate to 2.4 g H2·mol-1EtOH·kWh-1, with H2:CO decreasing to 0.05. CFD confirms a strong swirling vortex, and OES shows gas heating from ~2300 K (Ar) to ~3300 K (30% N2) and ~2850 K (30% CO2). Together, vortex-induced confinement and enhanced gas heating are identified as key factors governing ethanol conversion and product selectivity in this non-self-sustained plasma reactor.