Hydrogen production from decomposition of ethanol using a non-self-sustained plasma discharge at atmospheric pressure: Hydrogen selectivity and energy efficiency evaluation

Today, hydrogen stands out as one of the most strategically important substitutes for carbon-based fuels, offering numerous advantages. These include a reduction in reliance on finite reserves of fossil fuels, mitigation of the greenhouse effect by minimizing CO2 emissions, and the release of more energy during combustion compared to traditional fuels. However, over 95% of the current hydrogen production stems from fossil fuels, predominantly through steam methane reforming (SMR), an energy-intensive process that generates substantial quantities of CO2. Hence, there's a growing interest in exploring alternative techniques, such as leveraging plasma sources. Non-thermal plasmas (NTPs) have emerged as a promising avenue for hydrogen production through the decomposition of hydrocarbons, alcohols, and various polymers, given their CO2 neutrality and compatibility with renewable energy sources. NTPs can efficiently dissociate almost any H-rich compounds into molecular hydrogen and other valuable products such as C2H6 and CO. Among H-rich feedstocks, ethanol has captured researchers' attention due to its derivation from renewable bio-ethanol obtained from biomass. However, enhancing the conversion efficiency and selectivity of this process remains of importance. Within the realm of NTPs, non-self-sustained plasma discharges, operating at atmospheric pressure, are known to prevent instabilities and create large-volume plasmas crucial for chemical reactions. Nonetheless, they represent a relatively underexplored yet promising frontier for hydrogen generation from ethanol. In the current study, we employ a plasma discharge operated in a non-self-sustained regime for ethanol decomposition into molecular hydrogen. Ethanol in the gas phase is introduced into the discharge and the resulting decomposition products are analyzed using gas chromatography. We investigate the impact of different gas flow rates on the gas vortex inside the reactor. Moreover, we explore ethanol decomposition under various atmospheres such as argon and nitrogen. Our findings reveal complete ethanol decomposition, with hydrogen being the predominant product detected by gas chromatography, alongside other compounds such as CO, CO2, carbon black, CH4, and C2H6. Furthermore, we determine key parameters like energy yield and selectivity across a wide range of experimental conditions.