Pathways of hydrogen-rich gas produced by microwave discharge in ethanol-water mixtures.

The ethanol decomposition process for hydrogen-rich gas synthesis via microwave discharge in ethanol-water mixtures was investigated in this study. Excited active species and gas-phase products based on ethanol's varying volume fraction were detected via optical emission spectroscopy (OES) and mass spectrometry (MS). The correlation between the spectrum signal of the active species and the mass spectrum signal of the gas phase products was quantitatively analyzed. The experimental results showed that the intermediate active species mainly consisted of OH, C 2 , CH 2 , CH, C, and H, and the gas phase products mainly included H 2 , CH 4 , C 2 H 2 , CO, C 2 H 4 , and CO 2. There were significantly positive linear relationships between H or CH 2 and H 2 , demonstrating that both H and CH 2 were important radicals for generating H 2. Based on the experimental results and analyzed from the perspective of thermodynamics, the reactions of H + H (+M) → H 2 (+M) and H + H + H 2 →H 2 + H 2 , H + H + H 2 O → H 2 + H 2 O, CH 2 + CH 2 → H 2 + C 2 H 2 were all likely to produce hydrogen. • There were significantly positive linear relationships between H or CH 2 and H 2. • H and CH 2 were important radicals for generating H 2. • Possible reaction path of microwave discharge in ethanol solution was given. [ABSTRACT FROM AUTHOR]