Impact of methionol concentration on the performance of solid oxide fuel cells directly fueled by liquor

Distilled liquor, consisting mainly of ethanol and water, can be directly utilized as fuel for solid oxide fuel cells (SOFCs), offering a potential solution for portable power generation. Shochu, one of the most popular distilled liquors in Japan with a typical composition of 25 vol% ethanol and 75 vol% water, represents a promising emergency fuel owing to its widespread availability. However, commercial shochu contains volatile organic compounds (VOCs), particularly methionol (C 4 H 10 OS), a sulfur-containing species that poisons reforming catalysts and SOFC anodes, causing severe performance degradation. In this study, nitrogen-doped biochar (BC) was employed as a filtration medium to refine commercial shochu, selectively removing VOCs and reducing the methionol content. Steam reforming of ethanol (SRE) tests conducted using a Ni-loaded hydrotalcite (HT)–dispersed paper-structured catalyst (PSC), denoted as Ni/HT-PSC, revealed higher reforming activity for shochu filtered with nitrogen-doped BC than for both commercial shochu and simulated shochu (an ethanol–water mixture with added methionol). Electrochemical measurements at 750 °C using electrolyte-supported cells (ESCs) with Ni/HT-PSCs demonstrated that an increase in the methionol concentration in the fuel leads to a decrease in the open-circuit voltage ( OCV ) and hinders the surface diffusion processes due to sulfur poisoning. These findings provide the first direct evidence that methionol removal is essential for enabling stable SOFC operation directly fueled by distilled liquor.