Low-temperature highly selective Kolbe electrolysis of acetic acid in bio-oil on a stable in situ grown RuO2/TiO2 at industrial-level current

Abstract

Acetic acid (AA) is abundant in biomass pyrolysis oil (bio-oil) but its presence can hinder the use and storage of bio-oil. In this study, we developed a highly stable in situ grown ruthenium dioxide (RuO₂)/titanium dioxide (TiO₂) catalyst for Kolbe electrolysis (KBE) at high current densities, converting AA to ethane (C₂H₆) with an 82% (±5%) selectivity. The RuO₂/TiO₂ catalyst sustained at least 150 hours of KBE at 100 mA cm⁻², converting 3300 mmol of AA into 32.6 L of C₂H₆ with a faradaic efficiency of 74.1%. The selectivity for C₂H₆ remained high even in the presence of model bio-oil-relevant oxygenated phenolics and carbonyl compounds, and real bio-oil produced from corncob pyrolysis (88% selectivity for C₂H₆). In situ Raman spectroscopy was performed to examine catalytic events at the electrode interface and determine the unique selectivity toward AA during the KBE reaction.