Electrolysis of medium chain carboxylic acids to aviation fuel at technical scale

Abstract

For mobility, especially in aviation, cargo weight and volume of the energy vector are substantially more limited than in any other form of transportation. Therefore, energy vectors with high mass and volume specific energy density are needed, for which carbon based liquid fuels are unmatched. Concurrently, there is an imperative of deriving these fuels from non-fossil sources. Here, we show the scale-up of the production of aviation drop-in fuel-like mixtures (mainly n-decane) that are obtained by Kolbe electrolysis of medium chain carboxylic acids (n-hexanoic acid), which can be derived from biomass. We increased the scale to 1 L volume and 100 cm2 electrode surface area within a single stack electrolysis cell allowing straightforward numbering-up. The obtained electrolysis performance is unprecedented at technical scale with a maximum n-decane production rate of 0.73 g L−1h−1 cm−2, a selectivity for n-decane between 76.3 % and 97.8 % and Coulombic efficiencies up to 68 %.