Sustainable alkane production from waste fatty acids via electrochemically coupled decarboxylation and hydrogenation

Upgrading fatty acid derivatives is a promising route to sustainable diesel and jet fuels, but conventional processes require high temperature, pressure, and large H₂ input, while contaminants in waste oil deactivate catalysts, demanding costly purification. Here, we present an integrated electrochemical strategy combining anodic decarboxylation, cathodic proton reduction, and olefin hydrogenation in one reactor, upgrading fatty acid derivatives to long-chain alkanes under mild conditions (60 °C, 1 atm) without external hydrogen. A high alkane yield of 88.9% is achieved and the reported performance is competitive. Experiments and calculations reveal that fatty acid chain length governs product yield and distribution by influencing -H departure and C_γ-C_β-COOH bond cleavage barriers. This approach shows high activity and selectivity toward diverse feedstocks, including unsaturated fatty acids, esters, mixtures, crude acids, and waste oils. Powered by solar energy, approximately 40 g of long-chain alkanes are produced in a 1 L reactor, highlighting its scalability and potential for green fuel synthesis.