Closing the Gap: Towards a Fully Continuous and Self‐Regulated Kolbe Electrosynthesis

Abstract

AbstractIn this article, we address the transition of the Kolbe electrolysis of valeric acid (VA) to n‐octane as an exemplary electrosynthesis process from a batch reaction to a continuous, self‐regulated process. Based on a systematic assessment of chemical boundary conditions and sustainability aspects, we propose a continuous electrosynthesis including a simple product separation and electrolyte recirculation, as well as an online‐pH‐controlled VA feeding. We demonstrate how essential performance parameters such as product selectivity (S) and coulombic efficiency (CE) are significantly improved by the transition from batch to a continuous process. Thus, the continuous and pH‐controlled electrolysis of a 1 M valeric acid, starting pH 6.0, allowed a constantly high selectivity of around 47 % and an average Coulomb efficiency about 52 % throughout the entire experimental duration. Under otherwise identical conditions, the conventional batch operation suffered from lower and strongly decreasing performance values (Sn‐octane, 60min=10.4 %, Sn‐octane, 240min=1.3 %; CEn‐octane, 60min=7.1 %, CEn‐octane, 240min=0.5 %). At the same time, electrolyte recirculation significantly reduces wastes and limits the use of electrolyte components.