Investigation of the Electrochemical Acetone Reduction Reaction in a PEM-Setup

The electrochemical energy storage in organic compounds has gained increasing interest in recent years. The acetone reduction can serve simultaneously as a model compound for electrochemical ketone reduction and as an electrochemical liquid organic hydrogen carrier. This study investigates the influence of temperature and concentration on the electrochemical acetone reduction reaction (ARR) to isopropanol (2-propanol) in a membrane electrode assembly. It reports, in particular, on the faradaic efficiency and performance of the system both in fuel cell mode (above 0 V vs RHE) and in hydrogen pumping mode (below 0 V vs RHE). This investigation is performed by applying cyclovoltammetry, electrochemical impedance spectroscopy (EIS), and amperometry. Shape analysis of the recorded EIS data is performed, and mass transport limitation is identified as one major problem of this configuration. Additionally, thermocatalytic experiments are conducted to ensure comparability, and the specific reaction rates of both approaches are compared to each other, thus emphasizing the importance of referencing when performing electrochemical reduction experiments. Propane formation has been found as a relevant side reaction of the ARR in thermocatalytic and electrocatalytic experiments.