Electrochemical Hydrogenation of Aliphatic Aldehydes and Acids using Pentlandite Catalysts

Electrochemical hydrogenations are considered a sustainable alternative to classical thermocatalytic processes prevalent in industrial conversions. Using a base metal sulfide of the pentlandite class, the hydrogenation of glutaraldehyde and propionic acid was investigated. While propionic acid could not be converted, glutaraldehyde was conveniently transformed to the semi- and fully hydrogenated products 5-hydroxypentanal and 1,5-pentanediol with a partial current density of up to 34 mA cm-2 and a Faraday efficiency of 34 %. Crucial factors for a stable and efficient reaction were found to be the use of an appropriate buffer, avoidance of low pH and the used membrane type. The reaction was implemented into a zero-gap cell reaching a single pass conversion of up to 22 %, underlining the potential for future application. The electrochemical hydrogenation of biomass-derived dialdehydes enables a sustainable route towards green alpha,omega-diols. Specifically, for glutaraldehyde, the influence of cell components and electrolyte on the efficiency of the reaction is exemplified and continuous operation in a scalable zero-gap electrolyzer demonstrated. image