Glycerol Electro-Oxidation via Solketal: Industrially Viable?

The mismatch between the demand for glycerol and its supply as a byproduct of biodiesel production is rising. Glycerol electro-oxidation is known as a promising valorization route. It also serves as an alternative anode reaction for water splitting, potentially enabling lower potentials and thus energy savings within green hydrogen production. However, this approach suffers from many reaction pathways with low selectivity and C–C cleavage, forming less valuable products. By implementing an acetalization step before the electrolysis, these drawbacks can be overcome in the electro-oxidation of solketal in alkaline media, increasing the selectivity to glyceric acid from around 5% up to 84%. Starting from experimental results, we perform a technoeconomic analysis to evaluate the industrial potential. Based on this, we optimize the experimental conditions, leading to a 10-fold increase in current density of up to 0.12 A/cm2 and a break-even price of 4.9 €/kg of glyceric acid. Overall, we demonstrate that the oxidation of glycerol via solketal to glyceric acid, coupled with hydrogen production, is an economically promising process, with high current density and selectivity as the key adjustment points for future improvements.