Herein, we describe a study of the electrochemical reduction of oxalic and glyoxylic acids toward a feasible green and sustainable production of tartaric acid in aqueous and/or acetonitrile solvent using silver and lead electrodes. Our results show that on the silver electrode, for both oxalic acid and glyoxylic acid, the reduction reaction is more favorable toward the dimerization step, leading to tartaric acid, due to the increase in the local pH, while on the lead electrode, the step involving the protonation of the intermediate is more favorable, leading to the formation of glycolate. Techno-economic analysis shows that tartaric acid production from glyoxylic acid and from oxalic acid via electrochemical synthesis can be a potential process at the industrial scale. In the present case, the oxygen evolution reaction was chosen as the reaction at the other electrode for practical reasons, but oxygen is a low-value product. Another anodic reaction with a more valuable oxidation product can be selected to increase the profitability of the overall electrochemical process and thereby decrease the total production costs of tartaric acid.

In industrial electrochemical processes it is of paramount importance to achieve efficient, selective processes to produce valuable chemicals while minimizing the energy input. Although the electrochemical reduction of CO ₂ has received a lot of attention in the past decades, an economically feasible process has not yet been developed. Typically, the electrochemical reduction of CO ₂ is paired to water oxidation, forming oxygen, but an alternative strategy would be coupling the CO ₂ reduction reaction to an oxidation in which a higher-value product is co-produced, significantly improving the economic feasibility for CO ₂ reduction as a whole. Importantly, both reactions need to be chosen wisely to ensure their compatibility and to minimize the voltage requirements for the redox system. In this study, as an example of this approach, we demonstrate such a match: the electroreduction of CO ₂ to CO, paired with the electrooxidation of 1,2-propanediol to lactic acid. Combining these reactions decreases energy consumption by 35%, increases product value of the system, and results in combined faradaic efficiencies of up to 160% when compared to the CO ₂ reduction reaction in which oxygen is formed in the anode.