Redox Mediator to Accelerate the Electrosynthesis of Dimethyl Carbonate

We have developed an Pd-Au catalyst for the electrosynthesis of dimethyl carbonate (E-DMC) from methanol and CO. While the catalyst displays high (>90%) faradaic efficiency for dimethyl carbonate, the resulting current density is too low to be of commercial use. To accelerate the production, we have expanded the catalytic environment by incorporating redox halide mediators. Both LiCl and LiBr enhanced the current density by more than fivefold. We have identified 5 steps in the reaction for E-DMC that take place on the surface of the Pd-Au catalyst without the redox mediator. With the redox mediator, indications are that carbonyl halide is synthesized at the surface of the metal alloy and then in the electrolyte, the halogens are replaced by methanols to produce DMC. This pathway requires only one reaction step at the surface of the alloy, freeing up catalytic sites, leading to faster production. It is worth noting that this route produces and consumes organic halides in the same reaction and may lead to less toxicity.