Understanding the effects of forced and bubble-induced convection in transport-limited organic electrosynthesis

Organic electrosynthesis offers a sustainable path to decarbonize the chemical industry by integrating renewable energy into chemical manufacturing. However, achieving the selectivity and energy efficiency required for industrial applications is challenging due to the inherent mass transport limitations. Convection can mitigate mass transport limitations, but its impact on organic electrochemical processes remains poorly understood. We investigate the interplay between mass transport and electrochemical reaction rates under convective flows in the context of the electrosynthesis of adiponitrile, one of the largest organic electrochemical processes in the industry. We use experiments and data-driven predictive models to demonstrate that forced liquid convection and bubble-induced convection produce near-identical mass transport conditions when the corresponding Sherwood numbers—the ratio of convective mass transport to diffusive mass transport—are equal. Moreover, we show that the Faradaic efficiency (i.e., the electrochemical selectivity) scales with the Sherwood number for a given current density and reactant concentration. This scalability enables performance to be predicted irrespective of the convection mode employed to enhance mass transport. Our results provide a deeper understanding of mass transport in organic electrosynthesis and offer guidelines to enable more sustainable chemical manufacturing practices.