Enhancing selectivity and efficiency in the electrochemical synthesis of adiponitrile

Adiponitrile is a large scale chemical intermediate used in the production of Nylon 6,6. It is primarily produced via two methods: the thermal hydrocyanation of butadiene and the electrochemical hydrodimerization of acrylonitrile. The thermochemical method is an energy intensive process that involves acutely toxic reactants such as hydrogen cyanide. On the other hand, the electrosynthesis of adiponitrile is a green chemical process that uses water-based electrolytes and can be directly coupled with renewable electricity sources such as wind or sunlight. Although this process is the largest organic electrochemical process in industry, it still faces many challenges owing to its low energy conversion efficiency and selectivity. Using a systematic approach, this study provides insights into mass transport and kinetic factors that influence the reaction performance, and demonstrates that by careful control of the composition of the electrolyte, concentration of reactants, operating current densities, and temperature, selectivities as high as 83% can be achieved. Our results provide electrochemical engineering guidelines to significantly improve the efficiency of the electrochemical production of adiponitrile and open up opportunities to the direct implementation of renewable-energy sources in chemical manufacturing.