Indirect H2O2 synthesis without H2

Abstract

Industrial hydrogen peroxide (H₂O₂) is synthesized using carbon-intensive H₂ gas production and purification, anthraquinone hydrogenation, and anthrahydroquinone oxidation. Electrochemical hydrogenation (ECH) of anthraquinones offers a carbon-neutral alternative for generating H₂O₂ using renewable electricity and water instead of H₂ gas. However, the H₂O₂ formation rates associated with ECH are too low for commercialization. We report here that a membrane reactor enabled us to electrochemically hydrogenate anthraquinone (0.25 molar) with a current efficiency of 70% at current densities of 100 milliamperes per square centimeter. We also demonstrate continuous H₂O₂ synthesis from the hydrogenated anthraquinones over the course of 48 h. This study presents a fast rate of electrochemically-driven anthraquinone hydrogenation (1.32 ± 0.14 millimoles per hour normalized per centimeter squared of geometric surface of electrode), and provides a pathway toward carbon-neutral H₂O₂ synthesis.

Industrial hydrogen peroxide is produced at scale using hydrogen gas derived from fossil fuels. Here, the authors demonstrate production of hydrogen peroxide electrochemically from hydrogenation of anthraquinones using a membrane reactor.