Electrochemical Methods of Carbon-Negative Ironmaking for Green Steel

Iron and steel are important feedstocks for energy materials and infrastructure but are produced with concomitant greenhouse gas emissions. Iron reduction, typically accomplished using coal or natural gas, can be driven electrochemically which provides a potential path to a fully electrified and carbon-neutral steelmaking process. We have developed the chlor-iron process, a low-temperature (<100 C), electrochemical cell that directly reduces solid iron oxide particles to high-purity iron metal at the cathode while co-producing sodium hydroxide and chlorine. The production of co-products consumed at the ~100 million tons per year scale provides a cost-competitive pathway for electrochemical ironmaking. Moreover, the co-produced hydroxide can be used for direct CO₂ capture and mineralization, leading to a net-negative process for ironmaking. Here, we report results on the mechanism of electrochemical direct oxide reduction, the effects of iron ore feedstocks on selectivity towards iron metal, and prototypes for a cell producing iron and chlorine at current densities > 100 mA cm^-2.