Electrolytic cement clinker production sustained through orthogonalization of ion vectors

Electrochemical reactors can reduce the carbon intensity of cement production by using electricity to convert limestone (CaCO3) into Ca(OH)2, which can then be combined with silica (SiO2) at high temperatures to produce cement clinker. A key challenge with this method is the deposition of solid Ca(OH)2 at the reactor membrane leads to unacceptably low energy efficiencies. To address this challenge, we connected the electrochemical reactor (“cement electrolyser”) to a distinctive chemical reactor (“calcium reactor”) so that Ca(OH)2 could form there instead, and not within the electrochemical reactor. In this tandem system, the cement electrolyser generated H+ and OH– in the respective chemical and cathode compartments. The H+ then reacted with CaCO3 to form Ca2+ ions, which were diverted into the calcium reactor to react with the OH– to form Ca(OH)2. We fabricated a composite membrane to selectively block the transport of Ca2+ into the cathode compartment. Charge balance in the cement reactor was enabled with monovalent ions (e.g., K+) as the positive charge carrier. This orthgonalized ion management was validated by operando imaging. The tandem reactor enabled the electrolysis process to operate for 50 hours at 100 mA cm-2 without any voltage increase, which represents a meaningful step forward for cement clinker precursor production.