Sodium Sulfate Salt Splitting for Electrochemical Decarbonization of Cement Manufacturing

Résumé fourni par la source

Electrochemical salt splitting is well established for chlor-alkali systems and bipolar membrane electrodialysis, yet sulfate-based (Na 2 SO 4 ) splitting remains less explored in zero-gap architectures and has not been evaluated in the context of Ca-bearing chemical loops relevant to cement decarbonization. Building on our prior work in electrochemical CaCO 3 conversion, this study addresses the challenge of producing cement clinker intermediate (Ca(OH) 2 ) without CO 2 gas evolution by coupling Na 2 SO 4 electrolysis to an external double-displacement reaction with gypsum. Membranes and pH-gradient stability were first assessed in H-cell configurations using open-circuit voltage diagnostics, followed by systematic evaluation in a zero-gap flow electrolyzer across multiple current densities and catholyte volumes, with impedance spectroscopy used to deconvolute ohmic and interfacial losses. Reinforced PFSA membranes sustain stable acid–base separation, supporting NaOH generation with Faradaic efficiencies exceeding 90% under balanced flow operation up to 75 mA cm −2 and enabling Ca(OH) 2 formation with ≥85% purity while allowing direct Na 2 SO 4 reuse essential for closed loop. These results establish sulfate salt splitting as a viable carbonate-free pathway to Ca(OH) 2 and identify membrane selectivity, water transport, and gas disengagement as central constraints for scalable, low-carbon cement processing.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.