A clean and membrane-free chlor-alkali process with decoupled Cl2 and H2/NaOH production

• Published in: Nature communications Vol. 9; no. 1; pp. 1 - 8
• Main Authors: Hou, Mengyan, Chen, Long, Guo, Zhaowei, Dong, Xiaoli, Wang, Yonggang, Xia, Yongyao
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.01.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/161; 639/638/440; Asbestos; Chlorine; Electrolytes; Fluorine; Humanities and Social Sciences; Hydrogen production; Intercalation; Mercury; multidisciplinary; Science; Science (multidisciplinary); Sodium; Sodium hydroxide
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-02877-x

Existing chlor-alkali processes generally use asbestos, mercury or fluorine-containing ion-exchange membranes to separate the simultaneous chlorine production on the anode and hydrogen production on the cathode, and form sodium hydroxide in the electrolyte. Here, using the Na + de-intercalation/intercalation of a Na 0.44 MnO 2 electrode as a redox mediator, we decouple the chlor-alkali process into two independent steps: a H 2 production step with the NaOH formation in the electrolyte and a Cl 2 production step. The first step involves a cathodic H 2 evolution reaction (H 2 O → H 2 ) and an anodic Na + de-intercalation reaction (Na 0.44 MnO 2  → Na 0.44− x MnO 2 ), during which NaOH is produced in the electrolyte solution. The second step depends on a cathodic Na + intercalation reaction (Na 0.44− x MnO 2  → Na 0.44 MnO 2 ) and an anodic Cl 2 production (Cl → Cl 2 ). The cycle of the two steps provides a membrane-free process, which is potentially a promising direction for developing clean chlor-alkali technology. The chlor-alkali process is an important industrial process to make commodity chemicals; however, it usually requires the use of dangerous chemicals as membrane material. Here, the authors demonstrate clean, membrane-free chlor-alkali electrolysis, where chlorine evolution and hydrogen/sodium hydroxide production are completely decoupled.