A clean and membrane-free chlor-alkali process with decoupled Cl<sub>2</sub> and H<sub>2</sub>/NaOH production.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29382835.
- Also identified by DOI 10.1038/s41467-018-02877-x and PMC identifier 5789859.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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<sup>+</sup> de-intercalation/intercalation of a Na<sub>0.44</sub>MnO<sub>2</sub> electrode as a redox mediator, we decouple the chlor-alkali process into two independent steps: a H<sub>2</sub> production step with the NaOH formation in the electrolyte and a Cl<sub>2</sub> production step. The first step involves a cathodic H<sub>2</sub> evolution reaction (H<sub>2</sub>O → H<sub>2</sub>) and an anodic Na<sup>+</sup> de-intercalation reaction (Na<sub>0.44</sub>MnO<sub>2</sub> → Na<sub>0.44-x</sub>MnO<sub>2</sub>), during which NaOH is produced in the electrolyte solution. The second step depends on a cathodic Na<sup>+</sup> intercalation reaction (Na<sub>0.44-x</sub>MnO<sub>2</sub> → Na<sub>0.44</sub>MnO<sub>2</sub>) and an anodic Cl<sub>2</sub> production (Cl → Cl<sub>2</sub>). The cycle of the two steps provides a membrane-free process, which is potentially a promising direction for developing clean chlor-alkali technology.