Knowra Chlor-alkali process Chlor-alkali process The chlor-alkali process electrolyzes aqueous sodium chloride to produce chlorine gas, hydrogen gas, and sodium hydroxide. Its main industrial methods differ in how they separate products and manage the electrolyte.
Chlorine evolution reaction : An electrochemical reaction that oxidizes chloride ions to chlorine gas at an anode. This anodic reaction releases the process’s chlorine product.
Brine : Water containing a high concentration of dissolved salt, commonly sodium chloride. Purified brine supplies the chloride and sodium ions consumed or transported in the cell.
Polyvinyl chloride : A synthetic polymer made from vinyl chloride and used in pipes, cables, flooring, and other products. Chlorine from the process is a major feedstock for vinyl chloride production.
Mercury pollution : Environmental contamination caused by the release and accumulation of mercury in air, water, or soil. Mercury-cell plants can release mercury, motivating their replacement and strict controls.
Hydrogen evolution reaction : An electrochemical reaction that reduces water or protons to hydrogen gas. Water reduction produces hydrogen at the cathode.
Electrolysis : The use of electrical energy to drive a nonspontaneous chemical reaction. The process is an industrial application of electrolysis.
Sodium hydroxide : A strong base used in chemical manufacturing, pulp and paper production, and cleaning. It is one of the process’s principal products and has broad industrial demand.
Ion-exchange membrane electrolysis : Electrolysis using an ion-selective membrane to separate electrode compartments and control ion transport. The membrane-cell route avoids the mercury cathode and porous diaphragm used in older technologies.
Cation-exchange membrane : A membrane that preferentially transports positively charged ions while restricting negatively charged ions. It lets sodium ions reach catholyte while limiting chlorine and hydroxide crossover.
Sodium chloride : An ionic compound composed of sodium and chloride ions, commonly known as table salt. Dissolved sodium chloride provides the feedstock for all three products.
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