Two-step process chlorine-alkali electrolytic method and device adopting double electrolytic cells based on three-electrode system

Abstract

The invention belongs to the technical field of the chlorine-alkali industry, and specifically discloses a two-step process chlorine-alkali electrolytic method and device adopting double electrolytic cells based on a three-electrode system. The device comprises two independent electrolytic cells (a cell-A and a cell-B), a hydrogen evolution catalytic electrode, a chlorine evolution catalytic electrode and a sodium storage electrode capable of reversibly storing sodium ions. According to the method, a process of electrolyzing a salt solution or seawater is divided into a step of producing hydrogen gas / sodium hydroxide and a step of producing chlorine, which are separately completed in the two independent electrolytic cells (cell-A and cell-B). An electrolytic process in the electrolytic cell-A and an electrolytic process in the electrolytic cell-B are alternately carried out in a circulating manner. According to the method, a step of simultaneously producing hydrogen gas / sodium hydroxide and producing chlorine during conventional electrolysis of the salt solution or the seawater is divided, so that the step of producing hydrogen gas / sodium hydroxide and the step of producing chlorine are separately completed in different electrolytic cells while the desalination of the salt solution or the seawater is realized; and furthermore, the cost of the chlorine-alkali industry is further reduced, the safety is greatly improved and the purity of the generated sodium hydroxide is effectively guaranteed while the desalination of the salt solution or the seawater is realized.

Description

technical field [0001] The invention belongs to the technical field of chlor-alkali industry, and in particular relates to a two-step chlor-alkali electrolysis method and device based on a three-electrode system. Background technique [0002] The chlor-alkali industry is one of the most basic chemical industries. Its products are not only used in the chemical industry itself, but also widely used in light industry, textile industry, metallurgical industry, petrochemical industry and public utilities. 50% of the total turnover of the chemical industry depends on the Cl of the chlor-alkali industry 2 and caustic soda. Caustic soda is widely used in textile industry, refined petroleum, paper industry, metallurgical industry and chemical industry and other industries. Cl 2 Downstream products continue to evolve, 34% Cl 2 Production of PVC through dichloroethane and vinyl chloride monomers, 20% for the production of other organics, 15% for the production of hydrogen chloride,...

AI Technical Summary

Problems solved by technology

Its advantage is that the lye only contains trace salt, the caustic soda has high purity, its operation is relatively easy to control, and its ability to adapt to load changes is large; the disadvantage is that the quality of brine is high, the ion membrane is expensive, and the service life of the ion exchange membrane is limited

In addition, even under the condition of using an ion exchange membrane, the hydrogen and chlorine gas generated in the same electrolytic cell may still mix through the ion exchange membrane, which poses a certain safety hazard and requires precise control of the entire electrolyte process

On the other hand, the caustic soda (Na(OH) 2 ) still contains a small amount of sodium chloride impurities, further purification process will greatly increase the preparation cost

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