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Abstract

The present disclosure provides a method for preparing an alkali and co-producing gypsum, and belongs to the technical field of chemical production. The method comprises the steps of placing a cation exchange membrane into an electrolytic cell, adding a solution of sodium salt of a weak acid and a compound MH to an anode region as an anode electrocatalyst, adding sodium carbonate or sodium hydroxide to a cathode region, adding a compound M as a cathode electrocatalyst, and applying a DC power supply between a cathode electrode and an anode electrode. The electrolysis oxidizes the MH into the M and releases H⁺, Na⁺ in the anolyte penetrates through the cation exchange membrane to reach a cathode region to be combined with OH⁻ in the catholyte to generate NaOH, or further absorbs CO₂ and converts into Na₂CO₃; the anolyte containing a large amount of H⁺ is generated by the electrolysis for dissolution reaction with limestone, and the H⁺ is consumed to generate Ca²⁺, and SO₄²⁻ and Ca²⁺ are combined to generate high-purity CaSO₄ precipitate. According to the present disclosure, a compound capable of generating PCET reaction is used as an electrocatalyst, while M is its oxidation state and MH is its reduction state, and mirabilite and limestone are used as raw materials to realize the preparation of soda ash, caustic soda and gypsum.

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First Claim