Preparation method of potassium perfluorobutanesulfonate

Abstract

The invention discloses a preparation method of potassium perfluorobutanesulfonate. The method adopts continuous fluid reaction to replace batch-type kettle reaction, and comprises the following steps: (i) providing a tubular reactor; (ii) continuously adding perfluorobutyl sulfonyl fluoride and aqueous slurry of potassium hydroxide and calcium hydroxide into the tubular reactor at a reaction temperature of 70-100 DEG C under a pressure sufficient to keep the perfluorobutyl sulfonyl fluoride in a liquid state; (iii) drying the reaction mixture to obtain a solid containing calcium fluoride andpotassium perfluorobutanesulfonate; (iv) carrying out high-temperature dissolution on the solid by adopting ethanol, wherein the dissolution temperature is 65-76 DEG C; and (v) crystallizing the dissolved ethanol solution containing potassium perfluorobutanesulfonate to obtain potassium perfluorobutanesulfonate.

Description

technical field [0001] The invention relates to a method for preparing potassium perfluorobutane sulfonate through continuous reaction. The method can continuously produce potassium perfluorobutanesulfonate, has high heating efficiency, uses a temperature higher than the boiling point of the perfluorobutylsulfonyl fluoride raw material for the reaction, has low water consumption, and has a fast reaction rate, and the perfluorobutylsulfonyl fluoride raw material can Full conversion, high production capacity, and the heat generated by the reaction is recycled, which saves energy compared with conventional methods, and solves the problem that the existing reaction device has a long heating time, perfluorobutylsulfonyl fluoride cannot be completely converted, and the by-product calcium fluoride is difficult to precipitate. Separation, low product purity, low production efficiency and other shortcomings Background technique [0002] Potassium perfluorobutane sulfonate is an impo...

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Problems solved by technology

[0010] (i) Since the hydrolysis reaction of a large amount of perfluorobutylsulfonyl fluoride is violent and exothermic, existing methods emphasize that perfluorobutylsulfonyl fluoride must be "slowly added dropwise" or "slowly and continuously added" to avoid violent reactions The temperature and pressure of the system are suddenly raised, which makes the whole reaction process longer; at the same time, because the boiling point of perfluorobutylsulfonyl fluoride is 64 ° C and is volatile, higher than this temperature (70-80 ° C), perfluorobutyl sulfonyl fluoride Butylsulfonyl fluoride boils and evaporates, and there will be a large amount of perfluorobutylsulfonyl fluoride in the free space of the reactor, which is easy to leak and waste raw materials; when the reaction is lower than this temperature, there will also be a small amount of unreacted perfluorobutylsulfonyl fluoride mixed in In the reaction system, it will cause difficulties for subsequent separation

[0011] (ii) After the reaction, because the particle size of calcium fluoride is too fine, it is difficult to separate by filtration in the actual processing process, and it can only be separated by static layering, which prolongs the production time and remains in the separated calcium fluoride. A large amount of potassium perfluorobutanesulfonate is difficult to remove, which not only wastes the product, but also affects the purity of the by-product calcium fluoride

[0012] (iii) reaction uses water as solvent, and water is low to perfluorobutane sulfonate potassium solubility, is easy to make perfluorobutane sulfonate potassium product crystallization mix in calcium fluoride in calcium fluoride filtration process; Use water and ethanol (ethanol The effect is to increase the solubility of perfluorobutanesulfonyl fluoride in the reaction system) mixed solution as solvent, not only can produce the above-mentioned problems, but also make the total amount of potassium perfluorobutanesulfonate contained in the solvent in the follow-up crystallization process large, and the loss increases ; The above problems have finally led to problems such as low production efficiency and low product purity in the existing preparation method

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