A kind of preparation method of ammonium hexafluorophosphate

Abstract

The invention provides a preparation method of ammonium hexafluorophosphate. The preparation method includes: sequentially adding solid ammonium bifluoride, anhydrous hydrogen fluoride and phosphorusoxychloride into a reaction kettle to obtain primary reaction liquid, adding a certain amount of methanol into the reaction kettle to obtain secondary reaction liquid, dropwise adding ammonia water into the reaction kettle to obtain tertiary reaction liquid after sufficient reaction, performing solid-liquid separation on the tertiary reaction liquid to obtain precipitates and quaternary reaction liquid, transferring the quaternary reaction liquid into a concentrating kettle to perform vacuum concentration to obtain methanol gas and ammonium hexafluorophosphate mother liquor, and transferring the ammonium hexafluorophosphate mother liquor into a crystallizing kettle to perform cooling crystallization to obtain the finished-product ammonium hexafluorophosphate. The preparation method has theadvantages that the ammonium hexafluorophosphate is prepared by dissolving the ammonium bifluoride into the anhydrous hydrogen fluoride and dropwise adding the phosphorus oxychloride, the reaction iseasy to control, mild, gentle in speed and safe, operation difficulty is lowered, production cost is lowered at the same time, and production cycle is also shortened.

Description

technical field [0001] The invention relates to the technical field of preparation of ammonium hexafluorophosphate, in particular to a preparation method of ammonium hexafluorophosphate. Background technique [0002] Hexafluorophosphate series is a very important class of inorganic fluorine salts, among which, ammonium hexafluorophosphate is a relatively important one in hexafluorophosphate, which can be used to prepare other hexafluorophosphates, and is also an important tool for preventing dental caries. substance. The preparation method of hexafluorophosphate has been greatly developed because of the important application of lithium hexafluorophosphate, which has greatly improved the production process of ammonium hexafluorophosphate. [0003] In the existing method, the reaction of phosphorus pentachloride and ammonium fluoride is generally only suitable for a small amount of temporary preparation in the laboratory, because the reaction trigger of the two solids is not ...

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Problems solved by technology

[0003] In the existing method, the reaction of phosphorus pentachloride and ammonium fluoride is generally only suitable for a small amount of temporary preparation in the laboratory, because the reaction trigger of the two solids is not easy, and the reaction will proceed spontaneously after triggering, which is difficult to control; When phosphorus gas reacts with ammonium fluoride, phosphorus pentafluoride gas needs to be prepared now, and phosphorus pentafluoride gas is mixed with hydrochloric acid gas, which needs to be separated; phosphorus pentafluoride reacts with ammonium fluoride, in fact, it should be reacted with ammonium bifluoride In these reactions, easily decomposed phosphorus pentachloride solid is used in the preparation of phosphorus pentafluoride, and phosphorus pentafluoride gas is used in the synthesis of ammonium hexafluorophosphate, which increases the difficulty of reaction control, and a large number of unstable, The use of corrosive and toxic raw materials increases the risk of reaction operations; ammonium hexafluorophosphate is prepared by reacting ammonium chloride, anhydrous hydrogen fluoride, and phosphorus pentachloride, and the solid phosphorus pentachloride requires a small amount of chlorine to be added several times In the mixture of ammonium chloride and anhydrous hydrogen fluoride, due to the violent reaction, this operation is more difficult for the reaction control. If the speed is too fast, it is easy to cause danger, and if the speed is too slow, the production cycle will be prolonged.

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