Process for removing fluorine from trifluoroacetic acid

Abstract

The invention discloses a process for removing fluorine from trifluoroacetic acid. The process comprises the following steps of: adding fluorine-containing trifluoroacetic acid and excessive active aluminum oxide into a reaction kettle, wherein complex reaction is performed on fluorine-containing impurities in the trifluoroacetic acid and the active aluminum oxide; and AlF2+ complex ions produced by the complex reaction are adsorbed on the surface of the active aluminum oxide; continuously distilling the trifluoroacetic acid, from which the fluorine is removed, out of the reaction kettle, condensing and collecting the trifluoroacetic acid; continuously adding both the fluorine-containing trifluoroacetic acid and the active aluminum oxide into the reaction kettle at the same time to keep liquid level in the reaction kettle constant; and pumping out the active aluminum oxide, to which the AlF2+ complex ions are adsorbed, from the bottom of the reaction kettle, removing the active aluminum oxide by filtration of a filter, and circulating filtrate into the reaction kettle. The process of the invention has the advantages of short process flow, easy operation, high fluorine removal efficiency, cheap and readily available fluorine removing agent and low fluorine removal cost.

Description

technical field [0001] The invention relates to a defluorination process, in particular to a trifluoroacetic acid defluorination process. technical background [0002] Trifluoroacetic acid is the main raw material for introducing trifluoromethyl groups into many fluorine-containing fine chemical products. In addition, it has great application potential in the fields of materials, solvents, and catalysts. [0003] The trifluoroacetic acid obtained by hydrolysis of the trifluoroacetyl chloride obtained by the photochemical oxidation of trifluorodichloroethane or the mixture of trifluorochloroethane and trifluorodichloroethane contains a certain amount of fluorine ions. After the ionic trifluoroacetic acid products are sold directly or distributed to users through intermediate dealers, some users may cause equipment corrosion, leakage and other safety hazards and accidents due to incorrect use methods. Fluorine-containing wastewater that meets the standard will cause fluorine ...

AI Technical Summary

Problems solved by technology

[0003] The trifluoroacetic acid obtained by hydrolysis of the trifluoroacetyl chloride obtained by the photochemical oxidation of trifluorodichloroethane or the mixture of trifluorochloroethane and trifluorodichloroethane contains a certain amount of fluorine ions. After the ionic trifluoroacetic acid products are sold directly or distributed to users through intermediate dealers, some users may cause equipment corrosion, leakage and other safety hazards and accidents due to incorrect use methods. Fluorine-containing waste water up to the standard will cause fluorine pollution in the surrounding environment, etc., which will lead to safety and environmental protection issues

[0004] Therefore, the problem of fluoride removal by fluorine-containing trifluoroacetic acid is particularly urgent. Generally, it is required that the fluoride ion content in trifluoroacetic acid be less than 100ppm when it leaves the factory. That is to say, when the trifluoroacetic acid is purified by rectification, the front fraction is collected and removed. The disadvantage of this method is to ensure that the fluoride ion content in the trifluoroacetic acid is ≤ 100ppm, and the collected front fraction will inevitably bring out a lot of trifluoroacetic acid, resulting in trifluoroacetic acid waste