Preparation process of trifluoroacetic acid

Abstract

The invention discloses a preparation process of trifluoroacetic acid. The preparation process comprises the following steps: (1) reacting reaction materials sodium trifluoroacetate and sulfuric acidto generate a trifluoroacetic acid and sodium sulfate mixture; (2) conveying the mixture to an extraction tower, and extracting by adding ethanol; and (3) rectifying and separating the extracted ethanol and trifluoroacetic acid mixture through a rectifying tower, returning the ethanol at the bottom of the rectifying tower to an extraction tower for recycling, and obtaining a high-purity trifluoroacetic acid product at the top of the rectifying tower; according to the method, the byproduct sodium trifluoroacetate generated in the upstream process is recycled, the upstream byproduct sodium trifluoroacetate is recycled, the trifluoroacetic acid product with high added value is produced, the ethanol in the process route is recycled, economic benefits are created, and the production cost is effectively reduced.

Description

technical field [0001] The invention relates to a preparation process of trifluoroacetic acid, which is used for preparing trifluoroacetic acid and belongs to the technical field of preparation of fluorine-containing organic acids. Background technique [0002] At present, the production of TFA mainly includes the following processes: [0003] (1) With trifluorotrichloroethane (CFC-113a) and SO 3 It is used as raw material to synthesize trifluoroacetic acid under the catalysis of mercury. At present, domestic enterprises such as Changshu Sanaifu mainly use this method for the production of trifluoroacetic acid. The disadvantage of this method is that it uses a toxic mercury salt catalyst and produces a large amount of by-products. Chlorine sulfate increases the difficulty of subsequent treatment. [0004] (2) Using trifluorodichloroethane (HCFC-123) as a raw material, it is mixed with oxygen gas at high temperature and then reacted with a fixed bed catalyst to generate tri...

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Problems solved by technology

[0003] (1) With trifluorotrichloroethane (CFC-113a) and SO 3 As a raw material, it reacts and synthesizes trifluoroacetic acid under the catalysis of mercury. At present, domestic enterprises such as Changshu Sanaifu mainly use this method to produce trifluoroacetic acid. The disadvantage of this method is that it uses a toxic mercury salt catalyst and produces a large amount of by-products. Chlorine sulfate, increasing the difficulty of subsequent treatment

[0004] (2) Using trifluorodichloroethane (HCFC-123) as a raw material, it is mixed with oxygen gas at high temperature and then reacted with a fixed bed catalyst to generate trifluoroacetic acid. The reaction produces trifluoroacetyl chloride and also produces CFC by-product -113a, the utilization rate of raw materials is low, and the carrier activated carbon loaded with catalyst is easily deactivated in a high-temperature nutrient-rich environment, resulting in a short service life of the catalytic meter, which cannot meet the requirements of industrial production

[0006] (4) Using trifluoroethanol as a raw material, it reacts catalytically with hydrogen peroxide liquid phase at low temperature to produce trifluoroacetic acid. After industrial scale-up production, the conversion rate of trifluoroethanol can reach 100%, and the selectivity of trifluoroacetic acid can reach 96%. But the cost price of trifluoroethanol is too high and has no process development value

[0007] (5) Using trifluorodichloroethane (HCFC-123) as raw material, under low temperature conditions, trifluoroacetyl chloride is prepared by photocatalysis and oxygen reaction, and further absorbed by water to generate trifluoroacetic acid. This method is carried out by light Catalytic reaction, green and environmental protection, but still in the stage of theoretical research, it is difficult to realize process development

[0009] (1) In the above-mentioned processes, catalysts are generally required for catalytic reactions, the cost is high, and the activity of catalysts is affected by various factors

[0010] (2) The cost is relatively high, especially the cost price of trifluoroethanol is higher than the price of the product trifluoroacetic acid, and there is no feasibility of market development

[0011] (3) In addition to using trifluoroethanol as a raw material, the selectivity of other process routes is not high

[0012] (4) The processing cost of the spent catalyst involved is relatively high

[0013] (5) The catalytic reaction process is complex and the operation process is cumbersome

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