Daikin Industries, Ltd.

E.i. Dupont De Nemours and Company

Takuya Ichida

Steven Henry Swearingen

Takeomi Hirasaka

Ta-Wei Fu

Yuuki Matsuda

Shuji Itatani

Masahiro Kondo

Yukio Homoto

Noriaki Shibata

Kazuyoshi Ichihara

Masaki Kuramitsu

Shigeyuki Yoshii

Kaori Ohno

Disclosed are an adsorption process whereby a fluorocarboxylic acid having an ether bond can be adsorbed to a high extent by using active carbon without changing the form thereof, and a desorption process whereby the adsorbed material can be desorbed from the active carbon to thereby enable the reuse of the active carbon and the adsorbed material. In the aforesaid processes, a solution containing a fluorocarboxylic acid having an ether bond is contacted with active carbon and thus the active carbon is allowed to adsorb the fluorocarboxylic acid, to thereby give a solution having a small fluorocarboxylic acid content. Then, the active carbon having adsorbed the fluorocarboxylic acid is heated to thereby desorbs the fluorocarboxylic acid from the active carbon.

Method for adsorbing fluorocarboxylic acid having ether bond and method for collecting same

A process for preparing a fluorocarboxylic acid, which includes a dehydration step of removing from a mixture containing a fluorocarboxylic acid and water at least a part of the water to obtain a dehydrated fluorocarboxylic acid solution, and a purification step of purifying the dehydrated fluorocarboxylic acid solution.

Process for preparing fluorocarboxylic acid

There is provided a method for separating and collecting at least alcohol with a high purity from an azeotropic mixture of olefin and alcohol. The method conducts the following steps: an azeotropic mixture crystallization step of subjecting an azeotropic mixture of alcohol and olefin represented by the formula: RfCH&#x2550;CH[wherein Rf represents a linear perfluoroalkyl group having 1 to 10 carbon atoms] to a crystallization procedure to separate the mixture into an olefin portion having a higher olefin concentration than that of the original azeotropic mixture and an alcohol portion having a higher alcohol concentration than that of the original azeotropic mixture; and an alcohol purification step of subjecting the separated alcohol portion to either a crystallization procedure or a distillation procedure to separate the alcohol portion into a low-alcohol portion having a lower alcohol concentration than that of the original alcohol portion and a high-alcohol portion having a higher alcohol concentration than that of the original alcohol portion, and thereby collecting alcohol as the high-alcohol portion.

Method for separation of olefin-alcohol azeotropic mixture

In a first sulfation step, 2-perfluoroalkylethyl iodide is brought into contact with fuming sulfuric acid to obtain a reaction mixture comprising 2-perfluoroalkylethyl sulfate and bis(2-perfluoroalkylethyl)sulfate. Then, in a first hydrolysis step, 2-perfluoroalkylethyl sulfate produced in the first sulfation step is hydrolyzed to obtain a reaction mixture comprising 2-perfluoroalkylethyl alcohol. In a second sulfation step, bis(2-perfluoroalkylethyl)sulfate produced in the first sulfation step is brought into contact with fuming sulfuric acid to obtain a reaction mixture comprising 2-perfluoroalkylethyl sulfate. Then, in a second hydrolysis step, 2-perfluoroalkylethyl sulfate produced in the second sulfation step is hydrolyzed to obtain a reaction mixture comprising 2-perfluoroalkylethyl alcohol. According to such procedures, 2-perfluoroalkylethyl alcohol can be obtained in a high yield.

Process for producing 2-perfluoroalkylethyl alcohol

Processes for producing a fluoromonomer from a fluoropolymer, among which one that can be carried out more simply is a process wherein thermal decomposition of a fluoropolymer is preformed by means of a rotary kiln () so as to produce a fluoromonomer, the process comprising feeding a fluoropolymer and steam () into a rotary kiln and heating the fluoropolymer.

Process for producing fluoromonomer

A fluorocarboxylic acid preparation process which includes hydrolyzing fluorocarboxylic acid fluoride in the presence of an aqueous sulfuric acid solution to form a reaction product containing a fluorocarboxylic acid and hydrogen fluoride (present as hydrofluoric acid); and removing at least some of the hydrogen fluoride from the reaction product by washing the reaction production with aqueous sulfuric acid solution. The hydrolyzing and washing are carried out at a temperature at which the fluorocarboxylic acid is a liquid.

Process for preparing fluorocarboxylic acids

A fluorocarboxylic acid preparation process continuously carries out acidification reaction treatment and washing treatment, and includes subjecting a fluorocarboxylate-containing aqueous solution to acidification reaction treatment in the presence of sulfuric acid so as to form a sulfate-containing fluorocarboxylic acid phase; and subjecting the fluorocarboxylic acid phase to washing treatment using an aqueous sulfuric acid solution.

Upon recovering a fluorochemical surfactant from a fluorochemical-containing aqueous solution, there is provided a method for recovering the fluorochemical surfactant from the aqueous solution containing the surfactant. In the method, the fluorochemical surfactant is recovered by subjecting the aqueous solution containing the fluorochemical surfactant to a filtration treatment step with a reverse osmosis membrane so as to obtain from the aqueous solution, a concentrated aqueous solution in which the concentration of the fluorochemical surfactant is increased.

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Settsu, Japan

Takuya Ichida