JPH09227443A - Production of trifluoroacetic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce trifluoroacetic acid in high yield by reacting 1,1,1- trichloro-2,2,2-trifluoroethane (R1134a for short) with water. SOLUTION: R1134a is reacted with water in the presence of a copper-based catalyst (e.g. copper chloride) and a catalyst of the groups VIII to X of the periodic table (e.g. ruthenium or iron chloride) by a vapor-phase reaction at 200-400 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to 1,1,1-trichloro-2,2,2-trifluoroethane CF ₃ CCl ₃
(Hereinafter, abbreviated as R113a) CF reacting with water in the presence of a specific catalyst, CF trifluoroacetic acid
_{The present} invention relates to a method for producing ₃ COOH (hereinafter abbreviated as TFA). TFA and its derivatives are compounds useful as raw materials for manufacturing pharmaceuticals and agricultural chemicals.

[0002]

2. Description of the Related Art As a manufacturing method of TFA, R113a is used.
There is known a method of hydrolyzing bisphenol in the presence of an iron chloride catalyst or a copper chloride catalyst (JP-A-60-197635). However, the hydrolysis method in the presence of an iron chloride catalyst or a copper chloride catalyst is not industrially advantageous because the activity of the catalyst is not sufficient and the amount of recycled raw materials increases.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks found in the conventional methods and to provide an industrial production method of TFA.

[0004]

The present invention is a method for producing trifluoroacetic acid, which comprises reacting R113a with water in the presence of a copper catalyst and a Group 8-10 catalyst of the periodic table.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is important to use a copper-based catalyst in combination with a group 8-10 catalyst of the periodic table (former group VIII of the periodic table). The copper-based catalyst is a catalyst containing copper or a copper compound as a main component. Examples of the copper compound include copper salts such as sulfates, copper halides, and copper oxides. As the copper-based catalyst, a catalyst containing a copper compound as a main component is preferable, and a copper halide is preferable from the viewpoint of easy catalyst preparation, and copper chloride is particularly preferable.

The catalysts of Groups 8 to 10 of the periodic table are iron, cobalt, nickel, ruthenium, rhodium, palladium,
It is a catalyst whose main component is a metal (zero-valent metal) selected from osmium, iridium and platinum or a compound of these metals.

The zero-valent metal is preferably iron, cobalt, nickel, ruthenium, rhodium, palladium or the like. Examples of the metal compound include sulfates such as iron, cobalt, nickel, ruthenium, rhodium and palladium,
Salts of halides such as iron, cobalt, nickel, ruthenium, rhodium and palladium are preferred. Periodic table No. 8
As the group-10 catalyst, iron halides such as zero-valent ruthenium and iron chloride are excellent in activity and are particularly preferable.

In the present invention, the catalyst is preferably used by supporting it on a carrier. As the carrier, alumina, zirconia, activated carbon and the like are preferable, and activated carbon is particularly preferable because the activity of the catalyst is high.

As a method of supporting the catalyst, a conventionally known method is used. For example, when the catalysts to be supported are copper chloride and iron chloride, the two metal salts can be supported on the carrier simultaneously or sequentially by the impregnation method. In the case of copper chloride and zero-valent ruthenium, for example, it is preferable that zero-valent ruthenium is supported on a carrier and then copper chloride is supported by an impregnation method.

The loading amount of the copper-based catalyst and the Group 8 to 10 catalyst of the periodic table and the loading ratio of both are not limited. The supported amount is preferably equal to or lower than the supporting ability of the carrier, and if it exceeds this amount, the excess catalyst will fall off from the carrier when TFA is produced, which is uneconomical. The supported amount is not limited as long as it is not more than the supporting ability, but if it is too small, sufficient reaction activity cannot be obtained.
The preferred catalyst loading is 0.1 to 50% by weight, respectively. As a supported amount for achieving a preferable reaction rate,
For example, 10 to 30% by weight is suitable for the copper-based catalyst, 1 to 5% by weight for the ruthenium catalyst, and 10 to 30% by weight for the iron-based catalyst.

The reaction temperature in the present invention is 200 to 40.
The range of 0 ° C is preferable, and 250 to 300 ° C is particularly preferable. If it is lower than 200 ° C, the reactivity is low, and if it exceeds 400 ° C, the selectivity of the reaction is lowered, which is not preferable.

In order to obtain TFA, stoichiometrically, 2 mol of water is required for 1 mol of R113a, and the molar ratio of water to R113a used for the reaction is preferably 2 or more. A more preferable molar ratio is a value of 2-5. If the amount of water supplied is too small, the conversion rate of R113a will be small, and if it is too large, the TFA obtained will be a low-concentration aqueous hydrochloric acid solution, making it difficult to isolate TFA, which is not preferable.

The reaction can be carried out in the liquid phase or the gas phase. However, the preferred reaction mode of the present invention is the use of R vaporized in the preheating layer.
This is a gas phase reaction in which 113a and water are introduced into a reactor filled with a catalyst to carry out a reaction. The reason why the gas phase reaction is preferable is that R113a and water can be brought into contact with the solid catalyst efficiently and continuously, and that high pressure in the liquid phase reaction is not required. The reaction pressure can be either normal pressure or increased pressure.

The reaction time, that is, the time (contact time) for which the raw material stays in the catalyst-packed bed is not limited, but is preferably 5 to 60 seconds, particularly 10 to 40 seconds in consideration of the limitation on the reactor.

[0015]

[Examples] Examples (Examples 1 and 2) and comparative examples (Examples 3 and 4) will be specifically described below, but the present invention is not limited thereto. In Table 1, the supply molar ratio is R
The molar ratio of water to 113a and the conversion rate are R1 supplied.
The conversion rate and selectivity of 13a are the selectivity of TFA with respect to the consumed R113a.

[Example 1] Ferric chloride 20 per 100 g of activated carbon
g and 18 g of cupric chloride were supported by the impregnation method, 120 ml of the catalyst obtained was charged into the reactor, and R113a and water were introduced through the vaporizer at a constant supply molar ratio to carry out the reaction. The reaction product was identified and quantified by gas chromatography. The results are shown in Table 1.

Example 2 Using a catalyst in which 2 g of ruthenium chloride was carried on 100 g of activated carbon by an impregnation method, dried and then reduced with hydrogen, 18 g of cupric chloride was further carried by an impregnation method. A reaction similar to that in Example 1 was performed under the respective reaction conditions shown in Table 1. The results are shown in Table 1.

[Examples 3 to 4] Using a catalyst prepared by impregnating 100 g of activated carbon with 18 g of cupric chloride or 20 g of ferric chloride by the impregnation method, the same reaction as in Example 1 was carried out under the respective reaction conditions shown in Table 1. It was The results are shown in Table 1.

From Examples 1 and 3, it can be seen that the activity of the catalyst supporting cupric chloride and ferric chloride is higher than that of the ferric chloride alone catalyst. From Examples 2 and 4, it can be seen that the activity of the catalyst supporting cupric chloride and metallic ruthenium is higher than that of the cupric chloride alone catalyst.

[0020]

[Table 1]

[0021]

According to the present invention, in the reaction of R113a and water, a coexisting system of a copper-based catalyst and a Group 8-10 catalyst of the periodic table exhibits excellent catalytic performance.

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Claims (2)

[Claims] 1. A method of reacting 1,1,1-trichloro-2,2,2-trifluoroethane with water in the presence of a copper-based catalyst and a group 8-10 catalyst of the periodic table. Method for producing fluoroacetic acid. 2. The method for producing trifluoroacetic acid according to claim 1, wherein the catalyst is supported on activated carbon.