JPS6052132B2 - Method for producing perfluoro-2-butene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing perfluoro-2-butene, and more particularly to a method for producing perfluoro-2-butene by rearranging perfluoro-1-butene to perfluoro-2-butene using a specific catalyst. Regarding how to.

Perfluoro-2-butene is useful as a propellant or polymeric monomer, such as a modifying monomer in fluorohydrocarbon polymers, and as an intermediate, such as by oxidation to trifluoroacetic acid fluoride, which It is useful as an intermediate in the production of trifluoroacetic acid.

Perfluoro-2-butene is used in the production of tetrafluoroethylene by the thermal decomposition reaction of chlorodifluoromethane or in the production of hexafluoropropene by the thermal decomposition reaction of tetrafluoroethylene.
-It is produced as a by-product together with C4 aliphatic perfluorohydrocarbons such as butene, but it is difficult to isolate it from these.

That is, perfluoroisobutene can be isolated from the other three components using caustic or lower alcohol, and of the remaining three components, perfluoro-1-butene and barfluoro-2-butene can be isolated by reacting with elemental silium. Can be separated from fluorocyclobutane.

However, perfluoro-1-butene and perfluoro-2
-Butenes are extremely difficult to separate, both as such and as oxalides. This is because the melting points and boiling points of both are similar. Therefore, converting one component of a mixture of the two into the other is an important issue in utilizing them.

Conventionally, perfluoro-1-butene perfluoro-2
The rearrangement reaction to -butene is known to occur in a solvent in the presence of a catalyst such as potassium fluoride or cesium fluoride.

This method requires the use of a solvent, and these catalysts tend to absorb water, which poisons the catalyst, making them difficult to handle and resulting in high costs. The present invention aims to eliminate these drawbacks, and its gist consists in a method for producing perfluoro-2-butene by contacting perfluoro-1-butene with aluminum oxide or nickel oxide.

According to the present invention, there is no need to use a solvent, the selectivity is high, the catalyst is excellent in stability, and the target product can be obtained efficiently and stably.

Aluminum oxide used as a catalyst in the present invention is not particularly limited, but activated alumina is preferred.

Moreover, silica alumina can also be used. Nickel oxide can also be used as a commercially available product.

During the contact, the starting material, perfluoro-1-butene, may be diluted with an appropriate gas, such as an inert gas such as nitrogen or carbon dioxide.

The temperature condition during contact is 150 to 400°C, preferably 2
00~300℃. When the temperature is lower than 150°C, the rate of change is low, while when it is higher than 400°C, the selectivity is low.

As can be understood from the fact that the reaction according to the present invention is a rearrangement reaction, there is almost no need to take pressure conditions into consideration, but it is usually 0.1 to 10 atm, preferably 0.1 atm.
A pressure of 5 to 3 atmospheres or total pressure (if a diluent gas is present) is employed.

The space velocity depends on other conditions, especially temperature, and as with other general reactions, it is best to set it high at high temperatures and low at low temperatures. Generally, 30 to 1,000 F1r1 is preferred. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Granular activated alumina (NeObead C-4 manufactured by Mizusawa Chemical Co., Ltd.)
) was pulverized to 20 to 50 mesh, and 400
Heated at ℃ for 5 hours.

Heated activated alumina 5y length 0.5m11 inner diameter 3
TfrJn was filled into a glass reaction tube and heated to 200°C or 250°C in an electric constant temperature bath.
Butene was passed through at atmospheric pressure and a space velocity of 100F1r1.

The exhaust gas was analyzed by gas chromatography. The results are shown in Table 1. Example 2 Particle size 2.3-4.7T! A 1-inch Pyrex glass tube was filled with 40y of R1n granular alumina (NeObead C-4 manufactured by Mizusawa Chemical Co., Ltd.) and heated at 400° C. for 5 hours in an electric furnace in a nitrogen stream to undergo a reaction.

Perfluoro-1-butene was passed through the glass tube filled with the catalyst at 250°C, atmospheric pressure, and space velocity of 120F1r-1. The exhaust gas was analyzed by gas chromatography and the results shown in Table 2 were obtained. Example 3 Commercially available nickel oxide (20-50 mesh) was heated at 400° C. for 5 hours in a nitrogen stream.

Heated nickel oxide 3.8y, length 0.5n1, inner diameter 3T! The reaction tube was filled into an R1n glass reaction tube, heated to 200°C, 250'C or 270°C in an electric constant temperature bath, and perfluoro-1-butene was passed through it at atmospheric pressure and a space velocity of 100F1r-1.

The exhaust gas was analyzed by gas chromatography and the results shown in Table 3 were obtained. Example 4 Aqueous ammonia was added to a commercially available aqueous solution of nickel chloride (NiCI2-6H20), the resulting precipitate was separated, and 100%
After drying at ℃ for 25A, it was formed into pellets with a length of 2Tfn1 and a diameter of 3mm.

The pellets were heated at 500° C. for 5 hours in a nitrogen stream. The heated catalyst pellets (50y) were packed into a 1-inch Pyrex glass reaction tube, heated in an electric furnace at 300°C in a nitrogen stream for 5 hours, and then perfluorinated at 250°C, atmospheric pressure, and a space velocity of 80F1r-1. passed through butene.

The exhaust gas was analyzed by gas chromatography. As a result of analysis, the conversion rate of perfluoro-1-butene was 98%, and the selectivity of perfluoro-2-butene was 95%. Example 5 In Example 1, a mixture of perfluoro-1-butene and perfluoro-2-butene (87.0:13.0 (mole ratio)) was used as the starting material instead of perfluoro-1-butene, and the reaction temperature was only 250°C. Except for this, the same procedure was repeated to obtain the results shown in Table 4.

Example 6 In Example 3, perfluoro-1-butene and perfluoro-2 were used instead of perfluoro-1-butene.
The same procedure was repeated except that an 87.0:13.0 (molar ratio) mixture of -butenes was used as the starting material and the reaction temperature was only 270° C. to obtain the results shown in Table 5.

Example 7 Granular silica alumina (
SiO2:Al2O3=60:40 (weight ratio)) 35f
The mixture was filled into a Pyrex glass tube having a length of 1 m and an inner diameter of 22 mm, and heated at 400°C for 3 hours in a nitrogen stream.

Thereafter, it was cooled to 250°C, and at that temperature, perfluoro-1-butene was passed through it at a space velocity of 100F1r-1. The exhaust gas was analyzed by gas chromatography and the results shown in Table 6 were obtained. Comparative Example 1 Commercially available antimony (V) oxide powder (20 to 50 mesh) was heated at 400° C. for 5 hours in a nitrogen stream.

As in Example 5, a glass tube was filled with heated antimony (V) oxide, heated to 270° C., and a mixture of perfluoro-1-butene and perfluoro-2-butene was passed through the tube.

Similarly, the exhaust gas was analyzed and the results shown in Table 7 were obtained. Comparative Example 2 Commercially available cobalt oxide powder (20-50 mesh)
was heated at 400° C. for 5 hours in a nitrogen stream.

Claims (1)

[Scope of Claims] 1. A method for producing perfluoro-2-butene, which comprises contacting perfluoro-1-butene with aluminum oxide or nickel oxide to obtain perfluoro-2-butene. 2. The manufacturing method according to claim 1, wherein the contact temperature is 150 to 400°C.