JPS6012910B2 - Fluorination catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel fluorination catalyst, and more specifically to a novel fluorination catalyst, and more specifically to a method for reacting chloroaliphatic hydrocarbons and chlorofluoroaliphatic hydrocarbons with hydrogen fluoride to eliminate chlorine in these compounds. This invention relates to a novel catalyst for fluorination reactions with fluorine substitution.

Until now, various catalysts for such fluorination reactions have been known, among them chromium (m) compounds, such as chromium (m) chloride, chromium fluoride (m), and chromium fluoride reacted with oxygen, or Chromium oxyfluoride, which is obtained by reacting hydrogen fluoride with chromium oxide or chromium hydroxide, is well known.

However, these known catalysts leave room for improvement in terms of conversion. An object of the present invention is to provide a fluorination catalyst with an excellent conversion rate.

This objective is achieved by a fluorination catalyst prepared by supporting a mixture of chromium (m) chloride hexahydrate and ammonium chromate on activated carbon, treating it with ammonia and heating at 220-300°C.

As a result, for example, 1.112-trichlor 1.2
・When fluorinating 2-trifluoroethane, the conversion rate was 66.7% with chromium chloride (m) treated with hydrogen fluoride, but the conversion rate of 95% or more was obtained with the catalyst of the present invention. It will be done.

The chromium (m) chloride hexahydrate used in the preparation of the catalyst of the present invention may be any commercially available chromium(m) chloride hexahydrate.

Moreover, commercially available ammonium chromate can also be used.

Therefore, in order to support activated carbon with chromium chloride hexahydrate and ammonium chromate, the activated carbon may be soaked in an aqueous solution containing both of them and dried.

There is no particular restriction on the amount of both of these supported, and the smaller the amount, the more the amount of catalyst used in the fluorination reaction may be increased, and the space velocity of the reactants may be reduced. Usually, 10 to 5% by weight based on the weight of activated carbon is suitable. The appropriate ratio of the two used is 0.5 to 5 parts by weight of ammonium chromate to 5 parts by weight of chromium chloride (m) hexahydrate.

This is because the conversion rate increases with the addition of a small amount of ammonium chromate to chromium chloride (m) hexahydride, but the conversion rate does not increase further even when the amount added is increased. be. Next, the activated carbon carrying chromium (m) chloride hexahydrate and ammonium chromate is treated with ammonia.

This can be accomplished by passing ammonia gas through the activated carbon layer at room temperature (around 260 ℃). The process ends when the hot spot passes through the activated carbon layer. The ammoniated activated carbon is then heated.

Heating is performed at 220 to 300 oo. When it is lower than 220oo, the activity is low, and even when it is higher than 300oo, the activity is not very high.

Preferably, in order to avoid sudden changes to the ammonia-treated activated carbon, the temperature should first be around 20,000 (180 to 220
°C) and then in a stream of inert gas such as nitrogen gas at 270°C.
oo (250 to 300 qo), and desirably further heated at 300 to 500 oo in a hydrogen fluoride gas stream. The fluorination reaction that the catalyst of the present invention acts on has a carbon number of 1
This is a chlorine fluorine substitution reaction in which hydrogen fluoride is reacted with ~4 chloroalkane or chlorofluoroalkane or a chloroalkene or chlorofluoroalkene having 2 to 4 carbon atoms.

These reactions are carried out under various conditions depending on the ease of substitution of each compound and the number of substituted atoms, but usually the reaction temperature is 100 to 500 qo, the reaction pressure is 1 to 10 atm, and the space velocity is 100 to 400 qo. In skin r-1, the ratio of hydrogen fluoride to 1 mole of starting material is 0.5 to 20 moles.

Next, the present invention will be explained in more detail by showing Examples and Comparative Examples.

Example 1 After evacuating 4 to 6 mesh granular activated carbon 50' in a container, chromium chloride (m) hexahydrate C par 3 was added to it.
・Aqueous solution of Hoso 20 and ammonium chromate (NH4
) An aqueous solution prepared by mixing an aqueous solution of 2CrQ and having a composition of 2010 parts of CrC13, 48 parts of (NH4)2C, and 42 parts of water was added and left to stand for 3 minutes.

The granules were collected, dried at 90° C. for 1 hour, and then filled into a 1-inch Hastelloy G pipe. After the hot spot passes through the filling zone through ammonia gas at room temperature (290°C), it is first heated to 22,000°C in a nitrogen stream and then heated at that temperature for 1. The temperature was maintained for an hour, then the temperature was raised to 270°C, maintained at that temperature for 1 hour, and finally allowed to cool to 180°C.

Thereafter, at this temperature, hydrogen fluoride was added to the nitrogen stream at a rate of 200 m/min and treated for 4 minutes.
The sample was treated with hydrogen fluoride for 2 hours at 450°C and for 2 hours at 450°C. Using the catalyst thus obtained, a fluorination reaction of trichlorotrifluoroethane was carried out.

The reaction conditions were: reaction temperature: 370°C, reaction pressure: atmospheric pressure, H
The F/CC12FCCIF2 (molar ratio) was 8 and the space velocity was 45 skin r-1. The exhaust gas was sequentially passed through a water washing tower, an alkali washing tower, and a calcium chloride drying tower, and was collected in a dry ice-acetone cold trap.

The gas after passing through the calcium chloride drying tower was analyzed by gas chromatography.

The results were as follows. Conversion rate of CC12FCCIF2 97.8% Selectivity of CCIF2CCIF2
90.2% Examples 2 and 3 In Example 1, CrC13・mother LO and (NH4)2・C4
A catalyst was prepared using the same procedure except that the amount of 2 used was as shown in Table 1.

Using this catalyst, the fluorination reaction of trichlorotrifluoroethane was carried out under the same reaction conditions and method as in Example 1.

The results are shown in Table 2.

Table 1 Table 2 Comparative Examples 1 and 2 A catalyst was prepared in the same manner as in Example 1 using an aqueous solution having the following composition.

Note that in Comparative Example 1, no treatment was performed in which ammonia gas was passed through. Comparative example of composition of aqueous solution 1 C℃ 13・Mother's day 20 18 ta water
Comparative Example 2 (N is) 2Cr04 9T water
A fluorination reaction of trichlorotrifluoretaso was carried out using this catalyst under the same reaction conditions and method as in Example 1.

The results are shown in Table 3.

Table 3 Examples 4 to 6 Using a catalyst prepared in the same manner as in Example 1, the starting materials shown in Table 4 were reacted with hydrogen fluoride to produce target substances.

The reaction conditions and results are also shown in Table 4. Table 4

Claims (1)

[Scope of Claims] 1. A carbon number 1, which is prepared by supporting a mixture of chromium (III) chloride hexahydrate and ammonium chromate on activated carbon, treating it with ammonia, and heating it at 220 to 300°C. A fluorination catalyst for a fluorine substitution reaction of chlorine, which reacts hydrogen fluoride with a chloroalkane or chlorofluoroalkane having 4 to 4 carbon atoms or a chloroalkene or chlorofluoroalkene having 2 to 4 carbon atoms. 2. The fluorination catalyst according to claim 1, wherein the ratio of chromium (III) chloride hexahydrate and ammonium chromate is 5 parts by weight of the former and 0.5 to 5 parts by weight of the latter. 3. The fluorination catalyst according to claim 1 or 2, wherein the total supported amount of chromium (III) chloride hexahydrate and ammonium chromate is 10 to 50% by weight of the activated carbon.