JPH05972A - Method for purifying saturated halogenated hydrocarbon - Google Patents

Abstract

PURPOSE:To reduce concentration of contained unsaturated impurities in a saturated halogenated hydrocarbon by minimizing the loss of the saturated halogenated hydrocarbon in purifying the saturated halogenated hydrocarbon used as foaming agents, refrigerants, detergents, etc. CONSTITUTION:A saturated halogenated hydrocarbon such as 2,2-dichloro-1,1,1- trifluoroethane or 1,1,1,2-tetrafluoroethane containing unsaturated impurities is allowed to react with ozone to reduce the concentrations of the contained unsaturated impurities.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for purifying saturated halogenated hydrocarbons. In particular, the present invention relates to a purification method for substantially reducing chain or cyclic halogenated hydrocarbons (hereinafter abbreviated as unsaturated impurities) having a double bond and / or a triple bond contained in a saturated halogenated hydrocarbon.

[0002]

2. Description of the Related Art Saturated halogenated hydrocarbons are expected to be used as foaming agents, refrigerants, cleaning agents, etc. Many of these are gases and liquids which are inert and have low toxicity at normal temperature and pressure, and are useful. In particular, hydrogen-containing saturated halogenated hydrocarbons have a very low possibility of depleting the ozone layer, and are therefore attracting attention as substitutes for hydrogen-free halogenated hydrocarbons used in the conventional market such as specified CFCs.

In the production of saturated halogenated hydrocarbons,
Undesirable unsaturated impurities are often also by-produced. Unsaturated impurities contained in these saturated halogenated hydrocarbons are usually many compounds having higher toxicity than saturated halogenated hydrocarbons, and it is necessary to remove or reduce the content. General methods for reducing the content of unsaturated impurities include a distillation method and an adsorption removal method.

Further, in order to separate a saturated halogenated hydrocarbon and an unsaturated impurity, which are generally similar in physical properties, to a certain extent by general distillation, and then a method involving a chemical reaction is combined to leave the residue. The method of removing unsaturated impurities is preferable, and various proposals have been made in the past. According to USP2,999,855, USP4,129,603 and the like, an oxidation treatment method using an aqueous potassium permanganate solution is effective as a method for removing the residual unsaturated impurities.

In EP370,688, there is an example in which a metal oxide such as hopcalite is used for decomposition treatment of unsaturated impurities in a gas phase.

[0006]

The method by distillation is expensive because it is necessary to increase the number of distillation stages in the distillation column to separate unsaturated impurities having a close boiling point. On the other hand, it is generally inefficient, such as not being effective. The method by adsorption removal cannot be adopted unless the difference in molecular size, adsorption characteristics, etc. clearly appears.
Limited application.

The method using an aqueous solution of potassium permanganate is that potassium permanganate is relatively expensive, that it is necessary to dispose of the manganese compound which is a heavy metal, and saturated halogenated hydrocarbons are in the aqueous solution of potassium permanganate. There is a problem from an industrial point of view that it is distributed to and lost. In addition, the method of EP370,688 is not sufficient in terms of activity, such that the time until breakthrough of the metal oxide is as short as 204 hours at the longest and unsaturated impurities for the purpose of removal remain after the reaction.

An object of the present invention is to provide a new and effective purification method for efficiently reducing the content of unsaturated impurities contained in saturated halogenated hydrocarbons. Yet another object is to provide such a method which minimizes the loss of the purified saturated halogenated hydrocarbon main component and reduces the content concentration of unsaturated impurities.

[0009]

Although ozone oxidation of a fluorine-containing organic compound has been conventionally known, there is no example applied to the purification of a saturated halogenated hydrocarbon. Therefore, as a result of intensive studies to achieve the above-mentioned object, the present inventors brought ozone into contact with a saturated halogenated hydrocarbon containing an unsaturated impurity, and decomposed the impurity via an ozonide.
I found that it can be removed.

That is, the present ozone oxidation minimizes the loss of the saturated halogenated hydrocarbon, selectively decomposes the unsaturated impurities contained in the saturated halogenated hydrocarbon, and the saturated impurities are contained in the saturated halogenated hydrocarbon. The inventors have found that the content of unsaturated impurities can be efficiently reduced and have provided the present invention.

The details of the present invention will be described below with reference to examples. According to the method of the present invention, a saturated halogenated hydrocarbon containing an unsaturated impurity (general formula C _n H _x Cl _y F _z Br _w : in the case of a chain, 1 ≦ n, x + y + z + w = 2n + 2, 0 ≤ x <2n + 2, 0 ≤
y ≤ 2n + 2, 0 ≤ z ≤ 2n + 2, 0 ≤ w ≤ 2n + 2, 3 k when having k cyclic groups in the molecule, 3 ≤ n, x + y + z + w = 2n + 2- 2k, 0
≤x <2n + 2-2k, 0 ≤y 2n + 2-2k, 0 ≤z ≤2n + 2-2k,
0 ≤ w ≤ 2n + 2-2k) and ozone
A method for purifying saturated halogenated hydrocarbons, characterized in that saturated halogenated hydrocarbons having a reduced unsaturated impurity content are obtained.

Among the saturated halogenated hydrocarbons to be purified, hydrocarbons having at least one hydrogen and at least one fluorine (general formula C _n H _x Cl _y F _z Br
_w : For chain, 1 ≤ n, x + y + z + w = 2n + 2, 1 ≤ x <2n +
2, 0 ≤ y ≤ 2n + 2, 1 ≤ z ≤ 2n + 2, 0 ≤ w ≤ 2n + 2, 3 k ≤ n, x + y + z + w = when the molecule has k cyclic groups 2n + 2
-2k, 1 ≤x 2n + 2-2k, 0 ≤y ≤2n + 2-2k, 1 ≤z ≤2n
+ 2-2k, 0 ≤w ≤2n + 2-2k) is important as a substitute candidate for a specific CFC.

Examples of saturated halogenated hydrocarbons include carbon tetrachloride (R-10), trichlorofluoromethane (R-11), dichlorodifluoromethane (R-12), chlorotrifluoromethane (R-13) and tetrafluoro. Methane (R-14), chloroform
(R-20), dichlorofluoromethane (R-21), chlorodifluoromethane (R-22), trifluoromethane (R-23), methylene chloride (R-30), methyl chloride (R-40), bromotrichloro Methane (R-10B1), bromodichlorofluoromethane (R-11B
1), bromochlorodifluoromethane (R-12B1), bromodifluoromethane (R-22B1), bromotrifluoromethane (R
-13B1), C ₁ series such as iodotrifluoromethane, pentachlorofluoroethane (R-111), tetrachloro-1,2-difluoroethane (R-112), tetrachloro-1,1-difluoroethane (R-112a) , 1,1,2-Trichloro-trifluoroethane (R-113), 1,1,1-Trichloro-trifluoroethane
(R-113a), 1,2-dichloro-tetrafluoroethane (R-11
4), 1,1, -dichloro-tetrafluoroethane (R-114
a), chloropentafluoroethane (R-115), 1,2,2-trichloro-1,1-difluoroethane (R-122), 1,1,2-trichloro-1,2-difluoroethane (R-122a) , 1,1,1-trichloro-2,2-difluoroethane (R-122b), 2,2-dichloro-1,
1,1-trifluoroethane (R-123), 1,2-dichloro-1,1,
2-trifluoroethane (R-123a), 1,1-dichloro-1,2,2-
Trifluoroethane (R-123b), chloro-1,1,1,2-tetrafluoroethane (R-124), 1-chloro-1,1,2,2-tetrafluoroethane (R-124a), penta Fluoroethane (R-12
5), 1,1,2,2-tetrachloroethane (R-130), 1,1,1,2-
Tetrachloroethane (R-130a), 1,2-dichloro-1,2-difluoroethane (R-132), 1,1-dichloro-2,2-difluoroethane (R-132a), 1,2-dichloro-1, 1-difluoroethane
(R-132b), 1,1-dichloro-1,2-difluoroethane (R-132
c), 1-chloro-1,2,2-trifluoroethane (R-133), 2-
Chloro-1,1,1-trifluoroethane (R-133a), 1,1,2,2-
Tetrafluoroethane (R-134), 1,1,1,2-tetrafluoroethane (R-134a), 1,1,2-trichloroethane (R-140),
1,1,1-Trichloroethane (R-140a), 1,2-Dichloro-1-fluoroethane (R-141), 1,1-Dichloro-2-fluoroethane (R-141a), 1,1-Dichloro -1-Fluoroethane (R-141
b), 2-chloro-1,1-difluoroethane (R-142), 1-chloro-1,2-difluoroethane (R-142a), 1-chloro-1,1-difluoroethane (R-142b), 1, 1,2-trifluoroethane (R
-143), 1,1,1-trifluoroethane (R-143a), 1,2-dibromo-tetrafluoroethane (R-114B2), 1-chloro-2-
C ₂ system such as iodotetrafluoroethane, octafluoropropane (R-218), 1,1,1-trichloro-2,2,3,3,3-pentafluoropropane (R-215cb), 1,1, 3-trichloro-
Trichloropentafluoropropane (R-215) such as 1,2,2,3,3-pentafluoropropane (R-215ca), 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R-225cb)
, 3,3-dichloro-1,1,1,2,2-pentafluoropropane
(R-225ca) such as dichloropentafluoropropane (R-
225) type, tetrachlorotetrafluoropropane (R-224)
, Chain saturated halogenated hydrocarbons represented by C ₃ series such as 1-chloro-3-iodoperfluoropropane and 1-iodoperfluoropropane, and hexafluorocyclopropane (C-216), 1 , 1,2,2-Tetrachlorotetrafluorocyclobutane (C-314), 1,2-dichlorohexafluorobutane (C-316), octafluorocyclobutane (C-31)
8), 1,2,2-trichloro-3,3,4,4-tetrafluorocyclobutane (C-324), 1,1,2-trifluoro-2-chlorocyclobutane (C-344), 1-chloro -1,2,2-Tetrafluorocyclobutane (C-353), 1,1,2,2-Tetrafluorocyclobutane (C-354), cyclic saturated halogenated hydrocarbons such as perfluoromethylcyclopropane Is mentioned.

Examples of unsaturated impurities that are ozone-oxidized during purification include tetrafluoroethylene (R-1114), chlorotrifluoroethylene (R-1113), 1,1-dichlorodifluoroethylene (R-1112a), cis- 1,2-dichlorodifluoroethylene (R-1112), trans-1,2-dichlorodifluoroethylene (R-1112), trichlorofluoroethylene (R-1
111), tetrachloroethylene (R-1110), trifluoroethylene (R-1123), 1-chloro-2,2-difluoroethylene (R
-1122), 1,1-dichloro-2-fluoroethylene (R-1121a)
, 1,2-dichloro-1-fluoroethylene (R-1121), trichloroethylene (R-1120), 1,1-difluoroethylene (R-1
132a), 1,2-difluoroethylene (R-1132), 1-chloro-1
-Fluoroethylene (R-1131a), cis-1-chloro-2-fluoroethylene (R-1131), trans-1-chloro-2-fluoroethylene (R-1131), 1,1-dichloroethylene (R-1130
a), cis-1,2-dichloroethylene (R-1130), trans-
1,2-Chloroethylene (R-1130), Fluoroethylene (R-11
41), chloroethylene (R-1140), ethylene (R-1150), 1-
C ₂ series such as bromo-2,2-difluoroethylene (R-1122B1), bromotrifluoroethylene (R-1113B1) and 1,1-dibromodifluoroethylene (R-1121aB2), hexafluoropropene (R-1216) , 2-chloropentafluoropropene (R-1
215xc), 1,1-dichlorotetrafluoropropene (R-1214y
a), 1,3-dichlorotetrafluoropropene-E (R-1214y
b), 1,3-dichlorotetrafluoropropene-Z (R-1214y
b), 1,1,2-trichlorotrifluoropropene (R-1213x
a), 1,1,3,3,3-pentafluoropropene (R-1225zc), 1,
2-dichloro-3,3,3-trifluoropropene (R-1223xd),
3,3,3-trifluoropropene (R-1243zf), 2- tetrafluoropropene (R-1261yf) C ₃ system, such as, octafluoro-2-ene
(R-1318my), 2-chloroheptafluorobutene-2 (R-1317m
xy), 2,3-dichlorohexafluorobutene-2 (R-1316mx
x), 2-chloro-1,1,1,4,4,4-hexafluorobutene-2
(R-1326mxz), 1,1,1,4,4,4-hexafluorobutene-2 (R-
1336mzz), 2-trifluoromethyl-pentafluoropropene, 4-chloro-1,1,2,3,3,4,4-pentafluorobutene-2,2-bromo-1,1,1,4,4 , 4-hexafluorobutene-
2,2-Bromo-3-chloro-1,1,1,4,4,4-hexafluorobutene-2,2,3-dibromo-1,1,1,4,4,4-hexafluorobutene- 2, C such as perfluorobutyne-2, hexafluorobutadiene and 1,2-dichlorotetrafluorocyclobutene
C of ₄ series, chlorooctafluoropentene, dichlorooctafluoropentene, chlorononafluoropentene, etc.
C ₆ such as ₅ series, dichlorodecafluorohexene, chloroundecafluorohexene, chlorodecafluorohexene, undecafluorohexene, decafluorohexene, etc.
System. Further, when present, two or more of the above unsaturated impurities may be contained at the same time, including cis and trans isomers thereof.

Most of the unsaturated impurities contained in the saturated halogenated hydrocarbon to be purified are separated by a method such as ordinary distillation, and the unsaturated impurity content of each is preferably set to about 20% by weight or less. . In the process of the present invention, each component is generally suitable for treating saturated halogenated hydrocarbons containing unsaturated impurities in a content of up to about 20% by weight. Normally, the concentration of unsaturated impurities is 1 per component
It is contained in an amount of about 0 ppm to 20% by weight. In many cases, this method has been found to be effective in reducing the concentration of unsaturated impurities to below 10 ppm.

The ozone used is not particularly limited in terms of concentration, such as direct blowing of ozone generated by an ozone generator. Normally, oxygen produced by liquid air fractionation is used as a raw material for ozone. Although the presence or absence of oxygen is not particularly limited, the concentration of ozone in the ozone-containing gas or the liquid containing ozone is 1 ppm to 100%. Care must be taken when purifying saturated halogenated hydrocarbons having an explosion range in an oxygen atmosphere. Coexistence of an inert gas such as helium, argon, or nitrogen is effective for avoiding this explosion range.

The molar ratio of the unsaturated impurities in the saturated halogenated hydrocarbon to be purified and ozone during the reaction is not particularly limited. Ozone may be supplied in an amount equal to or more than the equivalent amount of unsaturated impurities in the saturated halogenated hydrocarbon to be purified, and when the supply amount is large, a substantial amount of the saturated halogenated hydrocarbon to be purified may be lost. Industrially, unsaturated impurities 1
Ozone is 1 to 1,000,000 mol, preferably 1 to 100,000 mol, and more preferably 10 to 10,000 mol.

As the reaction type, a batch reaction, a flow-type reaction or the like can be adopted. With an ozone-containing gas containing unreacted ozone,
In order to suppress the accompanying loss of saturated halogenated hydrocarbons, it is desirable to install a cooler on the gas extraction side. Industrially, a method such as an extraction column system in which an ozone-containing gas is blown from the lower portion while saturated halogenated hydrocarbons are supplied from the upper portion and withdrawn from the lower portion can be adopted.

The reaction temperature is not particularly limited, but in order to obtain an industrially feasible reaction rate, the saturated halogenated hydrocarbon to be purified is in a range of from a temperature at which it substantially exists as a liquid to 100 ° C. is there. In addition, since the rate of addition of ozone to unsaturated impurities is high and the amount of heat generated is large, it is necessary to provide a device capable of cooling so that the reaction does not run away. On the other hand, a reaction at −50 ° C. or lower where highly reactive ozonide is accumulated in the reaction system without being decomposed should be avoided.

The reaction time varies depending on the concentration of the saturated halogenated hydrocarbon to be purified and the unsaturated impurities contained therein, the ozone blowing method and its concentration, and the reaction temperature, but in the case of a batch reaction, it is usually 1 minute to 6000 minutes. Is.

During the purification reaction, in addition to the saturated halogenated hydrocarbon containing unsaturated impurities, a solvent inert to saturated halogenated hydrocarbon and ozone may coexist. Usually, the saturated halogenated hydrocarbon to be purified is regarded as a solvent, and other solvents which require further separation are not added unless particularly required.

The reaction pressure is not particularly limited as long as the saturated halogenated hydrocarbon and / or the solvent to be purified are partially liquefied in the reaction system. The unsaturated impurities in the saturated halogenated hydrocarbon are oxidized into ozonide by the reaction with ozone. Furthermore, ozonide can be converted into stable compounds such as ketones, aldehydes and carboxylic acids by treatments such as reductive decomposition and oxidative decomposition.

[0023]

【Example】

Example 1 A 100 ml glass autoclave was equipped with a Liebig cooling tube with brine at -25 ° C and an ozone-containing gas blowing tube equipped with a ball filter for improving gas dispersion in the liquid phase. 2,2, -dichloro-1, containing unsaturated impurities shown in Table 1, was added to this autoclave.
After 50 ml of 1,1-trifluoroethane (R-123) was charged, ozone-containing oxygen having an effective ozone concentration of 2% was blown into the reactor at 30 ml / min. Reaction temperature is 10
The reaction was continued for 5 hours while maintaining the temperature at ℃ and stirring the inside of the reaction system with a PTFE stirrer to improve gas dispersion. After stopping the blowing of the ozone-containing gas, the crude liquid was collected and analyzed by FID gas chromatography. Table 1 shows the amounts of unsaturated impurities before and after the reaction. After the recovery, the amount of R-123 was about 4.7% by weight. In addition, Tables 1 to 3
“N.d.” indicates that it is not detected in FID gas chromatography.

[0024]

[Table 1]

Example 2 The reaction was performed in the same manner as in Example 1 except that 1,1,1,2-tetrafluoroethane (R-134a) was used instead of R-123 and the reaction temperature was -30 ° C. went. R-134a
The crude reaction liquid was collected by the trap-to-trap method and analyzed using FID gas chromatography.
Table 2 shows the amounts of unsaturated impurities before and after the reaction. After collection
The amount of R-134a was about 6.1% by weight.

[0026]

[Table 2]

Example 3 The reaction was performed in the same manner as in Example 1 except that 3,3-dichloro-1,1,1,2,2-pentafluoropropane (R-225ca) was used instead of R-123. went. Collect the reaction crude liquid and
It was analyzed using ID gas chromatography. Table 3 shows the amounts of unsaturated impurities before and after the reaction. After collection, R-2
The amount of 25ca was about 3.8% by weight.

[0028]

[Table 3]

Example 4 Instead of R-123, 3,3-dichloro-1,1,1,2,2-pentafluoropropane (R-225ca) and 2,2-dichloro-
1,1,1,3,3-Pentafluoropropane (R-225a
The reaction was performed in the same manner as in Example 1 except that the mixture of a) was used. The reaction crude liquid was collected and analyzed using FID gas chromatography. Table 4 shows the amounts of unsaturated impurities before and after the reaction. The amount of R-225ca and R-225aa was about 7.5% by weight.

[0030]

[Table 4]

[0031]

According to the method of the present invention, unsaturated impurities in the saturated halogenated hydrocarbon can be efficiently reduced, and the loss of the saturated halogenated hydrocarbon to be purified can be suppressed.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shin Tatematsu             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. Central Research Laboratory (72) Inventor Toshihiro Tanuma             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. Central Research Laboratory

Claims (5)

[Claims] 1. A method for purifying a saturated halogenated hydrocarbon, which comprises contacting a saturated halogenated hydrocarbon containing an unsaturated impurity with ozone to obtain a saturated halogenated hydrocarbon having a reduced content of the impurities. . 2. The method according to claim 1, wherein the saturated halogenated hydrocarbon is a hydrocarbon having at least one hydrogen and at least one fluorine. 3. The purification method according to claim 1, wherein the content of unsaturated impurities in the saturated halogenated hydrocarbon before purification is 10 ppm to 50% by weight. 4. The purification method according to claim 1, wherein the supply ratio of ozone to unsaturated impurities in the saturated halogenated hydrocarbon is 1 to 1,000,000 mol of ozone to 1 mol of unsaturated impurities. 5. The purification method according to claim 1, wherein the reaction temperature is in the range from the temperature at which the saturated halogenated hydrocarbon is substantially present as a liquid to 100 ° C.