JPH10310541A - Method for separating 1,1,1,3,3-pentafluoropropane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain the subject compound by distilling a mixture of liquids difficult to separate or liquefiable gases in the presence of a specific solvent. SOLUTION: The objective compound useful for foaming agents for hard urethane foams or refrigerants is easily obtained by distilling a mixture difficult to separate containing 1,1,1,3,3-pentaflurorpropane (abbreviated to HFC-245fa) and 1-chloro-3,3-trifluoro-trans-1-propene [abbreviated to HCFC-1233zd (t)] in the presence of at least one of the following 3 compounds, which are each a carbon chloride, a chlorinated hydrocarbon and a fluorinated chlorinated hydrocarbon and have higher melting points than HCFC-1233zd; a compound of the formula CFYCl3- YCH2 CHFWCl2- W (Y is 0-3; W is 0-2; but Y is not 3 and W is not 2 at the same time); a compound of the formula CFMCl3- MCHCFNCl2- N (M is 0-3, N is 0-2; but Y is not 3 and N is not 2 at the same time) and a compound of the formula CHFp Cl1-p CHCFQCL3- Q (P is 0 or 1; Q is 0-2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for purifying 1,1,1,3,3-pentafluoropropane (hereinafter referred to as HFC-245fa) useful as a foaming agent for rigid urethane foam or a refrigerant. Specifically, 1-chloro-
The present invention relates to a purification method for separating HFC-245fa from crude 1,1,1,3,3-pentafluoropropane with 3,3,3-trifluoro-trans-1-propene or the like.

[0002]

2. Description of the Related Art 1,1-Dichloro-1-fluoroethane, which is currently used as a foaming agent for rigid urethane foam, has a low but ozone-depleting ability, and is a subject to be regulated in the future as a transient substitute. Has become. Therefore, HFC-245fa, which does not have ozone depleting ability,
-Dichloro-1-fluoroethane is attracting attention as one of alternative substances.

[0003] The production method of HFC-245fa is 1,1,1.
US Pat. No. 5,839,045 discloses a method of liquid-phase fluorination of 1,3,3-pentachloropropane with hydrogen fluoride using antimony pentachloride as a catalyst
P5,574,192, the intermediate formed 1-chloro- when the reaction is carried out continuously.
3,3,3-trifluoro-1-propene (hereinafter, HC
FC-1233zd. When the trans form and the cis form are to be distinguished from each other,
(T), referred to as HCFC-1233zd (c). ) Is H
Since FC-245fa has a boiling point close to that of FC-245fa, it is extracted with a trace amount in the product. Similarly, when 1,1,1,3,3-pentachloropropane or HCFC-1233zd is vapor-phase fluorinated with hydrogen fluoride using a chromium catalyst or the like, a considerable amount of HCFC-1 cannot be ignored due to an equilibrium reaction.
233zd may be included in the product.

[0004] Distillation is generally employed as a method for separating a liquid or liquefiable gas mixture, but it is extremely difficult to separate a mixture having a similar boiling point by distillation. HF
C-245fa and HCFC-1233zd (t)
Are close to 15.3 ° C. and 21.0 ° C., respectively, and HCFC-1233z
Since d (t) distills out before HFC-245fa, it is inferred that the relative volatility of both is close to 1. It has been reported that the extractive distillation method is effective for separating such a mixture. For example, in the separation of pentafluoroethane and chloropentafluoroethane, 1,2-dichlorotetrafluoroethane is used as an extractant in extractive distillation. Good results have been obtained (US Pat. No. 5,087,32).
9). Further, ketones such as acetone and n-pentane, and paraffins are used as extractants in the same extractive distillation of pentafluoroethane and chloropentafluoroethane (JP-A-7-133240). Further, in the extractive distillation of pentafluoroethane and 1,1,1-trifluoroethane, carbon chlorides or hydrocarbons having 1 to 2 carbon atoms are used as an extractant (Japanese Patent Laid-Open No. 9-1248).
7).

[0005]

SUMMARY OF THE INVENTION HFC-245fa
However, as described above, there is a problem that even if an attempt is made to separate from HCFC-1233zd (t) by an ordinary distillation method, the components are not easily separated into respective components.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present inventors attempted to establish a method for producing HFC-245fa suitable for production on an industrial scale.
After intensive studies on a method for promoting the separation of FC-245fa from HCFC-1233zd (t), it was found that HCF-245fa can be separated extremely easily by distillation in the presence of a specific solvent, and the present invention. Is reached.

That is, the present invention relates to 1,1,1,3,3
-Pentafluoropropane and 1-chloro-3,3,3-
A method for distilling a mixture comprising trifluoro-trans-1-propene to separate 1,1,1,3,3-pentafluoropropane, wherein 1 1,1,1,3,3-comprising the presence of carbon chloride, chlorohydrocarbon or fluorinated chlorohydrocarbon having a higher boiling point than -chloro-3,3,3-trifluoro-trans-1-propene 1-chloro-3,3,3-trifluoro-t of pentafluoropropane
ran-1-propene.

[0008] HFC-245f to which the method of the present invention is applied
The composition of the mixture comprising a and HCFC-1233zd (t) generally depends on the reaction conditions when producing HCF-245fa. The product composition of the reaction depends on parameters such as the reaction temperature, pressure and the concentration of hydrogen chloride in the reaction system for chemical equilibrium, and has a specific composition.In general, the production efficiency is maximized or the production cost is minimized. Is set to In the method of the present invention, the composition of this mixture is not particularly limited, but HFC-245fa and HCFC-
The molar ratio of 1233zd is generally 0.01 to 1 mol of HCFC-1233zd (t) with respect to 1 mol of HFC-245fa. HCFC-1233zd
If (t) exceeds 1 mol, there is no technical problem, but HCFC-1233zd (t) to be circulated increases, which is not economically preferable.

HFC-245f to which the method of the present invention is applied
The method for producing a mixture comprising a and HCFC-1233zd (a mixture of a trans form and a cis form) is not particularly limited. For example, the general formula CF _Y Cl _3-Y CH ₂ CHF _W Cl
A method of fluorinating propanes represented by _2-W (wherein W represents 0 or 1 and Y represents an integer of 0 to 3) with hydrogen fluoride in a liquid phase in the presence of a catalyst, 1,1,
A method for producing HFC-245fa by liquid-phase fluorination of 3,3-pentachloropropane with hydrogen fluoride, wherein an antimony compound is used as a catalyst, or 1,1,1,3,3-pentachloropropane or HCFC-1233zd produced by a method of fluorinating with hydrogen fluoride in the gas phase in the presence of a chromium catalyst can be mentioned.

In these methods, in addition to hydrogen chloride and HFC-245fa, a general formula of CF _Y Cl _3-Y CH ₂ CHF _W Cl _2-W (where Y is an integer of 0 to 3) , W is an integer of 0 to 2, and Y is not 3, and W is not 2 at the same time.) Or a general formula: CF _M Cl _3-M CHCF _N Cl _2-N (wherein, M is an integer of 0 to 3, and N is 0 or 1.)
Or general _{formula, CHF P Cl 1-P CHCF} Q Cl 3-Q ( wherein, P is an integer of 0 or 1, Q is 0-3.)
And unreacted hydrogen fluoride are obtained as a reaction product, but often accompanied by HCFC-1233zd. HCFC- usually produced under such conditions
Although the molar ratio of 1233zd (t) / HCFC-1233 (c) is 5 to 10/1, the present invention can be applied regardless of this molar ratio. It is desirable to apply the method of the present invention after removing hydrogen chloride and hydrogen fluoride, which are acidic components, by washing with water or a basic solution or by cooling and coagulation.

The object to be treated (raw material) to which the present invention is applied may be the reaction product as described above, but is substantially HFC-234fa and HCFC-1233 (t) by distillation or the like.
In some cases, it may be preliminarily purified from HCFC-1233 (c).

The solvent as the third component used in the method of the present invention, which is used as an extractant, is a substance that can change the relative volatility of HCFC-1233zd (t) with respect to HFC-245fa, It is preferable to have a sufficiently high boiling point that can easily separate from the polymer. Further, HF is mixed so as not to affect the reaction even if mixed in the reaction system.
It is desirably a raw material or an intermediate product used in the production of C-245fa. In the case of industrial use, it is desirable to be nonflammable, and examples of solvents suitable for such conditions include carbon chloride-based, chlorinated hydrocarbon-based and fluorinated chlorohydrocarbon-based solvents.

The raw materials or intermediate products used in the production of HFC-245fa include the general formula: CF _Y Cl _3-Y CH ₂ CHF _W Cl _2-W (where Y is an integer of 0-3, and W is A compound represented by the following general formula: CF _M Cl _3-M CHCF _N Cl _2-N (where M is 0) And N is an integer of 0 to 2 and at the same time, M is not 3, and N is not 2.) or a general formula: CHF _P Cl _1-P CHCF _Q Cl _3-Q (where P is 0 or 1, and Q is an integer of 0 to 2.)
The compound represented by is suitable. Specifically, 1,1,1,3,3-pentachloropropane, 1,3,3,3-tetrachloropropene or 1,1,3,3-tetrachloropropene is preferred as the chlorinated hydrocarbon solvent. ,
In addition, 1-fluoro-
1,1,3,3-tetrachloropropane, 1,1-difluoro-1,3,3-trichloropropane, 1,3-difluoro-1,1,3-trichloropropane, 1,1,
1-trifluoro-3,3-dichloropropane, 1,
1,3-trifluoro-1,3-dichloropropane or 1,1,1,3-tetrafluoro-3-chloropropane is preferred. These compounds are all 1,1,
1,3,3-pentachloropropane, 1,1,1,3-
It is a compound produced or derived as an intermediate in the process of producing HFC-245fa from tetrachloropropene or 1,1,3,3-tetrachloropropene and can be preferably used. The solvent may be used alone or as a mixture of two or more. Moreover, HFC-245fa and HCFC-
It is also possible to use a mixture excluding 1233zd (t) and compounds having a lower boiling point, or a mixture excluding some high-boiling components therefrom.

[0014] Further, as a solvent which is another preferable third component, ethane having 3 to 5 chlorine atoms, ethylene having 3 to 4 chlorine atoms, or methane having 2 to 3 chlorine atoms is used. Is preferred. Specifically, trichloroethylene, tetrachloroethylene, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane,
Examples thereof include 1,1,1,2-tetrachloroethane, pentachloroethane, dichloromethane and chloroform.

Further, the above-mentioned solvent composed of carbon chloride, chlorinated hydrocarbon and fluorinated chlorohydrocarbon used as the third component can be used as a mixture.

The process of the present invention can be carried out by using an ordinary distillation column. However, it is preferable to use a packed column or a plate column. HCF-245fa was distilled off from the top of the column, and the extractant and HCFC-1233zd were added to the distillation can.
(T) is recovered and subjected to extractive distillation. The operating conditions such as the temperature at each part of the distillation column, the supply stage of the raw material, and the supply amount of the extractant are not particularly limited. However, the performance of the distillation column, HCF-245fa and HCFC-1233 in the non-treated product (raw material) are not limited.
Although it differs depending on the content ratio with zd (t), the type and amount of the extractant used, and the like, they can be determined by preliminary tests. In order to maintain the stability of the distillation operation, an extractant may be added to the distillation raw material. The method of the present invention can be performed in a discontinuous or continuous operation,
Industrially, continuous operation is preferred.

A mixture of a part of the extracted raw material and an extractant can be used as it is as a reaction raw material when the extractant can be a raw material used for producing HFC-245fa or an intermediate product. Further, the extractant is separated by an operation such as stripping, and a part of the raw material is returned to the reaction system again, while the extractant can be recycled and reused.

In the method of the present invention, the amount of the extractant is not particularly limited, and the higher the ratio of the extractant to the raw material (the higher the extractant concentration), the more efficient the separation in the extraction, but the ratio is too high. In such a case, it is not economically preferable in terms of an increase in the size of the apparatus and an increase in the cost of utilities. Conversely, if the ratio is too low, the separation effect is small and the product purity cannot be increased, which is not preferable. Therefore, for example, 50 to 2,000 parts by weight of the extractant per 100 parts by weight of the raw material,
~ 1000 parts by weight are preferred.

An apparatus for performing the method of the present invention comprises glass,
Stainless steel or tetrafluoroethylene resin, chlorotrifluoroethylene resin, vinylidene fluoride resin, PFA
Those made of carbon steel lined with resin or the like can be suitably used.

[0020]

The present invention will be described below in detail with reference to examples. In Examples, "%" represents "% by weight".

Example 1 A glass rectification column having a theoretical diameter of 12 and packed with a stainless steel heli-pack (filler manufactured by Tokyo Special Wire Mesh Co., Ltd.) having a tower diameter of 13 mmφ was used.
43.8% of C-1233zd (t), HCFC-12
A raw material containing 5.1% of 33zd (c) and 51.1% of HFC-245fa was taken from a position 10 stages from the top of the column to 31.d.
At 0 g / hr, 1,1,1,3,3-pentachloropropane was supplied at 98.3 g / hr from the four stages from the top of the tower. Under normal pressure, reflux ratio 4, bottom temperature 50
Distillation was carried out at 1 ° C., and distillation was performed at 12.6 g / hr from the top of the column. The yield of the bottom liquid was 115.2 g / hr.
Table 1 shows the compositions of the raw material, the distillate and the bottom liquid.

[0022]

[Table 1]

Example 2 A glass rectification column having a theoretical diameter of 12 and packed with a stainless steel heli-pack and having a tower diameter of 13 mmφ was used, and HCFC-1233zd (t) was added to a column of 10.4.
%, HCFC-1233zd (c) 0.2% and H
The raw material containing 89.4% of FC-245fa is 10
30.9 g / hr from the step part, and 1,1,1,
3,3-Pentachloropropane was supplied at a rate of 100.5 g / hr from four stages from the top of the tower. Distillation was performed under normal pressure at a reflux ratio of 2 and a bottom temperature of 60 ° C.
Distilled at 3.0 g / hr. The amount of bottom liquid generated is 10
It was 5.5 g / hr. Table 2 shows the compositions of the raw material, the distillate and the bottom liquid.

[0024]

[Table 2]

Example 3 Using a glass rectification column having a theoretical column number of 12 and packed with a stainless steel helipak having a column diameter of 13 mmφ, HCFC-1233zd (t) was adjusted to 10.4.
% Of a raw material containing 0.2% of HCFC-1233zd (c) and 89.4% of HFC-245fa from the top of the column.
It is 18.1 g / hr from the 0th stage, and 1,1,1-
Trifluoro-3,3-dichloropropane was added from the top 4
It was supplied at 72.4 g / hr from the column site. Distillation was performed under normal pressure at a reflux ratio of 4 and a bottom temperature of 60 ° C., and was distilled from the top of the column at 10.0 g / hr. The yield of the bottom liquid was 78.4 g / hr. Table 3 shows the compositions of the raw material, the distillate and the bottom liquid.

[0026]

[Table 3]

Example 4 Using a glass rectification column having a theoretical column number of 12 and packed with a stainless steel helipak having a column diameter of 13 mmφ, HCFC-1233zd (t) was 43.8.
% Of a raw material containing 5.1% of HCFC-1233zd (c) and 51.1% of HFC-245fa from the top of the column.
35.1 g / hr was supplied from the zero-stage portion, and chloroform was supplied at 118.7 g / hr from the four-stage portion from the top of the tower. Distillation was carried out under normal pressure at a reflux ratio of 4 and a bottom temperature of 50 ° C., and was distilled at 15.9 g / hr from the top of the column. The yield of the bottom liquid was 133.8 g / hr. material,
Table 4 shows the compositions of the distillate and the bottom liquid.

[0028]

[Table 4]

[Example 5] HCFC-1233zd (t) was 46.0 using a glass rectification column having a theoretical column number of 12 and packed with a stainless steel heli-pack and having a column diameter of 13 mmφ.
% Of a raw material containing 5.6% of HCFC-1233zd (c) and 48.4% of HFC-245fa from the top of the column.
Trichlorethylene was fed at 44.3 g / hr from the zero-stage portion and at 114.3 g / hr from the four-stage portion from the top. Under normal pressure, reflux ratio 4, bottom temperature 60
C. and distilled at 14.3 g / hr from the top of the column. The yield of the bottom liquid was 138.7 g / hr.
Table 5 shows the compositions of the raw material, the distillate and the bottom liquid.

[0030]

[Table 5]

Example 6 Using a glass rectification column having a theoretical column number of 12 and packed with a stainless steel helipak having a column diameter of 13 mmφ, HCFC-1233zd (t) was adjusted to 10.4.
% Of a raw material containing 0.2% of HCFC-1233zd (c) and 89.4% of HFC-245fa from the top of the column.
Trichlorethylene was supplied at 40.0 g / hr from the zero-stage part and 120.0 g / hr from the four-stage part from the top. Under normal pressure, reflux ratio 4, bottom temperature 60
Distillation was carried out at a temperature of 0 ° C., and distillation was performed at a rate of 30.8 g / hr from the top of the column. The yield of the bottom liquid was 128.2 g / hr.
Table 6 shows the compositions of the raw material, the distillate and the bottom liquid.

[0032]

[Table 6]

[Example 7] HCFC-1233zd (t) was 43.8 using a glass rectification column having a theoretical diameter of 12 and packed with a stainless steel helipak having a tower diameter of 13 mmφ.
% Of a raw material containing 5.1% of HCFC-1233zd (c) and 51.1% of HFC-245fa from the top of the column.
31.5 g / hr from the 0th stage, and 170.9 g / hr from the 4th stage from the top.
Respectively. Under normal pressure, reflux ratio 4, bottom temperature 6
Distillation was performed at 0 ° C., and distillation was performed at 13.6 g / hr from the top of the column. The production amount of the bottom liquid was 186.4 g / hr. Table 7 shows the compositions of the raw material, the distillate and the bottom liquid.

[0034]

[Table 7]

[Comparative Example] A glass rectification tower having a theoretical diameter of 12 and packed with a stainless steel helipak having a tower diameter of 13φ was used. HCFC-1233zd (t) was 44.3% and HC was used.
8.1% of FC-1233zd (c) and HFC-
A raw material containing 47.6% of 245fa was supplied at a rate of 31.0 g / hr from a site at 10 stages from the top of the tower. Distillation was performed under normal pressure at a reflux ratio of 4 and a bottom temperature of 20 ° C., and 29.6 from the top of the column.
Distilled at g / hr. Table 8 shows the composition of the distillate.

[0036]

[Table 8]

[0037]

According to the method of the present invention, 1, 1 which is difficult to separate is used.
1,1,3,3-pentafluoropropane and 1-chloro-3,3,3-trifluoro-trans-1-propene are extracted with carbon chlorides, chlorohydrocarbons or fluorinated chlorohydrocarbons The effect of the present invention is that it can be easily separated by extractive distillation.

Claims (7)

[Claims] 1. The method of claim 1, wherein 1,1,1,3,3-pentafluoropropane and 1-chloro-3,3,3-trifluoro-tr
1,1, from a mixture comprising ans-1-propene
A method for separating 1,3,3-pentafluoropropane by distillation, wherein 1-chloro-3,3,3-trifluoro-tran is used as a third component when the mixture is distilled.
1- of 1,1,1,3,3-pentafluoropropane, which comprises the presence of carbon chloride, chlorohydrocarbon or fluorinated chlorohydrocarbon having a higher boiling point than s-1-propene
Chloro-3,3,3-trifluoro-trans-1-
How to separate from propene. 2. A method according to claim 1, wherein the third component is a general formula: CF _Y Cl _3-Y CH ₂ CHF _W Cl _2-W (where Y is an integer of 0-3, W is an integer of 0-2, and A compound represented by the general formula: CF _M Cl _3-M CHCF _N Cl _2-N (wherein M is an integer of 0-3, and N is 0-2) Wherein M = 3 and N = 2 are not at the same time) or a general formula: CHF _P Cl _1-P CHCF _Q Cl _3-Q (where P is 0 or 1, Q is 0 to 2) It is an integer.)
The separation method according to claim 1, which is a compound represented by the formula: 3. A chloride wherein the third component is selected from 1,1,1,3,3-pentachloropropane, 1,3,3,3-tetrachloropropene or 1,1,3,3-tetrachloropropene. The method according to claim 1, wherein the separation method is a hydrocarbon. 4. The method according to claim 1, wherein the third component is 1,1,1-trifluoro-.
The separation method according to claim 1, wherein the separation method is a fluorinated hydrocarbon selected from 3,3-dichloropropane and 1,1,1,3-tetrafluoro-3-chloropropane. 5. The separation according to claim 1, wherein the third component is ethane having 3 to 5 chlorine atoms, ethylene having 3 to 4 chlorine atoms, or methane having 2 to 3 chlorine atoms. Method. 6. The method according to claim 1, wherein the third component is trichloroethylene, tetrachloroethylene, 1,1,2-trichloroethane,
The separation method according to claim 1, wherein the separation method is 1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, pentachloroethane, dichloromethane or chloroform. 7. 1,1,1,3,3-pentafluoropropane and 1-chloro-3,3,3-trifluoro-tr
a mixture consisting of ans-1-propene,
1,1,1,3,3-pentafluoropropane and 1-chloro, characterized by extractive distillation using at least one compound selected from chlorinated hydrocarbons or fluorinated chlorohydrocarbons as an extractant A method for separating 3,3,3-trifluoro-trans-1-propene.