Method for separating 1, 1, 1, 3, 3-pentafluoropropane from trans-1-chloro-3, 3, 3-trifluoropropene

Abstract

The invention provides a method for separating 1, 1, 1, 3, 3-pentafluoropropane and trans-1-chloro-3, 3, 3-trifluoropropene, which is characterized in that the 1, 1, 1, 3, 3-pentafluoropropane and the trans-1-chloro-3, 3, 3-trifluoropropene are separated from a mixture of the 1, 1, 1, 3, 3-pentafluoropropane and the trans-1-chloro-3, 3, 3-trifluoropropene through extractive distillation, and the 1, 1, 1, 3, 3-pentafluoropropane and the trans-1-chloro-3, 3, 3-trifluoropropene are separated from the mixture of the 1, 1, 1, 3, 3-pentafluoropropane and the trans-1-chloro-3, 3, 3-trifluoropropene. An extracting agent used in extractive distillation is one or a combination of more than one of ester compounds, ether compounds and organic amine compounds. By utilizing the characteristic that the relative volatility of 1, 1, 1, 3, 3-pentafluoropropane and trans-1-chloro-3, 3, 3-trifluoropropene can be obviously changed by adding the selected extracting agent, the 1, 1, 1, 3, 3-pentafluoropropane and trans-1-chloro-3, 3, 3-trifluoropropene can be efficiently and simultaneously separated by adopting two devices, namely an extractive distillation tower and an extracting agent recovery tower, and the relative volatility of 1, 1, 1, 3, 3-pentafluoropropane and trans-1-chloro-3, 3, 3-trifluoropropene can be effectively and simultaneously separated by adopting the two devices, namely the 1, 1, 1, 3, 3-pentafluoropropane and trans-1-chloro-3, 3, 3-trifluoropropene as well as the 1, 1, 1, 3, 3-trifluoropropene. The purity of the 1, 1, 1, 3, 3-pentafluoropropane and the purity of the trans-1-chloro-3, 3, 3-trifluoropropene are both greater than 99.5 wt%.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, relates to polyfluoroolefins, and specifically relates to a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. Background Art

[0002] Trans-1-chloro-3,3,3-trifluoropropene (E-HCFO-1233zd) has an ozone depletion value (ODP) of 0.00024 and a global warming potential (GWP) of 4.7 to 7.0. It is recognized by the international community as an ideal low-carbon and environmentally friendly substitute for high-GWP hydrofluorocarbons, such as being used as a blowing agent to replace 1,1,1-dichlorofluoroethane (HCFC-141b) and 1,1,3,3,3-pentafluoropropane (HFC-245fa), and as a cleaning agent to replace methyl chloroform.

[0003] HFC-245fa is widely used as a third-generation blowing agent and is also a raw material for synthesizing trans-1,3,3,3-tetrafluoropropylene (E-HFO-1234ze). E-HFO-1234ze has an ozone depletion potential of zero and a greenhouse effect potential of 6. It has excellent environmental performance and is considered to be an ideal substitute for 1,1,1,2-tetrafluoroethane (HFC-134a).

[0004] The common industrial method for preparing E-HCFO-1233zd and HFC-245fa is to use 1,1,1,3,3-pentachloropropane as the raw material and obtain it through gas phase or liquid phase fluorination reaction. The reaction product is subjected to steps such as distillation and acid removal to obtain crude E-HCFO-1233zd or HFC-245fa, but both crude products contain E-HCFO-1233zd and HFC-245fa, and the boiling points of E-HCFO-1233zd (boiling point is 18.3°C) and HFC-245fa (boiling point is 15°C) are close, and conventional distillation technology is difficult to separate the two.

[0005] Chinese invention patent application publication number CN1320109A reports a method for reducing the content of E-HCFO-1233zd by chlorine chlorination at high temperature (400°C) in the presence of an activated carbon catalyst. This method chemically converts E-HCFO-1233zd into a chloride with a higher boiling point. Although the problem of difficulty in separating E-HCFO-1233zd from HFC-245fa is solved, part of HFC-245fa is also chlorinated. Therefore, this method converts a certain amount of E-HCFO-1233zd and HFC-245fa into high-grade waste, which is unacceptable in industry. In addition, the use of chlorine at high temperature increases the danger to equipment, operators and the environment.

[0006] The U.S. invention patent with application publication number US6120652 reports a method for removing E-HCFO-1233zd by extractive distillation to purify HFC-245fa. The method uses perchlorocarbons, hydrochlorocarbons or fluorochlorocarbons as extractants, but perchlorocarbons, hydrochlorocarbons or fluorochlorocarbons all contain chlorine atoms and have an ODP value of not 0, which will destroy the atmospheric ozone layer and are substances that are banned or restricted for use under the Montreal Protocol on the Depletion of the Ozone Layer.

[0007] The Chinese patent application with the publication number CN106631683A provides a method for purifying HFC-245fa. The method uses ethers, alcohols, nitriles, ketones, amides or sulfoxide compounds as extractants, removes olefin E-HCFO-1233zd by extractive distillation, and purifies HFC-245fa (98-99.5wt%) from crude products (99.8-99.9wt%). The method only purifies and separates HFC-245fa, but does not purify E-HCFO-1233zd at the same time, and the range of crude HFC-245fa raw materials is relatively narrow (98-99.5wt%). Summary of the invention

[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene, so as to solve the technical problem that the amount of extractant used in the separation method in the prior art needs to be further reduced.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0010] A method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene, wherein the method separates 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene from a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene by extractive distillation, wherein the extractant used in the extractive distillation is one or a combination of more than one of an ester compound, an ether compound and an organic amine compound.

[0011] The present invention also has the following technical features:

[0012] Preferably, the ester compound is an ester compound containing 9 to 13 carbon atoms.

[0013] More preferably, the extractant is an ester compound containing 9 to 13 carbon atoms, such as octyl formate, isooctyl acetate, isopentyl valerate, isopropyl hexanoate or ethyl undecanoate.

[0014] Preferably, the ether compound is a benzyl-containing ether compound.

[0015] More preferably, the benzyl-containing ether compound is benzyl methyl ether, benzyl propyl ether, benzyl butyl ether or benzyl isobutyl ether.

[0016] Preferably, the organic amine compound is an organic amine compound containing 8 carbon atoms.

[0017] More preferably, the organic amine compound containing 8 carbon atoms is N-methylheptylamine, N-ethylhexylamine, N-propylpentylamine or di-n-butylamine.

[0018] Further preferably, the extractant is one or a combination of more than one of benzyl methyl ether, ethyl undecanoate and di-n-butylamine.

[0019] Specifically, the method comprises the following steps:

[0020] Step 1, using a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene as a raw material, wherein the mass percentage of 1,1,1,3,3-pentafluoropropane in the raw material is 6% to 10%; adding the raw material and the extractant into an extractive distillation tower (T1), wherein the mass ratio of the extractant to the raw material is (18 to 22):1, the top fraction of the extractive distillation tower (T1) is a 1,1,1,3,3-pentafluoropropane product, and the bottom fraction of the extractive distillation tower (T1) is trans-1-chloro-3,3,3-trifluoropropene and the extractant, and the operating conditions of the extractive distillation tower (T1) are: an operating pressure in the tower of 170 to 190 kPa, a top temperature of 28.9 to 31.9° C., a bottom temperature of 143.3 to 148.0° C., and a reflux ratio of 0.07 to 3.0;

[0021] Step 2, the bottom fraction of the extractive distillation tower (T1) enters the extractant recovery tower (T2), the bottom fraction of the extractant recovery tower (T2) is the extractant, which is circulated to the extractive distillation tower (T1); the top fraction of the extractant recovery tower (T2) is trans-1-chloro-3,3,3-trifluoropropene; the operating conditions of the extractant recovery tower (T2) are: the operating pressure in the tower is 160-170 kPa, the top temperature is 31.0-32.9°C, the bottom temperature is 174.7-189.7°C, and the reflux ratio is 1.3-3.6.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] (I) The present invention utilizes the characteristic that the addition of the selected extractant can significantly change the relative volatility of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. By using two devices, namely an extractive distillation tower and an extractant recovery tower, 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene can be efficiently separated simultaneously. The purity of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene is greater than 99.5wt%.

[0024] (II) The extractant used in the present invention is a conventional, non-highly corrosive organic solvent, does not contain chlorine atoms, has an ODP value of 0, will not damage the ozone layer, and the separation and purification process is green and safe.

[0025] (III) In the extractant used in the present invention, there is a strong van der Waals interaction between the extractant containing a Π-Π conjugated structure and trans-1-chloro-3,3,3-trifluoropropene, which can increase the solubility of trans-1-chloro-3,3,3-trifluoropropene in the above-mentioned extractant, so that under the same conditions, the escape difficulty of trans-1-chloro-3,3,3-trifluoropropene is lower, so as to achieve the purpose of significantly improving the relative volatility of the azeotropic system of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene.

[0026] (IV) The entire separation and purification process of the present invention adopts mature distillation technology, the operation process is simple, and the amount of extractant used is small, and the energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a process flow chart for the separation of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene.

[0028] Figure 1 In the embodiment, T1 is an extractive distillation tower; T2 is an extractant recovery tower; the feed is a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene; the overhead product of the extractive distillation tower is 1,1,1,3,3-pentafluoropropane; the bottom effluent of the extractive distillation tower is an extractant containing trans-1-chloro-3,3,3-trifluoropropene; the overhead product of the extractant recovery tower is trans-1-chloro-3,3,3-trifluoropropene; and the bottom effluent of the extractant recovery tower is an extractant.

[0029] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0030] It should be noted that, unless otherwise specified, all equipment, raw materials and reagents in the present invention are those known in the prior art and can be obtained from commercial sources.

[0031] In the present invention, the extractant is an ester compound, an ether compound or an organic amine compound with a boiling point in the range of 50°C to 260°C.

[0032] The principle of extractive distillation is to change the relative volatility of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene by adding an extractant, so that the relative volatility of 1,1,1,3,3-pentafluoropropane relative to trans-1-chloro-3,3,3-trifluoropropene is greater than 1, thereby separating the two. Here, the relative volatility (α) of 1,1,1,3,3-pentafluoropropane relative to trans-1-chloro-3,3,3-trifluoropropene is defined as follows:

[0033]

[0034] To determine the relative volatility α of 1,1,1,3,3-pentafluoropropane relative to trans-1-chloro-3,3,3-trifluoropropene after the addition of the extractant. The inventors used a 300ml stainless steel reactor with gas and liquid sampling valves. 50g of extractant and 2.5g of 1,1,1,3,3-pentafluoropropane / trans-1-chloro-3,3,3-trifluoropropene mixture (wherein the content of 1,1,1,3,3-pentafluoropropane is 6wt%) were added to the reactor. The reactor was immersed in a 15°C constant temperature oil bath, and the materials were stirred magnetically to fully mix the materials. When the materials in the reactor reached gas-liquid equilibrium, gas phase samples and liquid phase samples were taken, and the composition content of each phase was determined by gas chromatography. According to the above relative volatility definition formula, the relative volatility α value of each experiment was calculated, and the relevant experimental results are shown in Table 1.

[0035] Table 1 α value after adding extractant

[0036]

[0037]

[0038] As shown in Table 1, the addition of esters, ethers or organic amines with boiling points in the range of 50°C to 260°C changes the relative volatility of 1,1,1,3,3-pentafluoropropane to trans-1-chloro-3,3,3-trifluoropropene, and α changes from close to 1 when no extractant is added to significantly greater than 1, making the relatively non-volatile 1,1,1,3,3-pentafluoropropane more volatile, that is, the 1,1,1,3,3-pentafluoropropane product can be obtained from the top of the tower by extractive distillation.

[0039] From the extractants tested in Table 1, it can be seen that the preferred extractants are benzyl methyl ether, ethyl undecanoate, and di-n-butylamine. In addition, the above extractants can be used alone or in combination of two or more.

[0040] The invention is verified by quantum chemical calculation and gas-liquid equilibrium experiment, and it is found that in the extractant, there is a strong van der Waals interaction between the extractant containing a Π-Π conjugated structure and trans-1-chloro-3,3,3-trifluoropropene, which can improve the solubility of trans-1-chloro-3,3,3-trifluoropropene in the extractant, so that under the same conditions, the escape difficulty of trans-1-chloro-3,3,3-trifluoropropene is lower, so as to achieve the purpose of significantly improving the relative volatility of the azeotropic system of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene.

[0041] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0042] Embodiment 1:

[0043] This embodiment provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method separates 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene from a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene by extractive distillation. The extractant used in the extractive distillation is di-n-butylamine:

[0044] like Figure 1 As shown, the method comprises the following steps:

[0045] Step 1, using a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene as a raw material, wherein the mass percentage of 1,1,1,3,3-pentafluoropropane in the raw material is 6%; adding the raw material and the extractant into an extractive distillation tower T1, the flow rate of the raw material is 100 g / h, the mass ratio of the extractant to the raw material is 20:1, the top fraction of the extractive distillation tower T1 is a 1,1,1,3,3-pentafluoropropane product, and the bottom fraction of the extractive distillation tower T1 is trans-1-chloro-3,3,3-trifluoropropene and the extractant. The operating conditions of the extractive distillation tower T1 are shown in Table 2.

[0046] In this embodiment, the extractive distillation tower T1 is a packed tower with a tower diameter of Φ25 mm, and is filled with Φ3*3θ ring stainless steel packing, and the height of the packing layer is 0.8 m.

[0047] Step 2: The bottom fraction of the extractive distillation tower T1 enters the extractant recovery tower T2; the bottom fraction of the extractant recovery tower T2 is the extractant, which is circulated to the extractive distillation tower T1; the top fraction of the extractant recovery tower T2 is trans-1-chloro-3,3,3-trifluoropropene; the operating conditions of the extractant recovery tower T2 are shown in Table 2.

[0048] Table 2 Tower operating conditions in Example 1

[0049] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 180 Operating pressure / kPa(A) 170 Tower top temperature / ℃ 30.6 Tower top temperature / ℃ 32.9 Tower temperature / ℃ 144.0 Tower temperature / ℃ 178.5 Reflux ratio 0.07 Reflux ratio 3.0

[0050] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.6 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.5 wt %.

[0051] Embodiment 2:

[0052] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 1, except that:

[0053] In this embodiment, the extractant used in the extractive distillation is benzyl methyl ether:

[0054] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 3.

[0055] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 3.

[0056] Table 3 Tower operating conditions in Example 2

[0057] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 180 Operating pressure / kPa(A) 170 Tower top temperature / ℃ 30.6 Tower top temperature / ℃ 32.9 Tower temperature / ℃ 143.3 Tower temperature / ℃ 189.7 Reflux ratio 3.0 Reflux ratio 2.0

[0058] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.6 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.8 wt %.

[0059] Embodiment 3:

[0060] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 1, except that:

[0061] In this embodiment, the extractant used in the extractive distillation is ethyl undecanoate:

[0062] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 4.

[0063] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 4.

[0064] Table 4 Tower operating conditions in Example 3

[0065]

[0066]

[0067] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.6 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.5 wt %.

[0068] Embodiment 4:

[0069] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 2, except that:

[0070] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 5.

[0071] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 5.

[0072] Table 5 Tower operating conditions in Example 4

[0073] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 170 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 28.9 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 148.0 Tower temperature / ℃ 174.7 Reflux ratio 0.12 Reflux ratio 3.6

[0074] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.5 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.5 wt %.

[0075] Embodiment 5:

[0076] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 4, except that:

[0077] In this embodiment, the extractant used in the extractive distillation is a mixture of di-n-butylamine and benzyl methyl ether in a mass ratio of 1:1.

[0078] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 6.

[0079] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 6.

[0080] Table 6 Tower operating conditions in Example 5

[0081] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 170 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 28.9 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 143.5 Tower temperature / ℃ 188.2 Reflux ratio 0.85 Reflux ratio 2.2

[0082] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.6 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.8 wt %.

[0083] Embodiment 6:

[0084] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 4, except that:

[0085] In this embodiment, the extractant used in the extractive distillation is a mixture of benzyl methyl ether and ethyl undecanoate in a mass ratio of 1:1.

[0086] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 7.

[0087] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 7.

[0088] Table 7 Tower operating conditions in Example 6

[0089] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 31.9 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 143.6 Tower temperature / ℃ 189.4 Reflux ratio 1.78 Reflux ratio 2.8

[0090] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.6 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.7 wt %.

[0091] Embodiment 7:

[0092] This example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 4, except that:

[0093] In this embodiment, the extractant used in the extractive distillation is a mixture of di-n-butylamine, benzyl methyl ether and ethyl undecanoate in a mass ratio of 1:1:1.

[0094] In this embodiment, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 8.

[0095] In this embodiment, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 8.

[0096] Table 8 Tower operating conditions in Example 7

[0097] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 31.9 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 143.6 Tower temperature / ℃ 189.0 Reflux ratio 1.5 Reflux ratio 1.3

[0098] In this embodiment, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.8 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.9 wt %.

[0099] Comparative Example 1:

[0100] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 1, except that:

[0101] In this comparative example, the extractant used in the extractive distillation is N-methylpyrrolidone.

[0102] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 9.

[0103] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 9.

[0104] Table 9 Tower operating conditions in comparative example 1

[0105] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 32.0 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 198.2 Tower temperature / ℃ 204.7 Reflux ratio 4.0 Reflux ratio 9.3

[0106] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.4 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.3 wt %.

[0107] Compared with Comparative Example 1, under the same feeding conditions, in Example 1, the purity of HFC-245fa is 99.6wt%, which is higher than the purity of HFC-245fa of Comparative Example 1 (99.4wt%); the purity of E-HCFO-1233zd is 99.6wt%, which is higher than the purity of E-HCFO-1233zd of Comparative Example 1 (99.5%wt); in addition, the operating temperature in Comparative Example 1 is much higher than that in Example 1.

[0108] Comparative Example 2:

[0109] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 2, except that:

[0110] In this comparative example, the extractant used in the extractive distillation is ethylenediamine.

[0111] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 10.

[0112] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 10.

[0113] Table 10 Tower operating conditions in comparative example 2

[0114] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 32.0 Tower top temperature / ℃ 31.1 Tower temperature / ℃ 120.4 Tower temperature / ℃ 134.9 Reflux ratio 8.0 Reflux ratio 5.3

[0115] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.2 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.1 wt %.

[0116] Compared with Comparative Example 2, under the same feeding conditions, the purity of HFC-245fa in Example 2 is 99.6wt%, which is higher than the purity of HFC-245fa in Comparative Example 2 (99.2wt%); the purity of E-HCFO-1233zd in Example 2 is 99.8wt%, which is higher than the purity of E-HCFO-1233zd in Comparative Example 2 (99.1wt%); in addition, the amount of extractant used in Comparative Example 2 is much higher than that in Example 2.

[0117] Comparative Example 3:

[0118] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 3, except that:

[0119] In this comparative example, the extractant used in the extractive distillation is ethylene glycol.

[0120] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 11.

[0121] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 11.

[0122] Table 11 Tower operating conditions in comparative example 3

[0123] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 32.0 Tower top temperature / ℃ 31.1 Tower temperature / ℃ 205.4 Tower temperature / ℃ 213.2 Reflux ratio 4.0 Reflux ratio 6.3

[0124] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 99.4 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.0 wt %.

[0125] Compared with Comparative Example 3, under the same feeding conditions, the purity of HFC-245fa in Example 3 is 99.6wt%, which is higher than the purity of HFC-245fa in Comparative Example 3 (99.4wt%); the purity of E-HCFO-1233zd in Example 3 is 99.5wt%, which is higher than the purity of E-HCFO-1233zd in Comparative Example 3 (99.0wt%); in addition, the amount of extractant used in Comparative Example 3 is much higher than that in Example 3.

[0126] Comparative Example 4:

[0127] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 4, except that:

[0128] In this comparative example, the extractant used in the extractive distillation is ethyl acetate.

[0129] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 12.

[0130] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 12.

[0131] Table 12 Tower operating conditions in comparative example 4

[0132]

[0133]

[0134] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 90.3 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.3 wt %.

[0135] Compared with Comparative Example 4, under the same feeding conditions, in Example 4, the mass fraction of HFC-245fa is 99.5wt%, which is higher than the purity of HFC-245fa of 90.3wt% in Comparative Example 4; the purity of E-HCFO-1233zd is 99.5wt%, which is higher than the purity of E-HCFO-1233zd of 99.3wt% in Comparative Example 4; in addition, the amount of extractant used in Comparative Example 4 is much higher than that in Example 4.

[0136] Comparative Example 5:

[0137] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 1, except that:

[0138] In this comparative example, the mass percentage of 1,1,1,3,3-pentafluoropropane in the raw material is 14.3%;

[0139] In this comparative example, the extractant used in the extractive distillation is a mixture of cyclopentane, carbon tetrachloride and acetone in a mass ratio of 1:1:1.

[0140] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 13.

[0141] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 13.

[0142] Table 13 Tower operating conditions in comparative example 5

[0143] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 33.4 Tower top temperature / ℃ 31.0 Tower temperature / ℃ 75.7 Tower temperature / ℃ 80.6 Reflux ratio 5.6 Reflux ratio 9.0

[0144] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 95.0 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 99.8 wt %.

[0145] As shown in Comparative Example 5, the purity of HFC-245fa is 95.0wt%, and the purity of E-HCFO-1233zd is 99.8wt%. This comparative example uses a mixture of multiple extractants, and only E-HCFO-1233zd in the product meets the industrial requirements (99.5wt%). Compared with the separation method involved in the present invention, that is, the purity of the products all meet the industrial requirements, it lacks economy and sustainability.

[0146] Comparative Example 6:

[0147] This comparative example provides a method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene. The method is basically the same as that in Example 1, except that:

[0148] In this comparative example, the mass percentage of 1,1,1,3,3-pentafluoropropane in the raw material is 50%.

[0149] In this comparative example, the extractant used in the extractive distillation is a mixture of cyclopentane, n-pentane, carbon tetrachloride and acetone in a mass ratio of 1:1:1:1.

[0150] In this comparative example, the operating conditions of the extractive distillation tower T1 in step 1 are shown in Table 14.

[0151] In this comparative example, the operating conditions of the extractant recovery tower T2 in step 2 are shown in Table 14.

[0152] Table 14 Tower operating conditions in comparative example 6

[0153] Extractive distillation tower T1 Extractant recovery tower T2 Operating pressure / kPa(A) 190 Operating pressure / kPa(A) 160 Tower top temperature / ℃ 33.4 Tower top temperature / ℃ 31.1 Tower temperature / ℃ 74.6 Tower temperature / ℃ 78.3 Reflux ratio 8.1 Reflux ratio 12.5

[0154] In this comparative example, the purity of HFC-245fa in the overhead product of the extractive distillation tower T1 was 95.3 wt % as determined by gas chromatography, and the purity of E-HCFO-1233zd in the overhead product of the extractant recovery tower T2 was 90.0 wt %.

[0155] As shown in Comparative Example 6, the purity of HFC-245fa is 95.3wt%, and the purity of E-HCFO-1233zd is 99.0wt%. In this example, a plurality of extractants are mixed, and the purity of HFC-245fa and E-HCFO-1233zd in the product does not meet the industrial requirement (99.5wt%). Compared with the separation method involved in the invention, the industrial value is weakened. At the same time, the method of mixing a plurality of extractants is easy to cause environmental pollution, lacking economy and sustainability.

Claims

1. A method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene, wherein the method separates 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene from a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene by extractive distillation, characterized in that: The extractant used in the extractive distillation is one or a combination of more than one of ester compounds, ether compounds and organic amine compounds.

2. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 1, characterized in that: The ester compound is an ester compound containing 9 to 13 carbon atoms.

3. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 2, characterized in that: The extractant is an ester compound containing 9 to 13 carbon atoms, such as octyl formate, isooctyl acetate, isopentyl valerate, isopropyl hexanoate or ethyl undecanoate.

4. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 1, characterized in that: The ether compound is an ether compound containing benzyl.

5. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 4, characterized in that: The benzyl-containing ether compound is benzyl methyl ether, benzyl propyl ether, benzyl butyl ether or benzyl isobutyl ether.

6. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 1, characterized in that: The organic amine compound is an organic amine compound containing 8 carbon atoms.

7. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 6, characterized in that: The organic amine compound containing 8 carbon atoms is N-methylheptylamine, N-ethylhexylamine, N-propylpentylamine or di-n-butylamine.

8. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to claim 1, characterized in that: The extractant is one or a combination of more than one of benzyl methyl ether, ethyl undecanoate and di-n-butylamine.

9. The method for separating 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: Step 1, using a mixture of 1,1,1,3,3-pentafluoropropane and trans-1-chloro-3,3,3-trifluoropropene as a raw material, wherein the mass percentage of 1,1,1,3,3-pentafluoropropane in the raw material is 6% to 10%; adding the raw material and the extractant into an extractive distillation tower (T1), wherein the mass ratio of the extractant to the raw material is (18 to 22):1, the top fraction of the extractive distillation tower (T1) is a 1,1,1,3,3-pentafluoropropane product, and the bottom fraction of the extractive distillation tower (T1) is trans-1-chloro-3,3,3-trifluoropropene and the extractant, and the operating conditions of the extractive distillation tower (T1) are: an operating pressure in the tower of 170 to 190 kPa, a top temperature of 28.9 to 31.9° C., a bottom temperature of 143.3 to 148.0° C., and a reflux ratio of 0.07 to 3.0; Step 2, the bottom fraction of the extractive distillation tower (T1) enters the extractant recovery tower (T2), the bottom fraction of the extractant recovery tower (T2) is the extractant, which is circulated to the extractive distillation tower (T1); the top fraction of the extractant recovery tower (T2) is trans-1-chloro-3,3,3-trifluoropropene; the operating conditions of the extractant recovery tower (T2) are: the operating pressure in the tower is 160-170 kPa, the top temperature is 31.0-32.9°C, the bottom temperature is 174.7-189.7°C, and the reflux ratio is 1.3-3.6.

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