Method for removing trifluoroacetone in hexafluoroisopropanol and device and application thereof

Abstract

The invention provides a method for removing trifluoroacetone in hexafluoroisopropanol and a device and application thereof, and relates to the technical field of extractive distillation, and the method comprises the following steps: spraying water downwards from the tower top of an extractive distillation tower as an extraction agent, enabling the extraction agent to be in contact with a hexafluoroisopropanol crude product for extraction so as to remove trifluoroacetone in the crude product, purified hexafluoroisopropanol is enriched at the tower top, and a mixture of trifluoroacetone, water and impurities is enriched at the tower kettle; wherein the temperature of the extractive distillation tower is 50-200 DEG C, and the reflux ratio is (1-100): 1. The technical problem that hexafluoroisopropanol (HFIP) and trifluoroacetone (TFK) are difficult to separate in the prior art is solved, and the technical effects that new substances are prevented from being introduced into a product system, the HFIP and the TFK can be effectively separated, a high-purity HFIP product is obtained, and meanwhile production energy consumption and wastewater discharge are reduced are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of extractive distillation, and in particular to a method for removing trifluoroacetone from hexafluoroisopropanol, a device and an application thereof. Background Art

[0002] Hexafluoroisopropanol (1,1,1,3,3,3-hexafluoroisopropanol, HFIP for short), molecular formula (CF3)2CHOH, molecular weight 168.04, CAS number 920-66-1, is a colorless transparent liquid. HFIP is an important fluorine-containing fine chemical that can be used to prepare high-end fluorine-containing fine chemicals such as anesthetics and surfactants; at the same time, HFIP has strong polarity, is easily miscible with water and many organic reagents, is heat-resistant and allows ultraviolet rays to pass through, etc. These characteristics make it an ideal solvent for many polymers; in addition, HFIP is also widely used in the organic synthesis of medicines and pesticides, and can also be used as a high-level cleaning agent in the manufacture and cleaning of cutting-edge instruments and equipment.

[0003] The synthesis method of hexafluoroisopropanol is mainly the hydrogenation reduction method using hexafluoroacetone as raw material. Hexafluoroacetone is catalytically hydrogenated under the action of a catalyst to synthesize hexafluoroisopropanol. This type of reaction is currently the main industrial method for producing hexafluoroisopropanol. According to the form of hexafluoroacetone, the current industrial equipment basically adopts the hydrogenation reduction method of hexafluoroacetone trihydrate. However, due to the selectivity of the catalyst during the hydrogenation reduction process, side reactions are inevitable. When HFIP is generated, a small amount of trifluoroacetone (TFK) will also be generated, and there will also be a small amount of unreacted hexafluoroacetone trihydrate.

[0004] Since HFIP is widely used in the downstream pharmaceutical field, it has very high requirements for purity, so it is particularly important to separate and purify HFIP. The small amount of hexafluoroacetone trihydrate contained in the crude reaction product has a huge difference in boiling point from HFIP, and can be well separated by ordinary distillation; however, TFK produced by the side reaction will form a certain azeotrope with HFIP, and the two are difficult to separate by ordinary distillation. It is particularly important to find an effective method to remove TFK from HFIP.

[0005] Chen Xianjin (Study on the Preparation of Hexafluoroisopropanol [D]. Zhejiang University, 2012.) investigated the selectivity of HFIP by exploring the single factor test of catalyst dosage and found that when the catalyst dosage is small, the byproduct trifluoroacetone is easily generated if the reaction time is too long; at the same time, the influence of catalyst type on the selectivity of HFIP was explored and it was found that palladium carbon catalyst has high activity but produces more byproduct trifluoroacetone. On the one hand, most hydrogenation reduction catalysts are precious metal catalysts and are expensive; on the other hand, the precious metal loading is difficult to accurately control; therefore, it is extremely difficult to reduce the production of byproduct trifluoroacetone by changing catalyst and other conditions. In addition, the document reports a method for removing trifluoroacetone by chemical reaction, by adding hydrazine hydrate to the crude HFIP reaction product, and removing trifluoroacetone by reaction; however, the amount of hydrazine hydrate in this method cannot be accurately controlled. When it is too little, trifluoroacetone cannot be completely reacted, and when it is too much, new impurities will be introduced; in addition, the reaction of hydrazine hydrate with trifluoroacetone generates new nitrogen-containing high-boiling products, which also need to be separated again, which undoubtedly increases the separation cost.

[0006] Prior art CN200580008674.5 reports four methods for separating TFK from HFIP. Method 1 is to subject the reaction product to another 2% palladium-carbon catalyst for further hydrogen reduction, and to separate the obtained product by distillation again to remove TFK; Method 2 is to cool the reaction product to -4°C~-78°C. Since the freezing point of TFK is -78°C and the freezing point of HFIP is -4.4°C, when the temperature is lowered, HFIP is frozen but TFK is not frozen, thereby separating the two phases; Method 3 is to add hydrofluoric acid to the reaction product so that the hydrofluoric acid and TFK form a high boiling point mixture to achieve separation; Method 4 is to separate HFIP and TFK under acid-free conditions by forming an azeotrope. Among the above four methods, the first method requires a secondary hydrogenation reduction reaction, and excessive hydrogenation may produce other impurities, and the catalyst is still a precious metal catalyst, so the process is cumbersome and the cost is high; the second method is difficult to separate by physical freezing because the TFK content in the reaction product is often very small; the third method requires the introduction of hydrofluoric acid. Although trace HF will be generated as a side reaction during the hydrogenation reduction process, the introduction of hydrofluoric acid will make the system extremely acidic and corrosive, increasing the safety risk, and subsequent measures for removing HF need to be considered, which is cumbersome and dangerous; the fourth method does not explain how to separate the mixture of HFIP and TFK, so it has no reference value.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] One of the purposes of the present invention is to provide a method for removing trifluoroacetone from hexafluoroisopropanol, which has a simple process and is easy to operate, can avoid introducing new substances into the product system, and can effectively separate HFIP and TFK, which is conducive to obtaining a high-purity HFIP product.

[0009] The second object of the present invention is to provide a device for removing trifluoroacetone from hexafluoroisopropanol, which is not only easy to operate, but also has low energy consumption, less wastewater discharge, and can effectively separate HFIP and TFK.

[0010] The third object of the present invention is to provide an application of a method for removing trifluoroacetone from hexafluoroisopropanol, which is beneficial to obtaining a high-purity HFIP product and can achieve outstanding application effects.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: In a first aspect, a method for removing trifluoroacetone from hexafluoroisopropanol comprises the following steps: Spraying water as an extractant from the top of the extractive distillation tower, so that the extractant contacts with the crude hexafluoroisopropanol product to extract and remove trifluoroacetone in the crude product, wherein the purified hexafluoroisopropanol is enriched at the top of the tower, and a mixture of trifluoroacetone, water and impurities is enriched at the bottom of the tower; The temperature of the extractive distillation tower is 50°C~200°C, and the reflux ratio is (1~100):1.

[0012] Furthermore, the pressure of the extractive distillation tower is 0-0.5 MPa; Preferably, the impurities include hexafluoroacetone.

[0013] Furthermore, the mass ratio of hexafluoroisopropanol to trifluoroacetone in the crude hexafluoroisopropanol is (50-20000):1, preferably (99-10000):1.

[0014] Furthermore, the mass ratio of the extractant to the crude hexafluoroisopropanol feed is (1-200):1, preferably (5-200):1.

[0015] Furthermore, the purity of the purified hexafluoroisopropanol is above 99.99%.

[0016] Furthermore, the method further comprises the following steps: The mixture of trifluoroacetone, water and hexafluoroacetone is discharged to an extraction recovery tower for separation, trifluoroacetone is enriched at the top of the tower, and water and hexafluoroacetone are enriched in the bottom of the tower.

[0017] In a second aspect, a device for implementing any of the above methods comprises an extractive distillation tower and a tower top condenser and a tower bottom heat source; A feed pipeline for crude hexafluoroisopropanol is provided at the lower part of the extractive distillation tower; A hexafluoroisopropanol receiving pipeline is arranged on the top of the extractive distillation tower.

[0018] Furthermore, the bottom discharge pipe of the extractive distillation tower is connected to the extraction recovery tower, so that the mixture enriched in the bottom of the extractive distillation tower enters the extraction recovery tower for separation.

[0019] Furthermore, the bottom discharge pipe of the extraction recovery tower is connected to the upper part of the extraction distillation tower, so as to allow the water enriched in the bottom of the extraction recovery tower to be recycled into the extraction distillation tower.

[0020] A third aspect is an application of any of the methods described above in the production of hexafluoroisopropanol.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: The method for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention uses water as an extractant, has the advantages of being widely available and inexpensive; at the same time, no new substances are introduced into the product system, and the technical problem of difficulty in separating hexafluoroisopropanol (HFIP) and trifluoroacetone (TFK) in the prior art is effectively solved; in addition, the separation process of the method of the present invention is simple, and the complicated processes additionally brought about by other physical methods and chemical methods are avoided; and the components enriched in the bottom of the tower can be further reused and recovered through ordinary separation, which reduces production energy consumption, reduces wastewater discharge, and saves costs; in short, under the coordinated cooperation of each step and its process parameters, the HFIP product obtained after separation by the method of the present invention has high purity, which can reach more than 99.99%, and the TFK content is stably controlled within 10ppm.

[0022] The device for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention is not only easy to operate, but also has low energy consumption and less wastewater discharge, and can effectively separate HFIP and TFK.

[0023] The application of the method for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention is conducive to obtaining a high-purity HFIP product and can achieve outstanding application effects. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic structural diagram of an apparatus for removing trifluoroacetone from hexafluoroisopropanol provided in one embodiment of the present invention.

[0025] Icons: 1-extraction distillation tower; 2-extraction recovery tower; 3-extraction distillation tower steam regulating valve; 4-extraction recovery tower steam regulating valve; 5-extraction agent delivery pump; 6-extraction distillation tower condenser; 7-extraction recovery tower condenser; 8-extraction distillation tower safety valve; 9-extraction recovery tower safety valve; 10-extraction distillation tower receiving regulating valve; 11-extraction recovery tower receiving regulating valve; 12-feeding pipeline for crude hexafluoroisopropanol; 13-extraction agent addition pipeline; 14-extraction recovery tower kettle discharge pipeline; 15-hexafluoroisopropanol receiving pipeline; 16-relatively light component discharge pipeline. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] According to a first aspect of the present invention, there is provided a method for removing trifluoroacetone from hexafluoroisopropanol, comprising the following steps: Spraying water as an extractant from the top of the extractive distillation tower, so that the extractant contacts with the crude hexafluoroisopropanol product to extract and remove trifluoroacetone in the crude product, wherein the purified hexafluoroisopropanol is enriched at the top of the tower, and a mixture of trifluoroacetone, water and impurities is enriched at the bottom of the tower; At the same time, the temperature of the extractive distillation tower is 50°C~200°C, and the reflux ratio is (1~100):1.

[0028] It should be noted that the crude hexafluoroisopropanol refers to the product system obtained by the hydrogenation reduction of hexafluoroacetone trihydrate, which contains trifluoroacetone as a by-product; water is also produced in the hydrogenation reduction of hexafluoroacetone trihydrate; the present invention removes trifluoroacetone by extracting and rectifying with water to prepare high-purity hexafluoroisopropanol, which can avoid introducing new substances into the product system and can well separate hexafluoroisopropanol and trifluoroacetone; in addition, the components enriched in the bottom of the tower (trifluoroacetone, water and a small amount of unreacted hexafluoroacetone trihydrate) can be recovered by ordinary separation to realize the recovery of hexafluoroacetone trihydrate, so it is beneficial to reduce production energy consumption, reduce wastewater discharge and save costs.

[0029] The method for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention uses water as an extractant, has the advantages of being widely available and inexpensive; at the same time, no new substances are introduced into the product system, and the technical problem of difficulty in separating hexafluoroisopropanol (HFIP) and trifluoroacetone (TFK) in the prior art is effectively solved; in addition, the separation process of the method of the present invention is simple, and the complicated processes additionally brought about by other physical methods and chemical methods are avoided; and the components enriched in the bottom of the tower can be further reused and recovered through ordinary separation, which reduces production energy consumption, reduces wastewater discharge, and saves costs; in short, under the coordinated cooperation of each step and its process parameters, the HFIP product obtained after separation by the method of the present invention has high purity, which can reach more than 99.99%, and the TFK content is stably controlled within 10ppm.

[0030] In the present invention, typical but non-limiting temperatures of the extractive distillation tower are, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C. Appropriate temperatures are more conducive to improving the effect of extracting and removing trifluoroacetone; if the temperature is too low, the amount of liquid phase descending in the extraction tower will be much greater than the amount of steam rising from the material, resulting in poor contact between the vapor and liquid on the tower plate, low tower efficiency, and poor separation effect; if the temperature is too high, the amount of evaporation in the tower bottom will increase, and contact with the descending liquid phase may cause flooding, resulting in a decrease in tower efficiency and poor separation, and at the same time, it will increase the load of the reboiler and condenser, resulting in energy waste.

[0031] In the present invention, typical but non-limiting reflux ratios of the extractive distillation tower are, for example, 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, and 100:1. An appropriate reflux ratio is more conducive to fully removing trifluoroacetone. If the reflux ratio is too low, the required equilibrium stage will increase. Under the condition of a certain height of the distillation tower (i.e., a certain theoretical stage), the separation effect is poor and the product quality is reduced. If the reflux ratio is too high, the liquid phase in the tower will increase, the concentration of the extractant will decrease, and the relative volatility between the components will decrease, which is equivalent to an increase in the theoretical stage of the distillation tower, a poor extraction effect, a decrease in product quality, and a waste of energy.

[0032] In the present invention, impurities include but are not limited to hexafluoroacetone.

[0033] In a preferred embodiment, the pressure of the extractive distillation tower can be 0-0.5 MPa, and typical but non-limiting pressures are, for example, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, and 0.5 MPa, which are more conducive to ensuring sufficient purification of hexafluoroisopropanol.

[0034] In the present invention, the mass ratio of hexafluoroisopropanol and trifluoroacetone in the crude hexafluoroisopropanol can be (50-20000):1, and its typical but non-limiting mass ratio is, for example, 50:1, 100:1, 500:1, 1000:1, 2000:1, 3000:1, 4000:1, 5000:1, 10000:1, 15000:1, 20000:1, and can be further preferably (99-10000):1.

[0035] In a preferred embodiment, the mass ratio of the extractant to the crude hexafluoroisopropanol feed can be (1-200):1, and typical but non-limiting mass ratios are, for example, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, and can be further preferably (5-200):1.

[0036] In a preferred embodiment, the purity of the purified hexafluoroisopropanol can reach above 99.99%, and the content of trifluoroacetone therein can be stably controlled within 10 ppm.

[0037] A typical method for removing trifluoroacetone from hexafluoroisopropanol comprises the following steps: Under the conditions of 50℃~200℃ and 0~0.5MPa (gauge pressure), the crude hexafluoroisopropanol product is introduced into an extractive distillation tower, and water is sprayed downward from the top of the tower to make the water and the crude hexafluoroisopropanol product fully contact for extraction. The reflux ratio of the extractive distillation tower is controlled to be (1~100): 1, and the top of the tower is enriched with more than 99.99% of high-purity hexafluoroisopropanol (HFIP) products, and the bottom of the tower is enriched with a mixture of trifluoroacetone, extractant water and a small amount of hexafluoroacetone trihydrate; A mixture of trifluoroacetone, extractant water and a small amount of hexafluoroacetone trihydrate is discharged from the bottom of the extractive distillation tower to an extraction recovery tower, and is recovered to obtain hexafluoroacetone trihydrate through ordinary separation in the extraction recovery tower; wherein, trifluoroacetone is enriched at the top of the tower; and a mixture of extractant water and hexafluoroacetone trihydrate is enriched in the bottom of the tower, and can be further distilled and separated to obtain relatively concentrated hexafluoroacetone trihydrate.

[0038] According to a second aspect of the present invention, there is provided an apparatus for implementing any of the above methods, comprising an extractive distillation tower and a tower top condenser and a tower bottom heat source; A feed pipeline for the crude hexafluoroisopropanol is provided at the lower part of the extractive distillation tower; A hexafluoroisopropanol receiving pipeline is arranged on the top of the extractive distillation tower.

[0039] The device for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention is not only easy to operate, but also has low energy consumption and less wastewater discharge, and can effectively separate HFIP and TFK.

[0040] In a preferred embodiment, the bottom discharge pipe of the extractive distillation tower is connected to the extraction recovery tower, so that the mixture enriched in the bottom of the extractive distillation tower enters the extraction recovery tower for separation.

[0041] In a preferred embodiment, the bottom discharge pipe of the extraction recovery tower is connected to the upper part of the extraction distillation tower, so as to allow the extractant enriched in the bottom of the extraction recovery tower to be recycled to the extraction distillation tower.

[0042] A typical structure of a device for removing trifluoroacetone from hexafluoroisopropanol is shown in Figure 1 , comprising an extractive distillation tower 1, an extractive distillation tower condenser 6 arranged at the top of the tower, and a heat source arranged at the bottom of the tower; The extractive distillation tower 1 can separate TFK from HFIP under the action of the extractant, and enrich high-purity HFIP at the top of the tower, while TFK is absorbed by the extractant and enriched in the tower bottom; the extractive distillation tower condenser 6 uses circulating water as a refrigerant; at the same time, 0.35Mpa steam is used as a heat source in its tower bottom; A feed pipeline 12 for the crude hexafluoroisopropanol is provided at the lower part of the extractive distillation tower 1; The top of the extractive distillation tower 1 is also provided with an extractive distillation tower safety valve 8; Meanwhile, the extractive distillation tower 1 is provided with a hexafluoroisopropanol receiving pipeline 15 at the top, and the hexafluoroisopropanol receiving pipeline 15 is provided with an extractive distillation tower receiving regulating valve 10; An extractive distillation tower steam regulating valve 3 is provided on the tower kettle of the extractive distillation tower 1; The bottom discharge pipe of the extractive distillation tower 1 is connected to the extraction recovery tower 2, so as to allow the mixture enriched in the bottom of the extractive distillation tower to enter the extraction recovery tower for separation. The extraction recovery tower collects TFK and a small amount of extractant at the top of the tower, and collects the extractant and hexafluoroacetone trihydrate in the bottom of the tower. The top of the extraction recovery tower 2 is provided with an extraction recovery tower condenser 7 and a relatively light component discharge pipeline 16, and the relatively light component discharge pipeline 16 is provided with an extraction recovery tower receiving regulating valve 11; The top of the extraction recovery tower 2 is also provided with an extraction recovery tower safety valve 9; The tower bottom discharge pipe 14 of the extraction recovery tower is connected to the upper part of the extraction distillation tower 1, so as to allow the extractant enriched in the tower bottom of the extraction recovery tower to be recycled to the extraction distillation tower; An extraction recovery tower steam regulating valve 4 is provided on the tower kettle of the extraction recovery tower 2; The tower bottom discharge pipeline of the extraction recovery tower 2 is provided with an extractant delivery pump 5 and an extractant supplement pipeline 13 .

[0043] According to a third aspect of the present invention, there is provided an application of any of the above methods in the production of hexafluoroisopropanol.

[0044] The application of the method for removing trifluoroacetone from hexafluoroisopropanol provided by the present invention is conducive to obtaining a high-purity HFIP product and can achieve outstanding application effects. The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0045] Example 1 A method for removing trifluoroacetone (TFK) from hexafluoroisopropanol (HFIP), comprising the following steps: At 100°C and 0.1MPa (gauge pressure), crude hexafluoroisopropanol (HFIP to TFK mass ratio of 250:1) was introduced into an extractive distillation tower, and water was sprayed from the top of the tower as an extractant (the mass ratio of water to crude hexafluoroisopropanol feed was 6:1) to allow water to fully contact with the crude hexafluoroisopropanol for extraction. The reflux ratio of the extractive distillation tower was controlled to be 30:1. The HFIP product enriched and purified at the top of the tower had a purity of 99.991% and a TFK content of 9ppm. A mixture of TFK, water and impurities (hexafluoroacetone) is concentrated in the bottom of the tower.

[0046] Example 2 A method for removing trifluoroacetone (TFK) from hexafluoroisopropanol (HFIP), comprising the following steps: At 100°C and 0.1MPa (gauge pressure), crude hexafluoroisopropanol (HFIP to TFK mass ratio of 300:1) was introduced into an extractive distillation tower, and water was sprayed from the top of the tower as an extractant (the mass ratio of water to crude hexafluoroisopropanol feed was 8:1) to allow water to fully contact with the crude hexafluoroisopropanol for extraction. The reflux ratio of the extractive distillation tower was controlled at 20:1. The HFIP product enriched and purified at the top of the tower had a purity of 99.992% and a TFK content of 5ppm. A mixture of TFK, water and impurities (hexafluoroacetone) is concentrated in the bottom of the tower.

[0047] Example 3 A method for removing trifluoroacetone (TFK) from hexafluoroisopropanol (HFIP), comprising the following steps: At 100°C and 0.06MPa (gauge pressure), crude hexafluoroisopropanol (HFIP to TFK mass ratio is 200:1) is introduced into an extractive distillation tower, and water is sprayed from the top of the tower as an extractant (the mass ratio of water to crude hexafluoroisopropanol feed is 10:1) to allow water to fully contact with the crude hexafluoroisopropanol for extraction. The reflux ratio of the extractive distillation tower is controlled to be 15:1. The HFIP product enriched and purified at the top of the tower has a purity of 99.993% and a TFK content of 2ppm. A mixture of TFK, water and impurities (hexafluoroacetone) is concentrated in the bottom of the tower.

[0048] Example 4 A method for removing trifluoroacetone (TFK) from hexafluoroisopropanol (HFIP), comprising the following steps: At 100°C and 0.05MPa (gauge pressure), crude hexafluoroisopropanol (HFIP to TFK mass ratio is 100:1) is introduced into an extractive distillation tower, and water is sprayed from the top of the tower as an extractant (the mass ratio of water to crude hexafluoroisopropanol feed is 15:1) to allow water to fully contact with the crude hexafluoroisopropanol for extraction. The extractive distillation tower controls the reflux ratio to be 10:1, and the HFIP product enriched and purified at the top of the tower has a purity of 99.99% and a TFK content of 10ppm. A mixture of TFK, water and impurities (hexafluoroacetone) is concentrated in the bottom of the tower.

[0049] Example 5 The difference between this embodiment and embodiment 1 is that the temperature condition of the operation of the extractive distillation tower in this embodiment is 60°C; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.991% and a TFK content of 10 ppm.

[0050] Example 6 The difference between this embodiment and embodiment 1 is that the temperature condition for operating the extractive distillation tower in this embodiment is 150°C; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.992% and a TFK content of 6 ppm.

[0051] Example 7 The difference between this embodiment and embodiment 1 is that the temperature condition of the operation of the extractive distillation tower in this embodiment is 200°C; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.99% and a TFK content of 9 ppm.

[0052] Example 8 The difference between this embodiment and embodiment 1 is that the reflux ratio of the extractive distillation tower in this embodiment is controlled to be 1:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.99% and a TFK content of 10 ppm.

[0053] Example 9 The difference between this embodiment and embodiment 1 is that the reflux ratio of the extractive distillation tower in this embodiment is controlled to be 50:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.991% and a TFK content of 8 ppm.

[0054] Example 10 The difference between this embodiment and embodiment 1 is that the reflux ratio of the extractive distillation tower in this embodiment is controlled to be 100:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.99% and a TFK content of 10 ppm.

[0055] Embodiment 11 The difference between this embodiment and embodiment 1 is that in this embodiment, the ratio of the amount of extractant in the extractive distillation tower to the amount of crude hexafluoroisopropanol fed is 5:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.99% and a TFK content of 9 ppm.

[0056] Example 12 The difference between this embodiment and embodiment 1 is that in this embodiment, the ratio of the amount of extractant in the extractive distillation tower to the amount of crude hexafluoroisopropanol fed is 15:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 99.991% and a TFK content of 8 ppm.

[0057] Comparative Example 1 The difference between this comparative example and Example 1 is that the temperature condition of the operation of the extractive distillation tower in this comparative example is 30°C; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 95.81% and a TFK content of 309 ppm.

[0058] Comparative Example 2 The difference between this comparative example and Example 1 is that the reflux ratio of the extractive distillation tower in this comparative example is controlled to be 130:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 98.82% and a TFK content of 207 ppm.

[0059] Compared with Example 1, the defect of this comparative example is that the reflux ratio is too large, the concentration of the extractant in the distillation tower is diluted and reduced, the relative volatility between the components is reduced, and the extraction effect is deteriorated.

[0060] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, the ratio of the amount of extractant in the extractive distillation tower to the amount of crude hexafluoroisopropanol fed is 1:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 97.02% and a TFK content of 507 ppm.

[0061] Compared with Example 1, the defect of this comparative example is that the ratio of the extractant dosage to the feed amount of crude hexafluoroisopropanol is too low, the concentration of the extractant in the distillation tower is too low, the relative volatility between the components is reduced, and the extraction effect is deteriorated.

[0062] Comparative Example 4 The difference between this comparative example and Example 1 is that in this comparative example, the ratio of the amount of extractant in the extractive distillation tower to the amount of crude hexafluoroisopropanol fed is 20:1; The rest is the same as in Example 1. The HFIP product enriched and purified at the top of the tower has a purity of 96.72% and a TFK content of 492 ppm.

[0063] Compared with Example 1, the defect of this comparative example is that the ratio of the extractant dosage to the feed amount of the crude hexafluoroisopropanol is too large, the extractant concentration in the distillation tower is too high, and the extractant is brought into the product as a heavy component, resulting in unqualified product quality; in addition, the extractant is a high-boiling point substance, and too high a content in the tower will greatly increase the heat load of the distillation tower.

[0064] It can be seen that the method for removing trifluoroacetone from hexafluoroisopropanol of the present invention uses water as an extractant, not only does not introduce new substances into the product system, but also has a simple process and is easy to operate, and effectively solves the technical problem of difficulty in separating hexafluoroisopropanol (HFIP) and trifluoroacetone (TFK) in the prior art; in short, under the coordinated cooperation of various steps and parameters, the HFIP product purified by the method of the present invention has a high purity, which can reach more than 99.99%, and the TFK content is stably controlled within 10ppm.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for removing trifluoroacetone from hexafluoroisopropanol, characterized in that: The following steps are involved: Spraying water as an extractant from the top of the extractive distillation tower, so that the extractant contacts with the crude hexafluoroisopropanol product to extract and remove trifluoroacetone in the crude product, wherein the purified hexafluoroisopropanol is enriched at the top of the tower, and a mixture of trifluoroacetone, water and impurities is enriched at the bottom of the tower; The temperature of the extractive distillation tower is 50°C~200°C, and the reflux ratio is (1~100):

1.

2. The method according to claim 1, characterized in that The pressure of the extractive distillation tower is 0-0.5 MPa; The impurities include hexafluoroacetone.

3. The method according to claim 2, characterized in that The mass ratio of hexafluoroisopropanol to trifluoroacetone in the crude hexafluoroisopropanol is (50-20000):

1.

4. The method according to claim 1, characterized in that The mass ratio of the extractant to the crude hexafluoroisopropanol feed is (1-200):

1.

5. The method according to claim 1, characterized in that The purity of the purified hexafluoroisopropanol is above 99.99%.

6. The method according to claim 2, characterized in that The method further comprises the following steps: The mixture of trifluoroacetone, water and hexafluoroacetone is discharged to an extraction recovery tower for separation, trifluoroacetone is enriched at the top of the tower, and water and hexafluoroacetone are enriched in the bottom of the tower.

7. A device for implementing the method according to any one of claims 1 to 6, characterized in that: It includes an extractive distillation tower and its top condenser and tower kettle heat source; A feed pipeline for crude hexafluoroisopropanol is provided at the lower part of the extractive distillation tower; A hexafluoroisopropanol receiving pipeline is arranged on the top of the extractive distillation tower.

8. The device according to claim 7, characterized in that The tower bottom discharge pipe of the extractive distillation tower is connected to the extraction recovery tower, so as to allow the mixture enriched in the tower bottom of the extractive distillation tower to enter the extraction recovery tower for separation.

9. The device according to claim 8, characterized in that The tower bottom discharge pipe of the extraction recovery tower is connected to the upper part of the extraction distillation tower, so as to allow the water enriched in the tower bottom of the extraction recovery tower to be recycled to the extraction distillation tower.

10. Use of the method according to any one of claims 1 to 6 in the production of hexafluoroisopropanol.

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