CN117285425A - Purification method of ethyl acetate - Google Patents

Abstract

The invention relates to the technical field of ethyl acetate production, in particular to a purification method of ethyl acetate; according to the ethyl acetate purifying method provided by the invention, water is separated from ethyl acetate by adopting a separation membrane to obtain ethyl acetate, and then ethyl acetate and ethanol are separated by utilizing a rectification technology; the purification method of ethyl acetate provided not only can effectively improve the yield of ethyl acetate; but also has the function of improving the purity of the ethyl acetate; the purification method of ethyl acetate provided by the invention has wider market prospect and is more suitable for popularization.

Description

A kind of purification method of ethyl acetate

Technical field

The invention relates to the technical field of ethyl acetate production, specifically a method for purifying ethyl acetate.

Background technique

Ethyl acetate, also known as ethyl acetate, is an organic compound, an ester with the functional group -COOR (a double bond between carbon and oxygen), which can undergo alcoholysis, ammonolysis, transesterification, reduction and other common ester processes. React together and are mainly used as solvents, flavorings, and cleaning and degreasing agents.

The content of commercially available ethyl acetate is generally 95 to 98%, and often contains trace amounts of water and ethanol, which requires purification of ethyl acetate. The existing purification method is to react crude ester (ethyl acetate-ethanol-water) mixture) as the raw material, the reaction crude ester is allowed to stand and the phase-separated oil phase is fed into the ethyl acetate refining tower, and the ethyl acetate product is obtained from the refining tower still. The above method uses molecular sieves to adsorb water impurities, but water impurities cannot be recycled and reused, and the molecular sieves need to be filtered after adsorbing water impurities, which affects the purification efficiency and degree of purification and cannot meet the demand.

Therefore, the present invention provides a method for purifying ethyl acetate to solve the above-mentioned related technical problems.

Contents of the invention

The object of the present invention is to provide a method for purifying ethyl acetate. The method for purifying ethyl acetate provided by the present invention uses a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate, and then utilize Distillation technology separates ethyl acetate and ethanol; the purification method of ethyl acetate provided can not only effectively increase the yield of ethyl acetate; but also has the effect of improving the purity of ethyl acetate.

In order to achieve the above objects, the present invention provides the following technical solutions:

The invention provides a method for purifying ethyl acetate, which includes the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.012 to 0.015 g/mL for 20 to 30 minutes; after the ultrasonic dispersion is completed, a potassium hexanitrocobaltate solution is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.018 to 0.022g/mL for 40 to 50 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution and stir for 12 to 13 hours at 120 to 140 r/min. Filter the solution to collect the filter cake, wash it with methanol 5 to 7 times, and stir at 80 to 70 times. Dry at 90°C for 12 hours, then grind to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.025 to 0.032 g/mL for 10 to 15 minutes; after the ultrasonic dispersion is complete, add polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C. , obtain the membrane solution;

The membrane solution will be applied on the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in the greenhouse to obtain the separation membrane;

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

A further configuration of the present invention is that in step I, the process of using a separation membrane to separate water from ethyl acetate is to vaporize the crude ethyl acetate to be treated and then dehydrate it in the gas phase through the separation membrane.

Further settings of the present invention are: when the gas phase state is dehydrated through the separation membrane, the operating temperature is 30~90°C, the operating pressure is 0.2~4.0kg, and the vacuum degree on the water permeable side is 80~3200Pa.

The present invention is further configured as follows: in the step I, when the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution 1: 0.8～0.7.

A further setting of the present invention is that in the step I, the added amount of the polyether block amide is 12 to 14% of the mass of n-butanol.

Further settings of the present invention are: in the step II, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed amount is 18.5 kmol/h, and the reflux ratio is 1.8 .

Further settings of the present invention are: in the step II, the number of theoretical plates of the solvent recovery tower is 2, the feed position is on the first plate, the feed amount is 15.2 kmol/h, and the reflux ratio is 1.2.

The present invention is further configured as follows: in the step II, the extraction agent is selected from any one of tetraethylammonium acetate, 1-ethyl-2,3-dimethylimidazole acetate, and tributylmethylammonium acetate. kind.

Compared with the prior art, the beneficial effects of the present invention are:

The purification method of ethyl acetate provided by the present invention uses a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate, and then uses distillation technology to separate ethyl acetate and ethanol; the ethyl acetate provided The purification method of ethyl acetate can not only effectively increase the yield of ethyl acetate; but also has the effect of improving the purity of ethyl acetate; the purification method of ethyl acetate provided by the present invention has broader market prospects and is more suitable for promotion.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a flow chart of the purification method of ethyl acetate of the present invention;

Figure 2 is a statistical diagram of the purified yield of ethyl acetate of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Embodiment 1: As shown in Figure 1, this embodiment provides a purification method of ethyl acetate, including the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.012 g/mL for 20 minutes; after the ultrasonic dispersion is completed, a solution of potassium hexanitrocobaltate is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.018g/mL for 40 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution, stir at 120r/min for 12h, filter the solution to collect the filter cake, wash it with methanol 5 times, and dry it at 80°C for 12h. Then grind it to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.025 g/mL for 10 minutes; after the ultrasonic dispersion is complete, add the polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C to obtain a membrane solution ;

The membrane solution will be applied to the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in a greenhouse to obtain a separation membrane.

Among them, when the gas phase state is dehydrated through the separation membrane, the operating temperature is 30°C, the operating pressure is 0.2kg, and the vacuum on the water permeable side is 80Pa.

When the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution is 1:0.8.

The addition amount of polyether block amide is 12% of the mass of n-butanol.

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

Among them, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed volume is 18.5 kmol/h, and the reflux ratio is 1.8.

The number of theoretical plates in the solvent recovery tower is 2, the feed position is on the first plate, the feed volume is 15.2 kmol/h, and the reflux ratio is 1.2.

The extraction agent was tetraethylammonium acetate.

Embodiment 2: As shown in Figure 1, this embodiment provides a purification method of ethyl acetate, including the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.013 g/mL for 22 minutes; after the ultrasonic dispersion is completed, a solution of potassium hexanitrocobaltate is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.019g/mL for 42 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution, stir at 125r/min for 12h, filter the solution to collect the filter cake, wash it with methanol 6 times, and dry it at 82°C for 12h. Then grind it to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.027 g/mL for 12 minutes; after the ultrasonic dispersion is complete, add the polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C to obtain a membrane solution;

The membrane solution will be applied to the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in a greenhouse to obtain a separation membrane.

Among them, when the gas phase state is dehydrated through the separation membrane, the operating temperature is 40°C, the operating pressure is 0.8kg, and the vacuum degree on the water permeable side is 1200Pa.

When the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution is 1:0.8 to 0.7.

The addition amount of polyether block amide is 12-14% of the mass of n-butanol.

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

Among them, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed volume is 18.5 kmol/h, and the reflux ratio is 1.8.

The number of theoretical plates in the solvent recovery tower is 2, the feed position is on the first plate, the feed volume is 15.2 kmol/h, and the reflux ratio is 1.2.

The extraction agent was 1-ethyl-2,3-dimethylimidazole acetate.

Embodiment 3: As shown in Figure 1, this embodiment provides a purification method of ethyl acetate, including the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.013g/mL for 25 minutes; after the ultrasonic dispersion is completed, a solution of potassium hexanitrocobaltate is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.020g/mL for 45 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution, stir at 130r/min for 13h, filter the solution to collect the filter cake, wash it with methanol 6 times, and dry it at 85°C for 12h. Then grind it to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.027 g/mL for 12 minutes; after the ultrasonic dispersion is complete, add the polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C to obtain a membrane solution;

The membrane solution will be applied to the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in a greenhouse to obtain a separation membrane.

Among them, when the gas phase state is dehydrated through the separation membrane, the operating temperature is 65°C, the operating pressure is 2.0kg, and the vacuum on the water permeable side is 2200Pa.

When the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution is 1:0.8.

The addition amount of polyether block amide is 13% of the mass of n-butanol.

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

Among them, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed volume is 18.5 kmol/h, and the reflux ratio is 1.8.

The number of theoretical plates in the solvent recovery tower is 2, the feed position is on the first plate, the feed volume is 15.2 kmol/h, and the reflux ratio is 1.2.

The extraction agent was tributyl methyl ammonium acetate.

Embodiment 4: As shown in Figure 1, this embodiment provides a purification method of ethyl acetate, including the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.014 g/mL for 28 minutes; after the ultrasonic dispersion is completed, a solution of potassium hexanitrocobaltate is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.021g/mL for 48 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution, stir at 135r/min for 13h, filter the solution to collect the filter cake, wash it with methanol 7 times, and dry it at 88°C for 12h. Then grind it to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.031 g/mL for 14 minutes; after the ultrasonic dispersion is complete, add the polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C to obtain a membrane. solution;

The membrane solution will be applied to the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in a greenhouse to obtain a separation membrane.

Among them, when the gas phase state is dehydrated through the separation membrane, the operating temperature is 80°C, the operating pressure is 3.0kg, and the vacuum on the water permeable side is 2200Pa.

When the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution is 1:0.8.

The addition amount of polyether block amide is 14% of the mass of n-butanol.

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

Among them, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed volume is 18.5 kmol/h, and the reflux ratio is 1.8.

The number of theoretical plates in the solvent recovery tower is 2, the feed position is on the first plate, the feed volume is 15.2 kmol/h, and the reflux ratio is 1.2.

The extraction agent was tetraethylammonium acetate.

Embodiment 5: As shown in Figure 1, this embodiment provides a purification method of ethyl acetate, including the following steps:

Ⅰ. Use a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate;

The preparation process of the separation membrane is as follows:

Ultrasonically disperse potassium hexanitrocobaltate in an appropriate amount of methanol at a solid-liquid ratio of 0.015 g/mL for 30 minutes; after the ultrasonic dispersion is completed, a solution of potassium hexanitrocobaltate is obtained;

Ultrasonically disperse dimethylimidazole in an appropriate amount of methanol at a solid-liquid ratio of 0.022g/mL for 50 minutes; after the ultrasonic dispersion is completed, a dimethylimidazole solution is obtained;

Add the potassium hexanitrocobaltate solution to the dimethylimidazole solution, stir at 140r/min for 13h, filter the solution to collect the filter cake, wash it with methanol 7 times, and dry it at 90°C for 12h. Then grind it to 200 mesh to obtain the filler;

Ultrasonically disperse the filler in an appropriate amount of n-butanol at a solid-liquid ratio of 0.032 g/mL for 15 minutes; after the ultrasonic dispersion is complete, add the polyether block amide and continue ultrasonic dispersion for 6 hours at 75°C to obtain a membrane solution;

The membrane solution will be applied to the MFI filter membrane, and then the membrane will be scraped, and the thickness of the scraped membrane will be controlled to 0.4mm. After the scraping is completed, it will be dried in a greenhouse to obtain a separation membrane.

Among them, when the gas phase state is dehydrated through the separation membrane, the operating temperature is 90°C, the operating pressure is 4.0kg, and the vacuum on the water permeable side is 3200Pa.

When the potassium hexanitrocobaltate solution is added to the dimethylimidazole solution, the mass ratio of the potassium hexanitrocobaltate solution and the dimethylimidazole solution is 1:0.7.

The addition amount of polyether block amide is 14% of the mass of n-butanol.

Ⅱ. Use distillation technology to separate ethyl acetate and ethanol to obtain purified ethyl acetate;

The process of utilizing distillation technology to separate ethyl acetate and ethanol is as follows:

The dehydrated ethyl acetate is fed from the middle section of the column still of the extractive distillation tower, and then the ethyl acetate is recovered from the top of the distillation tower;

The mixture of ethanol and extractant flows from the bottom of the rectification tower and flows into the solvent recovery tower, and the ethanol is distilled from the top of the solvent recovery tower;

The extractant flows out from the bottom of the solvent recovery tower and is cooled by the heat exchanger before returning to the extractive distillation tower for recycling.

Among them, the number of theoretical plates of the extractive distillation tower is 10, the feed position is on the fifth plate, the feed volume is 18.5 kmol/h, and the reflux ratio is 1.8.

The number of theoretical plates in the solvent recovery tower is 2, the feed position is on the first plate, the feed volume is 15.2 kmol/h, and the reflux ratio is 1.2.

The extraction agent was tetraethylammonium acetate.

Purification of ethyl acetate was carried out according to the methods of Example 1, Example 2, Example 3, Example 4 and Example 5 respectively, which were recorded as Example 1 group, Example 2 group, Example 3 group, Example 4 group and Example 5. Group, the existing method (CN112500292A) was used to purify ethyl acetate, which was recorded as the control group.

Record the purified yield of each group of ethyl acetate in Table 1.

It can be seen from Table 1 and Figure 2 that after testing, compared with the control group, the purification yield of ethyl acetate in Examples 1 to 5 was significantly higher than that of the control group ( P <0.05); and the differences between each example group were not the same. Not obvious. The above results show that the purification methods of ethyl acetate in Examples 1 to 5 have the effect of significantly improving the yield of purification of ethyl acetate.

Record the purified purity of each group of ethyl acetate in Table 2.

As can be seen from Table 2, after testing, compared with the control group, the purity of the purified ethyl acetate of Examples 1 to 5 was higher than that of the control group (P<0.05); and the difference between each example group was not obvious. The above results show that the purification methods of ethyl acetate in Examples 1 to 5 have the effect of further improving the purity of the purification of ethyl acetate.

It can be seen from the above that the purification method of ethyl acetate provided by the present invention uses a separation membrane to separate water from ethyl acetate to obtain dehydrated ethyl acetate, and then uses distillation technology to separate ethyl acetate and ethanol; The provided purification method of ethyl acetate can not only effectively increase the yield of ethyl acetate; but also has the effect of improving the purity of ethyl acetate. This shows that the purification method of ethyl acetate provided by the present invention has broader market prospects and is more suitable for promotion.

In the description of this specification, reference to the terms "one embodiment," "example," "specific example," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the invention. in an embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are only intended to help illustrate the invention. The preferred embodiments do not describe all details, nor do they limit the invention to the specific implementations described. Obviously, many modifications and variations are possible in light of the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention. The invention is limited only by the claims and their full scope and equivalents.

Claims (8)

1. A process for purifying ethyl acetate, comprising the steps of:

i, separating water from ethyl acetate by adopting a separation membrane to obtain dehydrated ethyl acetate;

the preparation process of the separation membrane is as follows:

ultrasonically dispersing potassium hexanitrocobaltate in a proper amount of methanol according to a solid-to-liquid ratio of 0.012-0.015 g/mL for 20-30 min; after ultrasonic dispersion is completed, obtaining a potassium hexanitrocobaltate solution;

ultrasonically dispersing the dimethylimidazole in a proper amount of methanol for 40-50 min according to the solid-liquid ratio of 0.018-0.022 g/mL; after ultrasonic dispersion is completed, obtaining a dimethyl imidazole solution;

adding a potassium hexanitrocobaltate solution into a dimethyl imidazole solution, stirring for 12-13 h under the condition of 120-140 r/min, filtering the solution to collect a filter cake, washing for 5-7 times with methanol, drying for 12h under the condition of 80-90 ℃, and grinding to 200 meshes to obtain a filler;

ultrasonically dispersing the filler in a proper amount of n-butyl alcohol for 10-15 min according to the solid-liquid ratio of 0.025-0.032-g/mL; after ultrasonic dispersion is finished, polyether block amide is added, and ultrasonic dispersion is continued for 6 hours at 75 ℃ to obtain a film solution;

coating a membrane solution on an MFI filter membrane, then scraping the membrane, controlling the thickness of the scraped membrane to be 0.4mm, and drying in a greenhouse after the membrane scraping is completed to obtain a separation membrane;

II, separating ethyl acetate and ethanol by using a rectification technology to obtain purified ethyl acetate;

the process for separating ethyl acetate from ethanol by using the rectification technology comprises the following steps:

feeding ethyl acetate which is dehydrated from the middle section of the tower kettle of the extraction rectifying tower, and recovering ethyl acetate from the top of the rectifying tower;

the mixture of the ethanol and the extractant flows into the solvent recovery tower after flowing out from the bottom of the rectifying tower, and the ethanol is distilled out from the top of the solvent recovery tower;

the extractant flows out from the bottom of the solvent recovery tower, is cooled by a heat exchanger and then returns to the extraction rectifying tower for recycling.

2. A process for purifying ethyl acetate according to claim 1, wherein: in the step I, the process of separating water from ethyl acetate by using a separation membrane is that the crude ethyl acetate to be treated is vaporized and then dehydrated in a gas phase state by using the separation membrane.

3. A process for purifying ethyl acetate according to claim 2, characterized in that: when the gas phase state is dehydrated through the separation membrane, the operation temperature is 30-90 ℃, the operation pressure is 0.2-4.0 kg, and the water permeable side vacuum degree is 80-3200 Pa.

4. A process for purifying ethyl acetate according to claim 1, wherein: in the step I, when the potassium hexanitrocobaltate solution is added into the dimethyl imidazole solution, the mass ratio of the potassium hexanitrocobaltate solution to the dimethyl imidazole solution is 1:0.8 to 0.7.

5. A process for purifying ethyl acetate according to claim 1, wherein: in the step I, the addition amount of the polyether block amide is 12-14% of the mass of the n-butanol.

6. A process for purifying ethyl acetate according to claim 1, wherein: in the step II, the theoretical plate number of the extractive distillation column is 10, the feeding position is 5 th plate, the feeding amount is 18.5kmol/h, and the reflux ratio is 1.8.

7. A process for purifying ethyl acetate according to claim 1, wherein: in the step II, the theoretical plate number of the solvent recovery tower is 2, the feeding position is 1 st plate, the feeding amount is 15.2kmol/h, and the reflux ratio is 1.2.

8. A process for purifying ethyl acetate according to claim 1, wherein: in the step II, the extractant is any one of tetraethylammonium acetate, 1-ethyl-2, 3-dimethyl imidazole acetate and tributyl ammonium methyl acetate.