阅读说明：本技术 一种以多孔液体为萃取剂分离二氟乙醇和水的方法 (Method for separating difluoroethanol and water by taking porous liquid as extracting agent ) 是由 徐冬梅 吴绪敏 马艺心 于 2020-12-21 设计创作，主要内容包括：本发明涉及一种利用多孔液体萃取分离二氟乙醇和水的方法,该方法是利用ZIF-8和疏水离子液体合成多孔液体,并以多孔液体为萃取剂,萃取分离二氟乙醇和水的混合物。首先对混合后的多孔液体与二氟乙醇和水进行搅拌,静置后得到分层的两相；通过分液的方式分离出上层萃余相和下层萃取相。然后用乙酸乙酯对下层萃取相进行反萃取,并将反萃后的反萃取相进行精馏处理后得到二氟乙醇；将上层萃余相用再生的多孔液体进行循环萃取。本发明所使用的多孔液体兼具多孔材料和离子液体的特性,分离效率高、循环萃取能力强、环境友好且可以重复使用。(The invention relates to a method for extracting and separating difluoroethanol and water by utilizing porous liquid, which is characterized in that ZIF-8 and hydrophobic ionic liquid are utilized to synthesize the porous liquid, and the porous liquid is used as an extracting agent to extract and separate a mixture of difluoroethanol and water. Firstly, stirring the mixed porous liquid, difluoroethanol and water, and standing to obtain two layered phases; separating the upper raffinate phase and the lower extract phase by a liquid separation mode. Then, carrying out back extraction on the lower extraction phase by using ethyl acetate, and rectifying the back extraction phase after back extraction to obtain difluoroethanol; and circularly extracting the upper raffinate phase by using regenerated porous liquid. The porous liquid used in the invention has the characteristics of both porous materials and ionic liquid, and has the advantages of high separation efficiency, strong circulating extraction capacity, environmental friendliness and reusability.)

1. A method for separating difluoroethanol and water by taking porous liquid as an extracting agent is characterized by comprising the following steps: (1) putting 2-5 g of hydrophobic ionic liquid and 0.03-0.06 g of ZIF-8 into a small centrifugal tube, and carrying out ultrasonic treatment in an ultrasonic cleaning machine for 20-40 minutes to synthesize porous liquid;

(2) adding porous liquid (the mass ratio of the porous liquid to the mixture of difluoroethanol and water is 0.5-5: 1) into the mixture of difluoroethanol and water, stirring at 25-45 ℃ for 30-120min, and standing until two phases are layered to obtain an upper raffinate phase and a lower extract phase; the upper extraction raffinate phase can be extracted circularly;

(3) adding 2-5 g of reverse extraction reagent ethyl acetate into the lower extraction phase obtained in the step (2), stirring in a beaker for 30-120min, standing for 30-40 min to obtain a reverse extraction reagent phase containing difluoroethanol at the upper layer and a porous liquid phase at the lower layer;

(4) rectifying the back extraction reagent phase containing difluoroethanol obtained in the step (3) to obtain difluoroethanol and a back extraction reagent, wherein the back extraction reagent is reused;

(5) and (4) drying the porous liquid phase obtained in the step (3) in a vacuum drying oven for 12-24h to obtain regenerated porous liquid which can be used for circulating extraction of the upper raffinate phase in the step (2).

2. The method for separating difluoroethanol and water by extraction with a porous liquid as claimed in claim 1, wherein the hydrophobic ionic liquid is pyridyl bis (trifluoromethanesulfonimide), imidazolyl bis (trifluoromethanesulfonimide) and [ DBU-PEG ] bis (trifluoromethanesulfonimide).

3. The method for separating difluoroethanol and water by extraction with a porous liquid as claimed in claim 1, wherein the number of the cyclic extraction is 5 to 10.

4. The method for separating difluoroethanol and water by extraction with a porous liquid as claimed in claim 1, wherein the recovery rate of difluoroethanol obtained by the separation is 91.6%.

Technical Field

The invention relates to a method for extracting and separating difluoroethanol and water by utilizing porous liquid, belonging to the technical field of chemical separation.

Background

Difluoroethanol (DFE) is an important fluorochemical aliphatic intermediate. Due to its special structure, difluoromethyl has different chemical properties from other alcohols and can participate in a variety of organic synthetic reactions, particularly in fluorine-containing pesticides, pharmaceuticals, fluoropolymers, and cleaning agents. Aqueous solutions of DFE are produced during the use and preparation of difluoroethanol. DFE and water can form an azeotrope. Difluoroethanol is very similar in polarity to water and is more difficult to separate than azeotropic systems of fluoroalcohol compounds such as tetrafluoropropanol and octafluoropentanol and water. Liquid-liquid extraction is a common method for separating azeotropes, and is carried out at room temperature and atmospheric pressure. Because ZIF-8 has a special pore structure, the ZIF-8 has the effect of adsorbing alcohol, but the ZIF-8 is a solid and has some defects compared with a liquid route in the aspects of adsorption and separation, such as difficult mass transfer, unfavorable heat transfer and the like, and the porous liquid is a novel material with a flowing and permanent pore structure, combines the characteristics of the microporous solid such as size, shape selectivity, adsorption and the like and the rapid mass transfer, flowing and stable dynamic performance of the liquid, and has potential application values in the aspects of separation, catalysis and the like.

The patent (CN 102304024A) relates to a method for separating difluoroethanol and water by azeotropic distillation, wherein azeotropic agent toluene is added to form an azeotrope of toluene and water to remove most of water, and then the difluoroethanol is obtained by distillation.

The patent (CN 106810421 a) relates to the separation of a mixture of difluoroethanol and water by a coupled rectification and pervaporation process, and the separation of difluoroethanol is carried out by a coupled rectification and pervaporation technology.

The above-mentioned prior art separation techniques have the following drawbacks and disadvantages: (1) the difluoroethanol and the water are separated by the extractive distillation and the azeotropic distillation, the equipment cost is high, and the energy consumption is large. (2) The entrainer toluene is toxic, affects human health, is flammable and explosive, and poses a threat to the safety and health of operators. (3) The addition of the entrainer leads the product to contain the entrainer, and influences the application of the difluoroethanol in the aspects of medicines and cleaning agents.

Disclosure of Invention

Technical problem to be solved

The invention provides a method for separating difluoroethanol and water by taking porous liquid as an extractant, aiming at the defects and shortcomings in the prior art, wherein the method is high in product purity and simple to operate. Technical scheme

The purpose of the invention is realized by the following technical scheme.

A method for separating difluoroethanol and water by taking porous liquid as an extracting agent is characterized by comprising the following steps: (1) putting 2-5 g of hydrophobic ionic liquid and 0.03-0.06 g of ZIF-8 into a small centrifugal tube, and carrying out ultrasonic treatment in an ultrasonic cleaning machine for 20-40 minutes to synthesize porous liquid;

(2) adding porous liquid (the mass ratio of the porous liquid to the mixture of difluoroethanol and water is 0.5-5: 1) into the mixture of difluoroethanol and water, stirring at 25-45 ℃ for 30-120min, and standing until two phases are layered to obtain an upper raffinate phase and a lower extract phase; the upper extraction raffinate phase can be extracted circularly;

(3) adding 2-5 g of reverse extraction reagent ethyl acetate into the lower extraction phase obtained in the step (2), stirring in a beaker for 30-120min, standing for 30-40 min to obtain a reverse extraction reagent phase containing difluoroethanol at the upper layer and a porous liquid phase at the lower layer;

(4) rectifying the back extraction reagent phase containing difluoroethanol obtained in the step (3) to obtain difluoroethanol and a back extraction reagent, wherein the back extraction reagent is reused;

(5) and (4) drying the porous liquid phase obtained in the step (3) in a vacuum drying oven for 12-24h to obtain regenerated porous liquid which can be used for circulating extraction of the upper raffinate phase in the step (2).

According to another preferred embodiment of the invention, characterized in that the hydrophobic ionic liquid is pyridyl bis-trifluoromethanesulfonimide, imidazolyl bis-trifluoromethanesulfonimide and [ DBU-PEG ] bis-trifluoromethanesulfonimide.

According to another preferred embodiment of the invention, the number of extraction cycles is between 5 and 10.

According to another preferred embodiment of the present invention, the recovery rate of difluoroethanol obtained by separation is 91.6%.

Advantageous effects

Compared with the prior art, the invention mainly has the following beneficial effects:

the method used by the invention has the advantages of low energy consumption, high extraction efficiency of the porous liquid extractant, stable property and strong cyclic extraction capability; the extracted porous liquid can be regenerated, the extraction agent can be reused, and the separation efficiency is hardly reduced.

Detailed description of the invention

The present invention will be described by way of the following examples, which illustrate a system for separating difluoroethanol and water using a hydrophobic porous liquid as an extractant, but the present invention is not limited to the following examples, and various embodiments are included in the technical scope of the present invention within the scope not departing from the gist of the invention described before and after.

Synthesis experiment of porous liquid: putting (2-5 g) hydrophobic ionic liquid and (0.03-0.06 g) ZIF-8 in a small centrifuge tube, carrying out ultrasonic treatment in an ultrasonic cleaning machine for 20-40 minutes to synthesize porous liquid, and observing that no obvious ZIF-8 is separated out, thereby indicating that the synthesis is successful.

Porous liquid extractant extraction separation experiment: measuring 1g of a mixture of difluoroethanol and water in a sample bottle with magnetons, adding 0.5-5 g of a porous liquid extractant, stirring for 30-120min, standing, absorbing a proper amount of upper extraction raffinate phase, carrying out quantitative analysis by a gas chromatograph, measuring the content of difluoroethanol before and after extraction, and calculating the extraction rate of the porous liquid on the difluoroethanol; carrying out back extraction on the obtained lower extraction phase by using ethyl acetate, stirring, standing for phase separation, carrying out cyclic extraction on the porous liquid obtained by lower separation, and continuously adding a mixture of difluoroethanol and water with the same mass ratio into the separated porous liquid for extraction; and rectifying the back-extraction agent phase of the upper layer after back extraction to obtain difluoroethanol, and calculating the recovery rate of the difluoroethanol.

The composition of the raffinate phase was analyzed by gas chromatography using a headspace automatic sampler, a packed column (3 mm. times.2 m), and a TCD detector (Lunan GC SP-6890). The sample peak areas were analyzed by the N2000 chromatographic workstation developed at university of zhejiang. Before analyzing the samples, the gas chromatograph was calibrated with a series of different standard mixtures, prepared with an analytical balance. The purity of hydrogen as carrier gas was 99.999%. The analytical temperatures were as follows: oven temperature 423.15K, detector temperature 443.15K, injection temperature 443.15K.

Example 1

The imidazole porous liquid is formed by combining 1-butyl-3-methylimidazole bistrifluoromethanesulfonimide and ZIF-8. The mass ratio of the porous liquid to the mixture of difluoroethanol and water is 0.5:1, the extraction temperature is 25 ℃, the stirring time is 30min, 2.55g of the porous liquid is taken out of a sample bottle, 5.1g of the mixture of difluoroethanol and water is added, the stirring is carried out for 30min, the standing is carried out for 30min, the difluoroethanol in the upper extraction raffinate phase is measured by adopting GC, the difluoroethanol extraction rate is 64.2 percent after the porous liquid is extracted for 10 times in a circulating way, the porous liquid in the lower extraction phase is recovered by ethyl acetate, the recovery rate of the difluoroethanol obtained after rectifying the back extraction agent phase is 83.3 percent, and the extraction rate is not obviously reduced after the porous liquid is extracted for 10 times in a circulating way.

Example 2

The pyridine porous liquid is formed by combining n-butylpyridine bis-trifluoromethanesulfonimide and ZIF-8, the mass ratio of the porous liquid to a mixture of difluoroethanol and water is 2:1, the extraction temperature is 25 ℃, the stirring time is 40min, at the temperature of 25 ℃, 5.045g of the mixture of difluoroethanol and water is put into a sample bottle, 10.09g of the porous liquid is added, the mixture is stirred for 40min and kept stand for 40min, the concentration of difluoroethanol in an upper extraction phase is measured by adopting GC, the porous liquid is extracted for 9 times in a circulating manner, the difluoroethanol extraction rate is 89.3%, the porous liquid in a lower extraction phase is recovered by using ethyl acetate, after rectifying an upper extraction agent phase, the recovery rate of difluoroethanol is 90.1%, and the extraction rate is not obviously reduced after the porous liquid is extracted for 9 times in a circulating manner.

Example 3

The pyridine porous liquid is formed by combining n-butylpyridine bis-trifluoromethanesulfonimide and ZIF-8, the mass ratio of the porous liquid to a mixture of difluoroethanol and water is 5:1, the extraction temperature is 35 ℃, the stirring time is 40min, 2g of the mixture of difluoroethanol and water is placed in a sample bottle at the temperature of 35 ℃, 10g of the porous liquid is added, the mixture is stirred for 40min and stands for 40min, the concentration of difluoroethanol in an upper extraction raffinate phase is measured by adopting GC, the porous liquid is extracted for 11 times in a circulating mode, the difluoroethanol extraction rate is 92.4%, the porous liquid in a lower extraction phase is recovered by using ethyl acetate, after an upper stripping agent phase is rectified, the recovery rate of difluoroethanol is 91.6%, and the extraction rate is not obviously reduced after the porous liquid is extracted for 11 times in a circulating mode.

Example 4

The imidazole porous liquid is formed by combining 1-butyl-3-methylimidazole bistrifluoromethanesulfonimide and ZIF-8. The mass ratio of the porous liquid to the mixture of difluoroethanol and water is 2:1, the extraction temperature is 45 ℃, the stirring time is 60min, 10.2g of the porous liquid is taken out of a sample bottle, 5.1g of the mixture of difluoroethanol and water is added, the stirring is carried out for 60min, the standing is carried out for 30min, the difluoroethanol in the upper extraction raffinate phase is measured by adopting GC, the porous liquid is extracted for 10 times in a circulating way, the difluoroethanol extraction rate is 88.3%, the porous liquid in the lower extraction phase is recovered by using ethyl acetate, the upper back extractant phase is rectified, the recovery rate of the difluoroethanol is 89.5%, and the extraction rate is not obviously reduced after the porous liquid is extracted for 10 times in a circulating way.

Example 5

The porous liquid is formed by combining [ DBU-FEG ] bis (trifluoromethanesulfonimide) and ZIF-8, the mass ratio of the porous liquid to a mixture of difluoroethanol and water is 1:1, the extraction temperature is 25 ℃, the stirring time is 30min, 5.1g of the porous liquid is put into a sample bottle, 5.1g of the mixture of difluoroethanol and water is added, the mixture is stirred for 30min and kept stand for 30min, difluoroethanol in an upper extraction residual phase is measured by adopting GC, the pore liquid is extracted for 8 times in a circulating manner, the difluoroethanol extraction rate is 85.4%, the porous liquid in a lower extraction phase is recovered by using ethyl acetate, the recovery rate of difluoroethanol is 89.5% after an upper back extraction agent phase is obtained, and the extraction rate is not obviously reduced after the porous liquid is extracted for 8 times in a circulating manner.

Example 6

The porous liquid is [ DBU-FEG ]][NTf₂]The method is characterized by comprising the steps of combining ionic liquid and ZIF-8, wherein the mass ratio of porous liquid to a mixture of difluoroethanol and water is 2:1, the extraction temperature is 35 ℃, the stirring time is 60min, 10.2g of porous liquid is put into a sample bottle, 5.1g of the mixture of difluoroethanol and water is added, the stirring is carried out for 120min, the standing is carried out for 30min, the difluoroethanol in an upper extraction raffinate phase is measured by adopting GC, the porous liquid is extracted for 8 times in a circulating manner, the difluoroethanol extraction rate is 86.7%, the porous liquid in a lower extraction phase is recovered by using ethyl acetate, the recovery rate of difluoroethanol obtained after rectifying an upper back extraction solvent phase is 87.5%, and the extraction rate is not obviously reduced after the porous liquid is extracted for 8 times in a circulating manner.