CN111097190A - Method for extracting and recovering organic solvent by ionic liquid - Google Patents
Method for extracting and recovering organic solvent by ionic liquid Download PDFInfo
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Abstract
The invention provides a method for extracting and recovering an organic solvent by using an ionic liquid. The method specifically comprises the following steps: extracting the mixed liquid containing the organic solvent and water by using the selected ionic liquid, rectifying the obtained extract phase, and further dehydrating the tower top product to finally obtain the organic solvent product with high purity and meeting the recycling requirement of the solvent. The ionic liquid has high selectivity to organic solvents and high extraction efficiency, and the finally obtained product of the organic solvents has the purity higher than 99.8 percent and the water content lower than 200ppm, and reaches the standard of recycling the organic solvents. The solvent and the process are green, the operation is simple and convenient, and the method is beneficial to industrial production.
Description
Technical Field
The invention relates to the field of chemical waste solvent treatment, in particular to a process for extracting, recovering, rectifying, dehydrating and refining an organic solvent in a recovered liquid by using an ionic liquid as a core extracting agent so as to finally obtain a high-purity organic solvent product.
Background
The organic solvent has various types and is widely used in chemical production, is an indispensable substance in modern production, not only can serve as a raw material for chemical reaction, but also can serve as a medium and a catalyst in the reaction process to promote the chemical reaction. A large amount of organic solvents are used in the coating industry, the pharmaceutical production industry, the fiber spinning industry and the like. The four solvents of methyl pyrrolidone, dimethyl sulfoxide, N-dimethylacetamide and N, N-dimethylformamide not only have good solubility to water, but also have good dissolving capacity to polymers, emulsions and the like, so that the solvent is widely used in polymerization spinning, drug synthesis and coating processing.
For example, in the spinning process, especially in the wet spinning process, N-dimethylformamide and N, N-dimethylacetamide are often used as a solvent in the polymerization production process of acrylon, polyvinyl chloride, aramid fiber and polyimide. And dimethyl sulfoxide is a cosolvent for preparing the carbon fiber. In the pharmaceutical industry, such as the pharmaceutical synthesis of iodoaminopyrimidine, doxycycline and cortisone, a large amount of the solvents are used as cosolvents in the process of synthesizing the medicine. In the paint industry, these four types of solvents with better solvency are also often used in order to better dissolve the polymeric components of the paint. In the above process, a large amount of organic solvent to be recovered is generated. If the high-value non-protonized organic solvent cannot be effectively recycled and reused, a large amount of solvent resources are wasted, the production cost of enterprises is increased, and certain harm is brought to the environment. Therefore, the research on the recovery method is of great theoretical and practical significance.
At present, there are three main methods for treating the recovered organic solvent, among which, although the distillation-rectification technique is technically feasible, such as the reported patent document CN 101462977B, CN 102030672A, CN 102225904B, CN 103936646B, CN 207210299U, the energy consumption is huge, and especially when treating the recovered liquid system of low-concentration organic solvent, the problem of energy consumption is especially outstanding. However, the membrane separation technology has a good concentration effect on such organic solvents, such as patent documents CN 102992502A and CN 102993039 a, but has high requirements on the raw materials to be processed, and cannot contain salts and impurities, so that the applicability is greatly limited. Another recovery technique that has been studied more is the extraction-rectification technique. The organic solvent in the recovered liquid is first enriched in the extracting agent by extraction, the solvent water with large vaporization enthalpy is replaced by other organic solvent, and then the organic solvent and the extracting agent are recovered by rectification technology, such as patent documents CN101255122 a, CN 105646271A, CN 105645501A, CN 1317259C, etc.
The core problem of the extraction-rectification technique compared to other processes is the choice of extractant, which will have a severe impact on the separation efficiency and the quality of the product. Chlorine-containing compounds are now being studied more frequently as extractants, for example in patent documents CN 101255122A, CN105646271 a and CN105645501 a.
Generally, the extraction efficiency of the used extracting agent is not high, so that the whole process flow is complicated, and some extracting agents have certain environmental protection problems and are not suitable for industrial use. Therefore, in order to solve the above problems, it is necessary to develop a new recovery process for the recovered organic solvent. In particular, the high efficiency of the extractant is very important and is the meaning of the invention.
Disclosure of Invention
The invention provides a method for extracting and recovering an organic solvent by using an ionic liquid, and an operation method of the organic solvent which is obtained by using the process method, has high purity and can meet the requirement of production and application. The method has the advantages of high selectivity of the extraction process, simple process flow, low energy consumption, environment-friendly process and renewable utilization due to the adoption of the green ionic liquid solvent, and is beneficial to industrial production.
The object of the invention can be achieved by the following measures:
the technical scheme of the invention comprises the following steps: extracting the mixed liquid containing the organic solvent and the water by using ionic liquid, and rectifying the obtained extract phase.
In the invention, the ionic liquid is used for extracting and recovering the organic solvent, and the anion of the ionic liquid comprises tetrafluoroborate anion BF4 -Hexafluorophosphate radical anion PF6 -Bis (trifluoromethanesulfonylimide) anion NTF2 -Or the tris (pentafluoroethyl) trifluorophosphate anion eFAP-(ii) a The cation of the ionic liquid comprises a 2-substituted alkyl imidazole cation shown as a formula 1:
wherein R is1Is C2～C10Linear alkyl group of (1). Preferably C4～C8The straight-chain alkane of (1) includes butyl, pentyl, hexyl, heptyl and octyl, more preferably C6～C8The straight-chain alkane comprises hexyl, heptyl and octyl. Because the ionic liquid is a hydrophobic high-boiling-point solvent and is kept in the tower kettle in the rectification process, only a small amount of products and entrained water need to be removed from the tower top, and the energy consumption is greatly reduced.
In the invention, the organic solvent in the mixed solution containing the organic solvent and water is at least one of N, N-dimethylacetamide, N-dimethylformamide, methylpyrrolidone and dimethyl sulfoxide. The mixed liquid comprises process water and wastewater. The process water is a recovery liquid containing an organic solvent in a process, and the wastewater comprises wastewater generated in a synthetic processing process, a polymerization spinning process, a medicine process and a coating production process, but is not limited to the wastewater generated in the industries. In the present invention, the content of the organic solvent is 3 to 50 wt%, preferably 3 to 30 wt%, and more preferably 5 to 20 wt%. Within the content range, the using effect of the process method is better.
In the invention, the extraction is carried out in a multi-stage countercurrent extraction mode; the extraction is carried out by adopting extraction equipment comprising an extraction clarifying tank or a series of multi-stage centrifugal extractors.
In the present invention, the number of stages of the multi-stage countercurrent extraction is 3 to 8, preferably 5 to 8, and more preferably 6 to 8.
In the present invention, the operation temperature of the multi-stage countercurrent extraction is 25 to 55 ℃, preferably 25 to 45 ℃, and most preferably 25 to 35 ℃. Within the temperature range, the ionic liquid has better extraction effect, and does not need to provide a large amount of heat from the outside.
In the present invention, the amount of the ionic liquid used is 0.5 to 10 times, preferably 2 to 10 times, and more preferably 4 to 8 times the amount of the mixed solution containing the organic solvent and water to be treated. The dosage of the extractant is in the range, the extraction effect is improved to a certain extent, particularly the concentration of the organic solvent in the treated water phase can be reduced, and the recovery rate is improved.
In the invention, the extraction phase is an ionic liquid phase in the last stage of multistage countercurrent extraction, and the phase contains extracted organic solvent and a small amount of water dissolved in ionic liquid besides the ionic liquid extractant.
In the present invention, the operating pressure of the rectification operation is 0.25atm to 1atm, preferably 0.5atm to 1atm, more preferably 0.5atm to 0.75 atm; the reflux ratio of the operation is 0.3 to 2, preferably 0.3 to 1, and more preferably 0.5 to 1. Controlling the operation temperature at the top of the tower, and collecting corresponding fractions. Wherein the operation temperature of the N, N-dimethylacetamide is controlled to be 143-166 ℃, the operation temperature of the N, N-dimethylformamide is controlled to be 107-152 ℃, the operation temperature of the methylpyrrolidone is controlled to be 154-204 ℃, and the operation temperature of the dimethyl sulfoxide is controlled to be 143-191 ℃.
In the invention, the method also comprises a dehydration step, and the further dehydration is carried out in a dehydration tower. The water content of the crude product in the organic solvent collected from the top of the rectifying tower is higher, generally more than 2000ppm, which can not meet the requirement, and a further dehydration link needs to be added to reduce the water content to below 200 ppm. The dehydration is carried out in a dehydration tower filled with molecular sieves, which enters from the lower part of the dehydration tower and obtains the organic solvent product from the upper part of the dehydration tower.
The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows: the invention provides a method for extracting and recovering an organic solvent by using an ionic liquid. Compared with other reported extracting agents, the ionic liquid extracting agent used in the method has the advantages of good selectivity, high extraction efficiency, green used solvent and solvent, low energy consumption, high purity of the obtained organic solvent, high recovery rate and capability of completely meeting the requirement of recycling the solvent.
Drawings
FIG. 1: a process flow chart of the ionic liquid extraction and recovery of the organic solvent. Wherein A is represented by an extraction unit, B is represented by a rectification column, and C is represented by a dehydration column. 1 is a mixed liquid containing an organic solvent and water, 2 is an ionic liquid extractant, 3 is a raffinate phase after multi-stage extraction, 4 is an extract phase after multi-stage extraction, 5 is a tower top product of a rectifying tower, 6 is a tower bottom product of the rectifying tower, and 7 is a product of a dehydrating tower.
Mixed liquid containing organic solvent and water and ionic liquid extractant respectively enter from two ends of an extraction unit, and after multi-stage extraction, an extraction phase and a raffinate phase are respectively obtained, wherein the raffinate phase enters a wastewater treatment system for next-step treatment, the extraction phase enters a rectifying tower, the extractant is obtained at a tower kettle and can be repeatedly used to enter the extraction unit, a tower top product is organic solvent and a small amount of water, the organic solvent and the small amount of water enter a dehydrating tower for further treatment, and finally an organic solvent product is obtained at the upper end of the dehydrating tower.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
Example 1
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 3 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 3-stage countercurrent extraction at 35 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 1, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.88%, the water content is 112ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.4%.
Example 2
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 5 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as the extractant, and the extractant flow rate was set to 80 ml/min. Performing 5-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.5atm with reflux ratio of 0.5, controlling overhead temperature at 141 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.91%, the water content is 126ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 99.2%.
Example 3
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 20 ml/min. Performing 6-stage countercurrent extraction at 45 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.25atm with reflux ratio of 0.3, controlling overhead temperature at 120 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.89%, the water content is 133ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.5%.
Example 4
A certain amount of 30 percent N, N-dimethylacetamide mixed solution with the treatment flow of 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) as an extractant, and the flow rate of the extractant is set to 10 ml/min. Performing 8-stage countercurrent extraction at 55 deg.C to obtain extract phase, rectifying the obtained extract phase at 1atm with reflux ratio of 2, controlling the temperature at the top of the column to 166 deg.C, and collecting corresponding fraction. Finally, the rectification obtained isAnd dehydrating the tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.93%, the water content is 98ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.6%.
Example 5
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 50 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 160 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 1.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.90%, the water content is 121ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.4%.
Example 6
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 10 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set at 200 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.94%, the water content is 101ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 99.0%.
Example 7
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.3, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.90%, the water content is 118ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.9%.
Example 8
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.92%, the water content is 125ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.8%.
Example 9
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-Ethyl-3-methylimidazolium hexafluorophosphate ([ C ] is used2MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. The analysis shows that the purity of the N, N-dimethylacetamide is 99.83 percent, the water content is 152ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamideThe content was 97.6%.
Example 10
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-propyl-3-methylimidazolium hexafluorophosphate ([ C ] is used3MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.85%, the water content is 150ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 97.8%.
Example 11
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-butyl-3-methylimidazolium hexafluorophosphate ([ C ] is used4MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.84%, the water content is 143ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 97.8%.
Example 12
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-pentyl-3-methylimidazolium hexafluorophosphate ([ C ] is used5MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. Finally, will obtainAnd dehydrating the tower top fraction of the rectifying tower through a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.89%, the water content is 139ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.4%.
Example 13
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-hexyl-3-methylimidazolium hexafluorophosphate ([ C ] is used6MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.91%, the water content is 140ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.5%.
Example 14
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. Use of 1-heptyl-3-methylimidazolium hexafluorophosphate ([ C ]7MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.92%, the water content is 127ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.6%.
Example 15
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-octyl-3-methylimidazolium hexafluorophosphate ([ C ] is used8MIm]Pf6) For extraction ofThe flow rate of the extractant and the extraction agent is set to be 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.92%, the water content is 129ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 98.8%.
Example 16
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-nonyl-3-methylimidazolium hexafluorophosphate ([ C ] is used9MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.93%, the water content is 118ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 99.0%.
Example 17
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-decyl-3-methylimidazolium hexafluorophosphate ([ C ] is used10MIm]Pf6) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.93%, the water content is 126ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 99.2%.
Example 18
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-hexyl-3-methylimidazolium tetrafluoroborate ([ C ]) was used6MIm]Bf4) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.82%, the water content is 192ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 97.5%.
Example 19
A certain amount of N, N-dimethylacetamide mixed solution with the concentration of 20 percent, and the treatment flow is 20 ml/min. 1-hexyl-3-methylimidazolium bistrifluoromethanesulfonylimide salt ([ C)6MIm]NTf2) As an extractant, the flow rate of the extractant was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 156 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. According to analysis, the purity of the N, N-dimethylacetamide is 99.84%, the water content is 172ppm, the requirement of solvent application is met, and the overall recovery rate of the N, N-dimethylacetamide is 97.9%.
Example 20
A certain amount of N, N-dimethylformamide mixed solution with the concentration of 20 percent, and the treatment flow rate is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 141 deg.C, and collecting corresponding fraction. Finally, will obtainThe distillation tower top fraction is dehydrated by a dehydrating tower to obtain a high-purity N, N-dimethylacetamide product. Through analysis, the purity of the N, N-dimethylformamide is 99.91%, the water content is 131ppm, the requirement of solvent recycling is met, and the overall recovery rate of the N, N-dimethylformamide is 98.6%.
Example 21
A certain amount of dimethyl sulfoxide mixed solution with the concentration of 20 percent, and the treatment flow rate is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling the temperature at the top of the column to 180 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity dimethyl sulfoxide product. Through analysis, the purity of the dimethyl sulfoxide is 99.83%, the water content is 152ppm, the requirement of solvent recycling is met, and the overall recovery rate of the dimethyl sulfoxide is 97.8%.
Example 22
A certain amount of mixed solution of methyl pyrrolidone with the concentration of 20 percent, and the treatment flow rate is 20 ml/min. 1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate ([ C ] was used4MIm]eFAP) was used as extractant, and the extractant flow rate was set to 40 ml/min. Performing 6-stage countercurrent extraction at 25 deg.C to obtain extract phase, rectifying the obtained extract phase at 0.75atm with reflux ratio of 0.5, controlling overhead temperature at 193 deg.C, and collecting corresponding fraction. And finally, dehydrating the obtained distillation tower top fraction by a dehydrating tower to obtain a high-purity methyl pyrrolidone product. Through analysis, the purity of the methyl pyrrolidone is 99.96%, the water content is 120ppm, the requirement of solvent application is met, and the overall recovery rate of the methyl pyrrolidone is 99.3%.
In the present invention, the purity of the product of all examples was measured by HPLC, and the moisture content was measured by a moisture analyzer.
It should be understood that after reading the above description of the present invention, various changes or modifications can be made by those skilled in the art to the relevant conditions of the present invention, and these equivalents also fall within the scope of the appended claims of the present application.
Claims (10)
1. A method for extracting and recovering an organic solvent by using an ionic liquid is characterized in that a mixed solution containing the organic solvent and water is extracted by using the ionic liquid, and an obtained extract phase is rectified.
2. The process for the extractive recovery of an organic solvent according to claim 1, wherein the anion of the ionic liquid comprises the tetrafluoroborate anion, BF4 -Hexafluorophosphate radical anion PF6 -Bis (trifluoromethanesulfonylimide) anion NTF2 -Or the tris (pentafluoroethyl) trifluorophosphate anion eFAP-(ii) a The cation of the ionic liquid comprises a 2-substituted alkyl imidazole cation shown as a formula 1:
wherein R is1Is C2～C10Linear alkyl group of (1).
3. The method for extracting and recovering an organic solvent by using an ionic liquid as claimed in claim 1, wherein the organic solvent in the mixed solution containing the organic solvent and water comprises at least one of N, N-dimethylacetamide, N-dimethylformamide, methylpyrrolidone and dimethylsulfoxide.
4. The method for extracting and recovering an organic solvent according to claim 1, wherein the content of the organic solvent in the mixed solution containing the organic solvent and water is 3 to 50 wt%.
5. The method for extracting and recovering the organic solvent by the ionic liquid as claimed in claim 1, wherein the extraction is carried out by adopting a multi-stage countercurrent extraction mode; the extraction is carried out by adopting extraction equipment comprising an extraction clarifying tank or a series of multi-stage centrifugal extractors.
6. The method for extracting and recovering the organic solvent by using the ionic liquid as claimed in claim 5, wherein the number of stages of the multistage countercurrent extraction is 3-8.
7. The method for extracting and recovering organic solvent from ionic liquid as claimed in claim 5, wherein the operation temperature of the multi-stage countercurrent extraction is 25-55 ℃.
8. The method for extracting and recovering an organic solvent according to claim 1, wherein the amount of the ionic liquid used is 0.5 to 10 times the amount of the mixed solution containing the organic solvent and water.
9. The method for the extractive recovery of an organic solvent according to claim 1, wherein the rectification operation is performed at an operating pressure of 0.25atm to 1 atm; the reflux ratio of the operation is 0.3-2; controlling the operation temperature at the top of the tower, and collecting corresponding fractions.
10. The method for the extractive recovery of an organic solvent according to claim 1, further comprising a dehydration step, preferably in a dehydration column.
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