CN109867622B

CN109867622B - Method for preparing ionic liquid and device for preparing ionic liquid

Info

Publication number: CN109867622B
Application number: CN201711252445.9A
Authority: CN
Inventors: 余磊; 金学平; 张毅; 徐超
Original assignee: WUHAN VOCATIONAL COLLEGE OF SOFTWARE AND ENGINEERING
Current assignee: WUHAN VOCATIONAL COLLEGE OF SOFTWARE AND ENGINEERING
Priority date: 2017-12-01
Filing date: 2017-12-01
Publication date: 2023-05-05
Anticipated expiration: 2037-12-01
Also published as: CN109867622A

Abstract

The invention provides a method for preparing an ionic liquid and a device for preparing the ionic liquid. Wherein the method comprises the following steps: the cation donor and the anion donor are subjected to heterogeneous countercurrent contact so as to obtain an ionic liquid. The inventor finds that the ionic liquid is prepared by adopting the heterogeneous countercurrent contact method, and different phases in countercurrent contact carry out countercurrent mass transfer and heat transfer in the reaction process, so that reactants in different phases can react more fully when in contact, the yield of the obtained ionic liquid is higher, the method is flexible and convenient to operate, mild in condition, suitable for large-scale continuous stable production, and low in production cost.

Description

Method for preparing ionic liquid and device for preparing ionic liquid

Technical Field

The invention relates to the field of chemistry, in particular to a method for preparing ionic liquid and a device for preparing ionic liquid.

Background

The ionic liquid is a salt which is liquid at room temperature or near room temperature and is completely composed of anions and cations, also called as low-temperature molten salt, and has the characteristics of non-volatility, incombustibility, strong conductivity, large heat capacity, small vapor pressure, stable property, good solubility for a plurality of inorganic salts and organic matters, and the like, so the ionic liquid is widely applied to the fields of electrochemistry, organic synthesis, catalysis, separation and the like.

Ionic liquids when compared to traditional organic solvents or electrolytes, ionic liquids have a series of outstanding advantages: (1) The liquid range is wide, and the heat stability and the chemical stability are high from below or near room temperature to above 300 ℃; (2) The vapor pressure is very small, the volatile organic compound is not volatilized, can not evaporate and lose in use and storage, can be recycled, eliminates the environmental pollution problem of the volatile organic compound, has high conductivity and large electrochemical window, and can be used as electrolyte for electrochemical research of a plurality of substances; (4) The solubility of the organic acid-inorganic compound to inorganic matters, water, organic matters and polymers can be regulated by designing anions and cations, and the acidity of the organic acid-inorganic compound can be regulated to super acid. (5) Has high polarity controllability, low viscosity and high density, can form a two-phase or multi-phase system, and is suitable forAs separating solvent or forming new reaction-separation coupling system; (6) The catalyst has good dissolving capacity to a large amount of inorganic and organic substances, has dual functions of a solvent and a catalyst, and can be used as a solvent or a catalytic active carrier for a plurality of chemical reactions. Because of these particular properties and behavior of ionic liquids, it is believed to be compatible with supercritical CO ₂ And the three green solvents are formed together with the aqueous two phase, so that the aqueous two-phase aqueous three-phase solvent has wide application prospect.

However, at present, the preparation of ionic liquids, particularly the preparation of high-purity ionic liquids, is generally still in a laboratory stage, and the industrial production process is still immature. In production, a large amount of waste acid, waste gas or heavy metal salt is generated, which poses a threat to the environment. The preparation of the high-purity (halogen-free) ionic liquid generally uses special ion exchange resin, and the regeneration cost of the special ion resin is very high, so that the industrial process of the ionic liquid is restricted.

Thus, the current process for preparing ionic liquids remains to be improved.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a method for preparing an ionic liquid which can prepare an ionic liquid of high purity, has a high yield of the ionic liquid, or is simple and convenient to operate.

In one aspect of the invention, a method of preparing an ionic liquid is provided. According to an embodiment of the invention, the method comprises: the cation donor and the anion donor are subjected to heterogeneous countercurrent contact so as to obtain an ionic liquid. The inventor finds that the ionic liquid is prepared by adopting the heterogeneous countercurrent contact method, and different phases in countercurrent contact carry out countercurrent mass transfer and heat transfer in the reaction process, so that reactants in different phases can react more fully when in contact, the yield of the obtained ionic liquid is higher, the method is flexible and convenient to operate, mild in condition, suitable for large-scale continuous stable production, and low in production cost.

According to an embodiment of the invention, the cation donor is selected from the group consisting of N-methylimidazole, pyridine, 1-butyl-3-methylimidazole halide, butylpyridine halide, 1-butyl-3-methylimidazole hexafluorophosphate and butylpyridine hexafluorophosphate; the anion donor is selected from the group consisting of haloalkanes, hexafluorophosphates and tetrafluoroborates. Therefore, the ionic liquid obtained by the reaction of the cation donor and the anion donor has stable property, wide application and better use performance.

According to an embodiment of the invention, the 1-butyl-3-methylimidazole halogen salt is 1-butyl-3-methylimidazole chloride salt, and the butylpyridine halogen salt is butylpyridine chloride salt; the haloalkane is chlorobutane. Therefore, the ionic liquid obtained by the reaction of the cation donor and the anion donor has stable property, wide application and better use performance.

According to an embodiment of the invention, the heterogeneous countercurrent contacting is performed in a rectifying column or an extracting column. Therefore, the rectifying tower or the extraction tower device can provide a good environment for the heterogeneous countercurrent contact so as to facilitate the heterogeneous countercurrent reaction, and the device has wide sources, simple and convenient operation and better usability and is suitable for industrial application.

According to an embodiment of the invention, the method comprises: in the rectifying column, N-methylimidazole or pyridine is subjected to the out-of-phase countercurrent contact with the haloalkane so as to obtain the 1-butyl-3-methylimidazole halide salt or the butylpyridine halide salt. Therefore, in the rectifying tower, N-methylimidazole or pyridine is a descending liquid phase, and halogenated alkane is an ascending gas phase to carry out heterogeneous countercurrent contact, so that the mass and heat transfer driving force is large, the mass and heat transfer effect is good, and the yield of the 1-butyl-3-methylimidazole halogen salt or butyl pyridine halogen salt is high.

According to an embodiment of the invention, the method further comprises: in the extraction column, the 1-butyl-3-methylimidazole halogen salt or the butylpyridine halogen salt is subjected to the out-of-phase countercurrent contact with the hexafluorophosphate or the tetrafluoroborate to obtain 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, butylpyridine hexafluorophosphate or butylpyridine tetrafluoroborate. Thus, in the extraction tower, 1-butyl-3-methylimidazole halogen salt or butyl pyridine halogen salt is dissolved in an organic solvent to form a continuously-descending oil phase (or heavy phase), hexafluorophosphate or tetrafluoroborate is dissolved in water to form a continuously-ascending water phase (or light phase) for heterogeneous countercurrent contact, the mass and heat transfer driving force is larger, the mass and heat transfer effects are better, the yield of 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, butyl pyridine hexafluorophosphate or butyl pyridine tetrafluoroborate is higher, and the product does not contain halogen and has higher purity.

According to an embodiment of the invention, the method further comprises: reacting said 1-butyl-3-methylimidazolium hexafluorophosphate or said butylpyridinium hexafluorophosphate with said tetrafluoroborate to obtain said 1-butyl-3-methylimidazolium tetrafluoroborate or said butylpyridinium tetrafluoroborate. Therefore, the method is simple and convenient to operate and easy to realize, the yield of the 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate is high, and the product does not contain halogen and has high purity.

In another aspect of the invention, the invention provides an apparatus for preparing the ionic liquid as described above. According to an embodiment of the invention, the apparatus comprises: the rectifying tower, rectifying tower top is provided with first cation donor entry, and the bottom is provided with first anion donor entry and first product export. The inventor finds that the rectifying tower device has wide sources, can prepare the ionic liquid by the heterogeneous countercurrent contact method in the rectifying tower, has simple and convenient operation and is beneficial to realizing large-scale production.

According to an embodiment of the invention, the apparatus further comprises: the extraction tower, the extraction tower top be provided with the second cation donor entry that is linked together with first product export, the bottom is provided with second anion donor entry and second product export. Therefore, the extraction tower device has wide sources, can be used for preparing the ionic liquid by the heterogeneous countercurrent contact method in the extraction tower, is simple and convenient to operate, can realize continuous production by connecting the extraction tower with the rectifying tower, and is beneficial to realizing large-scale production.

According to an embodiment of the invention, the apparatus further comprises: a reactor provided with a third cation donor inlet, a third anion donor inlet, and a third product outlet, wherein the third cation donor inlet is in communication with the second product outlet. Therefore, the ionic liquid preparation method has the advantages that the variety of the reactors is more, the sources are wider, the operation of preparing the ionic liquid in the reactors is simple and convenient, and the continuous production can be realized by connecting the reactors with the extraction tower, so that the large-scale production can be realized.

According to an embodiment of the invention, the apparatus further comprises: the first anion donor recovery assembly is provided with a first material inlet and a first material outlet which are communicated with the rectifying tower; a first product purification assembly provided with a fourth material inlet in communication with the first product outlet, a sixth material outlet in communication with the first anion donor inlet, and a seventh material outlet in communication with the second cation donor inlet; a second product purification assembly provided with a second material inlet in communication with the second product outlet, a second material outlet in communication with the extraction column, and a third material outlet in communication with the third cation donor inlet; and the third product purification assembly is provided with a third material inlet communicated with the third product outlet, a fourth material outlet communicated with the extraction tower and a fifth material outlet. Therefore, the first anion donor recovery component, the first product purification component, the second product purification component and the third product purification component are arranged in the device, so that the recovery and reutilization or purification of each product are realized, the reaction and purification can be changed into a linked production line, the control point of key quality in production can be conveniently determined, the purity of the obtained ionic liquid is higher, the subsequent application of the ionic liquid is convenient, the cost is saved, the continuous or large-scale production is facilitated, and the device is suitable for industrial application.

Drawings

Fig. 1 is a schematic view of an apparatus for preparing an ionic liquid in one embodiment of the present invention.

Fig. 2 is a schematic view of an apparatus for preparing an ionic liquid according to another embodiment of the present invention.

Fig. 3 is a schematic view of an apparatus for preparing an ionic liquid according to another embodiment of the present invention.

Fig. 4 is a schematic view of an apparatus for preparing an ionic liquid according to another embodiment of the present invention.

Fig. 5 is a schematic view of an apparatus for preparing an ionic liquid in another embodiment of the present invention.

Detailed Description

Embodiments of the present invention are described in detail below. The following examples are illustrative only and are not to be construed as limiting the invention. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

The present invention has been completed based on the following findings and findings of the inventors:

currently, ionic liquids (particularly quaternary ammonium salt ionic liquids) are generally prepared by a two-step process, wherein in a first reaction step, halide salts containing target cations are prepared by a quaternization reaction; then the target anion donor is used for replacing halogen ions or Lewis acid is added to obtain the target ionic liquid. In the second reaction step, the metal salt MY (M represents a metal cation, Y represents a target anion, commonly AgY), HY or NH is used ₄ During Y, ag salt precipitate or amine salt and HX gas are easily removed, then strong protonic acid HY is added, the reaction is required to be carried out under the condition of low-temperature stirring, then the reaction is repeatedly washed to be neutral, the ionic liquid is extracted by using an organic solvent, and finally the organic solvent is removed in vacuum to obtain the pure ionic liquid. The synthesis of high purity binary ionic liquids is typically prepared by anion exchange in an ion exchanger using ion exchange resins. In the preparation process, a large amount of waste acid, waste gas or heavy metal salt is generated, which causes threat to the environment; the preparation of the high-purity (halogen-free) ionic liquid generally uses special ion exchange resin, and the regeneration cost of the special ion resin is very high, so that the industrial process of the ionic liquid is restricted. The inventors have conducted intensive studies to solve the above-mentioned problems, and found that an ionic liquid can be produced by a heterogeneous countercurrent contact methodThe method ensures that reactants in different phases are contacted more fully in the reaction process, has better countercurrent mass and heat transfer effect and larger pushing force, ensures that the obtained ionic liquid has higher purity, greatly reduces the production of waste acid, waste gas or heavy metal salt, is environment-friendly, can realize large-scale industrial production, has simple device, flexible and convenient operation and mild condition, does not need special ion exchange resin or equipment, has low production cost, can simultaneously produce various ionic liquids, and is favorable for continuous production.

In view of this, in one aspect of the invention, the invention provides a method of preparing an ionic liquid. According to an embodiment of the invention, the method comprises: the cation donor and the anion donor are subjected to heterogeneous countercurrent contact so as to obtain an ionic liquid. The inventor finds that the ionic liquid is prepared by adopting the heterogeneous countercurrent contact method, and different phases in countercurrent contact carry out countercurrent mass transfer and heat transfer in the reaction process, so that reactants in different phases can react more fully when in contact, the yield of the obtained ionic liquid is higher, the method is flexible and convenient to operate, mild in condition, suitable for large-scale continuous stable production, and low in production cost.

According to the embodiments of the present invention, the kind of the cation donor is not particularly limited as long as the cation can be effectively provided, and one skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the cation donor is selected from the group consisting of N-methylimidazole, pyridine, 1-butyl-3-methylimidazole halide, butylpyridine halide, 1-butyl-3-methylimidazole hexafluorophosphate, and butylpyridine hexafluorophosphate. According to the embodiments of the present invention, the kind of the anion donor is not particularly limited as long as the anion can be effectively provided, and one skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the anion donor is selected from the group consisting of haloalkanes, hexafluorophosphates, and tetrafluoroborates. In some embodiments of the invention, the haloalkane is chlorobutane or bromobutane, preferably chlorobutane, the hexafluorophosphate is potassium hexafluorophosphate or sodium hexafluorophosphate, and the tetrafluoroborate is potassium tetrafluoroborate or sodium tetrafluoroborate. Therefore, the ionic liquid obtained by the reaction of the cation donor and the anion donor has stable property, wide application and better use performance.

The specific kind of 1-butyl-3-methylimidazole halogen salt according to the examples of the present invention is not particularly limited as long as it can meet the requirements, and one skilled in the art can flexibly select it according to actual needs. In some embodiments of the invention, the 1-butyl-3-methylimidazole halogen salt is 1-butyl-3-methylimidazole chloride salt or 1-butyl-3-methylimidazole bromide salt, preferably 1-butyl-3-methylimidazole chloride salt, thereby being less costly. The specific kind of butylpyridinium halide salt according to the embodiments of the present invention is not particularly limited as long as it can meet the requirements, and those skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the butylpyridinium halide salt is butylpyridinium chloride salt or butylpyridinium bromide salt, preferably butylpyridinium chloride salt. Therefore, the ionic liquid obtained by adopting the reaction of the cation donor and the anion donor has the advantages of stable property, wide application, better use performance and lower cost.

It should be noted that heterogeneous refers to different phases, which may be an aqueous phase and an oil phase, may be a gas phase and a liquid phase, or may be other possible different phases.

According to the embodiments of the present invention, the way of heterogeneous countercurrent contact is not particularly limited, and those skilled in the art can flexibly select according to actual needs as long as the requirements for effectively improving mass transfer or heat transfer can be satisfied. For example, it may involve the countercurrent contact of the ascending gas phase with the descending liquid phase, or the countercurrent contact of the ascending water phase with the descending oil phase.

According to the embodiments of the present invention, the reaction apparatus for the heterogeneous countercurrent contact is not particularly limited as long as the conditions for the heterogeneous countercurrent contact can be provided, and those skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the out-of-phase countercurrent contacting is performed in a rectification column or an extraction column. Therefore, the rectifying tower or the extraction tower device can provide a good environment for the heterogeneous countercurrent contact so as to facilitate the heterogeneous countercurrent reaction, and the device has wide sources, simple and convenient operation and better use performance.

According to the embodiment of the invention, the type of the rectifying tower is not particularly limited, and a person skilled in the art can flexibly select the rectifying tower according to actual needs as long as the rectifying tower can meet the requirements, for example, the rectifying tower can be a plate tower or a packed tower, wherein the packing in the packed tower can be a glass spring, a wire mesh, a stainless steel raschig ring or a metal pall ring, and the like. Therefore, the device has wide sources and convenient operation, and is suitable for industrial application; and the heterogeneous phase in the rectifying tower can be gas phase and liquid phase, and the operating condition of the rectifying tower can be total reflux, so that the gas-liquid two-phase contact is more sufficient, the reaction is more complete, and the yield of the product is improved.

According to an embodiment of the invention, in the rectifying column, N-methylimidazole or pyridine is subjected to the out-of-phase countercurrent contact with the haloalkane, so as to obtain the 1-butyl-3-methylimidazole halide salt or the butylpyridine halide salt (labeled as product 1). Therefore, in the rectifying tower, N-methylimidazole or pyridine is a descending liquid phase, and halogenated alkane is an ascending gas phase to carry out heterogeneous countercurrent contact, so that the mass and heat transfer driving force is large, the mass and heat transfer effect is good, and the yield of the 1-butyl-3-methylimidazole halogen salt or butyl pyridine halogen salt is high.

According to the embodiments of the present invention, the heterogeneous countercurrent contact reaction occurring in the rectifying tower is specifically described by taking N-methylimidazole or pyridine and chlorobutane as raw materials to synthesize 1-butyl-3-methylimidazole chloride or butylpyridine chloride as examples, and it should be noted that the examples described below are illustrative only and are not to be construed as limiting the present invention. The reaction equation of N methylimidazole or pyridine and chlorobutane is:

in the rectifying tower, chlorobutane is an ascending gas phase, N-methylimidazole or pyridine is a descending liquid phase, and the gas phase and the liquid phase are fully contacted by utilizing the internal structure (tower plates or filling materials) of the rectifying tower to generate chemical reaction so as to generate nonvolatile ionic compound 1-butyl-3-methylimidazole chloride or butylpyridine chloride. Specifically, chlorobutane is fed from the tower kettle, heated into gas phase, and ascended in the tower to the top of the tower to be subjected to total reflux through a condenser. The liquid phase of N-methylimidazole or pyridine is fed from the top of the column and flows downwards in the column. In the tower, as ascending gas-phase chlorobutane and descending liquid-phase N-methylimidazole or pyridine continuously make heterogeneous countercurrent contact, the reaction is carried out to consume, the generated product 1-butyl-3-methylimidazole chloride or butylpyridine chloride is in a liquid state, and continuously descends, is finally enriched in the tower kettle, is extracted after being cooled, and can also be used as a first intermediate to enter the next process. It should be noted that during the feed, it is necessary to ensure an excess of chlorobutane, which is recovered at the top of the column when the column bottom effluent is detected as being free of N methylimidazole or pyridine.

According to the embodiment of the present invention, when the reaction is performed in the rectifying column, reaction parameters (e.g., reaction temperature, raw material feed flow rate, etc.) are not particularly limited, and may be flexibly selected according to actual needs by those skilled in the art as long as the reaction is enabled to be performed more completely.

According to the embodiment of the invention, the types of the extraction tower are not particularly limited, and can be flexibly selected according to actual needs by a person skilled in the art as long as the requirements can be met, for example, the types of the extraction tower can be a rotary disk extraction tower, a pulse extraction tower or a vibrating plate extraction tower, and the like, so that the extraction tower has wide sources, is simple to operate and has good usability.

According to the embodiment of the invention, the heterogeneous phase in the extraction tower can be an oil phase and a water phase, and the countercurrent contact of the oil phase and the water phase in the extraction tower can enable the reaction to be more sufficient, so that the yield of the product is improved.

According to an embodiment of the present invention, said 1-butyl-3-methylimidazole halogen salt or said butylpyridine halogen salt is subjected to said out-of-phase countercurrent contact with said hexafluorophosphate or said tetrafluoroborate in said extraction column so as to obtain 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, butylpyridine hexafluorophosphate or butylpyridine tetrafluoroborate (labeled as product 2) as product 1 proceeds to the next process to participate in the reaction. Thus, in the extraction tower, 1-butyl-3-methylimidazole halogen salt or butyl pyridine halogen salt is dissolved in an organic solvent to form a continuously-descending oil phase (or heavy phase), hexafluorophosphate or tetrafluoroborate is dissolved in water to form a continuously-ascending water phase (or light phase) for heterogeneous countercurrent contact, the mass and heat transfer driving force is larger, the mass and heat transfer effect is better, the yield of 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, butyl pyridine hexafluorophosphate or butyl pyridine tetrafluoroborate is higher, and no halogen exists in the product, and the purity is higher.

According to the embodiments of the present invention, the heterogeneous countercurrent contact reaction occurring in the extraction column is specifically described using 1-butyl-3-methylimidazole chloride or butylpyridinium chloride and potassium hexafluorophosphate as raw materials, and it should be noted that the examples described below are illustrative only and are not to be construed as limiting the present invention. The reaction equation of 1-butyl-3-methylimidazole chloride or butylpyridinium chloride and potassium hexafluorophosphate is:

in the extraction column, potassium hexafluorophosphate is dissolved in water to form a light phase, which is fed from the bottom of the extraction column, and 1-butyl-3-methylimidazole chloride or butylpyridine chloride is dissolved in chloroform to form a heavy phase, which is fed from the top of the extraction column. In the extraction tower, the water phase (or light phase) continuously rises, the oil phase (or heavy phase) continuously falls, heterogeneous countercurrent contact is carried out, reaction is carried out, the generated product KCl is enriched in water, and the generated product 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate is oily substance and is enriched in chloroform. By tracking the reaction during the reaction, detecting the absence of organic ions in the aqueous phase, the reaction is considered complete. The aqueous phase flowing out of the tower top is evaporated and concentrated to collect KCl, the mixture of 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate and chloroform flowing out of the tower bottom is separated and purified by a first distillation tower, the recovered chloroform is recycled, and the 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate can be extracted after being cooled in the first distillation tower kettle or can be used as a second intermediate to enter the next process.

According to the embodiment of the invention, the operation conditions of the extraction tower and the first distillation tower are not particularly limited, so long as the requirements can be met, the technical personnel can flexibly select according to actual needs, the feeding flow rate of materials in the extraction tower and the first distillation tower and the like are also not particularly limited, so long as the reaction or purification can be more complete, and the technical personnel can flexibly select according to the actual needs.

According to an embodiment of the invention, when the product 2 continues to participate in the reaction, the method further comprises: reacting said 1-butyl-3-methylimidazolium hexafluorophosphate or said butylpyridinium hexafluorophosphate with said tetrafluoroborate to obtain said 1-butyl-3-methylimidazolium tetrafluoroborate or said butylpyridinium tetrafluoroborate (labeled as product 3). Therefore, the method is simple and convenient to operate and easy to realize, and the yield of the 1-butyl-3-methylimidazole tetrafluoroborate or the butylpyridine tetrafluoroborate is higher, and the product has no halogen and has higher purity.

According to the embodiments of the present invention, the apparatus for reacting 1-butyl-3-methylimidazolium phosphate or butylpyridinium hexafluorophosphate with tetrafluoroborate is not particularly limited as long as it can meet the requirements, and those skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the reaction device is a full back-mixing kettle type reactor or a third extraction tower, so that the reaction device has wide sources, is simple to operate, and can obtain a higher yield of the product.

According to the embodiment of the invention, if the reactor is a full back-mixing kettle type reactor, the 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate and tetrafluoroborate are subjected to full back-mixing reaction; if the reactor is a third extraction tower, the 1-butyl-3-methylimidazolium hexafluorophosphate or butylpyridinium hexafluorophosphate and tetrafluoroborate undergo heterogeneous countercurrent contact reaction, specifically, the 1-butyl-3-methylimidazolium hexafluorophosphate or butylpyridinium hexafluorophosphate is mixed with solvent chloroform to form an oil phase, and the oil phase enters from the top of the third extraction tower, the tetrafluoroborate is dissolved in water to form a water phase, and the water phase enters from the bottom of the tower. In the third extraction tower, the oil phase and the water phase are in countercurrent contact to generate 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate which enters the oil phase, and the generated hexafluorophosphate enters the water phase. Recycling the water phase, and distilling the oil phase to recover the solvent to obtain purified 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate.

The reaction occurring in the full back-mixing tank reactor is specifically illustrated by taking 1-butyl-3-methylimidazolium phosphate or butylpyridinium hexafluorophosphate and potassium tetrafluoroborate as raw materials according to the examples of the present invention, and it should be noted that the examples described below are illustrative only and are not to be construed as limiting the present invention. The reaction equation of 1-butyl-3-methylimidazolium phosphate or butylpyridinium hexafluorophosphate with potassium tetrafluoroborate is:

According to the examples of the present invention, 1-butyl-3-methylimidazolium hexafluorophosphate or butylpyridinium hexafluorophosphate, which is an oil phase, is dissolved in water, and the resultant 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate is dissolved in water, and as the reaction proceeds, the oil phase gradually disappears until the reaction is completed, to obtain a mixed solution of 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate and potassium hexafluorophosphate. After the reaction is finished, the mixture of 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridine tetrafluoroborate and potassium hexafluorophosphate is sent to a second extraction tower, and a small amount of chloroform is added into the whole system. In the extraction tower, chloroform flows from top to bottom, a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate and potassium hexafluorophosphate flows from bottom to top, countercurrent contact occurs, and the 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate is enriched in the chloroform, and the potassium hexafluorophosphate is enriched in water. The potassium hexafluorophosphate aqueous solution is recycled. Separating and purifying the mixture of the 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate and the chloroform which flows out from the bottom of the tower through a second distillation tower, recycling the recovered chloroform, and extracting the 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate in the bottom of the second distillation tower.

According to the embodiment of the present invention, the operation conditions of the reactor, the second extraction column or the second distillation column are not particularly limited, so long as the requirements can be satisfied, the person skilled in the art can flexibly select according to the actual needs, the feed flow rate or the reaction temperature of the materials in the reactor, the second extraction column or the second distillation column, etc. are also not particularly limited, so long as the reaction or purification can be made complete, and the person skilled in the art can flexibly select according to the actual needs.

According to the embodiment of the invention, the ionic liquid can be any one or any combination of 1-butyl-3-methylimidazole halogen salt, butylpyridine halogen salt, 1-butyl-3-methylimidazole hexafluorophosphate, butylpyridine hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate, so long as the ionic liquid can meet the requirements, and the ionic liquid can be flexibly selected according to actual needs by a person skilled in the art.

In another aspect of the invention, the invention provides an apparatus for preparing the ionic liquid as described above. According to an embodiment of the invention, referring to fig. 1, the apparatus comprises: the rectifying tower 100, wherein a first cation donor inlet 110 is arranged at the top of the rectifying tower 100, and a first anion donor inlet 120 and a first product outlet 130 are arranged at the bottom of the rectifying tower 100. The inventor finds that the rectifying tower device has wide sources, can prepare the ionic liquid by the heterogeneous countercurrent contact method in the rectifying tower, has simple and convenient operation and is beneficial to realizing large-scale production.

According to the embodiments of the present invention, the above-mentioned rectifying tower is consistent with the foregoing description, and will not be repeated herein, and the rectifying tower includes structures that a conventional rectifying tower should have, such as a cylinder, a tray or packing, a skirt, etc.

According to an embodiment of the present invention, the first cation donor may be N-methylimidazole or pyridine, etc., and the N-methylimidazole or pyridine is identical to the foregoing description, and will not be described in detail herein; the first anion donor may be a haloalkane, etc., and the haloalkane is consistent with the foregoing description and will not be described in detail herein; the first cation donor and the first anion produce a product which is a mixture of 1-butyl-3-methylimidazole halide salt or butylpyridine halide salt and halogenated alkane, and the 1-butyl-3-methylimidazole halide salt or butylpyridine halide salt is consistent with the previous description, and the formed 1-butyl-3-methylimidazole halide salt or butylpyridine halide salt flows out from the first product outlet without redundant description.

According to an embodiment of the invention, referring to fig. 2, the apparatus further comprises: the extraction column 200 is provided with a second cation donor inlet 210 in communication with the first product outlet 130 at the top and a second anion donor inlet 220 and a second product outlet 230 at the bottom. Therefore, the extraction tower device has wide sources, can be used for preparing the ionic liquid by the heterogeneous countercurrent contact method in the extraction tower, is simple and convenient to operate, can realize continuous production by connecting the extraction tower with the rectifying tower, and is beneficial to realizing large-scale production.

According to an embodiment of the present invention, in order to allow the extraction reaction to proceed smoothly, it is necessary to mix the second cation donor with the first solvent (e.g., chloroform, etc.) to form an oil phase (or heavy phase), send the oil phase into the extraction column together through the second cation donor inlet, and mix the second anion donor with the second solvent (e.g., water, etc.) to form an aqueous phase (or light phase), and send the oil phase (or light phase) into the extraction column together through the second anion donor inlet.

According to the embodiment of the present invention, the above extraction tower is consistent with the foregoing description of the extraction tower, and will not be repeated herein, where the extraction tower includes a structure that a conventional extraction tower should have, and the structure includes a tower body, a turntable, a fixed ring, a variable speed transmission device, etc., taking the turntable type extraction tower as an example.

According to an embodiment of the present invention, the second cation donor may be 1-butyl-3-methylimidazole halide salt or butylpyridine halide salt, and the 1-butyl-3-methylimidazole halide salt or butylpyridine halide salt is consistent with the foregoing description, and will not be described in detail herein; the second anion donor may be hexafluorophosphate or tetrafluoroborate, and the hexafluorophosphate or tetrafluoroborate is the same as that described above, and will not be described in detail herein; the reaction of the second cation donor with the second anion donor produces a product that is 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, butylpyridinium hexafluorophosphate or a mixture of butylpyridinium tetrafluoroborate and a halogen salt (e.g., KCl), and the 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, butylpyridinium hexafluorophosphate or butylpyridinium tetrafluoroborate is consistent with the foregoing description and will not be repeated here; the resulting 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, butylpyridine hexafluorophosphate or butylpyridine tetrafluoroborate flows out from the second product outlet.

According to an embodiment of the invention, referring to fig. 3, the apparatus further comprises: a reactor 300, said reactor 300 being provided with a third cation donor inlet 310, a third anion donor inlet 320 and a third product outlet 330, wherein said third cation donor inlet 310 is in communication 230 with said second product outlet. Therefore, the ionic liquid preparation method has the advantages that the variety of the reactors is more, the sources are wider, the operation of preparing the ionic liquid in the reactors is simple and convenient, and the continuous production can be realized by connecting the reactors with the extraction tower, so that the large-scale production can be realized.

According to the embodiment of the present invention, the location of the third cation donor inlet or the third anion donor inlet is not particularly limited, so long as the third cation and the third anion can be introduced into the reactor, and those skilled in the art can flexibly select according to actual needs, for example, the third cation donor inlet or the third anion donor inlet may be disposed at the top of the reactor or may be disposed at a middle position of the reactor.

According to the embodiments of the present invention, the kind of the reactor is not particularly limited as long as it can meet the requirements, and those skilled in the art can flexibly select according to actual needs. In some embodiments of the invention, the reactor is a full back-mixing kettle reactor, thereby having simple structure and convenient operation. In other embodiments of the invention, the type of reactor is a third extraction column, whereby the structure is simple, the operation is convenient, and the third extraction column is consistent with the previous description. According to the embodiment of the invention, the full back-mixing kettle type reactor comprises a reactor body, a stirring paddle, a reactor jacket and a structure which is needed to be provided for a conventional reactor, wherein steam and cooling water are introduced into the reactor jacket so as to prevent the temperature in the reactor from being too high, and the reaction is smoothly carried out.

According to an embodiment of the present invention, the third cation donor may be 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridinium hexafluorophosphate, and the 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridinium hexafluorophosphate is consistent with the foregoing description, and will not be described in detail herein; the third anion donor may be a tetrafluoroborate salt, and the tetrafluoroborate salt is in accordance with the foregoing description and will not be described in detail herein; the reaction of the third cation donor with the third anion donor produces a product which is 1-butyl-3-methylimidazolium tetrafluoroborate or a mixture of butylpyridinium tetrafluoroborate and hexafluorophosphate and which flows out from the third product outlet, and the 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate and hexafluorophosphate are in accordance with the foregoing and will not be described in detail herein.

According to an embodiment of the invention, referring to fig. 4, the apparatus further comprises: a first anion donor recovery assembly 140; a first material inlet 141 and a first material outlet 142 are provided in communication with the rectifying column. Therefore, the excessive first anion donor can be recovered, and the device has the advantages of simple structure, simple and convenient operation and lower cost.

According to an embodiment of the present invention, referring to fig. 4, between the rectifying column 100 and the extracting column 200, further comprising: a first product purification assembly 150 is provided with a fourth material inlet 151 in communication with the first product outlet 130, a sixth material outlet 153 in communication with the first anion donor inlet 120, and a seventh material outlet 152 in communication with the second cation donor inlet 210. Thus, the first anion donor can be effectively separated from the product 1, and the first anion donor enters the rectifying tower to circularly participate in the reaction.

According to an embodiment of the present invention, in order to obtain the product 2 with higher purity, referring to fig. 4, between the extraction 200 column and the reactor 300, further comprises: a second product purification assembly 240 having a second material inlet 241 in communication with the second product outlet 230, a second material outlet 242 in communication with the extraction column 200, and a third material outlet 243 in communication with the third cation donor inlet 310. Thereby, separation and purification of the product 2 can be achieved and the separated product 2 is led to the reactor for further processing steps.

According to an embodiment of the present invention, in order to obtain the product 3 with higher purity, referring to fig. 4, the reactor 300 further comprises: a third product purification assembly 340 is provided with a third material inlet 341 in communication with the third product outlet 330, a fourth material outlet 342 in communication with the extraction column 200, and a fifth material outlet 343.

According to an embodiment of the present invention, referring to fig. 5, the first product purification assembly 150 may be a reboiler, whereby separation of the product 1 from the first anion donor can be achieved and the first anion donor can be gasified into a gas phase and recycled into the rectifying column.

In order to avoid damage to the extraction column due to excessive temperatures of product 1, in accordance with an embodiment of the present invention, product 1 needs to be cooled, and referring to fig. 5, the first product purification assembly 150 is followed by a second cooler 160, and product 1 is stored in a first buffer tank 170 after being cooled, and is fed from a second cation donor inlet 210 to the extraction column 200 by a first pump 180. Therefore, the operation is simple, and the damage caused by the excessive temperature in the pipeline or the reactor can be effectively avoided.

In accordance with an embodiment of the present invention, and with reference to fig. 5, the second product purification assembly 240 is a first distillation column, which is consistent with the foregoing description and will not be described in detail herein. According to an embodiment of the present invention, referring to fig. 5, the mixture of the product 2 and the first solvent flows out from the second product outlet 230, passes through the storage of the second buffer tank 270, and is sent to the first distillation column 240 by the second pump 280 for separation and purification, thereby obtaining the product 2 with higher yield. The first distillation column is provided with a first column bottom reboiler at the bottom and a third cooler 244, a third buffer tank 245 and a third pump 246 at the top.

According to the embodiment of the invention, the first distillation tower comprises the first tower bottom reboiler, the third cooler, the third buffer tank and the second pump, and further comprises parts which are needed to be provided for a conventional distillation tower, and the parts are not repeated herein; according to the embodiment of the present invention, the operation conditions for performing the separation and purification in the first distillation column are not particularly limited as long as the separation and purification effect can be made good, and those skilled in the art can flexibly select according to actual needs.

According to an embodiment of the present invention, referring to fig. 4 and 5, the third product purification assembly 340 includes a second extraction column 350 and a second distillation column 360, whereby the purity of the obtained product 3 is high, and is suitable for mass production.

The second extraction column and the second distillation column are consistent with the foregoing description and include the structure and components that a conventional extraction column should have, and will not be described in detail herein. Referring to fig. 5, according to an embodiment of the present invention, the second extraction column 350 and the second distillation column 360 further include: the fourth buffer tank 370 and the fourth pump 380, the second distillation column 360 further includes a fourth cooler 361, a fifth buffer tank 362, a fifth pump 363, and structures and components that a conventional distillation column should have, and will not be described in detail herein. Therefore, the structure is simple, the operation is convenient, and the use performance is better.

According to the embodiment of the invention, the ionic liquid is prepared by adopting the device, products in the reaction process can be recycled, the cost is saved, the products are environment-friendly, the environment is not polluted, the operation is simple and convenient, the realization is easy, the yield is higher, the reaction and the purification can be changed into a linked production line, the determination of key quality control points in the production is facilitated, and the device is suitable for industrial application and large-scale production.

The reaction of the apparatus for preparing an ionic liquid according to the present application will be described below by taking the example of continuous production in the apparatus, in which the first cation donor is pyridine, the first anion donor is chlorobutane, the second anion donor is potassium hexafluorophosphate, and the third anion donor is potassium tetrafluoroborate, and the reaction equation is consistent with the foregoing description, and will not be repeated here. It should be noted that the embodiments described below are exemplary only for explaining the present invention, and are not to be construed as limiting the present invention.

Specifically, referring to fig. 5, chlorobutane enters the reboiler 150 from the fourth material inlet 151, flows out from the sixth material outlet 153 after gasification and enters the rectifying column 100 from the first anion donor inlet 120 to form an ascending gas phase, and is in countercurrent contact with pyridine of a liquid phase entering the rectifying column 100 from the first cation donor inlet 110, wherein excessive chlorobutane flows out from the top of the column, enters the first cooler 143 through the first material inlet 141 to be cooled, then enters the buffer tank 144, a part of chlorobutane is extracted from the first material outlet 142, and the other part of chlorobutane enters the rectifying column 100 through the eighth material outlet 145 to be recycled. The butyl pyridinium chloride product obtained by the reaction flows out through the first product outlet 130, enters the reboiler 150 as a heat source to heat chlorobutane to gasify and then separate from the chlorobutane, flows out from the seventh material outlet 152, is cooled by the second cooler 160, is stored in the first buffer tank 170, and is extracted from the first sampling port 190 by the first pump 180, and the other part is sent into the extraction tower 200 from the second cation donor inlet 210.

In the extraction column 200, an amount of chloroform is added at the second cation donor inlet 210 and mixed with butylpyridinium chloride to form an oil phase into the extraction column 200, and an aqueous potassium hexafluorophosphate solution is introduced as an aqueous phase into the extraction column 200 from the second anion donor inlet 220. The oil-water two-phase countercurrent contact reaction is carried out, the generated potassium chloride and water form a new water phase to be enriched at the tower top and enter an evaporation recovery device through an outlet 260 to be recovered, the generated butyl pyridine hexafluorophosphate and chloroform form a new oil phase to be enriched at the tower bottom and flow out from a second product outlet 230, the new oil phase is sent into a first distillation tower 240 from a second material inlet 241 to be separated and purified through a second pump 280 after being stored in a second buffer tank 270, wherein the chloroform is gasified by a first tower bottom reboiler, then the chloroform gas rises and flows out from the tower top, is cooled by a third cooler 244 and enters a third buffer tank 245, one part of the chloroform is sent into the first distillation tower 240 to be continuously involved in separation and purification by a third pump 246, and the other part of the chloroform is sent into an extraction tower 200 through a second material outlet 242 to be recycled as a solvent. Purified butylpyridinium hexafluorophosphate flows out of the third material outlet 243, one portion is withdrawn from the second sampling port 247, and another portion enters the reactor 300 through the third cation donor inlet 310.

In the reactor 300, the aqueous solution of potassium tetrafluoroborate enters the reactor 300 from the third anion donor inlet 320, after the butyl pyridine hexafluorophosphate reacts with the aqueous solution of potassium tetrafluoroborate completely, the mixture of butyl pyridine tetrafluoroborate, potassium hexafluorophosphate and water flows out from the third product outlet 330 and enters the second extraction tower 350 through the third material inlet 341, chloroform enters the second extraction tower 350 from the fifth material inlet 351, potassium hexafluorophosphate and water are enriched at the top of the tower and flow out from the fourth material outlet 342 and then enter the extraction tower 200 through the second anion donor inlet 220 for recycling, the mixture of butyl pyridine tetrafluoroborate and chloroform is enriched at the tower kettle and flows out from the ninth material outlet 344, after the mixture of butyl pyridine tetrafluoroborate and potassium tetrafluoroborate is stored in the fourth buffer tank 370, the mixture of butyl pyridine tetrafluoroborate and the potassium hexafluorophosphate is sent into the second distillation tower 360 for separation and purification by the fourth pump 380, wherein the second tower kettle gasifies the chloroform, after the chloroform gas rises and flows out from the fourth cooler 363, enters the fifth buffer tank 362, a part of the chloroform is sent to the second distillation tower 351 by the fifth pump 361, and a part of the mixture of butyl pyridine and the chloroform is continuously sent out from the fourth distillation tower 350 into the fifth distillation tower 350 for separation and purification after the mixture of the butyl pyridine and the mixture flows out from the fourth material outlet 343.

According to the embodiment of the invention, in the general method for preparing the ionic liquid, a large amount of waste acid, waste gas or heavy metal salt is generated, which threatens the environment, and the preparation of the high-purity (halogen-free) ionic liquid usually uses special ion exchange resin, so that the regeneration cost of the special ion resin is high, and the industrial process of the ionic liquid is restricted. In the application, the ionic liquid is prepared by adopting the device and the method, the operation is simple and convenient, the continuous production can be realized, the reaction and the purification can be changed into a linked production line, the key quality control point in the production can be conveniently determined, the yield is higher, the product can be recycled, the environment is not polluted by waste acid, waste gas or heavy metal salt, the yield of the higher ionic liquid can be achieved without adopting special equipment, the purity of the obtained ionic liquid is higher, the cost is lower, and the method is suitable for industrial application.

Specific examples:

example 1:

the preparation method of the ionic liquid comprises the following steps:

1. preparation of 1-butyl-3-methylimidazole chloride or butylpyridine chloride

In the rectifying tower, liquid-phase N-methylimidazole or pyridine and gaseous-phase chlorobutane are in countercurrent contact to react to prepare 1-butyl-3-methylimidazole chloride or butylpyridine chloride.

2. Preparation of 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate

In the extraction tower, the 1-butyl-3-methylimidazole chloride or butylpyridine chloride in the oil phase is in countercurrent contact with potassium hexafluorophosphate in the water phase to react to prepare the 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate.

3. Preparation and purification of 1-butyl-3-methylimidazolium tetrafluoroborate or butylpyridinium tetrafluoroborate

In the full back mixing kettle type reactor, 1-butyl-3-methylimidazole hexafluorophosphate or butylpyridine hexafluorophosphate reacts with potassium tetrafluoroborate, and 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate causes the oil phase to disappear. And (3) entering a second extraction tower, extracting 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate from the water phase by using a chloroform solvent, and recycling after the chloroform is distilled. The aqueous phase potassium hexafluorophosphate is recycled.

Example 2:

preparing 1-butyl-3-methylimidazole chloride salt by adopting batch operation:

the preparation of the 1-butyl-3-methylimidazole chloride salt uses a rectifying column (namely a rectifying tower) with the diameter of 2cm and the length of 1m, the filler is ceramic raschig rings, and the filler is fully wetted by N methylimidazole. The bottom of the rectifying column is a 500ml flask with a heating sleeve (i.e. reboiler) and a thermometer, the top end of the rectifying column is connected with a reflux condenser pipe for total reflux, and the upper end of the reflux condenser pipe is connected with a constant pressure dropping funnel. To the flask was added 300ml of chlorobutane and the heating temperature of the electric mantle was 90 ℃.40g of N methylimidazole was dropped in the dropping funnel at a dropping rate of 1 to 2 drops per second. After the completion of the dripping, the reaction was carried out for 24 hours, the complete flow of N-methylimidazole into the bottom of the reactor was ensured, the reaction kettle was checked for the absence of N-methylimidazole by High Performance Liquid Chromatography (HPLC), and the reaction kettle was distilled to recover excess chlorobutane. Vacuum distillation is carried out at 90 ℃ and 0.1MPa, non-volatile components are collected, and 1-butyl-3-methylimidazole chloride is obtained, wherein the yield is 100.7%.

Examples 3 to 6

The procedure of example 2 was followed except for changing the amount of N-methylimidazole added, the temperature of the jacket at the bottom of the reactor, and the packing of the rectification column, and the results of the preparation of 1-butyl-3-methylimidazole chloride salt are shown in Table 1:

TABLE 1 yields of 1-butyl-3-methylimidazole chloride under various conditions

Examples 7 to 8

Batch operation to make butylpyridinium chloride:

the procedure of example 2 was followed except that N-methylimidazole was changed to pyridine in different amounts, and the results are shown in Table 2:

TABLE 2 yields of butylpyridinium chloride at various pyridine additions

Example sequence number	Pyridine addition (g)	Yield rate
			7	45	97.7％
8	50	99.4％

Example 9

Preparing 1-butyl-3-methylimidazole hexafluorophosphate by adopting a vibrating sieve plate extraction tower to continuously operate:

the diameter of the extraction tower is 8cm, and the height is 1m. 184g of potassium hexafluorophosphate was dissolved in 2L of water (concentration: 0.5 mol/L), 174g of 1-butyl-3-methylimidazole chloride was dissolved in 1L of chloroform (concentration: 1 mol/L). The aqueous phase is added at the bottom and overflows from the top. The oil phase is added from the top of the tower and taken out from the bottom of the tower. The oil phase is used as a continuous phase, the water phase is used as a disperse phase, and the oil phase and the water phase are in countercurrent contact reaction in the extraction tower. And detecting the content of chloride ions in the oil phase, and considering that the reaction is complete when the content of chloride ions in the oil phase is less than 50 ppm. Otherwise, the reaction is circulated until the reaction is complete. And (3) distilling the oil phase, recovering chloroform, wherein the nonvolatile component in the distillation tower kettle is 1-butyl-3-methyl hexafluorophosphate, and the yield is 95.4%.

Examples 10 to 11

The procedure of example 9 was followed except for changing the amounts of 1-butyl-3-methylimidazole chloride and potassium hexafluorophosphate, and the results are shown in Table 3:

TABLE 3 yield of 1-butyl-3-methylimidazole hexafluorophosphate by varying the amount of raw materials added

Examples 12 to 14

The butyl pyridine hexafluorophosphate is prepared by adopting a vibrating sieve plate extraction tower to continuously operate:

the procedure of example 9 was followed except that the reaction was changed to a different amount of butylpyridinium chloride and potassium hexafluorophosphate. The results are shown in Table 4:

TABLE 4 yield of butylpyridinium hexafluorophosphate by varying the amount of raw materials added

Example sequence number	Butyl pyridine chloride (g)	Potassium hexafluorophosphate (g)	Yield rate
				12	86	97	94.3％
13	129	145	93.6％
				14	172	184	95.3％

Example 15

Synthesizing 1-butyl-3-methylimidazole tetrafluoroborate by adopting a full back mixing kettle reactor:

142g of 1-butyl-3-methylimidazole hexafluorophosphate, 63g of potassium tetrafluoroborate, 2L of water and stirring at room temperature were added to the 3L reactor. After the reaction for 24 hours, the oil phase disappeared and the reaction was ended. The reaction system is all water phase and enters a vibration sieve plate extraction tower. In the extraction tower, chloroform is used as an extractant, an oil phase is a continuous phase, a water phase is a disperse phase, and oil-water two phases are in countercurrent contact in the extraction tower. The chloroform dosage was 1L and the Thin Layer Chromatography (TLC) detected the absence of organic ions in the aqueous phase, which was considered complete, otherwise the aqueous phase was recycled. After the extraction is completed, the oil phase is distilled, chloroform is recovered, the nonvolatile component in the distillation tower kettle is 1-butyl-3-methyl tetrafluoroborate, and the yield is 93.1%. The water phase is potassium hexafluorophosphate and is recycled.

Examples 16 to 17

The procedure of example 15 was followed except for changing the amounts of 1-butyl-3-methylimidazole hexafluorophosphate and potassium tetrafluoroborate, and the results are shown in Table 5:

TABLE 5 yield of 1-butyl-3-methylimidazole tetrafluoroborate by varying the amount of raw materials added

Examples 18 to 20

The procedure of example 15 was followed except that the reactants were changed to different amounts of butylpyridinium hexafluorophosphate and potassium tetrafluoroborate. The results are shown in Table 6:

table 6 yield of butylpyridinium tetrafluoroborate by varying the amount of raw materials added

Example sequence number	Butyl pyridine hexafluorophosphate (g)	Potassium tetrafluoroborate (g)	Yield rate
				18	141	63	94.4％
19	105	48	95.1％
				20	70	32	96.3％

Comparative example 1:

93g of chlorobutane, 82g N methylimidazole and 80 ℃ were added to a 500ml three-necked flask with a reflux condenser, a thermometer and a stirrer, and reacted for 72 hours at 80 ℃, and the excess reactant was distilled under reduced pressure to obtain ionic liquid 1-butyl 3 methylimidazole chloride. The yield was 94%. 174g of 1-butyl 3-methylimidazole chloride, 110g of sodium tetrafluoroborate,300ml of water was reacted at 100℃for 24 hours, extracted three times with 40ml of methylene chloride, the organic layers were combined and washed with water to AgNO ₃ Detecting no chloride ion, evaporating to dryness to obtain ionic liquid 1-butyl 3-methylimidazole tetrafluoroborate with a yield of 24%. 174g of 1-butyl 3-methylimidazole chloride, 185g of sodium hexafluorophosphate, 1000ml of water and 100℃were reacted for 8 hours to give a large amount of oil. Separating, extracting the water layer with 200ml dichloromethane twice, mixing the organic layers, and washing the organic layers with water to AgNO ₃ Detecting no chloride ion, evaporating to dryness to obtain ionic liquid 1-butyl 3-methylimidazole hexafluorophosphate, and the yield is 84%.

Comparative example 2:

1-butyl-3-methylimidazole chloride was prepared in accordance with the method of comparative example 1. 214.2g of 1-butyl-3-methylimidazole chloride is dissolved in 300g of absolute ethyl alcohol, 50.4g of KOH is dissolved in 250g of absolute ethyl alcohol, the mixture is slowly added into a 1L round-bottomed flask, the mixture is reacted for 12 hours at room temperature under sufficient stirring, KCl precipitate is removed after the reaction is finished by filtration, and 1-butyl-3-methylimidazole alkali solution with the content of 28% is obtained, and the yield is 95%. A glass column with the size phi of 16 multiplied by 500mm is filled with 201 multiplied by 7 strong base anion exchange resin (chlorine type), the filling height is 450mm, the resin is washed by 100ml of deionized water, then washed by 100ml of 4% NaOH, then washed by 150ml of 16% NaOH, then washed by 100ml of 4% NaOH, finally washed by 200ml of deionized water to be neutral, and the pretreatment of resin transformation is completed. An amount of water was added to the 1-butyl-3-methylimidazole alkali solution so that the hydroxide concentration was 0.5mol/L. At this time, the mass ratio of chlorine ions to quaternary ammonium base in the solution was 1500ppm, and the mass ratio of potassium ions to quaternary ammonium base was 1020ppm. The aqueous solution was passed through the ion exchange column at a flow rate of 900ml/h (10 BV/h), collected from the time when the effluent became alkaline, and after the total flow of the solution, the resin was rinsed with pure water until it was washed to neutrality, and the rinse solution was collected. A glass column having a size of phi 16X 500mm was packed with 001X 12 strong acid type anion exchange resin (hydrogen form) to a packing height of 450mm. The resin was first washed with 100ml of deionized water, then rinsed with 150ml of 5% hcl, and finally washed to neutrality with 200ml of deionized water, completing the resin pretreatment. 150ml of 5% 1-butyl are then used Eluting with aqueous solution of-3-methylimidazole chloride, and washing with 200ml deionized water until the effluent is treated with AgNO ₃ Detecting no sediment, and finishing the conversion of the resin surface. The 1-butyl-3-methylimidazole alkali solution obtained in the previous step flows through the ion exchange column at a flow rate of 900ml/h (10 BV/h) to remove potassium ions. Collecting the effluent from the process of alkaline reaction, eluting the resin with pure water after the solution is completely passed through the process until the resin is washed to be neutral, and collecting the eluent to obtain purified 1-butyl-3-methylimidazole alkali liquor. Adding 88g of tetrafluoroboric acid into the purified 1-butyl-3-methylimidazole alkali liquor under stirring to neutralize the solution, thus obtaining the 1-butyl-3-methylimidazole tetrafluoroborate. The solvent is distilled off under reduced pressure to obtain purified ionic liquid 1-butyl-3-methylimidazole tetrafluoroborate with 89 percent of yield.

By comparing comparative example 1 with example 2, the yield of the 1-butyl-3-methylimidazole chloride salt prepared by the method is obviously higher than that of comparative example 1, the reaction time is shorter than that of comparative example 1, the effect is better, no toxic solvent is needed, and the method is environment-friendly. By comparing comparative example 2 with examples 15, 16 or 17, it was found that the yield of 1-butyl-3-methylimidazole tetrafluoroborate prepared by the method of the present application was significantly higher than that of comparative example 2, and the operation was simple and convenient, without using a special ion exchange resin, and the yield was higher and the effect was better. Therefore, the method for preparing the ionic liquid is more beneficial to industrial production, the process flow is short, and a plurality of products can be produced on one production line.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. A method of preparing an ionic liquid comprising:

In a first step, in a rectifying tower, carrying out heterogeneous countercurrent contact on N-methylimidazole or pyridine in a liquid phase and halogenated alkane in a gas phase so as to obtain a product 1, wherein the product 1 is 1-butyl-3-methylimidazole halogen salt or butylpyridine halogen salt; at least part of the product 1 is extracted and sent to an extraction tower;

mixing at least part of the product 1 with chloroform in the extraction tower to form an oil phase, mixing hexafluorophosphate or tetrafluoroborate with water to form an aqueous phase, enabling at least part of the product 1 of the oil phase to be in out-of-phase countercurrent contact with hexafluorophosphate of the aqueous phase or tetrafluoroborate of the aqueous phase to generate a product 2, sending the product 2 into a first distillation tower for separation and purification so as to obtain 1-butyl-3-methylimidazolium hexafluorophosphate or butylpyridinium hexafluorophosphate, and sending at least part of the product 2 into a total back-mixing kettle type reactor or a third extraction tower;

thirdly, mixing at least part of the product 2 with chloroform in the total back mixing kettle type reactor or the third extraction tower to form an oil phase, mixing tetrafluoroborate with water to form an aqueous phase, enabling at least part of the product 2 of the oil phase to be in out-of-phase countercurrent contact with tetrafluoroborate of the aqueous phase to form a product 3, wherein the product 3 is 1-butyl-3-methylimidazole tetrafluoroborate or butylpyridine tetrafluoroborate mixture, and sending the product 3 into a second distillation tower for separation and purification so as to obtain the 1-butyl-3-methylimidazole tetrafluoroborate or the butylpyridine tetrafluoroborate.

2. The method according to claim 1, wherein the 1-butyl-3-methylimidazole halogen salt is 1-butyl-3-methylimidazole chloride salt and the butylpyridine halogen salt is butylpyridine chloride salt;

the haloalkane is chlorobutane.

3. An apparatus for preparing the ionic liquid of any one of claims 1 to 2, comprising:

the rectifying tower, rectifying tower top is provided with first cation donor entry, and the bottom is provided with first anion donor entry and first product export.

4. A device according to claim 3, further comprising:

the extraction tower, the extraction tower top be provided with the second cation donor entry that is linked together with first product export, the bottom is provided with second anion donor entry and second product export.

5. The apparatus as recited in claim 4, further comprising:

a reactor provided with a third cation donor inlet, a third anion donor inlet, and a third product outlet, wherein the third cation donor inlet is in communication with the second product outlet.

6. The apparatus as recited in claim 5, further comprising:

The first anion donor recovery assembly is provided with a first material inlet and a first material outlet which are communicated with the rectifying tower;

a first product purification assembly provided with a fourth material inlet in communication with the first product outlet, a sixth material outlet in communication with the first anion donor inlet, and a seventh material outlet in communication with the second cation donor inlet;

a second product purification assembly provided with a second material inlet in communication with the second product outlet, a second material outlet in communication with the extraction column, and a third material outlet in communication with the third cation donor inlet;

and the third product purification assembly is provided with a third material inlet communicated with the third product outlet, a fourth material outlet communicated with the extraction tower and a fifth material outlet.