Ionic liquid with low hydrogen solubility and preparation method and application thereof

Abstract

The invention provides an ionic liquid with low hydrogen solubility and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing N-methylimidazole, alkyl halide and a solvent I, cooling in an ice bath, and carrying out an N-alkylation reaction to obtain an alkyl imidazolium halide mixed solution; (2) carrying out reduced pressure distillation on the alkyl imidazolium halide mixed solution to remove the solvent I, and carrying out vacuum drying to obtain an intermediate product alkyl imidazolium halide; (3) mixing alkyl imidazolium halide, bis (trifluoromethane sulfonic acid) imine metal salt and a solvent II, and carrying out anion exchange reaction to obtain an imidazole ionic liquid crude product; and (4) washing and drying the imidazole ionic liquid crude product to obtain the ionic liquid with low hydrogen solubility. The ionic liquid with low hydrogen solubility is low in hydrogen solubility, and the stability and high efficiency of an ion compressor in the long-period operation process are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas compressors, in particular to an ionic liquid with low hydrogen solubility and a preparation method and application thereof. BACKGROUND

[0002] The development of the world today is facing the challenge of serious environmental problems. Hydrogen energy, as a zero-emission, pollution-free and sustainable green energy, is considered an important way to solve energy problems in the new century. With the rapid development of China's hydrogen energy industry, the demand for hydrogen refueling station infrastructure is increasing rapidly, and it is developing from 35MPa to 70MPa. Whether to have safe, stable and efficient hydrogen pressurizing and filling equipment has become an important factor affecting the development of the industry, and how to realize a low-cost, high-pressure and large-capacity hydrogen compressor is the top priority.

[0003] The hydrogen compressor commonly used in hydrogen refueling stations at present is a diaphragm compressor, which has a short service life under frequent start-up and is difficult to achieve large capacity, which is the main problem it faces. The emergence of ionic compressors provides a new way to solve this problem. Compared with traditional hydrogen compressors, ionic compressors use ionic liquids to build liquid pistons, which directly contact with the compressed working substance (hydrogen) for gas compression. During the compression process, the hydrogen gas is not contaminated, making the compression process close to isothermal compression, which can reduce the compressor discharge temperature, thereby improving the reliability and saving energy. At the same time, ionic compressors have fewer moving parts and are simpler in structure than ordinary compressors, and can serve for a long time without maintenance. Based on these advantages, ionic compressors are expected to become a good solution for hydrogen pressurization in future high-pressure hydrogen refueling stations.

[0004] The key to the excellent performance of the ionic compressor is the ionic liquid, which undertakes multiple tasks such as compression, lubrication, cooling and sealing in the ionic compressor. More importantly, it is necessary to keep the solubility of the ionic liquid to hydrogen very low to meet the stability and high efficiency of the ionic compressor during long-term operation. SUMMARY

[0005] The present application provides an ionic liquid with low hydrogen solubility and a preparation method and application thereof to solve the problems mentioned in the background.

[0006] In a first aspect, the present application provides a preparation method of an ionic liquid with low hydrogen solubility, which comprises the following steps: (1) mixing N-methyl imidazole, halogenated alkane and solvent one, ice bath cooling, N-alkylation reaction to obtain an alkyl imidazolium halide mixed solution; (2) removing solvent one from the alkyl imidazolium halide mixed solution by vacuum distillation, vacuum drying to obtain an intermediate product alkyl imidazolium halide; (3) mixing the alkyl imidazolium halide and the bis(trifluoromethanesulfonate) imide metal salt and a solvent II to perform an anion exchange reaction to obtain the imidazole ionic liquid crude product; (4) washing and drying the imidazole ionic liquid crude product to obtain the ionic liquid with low hydrogen solubility.

[0007] Optionally, the halogen in the alkyl halide is one of fluorine, chlorine and bromine, and the alkane in the alkyl halide is one of methane, ethane, propane, butane, pentane, hexane, heptane, octane and cyclohexane. The solvent I is one or more of acetonitrile, acetone, butanone, petroleum ether and ethyl acetate.

[0008] Optionally, the molar ratio of the alkyl halide to the N-methyl imidazole is 1:1-1:1.5, and the mass of the solvent I is 20-200% of the sum of the masses of the alkyl halide and the N-methyl imidazole.

[0009] Optionally, the temperature of the N-alkylation reaction is 20-90℃, and the time is 2-24h.

[0010] Optionally, the molar ratio of the imidazolium halide to the bis(trifluoromethanesulfonate) imide metal salt is 1:1-1:1.5.

[0011] Optionally, the bis(trifluoromethanesulfonate) imide metal salt is lithium bis(trifluoromethanesulfonate) imide and / or zinc bis(trifluoromethanesulfonate) imide.

[0012] Optionally, the solvent II is one or more of acetonitrile, acetone, butanone, petroleum ether and ethyl acetate, and the mass of the solvent II is 40-200% of the sum of the masses of the imidazolium halide and the bis(trifluoromethanesulfonate) imide metal salt.

[0013] Optionally, the temperature of the anion exchange reaction is 20-90℃, and the time is 10-60h.

[0014] In a second aspect, the application provides a ionic liquid with low hydrogen solubility, which is prepared by the above method.

[0015] In a third aspect, the application provides the use of the ionic liquid with low hydrogen solubility in the field of hydrogen compressor technology.

[0016] The ionic liquid with low hydrogen solubility, the preparation method and the use thereof provided by the application realize the preparation of the ionic liquid with low hydrogen solubility, and have the following beneficial effects compared with the prior art: (1) The application realizes the synthesis of ionic liquid with low hydrogen solubility. By selecting halogenated alkyl with different carbon chain length as alkylating agent and N-methyl imidazole for N-alkylation reaction, intermediate product alkyl imidazolium halide is obtained. The alkyl imidazolium halide is ion exchanged with bis(trifluoromethanesulfonic acid) imine metal salt in solvent two to obtain ionic liquid with low hydrogen solubility. The ionic liquid provided by the application is almost non-volatile at room temperature and normal pressure, which means that during the compression process of the hydrogen compressor, the liquid component will not vaporize and enter the hydrogen stream, and the output hydrogen will not be contaminated by hydrocarbons or other volatile substances. The ionic liquid provided by the application has stable structure, wide working temperature range and good environmental adaptability. The charge distribution of the ions in the structure of the ionic liquid provided by the application is relatively concentrated, and they will produce strong electrostatic attraction (Coulomb force) between them, which has small solubility to hydrogen, avoids the loss and pollution of hydrogen during the compression process, improves the working efficiency of the hydrogen compressor, and is conducive to the long-period stable and efficient operation of the hydrogen compressor, reduces the energy consumption and reduces the maintenance cost of the hydrogen compressor.

[0017] (2) The application generates ionic liquid containing nanomaterials in situ through one-step reaction by solvothermal method. In the reaction process, p-phenylenediamine is condensed with salicylaldehyde to generate imine nanomaterials containing carbon-nitrogen double bond. At the same time, chemical bond is generated between the ionic liquid and the nanomaterials in the hydrothermal reaction, and the nanoparticles are introduced into the structure of the ionic liquid. The low hydrogen solubility ionic liquid obtained by one-step reaction interacts with the internal structure of the nanomaterials, instead of being obtained by physical mixing, which is more stable. The introduction of nanomaterials into the ionic liquid fills part of the free volume in the ionic liquid, and its specific surface area can also change the transfer path and dissolution behavior of hydrogen in the ionic liquid, which can further reduce the solubility of hydrogen in the ionic liquid, thereby ensuring that the ionic liquid can replace the piston to directly contact with hydrogen for hydrogen compression, and the hydrogen will not be contaminated during the compression process, thereby improving the stability and efficiency of the ionic compressor during long-period operation.

[0018] (3) The reaction process of the application is simple and convenient, the reaction conditions are mild, the water content of the target product is low, and the purity reaches more than 99%, which reduces energy consumption and labor consumption, meets the high-purity requirement, and is conducive to industrial production. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0020] In a first aspect, the present application provides a preparation method of ionic liquid with low hydrogen solubility, which comprises the following steps: (1) mixing N-methyl imidazole, alkyl halide and solvent one, cooling in an ice bath, and performing N-alkylation reaction to obtain an alkyl imidazolium halide mixture; (2) removing solvent one from the alkyl imidazolium halide mixture by reduced pressure distillation, and vacuum drying to obtain an intermediate product alkyl imidazolium halide; (3) mixing the alkyl imidazolium halide, bis(trifluoromethanesulfonic acid) imide metal salt and solvent two, and performing anion exchange reaction to obtain an imidazole ionic liquid crude product; (4) washing and drying the imidazole ionic liquid crude product to obtain ionic liquid with low hydrogen solubility.

[0021] Specifically, N-alkylation reaction is performed between N-methyl imidazole and alkyl halide to obtain an alkyl imidazolium halide mixture. The reaction is performed in an ice bath, and the temperature is kept at 0-5°C. Meanwhile, the alkyl halide is slowly added dropwise under vigorous stirring to avoid local violent reaction. Solvent one is used to facilitate efficient reaction and also serves the purpose of heat dissipation to avoid violent reaction. After the N-alkylation reaction is completed, the alkyl imidazolium halide mixture is washed multiple times with one or more of anhydrous ethanol, deionized water, petroleum ether and diethyl ether, solvent one is removed by reduced pressure distillation, and vacuum drying is performed to obtain an intermediate product alkyl imidazolium halide.

[0022] The alkyl imidazolium halide is mixed with the metal salt of bis(trifluoromethanesulfonic acid) imide and solvent 2 to perform an anion exchange reaction to obtain an imidazole ionic liquid crude product, and the imidazole ionic liquid crude product is washed and dried to obtain the target product, the low-hydrogen-solubility ionic liquid. The purification of the imidazole ionic liquid crude product includes reduced pressure filtration, organic extraction and reduced pressure distillation. The solid impurities in the ionic liquid crude product are removed by reduced pressure filtration, and the ionic liquid mixed solution after removing the solid impurities is purified by extraction to obtain a mixture of the ionic liquid and the extractant, and finally the extractant is distilled out by reduced pressure distillation to obtain the ionic liquid. The purification of the ionic liquid includes reduced pressure filtration, organic extraction and reduced pressure distillation, which are all mature means for purifying ionic liquids in the art, and those skilled in the art have the ability to select appropriate operating conditions and extractants to purify the ionic liquid mixed solution according to the actual working conditions, which will not be described herein.

[0023] The present application realizes the synthesis of the low-hydrogen-solubility ionic liquid by the above-mentioned scheme. By selecting halogenated alkanes with different carbon chain lengths as the alkylating agent to perform N-alkylation reaction with N-methyl imidazole, the intermediate product alkyl imidazolium halide is obtained. The alkyl imidazolium halide is ion exchanged with the metal salt of bis(trifluoromethanesulfonic acid) imide in solvent 2 to obtain the low-hydrogen-solubility ionic liquid. The ionic liquid provided by the present application is almost non-volatile at normal temperature and pressure, which means that during the compression process of the hydrogen compressor, no liquid component will vaporize and enter the hydrogen stream, and the produced hydrogen will not be contaminated by hydrocarbons or other volatile substances. The ionic liquid provided by the present application has a stable structure and a wide working temperature range, and can be applied to a wide temperature range environment, and has good environmental adaptability. The charge distribution of the anion and the cation in the structure of the ionic liquid provided by the present application is relatively concentrated, and they will produce a strong electrostatic attraction (Coulomb force), and the solubility of hydrogen is very small, which avoids the loss and pollution of hydrogen during the compression process, improves the working efficiency of the hydrogen compressor, and is conducive to the long-period stable and efficient operation of the hydrogen compressor, reduces the energy consumption and reduces the maintenance cost of the hydrogen compressor.

[0024] Further, after the anion exchange reaction, the imidazole ionic liquid crude product is obtained, and after purification, p-phenylenediamine and salicylaldehyde are added to the imidazole ionic liquid, ultrasonic stirring is performed for 15-30 min to form a uniform solution, the solution is transferred to a high-pressure reaction kettle, and the solution is reacted at 80-100℃ for 8-16 h in a closed environment, and then naturally cooled to room temperature. The solution is vacuum dried at 60-85℃ until the weight is constant to obtain an ionic liquid containing nanomaterials, i.e. a low-hydrogen-solubility ionic liquid.

[0025] The mass ratio of the imidazole ionic liquid, p-phenylenediamine and salicylaldehyde is 1:0.05:0.05-0.08.

[0026] The imidazolium halide and the metal salt of bis(trifluoromethanesulfonic acid) imide are mixed in a solvent to form a mixture, and the mixture is subjected to anion exchange reaction to obtain the imidazolium salt of bis(trifluoromethanesulfonic acid) imide.

[0027] Optionally, the halogen in the halogenated alkane is one of fluorine, chlorine and bromine, and the alkane in the halogenated alkane is one of methane, ethane, propane, butane, pentane, hexane, heptane, octane and cyclohexane. The solvent I is one or more of acetonitrile, acetone, butanone, petroleum ether and ethyl acetate.

[0028] Optionally, the molar ratio of the halogenated alkane to the N-methyl imidazole is 1:1-1:1.5, and the mass of the solvent I is 20-200% of the sum of the masses of the halogenated alkane and the N-methyl imidazole.

[0029] Optionally, the temperature of the N-alkylation reaction is 20-90℃, and the time is 2-24h.

[0030] Optionally, the molar ratio of the imidazolium halide to the metal salt of bis(trifluoromethanesulfonic acid) imide is 1:1-1:1.5.

[0031] Optionally, the metal salt of bis(trifluoromethanesulfonic acid) imide is lithium bis(trifluoromethanesulfonic acid) imide and / or zinc bis(trifluoromethanesulfonic acid) imide.

[0032] Optionally, the solvent II is one or more of acetonitrile, acetone, butanone, petroleum ether and ethyl acetate, and the mass of the solvent II is 40-200% of the sum of the masses of the imidazolium halide and the metal salt of bis(trifluoromethanesulfonic acid) imide.

[0033] Optionally, the temperature of the anion exchange reaction is 20-90℃, and the time is 10-60h.

[0034] In a second aspect, the application provides an ionic liquid with low hydrogen solubility, which is prepared by the above method.

[0035] In a third aspect, the application provides the use of the ionic liquid with low hydrogen solubility as described above in the field of hydrogen compressor technology.

[0036] Specifically, the ionic liquid with low hydrogen solubility provided by the application is used as a "liquid piston" to contact hydrogen for hydrogen compression, while the solubility in hydrogen is very low, ensuring the pollution-free and lossless compression of hydrogen, and improving the working efficiency of the hydrogen compressor. Compared with traditional compressors, it is easy to achieve high pressure and large displacement, high compression efficiency, low energy consumption, good safety and reliability at high pressure and high temperature, and long-term service. It can also be used as a sealing / cooling medium.

[0037] The following are examples and effect test examples of the application, which further describe the technical solutions and effects of the application, but the protection scope of the application is not limited to these examples. Any changes or equivalent substitutions without departing from the concept of the application are within the protection scope of the application. In addition, if the specific technical operation steps or conditions are not mentioned in the examples, they are carried out according to the technology or conditions described in the general literature or according to the product manual. If the reagents or instruments are not specified by the manufacturer, they are conventional products that can be obtained from the market. Example 1

[0038] A preparation method of an ionic liquid with low hydrogen solubility, the preparation method comprising the following steps: (1) mixing halogenated alkane and solvent one, slowly dropping halogenated alkane, ice bath cooling at 0-5°C, N-alkylation reaction, after dropping, continue stirring at 20°C for 2h, and the reaction is completed. An alkylimidazolium halide mixture is obtained; The solvent one is acetonitrile, the halogenated alkane is bromoethane, the molar ratio of halogenated alkane to N-methyl imidazole is 1:1, and the mass of solvent one is 20% of the sum of the mass of halogenated alkane and N-methyl imidazole.

[0039] (2) removing solvent one from the alkylimidazolium halide mixture by vacuum distillation, and vacuum drying to obtain an intermediate product, alkylimidazolium halide; (3) mixing the alkylimidazolium halide with bis(trifluoromethanesulfonic acid) imide metal salt and solvent two, and performing anion exchange reaction to obtain an imidazole ionic liquid crude product; The solvent two is acetonitrile, and the mass of solvent two is 40% of the sum of the mass of imidazolium halide and bis(trifluoromethanesulfonic acid) imide metal salt; The molar ratio of imidazolium halide to lithium bis(trifluoromethanesulfonic acid) imide salt is 1:1, the temperature of the anion exchange reaction is 20°C, and the time is 10h.

[0040] (4) washing and drying the crude imidazole ionic liquid to obtain the ionic liquid with low hydrogen solubility. Example 2

[0041] A preparation method of the ionic liquid with low hydrogen solubility, comprising the following steps: (1) mixing the haloalkane with solvent one, slowly adding the haloalkane, performing N-alkylation reaction under ice bath cooling at 0-5°C, continuing to stir and reflux the reaction at 50°C for 14 hours after the addition is completed, and ending the reaction to obtain an alkyl imidazolium halide mixture; The solvent one is acetonitrile, the haloalkane is cyclohexyl bromide, the molar ratio of the haloalkane to N-methyl imidazole is 1:2, and the mass of the solvent one is 110% of the sum of the masses of the haloalkane and N-methyl imidazole.

[0042] (2) removing the solvent one from the alkyl imidazolium halide mixture through reduced pressure distillation, vacuum drying, and obtaining an intermediate product alkyl imidazolium halide; (3) mixing the alkyl imidazolium halide with a bis(trifluoromethanesulfonic acid) imide metal salt and a solvent two, performing anion exchange reaction, and obtaining a crude imidazole ionic liquid; The solvent two is acetonitrile, and the mass of the solvent two is 120% of the sum of the masses of the imidazolium halide and the bis(trifluoromethanesulfonic acid) imide metal salt; The molar ratio of the imidazolium halide to the lithium bis(trifluoromethanesulfonic acid) imide salt is 1:2, the temperature of the anion exchange reaction is 50°C, and the time is 40 hours.

[0043] (4) washing and drying the crude imidazole ionic liquid to obtain the ionic liquid with low hydrogen solubility. Example 3

[0044] A preparation method of the ionic liquid with low hydrogen solubility, comprising the following steps: (1) mixing the haloalkane with solvent one, slowly adding the haloalkane, performing N-alkylation reaction under ice bath cooling at 0-5°C, continuing to stir and reflux the reaction at 90°C for 24 hours after the addition is completed, and ending the reaction to obtain an alkyl imidazolium halide mixture; The solvent one is acetonitrile, the haloalkane is cyclohexyl bromide, the molar ratio of the haloalkane to N-methyl imidazole is 1:1.5, and the mass of the solvent one is 200% of the sum of the masses of the haloalkane and N-methyl imidazole.

[0045] (2) removing the solvent one from the alkyl imidazolium halide mixture through reduced pressure distillation, vacuum drying, and obtaining an intermediate product alkyl imidazolium halide; (3) mixing the alkyl imidazolium halide and the metal salt of bis(trifluoromethanesulfonate) imide and a solvent II to perform an anion exchange reaction to obtain the crude imidazolium ionic liquid; The solvent II is acetonitrile, and the mass of the solvent II is 200% of the sum of the mass of the imidazolium halide and the mass of the lithium salt of bis(trifluoromethanesulfonate) imide. The molar ratio of the imidazolium halide to the lithium salt of bis(trifluoromethanesulfonate) imide is 1:1.5, the temperature of the anion exchange reaction is 90℃, and the time is 60h.

[0046] (4) washing and drying the crude imidazolium ionic liquid to obtain the ionic liquid with low hydrogen solubility.

[0047] Comparative Example 1 A preparation method of the ionic liquid with low hydrogen solubility, the preparation method comprising the following steps: The difference from Example 2 is that: The halogenated alkane is selected from heptane.

[0048] Comparative Example 2 A preparation method of the ionic liquid with low hydrogen solubility, the preparation method comprising the following steps: The difference from Example 2 is that: The molar ratio of the imidazolium halide to the metal salt of bis(trifluoromethanesulfonate) imide is 1:1.6.

[0049] Comparative Example 3 A preparation method of the ionic liquid with low hydrogen solubility, the preparation method comprising the following steps: The difference from Example 2 is that: The molar ratio of the imidazolium halide to the metal salt of bis(trifluoromethanesulfonate) imide is 1:0.9. Example 4

[0050] A preparation method of the ionic liquid with low hydrogen solubility, the preparation method comprising the following steps: The difference from Example 2 is that: (4) washing and drying the crude imidazolium ionic liquid to obtain the imidazolium ionic liquid; (5) adding p-phenylenediamine and salicylaldehyde to the imidazolium ionic liquid, ultrasonic stirring for 15min, transferring to a high-pressure reaction kettle, reacting at 80℃ for 8h in a closed environment, naturally cooling to room temperature, and vacuum drying at 60℃ to constant weight to obtain the ionic liquid containing nanomaterials, i.e., the ionic liquid with low hydrogen solubility.

[0051] The mass ratio of the imidazolium ionic liquid, the p-phenylenediamine and the salicylaldehyde is 1:0.05:0.05.

[0052] Example 5 A preparation method of an ionic liquid with low hydrogen solubility, comprising the following steps: The difference from example 2 is that: (4) washing and drying the imidazole ionic liquid crude product to obtain the imidazole ionic liquid; (5) adding p-phenylenediamine and salicylaldehyde to the imidazole ionic liquid, ultrasonic stirring for 20 min, transferring to a high-pressure reaction kettle, reacting at 90 DEG C for 12 h in a closed environment, naturally cooling to room temperature, and vacuum drying at 70 DEG C to constant weight to obtain the ionic liquid containing nanomaterials, i.e. the ionic liquid with low hydrogen solubility.

[0053] The mass ratio of the imidazole ionic liquid, p-phenylenediamine and salicylaldehyde is 1:0.05:0.06.

[0054] Example 6 A preparation method of an ionic liquid with low hydrogen solubility, comprising the following steps: The difference from example 2 is that: (4) washing and drying the imidazole ionic liquid crude product to obtain the imidazole ionic liquid; (5) adding p-phenylenediamine and salicylaldehyde to the imidazole ionic liquid, ultrasonic stirring for 20 min, transferring to a high-pressure reaction kettle, reacting at 90 DEG C for 12 h in a closed environment, naturally cooling to room temperature, and vacuum drying at 70 DEG C to constant weight to obtain the ionic liquid containing nanomaterials, i.e. the ionic liquid with low hydrogen solubility.

[0055] The mass ratio of the imidazole ionic liquid, p-phenylenediamine and salicylaldehyde is 1:0.05:0.06.

[0056] Comparative example 4 A preparation method of an ionic liquid with low hydrogen solubility, comprising the following steps: The difference from example 5 is that: The mass ratio of the imidazole ionic liquid, p-phenylenediamine and salicylaldehyde is 1:0.05:0.09.

[0057] Comparative example 5 A preparation method of an ionic liquid with low hydrogen solubility, comprising the following steps: The difference from example 5 is that: The mass ratio of the imidazole ionic liquid, p-phenylenediamine and salicylaldehyde is 1:0.05:0.04.

[0058] Experimental example 1 The low hydrogen solubility ionic liquid was successfully synthesized by Examples 1-6, and the viscosity of the ionic liquid obtained by Examples 1-6, Comparative Examples 1-5 was tested, and the viscosity index was calculated, and each experiment was carried out at least 3 parallel tests, and the results are shown in Table 1. The test standard is: “Air compressor oil GB / T 12691-2021”.

[0059] Table 1

[0060] As can be seen from Table 1, the low hydrogen solubility ionic liquid provided by the application has stable kinematic viscosity at 40℃ and 100℃. Stable viscosity is the key for ionic liquid to play a good lubricating, cooling and sealing role in the compressor, which can ensure the normal operation of the compressor. Ionic liquid with too high viscosity is difficult to pass through the hose, valve and other accessories, which will cause loss of mechanical efficiency, and if the viscosity is too low, it will affect the compression efficiency of the hydrogen compressor. At the same time, the ionic liquid is repeatedly heated and cooled during the operation of the hydrogen compressor. As can be seen from Table 1, the application prepares nanomaterials in situ in the ionic liquid, which not only improves the viscosity of the ionic liquid, further improves the lubrication and sealing effect of the ionic liquid in the hydrogen compressor, but also makes the ionic liquid have good viscosity-temperature performance, ensuring that the ionic liquid can work stably and efficiently at each stage of hydrogen compression.

[0061] Experimental Example 2 The hydrogen solubility of the ionic liquid obtained by Examples 2, 5, Comparative Examples 1-5 was tested by using a GS type reaction kettle. Hydrogen was introduced into the reaction kettle which had been filled with low hydrogen solubility ionic liquid, and by controlling the temperature (25℃, 150℃) and pressure (5MPa, 10MPa, 15MPa, 20MPa), the pressure change in the system was detected to determine the solubility of hydrogen. Each experiment was carried out at least 3 parallel tests, and the results are shown in Table 2.

[0062] Table 2

[0063] As can be seen from Table 2, the ionic liquid with low hydrogen solubility provided by the application has low hydrogen solubility at a pressure of 5 MPa, 10 MPa, 15 MPa, and 20 MPa. Compared with Example 2, the nanoparticles are introduced into the structure of the ionic liquid by one-step reaction in Example 5, the obtained ionic liquid with low hydrogen solubility interacts with the internal structure of the nanomaterial, and the structure is more stable. The nanomaterial fills part of the free volume in the ionic liquid, and at the same time, its specific surface area can also change the transfer path and dissolution behavior of hydrogen in the ionic liquid, which can further reduce the solubility of hydrogen in the ionic liquid, thereby ensuring that the ionic liquid can replace the piston to directly contact hydrogen for hydrogen compression, and the hydrogen will not be contaminated in the compression process, thereby improving the stability and high efficiency of the ionic compressor in the long-period operation process.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A method for preparing an ionic liquid with low hydrogen solubility, characterized in that, The preparation method includes the following steps: (1) N-methylimidazolium, haloalkane and solvent are mixed and cooled in an ice bath to carry out N-alkylation reaction to obtain a mixture of alkylimidazolium halide; (2) The solvent 1 of the alkylimidazolium halide mixture is removed by vacuum distillation and then dried under vacuum to obtain the intermediate product alkylimidazolium halide; (3) The alkyl imidazole halide is mixed with bis(trifluoromethanesulfonic acid) imine metal salt and solvent II to carry out anion exchange reaction to obtain crude imidazole ionic liquid; (4) The crude imidazole ionic liquid is washed and dried to obtain an ionic liquid with low hydrogen solubility.

2. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The halogen in the haloalkane is one of fluorine, chlorine, and bromine, and the alkane in the haloalkane is one of methane, ethane, propane, butane, pentane, hexane, heptane, octane, and cyclohexane. The solvent is one or more of acetonitrile, acetone, butanone, petroleum ether, and ethyl acetate.

3. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The molar ratio of the haloalkane to the N-methylimidazole is 1:1 to 1:1.5, and the mass of the first solvent is 20-200% of the sum of the masses of the haloalkane and the N-methylimidazole.

4. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The N-alkylation reaction is carried out at a temperature of 20-90℃ for 2-24 hours.

5. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The molar ratio of the imidazolium halide to the bis(trifluoromethanesulfonic acid) imine metal salt is 1:1 to 1:1.

5.

6. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The bis(trifluoromethanesulfonic acid)imine metal salt is a lithium bis(trifluoromethanesulfonic acid)imine salt and / or a zinc bis(trifluoromethanesulfonic acid)imine salt.

7. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The second solvent is one or more of acetonitrile, acetone, butanone, petroleum ether, and ethyl acetate; the mass of the second solvent is 40-200% of the sum of the masses of the imidazolium halide and the bis(trifluoromethanesulfonic acid)imine metal salt.

8. The method for preparing an ionic liquid with low hydrogen solubility according to claim 1, characterized in that, The anion exchange reaction is carried out at a temperature of 20-90℃ for a time of 10-60h.

9. An ionic liquid with low hydrogen solubility, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of an ionic liquid with low hydrogen solubility as described in claim 9 above in the field of hydrogen compressor technology.

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