A complex ionic liquid, a preparation method and application thereof

Abstract

The application discloses a kind of complex ionic liquid, its preparation method and application, belong to ionic liquid preparation technical field.The complex ionic liquid of the application is by tetrafluoroborate ionic liquid, bis (trifluoromethyl sulfonyl) imine salt ionic liquid and tri (perfluoroalkyl) trifluorophosphate ionic liquid is formed by compounding.The complex ionic liquid viscosity is suitable, condensation point is low, and lubricating performance is superior, and corrosion resistance is strong, and thermal stability is good, and hydrophobicity is strong.Due to stable property, its service life is long, can satisfy as ionic liquid type hydrogen compressor liquid piston and lubricant requirement, after experiencing the huge temperature change of compression and expansion, property can still maintain stable, can replace traditional friction-reducing and anti-wear lubricant to adapt to harsh friction working environment.

Description

Technical Field

[0001] This invention belongs to the field of ionic liquid preparation technology, specifically relating to a compound ionic liquid, its preparation method and application. Background Technology

[0002] Currently, commonly used high-performance liquid lubricants mainly include perfluoropolyethers and phosphononitriles. However, perfluoropolyethers have poor boundary lubrication capabilities, are expensive, and are prone to corrosion and degradation at high temperatures. They also have poor solubility and compatibility with traditional additives. Phosphononitriles have good high-temperature lubrication capabilities, but their high-temperature volatility and low-temperature fluidity still need further improvement. Furthermore, traditional friction-reducing and anti-wear lubricants often contain heavy metals, sulfur, phosphorus, and other environmentally harmful elements, which greatly limits their further application in the field of lubricant additives. Therefore, further development of high-performance liquid lubricants to replace traditional friction-reducing and anti-wear lubricants is of great significance.

[0003] Ionic liquids (ILs) are molten salts composed of cations and anions that are liquid at or near room temperature. Typically, the cations are larger, with long alkyl chains and asymmetric molecular structures. Ionic liquids are an important component of high-performance lubricants. Their unique physical properties, such as non-flammability, low volatility, low melting point, outstanding thermal oxidation stability, and dipole structure, are required in lubrication and corrosion protection applications, attracting widespread attention in various fields. Furthermore, they contain active elements such as nitrogen, phosphorus, phosphorus, and phosphorus, which can potentially react with metals during friction to form anti-wear compounds. These properties are essential for ideal high-performance lubricant additives. ILs have gained widespread attention due to their stability, flexibility in molecular design, ease of synthesis, and adaptability to various functions. To date, more than 400 ILs have been tested as lubricants for different sliding pairs, exhibiting superior tribological properties in variable sliding pairs compared to mineral and synthetic lubricants. The physicochemical properties of ionic liquids can be easily altered by changing the structure of the constituent ions, particularly the types of cations and anions and the length of their alkyl chains. Up to 10¹⁸ anion-cation pairs can be generated through the combination of anions and cations. By altering these anion-cation pairs, the physical properties of ILs, such as melting point, density, viscosity, thermal stability, and hydrophobicity, can be tuned to meet the requirements of specific lubrication processes. The flexibility of their molecular design also makes the functionalization of ILs easy. For example, many researchers incorporate functional groups into the cations or anions of ILs to obtain "mission-specific" ILs that meet the application requirements under demanding engineering conditions.

[0004] However, when ionic liquids are used as lubricants, there are still problems such as poor compatibility, high pour point, poor stability, insufficient lubrication performance, and corrosiveness to the substrate. These defects greatly limit the application of ionic liquids in the field of lubricants. Summary of the Invention

[0005] This invention provides a compound ionic liquid, which is composed of tetrafluoroborate ionic liquid, bis(trifluoromethanesulfonyl)imine salt ionic liquid, and tri(perfluoroalkyl)trifluorophosphate ionic liquid. This compound ionic liquid has a low freezing point, good lubrication performance, strong corrosion resistance, low saturated vapor pressure, and strong thermal stability, and can replace traditional friction-reducing and anti-wear lubricants.

[0006] The technical solution of the present invention is as follows:

[0007] This invention provides a method for preparing a compound ionic liquid, comprising the following steps:

[0008] Tetrafluoroborate ionic liquid, bis(trifluoromethylsulfonyl)imine ionic liquid and tri(perfluoroalkyl)trifluorophosphate ionic liquid are mixed in proportion, stirred at 60-80℃ for 8-10 h, then sonicated for 1-2 h, and then vortexed for 1-2 h to obtain a compound ionic liquid.

[0009] The above-mentioned ionic liquids are all composed of cations and anions.

[0010] In this invention, the cation in the ionic liquid is selected from any one of the following cation salts: imidazole salt, quaternary ammonium salt, pyridine salt, thiazole salt, pyrrole salt; the anion is tetrafluoroborate, bis(trifluoromethylsulfonyl)imine salt, and tri(perfluoroalkyl)trifluorophosphate.

[0011] In this invention, the tetrafluoroborate ionic liquid can be specifically selected from any of the following: 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, hexyltripropylammonium tetrafluoroborate, and octyltriethylammonium tetrafluoroborate.

[0012] In this invention, the bis(trifluoromethanesulfonyl)imine salt ionic liquid can be specifically selected from any of the following: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, octyltripentylammonium bis(trifluoromethanesulfonyl)imine salt, hexyltriethylammonium bis(trifluoromethanesulfonyl)imine salt, and 1-dodecylpyridine bis(trifluoromethanesulfonyl)imine salt.

[0013] In this invention, the tri(perfluoroalkyl)trifluorophosphate ionic liquid can be specifically selected from any of the following: 1-hexyl-3-methylimidazolium tri(pentafluoroethyl)trifluorophosphate, 1-butylpyrrole tri(pentafluoroethyl)trifluorophosphate, 1-octylpyrrole tri(pentafluoroethyl)trifluorophosphate, 1-decylpyrrole tri(pentafluoroethyl)trifluorophosphate, hexyltripentylammonium (pentafluoroethyl)trifluorophosphate, hexyltributylammonium (pentafluoroethyl)trifluorophosphate, tripropyldecylammonium (pentafluoroethyl)trifluorophosphate, and 1-octyl-5-butylthiazole tri(pentafluoroethyl)trifluorophosphate.

[0014] In the above-mentioned method for preparing compound ionic liquids, the molar ratio of the tetrafluoroborate ionic liquid, the bis(trifluoromethylsulfonyl)imine salt ionic liquid, and the tri(pentafluoroethyl)trifluorophosphate ionic liquid is selected from 0 to 1:3 to 5:7 to 8.

[0015] In this invention, the preparation methods of tetrafluoroborate ionic liquids, bis(trifluoromethylsulfonyl)imine salt ionic liquids, and tri(perfluoroalkyl)trifluorophosphate type ionic liquids are as follows:

[0016] (1) Preparation of brine salts

[0017] A haloalkane and a nitrogen source are mixed at a molar ratio of 1.2–1.5:1, solvent A is added, and the mixture is heated to 80–120 °C and refluxed for 12–48 h. After cooling to room temperature, the solid is completely precipitated, and the liquid is removed to obtain a crude white crystalline halide. The crude halide is then added to solvent B at a molar ratio of 1:1–3, recrystallized at 40–60 °C, filtered, and the product is vacuum dried at 120–140 °C for 3–4 h to obtain the halide.

[0018] (2) Preparation of ionic liquids

[0019] Dissolve the halide salt in water at a mass ratio of 1:3 to 5 to obtain a halide salt solution; dissolve an anionic salt in water at a mass ratio of 1:1.5 to 3 with an equimolar amount of the halide salt to obtain an anionic salt solution; under stirring conditions at 50 to 90°C, slowly add the anionic salt solution dropwise to the halide salt solution; after the reaction is complete, allow the liquid to stand and separate into layers, separate the lower layer of ionic liquid, wash with deionized water until no halide ions are present, and vacuum dry at 120 to 140°C for 3 to 4 hours to obtain the ionic liquid.

[0020] In this invention, the haloalkane is selected from any one of the following: n-butane chloro, n-hexane bromo, n-octane bromo, n-heptane bromo, and n-dodecane bromo.

[0021] In this invention, the nitrogen source is selected from any one of the following: N-methylimidazole, pyridine, thiazole, pyrrole, triethylamine, tripropylamine, tributylamine, and tripentamine.

[0022] In this invention, solvent A is selected from any one of the following: n-propanol, isopropanol, glycerol, or allyl alcohol. If n-propanol and isopropanol are used, their amount is 20-40% of the total mass of the haloalkanes and nitrogen source; if glycerol and allyl alcohol are used, their amount is 30-50% of the total mass of the haloalkanes and nitrogen source.

[0023] In this invention, solvent B is selected from any one of the following: petroleum ether, ethyl acetate, toluene, xylene, and acetone.

[0024] In this invention, the anionic salt is tetrafluoroborate, bis(trifluoromethanesulfonyl)imine, or tri(perfluoroalkyl)trifluorophosphate. When preparing a tetrafluoroborate ionic liquid, the anionic salt is tetrafluoroborate; when preparing a bis(trifluoromethanesulfonyl)imine ionic liquid, the anionic salt is bis(trifluoromethanesulfonyl)imine; and when preparing a tri(perfluoroalkyl)trifluorophosphate ionic liquid, the anionic salt is tri(perfluoroalkyl)trifluorophosphate.

[0025] This invention provides a compound ionic liquid prepared by the above method.

[0026] This invention provides the application of the above-mentioned compound ionic liquid in friction reduction and wear resistance.

[0027] This invention provides the application of the above-mentioned compound ionic liquid in the preparation of friction-reducing and anti-wear lubricants.

[0028] The present invention provides a friction-reducing and wear-resistant lubricant, wherein the lubricant contains the above-mentioned compound ionic liquid.

[0029] The beneficial effects of this invention are as follows:

[0030] The compound ionic liquid of this invention has suitable viscosity, low freezing point, excellent lubrication performance, strong corrosion resistance, good thermal stability, and strong hydrophobicity. Due to its stable properties, it has a long service life and can meet the requirements of being used as a liquid piston and lubricant in ionic liquid hydrogen compressors. Its properties remain stable even after experiencing huge temperature changes due to compression and expansion, and it can replace traditional friction-reducing and anti-wear lubricants to adapt to harsh friction working environments. Attached Figure Description

[0031] Figure 1 The wear volume of the steel block sample on the steel / steel friction pair is represented by lubricant PAO10 and the composite ionic liquid described in Examples 1-8; wherein, from left to right, they are lubricant PAO10 and the composite ionic liquid described in Examples 1-8;

[0032] Figure 2 Polarization curves for lubricant PAO10, the composite ionic liquids described in Examples 1 and 3;

[0033] Figure 3 For the comparison of corrosion of each copper block sample, A is the lubricant PAO10, B is the composite ionic liquid described in Example 2, C is the composite ionic liquid described in Example 5, and D is the composite ionic liquid described in Example 6. Detailed Implementation

[0034] Other materials used in this invention, unless otherwise stated, are commercially available. Other terms used in this invention, unless otherwise specified, generally have the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and not intended to limit the scope of the invention in any way.

[0035] Example 1

[0036] The steps for preparing composite ionic liquids are as follows:

[0037] The composite ionic liquid in this embodiment is composed of 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt, and 1-hexyl-3-methylimidazolium tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 1:3:7.

[0038] 1. Preparation of brine salts

[0039] (1) 1-Hexyl-3-methylimidazolium bromide

[0040] 24.76 g of n-hexane bromide and 8.21 g of N-methylimidazole (molar ratio 1.5:1) were added to a flask, followed by 6.60 g of n-propanol (20% of the total mass of n-hexane bromide and N-methylimidazole). The mixture was heated to 120 °C with stirring under reflux for 12 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 24.72 g of the crude halide was added to 26.43 g of ethyl acetate (molar ratio 1:3), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 140 °C for 3 h to obtain 1-hexyl-3-methylimidazole bromide.

[0041] (2) 1-Butyl-3-methylimidazolium chloride

[0042] 11.11 g of n-butane chloride and 8.21 g of N-methylimidazolium (molar ratio 1.2:1) were added to a flask, followed by 7.73 g of isopropanol (40% of the total mass of n-butane chloride and N-methylimidazolium). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 18.74 g of the crude halide was added to 11.2 g of petroleum ether (molar ratio 1:1), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain 1-butyl-3-methylimidazolium chloride.

[0043] 2. Preparation of ionic liquids

[0044] (1) 1-Hexyl-3-methylimidazolium tetrafluoroborate ionic liquid

[0045] 24.72 g of 1-hexyl-3-methylimidazolium bromide was dissolved in 74.16 g of water (mass ratio 1:3) to obtain a 1-hexyl-3-methylimidazolium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with 1-hexyl-3-methylimidazolium bromide) was dissolved in 18.74 g of water (mass ratio 1:2) to obtain a lithium tetrafluoroborate solution; the lithium tetrafluoroborate solution was slowly added dropwise to the 1-hexyl-3-methylimidazolium bromide solution under heating and stirring at 50 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 3 h to obtain the 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0046] (2) 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0047] 17.47 g of 1-butyl-3-methylimidazolium chloride was dissolved in 69.88 g of water (mass ratio 1:4) to obtain a 1-butyl-3-methylimidazolium chloride solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imide (equimolar amount with 1-butyl-3-methylimidazolium chloride) was dissolved in 42.18 g of water (mass ratio 1:1.5) to obtain a bis(trifluoromethanesulfonyl)imide solution; the bis(trifluoromethanesulfonyl)imide solution was slowly added dropwise to the 1-butyl-3-methylimidazolium chloride solution under heating and stirring at 60 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid.

[0048] (3) 1-Hexyl-3-methylimidazolium tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0049] 24.72 g of 1-hexyl-3-methylimidazolium bromide was dissolved in 74.16 g of water (mass ratio 1:3) to obtain a 1-hexyl-3-methylimidazolium bromide solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with 1-hexyl-3-methylimidazolium bromide) was dissolved in 70.20 g of water (mass ratio 1:1.5) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the 1-hexyl-3-methylimidazolium bromide solution under heating and stirring at 80 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0050] 3. Compound

[0051] 25.41 g of 1-hexyl-3-methylimidazolium tetrafluoroborate ionic liquid, 119.21 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid, and 428.58 g of 1-hexyl-3-methylimidazolium tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:3:7), stirred at 80 °C for 8 h, then sonicated for 2 h, and then mixed with a vortex mixer for 1 h to obtain a compound ionic liquid.

[0052] The compound ionic liquid was measured to have a freezing point of -64℃, a thermal decomposition temperature of 471℃, and a viscosity of 12.84 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 44Pa, and the water content of the ionic liquid at 25℃ is 78ppm.

[0053] Example 2

[0054] The steps for preparing composite ionic liquids are as follows:

[0055] The composite ionic liquid in this embodiment is composed of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt and decyltripropylammonium tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 3:8.

[0056] 1. Preparation of brine salts

[0057] (1) 1-Octyl-3-methylimidazolium bromide

[0058] 25.11 g of n-octane bromide and 8.21 g of N-methylimidazole (molar ratio 1.3:1) were added to a flask, followed by 7.44 g of n-propanol (20% of the total mass of n-octane bromide and N-methylimidazole). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 36.82 g of the crude halide was added to 11.68 g of toluene (molar ratio 1:1.1), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain 1-octyl-3-methylimidazole bromide.

[0059] (2) Decyltripropylammonium salt

[0060] 31.48 g of decane bromide and 14.33 g of tripropylamine (molar ratio 1.4:1) were added to a flask, followed by 18.32 g of isopropanol (40% of the total mass of decane bromide and tripropylamine). The mixture was heated to 100 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 35.73 g of the crude halide was added to 10.17 g of xylene (molar ratio 1:1), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 130 °C for 3 h to obtain decyltripropylammonium salt.

[0061] 2. Preparation of ionic liquids

[0062] (1) 1-Octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0063] 27.52 g of 1-octyl-3-methylimidazolium bromide was dissolved in 82.56 g of water (mass ratio 1:3) to obtain a 1-octyl-3-methylimidazolium bromide solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imine (equimolar amount with 1-octyl-3-methylimidazolium bromide) was dissolved in 56.24 g of water (mass ratio 1:2) to obtain a bis(trifluoromethanesulfonyl)imine solution; the bis(trifluoromethanesulfonyl)imine solution was slowly added dropwise to the 1-octyl-3-methylimidazolium bromide solution under heating and stirring at 80 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 4 h to obtain the 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine ionic liquid.

[0064] (2) Decyltripropylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0065] 36.43 g of decyltripropylammonium salt was dissolved in 145.72 g of water (mass ratio 1:4) to obtain a decyltripropylammonium salt solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with decyltripropylammonium salt) was dissolved in 70.2 g of water (mass ratio 1:1.5) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the decyltripropylammonium salt solution under heating and stirring at 80 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 140 °C for 3 h to obtain the decyltripropylammonium tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0066] 3. Compound

[0067] 55.31g of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid and 218.67g of decyltripropylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 3:8), stirred at 70℃ for 8h, then sonicated for 2h, and then mixed with a vortex mixer for 2h to obtain a compound ionic liquid.

[0068] The mixed ionic liquid was measured to have a freezing point of -76℃, a thermal decomposition temperature of 493℃, and a viscosity of 13.63 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 68Pa, and the water content of the ionic liquid at 25℃ is 44ppm.

[0069] Example 3

[0070] The steps for preparing composite ionic liquids are as follows:

[0071] The composite ionic liquid in this embodiment is composed of octyltripropylammonium tetrafluoroborate, hexyltriethylammonium bis(trifluoromethanesulfonyl)imine salt, and hexyltributylammonium tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 1:5:8.

[0072] 1. Preparation of brine salts

[0073] (1) Octyltripropylammonium salt

[0074] 21.49 g of n-octane bromide and 14.33 g of tripropylamine (molar ratio 1.2:1) were added to a flask, followed by 7.16 g of n-propanol (20% of the total mass of n-octane bromide and tripropylamine). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 32.24 g of the crude halide was added to 9.21 g of toluene (molar ratio 1:1), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain octyltripropylammonium bromide.

[0075] (2) Hexyltriethylammonium salt

[0076] 20.63 g of n-hexane bromide and 10.12 g of triethylamine (molar ratio 1.25:1) were added to a flask, followed by 9.23 g of glycerol (30% of the total mass of n-hexane bromide and triethylamine). The mixture was heated to 100 °C with stirring under reflux for 36 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 26.62 g of the crude halide was added to 12.74 g of xylene (molar ratio 1:1.2), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain hexyltriethylammonium bromide.

[0077] (3) Hexyltributylammonium salt

[0078] 23.11 g of n-hexane bromide and 18.53 g of tributylamine (molar ratio 1.4:1) were added to a flask, followed by 20.82 g of isopropanol (50% of the total mass of n-hexane bromide and tributylamine). The mixture was heated to 120 °C with stirring under reflux for 36 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 35.04 g of the crude halide was added to 8.71 g of acetone (molar ratio 1:1.5), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain hexyltributylammonium bromide.

[0079] 2. Preparation of ionic liquids

[0080] (1) Octyltripropylammonium tetrafluoroborate ionic liquid

[0081] 32.24 g of octyltripropylammonium bromide was dissolved in 96.72 g of water (mass ratio 1:3) to obtain an octyltripropylammonium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with octyltripropylammonium bromide) was dissolved in 18.74 g of water (mass ratio 1:2) to obtain a tetrafluoroborate solution; the tetrafluoroborate solution was slowly added dropwise to the octyltripropylammonium bromide solution under heating and stirring at 50 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 3 h to obtain the octyltripropylammonium tetrafluoroborate ionic liquid.

[0082] (2) Hexyltriethylammonium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0083] 26.62 g of hexyltriethylammonium bromide was dissolved in 79.86 g of water (mass ratio 1:3) to obtain a hexyltriethylammonium bromide solution; 46.80 g of sodium bis(trifluoromethanesulfonyl)imine (equimolar amount with hexyltriethylammonium bromide) was dissolved in 70.20 g of water (mass ratio 1:1.5) to obtain a bis(trifluoromethanesulfonyl)imine salt solution; the bis(trifluoromethanesulfonyl)imine salt solution was slowly added dropwise to the hexyltriethylammonium bromide solution under heating and stirring at 70 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 140 °C for 4 h to obtain the hexyltriethylammonium bis(trifluoromethanesulfonyl)imine salt ionic liquid.

[0084] (3) Hexyltributylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0085] 35.04 g of hexyltributylammonium bromide was dissolved in 175.2 g of water (mass ratio 1:5) to obtain a hexyltributylammonium bromide solution; 44.50 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with hexyltributylammonium bromide) was dissolved in 66.75 g of water (mass ratio 1:1.5) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the hexyltributylammonium bromide solution under heating and stirring at 80 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 140 °C for 4 h to obtain the hexyltributylammonium tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0086] 3. Compound

[0087] 31.23 g of octyltripropylammonium tetrafluoroborate ionic liquid, 215.65 g of hexyltriethylammonium bis(trifluoromethanesulfonyl)imine ionic liquid, and 554.13 g of hexyltributylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:5:8), stirred at 60 °C for 10 h, then sonicated for 1.5 h, and then mixed with a vortex mixer for 2 h to obtain a compound ionic liquid.

[0088] The mixed ionic liquid was measured to have a freezing point of -72℃, a thermal decomposition temperature of 513℃, and a viscosity of 14.72 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 61Pa, and the water content of the ionic liquid at 25℃ is 62ppm.

[0089] Example 4

[0090] The steps for preparing composite ionic liquids are as follows:

[0091] The composite ionic liquid in this embodiment is composed of 1-dodecylpyridine bis(trifluoromethanesulfonyl)imine salt and 1-octyl-5-butylthiazole tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 4:7.

[0092] 1. Preparation of brine salts

[0093] (1) 1-Dodecylpyridine bromide

[0094] 47.22 g of n-dodecane bromide and 6.71 g of pyridine (molar ratio 1.2:1) were added to a flask, followed by 10.79 g of n-propanol (20% of the total mass of n-dodecane bromide and pyridine). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 46.06 g of the crude halide was added to 10.57 g of ethyl acetate (molar ratio 1:1.2), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 140 °C for 3 h to obtain 1-dodecylpyridine bromide.

[0095] (2) 1-Octyl-5-butylthiazolyl bromide

[0096] 23.28 g of n-octane bromide and 14.12 g of butylthiazole (molar ratio 1.3:1) were added to a flask, followed by 13.09 g of isopropanol (35% of the total mass of n-octane bromide and butylthiazole). The mixture was heated to 90 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 32.03 g of the crude halide was added to 14.56 g of petroleum ether (molar ratio 1:1.3), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain 1-octyl-5-butylthiazole bromide.

[0097] 2. Preparation of ionic liquids

[0098] (1) 1-Dodecylpyridinebis(trifluoromethylsulfonyl)imine salt ionic liquid

[0099] 46.06 g of 1-dodecylpyridine bromide was dissolved in 138.18 g of water (mass ratio 1:3) to obtain an aqueous solution of 1-dodecylpyridine bromide; 46.80 g of sodium bis(trifluoromethanesulfonyl)imine (equimolar amount with 1-dodecylpyridine bromide) was dissolved in 70.20 g of water (mass ratio 1:1.5) to obtain a bis(trifluoromethanesulfonyl)imine solution; the bis(trifluoromethanesulfonyl)imine solution was slowly added dropwise to the 1-dodecylpyridine bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 4 h to obtain the 1-dodecylpyridine bis(trifluoromethanesulfonyl)imine ionic liquid.

[0100] (2) 1-Octyl-5-butylthiazole tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0101] 32.03 g of 1-octyl-5-butylthiazolium bromide was dissolved in 160.15 g of water (mass ratio 1:5) to obtain a 1-octyl-5-butylthiazolium bromide solution; 44.50 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with 1-octyl-5-butylthiazolium bromide) was dissolved in 88.90 g of water (mass ratio 1:2) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the 1-octyl-5-butylthiazolium bromide solution under heating and stirring at 70 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 130 °C for 4 h to obtain the 1-octyl-5-butylthiazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0102] 3. Compound

[0103] 92.14 g of 1-dodecylpyridine bis(trifluoromethanesulfonyl)imine ionic liquid and 132.08 g of 1-octyl-5-butylthiazolium tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 4:7), stirred at 80 °C for 8 h, then sonicated for 1 h, and then mixed with a vortex mixer for 1 h to obtain a compound ionic liquid.

[0104] The compound ionic liquid was measured to have a freezing point of 80℃, a thermal decomposition temperature of 521℃, a viscosity of 12.73 mm² / s at 100℃, a vapor pressure of 42 Pa at 200℃, and a water content of 66 ppm at 25℃.

[0105] Example 5

[0106] The steps for preparing composite ionic liquids are as follows:

[0107] The composite ionic liquid in this embodiment is composed of 1-octyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt and 1-butylpyrrole tri(pentafluoroethyl) trifluorophosphate in a molar ratio of 1:3:8.

[0108] 1. Preparation of brine salts

[0109] (1) 1-Octyl-3-methylimidazolium bromide

[0110] See Example 2 for details on the preparation of halide salts.

[0111] (2) 1-Hexyl-3-methylimidazolium bromide

[0112] See Example 1 for details on the preparation of halide salts.

[0113] (3) 1-Butylpyrrole chloride

[0114] 13.88 g of n-butane chloride and 6.71 g of pyrrole (molar ratio 1.5:1) were added to a flask, followed by 8.24 g of glycerol (40% of the total mass of n-butane chloride and pyrrole). The mixture was heated to 120 °C with stirring under reflux for 24 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 15.96 g of the crude halide was added to 20.42 g of acetone (molar ratio 1:3), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 60 °C for 4 h to obtain 1-butylpyrrole chloride.

[0115] 2. Preparation of ionic liquids

[0116] (1) 1-Octyl-3-methylimidazolium tetrafluoroborate ionic liquid

[0117] 25.72 g of 1-octyl-3-methylimidazolium bromide was dissolved in 75.16 g of water (mass ratio 1:3) to obtain a 1-octyl-3-methylimidazolium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with 1-octyl-3-methylimidazolium bromide) was dissolved in 28.11 g of water (mass ratio 1:3) to obtain a lithium tetrafluoroborate solution; the lithium tetrafluoroborate solution was slowly added dropwise to the 1-octyl-3-methylimidazolium bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 4 h to obtain the 1-octyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0118] (2) 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0119] 18.62 g of 1-hexyl-3-methylimidazolium bromide was dissolved in 93.10 g of water (mass ratio 1:5) to obtain a 1-hexyl-3-methylimidazolium bromide solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imide (equimolar amount with 1-hexyl-3-methylimidazolium bromide) was dissolved in 56.24 g of water (mass ratio 1:2) to obtain a bis(trifluoromethanesulfonyl)imide solution; the bis(trifluoromethanesulfonyl)imide solution was slowly added dropwise to the 1-hexyl-3-methylimidazolium bromide solution under heating and stirring at 70 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid.

[0120] (3) 1-Butylpyrrole tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0121] 13.88 g of 1-butylpyrrole chloride was dissolved in 69.40 g of water (mass ratio 1:5) to obtain a 1-butylpyrrole chloride solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with 1-butylpyrrole chloride) was dissolved in 93.60 g of water (mass ratio 1:2) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the 1-butylpyrrole chloride solution under heating and stirring at 70 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-butylpyrrole tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0122] 3. Compound

[0123] 35.09 g of 1-octyl-3-methylimidazolium tetrafluoroborate ionic liquid, 140.22 g of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid, and 485.44 g of 1-butylpyrrole tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:3:8), stirred at 60 °C for 10 h, then sonicated for 1.5 h, and then mixed with a vortex mixer for 2 h to obtain a compound ionic liquid.

[0124] The compound ionic liquid was measured to have a freezing point of -78℃, a thermal decomposition temperature of 498℃, and a viscosity of 13.46 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 64Pa, and the water content of the ionic liquid at 25℃ is 43ppm.

[0125] Example 6

[0126] The steps for preparing composite ionic liquids are as follows:

[0127] The composite ionic liquid in this embodiment is composed of 1-decyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt and 1-octylpyrrole tri(pentafluoroethyl) trifluorophosphate in a molar ratio of 1:4:8.

[0128] 1. Preparation of brine salts

[0129] (1) 1-decyl-3-methylimidazolium bromide

[0130] 22.90 g of decane bromide and 8.21 g of N-methylimidazole (molar ratio 1.2:1) were added to a flask, followed by 6.22 g of n-propanol (20% of the total mass of decane bromide and N-methylimidazole). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 27.29 g of the crude halide was added to 13.44 g of petroleum ether (molar ratio 1:1.2), recrystallized at 50 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain 1-decyl-3-methylimidazole bromide.

[0131] (2) 1-Octyl-3-methylimidazolium bromide

[0132] See Example 2 for details on the preparation of halide salts.

[0133] (3) 1-Octylpyrrole bromide

[0134] 19.31 g of n-octane bromide and 6.71 g of pyrrole (molar ratio 1.3:1) were added to a flask, followed by 10.41 g of glycerol (40% of the total mass of n-octane bromide and pyrrole). The mixture was heated to 110 °C with stirring under reflux for 24 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 21.56 g of the crude halide was added to 21.23 g of xylene (molar ratio 1:2), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 140 °C for 4 h to obtain 1-octylpyrrole bromide.

[0135] 2. Preparation of ionic liquids

[0136] (1) 1-decyl-3-methylimidazolium tetrafluoroborate ionic liquid

[0137] 27.29 g of 1-decyl-3-methylimidazolium bromide was dissolved in 81.87 g of water (mass ratio 1:3) to obtain a 1-decyl-3-methylimidazolium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with 1-decyl-3-methylimidazolium bromide) was dissolved in 14.05 g of water (mass ratio 1:1.5) to obtain a lithium tetrafluoroborate solution; the lithium tetrafluoroborate solution was slowly added dropwise to the 1-decyl-3-methylimidazolium bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 3 h to obtain the 1-decyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0138] (2) 1-Octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0139] 18.76 g of 1-octyl-3-methylimidazolium bromide was dissolved in 93.80 g of water (mass ratio 1:5) to obtain a 1-octyl-3-methylimidazolium bromide solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imide (equimolar amount with 1-octyl-3-methylimidazolium bromide) was dissolved in 56.24 g of water (mass ratio 1:2) to obtain a bis(trifluoromethanesulfonyl)imide solution; the bis(trifluoromethanesulfonyl)imide solution was slowly added dropwise to the 1-octyl-3-methylimidazolium bromide solution under heating and stirring at 70 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 130 °C for 3 h to obtain the 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid.

[0140] (3) 1-Octylpyrrole tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0141] 21.56 g of 1-octylpyrrole bromide was dissolved in 64.68 g of water (mass ratio 1:3) to obtain a 1-octylpyrrole bromide solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with 1-octylpyrrole bromide) was dissolved in 93.60 g of water (mass ratio 1:2) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the 1-octylpyrrole bromide solution under heating and stirring at 90 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-octylpyrrole tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0142] 3. Compound

[0143] 36.66 g of 1-decyl-3-methylimidazolium tetrafluoroborate ionic liquid, 187.52 g of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid, and 546.88 g of 1-octylpyrrole tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:4:8), stirred at 80 °C for 8 h, then sonicated for 1 h, and then mixed with a vortex mixer for 2 h to obtain a compound ionic liquid.

[0144] The mixed ionic liquid was measured to have a freezing point of -75℃, a thermal decomposition temperature of 482℃, and a viscosity of 11.98 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 87Pa, and the water content of the ionic liquid at 25℃ is 90ppm.

[0145] Example 7

[0146] The steps for preparing composite ionic liquids are as follows:

[0147] The composite ionic liquid in this embodiment is composed of hexyltripropylammonium tetrafluoroborate, 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt and 1-decylpyrrole tri(pentafluoroethyl) trifluorophosphate in a molar ratio of 1:4:7.

[0148] 1. Preparation of brine salts

[0149] (1) Hexyltripropylammonium bromide

[0150] 20.63 g of n-hexane bromide and 14.32 g of tripropylamine (molar ratio 1.2:1) were added to a flask, followed by 6.99 g of n-propanol (20% of the total mass of n-hexane bromide and tripropylamine). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 31.51 g of the crude halide was added to 13.44 g of petroleum ether (molar ratio 1:1.2), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain hexyltripropylammonium bromide.

[0151] (2) 1-Dodecyl-3-methylimidazolium bromide

[0152] 47.22 g of n-dodecane bromide and 8.21 g of N-methylimidazole (molar ratio 1.2:1) were added to a flask, followed by 16.63 g of isopropanol (30% of the total mass of n-dodecane bromide and N-methylimidazole). The mixture was heated to 110 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 47.56 g of the crude halide was added to 11.45 g of ethyl acetate (molar ratio 1:1.3), recrystallized at 50 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain 1-dodecyl-3-methylimidazole bromide.

[0153] (3) 1-Ceylpyrrole bromide

[0154] 25.10 g of decane bromide and 6.71 g of pyrrole (molar ratio 1.3:1) were added to a flask, followed by 15.91 g of allyl alcohol (50% of the total mass of decane bromide and pyrrole). The mixture was heated to 110 °C with stirring under reflux for 36 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 26.02 g of the crude halide was added to 28.71 g of toluene (molar ratio 1:1.5), recrystallized at 60 °C, filtered, and the product was dried under vacuum at 140 °C for 3 h to obtain 1-decylpyrrole bromide.

[0155] 2. Preparation of ionic liquids

[0156] (1) Hexyltripropylammonium tetrafluoroborate ionic liquid

[0157] 31.51 g of hexyltripropylammonium bromide was dissolved in 94.53 g of water (mass ratio 1:3) to obtain a hexyltripropylammonium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with hexyltripropylammonium bromide) was dissolved in 14.05 g of water (mass ratio 1:1.5) to obtain a lithium tetrafluoroborate solution; the lithium tetrafluoroborate solution was slowly added dropwise to the hexyltripropylammonium bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 3 h to obtain the hexyltripropylammonium tetrafluoroborate ionic liquid.

[0158] (2) 1-Dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0159] 47.56 g of 1-dodecyl-3-methylimidazolium bromide was dissolved in 237.80 g of water (mass ratio 1:5) to obtain a 1-dodecyl-3-methylimidazolium bromide solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imide (equimolar amount with 1-dodecyl-3-methylimidazolium bromide) was dissolved in 56.24 g of water (mass ratio 1:2) to obtain a bis(trifluoromethanesulfonyl)imide solution; the bis(trifluoromethanesulfonyl)imide solution was slowly added dropwise to the 1-dodecyl-3-methylimidazolium bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 130 °C for 3 h to obtain the 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid.

[0160] (3) 1-Decylpyrroletri(pentafluoroethyl)trifluorophosphate ionic liquid

[0161] 26.02 g of 1-decylpyrrole bromide was dissolved in 130.10 g of water (mass ratio 1:5) to obtain a 1-decylpyrrole bromide solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with 1-decylpyrrole bromide) was dissolved in 70.20 g of water (mass ratio 1:1.5) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the 1-decylpyrrole bromide solution under heating and stirring at 90 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 140 °C for 4 h to obtain the 1-decylpyrrole tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0162] 3. Compound

[0163] 40.88 g of hexyltripropylammonium tetrafluoroborate ionic liquid, 302.72 g of 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid, and 509.74 g of 1-decylpyrrole tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:4:7), stirred at 70 °C for 10 h, then sonicated for 1.5 h, and then mixed with a vortex mixer for 1.5 h to obtain a compound ionic liquid.

[0164] The compound ionic liquid was measured to have a freezing point of -68℃, a thermal decomposition temperature of 502℃, and a viscosity of 13.44 mm at 100℃. 2 / s, the vapor pressure at 200℃ is 60Pa, and the water content of the ionic liquid at 25℃ is 73ppm.

[0165] Example 8

[0166] The steps for preparing composite ionic liquids are as follows:

[0167] The composite ionic liquid in this embodiment is composed of octyltriethylammonium tetrafluoroborate, octyltripentylammonium bis(trifluoromethanesulfonyl)imine salt and hexyltripentylammonium tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 1:3:8.

[0168] 1. Preparation of brine salts

[0169] (1) Octyltriethylammonium bromide

[0170] 25.11 g of n-octane bromide and 10.12 g of triethylamine (molar ratio 1.3:1) were added to a flask, followed by 7.05 g of n-propanol (20% of the total mass of n-octane bromide and triethylamine). The mixture was heated to 80 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 31.51 g of the crude halide was added to 7.21 g of toluene (molar ratio 1:1.2), recrystallized at 50 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain octyltriethylammonium bromide.

[0171] (2) Octyltripentylammonium bromide

[0172] 28.97 g of n-octane bromide and 22.74 g of tripentylamine (molar ratio 1.5:1) were added to a flask, followed by 15.51 g of isopropanol (30% of the total mass of n-octane bromide and tripentylamine). The mixture was heated to 110 °C with stirring under reflux for 48 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 42.05 g of the crude halide was added to 7.21 g of ethyl acetate (molar ratio 1:1.2), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain octyltripentylammonium bromide.

[0173] (3) Hexyltripentylammonium bromide

[0174] 22.35 g of n-hexane bromide and 22.74 g of tripentylamine (molar ratio 1.3:1) were added to a flask, followed by 18.04 g of allyl alcohol (40% of the total mass of n-hexane bromide and tripentylamine). The mixture was heated to 110 °C with stirring under reflux for 24 h, then cooled to room temperature until the solid completely precipitated. Excess liquid was removed by filtration to obtain a crude white crystalline halide. 42.05 g of the crude halide was added to 7.21 g of petroleum ether (molar ratio 1:1.2), recrystallized at 40 °C, filtered, and the product was dried under vacuum at 120 °C for 4 h to obtain hexyltripentylammonium bromide.

[0175] 2. Preparation of ionic liquids

[0176] (1) Octyltriethylammonium tetrafluoroborate ionic liquid

[0177] 31.51 g of octyltriethylammonium bromide was dissolved in 94.53 g of water (mass ratio 1:3) to obtain an octyltriethylammonium bromide solution; 9.37 g of lithium tetrafluoroborate (equimolar amount with octyltriethylammonium bromide) was dissolved in 14.05 g of water (mass ratio 1:1.5) to obtain a lithium tetrafluoroborate solution; the lithium tetrafluoroborate solution was slowly added dropwise to the octyltriethylammonium bromide solution under heating and stirring at 60 °C; after the reaction was complete, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halogen ions were present, and dried under vacuum at 120 °C for 3 h to obtain an octyltriethylammonium tetrafluoroborate ionic liquid.

[0178] (2) Octyltripentylammonium bis(trifluoromethylsulfonyl)imine salt ionic liquid

[0179] 42.05 g of octyltripentylammonium bromide was dissolved in 210.25 g of water (mass ratio 1:5) to obtain an octyltripentylammonium bromide solution; 28.12 g of sodium bis(trifluoromethanesulfonyl)imide (equimolar amount with octyltripentylammonium bromide) was dissolved in 42.18 g of water (mass ratio 1:1.5) to obtain a bis(trifluoromethanesulfonyl)imide solution; the bis(trifluoromethanesulfonyl)imide solution was slowly added dropwise to the octyltripentylammonium bromide solution under heating and stirring at 60 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 130 °C for 3 h to obtain the octyltripentylammonium bis(trifluoromethanesulfonyl)imide ionic liquid.

[0180] (3) Hexyltripentylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid

[0181] 42.05 g of hexyltripentylammonium bromide was dissolved in 210.25 g of water (mass ratio 1:5) to obtain a hexyltripentylammonium bromide solution; 46.80 g of sodium tris(pentafluoroethyl)trifluorophosphate (equimolar amount with hexyltripentylammonium bromide) was dissolved in 70.20 g of water (mass ratio 1:1.5) to obtain a tris(pentafluoroethyl)trifluorophosphate solution; the tris(pentafluoroethyl)trifluorophosphate solution was slowly added dropwise to the hexyltripentylammonium bromide solution under heating and stirring at 90 °C; after the reaction was completed, the liquid was transferred to a separatory funnel for static separation, the lower ionic liquid was separated, washed with deionized water until no halide ions were present, and dried under vacuum at 140 °C for 4 h to obtain the hexyltripentylammonium tris(pentafluoroethyl)trifluorophosphate ionic liquid.

[0182] 3. Compound

[0183] 40.88 g of octyltriethylammonium tetrafluoroborate ionic liquid, 210.51 g of octyltripentylammonium bis(trifluoromethanesulfonyl)imine ionic liquid, and 710.80 g of hexyltripentylammonium tri(pentafluoroethyl)trifluorophosphate ionic liquid were mixed (molar ratio 1:3:8), stirred at 80 °C for 9 h, then sonicated for 1.5 h, and then mixed with a vortex mixer for 2 h to obtain a compound ionic liquid.

[0184] The compound ionic liquid was measured to have a freezing point of -62℃, a thermal decomposition temperature of 483℃, and a viscosity of 11.49 mmHg at 100℃. 2 / s, the vapor pressure at 200℃ is 78Pa, and the water content of the ionic liquid at 25℃ is 48ppm.

[0185] Physical performance test

[0186] 1. Wear resistance

[0187] The anti-wear properties of the composite ionic liquids prepared in Examples 1-8 were determined using the lubricating oil anti-wear performance test method (four-ball machine method), and compared with those of PAO10, a commonly available lubricating oil on the market.

[0188] The test results are as follows Figure 1 As shown:

[0189] Depend on Figure 1 It can be seen that the wear amount of the compound ionic liquid prepared by this invention is significantly lower than that of PAO10 lubricating oil. This indicates that the compound ionic liquid of this invention has superior lubrication performance and strong anti-wear properties.

[0190] 2. Cyclic Voltammetry Test

[0191] The polarization curves of the lubricating oil PAO10 and the compound ionic liquid described in Examples 1 and 3 were determined by cyclic voltammetry.

[0192] The test results are as follows Figure 2 As shown:

[0193] Depend on Figure 2 It can be seen that the corrosion current density of Examples 1 and 3 is lower than that of lubricating oil PAO10, the corrosion potential of the ionic liquid is higher than that of lubricating oil PAO10, and the electrochemical window of the ionic liquid is wider than that of lubricating oil PAO10. This indicates that the composite ionic liquid prepared by the present invention has a low and stable corrosion rate on the material and exhibits excellent corrosion resistance.

[0194] 3. Copper strip corrosion test

[0195] The corrosion of the lubricating oil PAO10 and the compound ionic liquids described in Examples 2, 5, and 6 were determined using the copper strip corrosion test according to GB / T 6144-2010.

[0196] The test results are as follows Figure 3 As shown:

[0197] Depend on Figure 3 It can be seen that the surface color of the copper sheet corroded by the composite ionic liquid of the present invention does not change significantly, and the corrosion marks are also significantly less than those of the lubricating oil PAO10, indicating that the composite ionic liquid of the present invention has very little corrosiveness to the copper sheet.

[0198] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A compound ionic liquid, characterized in that, It is composed of octyltripropylammonium tetrafluoroborate, hexyltriethylammonium bis(trifluoromethanesulfonyl)imine salt, and hexyltributylammonium tri(pentafluoroethyl)trifluorophosphate in a molar ratio of 1:5:

8.

2. The application of the compound ionic liquid of claim 1 in friction reduction and wear resistance.

3. The application of the compound ionic liquid of claim 1 in the preparation of friction-reducing and anti-wear lubricants.

4. A friction-reducing and anti-wear lubricant, characterized in that, Contains the compound ionic liquid as described in claim 1.

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