A molybdate ionic liquid, a preparation method thereof, and its application in water-based lubricants

Abstract

The present invention discloses a molybdate ionic liquid, a preparation method thereof, and its application in water-based lubricants. A two-step method is used to synthesize N-alkyl imidazolate ionic liquids with different alkyl substitutions and different anions; the molybdate ionic liquid is prepared through an amidation reaction and a molybdenation reaction; and the synthesized molybdate ionic liquid is applied as an additive to a water-based lubricant, effectively improving the lubrication performance of the water-based lubricant and reducing its corrosiveness. The molybdate ionic liquid of the present invention has excellent solubility in water and high stability, can effectively improve the anti-wear and friction-reducing capabilities of the water-based lubricant, and also has a good effect on improving the corrosion of metal equipment. Furthermore, the structure and function of the ionic liquid can be specifically designed according to different needs, and has broad application prospects in the field of water-based lubricants.

Description

Technical Field

[0001] The present invention relates to the technical field of ionic liquid and organic molybdenum, and in particular to a molybdate ionic liquid and a preparation method thereof, and application of the molybdate ionic liquid as a water-based lubricating additive in lubrication. Background Art

[0002] Ionic liquids inherently possess advantages such as non-volatility, non-flammability, low vapor pressure, strong solubility, and a wide operating temperature range. They are highly designable, exhibit good thermal and chemical stability, are easily separated from other substances, and can be recycled. They have promising application prospects in various fields, including materials, electrochemistry, and extraction separation. A key characteristic of ionic liquids is their functional designability, which can be achieved by varying the type and composition of anions and cations. As room-temperature molten salts composed entirely of anions and cations, ionic liquids have attracted widespread attention due to their numerous excellent properties. To date, they have been widely used in chemical and chemical research fields, including catalysis, separation, and the synthesis of photoelectric conversion materials. Research on ionic liquids has made remarkable progress.

[0003] Organic molybdenum compound lubricating materials occupy a very important position among many lubricating materials due to their excellent tribological properties. As lubricating oil additives with both anti-friction, anti-wear and antioxidant properties, they can significantly improve the anti-wear and friction-reducing properties of lubricants, effectively reduce friction and wear on the friction pair surface, show good high-temperature antioxidant properties, and improve mechanical efficiency. They have been one of the hot topics in lubricating additive research at home and abroad in recent years.

[0004] Organic molybdenum ionic liquids prepared by combining ionic liquids with organic molybdenum have the advantages of both organic molybdenum and ionic liquids. They not only have the advantages of high vapor pressure, thermal stability, and low corrosion, but can also be used in lubricating additives, cellulose catalytic degradation, etc., and have been widely studied. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a molybdate ionic liquid prepared by combining an ionic liquid with an organic molybdenum, which has the advantages of both organic molybdenum and ionic liquid.

[0006] The technical solution adopted by the present invention is: a molybdate ionic liquid having the structural formula shown in (I),

[0007]

[0008] in,

[0009] R' is an ethyl molybdate ionic liquid;

[0010] X is selected from one of halogen, [N(CN)2]-, [NO2]-, [NO3]-, [H2PO4]-, [HSO4]-, [DCA]-, [EtSO4]-, [BF4]-, [PF6]-, [AlCl4]-, [ClO4]-, [FSI]-, [TFSI]-, [CF3CO2]-, and [OMs]-.

[0011] A method for preparing a molybdate ionic liquid comprises the following steps:

[0012] 1) reacting N-alkyl imidazole with methyl bromoacetate at 70-90° C. for 8-10 h, cooling to room temperature, washing, and rotary evaporation to remove the solvent and excess methyl bromoacetate to obtain a 1-alkyl-3-methyl imidazole bromide ionic liquid;

[0013] 2) Amidation reaction: 1-alkyl-3-acetic acid methyl imidazolium bromide ionic liquid is reacted with diethanolamine at 70-90°C for 14 hours, cooled to room temperature, extracted with an organic solvent, and the solvent is removed by rotary evaporation and dried in vacuo to obtain N-alkyl imidazole diethanolamide ionic liquid;

[0014] 3) Molybdenation reaction: Under nitrogen protection, N-alkyl imidazole diethanolamide ionic liquid and a molybdenum source are refluxed at 115-120°C for 3-4 hours using an organic solvent as a water carrier. After the reaction, the unreacted solid matter is removed by filtration, the solvent is removed by vacuum distillation, and the product is dried in vacuo to obtain N-alkyl imidazole diethanolamide molybdate ionic liquid;

[0015] 4) Anion exchange reaction: Using acetone as a solvent, N-alkyl imidazole diethanolamide molybdate ionic liquid is mixed with an inorganic salt and stirred at room temperature for 48 hours. After the reaction is completed, vacuum filtration is performed, organic solvent washing is performed, the solvent is removed by rotary evaporation, and vacuum drying is performed to generate a molybdate ionic liquid.

[0016] Furthermore, in step 1), the molar ratio of N-alkylimidazole:methyl bromoacetate is 1:1.1-1.5.

[0017] Furthermore, in step 1), the N-alkyl imidazole is a saturated straight-chain alkyl N-alkyl imidazole.

[0018] Furthermore, the saturated straight-chain alkyl N-alkylimidazole is selected from N-methylimidazole, N-ethylimidazole, N-butylimidazole and N-hexylimidazole.

[0019] Furthermore, in step 2), the molar ratio of 1-alkyl 3-methyl imidazolium bromide ionic liquid: diethanolamine is 1:2.0-3.0.

[0020] Furthermore, in step 3), the molar ratio of N-alkylimidazole diethanolamide ionic liquid to molybdenum ions in the molybdenum source is 1:1.0-1.5.

[0021] Furthermore, in step 3), the molybdenum source is one of molybdenum oxides or molybdates.

[0022] Furthermore, in step 4), the inorganic salt is selected from KY, K[N(CN)2], KNO2, KNO3, NH4H2PO4, NaHSO4, NaDCA, KEtSO4, KBF4, KPF6, NaAlCl4, KClO4, LiFSI, LiTFSI, NaCF3CO2 and NaOMs; and Y is a halogen.

[0023] The present invention provides a use of a molybdate ionic liquid as an additive in a water-based lubricant.

[0024] The beneficial effects of the present invention are:

[0025] 1. The molybdate ionic liquid synthesized in this invention, as a water-based lubricant additive, exhibits low metal corrosion, excellent thermal stability, and superior tribological properties. This provides a theoretical foundation for further research into the fundamental applications of molybdenum chemistry and its functional compounds, and for continuously improving the scientific and technological content and added value of molybdenum products.

[0026] 2. The present invention incorporates a synthesized molybdate ionic liquid as an additive into a water-based lubricant, effectively improving the lubrication performance and reducing the corrosiveness of the water-based lubricant. The molybdate ionic liquid in the present invention has excellent solubility in water and high stability, effectively enhancing the anti-wear and friction-reducing properties of water-soluble lubricants and significantly reducing corrosion in metal equipment. Furthermore, the structure and function of the ionic liquid can be tailored to meet specific needs, demonstrating its broad application prospects in the field of water-based lubricants. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the 1-ethylimidazole diethanolamide molybdate ionic liquid synthesized in Example 1.

[0028] Figure 2 This is a Fourier transform infrared spectrum of the 1-ethylimidazole diethanolamide molybdate ionic liquid synthesized in Example 1.

[0029] Figure 3 This is a Raman spectrum of the 1-ethylimidazole diethanolamide molybdate ionic liquid synthesized in Example 1.

[0030] Figure 4 1 is a graph showing the friction coefficient of the molybdate ionic liquids synthesized in Example 1 and Example 2.

[0031] Figure 5 1 is a wear volume diagram of the molybdate ionic liquid synthesized in Example 1 and Example 2.

[0032] Figure 6 3D contour diagrams of wear spots on the friction pair surfaces of Example 2 (left), Example 1 (middle), and pure water (right).

[0033] Figure 7 This is a graph showing the corrosion test of cast iron sheets using molybdate ionic liquids synthesized with different anions. DETAILED DESCRIPTION

[0034] Example 11-Ethyl imidazole molybdate dicyanamide salt ionic liquid (1) 1-Ethyl imidazole molybdate dicyanamide salt ionic liquid, the structural formula is as follows:

[0035]

[0036] (2) The preparation method is as follows:

[0037] 1) Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid:

[0038] Take N-ethylimidazole (9.613 g, 0.1 mol) and methyl bromoacetate (18.357 g, 0.12 mol), use 50 mL of acetonitrile as solvent, use a constant pressure funnel to slowly add methyl bromoacetate dropwise to N-ethylimidazole, stir continuously until the addition is complete, heat to 80 ° C, reflux for 8 hours, and the reaction is completed. After the liquid initial product is cooled to room temperature, add an equal volume of n-hexane for washing, and remove the solvent and excess methyl bromoacetate by rotary evaporation. Repeat the above steps 3 times, and place the resulting product in a vacuum drying oven and dry it at 80 ° C for 48 hours to obtain a brown viscous liquid, which is 1-ethyl-3-methylacetate imidazolium bromide ionic liquid for standby use.

[0039] 2) Preparation of 1-ethylimidazole diethanolamide ionic liquid

[0040] Take 1-ethyl-3-methylacetate imidazolium bromide ionic liquid (24.91 g, 0.1 mol) and diethanolamine (26.285 g, 0.25 mol), react at 70°C for 14 h, cool to room temperature, add an equal volume of n-hexane and extract repeatedly 3 to 6 times, remove the solvent by rotary evaporation, and place the resulting product in a vacuum drying oven and vacuum dry at 70°C for 48 h to obtain 1-ethylimidazole diethanolamide ionic liquid for standby use.

[0041] 3) Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid:

[0042] Take 1-ethylimidazole diethanolamide ionic liquid (33.79 g, 0.1 mol) and molybdenum trioxide (17.275 g, 0.12 mol), and under nitrogen protection, slowly add molybdenum trioxide to the 1-ethylimidazole diethanolamide ionic liquid with stirring, add an equal volume of toluene as a water agent, heat to 120 ° C and reflux for 3.5 hours. After the reaction is completed, filter out the unreacted molybdenum trioxide, and remove the water agent toluene by vacuum distillation. The resulting product is placed in a vacuum drying oven and vacuum dried at 55 ° C for 48 hours to obtain an oily dark green transparent liquid, which is 1-ethylimidazole diethanolamide molybdate ionic liquid.

[0043] 4) 1-Ethylimidazolium molybdate dicyanamide ionic liquid:

[0044] Take 1-ethylimidazole diethanolamide molybdate ionic liquid (44.79 g, 0.1 mol) and sodium dicyanamide (9.793 g, 0.11 mol), use 50 mL of acetone as solvent, mix well, stir and react at room temperature for 48 hours. After the reaction is completed, vacuum filter to remove unreacted sodium dicyanamide, and the resulting transparent solution is further washed with an equal volume of n-hexane, and the solvent is removed by rotary evaporation. The resulting product is placed in a vacuum drying oven and vacuum dried at 70°C for 120 hours to obtain 1-ethylimidazole molybdate dicyanamide salt ionic liquid.

[0045] (3) Characterization

[0046] Step 3) The product 1-ethylimidazole diethanolamide molybdate ionic liquid has a hydrogen nuclear magnetic resonance spectrum ( 1 H-NMR), Fourier transform infrared spectroscopy (FT-IR), Raman spectra, such as Figure 1-3 .

[0047] Figure 1 This is the H NMR spectrum of 1-ethylimidazole diethanolamide molybdate ionic liquid 1 H-NMR (D2O, 300 MHz, 298K): The results confirmed the synthesis of molybdate ionic liquid.

[0048] Figure 2 This is the Fourier transform infrared spectrum (FT-IR) of 1-ethylimidazole diethanolamide molybdate ionic liquid: the results confirmed that 1-ethylimidazole diethanolamide molybdate ionic liquid was synthesized.

[0049] Figure 3 This is the Raman spectrum of 1-ethylimidazole diethanolamide molybdate ionic liquid: the results confirmed the synthesis of 1-ethylimidazole diethanolamide molybdate ionic liquid.

[0050] Example 2 1-Ethylimidazolium molybdate hydrogen sulfate ionic liquid (I) has the following structural formula:

[0051]

[0052] (2) The preparation method is as follows:

[0053] 1) Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid: same as in Example 1.

[0054] 2) Preparation of 1-ethylimidazole diethanolamide ionic liquid: same as in Example 1.

[0055] 3) Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid: same as in Example 1.

[0056] 4) Preparation of 1-ethylimidazolium molybdate hydrogen sulfate ionic liquid:

[0057] Take 1-ethylimidazole diethanolamide molybdate ionic liquid (44.79 g, 0.1 mol) and sodium bisulfate (13.207 g, 0.11 mol), use 50 mL of acetone as solvent, mix well, and react with stirring at room temperature for 48 hours. After the reaction is completed, vacuum filtration is performed to remove unreacted sodium bisulfate. The resulting transparent solution is further washed with an equal volume of n-hexane, and the solvent is removed by rotary evaporation. The resulting product is placed in a vacuum drying oven and vacuum dried at 70 ° C for 120 hours to obtain 1-ethylimidazole molybdate hydrogen sulfate ionic liquid.

[0058] Example 31-Ethyl imidazole molybdate tetrafluoroborate ionic liquid (I) The structural formula is as follows:

[0059]

[0060] (2) The preparation method is as follows:

[0061] 1) Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid: same as in Example 1.

[0062] 2) Preparation of 1-ethylimidazole diethanolamide ionic liquid: same as in Example 1.

[0063] 3) Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid: same as in Example 1.

[0064] 4) Preparation of 1-ethylimidazolium molybdate tetrafluoroborate ionic liquid:

[0065] Take 1-ethylimidazole diethanolamide molybdate ionic liquid (44.79 g, 0.1 mol) and sodium tetrafluoroborate (12.077 g, 0.11 mol), use 50 mL of acetone as solvent, mix well, and react with stirring at room temperature for 48 h. After the reaction is completed, vacuum filtration is performed to remove unreacted sodium tetrafluoroborate. The resulting transparent solution is further washed with an equal volume of n-hexane, and the solvent is removed by rotary evaporation. The resulting product is placed in a vacuum drying oven and vacuum dried at 70 °C for 120 h to obtain 1-ethylimidazole molybdate tetrafluoroborate ionic liquid.

[0066] Example 41-Ethyl imidazole molybdate hexafluorophosphate ionic liquid (I) has the following structural formula:

[0067]

[0068] (2) The preparation method is as follows:

[0069] 1) Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid: same as in Example 1.

[0070] 2) Preparation of 1-ethylimidazole diethanolamide ionic liquid: same as in Example 1.

[0071] 3) Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid: same as in Example 1.

[0072] 4) Preparation of 1-ethylimidazolium molybdate hexafluorophosphate ionic liquid:

[0073] Take 44.79 g, 0.1 mol) of 1-ethylimidazole diethanolamide molybdate ionic liquid and 18.475 g, 0.11 mol) of sodium hexafluorophosphate, use 50 mL of acetone as solvent, mix well, and react with stirring at room temperature for 48 hours. After the reaction is completed, vacuum filtration is performed to remove unreacted sodium hexafluorophosphate. The resulting transparent solution is further washed with an equal volume of n-hexane, and the solvent is removed by rotary evaporation. The resulting product is placed in a vacuum drying oven and vacuum dried at 70°C for 120 hours to obtain 1-ethylimidazole molybdate hexafluorophosphate ionic liquid.

[0074] Example 51-Ethyl imidazole molybdate bis(trifluoromethanesulfonyl)imide salt ionic liquid (I) has the following structural formula:

[0075]

[0076] (2) The preparation method is as follows:

[0077] 1) Preparation of 1-ethyl-3-methylacetate imidazolium bromide ionic liquid: same as in Example 1.

[0078] 2) Preparation of 1-ethylimidazole diethanolamide ionic liquid: same as in Example 1.

[0079] 3) Preparation of 1-ethylimidazole diethanolamide molybdate ionic liquid: same as in Example 1.

[0080] 4) Preparation of 1-ethyl imidazole molybdate bis trifluoromethanesulfonyl imide salt ionic liquid:

[0081] Take 44.79 g, 0.1 mol) of 1-ethylimidazole diethanolamide molybdate ionic liquid and 31.579 g, 0.11 mol) of lithium bis(trifluoromethanesulfonyl imide) and use 50 mL of acetone as solvent, mix well, and react with stirring at room temperature for 48 hours. After the reaction is completed, vacuum filtration is performed to remove unreacted lithium bis(trifluoromethanesulfonyl imide). The resulting transparent solution is further washed with an equal volume of n-hexane, and the solvent is removed by rotary evaporation. The resulting product is placed in a vacuum drying oven and vacuum dried at 70 ° C for 120 hours to obtain 1-ethylimidazole molybdate bis(trifluoromethanesulfonyl imide) salt ionic liquid.

[0082] Example 6 Application

[0083] The tribological properties of aqueous solutions of the products of Example 1 and Example 2 were evaluated using a micro-vibration friction and wear tester. The contact mode of the friction pair is ball-disk point contact. The upper ball is an AISI52100 bearing steel ball with a diameter of 10 mm, an average roughness of about 0.02 μm, and a hardness of 700-800 HV. The lower disk is an AISI52100 bearing steel disk with a diameter of 24 mm, a height of 7.9 mm, an average roughness of about 0.02 μm, and a hardness of 700-800 HV. The test conditions are: temperature 25°C, frequency 25 Hz, amplitude 1 mm, load 100 N, experimental time 30 min, relative humidity 40-50%. The wear spots on the surface of the steel block after the SRV experiment were analyzed by the non-contact surface mapping MicroXAM-3D three-dimensional profiler, and the wear volume was calculated, as shown in Figure 3. Figure 5 .

[0084] Figure 4 The friction coefficient curves of the products of Example 1 and Example 2 are as follows: the results show that, compared with the friction coefficient of pure water of 0.5-0.7, the synthesized ionic liquid as a water-based lubricating additive can reduce the friction coefficient of the friction pair surface.

[0085] Figure 5 The wear volume data of the products of Example 1 and Example 2 are shown in FIG. 1 : The results show that the wear volume of the synthesized molybdate ionic liquid solution is reduced by more than 38% compared with pure water, and can effectively play an anti-wear and friction-reducing role.

[0086] Figure 6It is a three-dimensional contour diagram of the wear spots on the friction pair surfaces of Example 2 (left), Example 1 (middle) and pure water (right): The results show that the wear spot area and depth of the steel block are reduced, and the synthesized molybdate ionic liquid can effectively play an anti-wear and friction-reducing role.

[0087] Figure 7 This is a graph showing corrosion tests on cast iron sheets using molybdate ionic liquids with different anions in Examples 1-5: The results show that compared with the severe corrosion and discoloration caused by pure water on the cast iron sheets, the synthesized molybdate ionic liquid can, to a certain extent, mitigate water corrosion on the friction pair surface.

Claims

1. A molybdate ionic liquid, characterized in that The molybdate ionic liquid has the structural formula shown in (I), in, R' is an ethyl molybdate ionic liquid; X is selected from halogen, [N(CN)2] - 、[NO2] - 、[NO3] - 、[H2PO4] - , [HSO4] - , [DCA] - , [EtSO4] - 、[BF4] - 、 [PF6] - 、[AlCl4] - , [ClO4] - , [FSI] - , [TFSI] - , [CF3CO2] - and [OMs] - One of them.

2. The method for preparing a molybdate ionic liquid according to claim 1, wherein The preparation method comprises the following steps: 1) reacting N-alkyl imidazole with methyl bromoacetate at 70-90° C. for 8-10 hours, cooling to room temperature, washing, and removing the solvent and excess methyl bromoacetate by rotary evaporation to obtain a 1-alkyl-3-methyl acetate imidazole bromide ionic liquid; 2) Amidation reaction: reacting 1-alkyl-3-methyl imidazolium bromide ionic liquid with diethanolamine at 70-90°C for 13-15 hours, cooling to room temperature, adding an organic solvent for extraction, removing the solvent by rotary evaporation, and vacuum drying to obtain N-alkyl imidazole diethanolamide ionic liquid; 3) Molybdenumation reaction: Under nitrogen protection, take N-alkyl imidazole diethanolamide ionic liquid and molybdenum source, use organic solvent as water carrier, reflux reaction at 115-120°C for 3-4 hours. After the reaction, filter out unreacted solid matter, remove the solvent by vacuum distillation, and vacuum dry to obtain N-alkyl imidazole diethanolamide molybdate ionic liquid; 4) Anion exchange reaction: Using acetone as a solvent, N-alkyl imidazole diethanolamide molybdate ionic liquid is mixed with an inorganic salt, stirred at room temperature for 48 hours, and after the reaction is completed, vacuum filtration is performed, washed with an organic solvent, the solvent is removed by rotary evaporation, and vacuum drying is performed to generate a molybdate ionic liquid.

3. The preparation method according to claim 2, characterized in that In step 1), the molar ratio of N-alkylimidazole:methyl bromoacetate is 1:1.1-1.

5.

4. The preparation method according to claim 2, characterized in that In step 1), the N-alkyl imidazole is a saturated straight-chain alkyl N-alkyl imidazole.

5. The preparation method according to claim 4, characterized in that The saturated straight-chain alkyl N-alkylimidazole is selected from N-methylimidazole, N-ethylimidazole, N-butylimidazole and N-hexylimidazole.

6. The preparation method according to claim 2, characterized in that In step 2), the molar ratio of 1-alkyl 3-methyl imidazolium bromide ionic liquid: diethanolamine is 1:2.0-3.

0.

7. The preparation method according to claim 2, characterized in that In step 3), the molar ratio of N-alkyl imidazole diethanolamide ionic liquid to molybdenum ions in the molybdenum source is 1:1.0-1.

5.

8. The preparation method according to claim 2, characterized in that In step 3), the molybdenum source is one of molybdenum oxides or molybdates.

9. The preparation method according to claim 2, characterized in that In step 4), the inorganic salt is selected from KY, K[N(CN)2], KNO2, KNO3, NH4H2PO4, NaHSO4, NaDCA, KEtSO4, KBF4, KPF6, NaAlCl4, KClO4, LiFSI, LiTFSI, NaCF3CO2 and NaOMs; Y is a halogen; in a molar ratio, N-alkylimidazole diethanolamide molybdate ionic liquid: inorganic salt = 1:1.

1.

10. Use of the molybdate ionic liquid according to claim 1 as an additive in a water-based lubricant.

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