A lubricating oil dispersant based on a mof composite and a method for its preparation

Abstract

The application discloses a kind of based on MOF composite material lubricating oil dispersant and preparation method thereof, belong to lubricating oil additive technical field, by the following component according to mass percentage composition: MOF composite material 8%—18%, modified carrier 45%—65%, functional adjuvant 8%—22%, the balance is base oil, using amino grafting modified carbon nanotube in situ growth amino modified UIO-66 MOF forms MOF composite material, through the design of "tube-crystal" interlocking structure, effectively solve the technical problems of single MOF easy to agglomerate, poor dispersion stability;Amino grafting modified carbon nanotube not only provides specific binding site for MOF in situ growth, its tubular structure can also play a space limiting effect on MOF, avoid MOF particle growth agglomeration.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil additive technology, specifically relating to a lubricating oil dispersant based on MOF composite materials and its preparation method. Background Technology

[0002] During the operation of engines and mechanical equipment, lubricating oil will produce impurities such as carbon deposits, sludge, and metal abrasive particles due to high-temperature oxidation and component wear. If these impurities are not dispersed in time, they will lead to increased lubricating oil viscosity, decreased fluidity, accelerated component wear, and shortened service life of both the lubricating oil and the equipment. Therefore, as one of the core additives in lubricating oil, the performance of dispersants directly determines the dispersing and purifying ability and long-term stability of the lubricating oil. Currently, existing lubricating oil dispersants are mainly polyisobutylene succinimide-based. Although these dispersants have a certain dispersing effect, they have defects such as poor dispersion stability, easy failure at high temperatures, and limited abrasive particle adsorption capacity, making it difficult to meet the requirements of high-end mechanical equipment for long-term and efficient dispersion of lubricating oil.

[0003] Metal-organic frameworks (MOFs) have been explored for use in lubricating oil dispersants due to their large specific surface area, controllable pore structure, and good adsorption properties. However, single MOF materials suffer from problems such as easy agglomeration, poor compatibility with lubricating oil, and difficulty in achieving long-term dispersion, which limits their practical application. In addition, although existing technologies have attempted to prepare dispersants by combining MOFs with supports, most of them use simple mixing methods. The binding strength between MOFs and supports is low, and they are easy to detach from the support surface, which fails to give full play to the adsorption and dispersion effects of MOFs. Summary of the Invention

[0004] The purpose of this invention is to provide a lubricating oil dispersant based on MOF composite materials and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a lubricating oil dispersant based on MOF composite material, comprising the following components by mass percentage: 8%-18% MOF composite material, 45%-65% modified carrier, 8%-22% functional additives, and the balance being base oil; The MOF composite material is a composite of amino-modified UIO-66 MOF grown in situ on amino-grafted modified carbon nanotubes. The surface grafting rate of the amino-grafted modified carbon nanotubes is 3.2%-5.8%, and the particle size of the amino-modified UIO-66 MOF is 30-80 nm. It is grown in situ on the surface and inside the lumen of the amino-grafted modified carbon nanotubes. The modified carrier is epoxy group modified polyisobutylene succinimide with an epoxy value of 0.08-0.15 eq / 100g, and the functional additive is composed of antioxidant and dispersant stabilizer in a mass ratio of 2-3:1.

[0006] This invention also discloses a method for preparing a lubricating oil dispersant based on MOF composite materials, comprising the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: Add carbon nanotubes to an ethanol-deionized water mixed solution, ultrasonically disperse for 15-30 min until a uniform suspension is formed, add aminosilane coupling agent KH-550, heat to 65-85℃, stir at a constant temperature for 3-5 h, centrifuge, wash, and vacuum dry to constant weight to obtain amino-grafted modified carbon nanotubes. S2. Dissolve zirconium salt and 2-aminoterephthalic acid in N,N-dimethylformamide and stir until completely dissolved. Add the amino-grafted modified carbon nanotubes prepared in step S1, and ultrasonically disperse for 20-40 min. Adjust the pH of the system to 6.5-7.5, raise the temperature to 100-130℃, and carry out the in-situ coordination reaction at a constant temperature for 6-10 h. After the reaction is completed, cool to room temperature, centrifuge, wash, and vacuum dry to constant weight to obtain the MOF composite material. S3. Preparation of modified carrier: Polyisobutylene succinimide was added to toluene, stirred and dissolved, and then epichlorohydrin was added. The temperature was raised to 45-65℃ and stirred at a constant temperature for 2-4 hours. After the reaction was completed, toluene and unreacted epichlorohydrin were removed by distillation to obtain epoxy group modified polyisobutylene succinimide. S4. Preparation of lubricating oil dispersant: Add the modified carrier and base oil prepared in step S3 to the reaction vessel, heat to 80-100℃, stir until completely dissolved, add the MOF composite material prepared in step S2, ultrasonically disperse for 30-50 min, then add functional additives, heat to 110-140℃, stir at a constant temperature for 4-7 h, cool to room temperature after the reaction is completed, filter to remove impurities, and obtain the lubricating oil dispersant based on MOF composite material.

[0007] In a preferred embodiment, the zirconium salt is one or a mixture of two of zirconium chloride and zirconium oxychloride in any proportion, and the molar ratio of the zirconium salt to 2-aminoterephthalic acid is 1:1.2-1.8.

[0008] In a preferred embodiment, the base oil is one or a mixture of two of PAO4 and PAO6 in any proportion.

[0009] In a preferred embodiment, in step S1, the volume ratio of ethanol to deionized water in the ethanol-deionized water mixed solution is 3-5:1, and the mass ratio of carbon nanotubes to aminosilane coupling agent KH-550 is 10:1.5-3.0.

[0010] In a preferred embodiment, in step S2, the mass ratio of the zirconium salt, 2-aminoterephthalic acid, and amino-grafted modified carbon nanotubes is 1:1.5-2.0:0.8-1.5.

[0011] In a preferred embodiment, in step S3, the mass ratio of polyisobutylene succinimide to epichlorohydrin is 10:2.5-4.5, and the number average molecular weight of the polyisobutylene succinimide is 1500-3500. In a preferred embodiment, in step 4, the power of the ultrasonic dispersion is 300-500W, and the rotation speed of the constant temperature stirring is 300-500r / min.

[0012] In a preferred embodiment, in step S2, the washing is performed by alternating washing with N,N-dimethylformamide and ethanol 3-5 times; in steps S1, S2 and S3, the vacuum drying temperature is 80-100℃ and the drying time is 8-12h.

[0013] In a preferred embodiment, the antioxidant is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1-2, and the dispersant is polyether dispersant L64.

[0014] Compared with the prior art, the beneficial effects of the present invention are: In this invention, amino-grafted modified carbon nanotubes are used to support in-situ grown amino-modified UIO-66 MOF to form a MOF composite material. Through the design of the "tube-crystal" interlocking structure, the technical problems of easy agglomeration and poor dispersion stability of single MOF are effectively solved. The amino-grafted modified carbon nanotubes not only provide specific binding sites for in-situ growth of MOF, but their tubular structure can also play a spatial confinement role for MOF, avoiding the growth and agglomeration of MOF particles. At the same time, the MOF grows in situ on the surface and inside the tube of carbon nanotube, and is firmly bound to the carbon nanotube. It can give full play to the adsorption advantage of the ultra-large specific surface area of ​​MOF, efficiently adsorb impurities such as carbon deposits and abrasive particles in lubricating oil, and improve the dispersion and purification ability of dispersant. In this invention, the modified carrier is designed as epoxy group modified polyisobutylene succinimide. The epoxy group can undergo a cross-linking reaction with the amino groups on the surface of the MOF composite material to form a stable chemical bond, which significantly enhances the bonding strength between the MOF composite material and the modified carrier, prevents the MOF composite material from falling off the carrier surface, effectively improves the long-term dispersion stability of the dispersant, solves the defects of weak bonding and easy detachment between MOF and carrier in the prior art, and extends the service life of the dispersant. In this invention, the synergistic effect of each component achieves a synergistic improvement in dispersion performance and antioxidant performance. The hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in the functional additives can exert a synergistic antioxidant effect, effectively inhibiting high-temperature oxidation of lubricating oil, reducing the generation of carbon deposits and sludge, and reducing dispersion pressure from the source. The polyether dispersion stabilizer L64 can help improve the dispersion uniformity of MOF composite material in the lubricating oil system, and synergistically with MOF composite material and modified carrier to further optimize the dispersion effect. In this invention, the preparation method has clear steps and strong correlation, with each step sequentially connected and working synergistically: the amino grafting modification in step S1 provides the basis for the in-situ growth of MOF in step S2; the preparation of MOF composite material in step S2 provides the core functional component for the component fusion in step S4; and the preparation of modified carrier in step S3 ensures the fixation and dispersion of MOF composite material. The entire process is highly controllable, simple to operate, requires no complex equipment, and is suitable for large-scale industrial production. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the steps in the preparation method of the lubricating oil dispersant based on MOF composite material of the present invention; Detailed Implementation

[0016] The present invention will be further described below with reference to embodiments.

[0017] The following embodiments are used to illustrate the present invention, but should not be used to limit the scope of protection of the present invention. The conditions in the embodiments can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention are all within the scope of protection claimed by the present invention.

[0018] Please see Figure 1 The present invention provides a lubricating oil dispersant based on MOF composite material, which is composed of the following components by mass percentage: 8%-18% MOF composite material, 45%-65% modified carrier, 8%-22% functional additives, and the balance being base oil.

[0019] The MOF composite material is a complex of amino-modified UIO-66MOF grown in situ on amino-grafted modified carbon nanotubes. The surface grafting rate of the amino-grafted modified carbon nanotubes is 3.2%-5.8%, and the particle size of the amino-modified UIO-66MOF is 30-80 nm. It grows in situ on the surface and inside the cavity of the amino-grafted modified carbon nanotubes. Through the coordination between the amino groups on the surface of the amino-grafted modified carbon nanotubes and the amino-modified UIO-66MOF precursor, the in-situ growth of MOF is achieved, forming a "tube-crystal" interlocking structure, which effectively avoids MOF aggregation and improves the bonding strength between MOF and carbon nanotubes.

[0020] The modified carrier is epoxy-modified polyisobutylene succinimide with an epoxy value of 0.08-0.15 eq / 100g. The introduction of epoxy groups can cross-link with the amino groups on the surface of the MOF composite material, further enhancing the bonding strength between the MOF composite material and the modified carrier, preventing the MOF composite material from falling off the carrier surface, and improving the long-term stability of the dispersant.

[0021] The functional additives are composed of antioxidants and dispersants in a mass ratio of 2-3:1. The antioxidants are hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1-2, which can effectively inhibit the high-temperature oxidation of lubricating oil and reduce the generation of carbon deposits and sludge. The dispersant is polyether dispersant L64, which can help improve the dispersion uniformity of MOF composites in the lubricating oil system and further optimize the dispersion effect.

[0022] The base oil is a mixture of one or two of PAO4 and PAO6 in any proportion. Both PAO4 and PAO6 are polyalphaolefin synthetic base oils with high viscosity index, excellent high and low temperature performance, good oxidation stability and low volatility. They have good compatibility with MOF composites, modified carriers and functional additives, and can provide a stable carrier environment for dispersants, ensuring the full play of the synergistic effect of each component. PAO4 has excellent low temperature fluidity and PAO6 has outstanding high temperature stability. The two can be flexibly proportioned according to the actual use conditions to adapt to different high and low temperature requirements.

[0023] In MOF composite materials, the diameter of amino-grafted modified carbon nanotubes is 20-50 nm and the length is 1-5 μm. In the "tube-crystal" interlocking structure, the loading of amino-modified UIO-66MOF on the surface of carbon nanotubes is 35-60 wt%. This loading can ensure that MOF can fully exert its adsorption and dispersion effect, while avoiding MOF agglomeration caused by excessive loading.

[0024] The zirconium salt is one or a mixture of zirconium chloride and zirconium oxychloride in any proportion. The molar ratio of zirconium salt to 2-aminoterephthalic acid is 1:1.2-1.8. This molar ratio ensures that 2-aminoterephthalic acid is fully coordinated to form an amino-modified UIO-66MOF with stable structure and uniform particle size.

[0025] This invention also discloses a method for preparing the above-mentioned lubricating oil dispersant based on MOF composite materials, comprising the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: Carbon nanotubes are added to an ethanol-deionized water mixed solution and ultrasonically dispersed for 15-30 min until a uniform suspension is formed. The volume ratio of ethanol to deionized water in the ethanol-deionized water mixed solution is 3-5:1, and the mass ratio of carbon nanotubes to aminosilane coupling agent KH-550 is 10:1.5-3.0. Subsequently, aminosilane coupling agent KH-550 is added, the temperature is raised to 65-85℃, and the reaction is carried out with stirring at a constant temperature for 3-5 h. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to constant weight to obtain amino-grafted modified carbon nanotubes. This step modifies carbon nanotubes by grafting with aminosilane coupling agent KH-550, introducing amino groups on the surface of carbon nanotubes, providing specific binding sites for subsequent in-situ MOF growth, and improving the compatibility of carbon nanotubes with MOF and modified carrier, while avoiding carbon nanotube aggregation.

[0026] S2. Preparation of MOF composite material: Dissolve zirconium salt and 2-aminoterephthalic acid in N,N-dimethylformamide and stir until completely dissolved. The mass ratio of zirconium salt, 2-aminoterephthalic acid, and amino-grafted modified carbon nanotubes is 1:1.5-2.0:0.8-1.5. Add the amino-grafted modified carbon nanotubes prepared in step S1, and ultrasonically disperse for 20-40 min. Adjust the pH of the system to 6.5-7.5 (using dilute ammonia and dilute hydrochloric acid for synergistic adjustment to ensure pH stability). Heat to 100-130℃ and maintain the temperature for in-situ coordination reaction for 6-10 h. After cooling to room temperature, centrifugation and washing were performed. The washing process involved alternating between N,N-dimethylformamide and ethanol for 3-5 times to remove unreacted precursors and impurities. Subsequently, the mixture was vacuum dried to constant weight to obtain the MOF composite material. This step relies on the coordination between the amino groups on the surface of the modified carbon nanotubes in step S1 and the MOF precursors (zirconium salt, 2-aminoterephthalic acid) to achieve in-situ growth of MOF on the surface and in the lumen of carbon nanotubes, forming a "tube-crystal" interlocking structure. This effectively solves the problems of easy aggregation and poor dispersion stability of single MOFs, while improving the bonding strength between MOF and carbon nanotubes.

[0027] S3. Preparation of modified carrier: Polyisobutylene succinimide is added to toluene and stirred until dissolved. Then epichlorohydrin is added, wherein the mass ratio of polyisobutylene succinimide to epichlorohydrin is 10:2.5-4.5, and the number average molecular weight of polyisobutylene succinimide is 1500-3500. The temperature is raised to 45-65℃ and stirred for 2-4 hours. After the reaction is completed, toluene and unreacted epichlorohydrin are removed by distillation to obtain epoxy group modified polyisobutylene succinimide. In this step, epoxy groups are introduced into the molecular chain of polyisobutylene succinimide by epichlorohydrin to modify it with epoxy groups, so that the carrier can undergo cross-linking reaction with the amino groups on the surface of the MOF composite material prepared in step S2, thereby enhancing the bonding strength between the MOF composite material and the carrier and improving the long-term stability of the dispersant.

[0028] S4. Preparation of Lubricating Oil Dispersant: Add the modified carrier and base oil prepared in step S3 to the reactor, heat to 80-100℃, and stir until completely dissolved; add the MOF composite material prepared in step S2, and ultrasonically disperse for 30-50 min (ultrasonic dispersion power of 300-500W) to ensure that the MOF composite material is uniformly dispersed in the system; then add the functional additives, heat to 110-140℃, and stir at a constant temperature for 4-7 h (stirring speed of 300-500 r / min) to ensure that the various functional additives are uniformly dispersed in the system. The components are fully integrated and synergistically combined. After the reaction is completed, the mixture is cooled to room temperature and impurities are removed by filtration using a 0.22 μm organic filter membrane at a filtration pressure of 0.1-0.3 MPa to obtain a lubricating oil dispersant based on MOF composite material. In this step, the modified carrier, MOF composite material, and functional additives are added sequentially. Through the synergistic effect of ultrasonic dispersion and constant temperature stirring, the components are uniformly integrated. Relying on the modification effects of steps S2 and S3, the dispersant has excellent dispersibility, antioxidant properties, and abrasive adsorption and purification capabilities.

[0029] Furthermore, in steps S1, S2, and S3, the vacuum drying temperature is 80-100℃ and the drying time is 8-12h to ensure thorough drying and avoid residual moisture or solvent affecting product performance; in steps S1 and S2, the centrifugation speed is 8000-12000r / min and the centrifugation time is 10-20min to fully separate the product and remove unreacted impurities.

[0030] This invention utilizes amino-grafted modified carbon nanotubes to support in-situ grown amino-modified UIO-66MOF to form a MOF composite material. Through the design of the "tube-crystal" interlocking structure, it effectively solves the technical problems of easy agglomeration and poor dispersion stability of single MOF. The amino-grafted modified carbon nanotubes not only provide specific binding sites for in-situ growth of MOF, but their tubular structure also plays a spatial confinement role for MOF, preventing MOF particles from growing and agglomerating. At the same time, the MOF grows in situ on the surface and inside the tube of carbon nanotube, and is firmly bound to the carbon nanotube. It can give full play to the adsorption advantage of the ultra-large specific surface area of ​​MOF, efficiently adsorb impurities such as carbon deposits and abrasive particles in lubricating oil, and improve the dispersion and purification ability of dispersants.

[0031] This invention designs the modified carrier as epoxy-modified polyisobutylene succinimide. The epoxy groups can undergo cross-linking reactions with the amino groups on the surface of the MOF composite material to form a stable chemical bond, which significantly enhances the bonding strength between the MOF composite material and the modified carrier, prevents the MOF composite material from falling off the carrier surface, effectively improves the long-term dispersion stability of the dispersant, solves the defects of weak bonding and easy detachment of MOF and carrier in the prior art, and extends the service life of the dispersant.

[0032] This invention achieves a synergistic improvement in dispersion and antioxidant properties through the synergistic effect of its components: the hindered phenolic antioxidant 1010 and the phosphite antioxidant 168 in the functional additives can exert a synergistic antioxidant effect, effectively inhibiting high-temperature oxidation of lubricating oil, reducing the generation of carbon deposits and sludge, and reducing dispersion pressure from the source; the polyether dispersion stabilizer L64 can help improve the dispersion uniformity of MOF composite materials in the lubricating oil system, and synergistically with MOF composite materials and modified carriers to further optimize the dispersion effect; the selection of PAO base oil not only has good compatibility with each component, but its excellent high and low temperature performance and oxidation stability can also provide a stable environment for the dispersant to perform, making the dispersant adaptable to different high and low temperature conditions and expanding its application range.

[0033] The preparation method of the present invention has clear steps and strong correlation, with each step connected sequentially and working synergistically: the amino grafting modification in step S1 provides the basis for the in-situ growth of MOF in step S2; the preparation of MOF composite material in step S2 provides the core functional component for the component fusion in step S4; and the preparation of modified carrier in step S3 ensures the fixation and dispersion of MOF composite material. The whole process is highly controllable, simple to operate, requires no complex equipment, and is suitable for large-scale industrial production.

[0034] Example 1 A lubricating oil dispersant based on MOF composite material, comprising the following components by mass percentage: 13% MOF composite material, 55% modified carrier, 15% functional additives, and 17% base oil (the base oil is a mixture of PAO4 and PAO6 in a mass ratio of 1:1).

[0035] The MOF composite material is a composite of amino-grafted modified carbon nanotubes (grafting rate 4.5%, tube diameter 35nm, length 3μm) loaded with in-situ grown amino-modified UIO-66MOF (particle size 55nm), with the MOF loading amount on the carbon nanotube surface being 48wt%. The modified carrier is epoxy-modified polyisobutylene succinimide (epoxy value 0.11eq / 100g). The functional additives are composed of antioxidants (hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1.5) and dispersant stabilizer L64 in a mass ratio of 2.5:1. The zirconium salt is zirconium chloride, and the molar ratio of zirconium salt to 2-aminoterephthalic acid is 1:1.5.

[0036] The method for preparing this dispersant includes the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: 10g of carbon nanotubes were added to 100mL of ethanol-deionized water mixed solution (volume ratio 4:1), and ultrasonically dispersed for 22min to form a uniform suspension. 2.2g of aminosilane coupling agent KH-550 was added, the temperature was raised to 75℃, and the reaction was stirred at a constant temperature for 4h. After the reaction was completed, the mixture was centrifuged at 10000r / min for 15min, washed 3 times with ethanol, and vacuum dried at 90℃ for 10h to constant weight to obtain amino-grafted modified carbon nanotubes.

[0037] S2. Preparation of MOF composite material: Dissolve 10g zirconium chloride and 15g 2-aminoterephthalic acid in 200mL N,N-dimethylformamide and stir until completely dissolved. Add 12g of amino-grafted modified carbon nanotubes prepared in step S1 and sonicate for 30min. Adjust the pH of the system to 7.0 with dilute ammonia and dilute hydrochloric acid. Heat to 115℃ and carry out in-situ coordination reaction at constant temperature for 8h. After the reaction is completed, cool to room temperature and centrifuge at 10000r / min for 15min. Wash with N,N-dimethylformamide and ethanol alternately 4 times. Dry under vacuum at 90℃ for 10h to constant weight to obtain MOF composite material.

[0038] S3. Preparation of modified carrier: 100g of polyisobutylene succinimide (number average molecular weight 2500) was added to 150mL of toluene, stirred and dissolved, and then 35g of epichlorohydrin was added. The temperature was raised to 55℃ and stirred at a constant temperature for 3h. After the reaction was completed, toluene and unreacted epichlorohydrin were removed by distillation to obtain epoxy group modified polyisobutylene succinimide.

[0039] S4. Preparation of lubricating oil dispersant: Add 55g of the modified carrier prepared in step S3 and 17g of base oil to the reaction vessel, heat to 90℃, and stir until completely dissolved; add 13g of the MOF composite material prepared in step S2, and ultrasonically disperse for 40min at 400W power; then add 15g of functional additive, heat to 125℃, and stir at a constant temperature of 400r / min for 5.5h; after the reaction is completed, cool to room temperature, and filter to remove impurities using a 0.22μm organic filter membrane at a filtration pressure of 0.2MPa to obtain the lubricating oil dispersant based on the MOF composite material.

[0040] Example 2 A lubricating oil dispersant based on MOF composite material, comprising the following components by mass percentage: 8% MOF composite material, 65% modified carrier, 8% functional additives, and 19% base oil (the base oil is PAO4).

[0041] The MOF composite material is a composite of amino-grafted modified carbon nanotubes (grafting rate 3.2%, tube diameter 20nm, length 1μm) loaded with in-situ grown amino-modified UIO-66MOF (particle size 30nm), with the MOF loading amount on the carbon nanotube surface being 35wt%. The modified carrier is epoxy-modified polyisobutylene succinimide (epoxy value 0.08eq / 100g). The functional additives are composed of antioxidants (hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1) and dispersant stabilizer L64 in a mass ratio of 2:1. The zirconium salt is zirconium oxychloride, and the molar ratio of zirconium salt to 2-aminoterephthalic acid is 1:1.2.

[0042] The method for preparing this dispersant includes the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: 10g of carbon nanotubes were added to 100mL of ethanol-deionized water mixed solution (volume ratio 3:1), and ultrasonically dispersed for 15min until a uniform suspension was formed. 1.5g of aminosilane coupling agent KH-550 was added, the temperature was raised to 65℃, and the reaction was stirred at a constant temperature for 3h. After the reaction was completed, the mixture was centrifuged at 8000r / min for 10min, washed 3 times with ethanol, and vacuum dried at 80℃ for 8h until constant weight was obtained to obtain amino-grafted modified carbon nanotubes.

[0043] S2. Preparation of MOF composite material: Dissolve 10g zirconium oxychloride and 12g 2-aminoterephthalic acid in 200mL N,N-dimethylformamide and stir until completely dissolved. Add 8g of amino-grafted modified carbon nanotubes prepared in step S1 and sonicate for 20min. Adjust the pH of the system to 6.5 with dilute ammonia and dilute hydrochloric acid. Heat to 100℃ and carry out in-situ coordination reaction at constant temperature for 6h. After the reaction is completed, cool to room temperature and centrifuge at 8000r / min for 10min. Wash three times alternately with N,N-dimethylformamide and ethanol. Dry under vacuum at 80℃ for 8h to constant weight to obtain MOF composite material.

[0044] S3. Preparation of modified carrier: 100g of polyisobutylene succinimide (number average molecular weight 1500) was added to 150mL of toluene, stirred and dissolved, and then 25g of epichlorohydrin was added. The temperature was raised to 45℃ and stirred at a constant temperature for 2h. After the reaction was completed, toluene and unreacted epichlorohydrin were removed by distillation to obtain epoxy group modified polyisobutylene succinimide.

[0045] S4. Preparation of lubricating oil dispersant: Add 65g of the modified carrier prepared in step S3 and 19g of base oil to the reaction vessel, heat to 80℃, and stir until completely dissolved; add 8g of the MOF composite material prepared in step S2, and ultrasonically disperse for 30min at 300W power; then add 8g of functional additives, heat to 110℃, and stir at a constant temperature of 300r / min for 4h; after the reaction is completed, cool to room temperature, and filter to remove impurities using a 0.22μm organic filter membrane at a filtration pressure of 0.1MPa to obtain the lubricating oil dispersant based on the MOF composite material.

[0046] Example 3 A lubricating oil dispersant based on MOF composite material is composed of the following components by mass percentage: 18% MOF composite material, 45% modified carrier, 22% functional additives, and 15% base oil (the base oil is PAO6).

[0047] Among them, the MOF composite material is a composite of amino-grafted modified carbon nanotubes (grafting rate 5.8%, tube diameter 50nm, length 5μm) loaded with in-situ grown amino-modified UIO-66MOF (particle size 80nm), with the MOF loading amount on the carbon nanotube surface being 60wt%; the modified carrier is epoxy group modified polyisobutylene succinimide (epoxy value 0.15eq / 100g); the functional additives are composed of antioxidants (hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:2) and dispersant stabilizer L64 in a mass ratio of 3:1; the zirconium salt is composed of zirconium chloride and zirconium oxychloride in a mass ratio of 1:1, and the molar ratio of zirconium salt to 2-aminoterephthalic acid is 1:1.8.

[0048] The method for preparing this dispersant includes the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: 10g of carbon nanotubes were added to 100mL of ethanol-deionized water mixed solution (volume ratio 5:1), and ultrasonically dispersed for 30min to form a uniform suspension. 3.0g of aminosilane coupling agent KH-550 was added, the temperature was raised to 85℃, and the reaction was stirred at a constant temperature for 5h. After the reaction was completed, the mixture was centrifuged at 12000r / min for 20min, washed 3 times with ethanol, and vacuum dried at 100℃ for 12h to constant weight to obtain amino-grafted modified carbon nanotubes.

[0049] S2. Preparation of MOF composite material: Dissolve 10g of mixed zirconium salt (5g zirconium chloride, 5g zirconium oxychloride) and 18g of 2-aminoterephthalic acid in 200mL of N,N-dimethylformamide and stir until completely dissolved. Add 15g of amino-grafted modified carbon nanotubes prepared in step S1 and ultrasonically disperse for 40min. Adjust the pH of the system to 7.5 with dilute ammonia and dilute hydrochloric acid. Heat to 130℃ and maintain the temperature for in-situ coordination reaction for 10h. After the reaction, cool to room temperature and centrifuge at 12000r / min for 20min. Wash with N,N-dimethylformamide and ethanol alternately 5 times and vacuum dry at 100℃ for 12h to constant weight to obtain MOF composite material.

[0050] S3. Preparation of modified carrier: 100g of polyisobutylene succinimide (number average molecular weight 3500) was added to 150mL of toluene, stirred and dissolved, and then 45g of epichlorohydrin was added. The temperature was raised to 65℃ and stirred at a constant temperature for 4h. After the reaction was completed, toluene and unreacted epichlorohydrin were removed by distillation to obtain epoxy group modified polyisobutylene succinimide.

[0051] S4. Preparation of lubricating oil dispersant: Add 45g of the modified carrier prepared in step S3 and 15g of base oil to the reaction vessel, heat to 100℃, and stir until completely dissolved; add 18g of the MOF composite material prepared in step S2, and ultrasonically disperse for 500W for 50min; then add 22g of functional additives, heat to 140℃, and stir at a constant temperature of 500r / min for 7h; after the reaction is completed, cool to room temperature, and filter to remove impurities using a 0.22μm organic filter membrane at a filtration pressure of 0.3MPa to obtain the lubricating oil dispersant based on the MOF composite material.

[0052] The dispersants prepared in Examples 1 and 2 of this invention were compared with commercially available polyisobutylene succinimide dispersants (comparative samples) for performance testing. The test items and results are shown in Table 1 below. ; Table 1 As can be seen from the above test results, the dispersants prepared in Examples 1, 2 and 3 of this invention are significantly superior to existing commercially available dispersants in terms of dispersion stability, abrasive adsorption capacity, high-temperature antioxidant lifespan and low-temperature fluidity. Among them, Example 3 has the best performance in dispersion stability, abrasive adsorption capacity and high-temperature antioxidant lifespan due to its high MOF loading and high proportion of functional additives. This fully demonstrates that the dispersant of this invention has excellent comprehensive performance and has achieved the expected invention purpose.

Claims

1. A lubricating oil dispersant based on MOF composite materials, characterized in that, It is composed of the following components by mass percentage: 8%-18% MOF composite material, 45%-65% modified carrier, 8%-22% functional additives, and the balance being base oil; The MOF composite material is a composite of amino-modified UIO-66 MOF grown in situ on amino-grafted modified carbon nanotubes. The surface grafting rate of the amino-grafted modified carbon nanotubes is 3.2%-5.8%, and the particle size of the amino-modified UIO-66 MOF is 30-80 nm. It is grown in situ on the surface and inside the lumen of the amino-grafted modified carbon nanotubes. The modified carrier is epoxy group modified polyisobutylene succinimide with an epoxy value of 0.08-0.15 eq / 100g, and the functional additive is composed of antioxidant and dispersant stabilizer in a mass ratio of 2-3:

1.

2. A method for preparing a lubricating oil dispersant based on MOF composite materials, comprising the lubricating oil dispersant based on MOF composite materials as described in claim 1, further comprising the following steps: S1. Preparation of amino-grafted modified carbon nanotubes: Add carbon nanotubes to an ethanol-deionized water mixed solution, ultrasonically disperse for 15-30 min until a uniform suspension is formed, add aminosilane coupling agent KH-550, heat to 65-85℃, stir at a constant temperature for 3-5 h, centrifuge, wash, and vacuum dry to constant weight to obtain amino-grafted modified carbon nanotubes. S2. Dissolve zirconium salt and 2-aminoterephthalic acid in N,N-dimethylformamide and stir until completely dissolved. Add the amino-grafted modified carbon nanotubes prepared in step S1, and ultrasonically disperse for 20-40 min. Adjust the pH of the system to 6.5-7.5, raise the temperature to 100-130℃, and carry out the in-situ coordination reaction at a constant temperature for 6-10 h. After the reaction is completed, cool to room temperature, centrifuge, wash, and vacuum dry to constant weight to obtain the MOF composite material. S3. Preparation of modified carrier: Polyisobutylene succinimide was added to toluene, stirred and dissolved, and then epichlorohydrin was added. The temperature was raised to 45-65℃ and stirred at a constant temperature for 2-4 hours. After the reaction was completed, toluene and unreacted epichlorohydrin were removed by distillation to obtain epoxy group modified polyisobutylene succinimide. S4. Preparation of lubricating oil dispersant: Add the modified carrier and base oil prepared in step S3 to the reaction vessel, heat to 80-100℃, stir until completely dissolved, add the MOF composite material prepared in step S2, ultrasonically disperse for 30-50 min, then add functional additives, heat to 110-140℃, stir at a constant temperature for 4-7 h, cool to room temperature after the reaction is completed, filter to remove impurities, and obtain the lubricating oil dispersant based on MOF composite material.

3. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: The zirconium salt is one or a mixture of two of zirconium chloride and zirconium oxychloride in any proportion, and the molar ratio of the zirconium salt to 2-aminoterephthalic acid is 1:1.2-1.

8.

4. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: The base oil is one or a mixture of two of PAO4 and PAO6 in any proportion.

5. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: In step S1, the volume ratio of ethanol to deionized water in the ethanol-deionized water mixed solution is 3-5:1, and the mass ratio of carbon nanotubes to aminosilane coupling agent KH-550 is 10:1.5-3.

0.

6. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: In step S2, the mass ratio of zirconium salt, 2-aminoterephthalic acid, and amino-grafted modified carbon nanotubes is 1:1.5-2.0:0.8-1.

5.

7. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: In step S3, the mass ratio of polyisobutylene succinimide to epichlorohydrin is 10:2.5-4.5, and the number average molecular weight of polyisobutylene succinimide is 1500-3500.

8. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: In step 4, the power of ultrasonic dispersion is 300-500W, and the rotation speed of constant temperature stirring is 300-500r / min.

9. The method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: In step S2, the washing process involves alternating washing with N,N-dimethylformamide and ethanol 3-5 times; in steps S1, S2, and S3, the vacuum drying temperature is 80-100℃ and the drying time is 8-12 hours.

10. A method for preparing a lubricating oil dispersant based on MOF composite materials according to claim 2, characterized in that: The antioxidant is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1-2, and the dispersant stabilizer is polyether dispersant stabilizer L64.

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