Bio-based lubricating oil composition with high oxidation stability and preparation method thereof

Abstract

The invention provides a bio-based lubricating oil composition with high oxidation stability and a preparation method thereof, and belongs to the technical field of bio-based lubricating oil. Functional base oil with hydroxyl is prepared from modified bio-based cardanol to serve as a network construction unit; the dynamic cross-linking agent is introduced and can be combined with the base oil through reversible ester exchange reaction at high temperature to form a dynamic three-dimensional network; a surface hydrophobic modified catalyst is introduced for catalytic decomposition of peroxide; a synergistic enhancement effect exists in the system: a polar micro-region formed by a dynamic network can selectively enrich harmful peroxides, and then the harmful peroxides are catalytically decomposed by a surface hydrophobically modified catalyst positioned in the network, so that the propagation rate of an oxidation chain reaction is reduced; meanwhile, due to the reversibility of the network, the lubricating oil can maintain necessary flowability while providing protection, and gelation is avoided.

Description

Technical Field

[0001] This invention belongs to the field of bio-based lubricant technology, and relates to a bio-based lubricant composition with high oxidation stability and its preparation method. Background Technology

[0002] With the deepening of the concept of sustainable development, the development of high-performance bio-based lubricants has become an important research direction in the field of lubrication technology. Bio-based ester lubricants, represented by vegetable oils, have attracted widespread attention due to their renewability and excellent biodegradability. However, the widespread application of these base oils still faces challenges posed by their inherent chemical structure. On the one hand, the ester bonds in their molecules are easily hydrolyzed at high temperatures and in the presence of trace amounts of water; on the other hand, the unsaturated double bonds prevalent in fatty acid chains make their oxidative stability weaker than that of traditional mineral oils, which to some extent limits their application under harsh operating conditions such as high temperature and long service life.

[0003] To improve the oxidation stability of bio-based lubricants, current technologies mainly rely on adding antioxidants. Currently, mainstream antioxidant technologies primarily use sacrificial additives such as hindered phenols and aromatic amines. These additives neutralize free radicals in the system through their own oxidation, operating on a stoichiometric basis. This means their protective capabilities gradually diminish over time; once depleted, lubricant oxidation accelerates dramatically, leading to a significant performance decline in the later stages of service. Furthermore, this passive protection mechanism based on random molecular collisions may be limited in its response efficiency and protective effectiveness against concentrated, high-intensity oxidation caused by metal catalysis or localized overheating. Therefore, exploring new antioxidant systems that transcend the traditional "sacrificial" model and develop longer-lasting, more efficient protective mechanisms is one of the key technological challenges driving the development of high-performance bio-based lubricants. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a bio-based lubricating oil composition with high oxidation stability and its preparation method. This application utilizes a functionalized base oil with hydroxyl groups prepared from modified bio-based cashew nut shells as a network building block; introduces a dynamic crosslinking agent that can reversibly bind to the base oil at high temperatures via transesterification to form a dynamic three-dimensional network; introduces a surface-hydrophobically modified catalyst for catalytic decomposition of peroxides; and exhibits a synergistic enhancement effect in the system: the polar microregions formed by the dynamic network can enrich harmful peroxides, which are then catalytically decomposed by the surface-hydrophobically modified catalyst located within the network, thereby reducing the propagation of the oxidation chain reaction and prolonging the induction period; simultaneously, the reversibility of this network enables the lubricating oil to maintain necessary fluidity while providing protection, preventing gelation.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a bio-based lubricating oil composition with high oxidation stability, the method comprising:

[0007] S1: Add Raney Ni catalyst to the ethanol dispersion of cashew nutmeg to obtain reaction solution A. Place reaction solution A in a high-pressure reactor, react, filter, and rotary evaporate to obtain preliminarily modified cashew nutmeg. Mix the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin to obtain a mixture. Add sodium hydroxide aqueous solution to obtain reaction solution B. React, wash, dry, and purify to obtain cashew nutmeg glycidyl ether. Mix cashew nutmeg glycidyl ether with glycerol, add p-toluenesulfonic acid to obtain reaction solution C. Stir the reaction to obtain the post-reaction solution. Cool to room temperature, add alkaline alumina powder, stir to adsorb, filter to obtain filtrate, and evaporate it through a thin film to obtain functionalized base oil.

[0008] S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide, and ethanol was added to obtain reaction solution D. After reaction, centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E. After stirring and reaction, centrifugation, washing and freeze-drying were performed to obtain a catalyst with hydrophobic surface modification.

[0009] S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F. The reaction solution F is refluxed until no anhydrous product is generated, rotary evaporated and vacuum dried to obtain dynamic crosslinking agent.

[0010] S4: Functionalized base oil is mixed with PAO4 (polyalphaolefin) and heated to obtain mixed base oil. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain the first mixture. A surface hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain concentrated mother liquor. The concentrated mother liquor is added to the first mixture to obtain the second mixture. Polyhexyl methacrylate and non-silicone antifoaming agent are added and stirred continuously. After cooling, a bio-based lubricating oil composition with high oxidation stability is obtained.

[0011] As a preferred technical solution of the present invention, in step S1, the mass-to-volume ratio of cashew phenol to ethanol in the cashew phenol ethanol dispersion is 1g:(5-10)mL, for example, it can be 1g:5.0mL, 1g:5.5mL, 1g:6.0mL, 1g:6.5mL, 1g:7.0mL, 1g:7.5mL, 1g:8.0mL, 1g:8.5mL, 1g:9.0mL, 1g:9.5mL or 1g:10.0mL, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0012] In some alternative embodiments, the mass ratio of the catalyst Raney Ni to cashew phenol is (1-2):100, for example, it can be 1.0:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100 or 2.0:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0013] In some optional embodiments, the hydrogen pressure of the reaction liquid A in the high-pressure reactor is 1-5 bar, for example, it can be 1.0 bar, 1.4 bar, 1.8 bar, 2.2 bar, 2.6 bar, 3.0 bar, 3.4 bar, 3.8 bar, 4.2 bar, 4.6 bar or 5.0 bar, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the reaction temperature of the reaction solution A in the high-pressure reactor is 40-80°C, for example, it can be 40°C, 44°C, 48°C, 52°C, 56°C, 60°C, 64°C, 68°C, 72°C, 76°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the reaction time of the reaction solution A in the high-pressure reactor is 4-8 hours, for example, 4.0 hours, 4.4 hours, 4.8 hours, 5.2 hours, 5.6 hours, 6.0 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours or 8.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the molar ratio of the preliminarily modified cashew phenol, tetrabutylammonium bromide, and epichlorohydrin is 1:0.02:(1.5-2), for example, it can be 1:0.02:1.50, 1:0.02:1.55, 1:0.02:1.60, 1:0.02:1.65, 1:0.02:1.70, 1:0.02:1.75, 1:0.02:1.80, 1:0.02:1.85, 1:0.02:1.90, 1:0.02:1.95, or 1:0.02:2.00, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0017] In some alternative embodiments, the mixture is added to an aqueous sodium hydroxide solution at 60-70°C to obtain reaction solution B. For example, it can be added at 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the concentration of the sodium hydroxide aqueous solution is 30-40 wt.%, for example, it can be 30 wt.%, 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%, 36 wt.%, 37 wt.%, 38 wt.%, 39 wt.%, or 40 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the molar ratio of sodium hydroxide to preliminarily modified cashew phenol in the reaction solution B is (1-1.1):1, for example, it can be 1.00:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1 or 1.10:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the reaction time of the reaction solution B is 4-6 hours, for example, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5.0 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, or 6.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the molar ratio of cashew phenol glycidyl ether to glycerol is 1:(0.5-0.7), for example, it can be 1:0.50, 1:0.52, 1:0.54, 1:0.56, 1:0.58, 1:0.60, 1:0.62, 1:0.64, 1:0.66, 1:0.68 or 1:0.70, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether is (0.5-1.5):100, for example, it can be 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1.0:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100 or 1.5:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the reaction temperature of the reaction liquid C is 100-120°C, for example, it can be 100°C, 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, 118°C or 120°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the reaction time of the reaction solution C is 2-4 hours, for example, it can be 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the amount of alkaline alumina powder added is 5-10% of the mass of the solution after reaction, for example, it can be 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5% or 10.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the stirring and adsorption time is 40-60 min, for example, it can be 40 min, 42 min, 44 min, 46 min, 48 min, 50 min, 52 min, 54 min, 56 min, 58 min or 60 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] As a preferred embodiment of the present invention, in step S2, the molar ratio of tetrakis(4-carboxyphenyl)porphyrin to manganese acetate tetrahydrate is 1:(1.5-3), for example, it can be 1:1.50, 1:1.65, 1:1.80, 1:1.95, 1:2.10, 1:2.25, 1:2.40, 1:2.55, 1:2.70, 1:2.85 or 1:3.00, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the concentration of tetrakis(4-carboxyphenyl)porphyrin in the reaction solution D is 5-10 mM, for example, it can be 5.0 mM, 5.5 mM, 6.0 mM, 6.5 mM, 7.0 mM, 7.5 mM, 8.0 mM, 8.5 mM, 9.0 mM, 9.5 mM or 10.0 mM, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the volume of ethanol is 10-20% of the volume of N,N-dimethylformamide, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the reaction temperature of the reaction solution D is 110-130°C, for example, 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the reaction time of the reaction solution D is 12-24 hours, for example, 12.0 hours, 13.2 hours, 14.4 hours, 15.6 hours, 16.8 hours, 18.0 hours, 19.2 hours, 20.4 hours, 21.6 hours, 22.8 hours, or 24.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the mass ratio of the octadecyltrichlorosilane to the nanoparticles is (0.5-1.5):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the molar ratio of triethylamine to octadecyltrichlorosilane is (0.5-1):1, for example, it can be 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1 or 1:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the reaction temperature of the reaction liquid E is 30-50°C, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the reaction time of the reaction solution E is 8-16 hours, for example, 8.0 hours, 8.8 hours, 9.6 hours, 10.4 hours, 11.2 hours, 12.0 hours, 12.8 hours, 13.6 hours, 14.4 hours, 15.2 hours or 16.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] As a preferred technical solution of the present invention, in step S3, the molar ratio of boric acid to 1,10-decanediol is 1:(0.7-0.9), for example, it can be 1:0.70, 1:0.72, 1:0.74, 1:0.76, 1:0.78, 1:0.80, 1:0.82, 1:0.84, 1:0.86, 1:0.88 or 1:0.90, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the molar ratio of boric acid to oleyl alcohol is 1:(0.3-0.5), for example, it can be 1:0.30, 1:0.32, 1:0.34, 1:0.36, 1:0.38, 1:0.40, 1:0.42, 1:0.44, 1:0.46, 1:0.48 or 1:0.50, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some alternative embodiments, the total mass of boric acid, 1,10-decanediol, and oleyl alcohol to toluene is in a mass-to-volume ratio of 1 g:(4-6) mL, for example, 1 g:4.0 mL, 1 g:4.2 mL, 1 g:4.4 mL, 1 g:4.6 mL, 1 g:4.8 mL, 1 g:5.0 mL, 1 g:5.2 mL, 1 g:5.4 mL, 1 g:5.6 mL, 1 g:5.8 mL, or 1 g:6.0 mL, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the temperature of the reflux reaction of the reaction solution F is 110-120°C, for example, it can be 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the vacuum drying temperature is 110-130°C, for example, it can be 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the vacuum drying time is 1-3 hours, for example, it can be 1.0 hours, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0042] As a preferred technical solution of the present invention, in step S4, the mass ratio of functionalized base oil to PAO4 in the mixed base oil is (6:4)-(7:3), for example, it can be 6:4, 6.1:3.9, 6.2:3.8, 6.3:3.7, 6.4:3.6, 6.5:3.5, 6.6:3.4, 6.7:3.3, 6.8:3.2, 6.9:3.1 or 7:3, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the functionalized base oil is mixed with PAO4 and then heated to a temperature of 60-80°C, for example, to 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0044] In some alternative embodiments, the mass ratio of the dynamic crosslinking agent to the first batch of mixed base oil in the first mixture is (1-3):100, for example, it can be 1.0:100, 1.2:100, 1.4:100, 1.6:100, 1.8:100, 2.0:100, 2.2:100, 2.4:100, 2.6:100, 2.8:100 or 3.0:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the mass ratio of the surface-hydrophobically modified catalyst to the second part of mixed base oil in the concentrated mother liquor is (0.2-0.8):100, for example, it can be 0.20:100, 0.26:100, 0.32:100, 0.38:100, 0.44:100, 0.50:100, 0.56:100, 0.62:100, 0.68:100, 0.74:100 or 0.80:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the mass ratio of the dynamic crosslinking agent to the surface hydrophobically modified catalyst in the second mixture is (2-5):1, for example, it can be 2.0:1, 2.3:1, 2.6:1, 2.9:1, 3.2:1, 3.5:1, 3.8:1, 4.1:1, 4.4:1, 4.7:1 or 5.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the stirring time after adding polyhexadecyl methacrylate and non-silicone antifoaming agent to the second mixture is 1-2 hours, for example, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, the amount of polyhexadecyl methacrylate fed is 2-5% of the mass of the second mixture, for example, it can be 2.0%, 2.3%, 2.6%, 2.9%, 3.2%, 3.5%, 3.8%, 4.1%, 4.4%, 4.7% or 5.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the amount of the non-silicone antifoaming agent added is 50-200 ppm of the mass of the second mixture, for example, it can be 50 ppm, 65 ppm, 80 ppm, 95 ppm, 110 ppm, 125 ppm, 140 ppm, 155 ppm, 170 ppm, 185 ppm or 200 ppm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] Secondly, the present invention provides a bio-based lubricating oil composition with high oxidation stability.

[0051] This application utilizes a functionalized base oil prepared by modifying bio-based cashew nut shells as the matrix and dynamic network building block of the entire lubrication system. First, through catalytic hydrogenation, the easily oxidized unsaturated double bonds on the cashew nut shell molecule's side chains are converted into chemically more stable saturated single bonds, enhancing the inherent antioxidant capacity of the base oil skeleton. Subsequently, an etherification reaction converts the phenolic hydroxyl groups of cashew nut shells into epoxy groups, serving as reaction sites for subsequent functionalization. Finally, glycerol is used to partially open the epoxy groups, introducing multiple hydroxyl functional groups at one end of the molecule. These hydroxyl groups serve as pre-defined reaction anchors, providing reversible binding sites for dynamic crosslinking agents in the subsequent lubricating oil working environment, forming the structural basis for the in-situ self-assembly behavior of the entire system.

[0052] This application introduces a surface-hydrophobically modified catalyst for the catalytic decomposition of harmful peroxides. The catalyst is a metal-organic framework nanoparticle with manganese ions as the metal center and porphyrin derivatives as organic ligands. The use of redox-active manganese ions and porphyrin ligands endows the nanoparticles with catalytic function. To ensure stable dispersion in non-polar base oils, long-chain alkyl groups are grafted onto its surface via a silanization reaction. This hydrophobic modification solves the interfacial compatibility problem between the nanomaterial and the oil matrix, enabling uniform dispersion of the surface-hydrophobically modified catalyst and thus providing long-lasting catalytic activity throughout the lubricating oil system.

[0053] This application introduces a dynamic crosslinking agent that responds to changes in the external environment, linking dispersed base oil molecules into a three-dimensional network. The multiple borate ester bonds within this molecular chain possess reversible chemical properties. When the lubricating oil temperature increases or local polarity increases, these borate ester bonds can react with the hydroxyl groups on the functionalized base oil molecules. This temporarily bridges individual base oil molecules, forming microregions enriched with polar species and a reversible network. The long alkoxy groups at the chain ends ensure their solubility in the base oil.

[0054] This application presents a synergistic antioxidant effect based on the enrichment of oxidation products by a dynamic network and the catalytic removal of these products by a surface-hydrophobically modified catalyst. The network formed by the self-assembly of the dynamic crosslinking agent and functionalized base oil at high temperature creates polar microdomains that selectively adsorb and enrich polar peroxides generated during oxidation. Secondly, the surface-hydrophobically modified catalyst is embedded in this network or enriched near the polar microdomains. The increased local concentration of peroxides due to enrichment enhances the removal efficiency of the surface-hydrophobically modified catalyst. The surface-hydrophobically modified catalyst catalytically decomposes the peroxides, thereby inhibiting the propagation of the oxidation chain reaction and prolonging the induction period. Furthermore, the transesterification reaction formed by the network in this system, along with the presence of water, creates a dynamic equilibrium, allowing the network to provide protection while recombinating under shear stress, maintaining the fluidity of the lubricating oil and preventing permanent gelation.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] This application utilizes a functionalized base oil prepared by modifying bio-based cashew nut shells as the matrix and dynamic network building block of the entire lubrication system. The inherent oxidative stability of the cashew nut shells is enhanced by catalytic hydrogenation of the side-chain double bonds; multiple hydroxyl groups are introduced at the molecular ends through etherification and glycerol ring-opening reactions. These hydroxyl groups serve as reversible reaction sites, binding with a dynamic crosslinking agent to provide the structural basis for in-situ self-assembly of the entire system.

[0057] This application introduces a surface-hydrophobically modified catalyst for the catalytic decomposition of harmful peroxides in lubricating oil. To address the dispersion problem in the non-polar oil phase, the surface of the hydrophobically modified catalyst is hydrophobically modified by grafting long alkyl chains, enabling it to be stably and uniformly dispersed in the base oil, thus allowing it to exert its catalytic and antioxidant functions for a long time throughout the entire lubrication system.

[0058] This application introduces a dynamic crosslinking agent that, upon temperature increase or localized polarity increase, reacts reversibly with the hydroxyl groups of the functionalized base oil through its borate ester bonds, thereby linking dispersed base oil molecules into a dynamic three-dimensional network. This crosslinking agent endows the lubricating oil system with self-adaptive capabilities. Simultaneously, the long alkoxy segments in its molecular structure ensure its solubility in the oil phase.

[0059] This application demonstrates a synergistic antioxidant effect. At high temperatures, self-assembly forms microdomains and a reversible network enriched with polar species. These polar microdomains selectively enrich and concentrate harmful polar peroxides generated during oxidation. Secondly, the surface-modified hydrophobic catalyst located within this network or microdomain can more efficiently catalyze the decomposition of peroxides due to the increased local peroxide concentration, thereby inhibiting the propagation of the oxidation chain reaction and prolonging the induction period. Furthermore, the reversibility of the network formation ensures that the lubricating oil maintains necessary fluidity while providing protection, preventing gelation.

[0060] The dynamic borate ester network in this application tends to reassemble after shearing or thermal oxidative disturbances via reversible borate bonds, promoting the recovery of microstructure and oil film carrying capacity. Simultaneously, the surface-modified hydrophobic catalyst acts as a catalytic node, helping to continuously scavenge reactive oxygen species and peroxides, slowing the accumulation of oxidation byproducts and metal surface deactivation, and supporting the re-adsorption and reconstruction of the boundary lubrication film. These two factors work synergistically to make the system more likely to maintain stable viscosity and interface protection under start-up, shutdown, and load fluctuation conditions, reducing the tendency for varnish and deposit formation, thereby extending service life and improving operational reliability. Detailed Implementation

[0061] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0062] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0063] Example 1

[0064] This embodiment provides a bio-based lubricating oil composition with high oxidation stability and its preparation method. The preparation method of the bio-based lubricating oil composition with high oxidation stability specifically includes the following steps:

[0065] S1: Raney Ni catalyst was added to an ethanol dispersion of cashew nutmeg to obtain reaction solution A, where the mass-to-volume ratio of cashew nutmeg to ethanol was 1 g:8 mL, and the mass ratio of Raney Ni catalyst to cashew nutmeg was 1.8:100. Reaction solution A was placed in a high-pressure reactor and reacted at a hydrogen pressure of 4 bar and 70°C for 7 h. After filtration and rotary evaporation, preliminarily modified cashew nutmeg was obtained. The preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin were mixed to obtain a mixture, where the molar ratio of the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin was 1:0.02:1.8. A 32 wt.% sodium hydroxide aqueous solution was added at 68°C to obtain reaction solution B, where the molar ratio of sodium hydroxide to preliminarily modified cashew nutmeg in reaction solution B was... The reaction mixture was prepared at a ratio of 1.08:1 and reacted for 5.5 h. After washing, drying, and purification, cashew phenol glycidyl ether was obtained. Cashew phenol glycidyl ether was mixed with glycerol at a molar ratio of 1:0.65, and p-toluenesulfonic acid was added to obtain reaction solution C, wherein the molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether was 1.2:100. The mixture was stirred at 115 °C for 3.5 h to obtain the reaction solution. After cooling to room temperature, alkaline alumina powder was added at a feed amount of 8% of the mass of the reaction solution. After stirring and adsorption for 55 min, the mixture was filtered to obtain the filtrate. The filtrate was then evaporated through a thin film to obtain the functionalized base oil.

[0066] S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide at a molar ratio of 1:2.5. Ethanol was added to obtain reaction solution D, in which the concentration of tetra(4-carboxyphenyl)porphyrin was 8 mM and the volume of ethanol was 12% of the volume of N,N-dimethylformamide. The reaction was carried out at 125 °C for 20 h. After centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E, in which the mass ratio of octadecyltrichlorosilane to nanoparticles was 1.2:1 and the molar ratio of triethylamine to octadecyltrichlorosilane was 0.8:1. The reaction was stirred at 45 °C for 14 h. After centrifugation, washing and freeze-drying, a surface-hydrophobically modified catalyst was obtained.

[0067] S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F, wherein the molar ratio of boric acid to 1,10-decanediol is 1:0.85, the molar ratio of boric acid to oleyl alcohol is 1:0.45, and the mass-volume ratio of the total mass of solute boric acid, 1,10-decanediol and oleyl alcohol to solvent toluene is 1 g:5.5 mL. Reaction solution F is refluxed at 118 °C until no anhydrous formation is generated, rotary evaporated, and vacuum dried at 115 °C for 2.5 h to obtain dynamic crosslinking agent;

[0068] S4: Functionalized base oil and PAO4 are mixed at a mass ratio of 7:3 and heated to 75°C. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain a first mixture. The mass ratio of the dynamic crosslinking agent to the first part of the mixed base oil in the first mixture is 2.5:100. A surface-hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain a concentrated mother liquor. The mass ratio of the surface-hydrophobic modified catalyst to the mixed base oil in the concentrated mother liquor is 0.6:100. The concentrated mother liquor is added to the first mixture to obtain a second mixture. The mass ratio of the dynamic crosslinking agent to the surface-hydrophobic modified catalyst in the second mixture is 4:1. Polyhexadecanyl methacrylate and non-silicone antifoaming agent are added and stirred for 1.8 hours. The amount of polyhexadecanyl methacrylate added is 4% of the mass of the second mixture, and the amount of non-silicone antifoaming agent added is 150 ppm of the mass of the second mixture. The mixture is cooled to obtain a bio-based lubricating oil composition with high oxidation stability.

[0069] Example 2

[0070] This embodiment provides a bio-based lubricating oil composition with high oxidation stability and its preparation method. The preparation method of the bio-based lubricating oil composition with high oxidation stability specifically includes the following steps:

[0071] S1: Adding Raney Ni catalyst to an ethanol dispersion of cashew nutmeg yields reaction solution A, where the mass-to-volume ratio of cashew nutmeg to ethanol is 1 g:5 mL, and the mass ratio of Raney Ni catalyst to cashew nutmeg is 1:100. Reaction solution A is placed in a high-pressure reactor and reacted at 40°C and 1 bar of hydrogen pressure for 4 hours. After filtration and rotary evaporation, preliminarily modified cashew nutmeg is obtained. The preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin are mixed to obtain a mixture, where the molar ratio of the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin is 1:0.02:1.5. Adding a 40 wt.% sodium hydroxide aqueous solution at 60°C yields reaction solution B, where the sodium hydroxide in reaction solution B reacts with the preliminarily modified cashew nutmeg... The reaction was carried out at a molar ratio of 1:1 for 4 hours. After washing, drying, and purification, cashew phenol glycidyl ether was obtained. Cashew phenol glycidyl ether and glycerol were mixed at a molar ratio of 1:0.5, and p-toluenesulfonic acid was added to obtain reaction solution C, wherein the molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether was 0.5:100. The reaction was stirred at 100℃ for 2 hours to obtain the reaction solution. After cooling to room temperature, alkaline alumina powder was added at a feed amount of 5% of the mass of the reaction solution. After stirring and adsorption for 40 minutes, the solution was filtered to obtain the filtrate. The filtrate was then evaporated through a thin film to obtain the functionalized base oil.

[0072] S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide at a molar ratio of 1:1.5. Ethanol was added to obtain reaction solution D, in which the concentration of tetra(4-carboxyphenyl)porphyrin was 5 mM and the volume of ethanol was 20% of the volume of N,N-dimethylformamide. The reaction was carried out at 110 °C for 12 h. After centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E, in which the mass ratio of octadecyltrichlorosilane to nanoparticles was 0.5:1 and the molar ratio of triethylamine to octadecyltrichlorosilane was 0.7:1. The reaction was stirred at 30 °C for 8 h. After centrifugation, washing and freeze-drying, a surface-hydrophobically modified catalyst was obtained.

[0073] S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F, wherein the molar ratio of boric acid to 1,10-decanediol is 1:0.7, the molar ratio of boric acid to oleyl alcohol is 1:0.3, and the mass-volume ratio of the total mass of solute boric acid, 1,10-decanediol and oleyl alcohol to solvent toluene is 1g:4mL. Reaction solution F is refluxed at 110℃ until no anhydrous formation is generated, rotary evaporated, and vacuum dried at 130℃ for 1h to obtain dynamic crosslinking agent;

[0074] S4: Functionalized base oil and PAO4 are mixed at a mass ratio of 6.5:3.5 and heated to 60°C. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain a first mixture. The mass ratio of the dynamic crosslinking agent to the first part of the mixed base oil in the first mixture is 1:100. A surface-hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain a concentrated mother liquor. The mass ratio of the surface-hydrophobic modified catalyst to the mixed base oil in the concentrated mother liquor is 0.2:100. The concentrated mother liquor is added to the first mixture to obtain a second mixture. The mass ratio of the dynamic crosslinking agent to the surface-hydrophobic modified catalyst in the second mixture is 2:1. Polyhexadecanyl methacrylate and non-silicone antifoaming agent are added and stirred for 1 hour. The amount of polyhexadecanyl methacrylate added is 2% of the mass of the second mixture, and the amount of non-silicone antifoaming agent added is 50 ppm of the mass of the second mixture. Cooling yields a bio-based lubricating oil composition with high oxidation stability.

[0075] Example 3

[0076] This embodiment provides a bio-based lubricating oil composition with high oxidation stability and its preparation method. The preparation method of the bio-based lubricating oil composition with high oxidation stability specifically includes the following steps:

[0077] S1: Raney Ni catalyst was added to an ethanol dispersion of cashew nutmeg to obtain reaction solution A, where the mass-to-volume ratio of cashew nutmeg to ethanol was 1 g:7 mL, and the mass ratio of Raney Ni catalyst to cashew nutmeg was 1.2:100. Reaction solution A was placed in a high-pressure reactor and reacted at a hydrogen pressure of 2 bar and 50°C for 5 h. After filtration and rotary evaporation, preliminarily modified cashew nutmeg was obtained. The preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin were mixed to obtain a mixture, where the molar ratio of the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin was 1:0.02:1.7. A 38 wt.% sodium hydroxide aqueous solution was added at 62°C to obtain reaction solution B, where the molar ratio of sodium hydroxide to preliminarily modified cashew nutmeg in reaction solution B was... The reaction mixture was prepared at a ratio of 1.02:1 and reacted for 4.5 h. After washing, drying, and purification, cashew phenol glycidyl ether was obtained. Cashew phenol glycidyl ether was mixed with glycerol at a molar ratio of 1:0.55, and p-toluenesulfonic acid was added to obtain reaction solution C, wherein the molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether was 0.8:100. The mixture was stirred at 105 °C for 2.5 h to obtain the reaction solution. After cooling to room temperature, alkaline alumina powder was added at a feed amount of 6% of the mass of the reaction solution. After stirring and adsorption for 45 min, the mixture was filtered to obtain the filtrate. The filtrate was then evaporated through a thin film to obtain the functionalized base oil.

[0078] S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide at a molar ratio of 1:2. Ethanol was added to obtain reaction solution D, in which the concentration of tetra(4-carboxyphenyl)porphyrin was 6 mM and the volume of ethanol was 18% of the volume of N,N-dimethylformamide. The reaction was carried out at 115 °C for 15 h. After centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E, in which the mass ratio of octadecyltrichlorosilane to nanoparticles was 0.8:1 and the molar ratio of triethylamine to octadecyltrichlorosilane was 0.5:1. The reaction was stirred at 35 °C for 10 h. After centrifugation, washing and freeze-drying, a surface-hydrophobically modified catalyst was obtained.

[0079] S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F, wherein the molar ratio of boric acid to 1,10-decanediol is 1:0.75, the molar ratio of boric acid to oleyl alcohol is 1:0.35, and the mass-volume ratio of the total mass of solutes boric acid, 1,10-decanediol and oleyl alcohol to solvent toluene is 1 g:4.5 mL. Reaction solution F is refluxed at 112 °C until no anhydrous formation is generated, rotary evaporated, and vacuum dried at 125 °C for 1.5 h to obtain dynamic crosslinking agent;

[0080] S4: Functionalized base oil and PAO4 are mixed at a mass ratio of 6:4 and heated to 65°C. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain a first mixture. The mass ratio of the dynamic crosslinking agent to the first part of the mixed base oil in the first mixture is 1.5:100. A surface-hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain a concentrated mother liquor. The mass ratio of the surface-hydrophobic modified catalyst to the mixed base oil in the concentrated mother liquor is 0.4:100. The concentrated mother liquor is added to the first mixture to obtain a second mixture. The mass ratio of the dynamic crosslinking agent to the surface-hydrophobic modified catalyst in the second mixture is 3:1. Polyhexadecanyl methacrylate and non-silicone antifoaming agent are added and stirred for 1.2 hours. The amount of polyhexadecanyl methacrylate added is 3% of the mass of the second mixture, and the amount of non-silicone antifoaming agent added is 80 ppm of the mass of the second mixture. The mixture is cooled to obtain a bio-based lubricating oil composition with high oxidation stability.

[0081] Example 4

[0082] This embodiment provides a bio-based lubricating oil composition with high oxidation stability and its preparation method. The preparation method of the bio-based lubricating oil composition with high oxidation stability specifically includes the following steps:

[0083] S1: Adding Raney Ni catalyst to an ethanol dispersion of cashew nutmeg yields reaction solution A, where the mass-to-volume ratio of cashew nutmeg to ethanol is 1 g:10 mL, and the mass ratio of Raney Ni catalyst to cashew nutmeg is 2:100. Reaction solution A is placed in a high-pressure reactor and reacted at 80°C and 5 bar hydrogen pressure for 8 hours. After filtration and rotary evaporation, preliminarily modified cashew nutmeg is obtained. The preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin are mixed to obtain a mixture, where the molar ratio of the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin is 1:0.02:2. Adding a 30 wt.% sodium hydroxide aqueous solution at 70°C yields reaction solution B, where the molar ratio of sodium hydroxide to preliminarily modified cashew nutmeg in reaction solution B is... The ratio of cashew phenol glycidyl ether to glycerol was 1.1:1, and the mixture was reacted for 6 hours. After washing, drying, and purification, cashew phenol glycidyl ether was obtained. Cashew phenol glycidyl ether was mixed with glycerol at a molar ratio of 1:0.7, and p-toluenesulfonic acid was added to obtain reaction solution C, wherein the molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether was 1.5:100. The mixture was stirred at 120°C for 4 hours to obtain the reaction solution. After cooling to room temperature, alkaline alumina powder at a feed amount of 10% of the mass of the reaction solution was added. After stirring and adsorption for 60 minutes, the mixture was filtered to obtain the filtrate. The filtrate was then evaporated through a thin film to obtain the functionalized base oil.

[0084] S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide at a molar ratio of 1:3. Ethanol was added to obtain reaction solution D, in which the concentration of tetra(4-carboxyphenyl)porphyrin was 10 mM and the volume of ethanol was 10% of the volume of N,N-dimethylformamide. The reaction was carried out at 130 °C for 24 h. After centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E, in which the mass ratio of octadecyltrichlorosilane to nanoparticles was 1.5:1 and the molar ratio of triethylamine to octadecyltrichlorosilane was 1:1. The reaction was stirred at 50 °C for 16 h. After centrifugation, washing and freeze-drying, a surface-hydrophobically modified catalyst was obtained.

[0085] S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F, wherein the molar ratio of boric acid to 1,10-decanediol is 1:0.9, the molar ratio of boric acid to oleyl alcohol is 1:0.5, and the mass-volume ratio of the total mass of solute boric acid, 1,10-decanediol and oleyl alcohol to solvent toluene is 1g:6mL. Reaction solution F is refluxed at 120℃ until no anhydrous formation is generated, rotary evaporated, and vacuum dried at 110℃ for 3h to obtain dynamic crosslinking agent;

[0086] S4: Functionalized base oil and PAO4 are mixed at a mass ratio of 6.8:3.2 and heated to 80°C. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain a first mixture. The mass ratio of the dynamic crosslinking agent to the first part of the mixed base oil in the first mixture is 3:100. A surface-hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain a concentrated mother liquor. The mass ratio of the surface-hydrophobic modified catalyst to the mixed base oil in the concentrated mother liquor is 0.8:100. The concentrated mother liquor is added to the first mixture to obtain a second mixture. The mass ratio of the dynamic crosslinking agent to the surface-hydrophobic modified catalyst in the second mixture is 5:1. Polyhexadecanyl methacrylate and a non-silicone antifoaming agent are added and stirred for 2 hours. The amount of polyhexadecanyl methacrylate added is 5% of the mass of the second mixture, and the amount of the non-silicone antifoaming agent added is 200 ppm of the mass of the second mixture. The mixture is cooled to obtain a bio-based lubricating oil composition with high oxidation stability.

[0087] Comparative Example 1

[0088] This comparative example provides a bio-based lubricating oil composition with high oxidation stability. The difference from Example 1 is that no dynamic crosslinking agent is added in S4, while the other operating steps and process parameters are exactly the same as in Example 1.

[0089] Comparative Example 2

[0090] This comparative example provides a bio-based lubricating oil composition with high oxidation stability. The difference from Example 1 is that no surface-hydrophobic modified catalyst is added in S4, while the other operating steps and process parameters are exactly the same as in Example 1.

[0091] Comparative Example 3

[0092] This comparative example provides a bio-based lubricant composition with high oxidation stability. The difference from Example 1 is that cashew phenol glycidyl ether is used to replace the functionalized base oil. All other operating steps and process parameters are exactly the same as in Example 1.

[0093] Comparative Example 4

[0094] This comparative example provides a bio-based lubricant composition with high oxidation stability. The difference from Example 1 is that nano-silica, which is also hydrophobically modified with octadecyltrichlorosilane, is used instead of the surface-hydrophobically modified catalyst. Other operating steps and process parameters are exactly the same as in Example 1.

[0095] The performance of the bio-based lubricating oil compositions with high oxidation stability in Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0096] The oxidation induction time of the sample was tested according to ASTM D2272;

[0097] The sample was aged by forced gas oxidation at 150°C for 100 hours, and then its peroxide value was tested according to ASTM D3703.

[0098] According to ASTM D4683, the high-temperature high-shear viscosity of the sample at 150°C was tested.

[0099] The test results are shown in Table 1.

[0100] Table 1. Performance test results of bio-based lubricating oil compositions with high oxidation stability in Examples 1-4 and Comparative Examples 1-4

[0101]

[0102] As shown in Table 1, the test results of Example 1 and Comparative Example 1 indicate that without the addition of a dynamic crosslinking agent, the system in S4 cannot form micro-regions and a reversible network structure enriched with polar species at high temperatures. Lacking the targeted enrichment of oxidation products by this network, the surface-hydrophobically modified catalyst mainly relies on free molecular diffusion and collision, resulting in decreased efficiency, shortened oxidation induction time, and increased peroxide value after aging due to insufficient catalytic efficiency. Simultaneously, due to the lack of a network structure to enhance the oil film, the viscosity of this sample decreases under high-temperature and high-shear conditions, indicating insufficient high-temperature oil film strength.

[0103] As shown in Table 1, the test results of Example 1 and Comparative Example 2 reveal that while the system in S4, without the addition of a surface-hydrophobic modified catalyst, can form micro-regions and a reversible network enriched with polar species, it lacks a core functional unit for efficiently removing oxidation products. The peroxides enriched in the dynamic network accumulate due to their inability to be decomposed in time, leading to an increase in peroxide value after aging, accelerating the overall oxidation of the oil, and reducing the oxidation induction time. The relatively small change in high-temperature, high-shear viscosity verifies the formation of the network structure.

[0104] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that when cashew phenol glycidyl ether is used to replace the functionalized base oil, the lack of reactive hydroxyl sites in its molecular structure prevents the dynamic crosslinking agent from binding to it via transesterification, thus hindering the formation of a dynamic network. This results in the failure of the system's synergistic antioxidant effect, leading to a decrease in its oxidation induction time. Simultaneously, the lack of network enrichment reduces the catalytic efficiency of the hydrophobically modified catalyst, increasing the accumulation of peroxides after aging. The high-temperature high-shear viscosity decreases, indicating insufficient high-temperature oil film strength due to the failure of the dynamic network to form.

[0105] As shown in Table 1, the test results of Example 1 and Comparative Example 4 reveal that while replacing the surface-hydrophobically modified catalyst with nano-silica modified with octadecyltrichlorosilane can form micro-regions and a reversible network enriched with polar species, the highly active peroxides enriched in the network cannot be effectively removed and accumulate in large quantities because nano-silica lacks the ability to catalyze the decomposition of peroxides. These accumulated peroxides accelerate the overall degradation of the oil, leading to a decrease in its oxidation induction time and an increase in its peroxide value after aging. The viscosity at high temperature and high shear remains relatively unchanged, indicating that the dynamic network structure forms and enhances the oil film.

[0106] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a bio-based lubricating oil composition with high oxidation stability, characterized in that, The preparation method includes: S1: Add Raney Ni catalyst to the ethanol dispersion of cashew nutmeg to obtain reaction solution A. Place reaction solution A in a high-pressure reactor, react, filter, and rotary evaporate to obtain preliminarily modified cashew nutmeg. Mix the preliminarily modified cashew nutmeg, tetrabutylammonium bromide, and epichlorohydrin to obtain a mixture. Add sodium hydroxide aqueous solution to obtain reaction solution B. React, wash, dry, and purify to obtain cashew nutmeg glycidyl ether. Mix cashew nutmeg glycidyl ether with glycerol and add p-toluenesulfonic acid to obtain reaction solution C. Stir the reaction to obtain the post-reaction solution. Cool to room temperature, add alkaline alumina powder, stir to adsorb, filter to obtain filtrate, and evaporate it through a thin film to obtain functionalized base oil. S2: Tetra(4-carboxyphenyl)porphyrin and manganese acetate tetrahydrate were dispersed in N,N-dimethylformamide, and ethanol was added to obtain reaction solution D. After reaction, centrifugation and washing, nanoparticles were obtained. The nanoparticles were dispersed in toluene, and octadecyltrichlorosilane and triethylamine were added to obtain reaction solution E. After stirring and reaction, centrifugation, washing and freeze-drying were performed to obtain a catalyst with hydrophobic surface modification. S3: Boric acid, 1,10-decanediol and oleyl alcohol are mixed in toluene to obtain reaction solution F. The reaction solution F is refluxed until no anhydrous product is generated, rotary evaporated and vacuum dried to obtain dynamic crosslinking agent. S4: Functionalized base oil and PAO4 are mixed and heated to obtain mixed base oil. The mixed base oil is divided into two parts. A dynamic crosslinking agent is added to the first part of the mixed base oil and stirred to obtain the first mixture. A surface-hydrophobic modified catalyst is mixed with the second part of the mixed base oil and ultrasonically treated to obtain concentrated mother liquor. The concentrated mother liquor is added to the first mixture to obtain the second mixture. Polyhexyl methacrylate and non-silicone antifoaming agent are added and stirred continuously. After cooling, a bio-based lubricating oil composition with high oxidation stability is obtained.

2. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S1: The mass-to-volume ratio of cashew phenol to ethanol in the ethanol dispersion is 1 g:(5-10) mL. The mass ratio of the catalyst Raney Ni to cashew phenol is (1-2):

100.

3. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S1: The molar ratio of the preliminarily modified cashew phenol, tetrabutylammonium bromide and epichlorohydrin is 1:0.02:(1.5-2); The molar ratio of sodium hydroxide to preliminarily modified cashew phenol in the reaction solution B is (1-1.1):

1.

4. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S1: The molar ratio of cashew phenol glycidyl ether to glycerol is 1:(0.5-0.7); The molar ratio of p-toluenesulfonic acid to cashew phenol glycidyl ether is (0.5-1.5):100; The amount of alkaline alumina powder added is 5-10% of the mass of the solution after the reaction.

5. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S2: The molar ratio of the tetra(4-carboxyphenyl)porphyrin to manganese acetate tetrahydrate is 1:(1.5-3); The concentration of tetrakis(4-carboxyphenyl)porphyrin in the reaction solution D is 5-10 mM; The volume of the ethanol is 10-20% of the volume of N,N-dimethylformamide.

6. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S2: The mass ratio of octadecyltrichlorosilane to nanoparticles is (0.5-1.5):1; The molar ratio of triethylamine to octadecyltrichlorosilane is (0.5-1):

1.

7. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S3: The molar ratio of boric acid to 1,10-decanediol is 1:(0.7-0.9); The molar ratio of boric acid to oleyl alcohol is 1:(0.3-0.5); The total mass of boric acid, 1,10-decanediol and oleyl alcohol is in a mass-to-volume ratio of 1 g to (4-6) mL of toluene.

8. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S4: The mass ratio of functionalized base oil to PAO4 in the blended base oil is (6:4)-(7:3); The mass ratio of the dynamic crosslinking agent to the first batch of mixed base oil in the first mixture is (1-3):100; The mass ratio of the surface-hydrophobically modified catalyst in the concentrated mother liquor to the second mixed base oil is (0.2-0.8):

100.

9. The method for preparing a bio-based lubricating oil composition with high oxidation stability according to claim 1, characterized in that, In S4: The mass ratio of the dynamic crosslinking agent to the surface hydrophobically modified catalyst in the second mixture is (2-5):1; The amount of polyhexadecyl methacrylate added is 2-5% of the mass of the second mixture; The amount of the non-silicone antifoaming agent added is 50-200 ppm of the mass of the second mixture.

10. A bio-based lubricating oil composition with high oxidation stability prepared by the preparation method according to any one of claims 1-9.

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