Efficient synthesis and preparation process of PAO-XHVI composite base oil

Abstract

The invention relates to the technical field of lubricating oil preparation, and particularly discloses an efficient synthesis and preparation process of PAO-XHVI composite base oil, which comprises the following steps: S1, mixing C10-C14 straight-chain alpha-olefin with 1-3mo% of conjugated butadiene monomer to obtain a premixed monomer; s2, obtaining a crude PAO system; s3, a high-purity PAO component is obtained; s4, obtaining an XHVI polymer; s5, obtaining primary compound oil; s6, performing defoaming and microfiltration on the primary compound oil, and adding an antioxidant and a friction modifier to obtain final PAO-XHVI compound base oil; a trace amount of conjugated butadiene unit is introduced into a PAO main chain, and a coupling modified high viscosity index polymer (XHVI) is adopted in a compounding stage to form a dual viscosity regulation and control network. The PAO chain segment provides basic lubricating viscosity and low-temperature fluidity; the highly branched and compatible structure of the XHVI polymer can effectively maintain the oil film thickness at high temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lubricating oil preparation, and particularly relates to a high-efficiency synthesis preparation process of PAO-XHVI composite base oil. BACKGROUND

[0002] In the technical field of lubricating oil base oil, there are three core bottlenecks in the traditional synthesis base oil system, which seriously restrict the performance of high-end lubricating products under extreme working conditions. First, the viscosity-temperature response limitation of single-component base oil is significant: although conventional PAO (poly-alpha-olefin) has excellent low-temperature fluidity and oxidation stability, its high molecular chain structure regularity easily leads to viscosity attenuation in high-temperature environments, making it difficult to meet the dual requirements of-40℃ extremely cold starting and 150℃ or higher high-temperature working conditions; and although the traditional XHVI (ultra-high viscosity index) polymer realizes high-temperature oil film retention through highly branched structures, the molecular motion ability suddenly decreases under extremely low-temperature conditions, resulting in a sudden increase in low-temperature viscosity. This contradiction makes the traditional composite base oil always have a performance breakpoint in cross-temperature domain applications.

[0003] And there are technical shortcomings in deep refining and antioxidant systems. The traditional PAO hydrogenation process uses a single metal molybdenum sulfide catalyst, which is difficult to completely saturate residual double bonds below 260℃, resulting in a free radical generation rate of the base oil of 0.8x10^-3 / min level, and an oxidation induction period of less than 80 hours. The thermal oxidation stability of XHVI polymer is more limited by its branched structure, and the oxidation chain scission rate in the environment above 180℃ is 30-50% higher than that of PAO, which greatly shortens the service life of the traditional composite base oil in high-temperature application scenarios such as turbocharged engines.

[0004] To this end, the inventors propose a high-efficiency synthesis preparation process of PAO-XHVI composite base oil to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a high-efficiency synthesis preparation process of PAO-XHVI composite base oil to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The high-efficiency synthesis preparation process of PAO-XHVI composite base oil comprises the following steps:

[0008] S1, mixing C10-C14 linear alpha-olefins with 1-3 mol% conjugated butadiene monomers in a molar ratio of 98:2 to 95:5, and obtaining a premixed monomer after refining;

[0009] S2, ultrasonic-assisted fixed-bed polymerization of the pre-mixed monomers under the action of a molybdenum-chromium dual active site catalyst on a γ-Al2O3 carrier to obtain a crude PAO system;

[0010] S3, hydrogenation treatment and vacuum rectification refining of the crude PAO system to obtain a high-purity PAO component;

[0011] S4, polymerization of acrylate monomers initiated by a caprolactam skeleton and silane coupling modification of end groups to obtain an XHVI polymer;

[0012] S5, on-line mixing of the high-purity PAO component and the XHVI polymer at a mass ratio of 95:5 to 85:15 under high shear to obtain a preliminary composite oil;

[0013] S6, defoaming, microfiltration, and addition of antioxidants and friction modifiers to the preliminary composite oil to obtain a final PAO-XHVI composite base oil.

[0014] Preferably, the ultrasonic frequency of the ultrasonic-assisted polymerization in step S2 is 20-25 kHz, the power density is 0.5-1 W / mL, the polymerization temperature is 120-140℃, and the pressure is 2-3 MPa.

[0015] Preferably, the hydrogenation treatment in step S3 uses a molybdenum-ruthenium bimetallic catalyst under conditions of 5 MPa, 280-300℃, H2 / oil volume ratio 1000:1, and rectification vacuum degree <1 kPa.

[0016] Preferably, the acrylate monomers in step S4 are methyl methacrylate or butyl acrylate, the polymerization temperature is 60-80℃, the reaction conversion rate is >95%, and the silane coupling agent used is γ-methoxypropyl silane.

[0017] Preferably, the shear rate of the high shear mixing in step S5 is >10,000 s -1 , and the mixing temperature is controlled at 80-100℃.

[0018] Preferably, in step S6, the defoaming is performed by standing under vacuum for 30 min, and the microfiltration uses 320 μm and 100 μm filter screens in sequence.

[0019] Preferably, in step S6, 0.05-0.2 wt% of a phenolic antioxidant, 0.01-0.05 wt% of a phosphate extreme pressure agent, and 0.1-0.3 wt% of an emulsifying dispersant are also added on-line to improve the antioxidant performance and low-temperature fluidity of the finished product.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The present application forms a double viscosity regulation network by introducing trace conjugated butadiene units into the PAO backbone and using coupling modified high viscosity index polymer (XHVI) in the compounding stage. On the one hand, the PAO segment provides the basic lubricating viscosity and low temperature fluidity; on the other hand, the highly branched and compatible structure of the XHVI polymer can effectively maintain the oil film thickness at high temperature, so as to achieve balanced operation in a wide temperature range and realize more gentle viscosity change.

[0022] (2) The present application finely controls the branching degree of the PAO segment, combined with the silane modification of the XHVI end group, inhibits the crystallization tendency of the low molecular weight component, so that the base oil can still maintain good molecular motion ability in extremely low temperature environment, significantly improves the inversion temperature and flow point of the oil product, and provides a theoretical guarantee for the reliable start of the engine or equipment in cold climate.

[0023] (3) The present application uses two-stage deep refining and hydrogenation treatment, which can maximize the removal of unsaturated residues and trace impurities, and reduce the free radical generation rate of the oil product at the molecular level. At the same time, the branched skeleton of the XHVI polymer itself is resistant to oxidation, and its network structure is not easy to be oxidized and broken, which macroscopically improves the oxidation induction period and thermal oxidation stability of the whole oil product. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The present application is a high-efficiency synthesis process flow chart of PAO-XHVI composite base oil. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0026] Example 1:

[0027] Please refer to Figure 1 The high-efficiency preparation process of PAO-XHVI composite base oil (taking C12α-olefin as the main raw material)

[0028] Firstly, high-purity C12α-olefin is selected as the main raw material, and 3% conjugated butadiene is added. After drying with molecular sieves, the water content is ≤10 ppm, and a premixed monomer is prepared;

[0029] Further, the raw material composition: C12α-olefin (99.5% purity), copolymerization monomer butadiene (99.9% purity, provided by gas cylinder);

[0030] Drying method: 5A molecular sieve drying tower, ambient temperature tower adsorption treatment time ≥ 4h;

[0031] The target moisture content was verified by Karl Fischer moisture meter to be ≤10ppm.

[0032] Subsequently, a fixed bed reactor loaded with γ-Al2O3 supported molybdenum-chromium bimetallic catalyst was used for polymerization. An ultrasonic field (frequency 22 kHz, power density 0.8 W / mL) was introduced during the reaction, the reaction temperature was controlled at 135℃, the pressure was 2.5 MPa, and the reaction time was about 3 hours to obtain a crude polymerization product;

[0033] Further, a polymerization reaction system was used:

[0034] The equipment was a continuous fixed bed polymerization reactor (inner diameter 60 mm, height 1.2 m);

[0035] The filler was γ-Al2O3 supported Mo-Cr bimetallic catalyst with a specific surface area of 210 m 2 / g;

[0036] The ultrasonic device was an ultrasonic probe arranged around, with a frequency of 22 kHz and a power density of 0.8 W / mL (Branson ultrasonic module);

[0037] Reaction parameters:

[0038] Temperature: 135℃ (thermocouple automatic control); pressure: 2.5 MPa (inlet pressure control valve); residence time: 3 hours; product collection: received in an autoclave to obtain a crude PAO product.

[0039] After the crude PAO system was treated by molybdenum-ruthenium bimetallic catalyst hydrogenation (temperature 280℃, pressure 5 MPa, H2 / oil volume ratio 1000:1), it was subjected to distillation treatment in a vacuum rectifying column, with the column top temperature controlled at 250℃, the column bottom temperature at 320℃, and the vacuum degree ≤1 kPa, to finally obtain pure PAO components;

[0040] Further, hydrogenation and fractionation:

[0041] Equipment: tubular hydrogenation reactor (with internal heating device);

[0042] Rectifying column (column height 4 m, column diameter 80 mm, 30 layers of sieve plates);

[0043] Catalyst: sulfided Mo-Ru (0.2wt%, presulfided);

[0044] Hydrogenation conditions:

[0045] Temperature: 280℃; pressure: 5 MPa; hydrogen / oil ratio: 1000:1 (volume ratio);

[0046] Fractionation parameters:

[0047] Vacuum: 0.9 kPa; overhead temperature: 250 °C;

[0048] Product: high purity PAO component (yield ~ 89%).

[0049] Meanwhile, with caprolactam as the initiation base, methyl methacrylate monomer was added, and XHVI polymer was synthesized under the action of dicumyl peroxide at 60 °C for 6 hours. Subsequently, end group modification was performed using γ-methoxypropyl silane to obtain stable XHVI polymer;

[0050] Further, XHVI synthesis and modification:

[0051] Reaction system:

[0052] Raw materials: methyl methacrylate (MMA), caprolactam, initiator: dicumyl peroxide;

[0053] Molar ratio: MMA: caprolactam = 10:1;

[0054] Reaction device: three-necked flask, mechanical stirring + condensation reflux device;

[0055] Reaction parameters: temperature: 60 °C; time: 6 hours;

[0056] Silane capping: 0.5 wt% of γ-methoxypropyl silane was added, and the reaction was continued for 2 hours;

[0057] Product: structurally regular modified XHVI polymer.

[0058] The prepared high purity PAO component and XHVI polymer were mixed online at a mass ratio of 90:10 under the conditions of high shear rate (12,000 s -1 , high temperature (90 °C), to obtain a preliminary composite E. The composite was further degassed by vacuum standing for 20 minutes, and microfiltration treatment was performed through 320 μm and 100 μm filter screens in sequence;

[0059] Further, shear mixing:

[0060] Equipment: high-speed shear mixer (IKA Ultra-Turrax T50);

[0061] Mixing parameters:

[0062] Proportion: PAO: CXHVI = 90:10 (wt%);

[0063] Shear rate: 12,000 s -1Temperature: 90℃, Time: 15min

[0064] Deaeration + filtration:

[0065] Vacuum: -0.09MPa, Time: 20min

[0066] Filter: 320μm + 100μm double-stage stainless steel filter cartridge

[0067] Finally, 0.1wt% BHT antioxidant, 0.02wt% phosphate extreme pressure agent and 0.2wt% emulsifying dispersant were added in proportion to obtain the final composite base oil product;

[0068] Further, the additive addition formula composition:

[0069] BHT antioxidant: 0.1wt%, TPP phosphate: 0.02wt%, non-ionic emulsifier: 0.2wt%;

[0070] Stirring conditions: constant temperature stirring at 75℃ for 30min to ensure uniform dissolution.

[0071] Example Two:

[0072] Efficient preparation process of PAO-XHVI composite base oil for wide temperature range applications (C10-C14 α-olefin mixture)

[0073] In this example, C10, C12 and C14 α-olefins were mixed in a molar ratio of 2:5:3, and 4% butadiene was added. After the same drying and refining treatment, a premixed monomer was obtained. The drying method and equipment were the same as in Example One.

[0074] The premixed monomer was introduced into a fixed bed reactor containing a γ-Al2O3 supported Mo-Cr catalyst, and polymerization was carried out under the condition of 25kHz ultrasonic excitation, with a power density of 1.0W / mL, a reaction temperature of 125℃, a pressure of 3.0MPa, and a continuous reaction time of 4 hours, to generate a crude PAO product;

[0075] Further, the equipment and catalyst: the same reactor as in Example One, catalyst Mo-Cr;

[0076] Ultrasonic conditions:

[0077] Frequency: 25kHz, Power density: 1.0W / mL

[0078] Reaction temperature and pressure:

[0079] Temperature: 125℃, Pressure: 3.0MPa, Residence time: 4 hours, to generate a crude polymer.

[0080] The obtained crude PAO product was hydrogenated at 300°C and 5.5 MPa, and then subjected to vacuum rectification at 0.8 kPa to obtain a PAO component with high viscosity index;

[0081] Hydrogenation + fractionation:

[0082] Temperature: 300°C, pressure: 5.5 MPa;

[0083] Vacuum rectification: 240°C at the top of the column, vacuum degree 0.8 kPa, to obtain a PAO component.

[0084] As for the synthesis of XHVI, methyl methacrylate and butyl acrylate were copolymerized at a mass ratio of 7:3, caprolactam was added as an initiator, and the polymerization was carried out at 60°C for 6 hours, and then terminated with γ-methoxypropyl triethoxysilane for 2 hours to form a structured XHVI polymer;

[0085] Further, XHVI copolymerization + termination:

[0086] Monomer ratio: MMA: butyl ester = 7:3

[0087] Initiator: dicumyl peroxide;

[0088] Silane terminating agent: γ-methoxypropyl triethoxysilane;

[0089] Reaction time and temperature: copolymerization for 6 hours, termination for 2 hours, temperature 60°C;

[0090] XHVI component was obtained.

[0091] In the mixing process, PAO and XHVI were uniformly mixed at a mass ratio of 85:15, a shear rate of 15,000 s -1 , 95°C, to form a composite oil, which was vacuum degassed and double micro-filtered, and then 0.15% BHT, 0.03% ZnDDP and 0.2% polyether emulsifier were added, and the mixture was stirred at 75°C for 40 minutes to obtain a composite base oil;

[0092] Further, mixing equipment and method: same as Example 1

[0093] Ratio: PAO: XHVI = 85:15 (wt%);

[0094] Shear rate: 15000 s -1 ;

[0095] Temperature and time: 95°C, shear for 20 minutes.

[0096] Comparative example: traditional PAO 4 preparation method:

[0097] The comparative group selects the same batch of C12 alpha-olefin as raw material, does not add comonomer, uses traditional Ziegler-Natta catalyst polymerization, does not introduce ultrasonic field, reaction temperature is 150 DEG C, pressure is 2.0 MPa. After polymerization, general hydrogenation and rectification treatment are carried out, and no XHVI component is added, and the final product is traditional PAO 4 base oil.

[0098] The PAO 4 base oils prepared in the above embodiment one, embodiment two and comparative example are subjected to the following tests: one, sample preparation:

[0099] Sample number:

[0100] Sample A: PAO-XHVI composite base oil obtained in embodiment one;

[0101] Sample B: PAO-XHVI composite base oil obtained in embodiment two;

[0102] Sample C: traditional PAO 4 base oil in comparative example;

[0103] Pretreatment:

[0104] Each sample is placed in an 80 DEG C oil bath for constant temperature defoaming for 30 min;

[0105] Stand at room temperature for 15 min, remove residual bubbles;

[0106] The samples are respectively packed in clean test bottles (capacity 50 mL), and are sealed for standby use.

[0107] Two, the performance test steps are shown in the following table 1:

[0108] Table 1:

[0109]

[0110]

[0111] Note: Before all tests, the instruments are calibrated according to the standard process, and the standard control oil is used for verification and qualification.

[0112] Three, the test results are shown in the following table 2:

[0113] Table 2:

[0114]

[0115] From table 2, it can be seen that:

[0116] The viscosity index is significantly improved: sample A is improved by 28 VI points compared with traditional PAO 4, and sample B is improved by 35 VI points;

[0117] Low temperature fluidity optimization: pour point decreased by 9℃ and 6℃ respectively, which helps to start in extremely cold environment;

[0118] Anti-wear and stability enhancement: four-ball wear scar diameter reduced by about 16-20%, PDSC induction period extended by more than 50%.

[0119] From the above, the above tests fully verify the comprehensive advantages of PAO-XHVI composite base oil in viscosity-temperature performance, anti-wear and oxidation stability;

[0120] By introducing trace conjugated butadiene units into the PAO backbone and using coupling modified high viscosity index polymer (XHVI) in the compounding stage, a double viscosity regulation network is formed. On the one hand, the PAO segment provides the basic lubricating viscosity and low temperature fluidity; on the other hand, the highly branched and compatible structure of XHVI polymer can effectively maintain the oil film thickness at high temperature, so as to balance the operation in a wide temperature range and realize a more gentle viscosity change.

[0121] In this method, the branching degree of PAO segment is finely controlled, combined with the silane modification of XHVI end group, which inhibits the crystallization tendency of low molecular weight components, so that the base oil can still maintain good molecular motion ability in extremely low temperature environment, significantly improves the inversion temperature and flow point of the oil, and provides a theoretical guarantee for the reliable start of the engine or equipment in cold climate.

[0122] Two-stage deep refining and hydrogenation treatment can maximize the removal of unsaturated residues and trace impurities, and reduce the free radical generation rate of the oil at the molecular level. At the same time, the XHVI polymer itself contains an oxidation-resistant branched skeleton, and its network structure is not easy to be oxidized and broken, which improves the oxidation induction period and thermal oxidation stability of the whole oil from a macroscopic point of view.

[0123] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency synthetic preparation process of PAO-XHVI composite base oil, characterized in that, The method comprises the following steps: S1, mixing C10-C14 linear α-olefin with 1-3 mol% conjugated butadiene monomer at a molar ratio of 98:2-95:5, and obtaining premixed monomers after refining; S2, ultrasonic-assisted fixed bed polymerization of the premixed monomers under the action of a molybdenum-chromium dual active site catalyst on a γ-Al2O3 carrier to obtain a crude PAO system; S3, hydrogenation treatment and vacuum rectification refining of the crude PAO system to obtain a high-purity PAO component; S4, polymerization of an acrylate monomer initiated by a caprolactam skeleton and silane coupling modification of an end group to obtain an XHVI polymer; S5, online mixing of the high-purity PAO component and the XHVI polymer at a mass ratio of 95:5-85:15 under high shear conditions to obtain a preliminary composite oil; S6, defoaming, microfiltration, and addition of antioxidants and friction modifiers to the preliminary composite oil to obtain a final PAO-XHVI composite base oil.

2. The process for the efficient synthesis of PAO-X HVI complex base oil as claimed in claim 1, wherein: The ultrasonic frequency of the ultrasonic-assisted polymerization in step S2 is 20-25 kHz, the power density is 0.5-1 W / mL, the polymerization temperature is 120-140℃, and the pressure is 2-3 MPa.

3. The process for the efficient synthesis of PAO-X HVI composite base oil as claimed in claim 1, wherein: The hydrogenation treatment in step S3 uses a molybdenum sulfide-ruthenium bimetallic catalyst under the conditions of 5 MPa, 280-300℃, H2 / oil volume ratio 1000:1, and a distillation vacuum degree <1 kPa.

4. The process for the efficient synthesis of PAO-X HVI composite base oil as claimed in claim 1, wherein: The acrylate monomer in step S4 is methyl methacrylate or butyl acrylate, the polymerization temperature is 60-80℃, the reaction conversion rate is >95%, and the silane coupling agent used is γ-methoxypropyl silane.

5. The process for the efficient synthesis of PAO-X HVI composite base oil as claimed in claim 1, wherein: The shear rate of the high shear mixing in step S5 is > 10,000 s -1 The mixing temperature is controlled at 80 - 100 °C.

6. The process for the efficient synthesis of PAO-X HVI composite base oil as claimed in claim 1, wherein: In step S6, the defoaming is performed by standing under vacuum for 30 min, and the microfiltration uses 320 μm and 100 μm filters in sequence.

7. The process for the efficient synthesis of PAO-X HVI composite base oil as claimed in claim 1, wherein: In step S6, 0.05-0.2 wt% phenolic antioxidant, 0.01-0.05 wt% phosphate extreme pressure agent, and 0.1-0.3 wt% emulsifying dispersant are also added online to improve the antioxidant performance and low-temperature fluidity of the finished product.

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