Method and system for preparing high-viscosity poly alpha-olefin
By using a premixed-step activation process and adjusting the cycle ratio based on feedback signals from an online viscometer, the problems of catalyst residue and uneven molecular weight distribution in the preparation of high-viscosity polyα-olefins were solved, achieving efficient and stable product performance control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ENERGY GRP NINGXIA COAL IND CO LTD
- Filing Date
- 2026-02-12
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies for preparing high-viscosity poly-α-olefins suffer from problems such as high catalyst residue, excessively wide molecular weight distribution, and inconsistent performance, making it difficult to achieve precise control and efficient utilization of the catalyst.
A premixed-step activation process is adopted, in which a cationic active center is constructed by premixing a metallocene catalyst and an initiator with a co-catalyst. The cycle ratio is dynamically adjusted by combining the feedback signal from an online viscometer to achieve precise control of the degree of polymerization and avoid the generation of inactive species and the deactivation of active centers.
It significantly improves catalytic efficiency, keeps the product molecular weight distribution stable within an excellent range, ensures high consistency in product viscosity and pour point, and has low catalyst residue, making it suitable for large-scale industrial production.
Smart Images
Figure CN122011245A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyalphaolefin preparation technology, and specifically to a method and system for preparing high-viscosity polyalphaolefins. Background Technology
[0002] Polyalphaolefin (PAO) is a widely used synthetic lubricating oil base oil with good thermal stability, oxidation stability, and low-temperature performance. It is widely used in automotive engine oils, industrial lubricants, and other fields, and is currently the most widely used, most comprehensive in performance, and reasonably priced synthetic base oil. PAO synthetic oil products are currently classified into low-viscosity, medium-viscosity, and high-viscosity oils based on their viscosity.
[0003] mPAO (metallocene polyalphaolefin) refers to a high-performance synthetic lubricating oil base oil synthesized by the polymerization of alpha-olefins using metallocene catalysts. In the synthesis of polyalphaolefins (PAO), metallocene catalysts present significant technical challenges for industrial production due to their ultra-high catalytic activity (typically requiring only ppm-level dosage) and the high viscosity of the reaction system. The degree of polymerization (molecular chain length), as a core control parameter, directly determines key performance indicators such as viscosity, pour point, and molecular weight distribution of the product. Therefore, in continuous industrial production, achieving precise control of trace amounts of catalyst to fully utilize its catalytic activity, while accurately regulating the degree of polymerization, to prepare high-viscosity mPAO products with low catalyst residue, low ash content, high purity, and excellent high and low temperature performance, is a pressing technical challenge that needs to be overcome. Summary of the Invention
[0004] The purpose of this invention is to overcome the problems of excessively wide molecular weight distribution and high catalyst residue in existing technologies, and to provide a method and system for preparing a high-viscosity polyalphaolefin.
[0005] To achieve the above objectives, the present invention provides a method for preparing high-viscosity polyα-olefins, the method comprising the following steps: S1: The metallocene catalyst solution and the initiator are premixed in a premixing tank to obtain a premix; S2: The premix, co-catalyst, α-olefin and recycled material are subjected to a first polymerization reaction in a first polymerization reactor to obtain an intermediate product; S3: After the intermediate product passes through the circulation pump and the online viscometer in sequence, part of the intermediate product is recycled to the first polymerization reactor, and the other part of the intermediate product enters the second polymerization reactor to carry out the second polymerization reaction. The circulation ratio of intermediate products circulated to the first polymerization reactor is controlled based on the viscosity value obtained from the online viscometer.
[0006] Preferably, the premixing temperature is 0-25°C; and / or, The metallocene catalyst solution is delivered to the premixing tank via a metallocene catalyst feed pump; and / or The initiator is delivered to the premix tank via an initiator feed pump.
[0007] Preferably, the premix is injected into the first polymerization reactor through a loop nozzle; Preferably, the annular nozzle is located below the liquid level inside the first polymerization reactor.
[0008] Preferably, the co-catalyst solution is transported to the first polymerization reactor by a co-catalyst feed pump through a co-catalyst feed pipeline; Preferably, one end of the co-catalyst feed pipeline is connected to the co-catalyst feed pump, and the other end extends below the liquid surface of the first polymerization reactor.
[0009] Preferably, the α-olefin is transported to the first polymerization reactor via an olefin feed pipeline.
[0010] Preferably, along the olefin feed direction, an olefin flow meter and an olefin regulating valve are sequentially installed on the olefin feed pipeline to control the feed flow rates of the metallocene catalyst, co-catalyst, and initiator based on the signal fed back by the olefin flow meter.
[0011] Preferably, the cycle ratio is 50-80%; and / or, When the viscosity value obtained by the online viscometer is lower than the preset value, the circulation ratio is increased; when the viscosity value obtained by the online viscometer is higher than the preset value, the circulation ratio is decreased.
[0012] Preferably, the metallocene catalyst comprises at least one selected from zirconium compounds, hafnium compounds, and titanocene compounds; and / or, The cocatalyst comprises at least one selected from N,N-dimethylaniline tetra(pentafluorophenyl)borate, triphenylmethyltetra(pentafluorophenyl)borate, and triphenylboron; and / or, The initiator includes at least one of triethylaluminum, triisobutylaluminum, methylaluminoxane, and modified methylaluminoxane; and / or The α-olefins include C8-C14 α-olefins.
[0013] A second aspect of the present invention provides a system for preparing high-viscosity poly-α-olefins, the system comprising an olefin feed line, a co-catalyst feed pump, a metallocene catalyst feed pump, an initiator feed pump, a premix tank, a first polymerization reactor, a circulation pump, an intermediate material line, and a second polymerization reactor; The metallocene catalyst feed pump and the initiator feed pump are respectively connected to the premix tank; The olefin feed pipeline, the co-catalyst feed pump, and the premix tank are respectively connected to the first polymerization reactor; The outlet of the first polymerization reactor is connected to the inlet of the circulating pump, and the outlet of the circulating pump is connected to the inlet of the intermediate material pipeline. The outlet of the intermediate material pipeline is connected to the circulating material inlet of the first polymerization reactor and the inlet of the second polymerization reactor, respectively. An online viscometer is installed on the intermediate material pipeline.
[0014] Preferably, the system further includes an intermediate product flow meter and an intermediate product regulating valve disposed between the outlet of the intermediate material pipeline and the second polymerization reactor.
[0015] Compared with related technologies, the present invention has the following beneficial effects: This invention provides a method for preparing high-viscosity polyα-olefins. By first forming an alkylation intermediate with a metallocene catalyst and initiator, and then constructing a cationic active center with a co-catalyst, the generation of inactive species and premature deactivation of the active center are effectively avoided, significantly improving catalytic efficiency (>40000 gPAO / gCat). Simultaneously, it ensures uniform dispersion of the catalytic system, solving the problem of excessively wide molecular weight distribution caused by local overheating and uneven concentration. Furthermore, based on real-time feedback signals from an online viscometer, a dynamic adjustment mechanism for the cycle ratio is established, achieving precise control of the degree of polymerization. This allows the product's molecular weight distribution index (PDI) to be stably controlled within an excellent range of 1.9-2.2, ensuring high consistency in key performance indicators such as product viscosity and pour point. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of a system for preparing high-viscosity poly-α-olefins in some preferred embodiments of the present invention.
[0017] Explanation of reference numerals in the attached figures 1. Catalyst feed pump; 2. Metallocene catalyst feed pump; 3. Initiator feed pump; 4. Premix tank; 5. Loop nozzle; 6. First polymerization reactor; 7. Circulation pump; 8. Second polymerization reactor; 11. Olefin flow meter; 12. Olefin regulating valve; 13. Catalyst flow meter; 14. Metallocene catalyst flow meter; 15. Initiator flow meter; 16. Online viscometer; 17. Level gauge; 18. Intermediate product flow meter; 19. Intermediate product regulating valve. Detailed Implementation
[0018] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0019] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.
[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions provided in the various embodiments of this invention can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0022] This invention provides a method for preparing high-viscosity polyα-olefins, the method comprising the following steps: S1: The metallocene catalyst solution and the initiator are premixed in premix tank 4 to obtain a premixed material; S2: The premix, co-catalyst, α-olefin and recycled material are subjected to a first polymerization reaction in the first polymerization reactor 6 to obtain an intermediate product; S3: After the intermediate product passes through the circulation pump 7 and the online viscometer 16 in sequence, part of the intermediate product is recycled to the first polymerization reactor 6, and the other part of the intermediate product enters the second polymerization reactor 8 to carry out the second polymerization reaction. The circulation ratio of intermediate products circulated to the first polymerization reactor 6 is controlled based on the viscosity value obtained by the online viscometer 16.
[0023] In some preferred embodiments, the metallocene catalyst solution is delivered to the premixing tank 4 via a metallocene catalyst feed pump 2. The metallocene catalyst feed pump 2 may be a metering pump equipped with a variable frequency motor.
[0024] Understandably, metallocene catalysts are typically complexes formed from group IVB transition metals and cyclopentadienyl (Cp) or their derivatives. In some preferred embodiments, the metallocene catalyst comprises at least one of zirconium, hafnium, and titanocene compounds. The solvent for the metallocene catalyst solution can be at least one of toluene, p-xylene, and tetrahydrofuran, and the concentration is typically 0.5-2 mol / L.
[0025] More preferably, a metallocene catalyst flow meter 14 is provided between the metallocene catalyst feed pump 2 and the premix tank 4 to monitor the flow rate of the metallocene catalyst solution.
[0026] In some preferred embodiments, the initiator is delivered to the premixing tank 4 via an initiator feed pump 3. The initiator feed pump 3 may be a metering pump with a variable frequency motor.
[0027] In some specific embodiments, the initiator includes at least one of triethylaluminum, triisobutylaluminum, methylaluminoxane, and modified methylaluminoxane.
[0028] More preferably, an initiator flow meter 15 is provided between the initiator feed pump 3 and the premix tank 4 to monitor the flow rate of the initiator.
[0029] In some specific embodiments, the premixing tank 4 can be a small jacketed stirred tank.
[0030] In some preferred embodiments, the premixing temperature is 0-25°C. For example, it can be 0°C, 5°C, 10°C, 15°C, 20°C, or 25°C.
[0031] In some specific embodiments, the residence time of the metallocene catalyst solution and the initiator during premixing in the premixing tank 4 can be 3-10 minutes.
[0032] In some preferred embodiments, the premix is injected into the first polymerization reactor 6 through a ring nozzle 5.
[0033] In some preferred embodiments, the annular nozzle 5 is located below the liquid surface within the first polymerization reactor 6. Using the annular nozzle 5 to spray the premix from below the liquid surface promotes thorough mixing of the materials. Sufficient contact between different reactants is necessary to ensure the smooth progress and completeness of the reaction. Spraying the premix from below the liquid surface allows it to directly enter the reaction liquid. Utilizing the liquid flow and the impact force of the spray, the premix is rapidly dispersed throughout the reaction system, reducing aggregation and stratification of materials above the liquid surface, thereby significantly improving the mixing effect between reactants. Simultaneously, it improves reaction efficiency. Spraying the premix from below the liquid surface accelerates the mass transfer process between reactants, speeding up the diffusion rate of reactant molecules, thus increasing reaction efficiency, significantly shortening reaction time, and improving production efficiency.
[0034] Specifically, the nozzle angle can be set to an angle of 30° to 60° with the vertical direction. By setting the nozzle angle, it is beneficial to expand the material dispersion range and ensure that the material feed has a certain horizontal component, allowing the premix to diffuse to a wider area in the reaction liquid and increasing the contact area with the reaction liquid. At the same time, this inclined spray angle helps to form a specific flow pattern in the reaction liquid, promoting good liquid circulation. It can also prevent the material from directly impacting the reaction vessel wall, preventing local material accumulation and uneven reaction.
[0035] In this invention, the co-catalyst can be injected into the first polymerization reactor 6 in the form of a solution. Preferably, the co-catalyst solution is transported to the first polymerization reactor 6 by a co-catalyst feed pump 1 via a co-catalyst feed pipeline. The co-catalyst feed pump 1 can be a metering pump equipped with a variable frequency motor.
[0036] In some specific embodiments, the cocatalyst includes at least one of N,N-dimethylaniline tetra(pentafluorophenyl)borate, triphenylmethyltetra(pentafluorophenyl)borate, and triphenylboron.
[0037] More preferably, one end of the co-catalyst feed pipeline is connected to the co-catalyst feed pump 1, and the other end enters from the top of the first polymerization reactor 6 and extends below the liquid surface of the first polymerization reactor 6.
[0038] More preferably, the outlet of the co-catalyst feed pipe extending into the first polymerization reactor 6 is located 0.5-1m downstream of the annular nozzle 5, which allows the co-catalyst to be injected into the first polymerization reactor 6 below the premix, further realizing the gradient activation of the reactants.
[0039] In some specific embodiments, a catalyst feed meter 13 is provided on the catalyst feed pipeline to monitor the catalyst feed flow rate.
[0040] In some preferred embodiments, in step S2, the amount of α-olefin used is 20-80% by weight, and the amount of recycled material used is 20-80% by weight, based on the total weight of the α-olefin and the recycled material. As an example, the amount of α-olefin used can be 20%, 30%, 40%, 50%, 60%, 70%, or 80% by weight, and the amount of recycled material used can be 20%, 30%, 40%, 50%, 60%, 70%, or 80% by weight.
[0041] Understandably, in the method described in this invention, to address the problem of rapid thickening and decreased mass transfer efficiency in the reaction system caused by the ultra-high activity of metallocene catalysts, the inventors creatively adopted a premixed-stepwise activation process: the metallocene catalyst and initiator are premixed at 0~25℃ and then injected into the first reaction vessel through a loop nozzle 5; the co-catalyst solution is injected 0.5~1m below the loop nozzle 5. This design achieves gradient activation of the reactants, ensuring that the metallocene first forms an alkylation intermediate with the initiator, and then constructs a cationic active center with the organoboronide. This effectively avoids the formation of inactive species and premature deactivation of active centers, significantly improving catalytic efficiency (>40000gPAO / gCat), while ensuring uniform dispersion of the catalytic system and solving the problem of excessively wide molecular weight distribution caused by local overheating and uneven concentration.
[0042] In some preferred embodiments, the α-olefin is fed into the first polymerization reactor 6 via an olefin feed pipeline. The α-olefin can be an α-olefin pretreated by nitrogen bubbling + alkali metal impurity removal + molecular sieve adsorption, and is typically selected from C8 to C14 α-olefins. Specifically, the α-olefin can be a C8 to C14 α-olefin obtained from petroleum cracking, or a C8 to C12 α-olefin obtained from coal-based Fischer-Tropsch synthesis.
[0043] In some preferred embodiments, along the olefin feed direction, an olefin flow meter 11 and an olefin regulating valve 12 are sequentially provided on the olefin feed pipeline. The olefin flow meter 11 is used to monitor the flow rate of α-olefin, and the system regulating valve is used to regulate the feed flow rate of α-olefin.
[0044] In a preferred embodiment, the feed flow rates of the metallocene catalyst, co-catalyst, and initiator can be controlled based on the signal fed back from the olefin flow meter 11. By adjusting the precise ratio of the metallocene catalyst, co-catalyst, and initiator in real time through the α-olefin flow rate, the catalyst utilization rate can be significantly improved, resulting in extremely low catalyst residue in the product (ash content < 50 ppm) and a purity level that is among the industry's leading levels.
[0045] In some preferred embodiments, the first polymerization reactor 6 may be a jacketed stirred tank.
[0046] In a preferred embodiment, the first polymerization reactor 6 is connected to a level gauge 17 for monitoring the liquid level inside the reactor 6. The signal fed back by the level gauge 17 can be transmitted to the olefin flow meter 11 and the olefin regulating valve 12, and then the α-olefin flow rate can be adjusted by the olefin regulating valve 12 to maintain a stable liquid level inside the first polymerization reactor 6.
[0047] In a preferred embodiment, in step S2, the conditions for the first polymerization reaction include: a reaction temperature of 60~150°C, and the reaction being carried out in the presence of a protective gas.
[0048] In this invention, the protective gas can be provided by nitrogen or an inert gas.
[0049] In some specific embodiments, the residence time of the material in the first polymerization reactor 6 is 30-150 minutes. The residence time can be controlled based on the liquid volume in the first reactor (which can be obtained by combining the data from the level gauge 17) and the feed flow rate.
[0050] In a preferred embodiment, in step S2, the recycled material is the material discharged from the outlet of the first polymerization reactor 6, and then returned to the first polymerization reactor 6 after passing through the circulation pump 7 and the online viscometer 16.
[0051] In some preferred embodiments, in step S3, the intermediate product is drawn from the bottom of the first polymerization reactor 6, and then passes sequentially through the circulation pump 7 and the online viscometer 16. A portion is recycled back to the first polymerization reactor 6, while the other portion is transported to the second polymerization reactor 8 for the second polymerization reaction. Specifically, the circulation pump 7 can be a gear pump, and the second polymerization reactor 8 can be a jacketed stirred tank.
[0052] In some preferred embodiments, the recycling ratio is 50-80%. The recycling ratio refers to the mass percentage of material recycled back to the first polymerization reactor 6.
[0053] In some preferred embodiments, the specific method for adjusting the cycle ratio based on the signal fed back by the online viscometer 16 can be as follows: when the viscosity value obtained by the online viscometer 16 is lower than a preset value, the cycle ratio is increased; when the viscosity value obtained by the online viscometer 16 is higher than the preset value, the cycle ratio is decreased. The preset value can be set as needed.
[0054] In some preferred embodiments, the conditions for the second polymerization reaction include: a reaction temperature of 80~200°C, and the reaction being carried out in the presence of a protective gas.
[0055] In some preferred embodiments, the method further includes: refining the crude poly-α-olefin product obtained from the second polymerization reaction.
[0056] The polyalphaolefin products prepared by the method described in this invention have both excellent viscosity-temperature properties and low-temperature fluidity. The viscosity index of PAO100 product is >200 and the pour point is <-40℃, which fully meets the application requirements of high-end lubricants.
[0057] A second aspect of the present invention provides a system for preparing high-viscosity polyα-olefins, in conjunction with reference to [the relevant literature]. Figure 1 The system includes an olefin feed pipeline, a co-catalyst feed pump 1, a metallocene catalyst feed pump 2, an initiator feed pump 3, a premix tank 4, a first polymerization reactor 6, a circulation pump 7, an intermediate material pipeline, and a second polymerization reactor 8. The metallocene catalyst feed pump 2 and the initiator feed pump 3 are respectively connected to the premix tank 4; The olefin feed pipeline, the co-catalyst feed pump 1, and the premix tank 4 are respectively connected to the first polymerization reactor 6; The outlet of the first polymerization reactor 6 is connected to the inlet of the circulating pump 7, and the outlet of the circulating pump 7 is connected to the inlet of the intermediate material pipeline. The outlet of the intermediate material pipeline is connected to the circulating material inlet of the first polymerization reactor 6 and the inlet of the second polymerization reactor 8, respectively. An online viscometer 16 is installed on the intermediate material pipeline.
[0058] In some preferred embodiments, along the α-olefin feed flow direction, an olefin flow meter 11 and an olefin regulating valve 12 are sequentially provided on the olefin feed pipeline. By setting the olefin flow meter 11 and the olefin regulating valve 12, the α-olefin feed rate can be monitored and controlled.
[0059] In some specific embodiments, the outlet of the olefin feed line is connected to the olefin inlet of the first polymerization reactor 6, which is located at the top of the first polymerization reactor 6.
[0060] In some preferred embodiments, the co-catalyst feed pump 1 is connected to the first polymerization reactor 6 via a co-catalyst feed pipeline. A co-catalyst flow meter 13 is provided on the co-catalyst feed pipeline to monitor the flow rate of the co-catalyst.
[0061] More preferably, one end of the co-catalyst feed pipe is connected to the co-catalyst feed pump 1, and the other end passes through the top of the first polymerization reactor 6 and extends into the first polymerization reactor 6, so that the outlet of the co-catalyst feed pipe is located inside the first polymerization reactor 6.
[0062] In some preferred embodiments, a metallocene catalyst flow meter 14 is provided on the connecting pipeline between the metallocene catalyst feed pump 2 and the premix tank 4, and the metallocene catalyst can be used to monitor the flow rate of the metallocene solution.
[0063] In some preferred embodiments, an initiator flow meter 15 is provided on the connecting pipeline between the initiator feed pump 3 and the premix tank 4, and the initiator flow meter 15 can monitor the flow rate of the initiator.
[0064] In some preferred embodiments, the premixing tank 4 may be a jacketed small stirred tank, which is used for premixing metallocene catalysts and initiators.
[0065] In some preferred embodiments, the premix tank 4 is connected to the first polymerization reactor 6 via a premix feed pipe. One end of the premix feed pipe is connected to the outlet of the premix tank 4, and the other end passes through the top of the first polymerization reactor 6 and extends into the first polymerization reactor 6, and is connected to a ring nozzle 5, so that the premix is sprayed into the first polymerization reactor 6 through the ring nozzle 5.
[0066] In some specific embodiments, the annular nozzle 5 is located above the outlet of the catalyst feed line.
[0067] In some preferred embodiments, the system further includes a level gauge 17 for monitoring the liquid level inside the first stirred reactor. Information from the signal fed back by the level gauge 17 can be transmitted to the olefin flow meter 11 and the olefin regulating valve 12, and then the α-olefin flow rate can be adjusted via the olefin regulating valve 12 to maintain a stable liquid level within the first polymerization reactor 6.
[0068] In some specific embodiments, the outlet of the first polymerization reactor 6 is located at the bottom of the first polymerization reactor 6.
[0069] In some preferred embodiments, a portion of the intermediate product flowing through the online viscometer 16 is returned to the first polymerization reactor 6 via the recycling inlet to undergo polymerization with fresh α-olefins, while the other portion enters the second polymerization reactor 8 via the inlet to undergo a second polymerization reaction. The online viscometer 16 is used to monitor the real-time viscosity of the intermediate product from the first polymerization reactor 6, and the proportion of intermediate product recycled back to the first polymerization reactor 6 can be adjusted based on the signal fed back from the online viscometer 16.
[0070] In some specific embodiments, along the material flow direction, an intermediate product flow meter 18 and an intermediate product regulating valve 19 are sequentially installed between the outlet of the intermediate material pipeline and the second polymerization reactor 8. The intermediate product flow meter 18 and the intermediate product regulating valve 19 can be used to monitor and regulate the amount of intermediate product entering the second polymerization reactor 8. Specifically, the opening of the intermediate product regulating valve 19 can be controlled by the online viscosity value fed back by the online viscometer 16, thereby controlling the amount of intermediate product entering the second polymerization reactor 8, that is, controlling the proportion of intermediate product recycled back to the first polymerization reactor 6.
[0071] In some specific embodiments, the system further includes a control unit (in Figure 1 (Not shown in the image) The control unit can receive the signal fed back by the online viscometer 16, process the feedback signal, and then issue a command to control the intermediate product regulating valve 19, thereby controlling the circulation ratio of the intermediate product; the control unit can also receive the signal fed back by the level gauge 17, process the feedback signal, and then issue a command to control the olefin regulating valve 12, thereby controlling the feed flow rate of α-olefin.
[0072] In some specific embodiments, the second polymerization reactor 8 can be a jacketed stirred tank. The bottom of the second polymerization reactor 8 is provided with a crude product outlet, through which the crude poly-α-olefin obtained by the second polymerization reaction is discharged.
[0073] In some specific embodiments, the system further includes a refining unit (in Figure 1 (Not shown in the image), the refining unit is used to refine the crude poly-α-olefin from the second polymerization reactor 8.
[0074] The system for preparing high-viscosity polyα-olefins provided by this invention utilizes a premixing tank 4 connected to the metallocene catalyst feed pump 2 and the initiator feed pump 3. This allows the metallocene catalyst and initiator to be premixed before being injected into the first polymerization reactor 6, avoiding the generation of inactive species and significantly improving catalytic efficiency. An online viscometer 16 monitors the viscosity of the intermediate product discharged from the first polymerization reactor 6 in real time. Based on the real-time feedback signal from the online viscometer 16, the circulation ratio is dynamically adjusted to achieve precise control of the degree of polymerization, ensuring highly stable product performance (viscosity, pour point). Through the coordinated feeding of α-olefin olefins, metallocene catalyst, co-catalyst, and initiator, precise control of the catalyst at the ppm level is achieved, significantly improving utilization and reducing residue (ash content < 50 ppm). The system design is suitable for continuous production, with stable processes, good product consistency, and is suitable for large-scale applications.
[0075] To make the objectives and advantages of the present invention clearer, the method and system for preparing high-viscosity polyα-olefins and their effects are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and should not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventionally selected in the art. Experimental methods in the embodiments that do not specify specific conditions were implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.
[0076] In the following embodiments, in conjunction with reference to Figure 1 The systems used for preparing high-viscosity polyα-olefins include: The system includes an olefin feed line, a co-catalyst feed pump 1, a metallocene catalyst feed pump 2, an initiator feed pump 3, a premix tank 4, a first polymerization reactor 6, a level gauge 17, a circulation pump 7, an intermediate material line, a second polymerization reactor 8, a control unit, and a refining unit. The outlet of the olefin feed pipeline is connected to the olefin inlet of the first polymerization reactor 6, and the olefin inlet is located at the top of the first polymerization reactor 6; along the α-olefin feed flow direction, an olefin flow meter 11 and an olefin regulating valve 12 are sequentially provided on the olefin feed pipeline. The co-catalyst feed pump 1 is connected to the first polymerization reactor 6 through the co-catalyst feed pipeline. The co-catalyst feed pipeline is equipped with a co-catalyst flow meter 13. One end of the co-catalyst feed pipeline is connected to the co-catalyst feed pump 1, and the other end passes through the top of the first polymerization reactor 6 and extends into the first polymerization reactor 6. The outlet of the co-catalyst feed pipeline is located inside the first polymerization reactor 6. The metallocene catalyst feed pump 2 is connected to the premix tank 4, and a metallocene catalyst flow meter 14 is provided on the connecting pipeline between the metallocene catalyst feed pump 2 and the premix tank 4; the initiator feed pump 3 is connected to the premix tank 4, and an initiator flow meter 15 is provided on the connecting pipeline between the initiator feed pump 3 and the premix tank 4; the premix tank 4 is connected to the first polymerization reactor 6 through a premix feed pipe, one end of the premix feed pipe is connected to the outlet of the premix tank 4, and the other end passes through the top of the first polymerization reactor 6 and extends into the first polymerization reactor 6, and has a ring nozzle 5, which is located above the outlet of the co-catalyst feed pipe; The level gauge 17 is connected to the first polymerization reactor 6 and is used to monitor the liquid level inside the first polymerization reactor 6. The outlet of the first polymerization reactor 6 is connected to the inlet of the circulating pump 7, and the outlet of the circulating pump 7 is connected to the inlet of the intermediate material pipeline. The outlet of the intermediate material pipeline is connected to the circulating material inlet of the first polymerization reactor 6 and the inlet of the second polymerization reactor 8, respectively; and the online viscometer 16 is installed on the intermediate material pipeline. An intermediate product flow meter 18 and an intermediate product regulating valve 19 are sequentially installed between the outlet of the intermediate material pipeline and the second polymerization reactor 8. The bottom of the second polymerization reactor 8 is provided with a crude product outlet; the refining unit is connected to the crude product outlet; The control unit is used to receive signals from the level gauge 17 and the online viscometer 16, and can issue commands to the olefin regulating valve 12 and the intermediate product regulating valve 19.
[0077] Example 1 S1: The metallocene catalyst (zirconia compound) solution (concentration of 1 mol / L) enters the premixing tank 4 through the metallocene catalyst feed pump 2, and the initiator (triisobutylaluminum) enters the premixing tank 4 through the initiator feed pump 3. The metallocene catalyst solution and the initiator (triisobutylaluminum) are premixed in the premixing tank 4 to obtain a premixed material; the premixing temperature is 15℃. S2: α-Olefins (coal-based Fischer-Tropsch C10) are fed into the first polymerization reactor 6 via the olefin feed pipeline. The premix is injected into the first polymerization reactor 6 through the ring nozzle 5 of the premix feed pipeline, and is sprayed out below the liquid surface within the first polymerization reactor 6. The co-catalyst (triphenylmethyltetra(pentafluorophenyl)borate) is injected into the first polymerization reactor 6 below the premix (0.8m). The premix, co-catalyst, α-olefin, and recycled material undergo a first polymerization reaction in the first polymerization reactor 6 to obtain an intermediate product. The temperature of the first polymerization reaction is 80°C, the residence time is 40 minutes, and the reaction pressure is 0.1-0.2 MPa. Based on the total weight of the α-olefin and recycled material, the amount of α-olefin is 30% by weight, and the amount of recycled material is 70% by weight. S3: The intermediate product is discharged from the outlet of the first polymerization reactor 6, and then passes through the circulation pump 7 and the intermediate material pipeline in sequence. Part of the intermediate product is recycled back to the first polymerization reactor 6, while the other part enters the second polymerization reactor 8 for the second polymerization reaction. The temperature of the second polymerization reaction is 140℃, the residence time is 50 minutes, and the reaction pressure is 0.1-0.2 MPa. The recycling ratio of the intermediate product recycled back to the first polymerization reactor 6 is controlled according to the viscosity value obtained by the online viscometer 16. When the viscosity value obtained by the online viscometer 16 is lower than the preset value (100 mm), the recycling ratio is controlled. 2When the viscosity value obtained by the online viscometer 16 is higher than the preset value, the circulation ratio is increased; when the viscosity value is higher than the preset value, the circulation ratio is decreased. S4: The crude product obtained from the second polymerization reactor 8, after subsequent refining, yielded a product with a kinematic viscosity (100℃) of 102 mm. 2 / s, viscosity index 200~210, molecular weight distribution PDI 2.1.
[0078] Example 2 S1: The metallocene catalyst (zirconia compound) solution (concentration of 1 mol / L) enters the premixing tank 4 through the metallocene catalyst feed pump 2, and the initiator (triisobutylaluminum) enters the premixing tank 4 through the initiator feed pump 3. The metallocene catalyst solution and the initiator (triisobutylaluminum) are premixed in the premixing tank 4 to obtain a premixed material; the premixing temperature is 15℃. S2: α-olefins (coal-based Fischer-Tropsch C8+C10) are fed into the first polymerization reactor 6 via an olefin feed pipeline. A premix is injected into the first polymerization reactor 6 through a ring nozzle 5 in the premix feed pipeline, and the premix is sprayed out below the liquid surface in the first polymerization reactor 6. A co-catalyst is injected into the first polymerization reactor 6 below the premix (0.5m). The premix, co-catalyst (triphenylmethyltetra(pentafluorophenyl)borate), α-olefin, and recycled material are subjected to a first polymerization reaction in the first polymerization reactor 6 to obtain an intermediate product. The reaction temperature is 70°C, the residence time is 60 minutes, and the reaction pressure is 0.1-0.2 MPa. Based on the total weight of the α-olefin and recycled material, the amount of α-olefin is 20% by weight, and the amount of recycled material is 80% by weight. S3: The intermediate product is discharged from the outlet of the first polymerization reactor 6, and then passes through the circulation pump 7 and the intermediate material pipeline in sequence. Part of the intermediate product is recycled back to the first polymerization reactor 6, while the other part enters the second polymerization reactor 8 for the second polymerization reaction. The temperature of the second polymerization reaction is 120℃, the residence time is 60 minutes, and the reaction pressure is 0.1-0.2 MPa. The recycling ratio of the intermediate product recycled back to the first polymerization reactor 6 is controlled according to the viscosity value obtained by the online viscometer 16. When the viscosity value obtained by the online viscometer 16 is lower than the preset value (100 mm), the recycling ratio is controlled. 2 When the viscosity value obtained by the online viscometer 16 is higher than the preset value, the circulation ratio is increased; when the viscosity value is higher than the preset value, the circulation ratio is decreased. S4: The crude product obtained from the second polymerization reactor 8, after subsequent refining, yielded a product with a kinematic viscosity (100℃) of 103.2 mm. 2 / s, viscosity index 200~210, molecular weight distribution PDI 1.97.
[0079] Example 3 S1: The metallocene catalyst (zirconia compound) solution (concentration of 1 mol / L) enters the premixing tank 4 through the metallocene catalyst feed pump 2, and the initiator (triisobutylaluminum) enters the premixing tank 4 through the initiator feed pump 3. The metallocene catalyst solution and the initiator (triisobutylaluminum) are premixed in the premixing tank 4 to obtain a premixed material; the premixing temperature is 15℃. S2: α-olefin (coal-based Fischer-Tropsch C10) is fed into the first polymerization reactor 6 via the olefin feed pipeline. The premix is injected into the first polymerization reactor 6 through the ring nozzle 5 of the premix feed pipeline, and the premix is sprayed out below the liquid surface in the first polymerization reactor 6. The co-catalyst is injected into the first polymerization reactor 6 below the premix (1m). The premix, co-catalyst (N,N-dimethylaniline tetra(pentafluorobenzene)borate), α-olefin, and recycled material are subjected to a first polymerization reaction in the first polymerization reactor 6 to obtain an intermediate product. The temperature of the first polymerization reaction is 100℃, the residence time is 60 minutes, and the reaction pressure is 0.1-0.2 MPa. Based on the total weight of the α-olefin and recycled material, the amount of α-olefin is 40% by weight, and the amount of recycled material is 60% by weight. S3: The intermediate product is discharged from the outlet of the first polymerization reactor 6, and then passes through the circulation pump 7 and the intermediate material pipeline in sequence. Part of the intermediate product is recycled back to the first polymerization reactor 6, while the other part enters the second polymerization reactor 8 for the second polymerization reaction. The temperature of the second polymerization reaction is 120℃, the residence time is 60 minutes, and the reaction pressure is 0.1-0.2 MPa. The recycling ratio of the intermediate product recycled back to the first polymerization reactor 6 is controlled according to the viscosity value obtained by the online viscometer 16. When the viscosity value obtained by the online viscometer 16 is lower than the preset value (100 mm), the recycling ratio is controlled. 2 When the viscosity value obtained by the online viscometer 16 is higher than the preset value, the circulation ratio is increased; when the viscosity value is higher than the preset value, the circulation ratio is decreased. S4: The crude product obtained from the second polymerization reactor 8 undergoes subsequent refining treatment, resulting in a kinematic viscosity (100℃) of 98 mm. 2 / s, viscosity index 200~210, molecular weight distribution PDI 2.03.
[0080] Comparative Example 1 Poly-α-olefins were prepared using an alternative system, which differed from the system used in the examples only in that it did not have an online viscometer 16.
[0081] The preparation process is basically the same as in Example 1, except that the opening of the intermediate product regulating valve 19 is kept constant, so that the circulation ratio of the intermediate product is always maintained at 10%.
[0082] The crude product obtained from the second polymerization reactor 8 was further refined, and the kinematic viscosity (100℃) of the resulting product reached 117 mm. 2 / s, viscosity index 217, molecular weight distribution PDI 2.67.
[0083] It should be understood that any parts not described in detail in this specification belong to the prior art.
[0084] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing high-viscosity polyα-olefins, characterized in that, The method includes the following steps: S1: The metallocene catalyst solution and the initiator are premixed in a premix tank (4) to obtain a premixed material; S2: The premix, co-catalyst, α-olefin and recycled material are subjected to a first polymerization reaction in the first polymerization reactor (6) to obtain an intermediate product; S3: After the intermediate product passes through the circulation pump (7) and the online viscometer (16) in sequence, part of the intermediate product is recycled to the first polymerization reactor (6), and the other part of the intermediate product enters the second polymerization reactor (8) to carry out the second polymerization reaction; The circulation ratio of intermediate products circulated to the first polymerization reactor (6) is controlled based on the viscosity value obtained by the online viscometer (16).
2. The method according to claim 1, characterized in that, The temperature of the premix is 0-25℃; and / or, The metallocene catalyst solution is delivered to the premixing tank (4) via a metallocene catalyst feed pump (2); and / or, The initiator is delivered to the premix tank (4) via the initiator feed pump (3).
3. The method according to claim 1 or 2, characterized in that, The premix is injected into the first polymerization reactor (6) through a ring nozzle (5); Preferably, the annular nozzle (5) is located below the liquid level inside the first polymerization reactor (6).
4. The method according to claim 1 or 2, characterized in that, The co-catalyst solution is transported to the first polymerization reactor (6) by the co-catalyst feed pump (1) through the co-catalyst feed pipeline; Preferably, one end of the co-catalyst feed pipeline is connected to the co-catalyst feed pump (1), and the other end extends below the liquid surface of the first polymerization reactor (6).
5. The method according to claim 1 or 2, characterized in that, The α-olefin is transported to the first polymerization reactor (6) via an olefin feed pipeline.
6. The method according to claim 5, characterized in that, Along the olefin feed direction, an olefin flow meter (11) and an olefin regulating valve (12) are sequentially installed on the olefin feed pipeline. The feed flow rates of the metallocene catalyst, co-catalyst and initiator are controlled according to the signal fed back by the olefin flow meter (11).
7. The method according to claim 1 or 2, characterized in that, The cycle ratio is 50-80%; and / or, When the viscosity value obtained by the online viscometer (16) is lower than the preset value, the cycle ratio is increased; when the viscosity value obtained by the online viscometer (16) is higher than the preset value, the cycle ratio is decreased.
8. The method according to claim 1 or 2, characterized in that, The metallocene catalyst comprises at least one of zirconium compounds, hafnium compounds, and titanocene compounds; and / or, The cocatalyst comprises at least one selected from N,N-dimethylaniline tetra(pentafluorophenyl)borate, triphenylmethyltetra(pentafluorophenyl)borate, and triphenylboron; and / or, The initiator includes at least one selected from triethylaluminum, triisobutylaluminum, methylaluminoxane, and modified methylaluminoxane; and / or, The α-olefins include C8-C14 α-olefins.
9. A system for preparing high-viscosity polyα-olefins, characterized in that, The system includes an olefin feed line, a co-catalyst feed pump (1), a metallocene catalyst feed pump (2), an initiator feed pump (3), a premix tank (4), a first polymerization reactor (6), a circulation pump (7), an intermediate material line, and a second polymerization reactor (8). The metallocene catalyst feed pump (2) and the initiator feed pump (3) are respectively connected to the premix tank (4); The olefin feed pipeline, the co-catalyst feed pump (1) and the premix tank (4) are respectively connected to the first polymerization reactor (6); The outlet of the first polymerization reactor (6) is connected to the inlet of the circulating pump (7), and the outlet of the circulating pump (7) is connected to the inlet of the intermediate material pipeline; The outlet of the intermediate material pipeline is connected to the circulating material inlet of the first polymerization reactor (6) and the inlet of the second polymerization reactor (8), respectively. An online viscometer (16) is installed on the intermediate material pipeline.
10. The system according to claim 9, characterized in that, The system also includes an intermediate product flow meter (18) and an intermediate product regulating valve (19) located between the outlet of the intermediate material pipeline and the second polymerization reactor (8).