Method and system for preparing mPAO

Abstract

The invention relates to a PAO synthesis technology in the field of petrochemical engineering, and discloses a method and a system for preparing mPAO. The method comprises the following steps: 1) cooling at least part of a refined alpha-olefin raw material, respectively mixing the cooled alpha-olefin raw material with a main catalyst and a cocatalyst to obtain a main catalyst solution and a cocatalyst solution, heating the rest of the alpha-olefin raw material, and mixing the heated alpha-olefin raw material with an impurity removal catalyst, the main catalyst solution and the cocatalyst solution to obtain a premix; (2) sequentially carrying out first polymerization reaction on the premix in the step (1) in a pipeline reactor and carrying out second polymerization reaction in a reaction kettle; wherein the reaction time of the first polymerization reaction is 1 to 120 minutes; the reaction time of the second polymerization reaction is 1 to 180 minutes; and 3) sequentially carrying out quenching, adsorption filtration, separation purification and hydrogenation reaction on the reaction product obtained in the step 2). The method can effectively improve the quality of the mPAO product, and has the advantages of large treatment scale, high olefin conversion rate and less system waste discharge.

Description

Technical Field

[0001] This invention relates to PAO synthesis technology in the petrochemical field, specifically to a method and system for preparing mPAO. Background Technology

[0002] Polyalphaolefin (PAO) synthetic oil is a polymer obtained by linear alpha-olefin polymerization. It is the most important Group IV synthetic lubricant base oil. It has the characteristics of high viscosity index, low pour point, high flash point, good thermal oxidation stability, excellent high and low temperature performance, and long service life. It can reduce equipment corrosion and wear, reduce equipment maintenance cycle, and improve equipment utilization and service life. It is particularly suitable for aerospace, military and other fields.

[0003] Polyalphaolefins (PAOs) are typically produced through olefin-catalyzed polymerization, using monomers or mixed olefins from C6-C14 PAOs as feedstocks. The polymerization catalysts mainly include Ziegler-Natta catalysts, Lewis acid catalysts, ionic liquid catalysts, and metallocene catalysts. PAO molecules synthesized using metallocene catalysts have side chains of varying lengths in their main chain, exhibiting a comb-like structure without upright side chains. Compared to conventional PAOs, this shape effectively improves rheological properties and flow characteristics, resulting in products with better shear stability, lower pour points, and higher viscosity indexes. This type of PAO synthesized using metallocene catalysts is called metallocene polyalphaolefin (mPAO).

[0004] In existing mPAO preparation technologies, inert components such as toluene are required during catalyst dissolution, leaving solvent residues in the reaction products that cannot be completely separated. This places high demands on subsequent separation systems, is complex to operate, and significantly impacts product quality and cost. Furthermore, existing processes often employ stirred tank reactors, which cannot effectively remove the concentrated heat released during mPAO synthesis, and this continuous reaction method makes it impossible to precisely control the degree of polymerization of the reaction products. Achieving large-scale production through multiple reactors in series results in high equipment investment, long processes, long residence times, low efficiency in intermittent production, and low olefin conversion rates. Patent application CN112029021A discloses a continuous polymerization method that uses circulating water coils for cooling within the polymerization reaction unit to achieve continuous mPAO production. However, this method cannot effectively remove reaction heat in the initial stages of the reaction, leading to excessively high local temperatures in the reaction system and greater differences in the degree of polymerization of the products. Patent application CN105062555A discloses a method for preparing mPAO using coal-based α-olefins as raw materials. The method involves dehydrating and deoxidizing the raw materials with alkali metals, followed by reaction, quenching, and distillation to obtain mPAO. However, this method requires stringent raw material purification and reaction conditions, making it impractical for industrial production. Patent application CN112159489A discloses an mPAO preparation method using a multi-stage series-parallel connected polymerization reactor to achieve large-scale synthesis. However, the series reactor cannot effectively remove heat, resulting in product quality fluctuations and excessive metal elements. Patent application CN110624487A discloses a reaction device with a cooling system including a jacket, built-in coils, an external circulation pump, an external circulation cooler, and a refrigerator. This method achieves PAO synthesis through stirring and shearing combined with external circulation cooling. However, this method suffers from untimely heat removal, and the product cannot be fully mixed uniformly during the external circulation heat removal process, leading to uneven molecular polymerization. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of unstable product quality caused by the inability to simultaneously achieve mass transfer and heat transfer in existing mPAO polymerization processes. This invention provides a method and system for preparing mPAO, which has stable temperature control, can effectively improve the quality of mPAO products, and has a large processing scale, high olefin conversion rate, and low system waste discharge.

[0006] To achieve the above objectives, the present invention provides a method for preparing mPAO, the method comprising: 1) At least a portion of the refined α-olefin feedstock is cooled and then mixed with the main catalyst and the co-catalyst to obtain a main catalyst solution and a co-catalyst solution. The remaining portion is heated and then mixed with the impurity removal catalyst, the main catalyst solution and the co-catalyst solution to obtain a premix. 2) The premix from step 1) undergoes a first polymerization reaction in a pipeline reactor and a second polymerization reaction in a reaction vessel; wherein the reaction time of the first polymerization reaction is 1~120 min; and the reaction time of the second polymerization reaction is 1~180 min. 3) The reaction products obtained in step 2) are sequentially subjected to quenching, adsorption filtration, separation and purification and hydrogenation reaction.

[0007] Preferably, at least a portion of the α-olefin feedstock is cooled to 5-45°C and then mixed with the main catalyst and the co-catalyst, respectively.

[0008] Preferably, the concentration of the main catalyst in the main catalyst solution is 1~8 wt‰.

[0009] Preferably, the concentration of the co-catalyst in the co-catalyst solution is 2~16 wt‰.

[0010] Preferably, the remaining portion of the α-olefin feedstock is heated to 80-130°C and then mixed with the impurity removal catalyst, the main catalyst solution, and the co-catalyst solution.

[0011] Preferably, the main catalyst is a metallocene catalyst.

[0012] Preferably, the co-catalyst is an organoboronide.

[0013] Preferably, the impurity removal catalyst is at least one selected from aluminum oxane, alkyl aluminum compound, and alkyl aluminum chloride.

[0014] Preferably, the quenching agent used in the quenching is at least one selected from methanol, ethanol, ethanol hydrochloride, and isopropanol.

[0015] Preferably, the adsorbent used in the adsorption filtration is at least one of diatomaceous earth, silica gel, kaolin, and molecular sieve.

[0016] Preferably, the mixing time of the premix is ​​1~180s, more preferably 1~60s.

[0017] Preferably, the conditions for the first polymerization reaction include: a temperature of 80~130℃, a pressure of 0.1~2MPa, and a reaction time of 1~20min.

[0018] Preferably, the conditions for the second polymerization reaction include: a temperature of 80~130℃, a pressure of 0.1~2MPa, and a reaction time of 40~80min.

[0019] Preferably, the separation and purification includes: sending the material obtained after adsorption filtration to a primary distillation column, sending the separated gas phase to a primary gas-liquid separator, sending the liquid phase to a secondary distillation column, and recovering the liquid phase separated in the primary gas-liquid separator as a quenching agent; sending the gas phase separated in the secondary distillation column to a secondary gas-liquid separator, and collecting the liquid phase as a hydrogenation reaction feedstock, and collecting the liquid phase separated in the secondary gas-liquid separator as an α-olefin feedstock.

[0020] Preferably, the conditions for the hydrogenation reaction include: a pressure of 5-10 MPa, a temperature of 220-260°C, a hydrogen-to-oil ratio of 300-600:1, and a Ni-based catalyst and / or a Co-based catalyst.

[0021] Another aspect of the present invention provides a system for preparing mPAO, the system being used to implement the method according to any one of claims 1-8, the system comprising: A refining unit for refining α-olefin feedstock, wherein the refining unit is equipped with an α-olefin feedstock feed line; The premixing unit includes a cooler, a preheater, a main catalyst preparation tank, a co-catalyst preparation tank, and a premixing kettle; the main catalyst preparation tank is equipped with a main catalyst feed line, the co-catalyst preparation tank is equipped with a co-catalyst feed line, and the premixing kettle is equipped with a purification catalyst feed line; the refining unit is connected to the cooler and the preheater respectively, the cooler is connected to the main catalyst preparation tank and the co-catalyst preparation tank respectively, and the main catalyst preparation tank, the co-catalyst preparation tank, and the preheater are all connected to the premixing kettle; The polymerization reaction unit includes a pipeline reactor, a reaction vessel, and a quenching reaction vessel, wherein the premixing vessel, the pipeline reactor, the reaction vessel, and the quenching reaction vessel are connected in sequence. An adsorption filtration unit includes an adsorption filter; the adsorption filter is connected to the quenching reactor. The separation and purification unit includes a primary distillation column, a secondary distillation column, a primary gas-liquid separator, and a secondary gas-liquid separator; the adsorption filter is sequentially connected to the primary distillation column and the secondary distillation column, the primary gas-liquid separator is connected to the primary distillation column, and the secondary gas-liquid separator is connected to the secondary distillation column; The hydrogenation unit includes a hydrogenation reactor; the hydrogenation reactor is connected to the secondary distillation column.

[0022] Preferably, the pipeline reactor is equipped with a static mixer, which is at least one of the following: SK type mixer, SX type mixer, SL type mixer, and SH type mixer.

[0023] Preferably, the pipeline reactor is provided with a cooling jacket.

[0024] Preferably, the reactor is equipped with a coil inside and a jacket outside.

[0025] Preferably, the hydrogenation unit further includes a three-stage distillation column and a three-stage gas-liquid separator, wherein the three-stage distillation column is connected to the hydrogenation reactor and the three-stage gas-liquid separator, respectively.

[0026] Compared with the prior art, the present invention has the following advantages: 1) In this invention, the cooled α-olefin raw material is used as the catalyst to prepare the solvent, which reduces impurities in the reaction system, reduces the load on subsequent product separation and purification, and improves product quality.

[0027] 2) This invention adopts a segmented reaction form of premixing-pipeline mixing reaction-deep reaction, which effectively removes heat from the reaction and effectively solves the problems of concentrated heat release in the system at the beginning of the reaction and increased system viscosity as the reaction depth progresses during the mPAO synthesis process, which leads to a wide distribution of product polymerization degree and reduced quality due to untimely heat removal.

[0028] 3) The reaction system of this invention is simple, has a large processing scale, high olefin conversion rate, and low waste discharge, making it suitable for industrialization. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system for preparing mPAO in Example 1 of the present invention.

[0030] Explanation of reference numerals in the attached figures 101. Refining reactor; 102. Refining buffer tank; 3. Catalyst preparation tank; 4. Main catalyst preparation tank; 201. Cooler; 202. Preheater; 5. Premixing vessel; 6. Pipeline reactor; 7. Reactor; 801. Quenching reactor; 802. Quenching discharge pump; 9. Adsorption filter; 1001. Primary distillation column; 1002. Primary gas-liquid separator; 1101. Secondary distillation column; 1102. Secondary gas-liquid separator; 12. Buffer tank; 13. Hydrogenation refining pump; 14. Hydrogenation reactor; 1501. Tertiary distillation column; 1103. Tertiary gas-liquid separator; 16. Product tank.

[0031] A. α-olefin feedstock; B. co-catalyst; C. quencher; M. main catalyst; S. impurity removal catalyst. Detailed Implementation

[0032] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0033] 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.

[0034] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of technical features indicated. Therefore, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0035] In addition, terms such as “center,” “horizontal,” “up,” “down,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” that indicate orientation or positional relationship are based on the orientation or relative positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0036] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] In this invention, the method for preparing mPAO includes: 1) At least a portion of the refined α-olefin feedstock is cooled and then mixed with the main catalyst and the co-catalyst to obtain a main catalyst solution and a co-catalyst solution. The remaining portion is heated and then mixed with the impurity removal catalyst, the main catalyst solution and the co-catalyst solution to obtain a premix. 2) The premix from step 1) undergoes a first polymerization reaction in pipeline reactor 6 and a second polymerization reaction in reactor 7; wherein the reaction time of the first polymerization reaction is 1~120 min; and the reaction time of the second polymerization reaction is 1~180 min. 3) The reaction products obtained in step 2) are sequentially subjected to quenching, adsorption filtration, separation and purification and hydrogenation reaction.

[0038] In this invention, the α-olefin used to prepare mPAO is a C6-C14 olefin, which can be a single component or a mixed component. The purification of the above raw materials is carried out according to conventional purification processes in the art, including but not limited to dehydration and deoxygenation, to control the water content in the raw materials to be <50ppm and the oxide content to be <20ppm.

[0039] In this invention, at least a portion of the α-olefin feedstock is cooled to 5-45°C and then mixed with the main catalyst and the co-catalyst, respectively, to obtain a main catalyst solution and a co-catalyst solution. To ensure the stability of the catalyst during the mixing process, it is preferable to cool at least a portion of the α-olefin feedstock to 5-15°C before mixing it with the main catalyst and the co-catalyst, respectively.

[0040] To prevent temperature fluctuations in the reaction system when the catalyst is added, and to ensure that the co-catalyst is fully dissolved, the concentration of the main catalyst in the obtained main catalyst solution can be 1~8 wt‰; and the concentration of the co-catalyst in the co-catalyst solution can be 2~16 wt‰.

[0041] The remaining portion of the α-olefin feedstock described in this invention is first heated to 80-130°C and then mixed with the impurity removal catalyst, the main catalyst solution, and the co-catalyst solution to obtain a premix. To further ensure uniform mixing, the remaining α-olefin feedstock can be mixed with the impurity removal catalyst, the main catalyst solution, and the co-catalyst solution in a stirred tank. The stirring speed can be 300-1000 rpm, preferably 500-1000 rpm, and the mixing time of the premix is ​​1-180 s, preferably 1-60 s.

[0042] The premixed material described in this invention is fed into a tubular reactor 6 for the first polymerization reaction. In the tubular reactor 6, the material undergoes exponential mixing during its axial movement, enhancing radial mixing within the shell and mass and heat transfer between the inner wall and the high-viscosity fluid, resulting in a fully homogeneous mixture of the reaction system in both the axial and radial directions. Simultaneously, the residence time of the material in the tubular reactor 6 is controlled to be 1–120 min, preferably 1–20 min, and more preferably 1–15 min. This residence time coincides with the period of intense and concentrated exothermic reaction in mPAO synthesis. The heat exchange system of the tubular reactor 6 rapidly transfers this heat, preventing the reaction system from overheating and affecting the degree of polymerization of the product.

[0043] In this invention, the conditions for the first polymerization reaction may include: a temperature of 80~130℃, a pressure of 0.1~2MPa, and a reaction time of 1~15min.

[0044] The main catalyst described in this invention is a metallocene catalyst, specifically at least one of dimethicyl(N-tert-butylamino)(tetramethylcyclopentadienyl)titanium chloride, di-p-toluene-methylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium chloride, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium chloride, dimethylsilicylbis(2-methyl-4-phenylindidine)zirconium chloride, and rac-vinylbisindidinezirconium chloride.

[0045] The cocatalyst described in this invention is an organoboronide, specifically at least one of triphenylmethyltetra(pentafluorophenyl)borate, tri(pentafluorophenyl)boron, N,N-dimethylanilinetetra(pentafluorophenyl)borate, dioctadecylmethyltertiaryaminetetra(pentafluorophenyl)borate, and dihydrotallowylmethyltertiaryaminetetra(pentafluorophenyl)borate.

[0046] The impurity removal catalyst of the present invention is at least one of aluminum oxane, alkyl aluminum compound and alkyl aluminum chloride, wherein the aluminum oxane can be methyl aluminum oxane and / or modified methyl aluminum oxane; the alkyl aluminum compound can be at least one of triethylaluminum, triisobutylaluminum and trioctylaluminum; and the alkyl aluminum chloride can be at least one of monochloroethylaluminum, sesquiethylaluminum and dichloroethylaluminum.

[0047] In this invention, the product of the first polymerization reaction is sent to a reactor to continue the second polymerization reaction, and the residence time of the material in the reactor is controlled to be 1-180 min, preferably 40-80 min. The temperature during the reaction is maintained by the heating or cooling system of the reactor. To improve the heat and mass transfer efficiency during the reaction, a stirring device can be installed in the reactor. The stirring speed during the second polymerization reaction is 150-500 rpm, preferably 200-350 rpm.

[0048] In this invention, the conditions for the second polymerization reaction may include: a temperature of 80~130℃, a pressure of 0.1~2MPa, and a reaction time of 40~80min.

[0049] This invention does not impose special requirements on the quenching agent used in the quenching reaction; all quenching agents are conventional in the art, specifically at least one selected from methanol, ethanol, ethanol hydrochloride, and isopropanol, with isopropanol being preferred. The quenching reaction can be carried out in a quenching reaction vessel. To promote the mixing of the quenching agent and the reaction products, a stirring device can be installed in the vessel, with a stirring speed of 500-1000 rpm, preferably 600-800 rpm.

[0050] In this invention, the quenched material is separated and purified by adsorption filtration to remove impurities such as catalysts. The adsorbent used in the adsorption filtration is at least one of diatomaceous earth, silica gel, kaolin, and molecular sieves, preferably kaolin.

[0051] The separation and purification described in this invention includes: sending the material obtained after adsorption filtration to a primary distillation column; sending the separated gas phase to a primary gas-liquid separator; sending the liquid phase to a secondary distillation column; recovering the liquid phase separated in the primary gas-liquid separator as a quenching agent; sending the gas phase separated in the secondary distillation column to a secondary gas-liquid separator; collecting the liquid phase as a feedstock for hydrogenation reaction; and collecting the liquid phase separated in the secondary gas-liquid separator as a feedstock for α-olefins. The operating conditions of the primary distillation column include: a top temperature of 65~110℃, a bottom temperature of 160~210℃, and an operating pressure of 10~200kPa; the operating conditions of the secondary distillation column include: a top temperature of 120~200℃, a bottom temperature of 215~250℃, and an operating pressure of 2~100kPa. In this invention, the material obtained after adsorption filtration is subjected to a first-stage distillation column to remove the quencher, and then to a second-stage distillation column to remove unreacted raw materials and by-product dimers, which can then be used as raw materials for hydrogenation reaction. The separation and purification process is simple, and the recovered quencher and α-olefin raw materials can be reused in the reaction, further reducing production costs.

[0052] The hydrogenation reaction conditions described in this invention include: a pressure of 5-10 MPa, a temperature of 220-260°C, a hydrogen-to-oil ratio of 300-600:1, and a Ni-based and / or Co-based catalyst. The hydrogenation reaction product can be further fed into a three-stage distillation column to remove small molecules and water generated during hydrocracking, yielding mPAO product. The operating parameters of the three-stage distillation column include: a top temperature of 80-110°C, a bottom temperature of 170-200°C, and an operating pressure of 2-80 kPa.

[0053] In this invention, the process parameters involved in the preparation of mPAO, such as the ratio of raw materials and catalysts, and the feed flow rate, can all refer to the conventional process parameters disclosed in the art, and will not be repeated here.

[0054] The system of the present invention for carrying out the above-described method for preparing mPAO includes: A refining unit for refining α-olefin feedstock, wherein the refining unit is equipped with an α-olefin feedstock feed line; The premixing unit includes a cooler 201, a preheater 202, a main catalyst preparation tank 4, a co-catalyst preparation tank 3, and a premixing vessel 5. The main catalyst preparation tank 4 is equipped with a main catalyst feed line, the co-catalyst preparation tank 3 is equipped with a co-catalyst feed line, and the premixing vessel 5 is equipped with a purification catalyst feed line. The refining unit is connected to the cooler 201 and the preheater 202, respectively. The cooler 201 is connected to the main catalyst preparation tank 4 and the co-catalyst preparation tank 3, respectively. The main catalyst preparation tank 4, the co-catalyst preparation tank 3, and the preheater 202 are all connected to the premixing vessel 5. The polymerization reaction unit includes a pipeline reactor 6, a reaction vessel 7, and a quenching reaction vessel 801, wherein the premixing vessel 5, the pipeline reactor 6, the reaction vessel 7, and the quenching reaction vessel 801 are connected in sequence. An adsorption filtration unit includes an adsorption filter 9; the adsorption filter 9 is connected to the quenching reactor 801. The separation and purification unit includes a primary distillation column 1001, a secondary distillation column 1101, a primary gas-liquid separator 1002, and a secondary gas-liquid separator 1102; the adsorption filter 9 is sequentially connected to the primary distillation column 1001 and the secondary distillation column 1101, the primary gas-liquid separator 1002 is connected to the primary distillation column 1001, and the secondary gas-liquid separator 1102 is connected to the secondary distillation column 1101; The hydrogenation unit includes a hydrogenation reactor 14; the hydrogenation reactor 14 is connected to the secondary distillation column 1101.

[0055] To promote mixing of raw materials and catalyst, ultrasonic and / or vibration devices are preferably installed in the main catalyst preparation tank 4 and the co-catalyst preparation tank 3. Stirring devices are preferably installed in the premixing vessel 5, the reaction vessel 7, and the quenching reaction vessel 801.

[0056] The pipeline reactor 6 of the present invention may be provided with a cooling jacket on the outside to remove the heat released by the reaction, and a static mixer may be provided inside to promote uniform mixing of materials. The static mixer is at least one of SK type mixer, SX type mixer, SL type mixer and SH type mixer.

[0057] The reaction vessel 7 of the present invention is provided with a coil inside and / or a jacket outside for heating and cooling of the reaction.

[0058] The adsorption filter 9 of the present invention is filled with an adsorbent, which is at least one of diatomaceous earth, silica gel, clay and molecular sieve, preferably clay.

[0059] The hydrogenation unit of the present invention may further include a three-stage distillation column 1501 and a three-stage gas-liquid separator 1502, wherein the three-stage distillation column 1501 is connected to the hydrogenation reactor 14 and the three-stage gas-liquid separator 1502 respectively.

[0060] The three-stage distillation column 1501 described in this invention can be a precision distillation column and / or a falling film distillation column, used to remove small molecules, water, etc. generated by hydrocracking. Molecular distillation separators that can achieve the above functions are also applicable to this invention.

[0061] The following examples further illustrate the method and system for preparing mPAO according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0062] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0063] The system used to prepare mPAO in the following examples is as follows: Figure 1 As shown, the system includes: a refining reactor 101, a refining buffer tank 102, a cooler 201, a preheater 202, a catalyst preparation tank 3, a main catalyst preparation tank 4, a premixing vessel 5, a pipeline reactor 6, a reaction vessel 7, a quenching reaction vessel 801, an adsorption filter 9, a primary distillation column 1001, a primary gas-liquid separator 1002, a secondary distillation column 1101, a secondary gas-liquid separator 1102, a buffer tank 12, a hydrogenation reactor 14, a tertiary distillation column 1501, a tertiary gas-liquid separator 1103, and a product tank 16.

[0064] The main catalyst preparation tank 4 and the co-catalyst preparation tank 3 are both equipped with vibrating rods, and the premixing tank 5 and the quenching reactor 801 are both equipped with stirring paddles. The refining reactor 101 is equipped with an α-olefin feed pipeline, the main catalyst preparation tank 4 is equipped with a main catalyst feed pipeline, the co-catalyst preparation tank 3 is equipped with a co-catalyst feed pipeline, and the premixing tank 5 is equipped with a purification catalyst feed pipeline. The refining reactor 101 is connected to the cooler 201 and the preheater 202 respectively. The cooler 201, the main catalyst preparation tank 4 and the premixing tank 5 are connected in sequence. The preheater 202, the auxiliary catalyst preparation tank 3 and the premixing tank 5 are connected in sequence. The premixing vessel 5, the pipeline reactor 6, the reaction vessel 7, the quenching reaction vessel 801, the adsorption filter 9, the primary distillation column 1001, the secondary distillation column 1101, the buffer tank 12, the hydrogenation reactor 14, the tertiary distillation column 1501, and the product tank are connected in sequence. The pipeline reactor 6 is equipped with an SK-type static mixer and is externally jacketed. The reaction vessel 7 is equipped with an agitator and coils and is externally jacketed. The adsorption filter 9 is filled with adsorbent kaolin.

[0065] The top of the primary distillation column 1001 is connected to the primary gas-liquid separator 1002, the top of the secondary distillation column 1101 is connected to the secondary gas-liquid separator 1102, and the top of the tertiary distillation column 1501 is connected to the tertiary gas-liquid separator 1103. The hydrogenation reactor 14 is filled with a Ni-based catalyst.

[0066] Example 1 The specific preparation steps for mPAO using the above system are as follows: 1) The raw material 1-decene is dehydrated and deoxygenated in the refining reactor 101. After controlling the water content in 1-decene to be <50ppm and the oxide content to be <20ppm, it is divided into two parts. One part is cooled to 15°C and sent to the main catalyst preparation tank 4 and the co-catalyst preparation tank 3 respectively to prepare the main catalyst solution and co-catalyst solution with the main catalyst M rac-ethylene bis(1-indenyl)zirconium dichloride and the co-catalyst BN,N-dimethylphenylammonium tetra(pentafluorophenyl)borate. The latter part is then sent to the premixing tank 5. The other part is heated to 110°C and sent to the premixing tank 5. It is mixed with the impurity removal catalyst S triisobutylaluminum, the main catalyst solution and the co-catalyst solution at a stirring speed of 500rpm for 60s to obtain the premix. The concentration of the main catalyst M in the main catalyst solution is 5wt‰ and the concentration of the co-catalyst B in the co-catalyst solution is 11wt‰.

[0067] 2) The premix obtained in step 1) is sequentially sent to pipeline reactor 6 for the first polymerization reaction and reactor 7 for the second polymerization reaction; wherein, the temperature of the first polymerization reaction is 110℃, the pressure is 0.2MPa, the time is 10min, the stirring speed in reactor 7 is 200rpm, and the temperature of the second polymerization reaction is 110℃, the pressure is 0.2MPa, and the time is 80min.

[0068] 3) The reaction product obtained in step 2) is mixed with the quencher C isopropanol in a quenching reactor 801, with a stirring speed of 600 rpm. After the catalyst is deactivated, the quenched product is sent to an adsorption filter to remove the catalyst, and then sent to a primary distillation column 1001.

[0069] 4) The gas phase obtained by the material after separation in the first-stage distillation column 1001 is sent to the first-stage gas-liquid separator 1002, and the liquid phase is sent to the second-stage distillation column 1101. The gas phase obtained by the first-stage gas-liquid separator 1002 is sent to the outside, and the liquid phase is returned for the preparation of quenching agent C. The gas phase separated by the secondary distillation column 1101 is sent to the secondary gas-liquid separator 1102, and the liquid phase is sent to the buffer tank 12 and then enters the hydrogenation reactor 14 for hydrogenation reaction. The product of the hydrogenation reaction is sent to a three-stage distillation column 1501, where the gas phase is separated and sent to a three-stage gas-liquid separator 1103 for condensation. Both the non-condensable gas and the liquid phase are sent outside the boundary, and the liquid phase is sent to the product tank 16 for storage as mPAO product. The operating conditions for the first-stage distillation column 1001 are: top temperature 110℃, bottom temperature 180℃, and pressure 100kPa. The operating conditions for the secondary distillation column 1101 are: top temperature 140℃, bottom temperature 230℃, and pressure 2kPa. The operating conditions for the hydrogenation reaction are: pressure 6 MPa, temperature 240℃, and hydrogen-to-oil ratio 500:1. The operating conditions for the three-stage distillation column 1501 are: top temperature 100℃, bottom temperature 190℃, and pressure 2kPa.

[0070] Example 2 The specific preparation steps for mPAO using the above system are as follows: 1) The raw material 1-decene is dehydrated and deoxygenated in the refining reactor 101. After controlling the water content in 1-decene to be <50ppm and the oxide content to be <20ppm, it is divided into two parts. One part is cooled to 10℃ and sent to the main catalyst preparation tank 4 and the co-catalyst preparation tank 3 respectively to prepare the main catalyst solution and co-catalyst solution with the main catalyst M rac-ethylene bis(1-indenyl)zirconium dichloride and the co-catalyst BN,N-dimethylphenylammonium tetra(pentafluorophenyl)borate. Then it is sent to the premixing tank 5. The other part is heated to 110℃ and sent to the premixing tank 5. It is mixed with the impurity removal catalyst S triisobutylaluminum, the main catalyst solution and the co-catalyst solution at a stirring speed of 500rpm for 60s to obtain the premix. In the main catalyst solution, the concentration of the main catalyst M is 8wt‰; in the co-catalyst solution, the concentration of the co-catalyst B is 16wt‰.

[0071] 2) The premix obtained in step 1) is sequentially sent to pipeline reactor 6 for the first polymerization reaction and reactor 7 for the second polymerization reaction; wherein, the temperature of the first polymerization reaction is 110℃, the pressure is 0.5MPa, the time is 15min, the stirring speed in reactor 7 is 200rpm, and the temperature of the second polymerization reaction is 110℃, the pressure is 0.2MPa, and the time is 40min.

[0072] 3) The reaction product obtained in step 2) is mixed with the quencher C isopropanol in a quenching reactor 801, with a stirring speed of 600 rpm. After the catalyst is deactivated, the quenched product is sent to an adsorption filter to remove the catalyst, and then sent to a primary distillation column 1001.

[0073] 4) The gas phase obtained by the material after separation in the first-stage distillation column 1001 is sent to the first-stage gas-liquid separator 1002, and the liquid phase is sent to the second-stage distillation column 1101. The gas phase obtained by the first-stage gas-liquid separator 1002 is sent to the outside, and the liquid phase is returned for the preparation of quenching agent C. The gas phase separated by the secondary distillation column 1101 is sent to the secondary gas-liquid separator 1102, and the liquid phase is sent to the buffer tank 12 and then enters the hydrogenation reactor 14 for hydrogenation reaction. The product of the hydrogenation reaction is sent to a three-stage distillation column 1501, where the gas phase is separated and sent to a three-stage gas-liquid separator 1103 for condensation. Both the non-condensable gas and the liquid phase are sent outside the boundary, and the liquid phase is sent to the product tank 16 for storage as mPAO product. The operating conditions for the first-stage distillation column 1001 are: top temperature 110℃, bottom temperature 180℃, and pressure 100kPa. The operating conditions for the secondary distillation column 1101 are: top temperature 140℃, bottom temperature 230℃, and pressure 2kPa. The operating conditions for the hydrogenation reaction are: pressure 6 MPa, temperature 240℃, and hydrogen-to-oil ratio 500:1. The operating conditions for the three-stage distillation column 1501 are: top temperature 100℃, bottom temperature 190℃, and pressure 2kPa.

[0074] Example 3 The specific preparation steps for mPAO using the above system are as follows: 1) The raw material 1-decene is dehydrated and deoxygenated in the refining reactor 101. After controlling the water content in 1-decene to be <50ppm and the oxide content to be <20ppm, it is divided into two parts. One part is cooled to 5°C and sent to the main catalyst preparation tank 4 and the co-catalyst preparation tank 3 respectively to prepare the main catalyst solution and co-catalyst solution with the main catalyst M rac-ethylene bis(1-indenyl)zirconium dichloride and the co-catalyst BN,N-dimethylphenylammonium tetra(pentafluorophenyl)borate. Then it is sent to the premixing tank 5. The other part is heated to 110°C and sent to the premixing tank 5. It is mixed with the impurity removal catalyst S triisobutylaluminum, the main catalyst solution and the co-catalyst solution at a stirring speed of 800rpm for 30s to obtain the premix. In the main catalyst solution, the concentration of the main catalyst M is 2wt‰; in the co-catalyst solution, the concentration of the co-catalyst B is 5wt‰.

[0075] 2) The premix obtained in step 1) is sequentially sent to pipeline reactor 6 for the first polymerization reaction and reactor 7 for the second polymerization reaction; wherein, the temperature of the first polymerization reaction is 110℃, the pressure is 0.2MPa, the time is 3min, the stirring speed in reactor 7 is 350rpm, and the temperature of the second polymerization reaction is 110℃, the pressure is 0.2MPa, and the time is 40min.

[0076] 3) The reaction product obtained in step 2) is mixed with the quencher C isopropanol in a quenching reactor 801, with a stirring speed of 600 rpm. After the catalyst is deactivated, the quenched product is sent to an adsorption filter to remove the catalyst, and then sent to a primary distillation column 1001.

[0077] 4) The gas phase obtained by the material after separation in the first-stage distillation column 1001 is sent to the first-stage gas-liquid separator 1002, and the liquid phase is sent to the second-stage distillation column 1101. The gas phase obtained by the first-stage gas-liquid separator 1002 is sent to the outside, and the liquid phase is returned for the preparation of quenching agent C. The gas phase separated by the secondary distillation column 1101 is sent to the secondary gas-liquid separator 1102, and the liquid phase is sent to the buffer tank 12 and then enters the hydrogenation reactor 14 for hydrogenation reaction. The product of the hydrogenation reaction is sent to a three-stage distillation column 1501, where the gas phase is separated and sent to a three-stage gas-liquid separator 1103 for condensation. Both the non-condensable gas and the liquid phase are sent outside the boundary, and the liquid phase is sent to the product tank 16 for storage as mPAO product. The operating conditions for the first-stage distillation column 1001 are: top temperature 110℃, bottom temperature 180℃, and pressure 100kPa. The operating conditions for the secondary distillation column 1101 are: top temperature 140℃, bottom temperature 230℃, and pressure 2kPa. The operating conditions for the hydrogenation reaction are: pressure 6 MPa, temperature 240℃, and hydrogen-to-oil ratio 500:1. The operating conditions for the three-stage distillation column 1501 are: top temperature 100℃, bottom temperature 190℃, and pressure 2kPa.

[0078] Example 4 mPAO was prepared in accordance with the method of Example 1, except that a portion of the dehydrated and deoxygenated raw material 1-decene was cooled to 30°C.

[0079] Example 5 mPAO was prepared in accordance with the method of Example 1, except that the concentration of the main catalyst was 1 wt%.

[0080] Example 6 mPAO was prepared in accordance with the method of Example 1, except that the concentration of the co-catalyst was 1 wt%.

[0081] Example 7 mPAO was prepared in accordance with the method of Example 1, except that the time for the first polymerization reaction was 100 min.

[0082] Comparative Example 1 mPAO was prepared in accordance with the method of Example 1, except that the main catalyst and the co-catalyst were not prepared into solutions in advance, but were directly added into the premixing vessel, and the raw material 1-decene was heated and then sent to the premixing vessel.

[0083] The specific steps are as follows: In step 1), the raw material 1-decene is dehydrated and deoxygenated in the refining reactor 101. After controlling the water content in 1-decene to be <50ppm and the oxide content to be <20ppm, it is heated to 110℃ and sent to the premixing tank 5. It is then mixed with the impurity removal catalyst, the main catalyst and the co-catalyst at a stirring speed of 500rpm for 60s to obtain the premix.

[0084] Comparative Example 2 mPAO was prepared in accordance with the method of Example 1, except that no pipeline reactor was set up, and all the premix was put into the reactor for polymerization reaction.

[0085] The specific steps are as follows: In step 2), the premix obtained in step 1) is sent to reactor 7 for a second polymerization reaction; wherein the stirring speed in reactor 7 is 350 rpm and the time of the second polymerization reaction is 90 min.

[0086] Comparative Example 3 mPAO was prepared in accordance with the method of Example 1, except that no reaction vessel was set up. The premixed material was all fed into the pipeline reactor for polymerization and then sent to the quenching reaction vessel.

[0087] The specific steps are as follows: In step 2), the premix obtained in step 1) is sent to pipeline reactor 6 for the first polymerization reaction; wherein the time of the first polymerization reaction is 90 min.

[0088] 3. The mPAO prepared in Examples 1-7 and Comparative Examples 1-3 was evaluated for performance, and the results are shown in Table 1.

[0089] Table 1

[0090] As can be seen from the results in Table 1, the present invention can effectively control the temperature of the reaction system, prevent the system from running hot in the early stage of the reaction, ensure stable reaction operation, narrow molecular degree of polymerization distribution, high olefin conversion rate, and high product yield, resulting in significantly better effects.

[0091] 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 process for the preparation of mPAO, characterized in that, The method comprises: 1) mixing at least part of the refined α-olefin raw material after cooling with a main catalyst and a cocatalyst respectively to obtain a main catalyst solution and a cocatalyst solution, and mixing the remaining part of the refined α-olefin raw material after heating with a catalyst for removing impurities, the main catalyst solution and the cocatalyst solution to obtain a premix; 2) sequentially performing a first polymerization reaction in a pipeline reactor (6) and a second polymerization reaction in a reaction kettle (7) on the premix of step 1); wherein the reaction time of the first polymerization reaction is 1-120 min; and the reaction time of the second polymerization reaction is 1-180 min; 3) sequentially performing quenching, adsorption filtration, separation and purification and hydrogenation reaction on the reaction product obtained in step 2).

2. The method of claim 1, wherein, The at least part of the α-olefin raw material is mixed with the main catalyst and the cocatalyst after being cooled to 5-45 ℃.

3. The method according to claim 1 or 2, characterized in that, In the main catalyst solution, the concentration of the main catalyst is 1-8 wt‰; and / or in the cocatalyst solution, the concentration of the cocatalyst is 2-16 wt‰.

4. The method according to any one of claims 1 to 3, characterized in that, The remaining part of the α-olefin raw material is mixed with the catalyst for removing impurities, the main catalyst solution and the cocatalyst solution after being heated to 80-130 ℃.

5. The method according to any one of claims 1 to 4, characterized in that, The main catalyst is a metallocene catalyst and / or a post-metallocene catalyst; and / or The cocatalyst is an organic boron compound; and / or The catalyst for removing impurities is at least one of aluminoxane, an aluminum alkyl compound and a chloroalkyl aluminum; and / or The quenching agent used in the quenching is at least one of methanol, ethanol, hydrochloric acid ethanol and isopropanol; and / or The adsorbent used in the adsorption filtration is at least one of diatomite, silica gel, white clay and molecular sieve.

6. The method according to any one of claims 1 to 5, characterized in that, The mixing time of the premix is 1-180 s, preferably 1-60 s; and / or The conditions of the first polymerization reaction include: a temperature of 80-130 ℃, a pressure of 0.1-2 MPa and a reaction time of 1-20 min; and / or The conditions of the second polymerization reaction include: a temperature of 80-130 ℃, a pressure of 0.1-2 MPa and a reaction time of 40-80 min.

7. The method according to any one of claims 1 to 6, characterized in that, The separation and purification comprises: sending the material obtained after the adsorption filtration to a first rectifying column, sending the gas phase obtained by separation to a first gas-liquid separation tank, sending the liquid phase to a second rectifying column, recycling the liquid phase obtained by separation of the first gas-liquid separation tank as a quenching agent, sending the gas phase obtained by separation of the second rectifying column to a second gas-liquid separation tank, taking out the liquid phase as a hydrogenation reaction raw material, and taking out the liquid phase obtained by separation of the second gas-liquid separation tank as an α-olefin raw material.

8. The method according to any one of claims 1 to 7, characterized in that, The conditions of the hydrogenation reaction include: a pressure of 5-10 MPa, a temperature of 220-260 ℃, a hydrogen / oil ratio of 300-600:1, and a catalyst of a Ni-based catalyst and / or a Co-based catalyst.

9. A system for producing mPAO, characterized by The system is used for implementing the method of any one of claims 1-8, and the system comprises: a refining unit for refining the α-olefin raw material, wherein the refining unit is provided with an α-olefin raw material feeding pipeline; The premixing unit comprises a cooler (201), a preheater (202), a main catalyst configuration tank (4), a cocatalyst configuration tank (3) and a premixing kettle (5); the main catalyst configuration tank (4) is provided with a main catalyst feeding pipeline, the cocatalyst configuration tank (3) is provided with a cocatalyst feeding pipeline, and the premixing kettle (5) is provided with a deimpurity catalyst feeding pipeline; the refining unit is connected with the cooler (201) and the preheater (202) respectively, the cooler (201) is connected with the main catalyst configuration tank (4) and the cocatalyst configuration tank (3) respectively, and the main catalyst configuration tank (4), the cocatalyst configuration tank (3) and the preheater (202) are connected with the premixing kettle (5) respectively; The polymerization reaction unit comprises a pipeline reactor (6), a reaction kettle (7) and a quenching reaction kettle (801), and the premixing kettle (5), the pipeline reactor (6), the reaction kettle (7) and the quenching reaction kettle (801) are connected in sequence; The adsorption filter unit comprises an adsorption filter (9); the adsorption filter (9) is connected with the quenching reaction kettle (801); The separation and purification unit comprises a first-stage rectifying tower (1001), a second-stage rectifying tower (1101), a first-stage gas-liquid separation tank (1002) and a second-stage gas-liquid separation tank (1102); the adsorption filter (9) is connected with the first-stage rectifying tower (1001) and the second-stage rectifying tower (1101) in sequence, the first-stage gas-liquid separation tank (1002) is connected with the first-stage rectifying tower (1001), and the second-stage gas-liquid separation tank (1102) is connected with the second-stage rectifying tower (1101); The hydrogenation unit comprises a hydrogenation reactor (14); the hydrogenation reactor (14) is connected with the second-stage rectifying tower (1101).

10. The system of claim 9, wherein, The pipeline reactor (6) is provided with a static mixer, and the static mixer is at least one of an SK type mixer, an SX type mixer, an SL type mixer and an SH type mixer; and / or The pipeline reactor (6) is externally provided with a cooling jacket; and / or The reaction kettle (7) is internally provided with a coil and externally provided with a jacket; and / or The hydrogenation unit further comprises a third-stage rectifying tower (1501) and a third-stage gas-liquid separation tank (1502), and the third-stage rectifying tower (1501) is connected with the hydrogenation reactor (14) and the third-stage gas-liquid separation tank (1502) respectively.

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