A method for separating metal catalysts in polyolefin fluids

Abstract

This invention provides a method for separating metal catalysts from polyolefin fluids, comprising the following steps: S1, adding a composite terminator to the crude polyolefin product after polymerization to generate a sol-gel-like substance in the mixture, wherein the composite terminator comprises water and a halogenated hydroxyl organic compound, and the amount of the composite terminator is 1-10 wt% of the crude polyolefin product; S2, allowing the mixture treated in step S1 to settle, forming an upper organic phase, a middle flocculent phase, and a lower terminator phase; S3, filtering the upper organic phase and then stripping it to obtain light and heavy components; S4, filtering the heavy components to obtain purified polyolefin. This method does not use solid adsorbents and can remove the metal catalyst involved in coordination to below 3 ppm.

Description

Technical Field

[0001] This invention belongs to the field of polyolefin catalyst separation technology, specifically relating to a method for separating metal catalysts from polyolefin fluids. Background Technology

[0002] Numerous coordination metal compounds have been widely used as catalysts in the synthesis of functional polyolefin fluids. The crude polyolefin product after the reaction typically contains 40–150 ppm of metal elements. To avoid residual coordination metal catalysts affecting the performance of the polyolefin product, the metal catalysts involved in the coordination must be removed to below 10 ppm when obtaining high-purity polyolefin fluids.

[0003] In existing technologies, solid adsorbents are typically used to separate metal elements from polyolefins. However, this process generates a large amount of waste that cannot be recycled and pollutes the environment.

[0004] US5088941 discloses a method for removing alkylaluminum catalysts from polyolefin solutions. Molecular oxygen is introduced into the polyolefin solution containing the alkylaluminum catalyst to fully oxidize the solution into a colloidal solution. Activated carbon is then added to the system for adsorption, promoting the aggregation of nickel compounds and thus removing the metal content from the solution. This method has a long oxidation reaction time, requires a large amount of activated carbon, and is not suitable for industrial scale-up.

[0005] CN111996061A discloses a system and method for preparing mPAO separation process. The crude product obtained after the polymerization reaction is discharged into a diatomaceous earth adsorption tank and subjected to stirring and adsorption treatment at a certain temperature and time. After the polymerization product is filtered to separate the metallocene catalyst and co-catalyst, the reaction product is sent to an olefin separator. Unreacted α-olefins are distilled off from the top of the olefin separator, and the remaining product enters an oligomer separator to sequentially obtain unreacted monomers and dimers. The purified product is obtained at the bottom of the oligomer separator and is finally sent to the hydrogenation unit.

[0006] US20080020928A1 discloses a technique for removing metallocene catalysts using solid adsorbents. After the polymerization reaction is completed, 10-200 ppm of a trace amount of water or alcohol as a terminator is first added to the polyolefin mixture. Then, 1-3% of a solid adsorbent, such as solid diatomaceous earth, cellulose powder, or calcium oxide, is added to the reactor. After stirring at 1200-1600 r / min for 1-3 h, the product is filtered to obtain a purified product in which the removal rate of aluminum is ≥90% and the metal content is less than 3 ppm.

[0007] At present, the separation of mPAO catalysts in my country is carried out using solid adsorbents. The amount of solid adsorbents used is relatively large, accounting for about 1 to 3% of the crude product of mPAO base oil. After the adsorbents are used, a large amount of solid slag containing heavy metal elements is generated, which is difficult to recover and reuse, and seriously pollutes the environment after being discharged.

[0008] Therefore, developing novel polyolefin catalyst separation technologies and reducing adsorbent emissions has become a key challenge in the current development of polyolefin fluid technologies. Summary of the Invention

[0009] The purpose of this invention is to provide a method for separating metal catalysts in polyolefin fluids, which does not use solid adsorbents and can remove the metal catalysts involved in coordination to below 3 ppm.

[0010] To achieve the above objectives, the present invention provides a method for separating metal catalysts in polyolefin fluids, comprising the following steps:

[0011] S1, a composite terminator is added to the crude polyolefin product after the polymerization reaction to generate a sol-gel-like substance in the mixture. The composite terminator includes water and a halogenated hydroxyl organic compound. The amount of the composite terminator is 1 to 10 wt% of the crude polyolefin product, preferably 5 to 10 wt%.

[0012] S2, the mixture after step S1 is allowed to settle to form an upper organic phase, a middle flocculent phase and a lower terminal phase;

[0013] S3, after filtering the upper organic phase, gas stripping is performed to obtain light and heavy components;

[0014] S4, the heavy components are filtered to obtain purified polyolefin.

[0015] The method for separating metal catalysts in polyolefin fluids according to the present invention, wherein the halogenated hydroxyl organic compound is one or more of 3-chloro-1,2-propanediol, 2,3-dichloro-1-propanol, 1,3-dichloro-2-propanol, α-chloropropanetriol and (S)-4-chloro-1,3-butanediol.

[0016] The method for separating metal catalysts in polyolefin fluids according to the present invention, wherein the content of halogenated hydroxyl organic compounds in the composite terminator is 30-70 wt%, preferably 30-50 wt%.

[0017] In the method for separating metal catalysts in polyolefin fluids according to the present invention, the mixing temperature of the crude polyolefin product and the composite terminator in step S1 is 30-120°C, preferably 50-80°C.

[0018] In the method for separating metal catalysts in polyolefin fluids according to the present invention, step S3 involves stripping in a stripping tower, with the tower temperature at 200–300°C, preferably 220–260°C, and the tower top temperature controlled at 130–200°C, preferably 150–170°C.

[0019] The method for separating metal catalysts in polyolefin fluids according to the present invention, wherein the stripping gas used in step S3 includes one or more of nitrogen, helium, neon, argon, krypton, and xenon, preferably nitrogen or helium, and the stripping gas flow rate is 5 to 60 times the feed volume, preferably 15 to 60 times.

[0020] In the method for separating metal catalysts in polyolefin fluids according to the present invention, the mesh size of the filter used for filtration in steps S3 and S4 is 300 to 800 mesh.

[0021] The method for separating metal catalysts in polyolefin fluids according to the present invention further includes the steps of recovering the intermediate flocculent layer and the lower termination phase in step 2 respectively.

[0022] In the method of this invention, the hydroxyl group in the halogenated hydroxyl organic compound first undergoes a coordination reaction with alkyl aluminum or zirconium metal in the reaction system to form a metal alkoxide compound MOR. 2 With alkane gas R 1 H, metal alkoxide compound MOR 2 It reacts with water to form MOH compounds and alcohol R 2 OH, producing MOH and MOR 2 Condensation reactions occur to form large molecular MOM condensates, or self-dehydration leads to condensation reactions to form gel-like MOM condensate products. Halogen groups, being electron-withdrawing groups, are more easily dissociated to release hydrogen atoms, which then react with alkyl groups in the system to form R... 1 H causes the equilibrium to shift to the positive direction, forming more pure metal salt compounds.

[0023] Because crude polyolefin products have low density, they easily form an oil phase on the top layer. Water, with its high density, forms a terminating phase in the lower layer. Gel-like MOM condensation products have a density greater than the oil phase but less than the water phase, forming a flocculent phase between the oil and terminating phases. The flocculent phase can be further separated by filtration.

[0024] (1)MR 1 +R 2 OH→MOR 2 +R 1 H↑

[0025] (2)MOR 2 +H₂O→MOH+R 2 OH

[0026] (3)MOR2 +MOH→MO-M+R 2 OH

[0027] (4) M-OH + HO-M → MO-M + H2O

[0028] After thermal separation of residual organic solvents, water, and toluene from the trace amounts of catalyst remaining in the oil phase, the catalyst is insoluble in the base oil in the solution system and eventually precipitates in crystal form. After filtration, the purified product is obtained.

[0029] The method for separating metal elements in polyolefin fluids provided by this invention allows for the repeated recycling of the terminator, greatly reducing the amount of adsorbent used in existing technologies. The metal element removal rate is ≥95%, and the total metal content in the purified product is ≤3ppm. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of the method for separating metal catalysts in polyolefin fluids according to the present invention.

[0031] Figure 2 This is another schematic diagram of the process for separating metal catalysts in polyolefin fluids according to the present invention.

[0032] In the figure, the reference numerals are:

[0033] 1-Termination reactor; 2-Settling tank; 3-Preheater; 4-Air stripping tower; 5-Filter; 6-Product tank; 7-Condenser; 8-Light component recovery tank; 9-Oil-water separator; 10-Diaphragm pump; 11-Termination agent recovery tank. Detailed Implementation

[0034] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0035] like Figure 1 and Figure 2As shown, crude polyolefin product and composite terminator are mixed in terminator 1 through different raw material inlets, generating sol-gel-like substances in the mixture. The material in terminator 1 flows into settling tank 2, where an upper organic phase, a middle flocculent phase, and a lower terminator phase are formed. The terminator phase and flocculent phase are periodically discharged by opening the bottom discharge valve of settling tank 2, and the terminator phase and flocculent phase are recovered separately. The organic phase in settling tank 2 is a polyolefin organic fluid, which is conveyed to heater 3 for preheating after overflow. Finally, the light and heavy components are separated in stripping tower 4. The light component is recovered to light component recovery tank 8 after passing through tower top condenser 7. The heavy component separated at the bottom of stripping tower 4 is the primary purified product. The primary purified product is filtered by filter 5 to obtain purified polyolefin product, which is finally conveyed to intermediate product tank 6. When filter 5 produces a large amount of solid residue, causing a pressure drop in the system, filter 5 can be switched immediately to prevent system blockage. For more details, please refer to [link to relevant documentation]. Figure 2 The bottom of the settling tank 2 is connected to an oil-water separator 9. The terminator phase and flocculent matter are separated in the oil-water separator 9. The terminator phase in the oil-water separator 9 is recovered to the terminator recovery tank 11 by the diaphragm pump 10. When a lot of flocculent matter accumulates in the oil-water separator 9, the flow rate of the diaphragm pump 10 can be increased to recover the terminator phase. Finally, the flocculent matter is pumped to the bottom of the oil-water separator 9 and the intermediate phase of the flocculent matter is discharged.

[0036] The method of the present invention will be described below through specific embodiments.

[0037] Table 1 Raw Material Specifications and Manufacturers

[0038]

[0039] Evaluation and analysis method: ICP elemental analysis.

[0040] The specific implementation examples are as follows:

[0041] Example 1

[0042] The terminating agent consists of 50 wt% 2,3-dichloro-1-propanol and 50 wt% water.

[0043] As attached Figure 1As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: crude polyalphaolefin product rich in 50 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at 5 wt% of the crude polyalphaolefin product. Step 2: The temperature of the termination reactor is set to 50°C, and the rotation speed is set to 1200 r / min. When the termination reactor is full of solution, the mixed solution overflows into the settling tank, where two streams of material are separated. Step 3: One stream of material, including the terminator, flocculents, and a small amount of polyalphaolefin, enters the oil-water separator. The diaphragm pump flow rate is set to 50 mL / h, and the lower layer of terminator is continuously recovered to the terminator recovery tank. The other stream of material overflows from the settling tank and enters the stripping tower preheater. After being heated to 220°C, the material enters the stripping tower for light component separation. The tower temperature is 210°C, the tower top temperature is 170°C, and the nitrogen gas flow rate is 15 L / h. Two streams of material, heavy components and light components, are generated in the tower. The light components include toluene, ethanol, water, and 1-decene. After being condensed by the tower top condenser, they enter the light component recovery tank. Step 4: The heavy component material is filtered through a 600-mesh filter and enters the product recovery tank. The aluminum content of polyalphaolefin is measured to be 1.34 ppm, and the removal rate is 97.32%.

[0044] Example 2

[0045] The terminating agent consists of 30 wt% 1,3-dichloro-2-propanol and 70 wt% water.

[0046] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, in step 1: crude polyisobutylene product rich in 70 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at 6 wt% of the crude polyisobutylene product. The termination reactor temperature is set to 50°C, and the rotation speed is 1200 r / min. When the termination reactor is full, the mixed solution overflows into a settling tank, where two streams of material are separated. One stream of material, including terminator, flocculent material, and a small amount of polyisobutylene, enters the oil-water separator. Step 2: The diaphragm pump flow rate is set to 50 mL / h to continuously recover the lower layer of terminator to the terminator recovery tank. The other stream of material overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters the stripping tower for light component separation. The tower temperature is 230℃, the tower top temperature is 190℃, and the nitrogen gas flow rate is 20 L / h. Two streams of material, heavy and light components, are generated in the tower. The light component material is condensed by the tower top condenser and enters the light component recovery tank. Step 4: The heavy component material is filtered through a 350-mesh filter and enters the product recovery tank. The aluminum content was measured to be 2.35 ppm, and the removal rate was 96.64%.

[0047] Example 3

[0048] The terminator consists of 70 wt% α-chloropropanetriol and 30 wt% water.

[0049] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: Crude polyisobutylene product rich in 80 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. α-Chloropropyltriol-water termination agent is continuously added to the reactor at 10 wt% of the crude polyisobutylene product. Step 2: The termination reactor temperature is set to 70°C and the rotation speed to 1000 r / min. When the termination reactor is full, the mixed solution overflows into a settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyisobutylene, enters an oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 210℃, it enters the stripping tower for light component separation. The tower temperature is 200℃, the tower top temperature is 140℃, and the nitrogen gas flow rate is 10L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 1.78ppm, and the removal rate was 97.78%.

[0050] Example 4

[0051] The terminator consists of 60 wt% (S)-4-chloro-1,3-butanediol and 40 wt% water.

[0052] As attached Figure 1As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: crude polybutene product rich in 100 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent used is continuously added to the reactor at 10 wt% of the crude polybutene product. Step 2: The temperature of the termination reactor is set to 70°C and the rotation speed is set to 1000 r / min. When the termination reactor is full of solution, the mixed solution overflows into the settling tank, where two streams of material are separated. One stream of material, including the termination agent, flocculent matter, and a small amount of polybutene, enters the oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream of material overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters a stripping tower for light component separation. The tower temperature is 220℃, the top temperature is 120℃, and the nitrogen gas flow rate is 15L / h. Two streams of material, heavy and light components, are generated inside the tower. The light component material is condensed by the top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 500-mesh filter and then enters the product recovery tank. A sample was taken and the aluminum content was measured to be 2.84ppm, with a removal rate of 97.16%.

[0053] Example 5

[0054] The terminating agent used consists of 70 wt% (S)-4-chloro-1,3-butanediol and 30 wt% water.

[0055] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: Crude polyalphaolefin product rich in 120 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at 5 wt% of the crude polybutene product. Step 2: The temperature of the termination reactor is set to 60°C and the rotation speed is set to 1000 r / min. When the termination reactor is full of solution, the mixed solution overflows into the settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyalphaolefin, enters the oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters the stripping tower for light component separation. The tower temperature is 220℃, the tower top temperature is 130℃, and the nitrogen gas flow rate is 15L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 2.84ppm, and the removal rate was 97.63%.

[0056] Example 6

[0057] The terminating agent used consists of 55 wt% (S)-4-chloro-1,3-butanediol and 45 wt% water.

[0058] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: Crude polyalpha-olefin product rich in 120 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at 1 wt% of the crude polybutene product. Step 2: The temperature of the termination reactor is set to 30°C and the rotation speed to 800 r / min. When the termination reactor is full of solution, the mixed solution overflows into the settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyalpha-olefin, enters the oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 270℃, it enters the stripping tower for light component separation. The tower temperature is 250℃, the tower top temperature is 130℃, and the nitrogen gas flow rate is 25L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 1.85ppm, and the removal rate was 98.46%.

[0059] Example 7

[0060] The terminating agent used consists of 55 wt% 3-chloro-1,2-propanediol and 45 wt% water.

[0061] As attached Figure 1As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: crude polyalphaolefin product rich in 120 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at a dosage of 1.2 wt% of crude polybutene product. Step 2: The temperature of the termination reactor is set to 120°C and the rotation speed is set to 800 r / min. When the termination reactor is full of solution, the mixed solution overflows into a settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyalphaolefin, enters an oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters the stripping tower for light component separation. The tower temperature is 210℃, the tower top temperature is 160℃, and the nitrogen gas flow rate is 30L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 1.45ppm, and the removal rate was 98.79%.

[0062] Comparative Example 1

[0063] The terminating agent used was 50 wt% ethanol and 50 wt% water.

[0064] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: crude polyalphaolefin product rich in 120 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at a dosage of 1.2 wt% of crude polybutene product. Step 2: The temperature of the termination reactor is set to 120°C and the rotation speed is set to 800 r / min. When the termination reactor is full of solution, the mixed solution overflows into a settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyalphaolefin, enters an oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters the stripping tower for light component separation. The tower temperature is 220℃, the tower top temperature is 160℃, and the nitrogen gas flow rate is 30L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 17.85ppm, and the removal rate was 85.12%.

[0065] Comparative Example 2

[0066] The terminating agent used was 50 wt% ethanol and 50 wt% water.

[0067] As attached Figure 1 As shown, the separation system described above is used to purify polyolefin products. Specifically, step 1: Crude polyalpha-olefin product rich in 120 ppm aluminum is continuously fed into the termination reactor at a rate of 500 mL / h. The termination agent is continuously added to the reactor at 5 wt% of the crude polybutene product. Step 2: The temperature of the termination reactor is set to 120°C and the rotation speed is set to 800 r / min. When the termination reactor is full of solution, the mixed solution overflows into the settling tank, where two streams are separated. One stream, including the termination agent, flocculent matter, and a small amount of polyalpha-olefin, enters the oil-water separator. The diaphragm pump flow rate is set to 30 mL / h, and the lower layer of termination agent is continuously recovered to the termination agent recovery tank. The other stream overflows from the settling tank and enters the stripping tower preheater. Step 3: After the material is heated to 240℃, it enters the stripping tower for light component separation. The tower temperature is 210℃, the tower top temperature is 160℃, and the nitrogen gas flow rate is 30L / h. Two streams of material, heavy component and light component, are generated in the tower. The light component material is condensed by the tower top condenser and then enters the light component recovery tank. Step 4: The heavy component material is filtered through a 400-mesh filter and then enters the product recovery tank. The aluminum content was measured to be 19.85ppm, and the removal rate was 83.45%.

[0068] Comparative Example 3

[0069] The crude polyalphaolefin product rich in 120 ppm aluminum was heated to 110°C, and diatomaceous earth filter aid with a base oil content of 2 wt% was added. After stirring evenly for 2 hours, the mixture of base oil and diatomaceous earth was filtered through a 300-mesh filter to obtain the purified product. The aluminum content was measured to be 16.34 ppm, and the aluminum removal rate was calculated to be 86.38%.

[0070] Comparative Example 4

[0071] The crude polyalphaolefin product rich in 120 ppm aluminum was heated to 110°C, and 1.2 wt% diatomaceous earth filter aid was added as base oil. After stirring evenly for 2 hours, the mixture of base oil and diatomaceous earth was filtered through a 300-mesh filter to obtain the purified product. The aluminum content was measured to be 23.69 ppm, and the aluminum removal rate was calculated to be 80.25%.

[0072] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for separating metal catalysts from polyolefin fluids, characterized in that, Includes the following steps: S1, A composite terminator is added to the crude polyolefin product after the polymerization reaction to generate a sol-gel-like substance in the mixture. The composite terminator comprises water and a halogenated hydroxyl organic compound, and the amount of the composite terminator is 1-10 wt% of the crude polyolefin product. S2, the mixture after step S1 is allowed to settle to form an upper organic phase, a middle flocculent phase and a lower terminal phase; S3, after filtering the upper organic phase, gas stripping is performed to obtain light and heavy components; S4, the heavy components are filtered to obtain purified polyolefin; The halogenated hydroxyl organic compound is one or more of 3-chloro-1,2-propanediol, 2,3-dichloro-1-propanol, 1,3-dichloro-2-propanol and (S)-4-chloro-1,3-butanediol. The content of halogenated hydroxyl organic compounds in the composite terminator is 30~70 wt%.

2. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that, In step S1, the mixing temperature of the crude polyolefin product and the composite terminator is 30~120℃.

3. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that, In step S3, the stripping is carried out in a stripping tower, with the temperature inside the tower being 200~300℃ and the temperature at the top of the tower being controlled at 130~200℃.

4. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that, The stripping gas used in step S3 includes one or more of nitrogen, helium, neon, argon, krypton, and xenon, and the flow rate of the stripping gas is 5 to 60 times the feed volume.

5. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that, The mesh size of the filter used in steps S3 and S4 is 300~800 mesh.

6. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that, It also includes the steps of separately recovering the intermediate layer flocculents and the lower layer termination phase in step 2.

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