Method for separating metal catalyst from polyolefin fluid

Abstract

The invention provides a method for separating a metal catalyst from a polyolefin fluid, which comprises the following steps: S1, adding a composite terminator into a polyolefin crude product after polymerization reaction to generate sol-gel substances in the mixture, the composite terminator comprising water and a halogenated hydroxyl organic compound, and the halogenated hydroxyl organic compound comprising water and a halogenated hydroxyl organic compound; the dosage of the composite terminator is 1-10 wt% of the polyolefin crude product; s2, settling the mixture treated in the step S1 to form an upper-layer organic phase, a middle-layer floccule and a lower-layer termination phase; s3, filtering the upper-layer organic phase, and carrying out gas stripping to obtain a light component and a heavy component; and S4, filtering the heavy component to obtain purified polyolefin. According to the method, a solid adsorbent is not used, and the metal catalyst participating in coordination can be removed to 3 ppm or below.

Description

Technical Field

[0001] The invention belongs to the technical field of polyolefin catalyst separation, and in particular relates to a method for separating a metal catalyst from a polyolefin fluid. Background Art

[0002] A large number of coordinated metal compounds have been widely used as catalysts in the field of synthesizing functional polyolefin fluids. The crude polyolefin product after the reaction usually contains 40-150ppm of metal elements. In order to avoid the residual coordinated metal catalyst affecting the performance of the polyolefin product, the metal catalyst involved in the coordination must be removed to less than 10ppm when obtaining high-purity polyolefin fluids.

[0003] In the prior art, solid adsorbents are usually used to separate metal elements from polyolefins. During the separation process, a large amount of waste residue is generated which cannot be recycled and pollutes the environment.

[0004] US5088941 discloses a method for removing alkyl aluminum catalyst from polyolefin solution. Molecular oxygen is introduced into the polyolefin solution containing alkyl aluminum catalyst to fully oxidize the solution system to form a glue solution, and then activated carbon is added into the system for adsorption to promote the coagulation of nickel compounds, thereby removing the metal content in the solution system. This method has a long oxidation reaction time, requires the use of 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 adsorption treatment at a certain temperature and time. After the polymerization product is separated from the metallocene catalyst and the co-catalyst by a filter, the reaction product is sent to an olefin separator, and the unreacted α-olefin is evaporated from the top of the olefin separator. The remaining product enters an oligomer separator, and unreacted monomers and dimers are obtained in turn. The purified product is obtained at the bottom of the oligomer separator, and the purified product is finally sent to the hydrogenation unit.

[0006] US20080020928A1 discloses a technology for removing metallocene catalysts with solid adsorbents. After the polymerization reaction is completed, a small amount of water or alcohol or other terminators such as 10-200 ppm is added to the mixed solution of polyolefins, and then 1-3% of solid adsorbents such as solid diatomaceous earth, cellulose powder or calcium oxide are added to the reactor. After stirring at 1200-1600 r / min for 1-3 hours, the product is filtered to obtain a purified product, in which the removal rate of metal aluminum element is ≥90% and the metal content is less than 3 ppm.

[0007] At present, the separation of mPAO catalysts in my country is all done by solid adsorbents. The amount of solid adsorbents used is large, accounting for about 1-3% of the crude mPAO base oil product. After use, the adsorbent produces a large amount of solid residue containing heavy metal elements, which is difficult to recycle and reuse, and seriously pollutes the environment after discharge.

[0008] Therefore, developing new polyolefin catalyst separation technologies and reducing adsorbent emissions have become key challenges in the current development of polyolefin fluid technology. Summary of the invention

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

[0010] To achieve the above object, the present invention provides a method for separating a metal catalyst from a polyolefin fluid, comprising the following steps:

[0011] S1, adding a composite terminator to the crude polyolefin product after the polymerization reaction to generate a sol-gel substance in the mixture, wherein the composite terminator comprises water and a halogenated hydroxy organic compound, and the amount of the composite terminator is 1 to 10 wt % of the crude polyolefin product, preferably 5 to 10 wt %;

[0012] S2, sedimenting the mixture after the treatment in step S1 to form an upper organic phase, an intermediate flocculent layer and a lower terminal phase;

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

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

[0015] In the method for separating metal catalysts in polyolefin fluids of the present invention, the halogenated hydroxy organic compound is one or more of 3-chloro-1,2-propylene glycol, 2,3-dichloro-1-propanol, 1,3-dichloro-2-propanol, α-chloroglycerol and (S)-4-chloro-1,3-butanediol.

[0016] In the method for separating metal catalysts from polyolefin fluids of the present invention, the content of halogenated hydroxy organic compounds in the composite terminator is 30-70wt%, preferably 30-50wt%.

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

[0018] In the method for separating metal catalysts from polyolefin fluids of the present invention, the gas stripping in step S3 is carried out in a gas stripping tower, the temperature in the tower is 200-300°C, preferably 220-260°C, and the tower top temperature is controlled at 130-200°C, preferably 150-170°C.

[0019] In the method for separating metal catalysts from polyolefin fluids of the present invention, the stripping gas used in step S3 comprises 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 volume of the feed, preferably 15 to 60 times.

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

[0021] The method for separating metal catalysts from polyolefin fluids of the present invention further comprises the steps of separately recovering the middle layer floccules and the lower layer termination phase in step 2.

[0022] In the method of the present invention, the hydroxyl group in the halogenated hydroxyl organic compound is firstly used to coordinate with the 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 Reacts with water to form MOH compound and alcohol R 2 OH, generated MOH and MOR 2 The condensation reaction forms a macromolecular MOM condensate, or the self-dehydration condensation reaction forms a gel-like MOM condensation product. The halogen group is an electron-withdrawing group that is more likely to remove and dissociate hydrogen atoms and form R with the alkyl group in the system. 1 H, causes the equilibrium to shift positively, forming more metal pure salt compounds.

[0023] Since the density of the crude polyolefin product is low, an oil phase is easily formed at the top. The water density is high, and a termination phase is formed at the bottom. The gel-like MOM condensation product has a higher density than the oil phase and a lower density than the water phase, and a flocculent phase is formed between the oil phase and the termination phase. The flocculent can be further separated by filtration.

[0024] (1)MR 1 +R 2 OH→MOR 2 +R 1 H↑

[0025] (2)MOR 2 +H 2 O→MOH+R 2 OH

[0026] (3)MOR 2 +MOH→MO-M+R 2 OH

[0027] (4)M-OH+HO-M→MO-M+H 2 O

[0028] After the residual organic solvent, water and toluene are separated by heat from the trace catalyst remaining in the oil phase, the catalyst is insoluble in the base oil in the solution system and finally precipitates in the form of crystals, and a purified product is obtained after filtration.

[0029] The method for separating metal elements from polyolefin fluid provided by the present invention can reuse the terminator, greatly reducing the amount of adsorbent used in the prior art, with a metal element removal rate of ≥95% and a total metal content of ≤3ppm in the obtained purified product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is a schematic flow diagram of the method for separating the metal catalyst in the polyolefin fluid according to the present invention;

[0031] Figure 2 The present invention is another schematic flow diagram of the method for separating metal catalysts from polyolefin fluids.

[0032] In the figure, reference numerals:

[0033] 1-termination reactor; 2-sedimentation tank; 3-preheater; 4-gas stripping tower; 5-filter; 6-product tank; 7-condenser; 8-light component recovery tank; 9-oil-water separation tank; 10-diaphragm pump; 11-terminator recovery tank. DETAILED DESCRIPTION

[0034] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0035] like Figure 1 and Figure 2As shown, the crude polyolefin product and the composite terminator are mixed in the termination reactor 1 through different raw material inlets, and a sol-gel substance is generated in the mixture. The material in the termination reactor 1 flows into the settling tank 2, and an upper organic phase, an intermediate flocculent layer and a lower termination phase are formed in the settling tank 2. The termination phase and the flocculent are discharged regularly by opening the lower discharge valve of the settling tank 2, and the termination phase and the flocculent are recovered separately. The organic phase in the settling tank 2 is a polyolefin organic fluid, which is transported to the heater 3 for preheating after overflow, and finally the light and heavy components are separated in the stripping tower 4, wherein the light component is recovered to the light component recovery tank 8 after passing through the top condenser 7; the heavy component separated at the bottom of the stripping tower 4 is the primary purification product, and the primary purification product is filtered through the filter 5 to obtain a purified polyolefin product, which is finally transported to the intermediate product tank 6. When the filter 5 produces a lot of solid slag, the filter 5 can be switched immediately after a pressure drop is generated in the system to prevent the system from being blocked. For more details, please refer to Figure 2 The bottom of the sedimentation tank 2 is connected to an oil-water separation tank 9, and the termination phase and the flocs are separated in the oil-water separation tank 9. The termination phase in the oil-water separation tank 9 is recovered to the terminator recovery tank 11 through a diaphragm pump 10. When a large amount of flocs accumulate in the oil-water separation tank 9, the termination phase can be recovered by increasing the flow rate of the diaphragm pump 10. Finally, after the flocs are pumped to the bottom of the oil-water separation tank 9, the floc intermediate phase is discharged.

[0036] The method of the present invention is described below by means of specific examples.

[0037] Table 1 Raw material specifications and manufacturers

[0038]

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

[0040] The specific embodiments obtained are as follows:

[0041] Example 1

[0042] The terminator comprises: 50 wt% 2,3-dichloro-1-propanol and 50 wt% water.

[0043] As attached Figure 1As shown, the separation system is used to purify polyolefin products. Specifically, step 1: the crude polyalphaolefin product rich in 50ppm aluminum element is continuously fed into the termination reactor at a rate of 500mL / h, and the terminator used is continuously added to the reactor according to 5wt% of the crude polyalphaolefin product. Step 2: the temperature of the termination reactor is set to 50°C and the speed is set to 1200r / min. When the termination reactor is filled with the solution, the mixed solution overflows into the sedimentation tank, and two streams of materials are separated in the sedimentation tank. Step 3: A stream of material including terminator, flocculent and a small amount of polyα-olefin enters the oil-water separator, and the diaphragm pump flow rate is set to 50mL / h, and the lower layer terminator is continuously recovered to the terminator recovery tank; another stream of material enters the gas stripping tower preheater after overflowing from the sedimentation tank, and the material is heated to 220°C and then enters the gas stripping tower for light component separation, wherein the temperature in the tower is 210°C, the temperature at the top of the tower is 170°C, and the nitrogen gas flow rate is 15L / h, and two streams of heavy component and light component are produced in the tower, wherein the light component material includes: toluene, ethanol, water, 1-decene, and enters the light component recovery tank after condensation in the top condenser; Step 4: The heavy component material is filtered through a 600-mesh filter and enters the product recovery tank. The polyα-olefin aluminum content is measured by sampling to be 1.34ppm, and the removal rate is 97.32%.

[0044] Example 2

[0045] The terminator comprises: 30 wt % 1,3-dichloro-2-propanol and 70 wt % water.

[0046] As attached Figure 1 As shown, the separation system is used to purify polyolefin products. Specifically, step 1: the crude polyisobutylene product rich in 70ppm aluminum element is continuously fed into the termination reactor at a rate of 500mL / h, and the terminator used is continuously added to the reactor according to 6wt% of the crude polyisobutylene product, and the temperature of the termination reactor is set to 50°C and the speed is set to 1200r / min. When the termination reactor is full of the solution, the mixed solution overflows into the sedimentation tank, and two streams of materials are separated in the sedimentation tank. A stream of material including terminator, flocculent and a small amount of polyisobutylene enters the oil-water separator, step 2: set the diaphragm pump flow rate to 50mL / h, and continuously recover the lower layer terminator to the terminator recovery tank; another stream of material enters the stripping tower preheater after overflowing from the sedimentation tank, step 3: after the material is heated to 240°C, it enters the stripping tower for light component separation, wherein the temperature in the tower is 230°C, the temperature at the top of the tower is 190°C, and the nitrogen gas flow rate is 20L / h, and two streams of heavy component and light component are produced in the tower, wherein the light component material is condensed by the 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, and the aluminum content is measured to be 2.35ppm by sampling, and the removal rate is: 96.64%.

[0047] Example 3

[0048] The terminator comprises: 70 wt % of α-chloropropylene glycol and 30 wt % of water.

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

[0050] Example 4

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

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

[0053] Example 5

[0054] The terminator used comprises: 70 wt % (S)-4-chloro-1,3-butanediol and 30 wt % water.

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

[0056] Example 6

[0057] The terminator used comprises: 55 wt% (S)-4-chloro-1,3-butanediol and 45 wt% water.

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

[0059] Example 7

[0060] The terminator used comprises: 55 wt% 3-chloro-1,2-propylene glycol and 45 wt% water.

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

[0062] Comparative Example 1

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

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

[0065] Comparative Example 2

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

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

[0068] Comparative Example 3

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

[0070] Comparative Example 4

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

[0072] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for separating a metal catalyst from a polyolefin fluid, characterized in that: The following steps are involved: S1, adding a composite terminator to the crude polyolefin product after the polymerization reaction to generate a sol-gel substance in the mixture, wherein the composite terminator comprises water and a halogenated hydroxy organic compound, and the amount of the composite terminator is 1 to 10 wt % of the crude polyolefin product; S2, sedimenting the mixture after the treatment in step S1 to form an upper organic phase, an intermediate flocculent layer and a lower terminal phase; S3, filtering and stripping the upper organic phase to obtain light components and heavy components; S4, filtering the heavy components to obtain purified polyolefin.

2. The method for separating metal catalysts from polyolefin fluid according to claim 1, characterized in that: The halogenated hydroxy organic compound is one or more of 3-chloro-1,2-propanediol, 2,3-dichloro-1-propanol, 1,3-dichloro-2-propanol, α-chloroglycerol and (S)-4-chloro-1,3-butanediol.

3. The method for separating metal catalysts from polyolefin fluids according to claim 1, characterized in that: The content of the halogenated hydroxy organic compound in the composite terminator is 30-70 wt %.

4. The method for separating metal catalysts from polyolefin fluid 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°C.

5. The method for separating metal catalysts from polyolefin fluid according to claim 1, characterized in that: In step S3, the gas stripping is carried out in a gas stripping tower, the temperature in the tower is 200-300°C, and the temperature at the top of the tower is controlled at 130-200°C.

6. The method for separating metal catalysts from polyolefin fluid 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 stripping gas flow rate is 5 to 60 times the volume of the feed.

7. The method for separating metal catalysts from polyolefin fluid according to claim 1, characterized in that: The mesh size of the filter used for filtration in step S3 and step S4 is 300 to 800 meshes.

8. The method for separating metal catalysts from polyolefin fluid according to claim 1, characterized in that: The method also includes the steps of separately recovering the middle layer floccules and the lower layer termination phase in step 2.

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