Process for the dissolution of ziegler-natta granular polyolefin catalysts and synthesis plant

Abstract

The application relates to the field of catalyst preparation, and discloses a dissolving solution treatment method and a synthesis device for Z-N particle type polyolefin catalysts. The dissolving solution treatment method comprises the following steps: under a closed condition, sequentially filtering and centrifuging a raw material dissolving solution, so that the content of insoluble solid impurities in the centrifugal dissolving solution obtained through centrifugation is less than 10 mg / L, and then the centrifugal dissolving solution is used for synthesizing the Z-N particle type polyolefin catalyst; wherein the raw material dissolving solution is a toluene solution containing magnesium chloride. The method and the device can save the operation time of dissolving solution treatment, optimize the synthesis reaction process, reduce the labor intensity, and improve the performance of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, specifically to a solution treatment method for ZN particulate polyolefin catalysts and a synthesis apparatus for ZN particulate polyolefin catalysts. Background Technology

[0002] ZN (Ziegler-Natta) granular polyolefin catalyst is a high-efficiency polypropylene catalyst. This product is characterized by high activity and strong polymerization orientation. Furthermore, by adopting different process control schemes and selecting different electron donors, the polymerization performance of this product can be adjusted to suit various polyolefin production plants for the production of polypropylene products with different properties. Currently, this product is widely used in various polypropylene production plants both domestically and internationally.

[0003] The production process of this product employs a one-step co-precipitation method. Through a chemical reaction, a stable complexed compound, primarily composed of anhydrous magnesium chloride, dissolved in toluene solvent, precipitates a polypropylene catalyst with active magnesium chloride as the carrier, simultaneously loading active metal compounds and electron-donating agents. Since propylene polymerization largely involves the amplification and replication of catalyst particle morphology, particle shape and the ability to bind with active metal compounds and electron-donating agents are crucial factors influencing catalyst performance. Therefore, the complexation precipitation process is a key control step in catalyst preparation. The quality of the toluene-complex homogeneous solution (solution) formed after the coarsely processed anhydrous magnesium chloride solid powder and additives are dispersed, homogenized, and complexed in toluene solvent, and finally dissolved in the solvent, plays a critical role in subsequent particle re-forming and the final catalyst performance.

[0004] During the preparation and rough processing of anhydrous magnesium chloride, it is unavoidable that some metallic and non-metallic impurities will be introduced. Some of these metallic impurities can be adsorbed by a magnet, while the rest cannot be adsorbed by a magnet and remain suspended in the solution as particulate matter. These solid particulate impurities are mostly 0.1-4 μm in size and have irregular morphology. When they enter the catalyst synthesis and preparation process, they will cause abnormalities such as abnormal catalyst particle morphology, non-catalyst aggregates, and catalyst particle agglomeration, which will affect the catalyst polymerization performance (such as explosive agglomeration in the reactor and polymer clumping) and industrial application performance (such as catalyst transport performance and ultrafine polymer particles).

[0005] To remove such solid particulate impurities, current methods often employ long-term gravity sedimentation and magnetic filtration, supplemented by particle grading and sieving of the produced catalyst to remove any remaining impurities. However, gravity sedimentation requires prolonged storage, resulting in extremely low separation efficiency. Furthermore, when using an insertable suction pipette to transfer liquid, particulate impurities deposited at the bottom of the container are carried aloft by the liquid flow, failing to achieve effective separation. Magnetic filters often fail to remove irregular, fine particles, either permeating the filter media or forming a dense filter cake, leading to extremely low particle removal efficiency. Conventional multi-layer 400-mesh wire mesh stacked fixed filters suffer from high filtration penetration and a filtrate solid content of 0.15–0.25 wt%, easily causing filter cake blockage, flow interruption, and filter media damage and leakage, hindering efficient separation and resulting in high labor intensity. Summary of the Invention

[0006] The purpose of this invention is to overcome the problem of high content of solid particulate impurities in the raw material solution in the prior art, and to provide a solution treatment method for ZN particulate polyolefin catalysts and a synthesis device for ZN particulate polyolefin catalysts.

[0007] Closed-circuit centrifuges are suitable for particles with slow settling rates, small particle diameters, and solid particles that are compressible after stacking and can form a dense filter cake. They can separate solid-liquid mixtures that are unsuitable for separation using gravity sedimentation or filtration methods. These closed-circuit centrifuges are widely used in environmental protection, food and beverage processing, and have also been seen in inorganic and basic organic chemical industries.

[0008] The inventors of this invention conducted in-depth research on the synthesis of ZN particulate polyolefin catalysts and discovered that by controlling the content of insoluble solid impurities in the solution used for synthesis to below 10 mg / L through filtration and centrifugation, the operation time for solution treatment can be saved, the synthesis reaction process can be optimized, labor intensity can be reduced, and the performance of the catalyst can be improved.

[0009] To achieve the above objectives, the present invention provides a method for treating a solution of ZN particulate polyolefin catalyst. The method includes: under closed conditions, sequentially filtering and centrifuging the raw material solution to reduce the content of insoluble solid impurities in the centrifuged solution to below 10 mg / L, and then using the centrifuged solution for the synthesis of ZN particulate polyolefin catalyst; wherein the raw material solution is a toluene solution containing magnesium chloride.

[0010] Preferably, the content of insoluble solid impurities in the filtered solution obtained by filtration is less than 100 mg / L.

[0011] Preferably, the content of insoluble solid impurities in the centrifuged solution obtained by centrifugation is less than 5 mg / L, and more preferably 0 to 2 mg / L.

[0012] Preferably, the filter used in the filtration is a 60-200 mesh screen.

[0013] Preferably, the filtration is performed using a magnetic coarse filter.

[0014] Preferably, the centrifugation speed is 5000 rpm or higher, and more preferably 6000 rpm or higher.

[0015] Preferably, the centrifugation process has a flow rate of less than 2000 L / hr, and more preferably 1000 to 1500 L / hr.

[0016] Preferably, the concentration of magnesium chloride in the raw material solution is 3-10 wt%, more preferably 4-7 wt%.

[0017] Preferably, the raw material solution further contains one or more auxiliaries selected from epoxy compounds, ester compounds, acid anhydride compounds, alcohol compounds, and silicate ester compounds.

[0018] The second aspect of the present invention provides a synthesis apparatus for ZN particulate polyolefin catalysts, the synthesis apparatus comprising a dissolving vessel (1), a coarse filter (2), a closed centrifuge (3), and a synthesis vessel (4) connected in sequence and sealed together.

[0019] The dissolving vessel (1) is used to dissolve the raw materials to obtain a raw material solution;

[0020] The coarse filter (2) is used to filter the raw material solution to obtain a filtered solution;

[0021] The closed centrifuge (3) is used to centrifuge the filtered solution so that the content of insoluble solid impurities in the centrifuged solution is less than 10 mg / L.

[0022] The synthesis vessel (4) is used to synthesize ZN particulate polyolefin catalysts using the centrifuged dissolution solution.

[0023] Preferably, the closed centrifuge (3) uses a sealing ring made of fluororubber, silicone rubber or ether rubber.

[0024] Preferably, the coarse filter (2) ensures that the content of insoluble solid impurities in the filtered solution is below 100 mg / L.

[0025] Preferably, the closed centrifuge (3) ensures that the content of insoluble solid impurities in the centrifuged solution is below 5 mg / L, preferably 0 to 2 mg / L.

[0026] The third aspect of the present invention provides the application of the above-described method for treating the solution of ZN particulate polyolefin catalyst or the above-described synthesis apparatus for ZN particulate polyolefin catalyst in the synthesis of ZN particulate polyolefin catalyst, preferably in the synthesis of ZN particulate polypropylene catalyst.

[0027] Through the above technical solution, the solution treatment method and synthesis equipment of the present invention, by sequentially filtering and centrifuging the solution, and by applying a centrifugal field to the dissolved pre-reaction solution, insoluble particulate impurities that have not participated in the reaction and cannot be dissolved by the solvent toluene can be separated. The clean solution obtained after separation can be used for the synthesis and preparation of ZN particulate polypropylene catalysts. This clean solution can effectively reduce the generation of irregular and impurity solid particles in catalyst preparation, which helps to avoid catalyst jamming and clogging during the application of the polymerization device, and is more suitable for the application of the catalyst in the preparation of ZN particulate polyolefin catalysts. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the synthesis equipment for ZN particulate polyolefin catalysts according to the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1. Dissolving vessel 2. Coarse filter 3. Closed-loop centrifuge

[0031] 4. Synthesis kettle; 5. Liquid inlet controller; 6. Dissolved liquid delivery pipe

[0032] 7. Centrifuge inlet pipe; 8. Synthesis reactor inlet pipe Detailed Implementation

[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] The first aspect of the present invention provides a method for treating a solution of ZN particulate polyolefin catalyst. The method includes: under closed conditions, sequentially filtering and centrifuging the raw material solution to reduce the content of insoluble solid impurities in the centrifuged solution to below 10 mg / L, and then using the centrifuged solution for the synthesis of ZN particulate polyolefin catalyst; wherein the raw material solution is a toluene solution containing magnesium chloride.

[0035] In this invention, the content of insoluble solid impurities is determined by using infrared pulse light scattering (light attenuation) to quantitatively characterize the content of suspended particulate matter in the liquid. For example, the G966 suspended matter detector manufactured by Shandong Greencare Precision Instruments Co., Ltd. can be used, and the standard solution is distilled water.

[0036] The ZN particulate polyolefin catalyst can be a ZN particulate polypropylene catalyst or a ZN particulate polybutene catalyst, preferably a ZN particulate polypropylene catalyst.

[0037] In this invention, the solution obtained by dissolving the raw materials is called the "raw material solution," which has not undergone filtration and centrifugation; the liquid phase obtained after filtration is called the "filtered solution"; and the liquid phase obtained after centrifugation is called the "centrifuged solution." The only difference between these three solutions is the content of solid impurities. For ease of description, these three solutions are collectively referred to as solutions in this invention.

[0038] According to the present invention, preferably, the content of insoluble solid impurities in the filtered solution obtained by filtration is less than 100 mg / L, and more preferably less than 80 mg / L.

[0039] According to the present invention, preferably, the content of insoluble solid impurities in the centrifuged solution obtained by centrifugation is less than 5 mg / L, more preferably 0 to 2 mg / L, and particularly preferably 0 mg / L.

[0040] In this invention, the raw material solution is used to prepare a polypropylene catalyst via a one-step co-precipitation method. Specifically, a stable complexed compound, primarily composed of anhydrous magnesium chloride, dissolved in toluene solvent, is used for the synthesis reaction to precipitate a polyolefin catalyst supported on active magnesium chloride and simultaneously supported on active titanium compounds and internal electron-donating agents such as esters and alcohols. The solid impurities in the raw material solution mainly originate from the magnesium chloride raw material, specifically including metallic and non-metallic impurities. The solid impurities in the raw material solution are typically 0.4–1 wt%, primarily consisting of solid impurities with a particle size of 0.1–4 μm. According to some specific embodiments of this invention, the content of insoluble solid impurities in the raw material solution is 0.4–1 wt%, the particle size of the solid impurities is 0.1–4 μm, and the solid density is 0.15–7.8 g / cm³. 3 .

[0041] In this invention, in addition to magnesium chloride, the raw material solution also contains one or more auxiliaries selected from epoxy compounds, ester compounds, acid anhydride compounds, alcohol compounds, and silicate ester compounds. The raw material solution of this invention is a toluene-complex homogeneous solution formed by dispersing, homogenizing, complexing, and finally dissolving anhydrous magnesium chloride solid powder and the aforementioned auxiliaries in toluene solvent.

[0042] In the additives used in this invention, the epoxy compounds can be, for example, propylene oxide, epichlorohydrin, etc.; the ester compounds can be, for example, tributyl phosphate, etc.; the anhydride compounds can be, for example, phthalic anhydride, etc.; and the silicate compounds can be, for example, ethyl silicate, tetraethyl orthosilicate, etc.

[0043] According to a preferred embodiment of the present invention, the additive is epichlorohydrin, tributyl phosphate, and phthalic anhydride. More preferably, the weight ratio of magnesium chloride, epichlorohydrin, tributyl phosphate, and phthalic anhydride is 1:0.5-2:2-3:0.1-0.4, for example, 1:0.75:2.5:0.25.

[0044] The concentration of magnesium chloride in the raw material solution is 3-10 wt%, preferably 4-7 wt%, for example, 5 wt%.

[0045] According to some preferred embodiments of the present invention, the filter screen used in the filtration is 60 to 200 mesh. From the perspective of separating metallic impurities, it is preferable to use a magnetic coarse filter for the filtration. Furthermore, to improve the filtration efficiency, it is preferable to use a pressure filtration method. In pressure filtration, the delivery pressure can be 0.15 MPa or higher, preferably 0.2 to 0.25 MPa, and nitrogen can be used as the pressure source for filtration.

[0046] According to some preferred embodiments of the present invention, the centrifugation conditions include a rotation speed of 5000 rpm or higher, preferably 6000 rpm or higher, and more preferably 6500 rpm or higher. By performing continuous centrifugation under the above conditions, solid impurities in the raw material solution can be efficiently separated, and a centrifuged solution meeting the requirements can be obtained for the synthesis of Zn particulate polyolefin catalysts.

[0047] To ensure that the raw material solution does not come into contact with air and water during the filtration and centrifugation processes described above, the filtration and centrifugation processes are carried out under completely enclosed conditions.

[0048] According to the present invention, the solution treatment method further includes controlling the temperature of the solution to below 40°C, preferably 20-30°C, during the treatment process. Specifically, the temperature of the solution can be controlled by providing a cooling jacket on the device or component used for centrifugation, filtration, and / or solution delivery.

[0049] A second aspect of the present invention provides an apparatus for synthesizing ZN particulate polyolefin catalysts, such as... Figure 1 As shown, the synthesis equipment includes a dissolving vessel 1, a coarse filter 2, a closed centrifuge 3, and a synthesis vessel 4, which are connected in sequence and sealed together.

[0050] The dissolving vessel 1 is used to dissolve the raw materials to obtain a raw material solution;

[0051] The coarse filter 2 is used to filter the raw material solution to obtain a filtered solution;

[0052] The closed centrifuge 3 is used to centrifuge the filtered solution so that the content of insoluble solid impurities in the centrifuged solution is less than 10 mg / L.

[0053] The synthesis vessel 4 is used to synthesize ZN particulate polyolefin catalysts using the centrifuged dissolution solution.

[0054] In this invention, the dissolving vessel 1 has a stirring component and a cooling component. The stirring component is used to accelerate the dissolution and complexation of the raw materials, and the cooling component is used to cool the raw material solution, so that the solute reaction is moved away from the optimal reaction temperature, preventing the solute from reaching or exceeding the optimal reaction temperature due to impurity removal, which could lead to over-reaction and deterioration of the solution. The cooling component can be, for example, a cooling jacket.

[0055] In this invention, the coarse filter 2 can be any filtration device commonly used for filtering solutions, with a filter screen typically ranging from 60 to 200 mesh, preferably 60 to 100 mesh. From the perspective of separating metallic impurities, a magnetic coarse filter is preferred.

[0056] In this invention, the closed-loop centrifuge 3 can be any centrifuge device commonly used for centrifuging solutions. A closed-loop centrifuge is a highly efficient centrifugal separation device. Its working principle is that when material enters the closed-loop centrifuge through a pipe, a centrifugal force is applied to the liquid by high-speed rotating components inside the centrifuge. The density difference is used to achieve efficient separation of insoluble solid impurities and the liquid. After separation, the liquid is collected by the centrifugal force and then output through a pipe to subsequent equipment. Insoluble solids can be intermittently discharged or accumulated in the solid sedimentation chamber within the separation equipment and collected for periodic cleaning.

[0057] To prevent the solution from corroding the closed centrifuge and to improve airtightness, it is preferable to use a sealing ring made of fluororubber, silicone rubber or ether rubber in the closed centrifuge 3.

[0058] In this invention, the synthesis equipment also includes a liquid inlet controller 5, which is used to control the flow rate and volume of the solution introduced into the closed centrifuge, so as to ensure the centrifugal separation effect in the closed centrifuge 3.

[0059] In this invention, the dissolving vessel 1 and the coarse filter 2 are sealed together by a dissolving liquid delivery pipe 6, the coarse filter 2 and the closed centrifuge 3 are sealed together by a centrifuge inlet pipe 7, and the closed centrifuge 3 and the synthesis vessel 4 are sealed together by a synthesis vessel inlet pipe 8. Furthermore, a liquid volume controller 5 can be installed on the centrifuge inlet pipe 7.

[0060] In this invention, preferably, the filtration conditions of the coarse filter 2 are such that the content of insoluble solids in the filtered solution is less than 100 mg / L, more preferably less than 80 mg / L. Preferably, the centrifugation conditions of the closed centrifuge 3 are such that the content of insoluble solids in the centrifuged solution is less than 5 mg / L, more preferably 0 to 2 mg / L, and particularly preferably 0 mg / L. Other filtration and centrifugation conditions can be the same as those in the first aspect of this invention.

[0061] The third aspect of the present invention provides the application of the above-described method for treating the solution of ZN particulate polyolefin catalyst or the above-described synthesis apparatus for ZN particulate polyolefin catalyst in the synthesis of ZN particulate polyolefin catalyst (preferably ZN particulate polypropylene catalyst).

[0062] According to some preferred embodiments of the present invention, the solution treatment method for ZN particulate polyolefin catalysts of the present invention includes the following steps for treating the raw material solution.

[0063] Step 1: The raw materials and toluene are stirred and dissolved in a dissolving vessel to obtain a raw material solution containing solid impurities. This raw material solution can be stored in the dissolving vessel and can be sent to the coarse filter 2 through the solution delivery pipe 6.

[0064] Step 2: Use a magnetic coarse filter to initially remove larger particulate impurities and magnetically adsorbable impurities from the raw material solution to obtain a filtered solution.

[0065] Step 3: The filtered solution is continuously transported into the closed centrifuge through the centrifuge inlet pipe 7 at a stable flow rate by the inlet flow controller 5 (including flow meter and regulating valve).

[0066] Step 4: After thorough separation by a high-speed rotating closed centrifuge, the clear liquid (centrifugal dissolution liquid) free of solid impurities is discharged from the closed centrifuge through the clear liquid pipe and transported to the catalyst synthesis dissolution vessel through the synthesis vessel inlet pipe 8 for use in the subsequent preparation of polypropylene catalyst.

[0067] Step 5: Liquid impurities deposited in the closed centrifuge due to the centrifugal field caused by high-speed rotation are discharged from the closed centrifuge to the collection equipment for further processing by automatic intermittent slag discharge or manual slag removal after batch operation.

[0068] According to a more preferred embodiment of the present invention, the solution treatment method of the present invention includes the following steps.

[0069] Step 1: Solution synthesis and storage

[0070] The catalyst synthesis process involves reacting magnesium chloride, a carrier, with solid and liquid raw materials such as epichlorohydrin, tributyl phosphate, phthalic anhydride, and silicates. The resulting solution is then dissolved in toluene, forming a raw material solution containing solid impurities ranging from 0.1% to 0.5 wt% with a particle size of 0.1% to 4 μm. Toluene is the solvent, and the solute is the complex molecules formed by the reaction of the aforementioned raw materials. Insoluble solid impurities remain suspended in the solution. Under storage conditions, the synthesized and dissolved raw material solution can be cooled using indirect heat transfer to prevent the solute from reacting at or above its optimal temperature, thus avoiding over-reaction and deterioration of the solution. The raw material solution can be processed using stirred tanks or fixed-top containers for reaction, dissolution, and storage. Raw material metering, feeding, and the entire dissolution process must be carried out under high-purity nitrogen protection. The equipment must be adequately isolated from water and air, and must be fully purged with high-purity nitrogen before operation.

[0071] Step 2: Dissolving solution delivery and metering

[0072] The solution is transported from its storage container (stirred kettle or fixed-top container) to the closed-loop centrifuge via a seamless, fully enclosed pipeline and a magnetic coarse filter, using mechanical or pneumatic methods (with high-purity nitrogen as the gas source). This provides reliable transport power under controlled background pressure. A flow meter is used for metering on the transport pipeline. To precisely control the flow rate, a pneumatic regulating valve can be interlocked with the flow meter, allowing for precise control of the feed flow. Depending on the closed-loop centrifuge model, the flow control range is 500-2000 L / h. This capacity range allows for rapid removal of impurities from the solution without altering its chemical properties.

[0073] Step 3: Centrifugal separation using a closed-loop centrifuge

[0074] Closed-loop centrifuges should be fully purged and dried with high-purity nitrogen. The sealing components and rotating and lubricating parts should be inspected and maintained. Before initial use, the working chamber and accessories should be rinsed with anhydrous toluene (solvent). After nitrogen purging, the closed-loop centrifuge should be turned on and rotating at high speed before receiving the solution. Once the operating speed is reached (depending on the equipment selection, the rotation speed range is 100–10000 rpm, and the rotation speed should be adjustable), the solution should be introduced at the set flow rate. After the solution passes through the centrifuge's rotating parts at high speed, the resulting clear liquid, free of solid impurities, is discharged from the centrifuge through a guide pipe and then transported via a seamless, sealed pipeline to the catalyst synthesis unit (or clear liquid storage unit) by mechanical force, gravity, or pressure. This process can be carried out continuously or intermittently depending on the closed-loop centrifuge selection, until all the solution has been processed by the closed-loop centrifuge and then transported to the catalyst synthesis unit for subsequent reactions. Continuous operation is preferred. The space for separating and storing the solution in the equipment should be ≤10L to reduce solution loss and effectively avoid it. The solution loss in a single batch of solution processing should be less than 5% of the total solution volume. Depending on the equipment selection, if necessary, partition cooling measures can be taken to control the operating temperature below the optimal reaction temperature.

[0075] Step 4: Removal of solid residue from the closed centrifuge

[0076] Closed-loop centrifuges used for centrifugal separation employ either automatic or fixed-throughput manual unloading methods, depending on the equipment selection. Equipment using automatic unloading requires fully enclosed unloading accessories for solid sludge (slurry) collection. Methods such as solvent dilution conveying, mechanical conveying, and pneumatic conveying can be used to transport the solid sludge (slurry) between the centrifuge and the collection equipment. The solid content of the solid residue removed by automatic unloading should be ≥30% (wt%). For closed-loop centrifuges using manual unloading, after one or more batches of solution have been processed, the rotating parts should be purged with high-purity nitrogen, disassembled, and then restored to operation and adjustment through manual cleaning or replacement of rotating parts. Cleaning operations should be performed in a fume hood with exhaust gas collection and treatment facilities.

[0077] The present invention will be described in detail below through examples. In the following examples, the content of insoluble solid impurities in the solution (hereinafter also referred to as solid content) was determined by the suspended solids detector standard sample light reflectance comparison method with distilled water as standard sample. The suspended solids detector used was a G966 model manufactured by Shandong Greencare Precision Instruments Co., Ltd.

[0078] Example 1

[0079] Utilize Figure 1The synthesis equipment shown is used for processing the solution and synthesizing ZN granular polypropylene catalyst. The equipment includes a dissolving vessel 1, a solution delivery pipe 6, a coarse filter 2, a centrifuge inlet pipe 7, a closed centrifuge 3, a synthesis vessel inlet pipe 8, and a synthesis vessel 4, all connected in a sealed manner. A liquid flow controller 5 is installed on the centrifuge inlet pipe 7, which includes a flow meter and a regulating valve.

[0080] 200 kg of magnesium chloride, 100 kg of epichlorohydrin, 450 kg of tributyl phosphate, and 3500 L of toluene were added to dissolving vessel 1 and stirred to obtain a Zn granular polypropylene catalyst feedstock solution (total volume approximately 4000 L, insoluble solid impurity content 2 wt%, insoluble solid diameter 0.1–4 μm, solid density 5.8 g / cm³). 3 ).

[0081] The Zn granular polypropylene catalyst feedstock solution was fed into a 60-mesh magnetic coarse filter (coarse filter 2) at a pressure of 0.1 MPa (G) using high-purity nitrogen as a pressure source to obtain a filtered solution. Five samples were randomly taken from the filtered solution, and their solid content was measured to be in the range of 51–57 mg / L.

[0082] Then, under the control of the influent controller 5, the filtered solution was introduced into the closed centrifuge 3 with automatic intermittent slag discharge at a rate of 1500 L / hr, and continuously centrifuged at 6500 rpm. After centrifugation, no visible solid impurities were found in the centrifuged solution, and its solid content was measured to be 0 mg / L. The total processing time was less than 3 hours, and a total of 4 kg of impurities were separated from this batch of solution, which was a thick solid-liquid mixture.

[0083] Example 2

[0084] The granular polypropylene catalyst feedstock solution was treated according to the method in Example 1, with the only difference being the processing flow rate of the centrifugal separation, as shown in Table 1. The solid content values ​​of the clear liquid obtained from centrifugation, i.e., the centrifuged solution, are shown in Table 1.

[0085] Table 1

[0086] Flow rate (L / hr) Solid content (mg / L) 500 0 1100 0 1270 0 1550 0 1710 0 1820 2 2010 6 2230 14 2390 27 2510 32

[0087] Example 3

[0088] The granular polypropylene catalyst feedstock solution was treated according to the method in Example 1, with the only difference being that the centrifugal separation flow rate was 2000 L / hr, and the rotation speed was as shown in Table 2. The solid content values ​​of the clear liquid obtained from centrifugation, i.e., the centrifuged solution, are shown in Table 2.

[0089] Table 2

[0090] Rotational speed (rpm) Solid content (mg / L) 1500 51 2000 37 2500 28 3000 21 3500 17 4000 13 4500 11 5000 9 5500 8 6000 7 6500 6 7000 4 7500 2 8000 0

[0091] Comparative Example 1

[0092] The granular polypropylene catalyst solution, identical to that in Example 1, was subjected to two-stage filtration (first stage: a 60-mesh magnetic coarse filter; second stage: a four-layer stacked 400-mesh metal wire mesh filter). High-purity nitrogen was used as the pressure source for filtration, with a pressure difference of 0.2 MPa(G). After separation, visible solid impurities remained in the solution. During the process, the filter cake became too thick, causing blockages and flow interruptions multiple times. The filter cake was replaced by intermittent high-purity nitrogen backflushing to maintain filtration. The total processing time was 13 hours and 18 minutes, and the solid content of the filtered solution was measured to be 19 mg / L.

[0093] The results above show that the method of the present invention removes solid insoluble impurities more thoroughly and efficiently than the filtration method of Comparative Example 1, with less loss of solution. In Comparative Example 1, the main factors contributing to solution loss were residues in the filter chamber and pipes, while in Example 1, the main factor contributing to solution loss was slurry entrainment during intermittent slag discharge.

[0094] Zn-containing particulate polyolefin catalysts were synthesized using the centrifuged solutions obtained in Examples 1-3 and the filtered solutions obtained in Comparative Example 1. Specifically, phthalic anhydride was added to the filtered solutions, and after complete dissolution, the system temperature was lowered to below -25°C. Titanium tetrachloride was slowly added dropwise, and then the system was gradually and uniformly heated to 80°C. Diisobutyl phthalate was added, and the temperature was maintained at 80°C for 1 hour. The catalyst gradually precipitated from the solution and gradually increased in size. Then, titanium tetrachloride was added and reacted for 1 hour. The mixture was washed three times with hexane and dried under vacuum to obtain a grayish-yellow solid powder catalyst.

[0095] The proportion of large particles in the catalysts prepared above that did not meet the usage requirements was determined. The final catalyst obtained using the filtrate of Comparative Example 1 was approximately 2 kg / B, while the catalyst obtained using the filtrate of Examples 1 and 2 with a flow rate of 500–1710 L / hr and the filtrate of Example 3 with a rotation speed of 8000 rpm was approximately 1 kg / B. The catalyst obtained using the filtrate of Examples 2 with flow rates of 1820 and 2010 L / hr and the filtrate of Example 3 with a rotation speed of 5000–7500 rpm was approximately 1.1 kg / B. The catalyst obtained using the filtrate of Example 2 with a flow rate of 2230 L / hr… The catalyst obtained using the filtration solution with a flow rate of 3500-4500 rpm in Example 2 and Example 3 with a flow rate of 2390 L / hr, the catalyst obtained using the filtration solution with a flow rate of 2500-3000 rpm in Example 2, the catalyst obtained using the filtration solution with a flow rate of 2510 L / hr in Example 2 and Example 3 with a flow rate of 2000 rpm, the catalyst obtained using the filtration solution with a flow rate of 1500 rpm in Example 3, and the catalyst obtained using the filtration solution with a flow rate of 1500 rpm in Example 3, is approximately 1.2 kg / B.

[0096] Furthermore, the catalyst obtained from the centrifuged dissolution of Final Example 1 contains fewer inactive and low-activity particles, and the particles are uniform with virtually no large particles. This helps prevent the catalyst from clogging the device during use, and simplifies the synthesis process, reduces operational intensity, and improves stability. In contrast, the catalyst obtained from the centrifuged dissolution of Comparative Example 1 contains larger particles and more inactive and low-activity particles, increasing the probability of device clogging during use. Moreover, in the centrifuged dissolutions of Examples 2 and 3, by controlling the solid content to below 10 mg / L (preferably below 5 mg / L, more preferably 0–2 mg / L, and particularly preferably 0 mg / L), the resulting catalyst is more uniform, free from abnormal morphology, non-catalyst aggregates, and catalyst particle agglomeration, and further improves the polymerization catalytic performance and industrial application performance (such as transport performance) of the catalyst.

[0097] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating the solution of Zn particulate polyolefin catalysts, characterized in that, The solution treatment method is performed using synthetic equipment. The synthesis equipment includes a dissolving vessel (1), a coarse filter (2), a closed centrifuge (3), and a synthesis vessel (4) connected in sequence and sealed. The dissolving vessel (1) is used to dissolve the raw materials to obtain a raw material solution; The coarse filter (2) is used to filter the raw material solution to obtain a filtered solution; The closed centrifuge (3) is used to centrifuge the filtered solution; The synthesis vessel (4) is used to synthesize ZN particulate polyolefin catalysts using the centrifuged dissolution solution. The solution treatment method includes: under closed conditions, filtering and centrifuging the raw material solution in sequence, so that the content of insoluble solid impurities in the centrifuged solution is less than 10 mg / L, and then using the centrifuged solution for the synthesis of ZN particulate polyolefin catalyst. The raw material solution is a toluene solution containing magnesium chloride. The content of insoluble solid impurities in the filtered solution obtained by filtration is less than 100 mg / L. The centrifuge speed is above 5000 rpm, and the centrifuge flow rate is below 2000 L / hr.

2. The solution treatment method according to claim 1, wherein, The content of insoluble solid impurities in the centrifuged solution obtained by centrifugation is less than 5 mg / L.

3. The solution treatment method according to claim 2, wherein, The content of insoluble solid impurities in the centrifuged solution obtained by centrifugation is 0~2 mg / L.

4. The solution treatment method according to claim 1, wherein, The filter used in the filtration process has a mesh size of 60-200.

5. The solution treatment method according to claim 1, wherein, The filtration is performed using a magnetic coarse filter.

6. The solution treatment method according to claim 1, wherein, The centrifuge operates at a speed of 6000 rpm or higher, and the centrifuge has a processing flow rate of 1000~1500 L / hr.

7. The solution treatment method according to claim 1, wherein, The concentration of magnesium chloride in the raw material solution is 3~10wt%.

8. The solution treatment method according to claim 7, wherein, The concentration of magnesium chloride in the raw material solution is 4-7 wt%.

9. The solution treatment method according to claim 7, wherein, The raw material solution also contains one or more additives selected from epoxy compounds, ester compounds, acid anhydride compounds, alcohol compounds, and silicate ester compounds.

10. The solution treatment method according to claim 1, wherein, The closed centrifuge (3) uses a sealing ring made of fluororubber, silicone rubber or ether rubber.

11. The solution treatment method according to claim 1, wherein, The closed centrifuge (3) ensures that the content of insoluble solid impurities in the centrifuged solution is below 5 mg / L.

12. The solution treatment method according to claim 11, wherein, The closed centrifuge (3) ensures that the content of insoluble solid impurities in the centrifuged solution is 0~2 mg / L.

13. The application of the solution treatment method for ZN particulate polyolefin catalyst according to any one of claims 1-12 in the synthesis of ZN particulate polyolefin catalyst.

14. The application of the solution treatment method for ZN particulate polyolefin catalysts according to any one of claims 1-12 in the synthesis of ZN particulate polypropylene catalysts.

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