Continuous separation method of rare earth-based catalyst suspension for polymerization

Abstract

The invention relates to the field of chemical production and material processing separation, and discloses a continuous separation method of a rare earth-based catalyst suspension for polymerization. The present invention relates to a method for preparing a rare earth-based catalyst for polymerization, the method comprising: mixing a suspension of the rare earth-based catalyst for polymerization with a conditioning solvent, and centrifuging the resulting mixture in an apparatus comprising at least two stages of filtration units to separate catalysts having different particle sizes. According to the method, cascade separation of catalysts with different particle sizes in the suspension can be efficiently realized, whole-process treatment can be performed in integrated equipment, operation is continuous, the treatment efficiency is high, the equipment investment is low, and the field can be saved.

Description

Technical Field

[0001] The invention relates to the field of chemical production and material processing separation, and in particular to a continuous separation method of a rare earth-based catalyst suspension for polymerization. Background Art

[0002] During the catalyst preparation and production process, some catalysts are generated by reaction and exist in the reaction liquid in the form of solid suspension. The catalyst particles in the suspension reach the micron level, and the density is close to that of the reaction liquid. It is difficult to separate them efficiently and at a high recovery rate, and the product loss during the separation process is large. Therefore, it usually involves the separation and purification process of solid materials in the suspension to obtain high-purity and high-quality catalyst products. The suspension separation and purification process usually involves washing and separation in steps by centrifuge or filter press. The solid phase in the suspension is separated by centrifuge or filter press after static stratification, and then the flushing solution is added for stirring, the solid material is washed, and then separated by centrifuge or filter press, and multiple intermittent operations are performed until the product meets the index requirements. Traditional intermittent filter press or centrifugation has more manual operations, frequent switching between processes, and a long process time. It is necessary to switch continuously in the processes of washing, static stratification, filtration / centrifugation, and material transfer until the separation and purification is completed.

[0003] In addition, the particle size distribution range of the solid phase particles of the catalyst suspension is relatively wide, and some of the ultra-fine catalyst particles still need to be further separated after being collected together with the conventional size catalyst particles, and the ultra-fine catalyst particles need to be post-processed. At the same time, the composition of the catalyst suspension is complex, and some catalysts form foams on the surface of the reaction liquid, and the state is stable. It is not easy to flocculate and stratify during centrifugation or filter pressing separation. In the existing suspension technology that uses a centrifuge for "filtration, washing and separation", it is not good to selectively separate the catalyst particles within a certain size range, and the ultra-fine particle catalyst is not easy to post-process, resulting in a reduction in effective separation capacity. In addition, if the demand for suspension treatment is large, the number of centrifuges and supporting equipment required is large, the corresponding equipment investment increases, the loss is also large, and the economy of the recovery process is reduced. In the existing filter pressing separation and purification suspension technology, although the catalyst solid phase particles with large particle size differences can be selectively distinguished by filter pressing aperture control, the physical property difference between the solid phase and the solvent phase of the catalyst suspension is small, the suspension state is stable, the flocculation process is slow, and it is not easy to stratify. In the filter pressing process, it takes a long time to work, and inevitably causes a large loss of catalyst materials.

[0004] Existing centrifugal filtration or filter press separation suspension technology are intermittent operations, with a large number of equipment and supporting facilities, a large footprint, and the separation of materials requires power supply to achieve frequent transfer between different operation sections, and the completion of the entire process for efficient separation requires smooth human operation. At the same time, the automation level is low, and it cannot meet the needs of large-scale and large-capacity chemical continuous automation production processes. Therefore, it is also necessary to develop a solution that can better separate the catalyst in the treatment of the catalyst suspension, realize the convenient separation and recovery of the catalyst particles that can be directly reused, and realize the continuity of the operation, improve the processing efficiency, shorten the process and operation, reduce the process time and power supply, and save equipment investment and operation section site occupation. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a continuous separation method for a rare earth-based catalyst suspension for polymerization, which can efficiently realize the step-by-step separation of catalysts of different particle sizes in the suspension and can carry out full-process processing in an integrated device, with continuous operation, high processing efficiency, low equipment investment, and space saving.

[0006] In order to achieve the above object, the present invention provides a continuous separation method of a rare earth-based catalyst suspension for polymerization, the method comprising: mixing the rare earth-based catalyst suspension for polymerization with a regulating solvent, and centrifuging the obtained mixture, wherein the centrifugation is performed in a device comprising at least two stages of filtering units to separate catalysts with different particle sizes;

[0007] Wherein, the regulating solvent is selected from at least one of C2-C8 alcohols, alcohol polymers and C4-C8 ethers.

[0008] Through the above technical scheme, in the treatment of rare earth-based catalyst suspension for polymerization, the catalyst can be better separated, and the catalyst particles that can be directly reused can be conveniently separated and recovered; and the operation can be continuous, the processing efficiency can be improved, the number of equipment required is small, and the catalyst can be separated in stages in one device, shortening the process flow and operation, reducing the process time and power supply, and saving equipment investment and operation section site occupancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The invention provides a device for implementing the method of the invention.

[0010] Description of Reference Numerals

[0011] 1-flocculation unit; 2-third-stage filtration unit; 3-fourth-stage filtration unit; 4-liquid collection unit; 5-feeding port for material to be processed; 6-motor; 7-universal spray pipe; 8-gas feeding component; 9-liquid discharge pipe; 10-backflush gas outlet; 11-first-stage filtration unit; 12-second-stage filtration unit; 13-motor; 14-sealing ring; 15-sealing ring. DETAILED DESCRIPTION

[0012] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0013] The present invention provides a continuous separation method of a rare earth-based catalyst suspension for polymerization, the method comprising: mixing the rare earth-based catalyst suspension for polymerization with a regulating solvent, and centrifuging the obtained mixture, wherein the centrifugation is performed in a device comprising at least two stages of filtering units to separate catalysts with different particle sizes;

[0014] Wherein, the regulating solvent is selected from at least one of C2-C8 alcohols, alcohol polymers and C4-C8 ethers.

[0015] Rare earth-based catalyst suspension for polymerization, wherein the solid phase particles are often unevenly distributed in size, and contain catalyst particles of small size that cannot be directly reused; and, such a suspension state is generally more stable, and conventional centrifugation or filter pressing cannot cause the suspension to flocculate and stratify, so the effective separation efficiency is very low, the recovery rate of the catalyst is poor, and the purity of the recovery is also low. Small-sized catalyst particles tend to adhere to catalyst solids with larger particle sizes (such as blocks), which will make the catalyst of large particle size not conducive to direct recycling due to purity and other reasons. However, the inventors of the present invention have found in their research that when the rare earth-based catalyst suspension for polymerization is mixed with the above-mentioned regulating solvent, in the presence of the regulating solvent, the physical properties of the rare earth-based catalyst suspension for polymerization are changed, and the spatial distribution of the catalyst particles is also affected, and the catalyst can be better separated from the solvent in the suspension with the centrifugal operation. Among them, at least two stages of filtration units are used, and the second stage filtration unit is arranged on the outside of the first stage filtration unit. The first stage filtration unit and the second stage filtration unit can have different filtration particle sizes. The filtration particle size of the first stage filtration unit can be slightly larger to achieve the interception of large-size (such as block-shaped) catalyst particles. The filtration particle size of the second stage filtration unit can be set so that the particles intercepted by the second stage filtration unit can be directly reused, so that the catalyst particles with suitable particle size and can be directly recycled can be directly recovered (this part of the particle size is smaller than the block catalyst as mentioned above, but larger than the small-size catalyst particles that cannot be directly recovered, the particle size is suitable, and often there is no obvious attachment of small-size catalyst particles that cannot be directly recovered, so it can be directly recycled. The particle size of this part is generally 2-200μm).

[0016] The method of the present invention can avoid intermittent operation in traditional methods, and can carry out full-process processing in an integrated device, continuously and efficiently realizing the step-by-step separation of catalysts of different particle sizes in the suspension, with continuous operation, higher efficiency, and also saving equipment space.

[0017] According to the present invention, preferably, the C2-C8 alcohol is selected from C2-C6 polyols and / or monools.

[0018] According to the present invention, preferably, the C4-C8 ether is selected from C4-C8 monoether.

[0019] According to the present invention, preferably, the weight average molecular weight of the alcohol polymer is 200-2000 (for example, it can be 200, 500, 800, 1000, 1200, 1500, 1800, 2000 and ranges formed by any two of the above values ​​and values ​​within the range) g / mol.

[0020] Preferably, the regulating solvent is selected from at least one of ethylene glycol, propylene glycol, glycerol, cyclohexanol, ethyl ether, propyl ether, butyl ether and polyethylene glycol having a weight average molecular weight of 400-800 g / mol;

[0021] The inventors of the present invention have particularly found in their research that the use of the above-mentioned regulating solvent can better change the physical properties of the rare earth-based catalyst suspension for polymerization, further accelerate the flocculation and stratification process, and better achieve the separation of the catalyst and the solvent in the suspension.

[0022] According to the present invention, preferably, the volume ratio of the rare earth-based catalyst suspension for polymerization to the regulating solvent is 1:(0.05-1), more preferably 1:(0.1-0.3). This can further effectively achieve the separation of the catalyst from the solvent in the suspension.

[0023] According to the present invention, preferably, the solvent in the rare earth-based catalyst suspension for polymerization is selected from at least one of water, ethanol and propanol. The inventors of the present invention further found in the study that when the solvent in the rare earth-based catalyst suspension for polymerization is water, the various specific adjustment solvents as described above can all achieve better results. When the solvent in the rare earth-based catalyst suspension for polymerization is ethanol or propanol, polyethylene glycol can be selected to ensure better results.

[0024] Preferably, the density of the rare earth-based catalyst suspension for polymerization is 0.7-1.5 g / cm 3 , preferably 0.8-1.1 (for example, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1 and the range formed by any two of the above values ​​and the value within the range) g / cm 3 .

[0025] Preferably, in the rare earth-based catalyst suspension for polymerization, the mass concentration of the catalyst is 0.01-20wt%, preferably 0.1-10 (for example, it can be 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and the range formed by any two of the above values ​​and the values ​​within the range) wt%.

[0026] Preferably, in the rare earth-based catalyst suspension for polymerization, the particle size of the catalyst is 0.05-1000 μm, preferably 0.1-200 μm.

[0027] Generally, the viscosity of the rare earth-based catalyst suspension for polymerization may be 10-200 mPa·s, particularly 50-120 mPa·s.

[0028] The method provided by the present invention is particularly suitable for a rare earth-based catalyst suspension for polymerization having the properties as described above, in particular a rare earth-based catalyst suspension for emulsion polymerization.

[0029] It can be understood that, generally, a rare earth-based catalyst is composed of a carrier and rare earth.

[0030] According to a particularly preferred embodiment of the present invention, the rare earth element in the rare earth-based catalyst suspension for polymerization is selected from at least one of yttrium, scandium, zirconium, lanthanum, cerium, praseodymium and neodymium.

[0031] Preferably, the carrier of the rare earth-based catalyst is at least one of silicon dioxide, aluminum oxide, activated carbon and titanium oxide. Such a rare earth-based catalyst suspension for polymerization generally meets the properties as described above.

[0032] According to the present invention, preferably, the mixing and centrifugation are independently carried out at a temperature of 20-100°C (for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, and the range formed by any two of the above values ​​and the value within the range). When the solvent in the rare earth-based catalyst suspension for polymerization is water, the mixing and centrifugation are independently carried out at 20-100°C. When the solvent in the rare earth-based catalyst suspension for polymerization is ethanol or propanol, the mixing and centrifugation can be independently carried out at a temperature of 50-70°C (for example, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, and the range formed by any two of the above values ​​and the value within the range). The rare earth-based catalyst suspension for polymerization and the regulating solvent can be heated to the above temperature before being fed into the equipment. In general industrial equipment, due to continuous operation, the temperature of the material will not change significantly during the separation process, and can generally be maintained at about the heated temperature.

[0033] In the method provided by the present invention, mixing and centrifugation can be performed simultaneously to achieve continuous separation, that is, the rare earth-based catalyst suspension for polymerization and the regulating solvent can be simultaneously delivered to the device, and during the centrifugation process, the materials will be mixed at the same time.

[0034] Generally, the particle size that can be reused is 2-200 μm. The specific filtration particle size of the first-stage filtration unit and the second-stage filtration unit can be specifically set according to the rare earth-based catalyst suspension for polymerization. The filtration particle size of the first-stage filtration unit can generally be 100-200 μm, and the large particles retained and the very fine particles attached thereto can also be easily washed away.

[0035] It can be understood that the filter particle size refers to the maximum particle size of particles that can pass through a certain filter unit.

[0036] According to the present invention, preferably, the filtration particle size of the second stage filter unit is such that the particles retained by the second stage filter unit can be directly reused. Generally, the filtration particle size of the second stage filter unit can be 2-200 μm, especially 2-80 (for example, it can be 2, 2.5, 3, 5, 8, 10, 20, 30, 40, 50, 60, 70, 80 and the range formed by any two of the above values ​​and the value within the range) μm.

[0037] According to a particularly preferred embodiment of the present invention, the filtration particle size of the first-stage filter unit is greater than the filtration particle size of the second-stage filter unit.

[0038] The first-stage filter unit and the second-stage filter unit can adopt filter cloth, filter screen, filter membrane, filter plate or other materials with porous structure. Wherein, the second-stage filter unit can adopt a filter membrane prepared by a polymer material with chemical adsorption function, for example, it can be polynylon 66, polyethersulfone, polypropylene, polytetrafluoroethylene or polyvinylidene fluoride material, or it can adopt a functionalized polymer filter membrane loaded with polysulfonic acid compounds obtained by sulfonation modification of the above-mentioned polymer material, and the loading amount of the polysulfonic acid compounds can be 0.1-10wt% of the total weight of the membrane. For example, a polyethersulfone membrane loaded with polyvinyl sulfonic acid-maleic acid (polyvinyl sulfonic acid and maleic acid polymerization molar ratio is 1:1) can be adopted, and the filtration particle size is 2μm, and it has chemical adsorption performance at the same time.

[0039] As mentioned above, catalyst solids with slightly larger particle sizes may be attached with catalyst particles with smaller particle sizes that cannot be directly recycled. Therefore, the catalyst solids with the above-mentioned large particle sizes can be intercepted by the first-stage filter unit by controlling the filtration particle size of the first-stage filter unit, and the catalyst particles with suitable particle sizes that can be directly recycled can be intercepted by the second-stage filter unit by controlling the filtration particle size of the second-stage filter unit. The catalyst particles with too small particle sizes that cannot be directly recycled will pass through the above-mentioned two-stage filter units to complete the separation. In this way, step separation of different particle sizes is achieved, and the catalyst particles that can be directly recycled can be recovered more conveniently. In addition, the filtration particle size of the first-stage filter unit is slightly larger, so the solvent and the regulating solvent of the suspension itself can also pass through, and the water content in the material of the filter unit can be higher, and the material volume is larger, and the catalyst with too large particle size has been intercepted by the first-stage filter unit, so that the solid siltation and blockage in the subsequent separation unit can also be reduced.

[0040] According to the present invention, preferably, the centrifugal speeds of the first-stage filter unit and the second-stage filter unit are independently 50-300 rpm, preferably 80-150 (for example, it can be 80, 90, 100, 110, 120, 130, 140, 150 and the range formed by any two of the above values ​​and the value within the range) rpm. The inventors of the present invention also found that under the above centrifugal speed, the solvent can be better coordinated and the step separation of catalyst particles can be achieved more efficiently. Among them, the same or different motors can be used to control the centrifugal direction and speed of the first-stage filter unit and the second-stage filter unit respectively.

[0041] Preferably, the centrifugation time is 60-600 s, preferably 200-400 (for example, it can be 200, 210, 220, 230, 240, 250, 280, 300, 320, 340, 350, 380, 400 and the range formed by any two of the above values ​​and the values ​​within the range) s.

[0042] According to the present invention, preferably, the device further comprises a third-stage filter unit. The third-stage filter unit is arranged outside the second-stage filter unit. The inventor of the present invention further found in the study that the presence of the third-stage filter unit and the rotation during centrifugation can further promote the separation of the solids on the first-stage filter unit and the second-stage filter unit and the liquid phase carrying unusable ultrafine particles.

[0043] Preferably, the device further comprises a fourth filter unit. The fourth filter unit is arranged outside the third filter unit, so as to further promote the separation of the solids on the first and second filter units and the liquid phase carrying unusable ultrafine particles.

[0044] It can be understood that the third-stage filter unit and the fourth-stage filter unit are mainly used to promote the separation between the first-stage filter unit and the second-stage filter unit, and are not particularly provided for intercepting solid particles. Therefore, the third-stage filter unit and the fourth-stage filter unit can be made of stainless steel or other rigid large-pore materials. For example, the filtration particle size of the third-stage filter unit and the fourth-stage filter unit can be 200-5000 μm, especially 1000-3000 μm.

[0045] The filter units at each stage can be assembled in a detachable manner.

[0046] The same or different motors may be used to control the centrifugal direction and speed of the third-stage filter unit and the fourth-stage filter unit respectively.

[0047] According to the present invention, preferably, the centrifugal speeds of the third-stage filter unit and the fourth-stage filter unit are each independently 800-10000 rpm, preferably 1000-5000 (for example, it can be 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000 and the range formed by any two of the above values ​​and the values ​​within the range) rpm.

[0048] After the above four-stage filtration unit, most of the liquid (which contains the suspension's own solvent, the regulating solvent, and the catalyst with too small particles) will pass through the fourth-stage separation unit. This part of the material can be collected and then passed through a solvent recovery device (such as a distillation condensation-filtration device) to recover the suspension's own solvent and the regulating solvent.

[0049] According to the present invention, preferably, the method further comprises: during the centrifugation process, spraying an eluent onto the material retained by the first-stage filter unit. The material retained by the first-stage filter unit may be attached to and / or coated with catalyst particles that are too small to be directly recovered. By spraying the eluent, this part of the material can be washed off, thereby improving the purity of the material retained by the first-stage filter unit, so that it can be recycled after elution. In addition, as for the catalyst retained by the second-stage filter unit, as mentioned above, this part generally will not be obviously attached with catalyst particles of small particle size that cannot be directly recovered. If there are any, they can also be fully washed off by the eluent.

[0050] The eluent may be a regulating solvent or the solvent of the suspension itself recovered by the above-mentioned solvent recovery device. The spraying of the eluent may be started later after the start of centrifugation, such as starting the spraying 8-20 seconds after the start of centrifugation. In order to further ensure the elution effect, a universal spray pipe may be provided in the center of the equipment to ensure that all parts on the first-stage filter unit are covered as much as possible. The stop time of the spraying may be determined by analyzing the content of the catalyst mixed in the liquid passing through the fourth-stage filter unit. When the catalyst content is still high, it means that the catalyst particles that are too small have not been fully separated, and the eluent may continue to be sprayed.

[0051] According to the present invention, preferably, the method further comprises: after the centrifugation is completed, gas is blown into the device against the direction of the filtered material to purge and / or dry the material attached to each level of the filter unit. The purge can be stopped after the material is fully dried, for example, the purge time can be 60-120s, and then the product is collected. Taking the above-mentioned situation containing a four-stage filter unit as an example, gas is blown into the device against the direction of the filtered material, that is, the direction of the gas is from the fourth-stage filter unit to the first-stage filter unit. The gas is preferably a slightly positive pressure hot gas, for example, a gas with a pressure of 0.01-0.02MPa and a temperature of 100-350°C. It can be understood that the selected gas should not react with the catalyst, and can generally be nitrogen, air, etc. After purging, the material intercepted by the first-stage filter unit and the second-stage filter unit is dried, which is conducive to recovery. It can be understood that gas can be blown in again after the spraying of the eluent is completed to purge and / or dry. After such in-situ drying, the recovery of the catalyst can be achieved in the integrated device. A gas outlet pipe may be provided in the device to lead the purged gas out of the device.

[0052] According to the present invention, preferably, the centrifugal directions of the first-stage filter unit and the second-stage filter unit are the same, the centrifugal directions of the third-stage filter unit and the fourth-stage filter unit are the same, and the centrifugal directions of the first-stage filter unit and the centrifugal directions of the third-stage filter unit are the same or opposite, preferably opposite. During centrifugation, the above four-stage filter units all rotate.

[0053] The first-stage filter unit and the second-stage filter unit can be controlled by the same motor (so that the rotation speeds of the two are the same), and the third-stage filter unit and the fourth-stage filter unit can be controlled by another motor (the rotation speeds are also the same).

[0054] Furthermore, as described above, preferably, the third-stage filter unit and the fourth-stage filter unit have the same centrifugal direction, and the centrifugal speed is 800-10000rpm (more preferably 1000-5000rpm); the first-stage filter unit and the second-stage filter unit have the same centrifugal direction, and the centrifugal speed is 50-300rpm (more preferably 80-150rpm). The first-stage filter unit and the third-stage filter unit preferably have different centrifugal speeds, and the directions are preferably opposite, which can be called differential reverse centrifugation. The inventors of the present invention have found that such a differential reverse centrifugation method can further improve the separation efficiency.

[0055] Among them, the inventor of the present invention has found in particular that, for the rare earth-based catalyst suspension for polymerization, combined with the differential reverse centrifugation in the above-mentioned four-stage filter unit, as well as the physical pore size control and chemical adsorption of the second-stage filter unit material, a high-purity catalyst product can be obtained with high throughput. In particular, when the solvent in the rare earth-based catalyst suspension for polymerization is water, the rare earth-based catalyst suspension for polymerization and the alcohol adjustment solvent (which can be ethylene glycol or propylene glycol) are heated to 60-100°C, and then the suspension and the adjustment solvent are sent to the separation device at a volume ratio of 1: (0.1-0.3). The first-stage filter unit and the second-stage filter unit rotate in the same direction and at the same speed, and the centrifugal speed is 100-150rpm; the third-stage filter unit and the fourth-stage filter unit rotate in the same direction and at the same speed, and the centrifugal speed is 1000-2000rpm; the first-stage filter unit and the third-stage filter unit rotate in opposite directions. The filtration particle size of the first filter unit can be 100-110 μm, the filtration particle size of the second filter unit can be 2-10 μm, and the filtration particle size of the third and fourth filter units can be 1000-1500 μm. After the centrifugation is turned on for 10-15 seconds, the eluent is sprayed. The centrifugation can last for 200-300 seconds.

[0056] After the above description, those skilled in the art can understand the operation mode of the present invention and can organize the equipment accordingly to implement the above operation. For example, the operation provided by the present invention can be performed in the following manner: Figure 1 In the device shown, 1 is a flocculation unit, 2 is a third-stage filtration unit, 3 is a fourth-stage filtration unit, 4 is a liquid collection unit, 5 is a feed port for the material to be treated, 6 and 13 are motors, 7 is a universal spray pipe, 8 is a gas feed component, 9 is a liquid discharge pipe; 10 is a back-blowing gas outlet; 11 is a first-stage filtration unit; 12 is a second-stage filtration unit, and 14 and 15 are sealing rings. The rare earth-based catalyst suspension for polymerization and the adjustment solvent enter the flocculation unit 1 from the feed port 5 for the material to be treated, and flocculation occurs therein. The motor 6 drives the first-stage filtration unit and the second-stage filtration unit to rotate in the same direction and at the same speed, and the motor 13 drives the third-stage filtration unit and the fourth-stage filtration unit to rotate in the same direction and at the same speed. The separated liquid enters the liquid collection unit 4 and leaves the device from the liquid discharge pipe 9. The universal spray pipe 7 can make the sprayed liquid cover all places on the first-stage filtration unit. From the wall surface of the gas feed component 8, gas can be purged to all places inside the device against the direction of the filtered material. The gas entering the interior of the device can leave the device from the backwash gas outlet 10 .

[0057] The present invention will be described in detail below by way of examples. Unless otherwise specified, in the following examples and comparative examples, Figure 1 is carried out in the device shown.

[0058] The recovery rate is the ratio of the mass of the recovered catalyst to (the total volume of the added suspension × the mass concentration of the catalyst). The purity is the mass proportion of the recovered catalyst with a particle size greater than 2 μm.

[0059] Example 1

[0060] Rare earth-based catalyst suspension A for polymerization, wherein the solvent is water and the density is 1.05 g / cm 3 The mass concentration of the catalyst is 10wt%, wherein the catalyst particle size distribution is 0.1-100μm, and the catalyst is a neodymium-based material with an Al2O3-SiO2 carrier.

[0061] The rare earth-based catalyst suspension for polymerization and the regulating solvent are first heated to 100° C. and then sent to the separation device.

[0062] Turn on the two motors, the first-stage filter unit and the second-stage filter unit rotate in the same direction and speed (100 rpm), the third-stage filter unit and the fourth-stage filter unit rotate in the same direction and speed (1000 rpm), and the first-stage filter unit and the third-stage filter unit rotate in opposite directions.

[0063] The material of the first-stage filter unit is filter cloth, and the filtration particle size is 100μm.

[0064] The material of the second-stage filtration unit is polyethersulfone filter membrane with a filtration particle size of 2μm.

[0065] The third-stage filter unit and the fourth-stage filter unit are made of stainless steel, and the filtration particle size is 1000μm.

[0066] The polymer suspension and the ethylene glycol adjustment solvent enter the device from the feed port 5 of the material to be treated at a feed volume ratio of 1:0.1. The larger catalyst particles are intercepted on the first-stage filter unit 11, and the second-stage filter unit 12 intercepts the catalyst particles with the smaller particle size.

[0067] After the centrifuge is turned on for 10 seconds, deionized water starts to be sprayed from the universal spray pipe 7 and is evenly sprayed to various locations of the first-stage filter unit 11 .

[0068] The liquid collecting unit 4 continuously collects liquid, and the catalyst content in the liquid is continuously monitored. The collected liquid is sent to the distillation condensation-filtration device to recover the deionized water and the adjustment solvent therein respectively. The deionized water is used as the eluent and sent to the device again.

[0069] When the catalyst content of the discharged liquid from the liquid discharge pipe 9 is less than 100 ppm after online analysis, it is considered that the elution of the material intercepted by the first-stage filtration unit 11 has been sufficient, and the spraying of the eluent is stopped at this time. The centrifugal process lasts for 200 seconds. Then, nitrogen gas with a pressure of 0.01 MPa and a temperature of 200° C. is blown into the device in reverse through the gas feeding component 8 for 100 seconds.

[0070] Solid materials attached to the first-stage filter unit and the second-stage filter unit are collected to obtain reusable catalyst particle products (>2 μm) with a purity of 99% and a catalyst recovery rate of 99%.

[0071] Example 2

[0072] The method of Example 1 is followed, except that the material of the second stage filtration unit is replaced with a modified functionalized polyethersulfone filter membrane, that is, the polyethersulfone filter membrane is loaded with 10 wt % of polyvinylsulfonic acid-maleic acid relative to the total weight of the membrane, and the filtration particle size is 2 μm.

[0073] The obtained catalyst particles are reusable (>2 μm) with a purity of 99.8% and a catalyst recovery rate of 99%.

[0074] Example 3

[0075] The method of Example 1 was followed, except that the adjustment solvent was replaced with glycerol.

[0076] The obtained catalyst particles are reusable (>2 μm) with a purity of 99.4% and a catalyst recovery rate of 99 wt%.

[0077] Example 4

[0078] The method of Example 1 is different from that of Example 1:

[0079] The rare earth-based catalyst suspension A for polymerization was replaced with rare earth-based catalyst suspension B for polymerization, wherein the solvent was ethanol and the density was 0.817 g / cm 3 The mass concentration of the catalyst is 0.5wt%, wherein the catalyst particle size distribution is between 0.2-200μm, and the catalyst is a scandium-based material with an Al2O3 carrier. The material of the second-stage filter unit is replaced with a polyvinylidene fluoride filter membrane, and the filtration particle size is 3μm.

[0080] The rare earth-based catalyst suspension for polymerization and the regulating solvent are first heated to 70° C. and then sent to the separation device.

[0081] The regulating solvent was polyethylene glycol 400, and the feed volume ratio of the polymer suspension to the regulating solvent was 1:0.2.

[0082] The centrifugal speed of the first and second filter units is 100 rpm, and the centrifugal speed of the third and fourth filter units is 1000 rpm, with opposite directions. The centrifugal process lasts for 250 seconds.

[0083] The obtained catalyst particles are reusable (>2 μm) with a purity of 99.2% and a catalyst recovery rate of 98%.

[0084] Example 5

[0085] The method of Example 1 is different from that of Example 1:

[0086] The rare earth-based catalyst suspension A for polymerization was replaced with rare earth-based catalyst suspension C for polymerization, wherein the solvent was water and the density was 0.988 g / cm 3 The mass concentration of the catalyst is 10wt%, wherein the catalyst particle size distribution is between 1-100μm, and the catalyst is a yttrium-based material with a SiO2 carrier. The material of the second-stage filter unit is replaced with a polynylon 66 filter membrane, and the filtration particle size is 10μm.

[0087] The rare earth-based catalyst suspension for polymerization and the regulating solvent are first heated to 60° C. and then sent to the separation device.

[0088] The regulating solvent is propylene glycol, and the feed volume ratio of the polymer suspension to the regulating solvent is 1:0.3.

[0089] The centrifugal speed of the first-stage filter unit and the second-stage filter unit is 150 rpm, the centrifugal speed of the third-stage filter unit and the fourth-stage filter unit is 2000 rpm, and the rotation directions of the first-stage filter unit and the third-stage filter unit are opposite.

[0090] The obtained catalyst particles are reusable (>2 μm) with a purity of 99.5% and a catalyst recovery rate of 98.3%.

[0091] Example 6

[0092] The method of Example 1 is followed, except that the mass concentration of the catalyst is 20 wt % and the density is 1.09 g / cm 3 , the feed volume ratio of polymer suspension and adjusting solvent was 1:0.3.

[0093] The obtained catalyst particles are reusable (>2 μm) with a purity of 99.3% and a catalyst recovery rate of 98.5%.

[0094] Example 7

[0095] The method of Example 1 is followed, except that ethylene glycol is replaced by ethanol, and the rare earth-based catalyst suspension for polymerization and the regulating solvent are first heated to 70° C. and then fed into the separation device.

[0096] The obtained catalyst particles are reusable (>2 μm) with a purity of 98.3% and a catalyst recovery rate of 96%.

[0097] Example 8

[0098] The method of Example 1 is followed, except that the first filter unit and the second filter unit rotate in the same direction and at the same speed (1000 rpm), the third filter unit and the fourth filter unit rotate in the same direction and at the same speed (100 rpm), and the first filter unit and the third filter unit have the same direction. A reusable catalyst particle product (>2 μm) is obtained with a purity of 99% and a catalyst recovery rate of 95%.

[0099] Comparative Example 1

[0100] The method of Example 1 was followed, except that no ethylene glycol was added.

[0101] The obtained catalyst particles are reusable (>2 μm) with a purity of 98% and a catalyst recovery rate of 95%.

[0102] Comparative Example 2

[0103] Take the same rare earth-based catalyst suspension for polymerization as in Example 1, let it stand for 6 hours, then filter it with a filter press (using filter cloth) at room temperature to remove the liquid; stir and mix the filter cake after filter pressing with water (the mass ratio of filter cake to water is 1:1), and wash it; then repeat the above standing, filter pressing, and washing of the material. Perform three rounds of the above standing, filter pressing, and washing. A reusable catalyst particle product (>2μm) is obtained with a purity of 94% and a catalyst recovery rate of 92%.

[0104] Comparative Example 3

[0105] Take the same rare earth-based catalyst suspension for polymerization as in Example 1, first treat it in a conventional centrifuge at 10,000 rpm for 60 minutes, remove the upper layer of water, then wash it with water 3 times the volume of the solid, and finally let it stand and decant to separate and remove the upper layer of water.

[0106] The above centrifugation, washing and separation operations were repeated for three rounds to obtain a reusable catalyst particle product (>2 μm) with a purity of 89% and a catalyst recovery rate of 90%.

[0107] Comparative Example 4

[0108] The method of Example 1 was followed, except that the adjustment solvent was replaced with ethyl acetate to obtain a reusable catalyst particle product (>2 μm) with a purity of 97% and a catalyst recovery rate of 94%.

[0109] It can be seen from the above results that the scheme of the present invention can efficiently achieve the step-by-step separation of catalysts of different particle sizes in the suspension, can be processed in an integrated device, has continuous operation, high processing efficiency, low equipment investment, and can also save space.

[0110] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for continuous separation of a rare earth-based catalyst suspension for polymerization, characterized in that: The method comprises: mixing a rare earth-based catalyst suspension for polymerization with a regulating solvent, and centrifuging the obtained mixture, wherein the centrifugation is performed in a device comprising at least two stages of filtering units to separate catalysts with different particle sizes; Wherein, the regulating solvent is selected from at least one of C2-C8 alcohols, alcohol polymers and C4-C8 ethers.

2. The method according to claim 1, wherein: The C2-C8 alcohol is selected from C2-C6 polyols and / or monohydric alcohols; And / or, the C4-C8 ether is selected from C4-C8 monoether; And / or, the alcohol polymer has a weight average molecular weight of 200-2000 g / mol.

3. The method according to claim 1, wherein: The regulating solvent is selected from at least one of ethylene glycol, propylene glycol, glycerol, cyclohexanol, ethyl ether, propyl ether, butyl ether and polyethylene glycol having a weight average molecular weight of 400-800 g / mol; And / or, the volume ratio of the rare earth-based catalyst suspension for polymerization to the regulating solvent is 1:(0.05-1), preferably 1:(0.1-0.3).

4. The method according to any one of claims 1 to 3, wherein: The solvent in the rare earth-based catalyst suspension for polymerization is selected from at least one of water, ethanol and propanol; And / or, the density of the rare earth-based catalyst suspension for polymerization is 0.7-1.5 g / cm 3 , preferably 0.8-1.1 g / cm 3 ; And / or, in the rare earth-based catalyst suspension for polymerization, the mass concentration of the catalyst is 0.01-20wt%, preferably 0.1-10wt%.

5. The method according to claim 1, wherein: In the rare earth-based catalyst suspension for polymerization, the particle size of the catalyst is 0.05-1000 μm, preferably 0.1-200 μm.

6. The method according to claim 1 or 5, wherein: The rare earth element in the rare earth-based catalyst for polymerization is selected from at least one of yttrium, scandium, zirconium, lanthanum, cerium, praseodymium and neodymium; and / or, the carrier of the rare earth-based catalyst is at least one of silicon dioxide, aluminum oxide, activated carbon and titanium oxide; And / or, the mixing and the centrifuging are each independently performed at a temperature of 20-100°C.

7. The method according to claim 1, wherein: The filtering particle size of the second stage filter unit is such that the particles retained by the second stage filter unit can be directly reused; Preferably, the filtration particle size of the first-stage filter unit is larger than the filtration particle size of the second-stage filter unit.

8. The method according to claim 1 or 7, wherein: The centrifugal speeds of the first stage filtration unit and the second stage filtration unit are independently 50-300 rpm, preferably 80-150 rpm; And / or, the centrifugation time is 60-600 s, preferably 200-400 s.

9. The method according to claim 1 or 7, wherein: The device also includes a third-stage filtration unit; Preferably, the device further comprises a fourth-stage filtering unit.

10. The method according to claim 9, wherein: The centrifugal rotation speeds of the third-stage filter unit and the fourth-stage filter unit are independently 800-10000 rpm, preferably 1000-5000 rpm.

11. The method according to claim 1 or 7, wherein: The method further comprises: during the centrifugation process, spraying an eluent onto the material retained by the first stage filtration unit.

12. The method according to claim 1 or 9, wherein: The method further comprises: after the centrifugation is completed, blowing gas into the device in the opposite direction of the filtered material to purge and / or dry the material attached to each level of the filtering units.

13. The method according to claim 9, wherein: The centrifugal directions of the first-stage filter unit and the second-stage filter unit are the same, the centrifugal directions of the third-stage filter unit and the fourth-stage filter unit are the same, and the centrifugal directions of the first-stage filter unit and the third-stage filter unit are the same or opposite, preferably opposite.

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