Catalyst feed system and process, process for producing olefin polymers, and olefin polymers obtainable by the same

Abstract

This invention relates to a process for feeding a polymerization catalyst into a polymerization reactor, the process comprising the following steps: (i) forming a catalyst slurry comprising oil and solid catalyst components in a first catalyst preparation container; (ii) conveying the catalyst slurry from the first catalyst preparation container to a first catalyst feed container; (iii) maintaining the catalyst slurry in the first catalyst feed container in a homogeneous state; (iv) discharging a portion of the catalyst slurry from the first catalyst feed container, preferably continuously discharging the catalyst slurry from the first catalyst feed container, and introducing the discharged portion of the catalyst slurry into the polymerization reactor; wherein, when located within the first catalyst preparation container and the first catalyst feed container, the dynamic viscosity of the oil is 25 to 1500 mPa*s; wherein the catalyst slurry is conveyed from the first catalyst feed container downward along a substantially vertical path into the polymerization reactor.

Description

Technical Field

[0001] The present invention relates to a process for feeding a polymerization catalyst into a polymerization reactor, a process for producing an olefin polymer in a polymerization reactor, an olefin polymer obtained by the process, and a catalyst slurry feeding system for producing an olefin polymer in a polymerization reactor. Prior Technology

[0002] In the prior art, systems for feeding polymerization catalysts typically comprise two parallel and close-to-each-other containers for feeding the catalyst into the polymerization reactor. The catalyst can be prepared and fed from separate containers, but in practice, at a given time, one container is typically used to prepare the catalyst oil-slurry, and the other container is used for feeding. EP 3241611 discloses a process for feeding a polymerization catalyst into a polymerization reactor, comprising the steps of: (i) maintaining a catalyst slurry containing a diluent and solid catalyst components in a catalyst feed container; (ii) continuously discharging the catalyst slurry stream from the catalyst feed container; and (iii) introducing the discharged portion of the catalyst slurry into the polymerization reactor. In the case of the catalyst feed container, the dynamic viscosity of the diluent is from 0.01 to 20 mPa*s.

[0003] EP 1671697A1 discloses a polymerization process comprising the following steps: (i) forming a catalyst slurry containing oil and solid polymerization catalyst components in a catalyst feed container; (ii) maintaining the slurry in the catalyst feed container in a homogeneous state; and (iii) continuously discharging a portion of the catalyst slurry from the catalyst feed container and introducing the discharged slurry into a polymerization reactor.

[0004] WO 2010 / 086392 A1 describes a method for switching between two different catalysts during continuous olefin polymerization, and more specifically, a method for producing homopolymers or copolymers of polypropylene in a continuous slurry / gas-phase polymerization reaction with a pre-polymerization reaction. The method includes the steps of: a) stopping the feed of a first catalyst into a prepolymerization reactor; then b) introducing a second catalyst into the prepolymerization reactor; and c) adjusting the reaction conditions in the prepolymerization reactor, the slurry reactor, and subsequently the gas-phase reactor. The switching occurs between a Ziegler-Natta catalyst and a self-supported solid metallocene catalyst, wherein the catalyst is prepared using an emulsification / curing technique, and vice versa, thereby enabling the switching to occur in the absence of any additives that would deactivate or kill the catalyst.

[0005] Known feed system layouts typically have the following drawbacks: the container is located quite far from the injection point of the (pre)polymerization reactor. Therefore, in known systems according to prior art, the catalyst feed line can sometimes become clogged due to the length and / or complexity of the piping. Furthermore, pump blockages can also occur during switching from one tank to another.

[0006] Therefore, a process is needed to feed the polymerization catalyst into the polymerization reactor to avoid the above-mentioned drawbacks, especially clogging. Summary of the Invention

[0007] The object of the present invention is achieved by a process for feeding a polymerization catalyst into a polymerization reactor, the process comprising the following steps: (i) forming a catalyst slurry comprising oil and solid catalyst components in a first catalyst preparation container; (ii) conveying the catalyst slurry from the first catalyst preparation container to a first catalyst feed container; (iii) maintaining the catalyst slurry in the first catalyst feed container in a homogeneous state; and (iv) discharging a portion of the catalyst slurry from the first catalyst feed container, preferably continuously discharging the catalyst slurry from the first catalyst feed container, and introducing the discharged portion of the catalyst slurry into the polymerization reactor; wherein, when located in the first catalyst preparation container and the first catalyst feed container, the dynamic viscosity of the oil is 25 to 1500 mPa*s; and wherein the catalyst slurry is conveyed from the first catalyst feed container downward along a substantially vertical path into the reactor.

[0008] Catalyst preparation and catalyst feeding take place in separate containers. This allows the feed container to be placed quite close to the polymerization reactor. The catalyst feed container is positioned above the polymerization reactor, which can also be a prepolymerization reactor. Specifically, "above the polymerization reactor" refers to the position above the injection point of each reactor. It should be understood that since the catalyst feed container is positioned above, it also covers the area diagonally above the corresponding reactor. Importantly, gravity supports the transport from the feed container to the injection point. Therefore, blockages are avoided and the complexity of the feed line can be reduced. It also reduces the load on the pump.

[0009] In addition, the system according to the invention allows for the preparation of catalyst slurry from dry catalyst powder in polyolefin plants because the catalyst preparation container can be placed anywhere in the plant where the catalyst powder can be easily fed. For example, the preparation container can be located near the ground, as this simplifies the feeding of these components. This saves on catalyst transport costs and reduces the time required to feed the catalyst powder into the system. On the other hand, the advantages of preparing catalyst slurry are that the use of a positive displacement pump makes the catalyst feeding in the oil very accurate and reliable. Furthermore, the oil protects the catalyst from catalyst poisoning and makes the disposal of catalyst waste safer, especially when using ignitable catalysts.

[0010] The container and pipeline layout according to the invention prevents clogging. Furthermore, the invention allows plants to feed catalysts at higher slurry concentrations, thereby reducing the amount of oil fed into the process.

[0011] The solid catalyst components used in the process of this invention are suspended in oil to prepare a catalyst slurry.

[0012] The oil is selected from food-approved white oils and mixtures thereof; and / or the catalyst fed into the first catalyst preparation container is a dry catalyst powder; and / or, based on the total amount of the slurry, the concentration of the catalyst in the slurry is 10 to 40 wt%, preferably 15 to 30 wt%, more preferably 20 to 25 wt%.

[0013] The oil used must be inert to the catalyst. This means it must not contain components that readily react with the catalyst, such as groups selected from oxygen, sulfur, nitrogen, chlorine, fluorine, bromine, iodine, etc. Groups containing double or triple bonds should also be avoided. In particular, the presence of compounds such as water, alcohols, organosulfur compounds, ketones, carbon monoxide, carbon dioxide, and alkynes should be avoided.

[0014] The oil is preferably white oil, more preferably food-approved white oil or a mixture of food-approved white oils. White oil can be white mineral oil. White mineral oil is a special mineral oil obtained through deep refining to remove impurities such as aromatic hydrocarbons, sulfur, and nitrogen. It is generally composed of alkanes and cycloalkanes, with a molecular weight of 250 to 400 g / mol, and belongs to the lubricating oil fraction. It is colorless, odorless, chemically inert, and has excellent light and heat stability.

[0015] White mineral oil (i.e., paraffin oil, white oil) is often used as a diluent for catalysts, especially as a diluent for polyolefin polymerization catalysts.

[0016] The food-approved white oil can be food-grade white oil. Food-grade white oil is a special mineral oil product obtained by further refining ordinary white oil products and removing aromatic hydrocarbons. It has excellent light and heat stability, anti-yellowing properties, antioxidant properties, and viscosity temperature performance. It is suitable for human use, safe, and non-toxic. Suitable examples of food-approved white oils are Clarion® Food Grade White Mineral Oil 70, Phillips 66® White Oil, and FOODGUARD USP White Oil 15.

[0017] The oil should have a viscosity that stabilizes the slurry and minimizes the tendency of catalyst particles to settle. Therefore, the oil viscosity should not be too low. On the other hand, the slurry should be easily transported into the polymerization reactor. Very high viscosity leads to problems in catalyst handling, as high-viscosity fluids require special handling. Furthermore, viscous wax residues in the polymer product after polymerization can negatively impact product properties.

[0018] The kinematic viscosity of the oil in the catalyst slurry is preferably 65 to 75 mm² / s. The kinematic viscosity of the oil is measured according to ISO 3104.

[0019] It has been found that optimal results are obtained when the dynamic viscosity of the oil is between 25 and 1500 mPa*s, when the oil is located within both the catalyst preparation vessel and the catalyst feed vessel. Preferably, the dynamic viscosity is between 30 and 1500 mPa*s, and more preferably between 35 and 990 mPa*s, when measured at the operating temperature of the feed vessel. Dynamic viscosity is the product of kinematic viscosity and density.

[0020] In particular, the oil viscosity should be high enough to allow the feed pump to operate. Furthermore, the oil should lubricate the piston of the catalyst feed pump to ensure smooth operation.

[0021] It has been surprisingly found that when the viscosity is selected within the above range, the composition of the catalyst slurry can be easily handled in various process operations, the tendency of catalyst particles to settle during retention in the feed container and pipeline is minimized, and smooth operation of the feed pump is ensured.

[0022] Solid catalyst components can be transported as dry powder, or they can be transported in oil slurry.

[0023] Preferably, the catalyst fed into the catalyst preparation container is a dry catalyst powder.

[0024] If the catalyst is transported as a slurry, the oil used in the slurry is preferably the same as or at least similar to the oil used in the catalyst feed. The concentration of the solid catalyst component in the transported slurry can be as high as 450 kg / m³.

[0025] The concentration of the solid catalyst component can be freely selected, making it easy to obtain the desired catalyst feed rate. However, the concentration cannot be too high, otherwise it may be difficult to maintain slurry stability. On the other hand, too low a concentration may result in the use of excessive oil, which may lead to an increase in the extractable content in the final polymer product.

[0026] The solid catalyst component may contain a polymer. Therefore, it may have been prepolymerized to produce small amounts of polymer on the solid catalyst component, for example, 0.01 to 50 grams of polymer per gram of solid component. The monomer used for prepolymerization may be the same as or different from the monomer used in the polymerization reactor.

[0027] In the process of this invention, the catalyst is selected from the group consisting of Ziegler-Natta catalysts, metallocene catalysts, post-transition metal catalysts, and mixtures thereof. Any solid catalyst composition can be used in the process of this invention.

[0028] The catalyst can be of the Ziegler-Natta type. For example, it can comprise magnesium and titanium compounds supported on an inorganic oxide support, as disclosed in EP 688794, WO 91 / 16361, WO 93 / 13141, WO 94 / 14857, WO 99 / 51646, and WO 01 / 55230. However, it can also comprise titanium compounds supported on magnesium halides, as disclosed in WO 03 / 000756, WO 03 / 000757, WO 03 / 000754, WO 92 / 19653, WO 93 / 07182, WO 97 / 36939, and WO 99 / 58584. The catalyst can also be unsupported, comprising solid titanium trichloride particles, optionally containing additional components such as aluminum trichloride.

[0029] The catalyst can also be a chromium catalyst, which is typically supported on silicon dioxide. Such catalysts are disclosed in particular in WO 99 / 52951 and WO 97 / 27225.

[0030] Furthermore, the catalyst can be a metallocene catalyst. Typically, such catalysts are supported, preferably on an inorganic oxide support, as disclosed in WO 95 / 12622, WO 96 / 32423, WO 98 / 32776, and WO 00 / 22011. However, the catalyst can also be prepared by forming a support from an aluminoxane and incorporating the metallocene compound onto the aluminoxane. A method for preparing such solid metallocene catalyst compositions is disclosed in WO 03 / 051934.

[0031] The catalyst slurry can be formed by any method known in the art to which this invention pertains. According to a preferred method, the solid catalyst components are introduced into the oil under stirring.

[0032] A slurry is prepared in the first catalyst preparation vessel.

[0033] Preferably, a homogeneous slurry is prepared in the first catalyst preparation vessel. The slurry is kept homogeneous by agitation. Agitation can be achieved by circulating the slurry using a circulation pump and piping connecting the pump to the first catalyst feed vessel. Alternatively, the first catalyst feed vessel is equipped with an agitator that keeps the slurry in motion within the feed vessel. Preferably, the first catalyst feed vessel is equipped with an agitator. The elements of the agitator should be selected to achieve uniform agitation throughout the entire volume of the first catalyst feed vessel, without any dead zones where catalyst may settle. These agitator elements are well known in the art to which this invention pertains, such as anchor elements and axial and radial impellers, and those skilled in the art can select suitable combinations for various geometries of the first catalyst feed vessel. The first catalyst feed vessel may also be equipped with baffles known in the art to which this invention pertains to further improve agitation.

[0034] As is known to those skilled in the art to which this invention pertains, the stirring speed N should be selected such that N... Njs, where Njs is the speed at which the agitator just stopped, and can be calculated using a formula available in the technical field to which this invention pertains, for example, from Zwietering Th.N., "Suspending of solids particles in liquid by agitators", Chem Eng Sci, Vol 8, pp 244-254, 1958. Preferably, the rotational speed N of the agitator is 50 to 75 rpm.

[0035] The pressure within the preparation vessel is not critical and can be selected within the operating range of the process equipment. In particular, it should be selected to allow the pump to operate normally. Ideally, the pressure within the preparation vessel should be higher than atmospheric pressure to minimize the final leakage of air and / or moisture into the preparation vessel.

[0036] The preparation vessel must be kept in an inert environment. The presence of oxygen and moisture should be avoided in particular. Therefore, all connections to the preparation vessel, such as pipe joints and agitator bearings, need to be carefully designed to eliminate leakage from the environment.

[0037] The gas in the preparation container is preferably composed of nitrogen, argon, or similar inert gases, or mixtures thereof. Furthermore, the preparation container should be capable of being flushed with an inert gas, preferably nitrogen.

[0038] In addition, process chemicals such as lubricants used in bearings need to be selected to be free of components that are harmful to the catalyst, or to prevent them from being carried into the preparation container.

[0039] In step (ii), the catalyst slurry is transported from the first catalyst preparation container to the first catalyst feed container via the catalyst delivery pipeline.

[0040] Preferably, air pressure is applied or a pump is used to transport the catalyst slurry from the first catalyst preparation vessel to the first catalyst feed vessel.

[0041] More preferably, a second catalyst preparation vessel is provided. The catalyst slurry can be formed independently in both preparation vessels.

[0042] The features of the first catalyst preparation vessel described above also apply to the second catalyst preparation vessel.

[0043] More preferably, the catalyst slurry is transported from the first catalyst preparation vessel and the second catalyst preparation vessel to the first catalyst feed vessel via the first catalyst delivery line. Alternatively, a second catalyst feed vessel may be present, into which the slurry can be transported.

[0044] The temperature of the slurry within the catalyst feed vessel is not critical. However, excessively low or high temperatures should be avoided, otherwise the slurry viscosity may become too high, making it difficult to handle in the process, or the slurry viscosity may become too low, causing particles to settle easily. The temperature can be selected within the range of -30°C to +80°C, preferably within the range of 0°C to 60°C.

[0045] Preferably, the catalyst feed vessel is equipped with a heating / cooling jacket to maintain the temperature within the vessel at a desired level. In particular, the slurry temperature should be regulated so that the oil viscosity is within desired limits. Furthermore, temperature variations should be avoided, as they lead to changes in slurry density. If the slurry density changes, the catalyst feed rate will change accordingly, which can cause fluctuations during polymerization.

[0046] The feed rate should be controlled based on the catalyst and production rate. A more stable feed rate is better.

[0047] The pressure within the catalyst feed vessel is not critical and can be selected within the operating range of the process equipment. In particular, it should be selected to allow the pump to operate normally. Ideally, the pressure within the catalyst feed vessel should be higher than atmospheric pressure to minimize the final leakage of air and / or moisture into the catalyst feed vessel.

[0048] The catalyst feed vessel must be kept in an inert environment. The presence of oxygen and moisture should be avoided in particular. Therefore, all connections to the feed vessel, such as pipeline joints and agitator bearings, need to be carefully designed to eliminate leakage from the environment.

[0049] Furthermore, process chemicals, such as lubricants used in bearings, need to be selected to be free of components harmful to the catalyst, or to prevent them from being carried into the catalyst feed vessel. Ideally, the same oil used as a diluent in the catalyst slurry should be used as the lubricant.

[0050] The gas in the catalyst feed vessel is preferably composed of nitrogen, argon, and similar inert gases, or mixtures thereof. Furthermore, the catalyst feed vessel should be capable of being flushed with an inert gas, preferably nitrogen.

[0051] Optionally, the catalyst slurry may come into contact with the activator and / or electron preform in the following situations: in the preparation vessel; or before being introduced into the polymerization reactor; or before being introduced into the pipeline before being introduced into the polymerization reactor.

[0052] The catalyst slurry may contain additional components such as activators, electron preforms, modifiers, antistatic agents, etc. If such components are used, they can be combined with the catalyst slurry in the catalyst feed vessel; or they can be combined with the catalyst slurry stream to be introduced into the polymerization reactor; or they can be introduced directly into the polymerization reactor without pre-contact with the catalyst slurry.

[0053] As useful activators, organometallic compounds, such as organoaluminum compounds, especially alkylaluminum, can be used. Examples of such preferred compounds are: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and isoprenyl aluminum. Other useful compounds are: methylaluminoxane, triisobutylaluminoxane, hexaisobutylaluminoxane and other aluminoxanes, dimethylaluminum chloride, diethylaluminum chloride, methylaluminum sesquichloride, ethylaluminum sesquichloride, diethylzinc, and triethylboron.

[0054] Examples of electronic precursors can be ethers, esters, ketones, alcohols, carboxylic acids, silicone ethers, aceimides, aceamines, and amines.

[0055] A small amount of drag-reducing agent can also be added to the catalyst slurry. Such drag-reducing agents are typically soluble polymers of higher α-olefins, such as C6 to C15 α-olefins, preferably C8 to C13 α-olefins. They may also contain a small amount of comonomer units derived from other olefins. However, it is important that the drag-reducing agent be soluble in oil. The amount of drag-reducing agent used is 0.1 to 1000 ppm by weight of the catalyst slurry, preferably 0.5 to 100 ppm, and more preferably 1 to 50 ppm. It has been found that this small amount has reduced the slurry's tendency to settle. While there are no disadvantages to excessive drag-reducing agent from a process perspective, it should be remembered that the drag-reducing agent may remain in the polymer product, and, if used in large quantities, it may negatively affect certain product properties.

[0056] Drag reducers are commercially available, particularly supplied by MI Production Chemicals and Conocon. The former supplies a product under the brand name NECADD 447TM, which has been found useful in preventing catalyst particle sedimentation. The drag reducers typically have a weight-average molecular weight of at least 250,000 g / mol, preferably at least 500,000 g / mol, and more preferably at least 800,000 g / mol. In particular, the drag reducers have a weight-average molecular weight greater than 1,000,000 g / mol.

[0057] According to a preferred embodiment, the process of the present invention uses a second catalyst preparation container, a first catalyst feed container, and a second catalyst feed container, wherein the catalyst slurry in the first catalyst preparation container is transported to the first catalyst feed container via a first catalyst delivery pipeline, and the catalyst slurry in the second catalyst preparation container is transported to the second catalyst feed container via a second catalyst delivery pipeline.

[0058] The features of the first catalyst preparation vessel described above also apply to the second catalyst preparation vessel.

[0059] A process with two catalyst preparation vessels and two catalyst feed vessels, and separate delivery lines, can improve operational flexibility, thereby increasing process throughput. Furthermore, the process may include two catalyst preparation vessels and two catalyst feed vessels, with non-separate, preferably cross-connected delivery lines.

[0060] The intersecting feed lines include a switching system. The first and second feed lines may also intersect each other and may also include a switching system. The switching system can switch between using the first feed line or the second feed line to deliver catalyst slurry from the first or second catalyst preparation vessel to the first or second catalyst feed vessel; and the switching system can also switch between using the first or second feed line to deliver a portion of the catalyst slurry discharge from the first or second catalyst feed vessel to the polymerization reactor. Preferably, the switching system includes two or more valves.

[0061] Keep the catalyst slurry in a uniform state (step (iii)).

[0062] A portion of the slurry can be continuously discharged from the catalyst feed container and introduced into the polymerization reactor.

[0063] In step (iv), the catalyst slurry is fed from the first catalyst feed vessel and / or the second catalyst feed vessel into the polymerization reactor using at least one valveless piston pump. The valveless piston pump is positioned at a height lower than that of the catalyst feed vessel.

[0064] Valveless piston pumps are ideal for use with high-viscosity fluids and fluids containing particles or colloids. Valveless piston pumps operate with high accuracy.

[0065] In the process of this invention, the transport from the first catalyst preparation container to the first catalyst feed container and / or from the second catalyst preparation container to the second catalyst feed container can be performed in batches, preferably in batches. Therefore, the velocity in the pipeline can be so high that settling will not occur.

[0066] In the process of this invention, oil and / or N2 can be used to purge at least one of the delivery lines. The delivery lines extending from the catalyst preparation vessel to the catalyst feed vessel are pneumatically operated under N2 pressure.

[0067] Preferably, the catalyst slurry discharged from the catalyst feed container and introduced into the polymerization reactor is transported from the catalyst feed container to the polymerization reactor via at least one feed line.

[0068] Preferably, the length of the at least one feed line is 2 to 12 m; more preferably, the length of all feed lines is 2 to 12 m. Even more preferably, the length of the at least one feed line is 5 to 12 m, and even more preferably 10 to 12 m.

[0069] Optionally, the process of the present invention includes the step of monitoring the liquid level of the catalyst slurry through a liquid level sensor in a catalyst feed container, wherein the catalyst feed container is preferably the first catalyst feed container and the second catalyst feed container. Furthermore, a liquid level measuring device may be disposed in a catalyst preparation container, and / or, the liquid level measurement may be performed in the step of monitoring the liquid level of the catalyst slurry through a liquid level sensor in a catalyst preparation container; wherein the catalyst preparation container is preferably the first catalyst preparation container and the second catalyst preparation container.

[0070] A level sensor installed in the catalyst feed container can estimate the level of the catalyst slurry. For example, a radioactive level measuring instrument can be used. It can be used to measure the level of concentrated (or settled) slurry in the feed container, as well as the level of homogeneous slurry. By using the level sensor, the operator can prepare a new batch of catalyst slurry in the preparation container. When the catalyst slurry (or concentrated catalyst slurry) in the first catalyst feed container is depleted, the operator can then stop draining the catalyst slurry from the first catalyst feed container and begin draining the catalyst slurry from the second catalyst feed container, or transfer a new batch of catalyst slurry from the preparation container to the catalyst feed container.

[0071] Small portions of the slurry can also be continuously or intermittently transferred from the preparation vessel to the catalyst feed vessel. When using such a procedure, the level of the catalyst slurry or concentrated catalyst slurry in the catalyst feed vessel can be kept substantially constant.

[0072] Other sensors that can be installed in the system of the present invention include, for example, gas sensors, pressure sensors, temperature sensors, and electrostatic sensors.

[0073] The present invention provides the following additional steps: stopping the discharge of catalyst slurry from one of the first catalyst feed container or the second catalyst feed container, and starting the discharge of catalyst slurry from the other of the first catalyst feed container or the second catalyst feed container in response to a signal from a level sensor.

[0074] Another aspect of the present invention relates to a process for producing olefin polymers in a polymerization reactor, the process comprising the step of feeding a polymerization catalyst into the polymerization reactor using the process described above.

[0075] Preferably, the process for producing olefin polymers in a polymerization reactor includes the step of feeding a polymerization catalyst into the polymerization reactor using the process described above. The process includes the following steps: (i) continuously introducing at least one olefin monomer into the polymerization reactor; (ii) optionally, continuously introducing a diluent and / or hydrogen into the polymerization reactor; (iii) operating the polymerization reactor while polymerizing the at least one olefin monomer through the polymerization catalyst to form a reaction mixture, wherein the reaction mixture comprises the catalyst, unreacted monomer, the formed polymer, and optionally a diluent and / or hydrogen; and (iv) optionally, discharging a portion of the reaction mixture from the polymerization reactor.

[0076] In some cases, preferably, a prepolymerization stage is performed before the polymerization stage. A small amount of olefin is polymerized in the prepolymerization, preferably 0.1 to 500 grams of olefin per gram of catalyst. Prepolymerization is typically carried out at a lower temperature and / or a lower monomer concentration than the actual polymerization. Typically, prepolymerization is carried out at 0 to 70°C, preferably 10 to 60°C. The monomers used in the prepolymerization are typically, but not necessarily, the same as those used in the subsequent polymerization stage. More than one monomer may also be fed into the prepolymerization stage. Descriptions of prepolymerization can be found, for example, in WO 96 / 18662, WO 03 / 037941, GB 1532332, EP 517183, EP 560312, and EP 99774.

[0077] During the polymerization process, α-olefins having 2 to 20 carbon atoms can be polymerized. In particular, ethylene and / or propylene are optionally polymerized with higher α-olefins. Preferably, 1-butene and 1-hexene are used as comonomers.

[0078] The diluent can be any liquid that is inert to the catalyst. A suitable diluent is a hydrocarbon having at least three carbon atoms. Preferably, the diluent is selected from the group consisting of C3 to C10 hydrocarbons and mixtures thereof. Specifically, the diluent is selected from the group consisting of propane, n-butane, isobutane, n-pentane, isopentane, and mixtures thereof.

[0079] Polymerization occurring in at least one polymerization stage falls within the scope of this invention. The art to which this invention pertains also knows of polymerizing in at least two polymerization stages to produce bimodal polyolefins, such as bimodal polyethylene and bimodal polypropylene, as disclosed in WO 92 / 12182, EP 22376, EP 713888, and WO 98 / 58975. Furthermore, multi-stage polymerization can be used to produce heterophasic propylene copolymers, as disclosed in WO 98 / 58976. It should be understood that this invention is not limited to any particular number of polymerization stages, but any number is possible.

[0080] If the polymerization is carried out as a slurry polymerization, any suitable reactor type known in the art to which this invention pertains can be used. Continuous stirred tank reactors and circulating reactors are suitable examples of useful reactor types. In particular, circulating reactors are preferred due to their flexibility.

[0081] Slurry polymerization can be carried out in a normal liquid slurry state, or it can be carried out such that the temperature and pressure within the reactor exceed the critical temperature and pressure of the fluid mixture within the reactor. This type of polymerization method is called supercritical slurry polymerization. Liquid slurry polymerization is described in EP 249689 and US 3262922, while supercritical slurry polymerization is described in WO 92 / 12181 and US 3294772.

[0082] The slurry can be discharged from the reactor by any method known in the art to which this invention pertains, including continuous and intermittent discharge. If the discharge is intermittent, it can be achieved by using a so-called settling leg, which allows the slurry to settle before being discharged from the reactor. Settling legs are generally known in the art, and they are described, for example, in US 4613484 and US 4121029.

[0083] If the slurry is continuously discharged from the reactor, it can be discharged without a concentration step, or concentration can be performed before or after discharge. For economic reasons, it is preferable to concentrate the slurry. Suitable concentration methods are, in particular, hydrocyclones or sieves. Typically, in such methods, the slurry is continuously discharged from the reactor through a concentration device, such as a hydrocyclone or sieve. The underflow is directed to the product discharge point, while the overflow is recycled back to the polymerization reactor. Such methods are disclosed in EP 1415999.

[0084] On the other hand, the present invention provides an olefin polymer obtained by the above-described process of producing an olefin polymer in a polymerization reactor, the process including the step of feeding a polymerization catalyst into the polymerization reactor using the process of the present invention as described above.

[0085] An olefin polymer can be obtained from the above process. The polymer obtained by this process includes all olefin polymers and copolymers known in the art to which this invention pertains, such as: high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), polypropylene homopolymers, random copolymers of propylene and ethylene or random copolymers of propylene and higher α-olefins, heteroophasic copolymers of propylene and ethylene, poly-1-butene, and poly-4-methyl-1-pentene. When higher α-olefins are used as comonomers, they are preferably selected from the group consisting of 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene.

[0086] On the other hand, the present invention provides a catalyst slurry feeding system for producing olefin polymers in a polymerization reactor, comprising: a first catalyst preparation container, preferably at least two catalyst preparation containers, for forming a catalyst slurry containing oil and solid catalyst components; a first catalyst feed container, preferably at least two catalyst feed containers, for maintaining the catalyst slurry in a homogeneous state; a polymerization reactor; a first conveying line connecting the first catalyst preparation container to the first catalyst feed container, preferably two conveying lines connecting the at least two catalyst preparation containers to the at least two catalyst feed containers; a first feed line connecting the first catalyst feed container to the polymerization reactor, preferably at least two feed lines connecting the at least two catalyst feed containers to the polymerization reactor; wherein the first feed line is provided with a pump, preferably the at least two feed lines are provided with at least one pump; and the first catalyst feed container is located above the polymerization reactor, preferably the at least two catalyst feed containers are located above the polymerization reactor.

[0087] Preferably, the catalyst slurry feeding system for producing olefin polymers in a polymerization reactor includes a second catalyst preparation container, wherein the first catalyst preparation container is connected to a first catalyst feed container via a first delivery line, and the second catalyst preparation container is connected to a second catalyst feed container via a second delivery line.

[0088] Preferably, the length of the first feed line is 2 to 12 m; more preferably, the length of all feed lines is 2 to 12 m. Even more preferably, the length of the first feed line and / or the at least two feed lines is 5 to 12 m, more preferably 10 to 12 m.

[0089] The feed line may be equipped with a catalyst flow meter. Flow meters suitable for measuring catalyst feed rates are disclosed in WO 2004 / 057278 and are available, in particular, from Oxford Instruments. Such flow meters can also be used as part of a control loop to control the catalyst feed rate. For example, the signal from the flow meter is compared to a predetermined setpoint, and the signal sent to the metering pump is adjusted based on the difference.

[0090] The aforementioned system allows for the separation of catalyst preparation from its feeding into the process. Therefore, the catalyst preparation container can be located at a distance from the injection point of the polymerization reactor, and the catalyst feed container can be positioned as close as possible to the injection point. By placing the catalyst feed container above the polymerization reactor, gravity supports the transport of the catalyst slurry to the reactor.

[0091] Preferably, the catalyst feed container is located above the injection point of the polymerization reactor.

[0092] Preferably, the catalyst feed container is located vertically above or obliquely above the polymerization reactor; more preferably, the at least two catalyst feed containers are located vertically above or obliquely above the polymerization reactor.

[0093] The location of the preparation vessel can be freely chosen. Typically, the location depends on the overall system structure. Furthermore, a structured selection of location simplifies the feeding of the preparation vessel. However, the preparation vessel can be located below the height of the catalyst feed vessel. Preferably, the preparation vessel is located below the catalyst feed vessel.

[0094] This type of system has two catalyst preparation containers and two catalyst feed containers with separate delivery lines, which can increase the production capacity of olefin polymers.

[0095] All the embodiments discussed for the process of feeding a polymerization catalyst into a polymerization reactor are also applicable to catalyst slurry feeding systems for the production of olefin polymers. Simple Explanation of the Diagram

[0096] Figure 1 shows a system for the process of the present invention, including a catalyst preparation vessel, a catalyst feed vessel, a catalyst feed pump, and a polymerization reactor; Figure 2 shows another system for the process of the present invention, including two catalyst preparation vessels, two catalyst feed vessels, two catalyst feed pumps, and a polymerization reactor; and Figure 3 shows a system for the process of the present invention, having intersecting delivery lines, intersecting feed lines, and two switching systems. Implementation

[0097] Figure 1 shows an embodiment of the process of the present invention. The process includes: a catalyst preparation container (1), a catalyst feed container (3), a catalyst feed pump (4), and a polymerization reactor (6). The catalyst preparation container (1) may be located on the ground for easy access. A catalyst slurry is formed in the catalyst preparation container (1), and then the catalyst slurry is conveyed to the catalyst feed container (3) via a catalyst delivery line (2). The conveying from the catalyst preparation container to the catalyst feed container can be done in batches. Preferably, the catalyst feed container (3) is located at a height higher than the catalyst preparation container (1). Therefore, the conveying of the catalyst slurry from the catalyst preparation container (1) to the catalyst feed container (3) is substantially upward. Meanwhile, the catalyst slurry in a homogeneous state is discharged from the bottom of the operating catalyst feed container (3). The discharged portion of the catalyst slurry is conveyed to the polymerization reactor (6) via a feed line (5) using, for example, a valveless piston pump (4). The catalyst feed container (3) is located above the polymerization reactor (6).

[0098] Figure 2 shows another embodiment of the process of the present invention. This process includes: two catalyst preparation containers (11, 12), two catalyst feed containers (31, 32), two catalyst feed pumps (41, 42), and a polymerization reactor (6). The catalyst slurry in the first catalyst preparation container (11) is conveyed to the first catalyst feed container (31) via a first catalyst delivery line (21), and the catalyst slurry in the second catalyst preparation container (12) is conveyed to the second catalyst feed container (32) via a second catalyst delivery line (22). Preferably, the catalyst feed containers (31, 32) are located at a height higher than the polymerization reactor (6). The discharge portion of the catalyst slurry from the catalyst feed containers (31, 32) is conveyed via two feed lines (51, 52) to, for example, two valveless piston pumps (41, 42), and then via two reactor feed lines (71, 72) to the polymerization reactor (6).

[0099] Figure 3 shows another embodiment of the process of the present invention. Figure 3 shows a flowchart similar to the system shown in Figure 2. However, in the system shown in Figure 3, the first catalyst delivery lines (211, 212) and the second catalyst delivery lines (221, 222) connecting the first catalyst preparation container (11) and the second catalyst preparation container (12) to the first catalyst feed container (31) and the second catalyst feed container (32) intersect each other. The first feed lines (511, 512) and the second feed lines (521, 522) from the first catalyst feed container (31) and the second catalyst feed container (32) to the valveless piston pumps (41, 42) also intersect each other.

[0100] The catalyst slurry in the first catalyst preparation container (11) is conveyed to the first catalyst feed container (31) via the first catalyst delivery lines (211, 212), and thus will pass through a first switching system (23) located between the first section (211) and the second section (212) of the first catalyst delivery lines. The first switching system (23) includes two or more valves and can be configured to convey the catalyst slurry to the first catalyst feed container (31) via the second section (212) of the first catalyst delivery lines, or to the second catalyst feed container (32) via the second section (222) of the second catalyst delivery lines. The catalyst slurry in the second catalyst preparation container (12) is conveyed to the second catalyst feed container (32) via the first section (221) of the second catalyst delivery lines, and thus will pass through the first switching system (23). The first switching system (23) can be configured to deliver the catalyst slurry to the second catalyst feed container (32) via the second part (222) of the second catalyst delivery line, or to the first catalyst feed container (31) via the second part (212) of the first catalyst delivery line.

[0101] The discharge portion of the catalyst slurry from the catalyst feed containers (31, 32) is conveyed to valveless piston pumps (41, 42) via the first feed line (511, 512) and the second feed line (521, 522) and the second switching system (53), and then conveyed to the polymerization reactor (6) via two reactor feed lines (71, 72). The discharge portion from the first catalyst feed container (31) is conveyed to the second switching system (53) via the first section (511) of the first feed line; then conveyed to the valveless piston pump (41) via the second section (512) of the first feed line, or conveyed to another valveless piston pump (42) via the second section (522) of the second feed line. The discharge portion from the second catalyst feed container (32) can be conveyed via a first section (521) of the second feed line to a second switching system (53); then via a second section (522) of the second feed line to a valveless piston pump (42), or via a second section (512) of the first feed line to another valveless piston pump (41). The desired pipeline can be selected via the switching system. This process provides greater flexibility in the preparation and feeding of the catalyst slurry.

[0102] Unless otherwise expressly stated, the description of the invention should be understood to mean that any one or more of the preferred embodiments described above can be combined with the invention described in its most general form. Furthermore, it will be understood that variations or alternatives to the features and functions disclosed above, as well as other features and functions, can be incorporated into many other different systems or applications. Those skilled in the art to which this invention pertains will subsequently be able to make various alternatives, modifications, variations, or improvements not currently foreseen or anticipated herein, and these are intended to be covered by the claims of this invention.

[0103] 1: Catalyst preparation container

[0104] 11: Catalyst preparation container, first catalyst preparation container

[0105] 12: Catalyst preparation container, second catalyst preparation container

[0106] 2: Catalyst delivery pipeline

[0107] 21: First catalyst delivery pipeline

[0108] 211: First catalyst delivery pipeline, first part of the first catalyst delivery pipeline

[0109] 212: First catalyst delivery pipeline, second part of the first catalyst delivery pipeline

[0110] 22: Second catalyst delivery pipeline

[0111] 221: Second catalyst delivery pipeline, first section of the second catalyst delivery pipeline

[0112] 222: Second catalyst delivery pipeline, second section of the second catalyst delivery pipeline

[0113] 23: First Switching System

[0114] 3: Catalyst feed container

[0115] 31: Catalyst feed container, first catalyst feed container

[0116] 32: Catalyst feed container, second catalyst feed container

[0117] 4: Catalyst feed pump, valveless piston pump

[0118] 41: Catalyst feed pump, valveless piston pump, first catalyst feed pump

[0119] 42: Catalyst feed pump, valveless piston pump, second catalyst feed pump

[0120] 5: Feed line

[0121] 51: Feed line, first feed line

[0122] 511: First feed line, first part of the first feed line

[0123] 512: First feed line, second part of the first feed line

[0124] 52: Feed line, second feed line

[0125] 521: Second feed line, first part of the second feed line

[0126] 522: Second feed line, second part of the second feed line

[0127] 53: Second Switching System

[0128] 6: Polymerization reactor

[0129] 7: Reactor feed line

[0130] 71: Reactor feed line, first reactor feed line

[0131] 72: Reactor feed line, second reactor feed line

Claims

1. A process for feeding a polymerization catalyst into a polymerization reactor, the process comprising the steps of: (i) forming a catalyst slurry comprising oil and solid catalyst components in a first catalyst preparation container; (ii) conveying the catalyst slurry from the first catalyst preparation container to a first catalyst feed container; (iii) maintaining the catalyst slurry in the first catalyst feed container in a homogeneous state; and (iv) discharging a portion of the catalyst slurry from the first catalyst feed container and introducing the discharged portion of the catalyst slurry into the polymerization reactor; wherein, When located within the first catalyst preparation container and the first catalyst feed container, the dynamic viscosity of the oil is 25 to 1500 mPa*s, wherein the catalyst slurry is conveyed from the first catalyst feed container downward along a substantially vertical path to the polymerization reactor, wherein the first catalyst feed container is located vertically above or obliquely above the polymerization reactor.

2. The process as described in claim 1, further comprising providing a second catalyst preparation container, wherein, The catalyst slurry from the first catalyst preparation container and the second catalyst preparation container is transported to the first catalyst feed container via the first catalyst delivery pipeline.

3. The process as described in claim 1, further comprising providing a second catalyst preparation container and a second catalyst feeding container, wherein, The catalyst slurry in the first catalyst preparation container is transported to the first catalyst feed container via the first catalyst delivery pipeline, and the catalyst slurry in the second catalyst preparation container is transported to the second catalyst feed container via the second catalyst delivery pipeline.

4. The process as described in claim 3, wherein, The catalyst slurry from the first catalyst feed vessel and / or the second catalyst feed vessel is fed into the polymerization reactor using at least one valveless piston pump; and / or wherein, The second catalyst feed container is located vertically or diagonally above the polymerization reactor.

5. The process as described in claim 3, wherein, The oil is white oil or food-approved white oil; and / or wherein, when located within the first catalyst preparation container and / or the second catalyst preparation container and the first catalyst feed container and / or the second catalyst feed container, the dynamic viscosity of the oil is 30 to 1500 mPa*s; and / or wherein the catalyst fed into the first catalyst preparation container and / or the second catalyst preparation container is a dry catalyst powder; and / or wherein, based on the total amount of the catalyst slurry, the concentration of the catalyst in the catalyst slurry is 10 to 40 wt%.

6. The process as described in claim 1, wherein, The catalyst is selected from the group consisting of Ziegler-Natta catalysts, metallocene catalysts, post-transition metal catalysts, and mixtures thereof.

7. The process as described in claim 3, wherein, The transport from the first catalyst preparation container to the first catalyst feed container and / or from the second catalyst preparation container to the second catalyst feed container is carried out in batches.

8. The process described in any one of claims 2 to 7, wherein, The oil and / or N2 can be used to purge at least one of the aforementioned delivery lines.

9. The process described in any one of claims 3 to 7, further comprising: The step of monitoring the liquid level of the catalyst slurry through level sensors in the first catalyst feed container and the second catalyst feed container; The step of monitoring the liquid level of the catalyst slurry through level sensors in the first catalyst preparation container and the second catalyst preparation container.

10. The process as described in claim 9, further comprising the steps of: stopping the discharge of the catalyst slurry from one of the first catalyst feed container and the second catalyst feed container, and starting the discharge of the catalyst slurry from the other of the first catalyst feed container and the second catalyst feed container in response to a signal from the level sensor of the first catalyst feed container and the second catalyst feed container.

11. A process for producing olefin polymers in a polymerization reactor, comprising the step of feeding a polymerization catalyst into the polymerization reactor using a process as described in any one of claims 1 to 10.

12. The process for producing an olefin polymer in a polymerization reactor as described in claim 11, further comprising the steps of: (i) continuously introducing at least one olefin monomer into the polymerization reactor; (ii) optionally, continuously introducing a diluent and / or hydrogen into the polymerization reactor; (iii) operating the polymerization reactor while polymerizing the at least one olefin monomer through the polymerization catalyst to form a reaction mixture, wherein, The reaction mixture comprises the polymerization catalyst, unreacted olefin monomers, the formed polymer, and the optional diluent and / or hydrogen; and (iv) optionally, a portion of the reaction mixture is discharged from the polymerization reactor.

13. An olefin polymer obtained by the process described in claim 11 or 12.

14. A catalyst slurry feeding system for producing olefin polymers in a polymerization reactor, comprising: A first catalyst preparation container for forming a catalyst slurry containing oil and solid catalyst components; a first catalyst feed container for maintaining the catalyst slurry in a homogeneous state; a polymerization reactor; a first delivery line connecting the first catalyst preparation container to the first catalyst feed container; a first feed line connecting the first catalyst feed container to the polymerization reactor; wherein the first feed line is equipped with a pump; and wherein the first catalyst feed container is located above the polymerization reactor.

15. The system as described in claim 14, wherein, The system further includes a second catalyst preparation container connected to a second catalyst feed container via a second delivery line; and / or wherein, The first and second catalyst feed containers are located above the injection point of the polymerization reactor, or vertically above the injection point of the polymerization reactor.

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