Polyolefin catalyst prepolymerization method and polyolefin polymerization method and application thereof

Abstract

The present invention relates to the field of olefin polymerization, and discloses a method for prepolymerization of polyolefin catalysts and a method for prepolymerization of polyolefins and applications thereof. The method comprises: in a prepolymerization reactor, olefin monomers are contacted with a polyolefin catalyst composition for prepolymerization reaction to obtain prepolymerization catalyst slurry, and the prepolymerization catalyst slurry is transported to a main reactor; the temperature of the prepolymerization catalyst slurry transported to the main reactor is controlled to be ≤20°C and the flow rate is >0.1m / s. The method for prepolymerization of polyolefin catalysts or the method for polymerization of polyolefins can significantly reduce the risk of scaling and blockage of the main reactor delivery pipeline and improve the operation stability of the device.

Description

Technical Field

[0001] The invention relates to the field of olefin polymerization, and in particular to a polyolefin catalyst prepolymerization method and a polyolefin polymerization method and applications thereof. Background Art

[0002] Since the discovery of Ziegler-Natta (ZN) catalysts and metallocene polyolefin catalysts, the main driving force for their continuous development and progress has been the demand for industrial development. The premise of meeting industrial demand is to obtain catalysts with high polymerization activity and excellent stereoisotacticity, thereby simplifying polymerization technology. In terms of improving catalyst activity, research on catalyst preparation, carriers, internal electron donors, polymerization monomers, and polymerization processes has always been a hot topic, so high-activity catalysts and even ultra-high-activity catalysts have been developed. Modern polyolefin catalysts have high catalytic activity. When they directly enter the main reactor, they will break the polymer "replication" catalyst particles due to high initial activity and violent reaction, resulting in a large amount of polymer fine powder. In severe cases, electrostatic scaling, particle bridge blockage or other poor solid flow phenomena will cause the device to operate unstably, or even shut down the device. At present, a major control method is to conduct a prepolymerization reaction before the catalyst enters the main reactor. While ensuring the activity of the catalyst, it can also improve the polymer morphology and improve the stability of the device operation.

[0003] At present, prepolymerization technology is mainly divided into two forms: continuous prepolymerization and intermittent prepolymerization. Continuous prepolymerization usually controls the catalyst prepolymerization ratio by adjusting the operating temperature of the prepolymerization reactor and the α-olefin flow rate (determines the residence time of the catalyst). Generally, the prepolymerization ratio is above 10 times, preferably at least 50 times. Intermittent prepolymerization technology is mainly used in gas phase polymerization devices, such as the Hypol polypropylene process and the HORIZONE gas phase polypropylene process. Such processes usually activate the catalyst during the catalyst preparation stage, and then prepolymerize it with a trace amount of propylene. The prepolymerization ratio is usually low (<10 times). The prepolymerized catalyst is continuously or intermittently transported to the gas phase reactor by an inert solvent, an inert gas or an α-olefin.

[0004] Although continuous prepolymerization or intermittent prepolymerization can improve the stability of device operation, the position of the pipeline of the prepolymerization catalyst entering the main reactor and the position of the reactor interface are still the positions with higher risk of blockage, especially for ultra-high activity catalysts, initial high activity catalysts or catalysts with poor particle shape. Conventional solutions are to increase the flow rate (flow) of the catalyst delivery medium or extend the catalyst prepolymerization residence time, such as patent CN109906234A reduces the risk of pipeline blockage by increasing the flow rate of the catalyst injection main reactor. The inner diameter of the catalyst delivery pipeline is affected by the size of the catalyst particle size, and generally has a minimum lower limit value, and increasing the flow rate of the delivery medium (especially inert solvent or inert gas) will reduce the prepolymerization time, and will bring in a large amount of inert medium, which will also have a certain impact on the stable control of the product. Extending the continuous prepolymerization time requires a lower continuous α-olefin flow rate, which is unfavorable for catalyst delivery, so increasing the catalyst delivery flow rate (flow) and extending the prepolymerization time are contradictory. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for prepolymerization of polyolefin catalyst and its application and a method for polymerization of polyolefin and its application in view of the above-mentioned deficiencies in the prior art. The method for prepolymerization of polyolefin catalyst or the method for polymerization of polyolefin can significantly reduce the risk of scaling and clogging of the pipeline for transporting the catalyst into the main reactor and improve the operation stability of the device.

[0006] In order to achieve the above object, the present invention provides a method for prepolymerization of polyolefin catalysts, characterized in that the method comprises: in a prepolymerization reactor, olefin monomers are contacted with a polyolefin catalyst composition for prepolymerization reaction to obtain a prepolymerization catalyst slurry, and the prepolymerization catalyst slurry is transported to a main reactor;

[0007] The temperature of the prepolymerized catalyst slurry transported to the main reactor is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

[0008] The second aspect of the present invention provides a polyolefin polymerization method, characterized in that the method comprises the following steps: merging the polyolefin catalyst composition with a transport medium to obtain a combined stream, and transporting the combined stream to a main reactor;

[0009] The temperature of the combined flow is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

[0010] The third aspect of the present invention provides a method for prepolymerization of the polyolefin catalyst and application of the polyolefin polymerization method in olefin polymerization.

[0011] Through the above technical scheme, the polyolefin catalyst prepolymerization method and its application and the polyolefin polymerization method and its application provided by the present invention achieve the following beneficial effects:

[0012] The polyolefin catalyst prepolymerization method or polyolefin polymerization method provided by the present invention can significantly improve the running stability of the device, reduce the risk of catalyst feed blockage, and has no significant effect on the final polymerization activity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of a first embodiment of olefin polymerization including a continuous prepolymerization reactor.

[0014] Figure 2 Schematic diagram of a second specific embodiment of olefin polymerization including a continuous prepolymerization reactor.

[0015] Figure 3 Schematic diagram of a third embodiment of olefin polymerization including a continuous prepolymerization reactor.

[0016] Figure 4 is a schematic diagram of a specific embodiment of olefin polymerization without a continuous prepolymerization reactor.

[0017] Description of Reference Numerals

[0018] 11. continuous prepolymerization reactor; 12. main reactor; 101. catalyst composition; 102. olefin monomer stream; 103. continuous prepolymerization catalyst slurry; 105. main reactor discharge pipe;

[0019] 21. continuous prepolymerization reactor; 22. main reactor; 201. catalyst composition; 202. first olefin monomer stream; 203. second stream; 204. combined stream; 205. main reactor outlet pipe;

[0020] 31. continuous prepolymerization reactor; 32. main reactor; 33. cooler; 301. catalyst composition; 302. olefin monomer feed stream; 303. coolant; 304. continuous prepolymerization catalyst slurry; 305. main reactor discharge pipe; 41. main reactor; 401. catalyst composition; 402. transport medium; 403. combined feed stream; 404. main reactor discharge pipe. DETAILED DESCRIPTION

[0021] 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.

[0022] In the present invention, the unit "ppm (wt)" means one part per million by mass, and the unit "ppm (v)" means one part per million by volume.

[0023] The first aspect of the present invention provides a method for prepolymerization of a polyolefin catalyst, characterized in that the method comprises: in a prepolymerization reactor, an olefin monomer is contacted with a polyolefin catalyst composition for a prepolymerization reaction to obtain a prepolymerization catalyst slurry, and the prepolymerization catalyst slurry is transported to a main reactor;

[0024] The temperature of the prepolymerized catalyst slurry transported to the main reactor is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

[0025] The prepolymerization of the present invention refers to the polymerization of a polyolefin catalyst composition with C 2 -C 12 One or more olefin monomers, preferably ethylene, propylene, butene-1, etc., are contacted in a prepolymerization vessel (even a pipeline) at a relatively low temperature to form a catalyst encapsulated with polyolefins.

[0026] In the present invention, by controlling the temperature of the prepolymerized catalyst slurry to the main reactor to ≤20°C and the flow rate to >0.1m / s, the running stability of the device can be significantly improved, the risk of catalyst feed blockage can be reduced, and the final polymerization activity of the catalyst has no significant effect.

[0027] Furthermore, controlling the temperature of the prepolymerized catalyst slurry delivered to the main reactor to be ≤0°C and the flow rate to be ≥0.5 m / s can further improve the operational stability of the device.

[0028] According to the present invention, the prepolymerization reaction is a continuous prepolymerization.

[0029] In the present invention, the continuous prepolymerization refers to the polyolefin catalyst, cocatalyst, C 2 -C 12 Olefin monomer, solvent and / or external electron donor (for Ziegler-Natta catalyst) are continuously introduced into the prepolymerization container, and the C 2 -C 12 The olefin monomer and / or solvent flow rate is controlled to achieve residence time, and then continuously introduced into the main reactor. Residence time refers to the average reaction time of the catalyst in the prepolymerization reactor, which is generally expressed by the ratio of the volume of the prepolymerization reactor to the volume flow rate of the slurry out of the prepolymerization reactor.

[0030] In one specific embodiment of the present invention, olefin monomers and / or solvents and a polyolefin catalyst composition comprising a polyolefin catalyst, a cocatalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) are continuously introduced into a prepolymerization reactor, and in the prepolymerization reactor, they are contacted to carry out a prepolymerization reaction to obtain a prepolymerization catalyst slurry, and the prepolymerization catalyst slurry is transported to a main reactor;

[0031] The temperature of the prepolymerization catalyst slurry transported to the main reactor is controlled to be ≤20°C, preferably ≤0°C, and the flow rate is >0.1m / s, preferably ≥0.5m / s. The prepolymerization conditions of the continuous prepolymerization include: a residence time of 1-90min, preferably 5-70min, more preferably 10-60min; a prepolymerization temperature of -50 to 20°C, preferably -35 to 0°C; and a prepolymerization pressure of 0.1-10MPaG, preferably 0.5-6MPaG.

[0032] like Figure 1 As shown, in a specific embodiment of the present invention, an olefin monomer stream 102 comprising an olefin monomer and / or a solvent and a polyolefin catalyst composition 101 comprising a polyolefin catalyst, a co-catalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) are continuously introduced into a prepolymerization reactor 11, and in the prepolymerization reactor 11, they are contacted to carry out a first prepolymerization reaction to obtain a first prepolymerization catalyst slurry 103, and the first prepolymerization catalyst slurry 103 is transported to a main reactor 12 to carry out an olefin polymerization reaction, and the obtained polyolefin is discharged from the main reactor through a discharge pipe 105 of the main reactor; the temperature of the prepolymerization catalyst slurry 103 transported to the main reactor is controlled to be ≤20°C, preferably ≤0°C, and the flow rate is >0.1m / s, preferably ≥0.5m / s.

[0033] Wherein, the first prepolymerization conditions include: residence time of 1-90 min, preferably 5-70 min, more preferably 10-60 min; prepolymerization temperature of -50 to 20°C, preferably -35 to 0°C; prepolymerization pressure of 0.1-10 MPaG, preferably 0.5-6 MPaG.

[0034] In a specific embodiment of the present invention, the method comprises:

[0035] S1. In a prepolymerization reactor at a temperature below 50° C., contacting a first olefin monomer stream comprising an olefin monomer and / or a solvent with a polyolefin catalyst composition to carry out a second prepolymerization reaction to obtain a second prepolymerization catalyst slurry;

[0036] S2, the second prepolymerization catalyst slurry is merged with a second stream containing olefin monomers and / or solvent to obtain a merged stream, and the merged stream is transported to a main reactor;

[0037] The temperature of the combined stream transported to the main reactor is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

[0038] According to the present invention, the mass ratio of the first olefin monomer stream to the second stream is 5:95-95:5; preferably 15:85-85:15.

[0039] According to the present invention, the conditions of the second prepolymerization reaction include: a residence time of 1-90 min, preferably 5-80 min, more preferably 5-50 min; a prepolymerization temperature of -50 to 50°C, preferably -10 to 50°C, more preferably 0-35°C; a prepolymerization pressure of 0.1-10 MPaG, preferably 0.5-6 MPaG.

[0040] According to the present invention, the temperature of the second stream is from -50 to 30°C, preferably from -40 to 0°C.

[0041] like Figure 2 As shown, in one specific embodiment of the present invention, a first olefin monomer stream 202 comprising an olefin monomer and / or a solvent and a polyolefin catalyst composition 201 comprising a polyolefin catalyst, a co-catalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) are continuously introduced into a prepolymerization reactor 21, and a second prepolymerization reaction is carried out in contact in the prepolymerization reactor 21 at a temperature below 50° C. to obtain a second prepolymerization catalyst slurry;

[0042] Wherein, the second prepolymerization conditions include: residence time of 1-90min, preferably 5-80min, more preferably 5-50min; prepolymerization temperature of -50 to 50°C, preferably -10 to 50°C, more preferably 0 to 35°C; prepolymerization pressure of 0.1-10MPaG, preferably 0.5-6MPaG.

[0043] The second prepolymerized catalyst slurry is combined with the second material stream 203 containing olefin monomers and / or solvent to obtain a combined material stream 204, and the combined material stream 204 is transported to the main reactor 22. After a polymerization reaction is carried out in the main reactor, the obtained polyolefin is discharged from the main reactor through the main reactor discharge pipe 205;

[0044] The temperature of the combined stream transported to the main reactor is controlled to be ≤20°C, preferably ≤0°C, and the flow rate is controlled to be >0.1 m / s, preferably ≥0.5 m / s.

[0045] In a specific embodiment of the present invention, the method comprises:

[0046] (a) in a continuous prepolymerization reactor at a temperature below 50° C., contacting an olefin monomer with a polyolefin catalyst composition to carry out a third prepolymerization reaction to obtain a third prepolymerization catalyst slurry;

[0047] (b) cooling the third prepolymerized catalyst slurry so that the temperature of the third prepolymerized catalyst slurry when it is transported to the main reactor is ≤20° C. and the flow rate is >0.1 m / s.

[0048] According to the present invention, the conditions of the third prepolymerization reaction include: a residence time of 1-90 min, preferably 5-80 min, more preferably 5-50 min; a prepolymerization temperature of -50 to 50°C, preferably -10 to 50°C, more preferably 0-35°C; a prepolymerization pressure of 0.1-10 MPaG, preferably 0.5-6 MPaG.

[0049] In the present invention, the cooling and temperature reduction can be carried out in a conventional cooler in the art, such as a shell-and-tube heat exchanger and / or a sleeve heat exchanger, preferably a jacketed tube cooler.

[0050] like Figure 3 As shown, in one specific embodiment of the present invention, olefin monomers and / or solvents 302 and a polyolefin catalyst composition 301 comprising a polyolefin catalyst, a co-catalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) are continuously introduced into a prepolymerization reactor 31, and a third prepolymerization reaction is carried out in the prepolymerization reactor 31 at a temperature below 50° C. to obtain a third prepolymerization catalyst slurry 303, and the third prepolymerization catalyst slurry is transported to a main reactor 32;

[0051] Wherein, the third prepolymerization conditions include: residence time of 1-90min, preferably 5-80min, more preferably 5-50min; prepolymerization temperature of -50 to 50°C, preferably -10 to 50°C, more preferably 0 to 35°C; prepolymerization pressure of 0.1-10MPaG, preferably 0.5-6MPaG.

[0052] The third prepolymerized catalyst slurry 303 is cooled in the cooler 33 so that the temperature of the third prepolymerized catalyst slurry when transported to the main reactor is ≤20°C, preferably ≤0°C, and the flow rate is >0.1 m / s, preferably ≥0.5 m / s.

[0053] According to the present invention, the prepolymerization ratio of the continuous prepolymerization is ≤1000 times, preferably 10-500 times.

[0054] In the present invention, the prepolymerization ratio refers to the mass ratio of the polymer generated during the prepolymerization process to the catalyst.

[0055] According to the present invention, the prepolymerization reaction is a batch prepolymerization.

[0056] In the present invention, the intermittent prepolymerization refers to a polyolefin catalyst, a co-catalyst, an inert solvent,2 -C 12 Olefin monomers and / or external electron donors (for Ziegler-Natta catalysts) are intermittently or partially intermittently introduced into the prepolymerization container, and the C 2 -C 12 The prepolymerization rate can be controlled by adjusting the amount of olefin added. The prepolymerized catalyst obtained by intermittent prepolymerization is stored in the prepolymerization container in the form of solvent slurry or solid. 2 -C 12 The olefin monomer, inert solvent, inert gas, etc. are continuously or intermittently introduced into the main reactor, wherein the main reactor can be at least one of a gas phase reactor, a liquid phase reactor and a multiphase reactor.

[0057] According to the present invention, the prepolymerization ratio of the intermittent prepolymerization is ≤500 times, preferably ≤100 times.

[0058] According to the present invention, the prepolymerization conditions of the intermittent prepolymerization include: the prepolymerization temperature is -30-120°C, preferably 0-60°C; the prepolymerization pressure is 0.1-10 MPaG, preferably 0.1-3 MPaG.

[0059] According to the present invention, the polyolefin catalyst composition comprises a polyolefin catalyst, a co-catalyst, optionally an impurity remover and optionally an external electron donor.

[0060] In the present invention, the polyolefin catalyst may be a conventional polyolefin catalyst in the art, for example, at least one selected from the group consisting of a Ziegler-Natta catalyst, a chromium oxide-based Philips catalyst, and a single-active-site metallocene catalyst.

[0061] In the present invention, the Ziegler-Natta type catalyst comprises:

[0062] (1) A compound of a transition metal of Groups 4 to 6, preferably of the formula Ti(OR) n-y X y Ti-haloalcoholate, wherein n is the valence of titanium, y is a number between 1 and n-1, X is a halogen, and R is a halogen having 1 to 10 carbon atoms, which may be TiCl 4 or TiCl 3 .

[0063] (2) The catalyst carrier is selected from Group 1 to Group 4 compounds, mainly silicon dioxide, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, magnesium chloride and the like, or a mixture thereof.

[0064] (3) A cocatalyst, also an impurity remover, optionally a Group 13 metal compound (preferably an aluminum compound). The aluminum compound may be suitably selected from an alkyl aluminum, an alkyl aluminum halide, an alkoxy aluminum, an alkyl alkoxy aluminum or an alkoxy aluminum halide compound.

[0065] (4) The solid catalyst component usually also contains an internal electron donor, such as alcohols, esters, ketones, amines, acyl, amines, nitriles, alkoxysilanes and aliphatic ethers. Suitable internal electron donors are preferably 1,3-diethers, (di)esters of aliphatic or aromatic (di)carboxylic acids, such as phthalates, maleates, substituted maleates (such as citraconates), benzoates, glutarates, cyclohexene-1,2-dicarboxylates and succinates or their derivatives and mixtures. These electron donor compounds can be used alone or in a mixture with other electron donor compounds.

[0066] In the present invention, the single-active-center metallocene catalyst comprises: a metallocene compound, a co-catalyst, a carrier, and the like.

[0067] (i) The metallocene catalyst comprises a metallocene compound having the following structure:

[0068] Unbridged Metallocene Compounds (Ar) 2 MQ 2 Formula 1

[0069] or bridged metallocene compound T(Ar) 2 MQ 2 Formula 2

[0070] wherein M is a transition metal selected from Groups 3 to 5 of the Periodic Table of Elements, preferably a transition metal of Group 4, most preferably zirconium, titanium, hafnium, or vanadium;

[0071] Q is a sigma ligand, preferably independently a hydrogen atom, a halogen atom, C 1 -C 6 Alkoxy atom group, C 1 -C 6 an alkyl, phenyl or benzyl group, and the hydrocarbon group may optionally contain one or more B, O, P, F, Cl, Si atoms;

[0072] Ar is independently selected from cyclopentadienyl, indenyl, tetrahydroindenyl and fluorenyl; and wherein Ar is optionally substituted by one or more substituents, each of which is independently a hydrogen atom or a hydrocarbon group, a substituted hydrocarbon group, a halogenated hydrocarbon group, a substituted halogenated hydrocarbon group, a silyl hydrocarbon group, a substituted silyl hydrocarbon group, a germyl hydrocarbon group, a substituted germyl hydrocarbon group substituent, wherein any one or two of the substituents may be joined together to form a ring structure; and the hydrocarbon group may optionally contain one or more B, O, P, F, Cl, Si atoms;

[0073] The T group is a divalent bridging group selected from -R' 2 C-, -R' 2 C-CR' 2 -、-R'2 Si-SiR' 2 -、-R' 2 Ge-divalent bridge, wherein R' is independently selected from hydrogen atoms, C 1 -C 20 Hydrocarbon, tri(C 1 -C 20 alkyl)silyl, tetra(C 1 -C 20 alkyl) silyl, penta(C 1 -C 20 alkyl) silyl, C 6 -C 20 Aryl, C 7 -C 20 Arylalkyl or C 7 -C 20 Alkylaryl. Preferred is -CH 2 -、-CH 2 CH 2 -、-C(CH 3 ) 2 -、-SiMe 2 -、-SiPh 2 -、-SiMePh-、-Si(CH 2 ) 3 -、-Si(CH 2 ) 4 -、-Si(Me 3 SiPh) 2 - or -Si(CH 2 ) 5 -, etc.; and the hydrocarbon group may optionally contain one or more B, O, P, F, Cl, Si atoms.

[0074] (ii) a cocatalyst for the above-mentioned metallocene catalyst, i.e. any compound capable of converting the catalyst precursor into an active polymerization catalyst, and preferably comprising an alkylaluminoxane compound (alumoxane) and / or a borate, specifically such as: methylaluminoxane MAO and / or tetrakis (perfluorinated aromatic) borates. Even more preferably, the cocatalyst comprises an anion selected from tetrakis (pentafluorophenyl) borate, tetrakis (perfluorobiphenyl) borate, tetrakis (perfluoronaphthyl) borate and combinations thereof. In the case of anionic cocatalysts, the cocatalyst also comprises a bulky organic cation (trialkylammonium, trialkylmethyl), preferably a dialkylanilinium cation, or a triphenylmethyl cation. Most preferably, the cocatalyst is an aluminoxane compound.

[0075] The cocatalyst can be injected directly into the prepolymerization reactor or the main reactor together with the catalyst, preferably on a metallocene compound supported on a solid support or self-supported.

[0076] (iii) The metallocene catalyst is a homogeneous catalyst or a heterogeneous catalyst, preferably a heterogeneous (supported) catalyst or a self-supported metallocene catalyst. The carrier for the heterogeneous (supported) catalyst is selected from silicon dioxide, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide and the like, or a mixture thereof.

[0077] According to the present invention, the olefin monomer, the first olefin monomer and the second olefin monomer are each independently C 2 -C 12 The olefin monomer is preferably at least one of ethylene, propylene and 1-butene.

[0078] In the present invention, the main reactor is selected from one or more reactor combinations (in parallel and / or in series) of a gas phase reactor, a liquid phase reactor, a solution reactor, and a multiphase reactor. The operating conditions of the main reactor are well known to those skilled in the art, and generally the operating temperature is ≥20°C and the operating pressure is ≥0.1MPaG.

[0079] In any embodiment, once the polyolefin prepolymerization catalyst slurry is transferred to the main reactor, it is mixed with C 2 -C 12 One or more of the olefins, preferably ethylene, propylene, 1-butene, are contacted in a reactor to form a polyolefin. The formed polyolefin includes polypropylene (homopolymer, random copolymer, block copolymer and / or impact copolymer), polyethylene (homopolymer, random copolymer, ethylene-propylene rubber, linear low density polyethylene, high density polyethylene and / or plastomer), and other C 4 -C 12 Polyolefins include polybutene, poly(butene-hexene), poly(ethylene-butene), poly(ethylene-hexene) and the like.

[0080] The second aspect of the present invention provides a polyolefin polymerization method, characterized in that the method comprises the following steps: merging a polyolefin catalyst composition or a prepolymerized catalyst with a transport medium to obtain a merged stream, and transporting the merged stream to a main reactor;

[0081] The temperature of the combined stream is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

[0082] According to the present invention, the temperature of the combined stream is controlled to be ≤0°C and the flow rate is controlled to be ≥0.5 m / s.

[0083] According to the present invention, the polyolefin catalyst composition comprises a polyolefin catalyst, a cocatalyst, optionally an impurity remover and optionally an external electron donor.

[0084] The composition or type of the polyolefin catalyst composition involved in the second aspect of the present invention is exactly the same as the composition or type of the olefin catalyst composition in the first aspect of the present invention. In order to avoid repetition, the present invention will not be described in detail in the second aspect, and those skilled in the art should not understand it as a limitation of the present invention.

[0085] According to the present invention, the prepolymerization catalyst is obtained by contacting an olefin monomer with a polyolefin catalyst composition to carry out a prepolymerization reaction. Preferably, the prepolymerization reaction is a batch prepolymerization.

[0086] Specifically, in one embodiment of the present invention, an olefin monomer stream comprising an olefin monomer and / or a solvent and a polyolefin catalyst composition comprising a polyolefin catalyst, a co-catalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) are introduced into a prepolymerization reactor for intermittent prepolymerization to obtain a prepolymerized catalyst, which is stored in the prepolymerization container in the form of a solvent slurry or a solid.

[0087] Wherein, the prepolymerization conditions of the intermittent prepolymerization include: the prepolymerization temperature is -30-120°C, preferably 0-60°C; the prepolymerization pressure is 0.1-10MPaG, preferably 0.1-3MPaG.

[0088] According to the present invention, the conveying medium is selected from C 2 -C 12 At least one of an olefin, a solvent and an inert gas.

[0089] like Figure 4 As shown, in one embodiment of the present invention, the 2 -C 12 A conveying medium 402 of at least one of olefin, solvent and inert gas is combined with a polyolefin catalyst composition 401 comprising a polyolefin catalyst, a co-catalyst and optionally an external electron donor (for a Ziegler-Natta catalyst) to obtain a combined stream 403, and the combined stream 403 is conveyed to a main reactor 41 to perform an olefin polymerization reaction, and the obtained olefin polymer is discharged from the main reactor through a discharge pipe 404 of the main reactor; wherein the temperature of the conveying medium 402 is ≤20°C, preferably ≤0°C;

[0090] The temperature of the combined material flow 403 is controlled to be ≤20°C, preferably ≤0°C, and the flow rate is controlled to be >0.1 m / s, preferably ≥0.5 m / s.

[0091] The third aspect of the present invention provides a method for prepolymerization of the polyolefin catalyst and application of the polyolefin polymerization method in olefin polymerization.

[0092] The present invention will be described in detail below through examples.

[0093] The propylene polymerization reaction was carried out in a 25 kg / hr bulk propylene polymerization unit, which mainly comprised a prepolymerization reactor (5 L) and a loop reactor (75 L).

[0094] The polymerization activity is obtained by calculating the mass ratio of olefin polymer to polyolefin catalyst per unit time.

[0095] Example 1

[0096] according to Figure 1 The process aggregation method and steps are as follows:

[0097] (1) Prepolymerization

[0098] The flow rate of the main catalyst (metallocene catalyst, prepared according to Example 1 of CN105622796B) is 0.42 g / hr, the flow rate of triisobutylaluminum (impurity remover) is 2.2 g / hr, and the flow rate of the liquid propylene stream 102 is 8 kg / hr. The polyolefin catalyst composition 101 containing the main catalyst and triisobutylaluminum and the liquid propylene stream 102 are continuously injected into the prepolymerization reactor 11. The prepolymerization temperature is -5°C, the prepolymerization pressure is 4.0 MPaG, and the catalyst residence time is about 21 min, to obtain a prepolymerization catalyst slurry 103.

[0099] The flow rate of the prepolymerized catalyst slurry 103 was about 0.34 m / s, and the temperature was -5°C.

[0100] (2) Propylene polymerization reaction in the main reactor

[0101] The prepolymerization catalyst slurry 103 is continuously injected into the loop reactor 12. The polymerization reaction temperature is 70°C, the reaction pressure is 4.0 MPaG, the total propylene feed (including liquid propylene feed stream 102) in the reactor is 55 kg / h, and hydrogen is added to the reactor. The calculated concentration of hydrogen in the reactor is 400 ppm (v).

[0102] Example 2

[0103] according to Figure 2 The process aggregation method and steps are as follows:

[0104] (1) Prepolymerization

[0105] The main catalyst (metallocene catalyst, prepared according to Example 1 of CN105622796B) has a flow rate of 0.42 g / hr, triisobutylaluminum (impurity remover) has a flow rate of 2.2 g / hr, and the first liquid phase propylene stream 202 has a flow rate of 8 kg / hr, which are continuously injected into the prepolymerization reactor 11. The prepolymerization temperature is 10°C, the prepolymerization pressure is 4.0 MPaG, and the catalyst residence time is about 20 min to obtain a prepolymerization catalyst slurry.

[0106] The flow rate of the second propylene stream 203 is 7 kg / hr, and the temperature is -20° C. The mass ratio of the first liquid phase propylene stream to the second propylene stream is 8:7.

[0107] The prepolymerized catalyst slurry is combined with the second liquid phase propylene stream to obtain a combined stream 204. The combined stream 204 is transported to the main reactor 21 at a flow rate of about 0.64 m / s and a temperature of about -4°C.

[0108] (2) Propylene polymerization reaction in the main reactor

[0109] Same as Example 1.

[0110] Example 3

[0111] Press Attach Figure 4 The process aggregation method and steps are as follows:

[0112] (1) Catalyst feed

[0113] The flow rate of the main catalyst (metallocene catalyst, prepared according to Example 1 of CN105622796B) is 0.42 g / hr, the flow rate of triisobutylaluminum (impurity remover) is 2.2 g / hr, the flow rate of liquid propylene 402 is 15 kg / hr, and the temperature is -6°C. The polyolefin catalyst composition 401 containing the main catalyst and triisobutylaluminum is merged with the liquid propylene 402 to obtain a merged stream 403, which is transported to the main reactor 42 for olefin polymerization reaction, and the obtained olefin polymer is discharged from the main reactor from the main reactor discharge pipe 404. The temperature of the merged stream 403 is controlled to be about -5°C, and the flow rate is about 0.64 m / s.

[0114] (2) Propylene polymerization reaction in the main reactor

[0115] Same as Example 1.

[0116] Example 4

[0117] Press Attach Figure 1 The process aggregation method and steps are as follows:

[0118] (1) Prepolymerization

[0119] The flow rate of the main catalyst (ZN catalyst, DQC401, produced by Sinopec Aoda Catalyst Branch) is 0.2g / hr, the flow rate of triethylaluminum (co-catalyst) is 2.1g / hr, the flow rate of the external electron donor (C-donor) is 0.3g / hr, and the flow rate of the liquid propylene stream 102 is 8kg / hr. The polyolefin catalyst composition 101 containing the main catalyst, triethylaluminum and the external electron donor and the liquid propylene stream 102 are continuously injected into the prepolymerization reactor 11. The prepolymerization temperature is -5°C, the prepolymerization pressure is 4.0MPaG, and the catalyst residence time is about 21min. The prepolymerization catalyst slurry 103 is obtained, and the prepolymerization catalyst slurry 103 is transported to the main reactor 12 for olefin polymerization.

[0120] The prepolymerized catalyst slurry 103 is transported to the main reactor at a flow rate of about 0.34 m / s and a temperature of -5°C.

[0121] (2) Propylene polymerization reaction in the main reactor

[0122] Same as Example 1.

[0123] Example 5

[0124] Press Attach Figure 3 The process aggregation method and steps are as follows:

[0125] (1) Catalyst feed

[0126] The main catalyst (metallocene catalyst, prepared according to Example 1 of CN105622796B) flow rate is 0.42 g / hr, the triisobutylaluminum (impurity remover) flow rate is 2.2 g / hr, and the liquid propylene (302) flow rate is 15 kg / hr. The main catalyst, triisobutylaluminum polyolefin catalyst composition 301 and liquid propylene stream 302 are continuously injected into the prepolymerization reactor 31 to obtain prepolymerization catalyst slurry 303. The prepolymerization temperature is 20°C, the prepolymerization pressure is 4 MPaG, and the catalyst residence time is about 11 min.

[0127] The prepolymerization catalyst slurry 303 is cooled to -5°C in the sleeve-type prepolymerization slurry cooler (33) under the action of the coolant 303, and then continuously introduced into the main reactor 32, wherein the flow rate of the cooled prepolymerization catalyst slurry to the main reactor is controlled to be about 0.64m / s.

[0128] (2) Propylene polymerization reaction in the main reactor

[0129] Same as Example 1.

[0130] Example 6

[0131] Press Attach Figure 4 The process aggregation method and steps are as follows:

[0132] (1) Prepolymerization

[0133] The prepolymerization is an intermittent prepolymerization. Specifically, 0.3 g of triisobutylaluminum (impurity remover) and 100 g of a main catalyst (metallocene catalyst, prepared according to Example 1 of CN105622796B) are injected into an intermittent prepolymerization reactor, and propylene is slowly introduced into the intermittent prepolymerization reactor. The prepolymerization temperature is 10° C., the prepolymerization pressure is 0.2 MPaG, and the prepolymerization ratio is 3 times.

[0134] The flow rate of the prepolymerization catalyst is 1.26 g / h, the flow rate of triisobutylaluminum (impurity remover) is 2.2 g / hr, the flow rate of liquid propylene 402 is 15 kg / hr, and the temperature is -6°C. The polyolefin catalyst composition 401 containing the main catalyst and triisobutylaluminum is merged with the liquid propylene 402 to obtain a merged stream 403, which is transported to the main reactor 42 for olefin polymerization reaction, and the obtained olefin polymer is discharged from the main reactor from the main reactor discharge pipe 404. The temperature of the merged stream 403 is controlled to be about -5°C, and the flow rate is about 0.64 m / s.

[0135] (2) Propylene polymerization reaction in the main reactor

[0136] Same as Example 1.

[0137] Comparative Example 1

[0138] The polymerization process conditions of this comparative example are the same as those of Example 1. The difference from Example 1 is that the temperature in the prepolymerization reactor is 30°C, the flow rate of the liquid propylene stream 102 is 7.2 kg / hr, the flow rate of the prepolymerization catalyst slurry 103 is about 0.34 m / s, and the temperature is 30°C.

[0139] Comparative Example 2

[0140] The polymerization process conditions of this comparative example are the same as those of Example 2. The difference from Example 2 is that the temperature in the prepolymerization reactor is 30°C, the temperature of the second propylene stream 203 is 30°C, and the flow rate is 5.3 kg / hr; the temperature of the combined stream 204 is about 30°C, and the flow rate is about 0.64 m / s.

[0141] Comparative Example 3

[0142] The polymerization process conditions of this comparative example are the same as those of Example 3. The difference from Example 3 is that the temperature of the transport medium liquid phase propylene 402 is 30°C, the flow rate is 13.3 kg / hr, the temperature of the combined stream 403 is about 30°C, and the flow rate is about 0.64 m / s.

[0143] Comparative Example 4

[0144] The polymerization process conditions of this comparative example are the same as those of Example 4. The difference from Example 4 is that the temperature in the prepolymerization reactor is 30°C, the flow rate of the liquid propylene stream 102 is 7.2 kg / hr; the temperature of the prepolymerization catalyst slurry 103 transported to the main reactor 12 is about 30°C, and the flow rate is about 0.34 m / s.

[0145] Comparative Example 5

[0146] The polymerization process conditions of this comparative example are the same as those of Example 1. The difference from Example 1 is that the flow rate of the liquid propylene stream 102 is 2.2 kg / hr; the flow rate of the prepolymerized catalyst slurry 103 is about 0.09 m / s, and the temperature is -5°C.

[0147] Table 1 Polymerization unit conditions and operating conditions

[0148]

[0149]

[0150] Note: ① Pressure difference between propylene (into the delivery pipeline) pump and main reactor

[0151] Table 1 (continued)

[0152]

[0153] Note: ① Pressure difference between propylene (into the delivery pipeline) pump and main reactor

[0154] The experimental results show that by lowering the temperature of the pipeline from the polyolefin catalyst to the main reactor and maintaining a high flow rate in the pipeline from the catalyst to the main reactor, the operating stability of the device can be significantly improved, the risk of catalyst feed blockage can be reduced, and there is no significant effect on the final polymerization activity of the catalyst.

[0155] Specifically, when the temperature and flow rate in the pipeline from the polyolefin catalyst to the main reactor meet the requirements of Examples 1-6 of the present invention, relative to Comparative Examples 1-5, the pressure difference between the prepolymerization reactor or the transport medium (inlet catalyst to the main reactor pipeline) pump and the main reactor is reduced, thereby reducing the transport resistance, reducing the risk of clogging, and improving the stability of the device.

[0156] 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 prepolymerization of polyolefin catalysts, characterized in that: The method comprises: in a prepolymerization reactor, olefin monomers are contacted with a polyolefin catalyst composition to perform a prepolymerization reaction to obtain a prepolymerization catalyst slurry, and the prepolymerization catalyst slurry is transported to a main reactor; Control the temperature of the prepolymerized catalyst slurry delivered to the main reactor to be ≤20°C and the flow rate to be >0.1 m / s; Wherein, the polymerization reaction is a continuous prepolymerization, and the prepolymerization ratio of the continuous prepolymerization is ≤1000 times.

2. The method according to claim 1, wherein: The temperature of the prepolymerized catalyst slurry transported to the main reactor is controlled to be ≤0°C and the flow rate to be ≥0.5 m / s.

3. The method according to claim 1, wherein: The prepolymerization reaction is a continuous prepolymerization, wherein the prepolymerization conditions of the continuous prepolymerization include: a residence time of 1-90 min; a prepolymerization temperature of -50 to 20° C.; and a prepolymerization pressure of 0.1-10 MPaG.

4. The method according to claim 3, wherein: The prepolymerization conditions of the continuous prepolymerization include: residence time of 5-70 min; prepolymerization temperature of -35 to 0° C.; and prepolymerization pressure of 0.5-6 MPaG.

5. The method according to claim 1, wherein: The method comprises: S1. In a prepolymerization reactor at a temperature below 50° C., contacting a first olefin monomer stream comprising an olefin monomer and a solvent with a polyolefin catalyst composition to carry out a second prepolymerization reaction to obtain a second prepolymerization catalyst slurry; S2, the second prepolymerization catalyst slurry is merged with a second stream containing a second olefin monomer and / or a solvent to obtain a merged stream, and the merged stream is transported to a main reactor; The temperature of the combined stream transported to the main reactor is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

6. The method according to claim 5, wherein: The mass ratio of the first olefin monomer stream to the second stream is 5:95-95:

5.

7. The method according to claim 6, wherein: The mass ratio of the first olefin monomer stream to the second stream is 15:85-85:

15.

8. The method according to claim 5, wherein: The conditions of the second prepolymerization reaction include: residence time of 1-90 min; prepolymerization temperature of -50 to 50° C.; and prepolymerization pressure of 0.1-10 MPaG.

9. The method according to claim 8, wherein: The conditions of the second prepolymerization reaction include: residence time of 5-80 min; prepolymerization temperature of -10 to 50° C.; and prepolymerization pressure of 0.5-6 MPaG.

10. The method according to claim 5, wherein: The temperature of the second stream is from -50 to 30°C.

11. The method according to claim 10, wherein: The temperature of the second stream is from -40 to 0°C.

12. The method according to claim 1, wherein: The method comprises: (a) in a continuous prepolymerization reactor at a temperature below 50° C., contacting an olefin monomer with a polyolefin catalyst composition to carry out a third prepolymerization reaction to obtain a third prepolymerization catalyst slurry; (b) cooling the third prepolymerized catalyst slurry so that the temperature of the third prepolymerized catalyst slurry when it is transported to the main reactor is ≤20° C. and the flow rate is >0.1 m / s.

13. The method according to claim 12, wherein: The conditions of the third prepolymerization reaction include: residence time of 1-90 min; prepolymerization temperature of -50 to 50° C.; and prepolymerization pressure of 0.1-10 MPaG.

14. The method according to claim 12, wherein: The conditions of the third prepolymerization reaction include: residence time of 5-80 min; prepolymerization temperature of -10 to 50° C.; and prepolymerization pressure of 0.5-6 MPaG.

15. The method according to claim 1, wherein: The prepolymerization ratio of the continuous prepolymerization is 10-500 times.

16. The method according to any one of claims 1 to 15, wherein: The polyolefin catalyst composition comprises a polyolefin catalyst, a co-catalyst, an optional impurity remover and an optional external electron donor.

17. The method according to claim 16, wherein: The polyolefin catalyst is selected from at least one of a Ziegler-Natta catalyst, a chromium oxide-based Philips catalyst and a single-active-site metallocene catalyst.

18. The method according to claim 1 or 5, wherein: The olefin monomer, the first olefin monomer and the second olefin monomer are each independently C2-C 12 Olefin monomers.

19. The method according to claim 18, wherein: The olefin monomer, the first olefin monomer, and the second olefin monomer are each independently selected from at least one of ethylene, propylene, and 1-butene.

20. A polyolefin polymerization method, characterized in that: The method comprises the following steps: combining a polyolefin catalyst composition or a prepolymerized catalyst with a transport medium to obtain a combined stream, and transporting the combined stream to a main reactor; The temperature of the combined stream is controlled to be ≤20°C and the flow rate is controlled to be >0.1 m / s.

21. The polyolefin polymerization method according to claim 20, wherein: The temperature of the combined stream is controlled to be ≤0°C and the flow rate to be ≥0.5 m / s.

22. The polyolefin polymerization method according to claim 20, wherein: The polyolefin catalyst composition comprises a polyolefin catalyst, a cocatalyst, optionally an impurity remover and optionally an external electron donor.

23. The polyolefin polymerization method according to claim 20, wherein: The prepolymerization catalyst is obtained by contacting an olefin monomer with a polyolefin catalyst composition to carry out a prepolymerization reaction.

24. The polyolefin polymerization method according to claim 20, wherein: The conveying medium is selected from C2-C 12 At least one of an olefin, a solvent and an inert gas.

25. The polyolefin polymerization method according to claim 20, wherein: The temperature of the conveying medium is ≤20°C.

26. The polyolefin polymerization method according to claim 25, wherein The temperature of the conveying medium is ≤ 0°C.

27. Use of the method for prepolymerization of a polyolefin catalyst according to any one of claims 1 to 19 or the method for polymerization of a polyolefin according to any one of claims 20 to 26 in olefin polymerization.

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