Process for producing catalyst for polyolefin synthesis

Abstract

The invention relates to a process comprising the steps of: (a) supplying reactants to a reactor vessel (A); (b) optionally, supplying a solvent to the reactor vessel; (c) subjecting the contents of the reactor vessel to reaction conditions to obtain a product mixture (1) comprising reaction products; (d) removing the product mixture (1) from the reactor vessel and feeding it to a decanter system (B); (e) separating the reaction product from the product mixture in a decanter system by decanting and removing a stream (2) comprising the reaction product; (f) removing the solvent-containing stream (3) from the decanter system; wherein at least one of the reactants supplied in step (a) is supplied in a form dissolved in a solvent, or a solvent is supplied in step (b). Such a process allows the production of catalyst systems with a low average particle size such as 2-4 [mu] m, with high purity, with high program efficiency.

Description

Technical Field

[0001] The present invention relates to a process for producing catalyst materials, in particular to a process for producing catalysts for the synthesis of polyolefins such as polyethylene. The process according to the invention allows the production of catalyst materials having a particularly desirable small average particle size at desirably high production rates. Background Art

[0002] Polyolefins are the most commonly used thermoplastic polymer materials in the world. They are suitable for manufacturing a large number of applications through conveniently operable manufacturing methods with desirable process economies.

[0003] Within the polyolefin genus, a variety of polymeric materials have been developed since the initial conception of the material family. In this group, many species are typically produced by catalytic processes. The continued development of the catalyst field for polyolefin synthesis has led to the development of a wide variety of grades of polyolefins, and continues to do so.

[0004] Special efforts in the field of synthesis of catalyst materials for the manufacture of polyolefin materials are to have available granular catalyst materials, which show appropriate catalytic activity, allowing the desired polyolefin materials to be synthesized with desired process economy, wherein the granular catalyst materials have a low average particle size. Especially for the manufacture of polyolefin materials with high molecular weight types, such as ultra-high molecular weight polyethylene materials (UHMWPE) types, in order to produce high-quality materials with high productivity, it is necessary to have a low average particle size in the catalyst materials used in such a manufacturing method. As used in the context of the present invention, UHMWPE can be understood to be related to polyethylene homopolymers or copolymers with a molecular weight of ≥1,000,000g / mol. UHMWPE can be, for example, a copolymer of ethylene and 1-butene, 1-hexene or 1-octene. The molecular weight of UHMWPE can be, for example, by the method of applying ASTM D4020-11, based on measuring intrinsic viscosity, measured via the method described herein. Summary of the invention

[0005] To achieve this object, it has now been found that this can be achieved by a method comprising the following steps:

[0006] (a) supplying reactants to a reactor vessel (A);

[0007] (b) optionally, supplying a solvent to the reactor vessel;

[0008] (c) subjecting the contents of the reactor vessel to reaction conditions to obtain a product mixture (1) comprising a reaction product;

[0009] (d) removing the product mixture (1) from the reactor vessel and supplying it to a decanter system (B);

[0010] (e) separating the reaction product from the product mixture in a decanter system by decanting and removing a stream (2) comprising the reaction product;

[0011] (f) removing the solvent-containing stream (3) from the decanter system;

[0012] At least one of the reactants supplied in step (a) is supplied in a form dissolved in a solvent, or a solvent is supplied in step (b).

[0013] Such a process allows the production of catalyst systems with low average particle sizes, such as 2-4 μm, with high purity at high process efficiency.

[0014] Stream (3) can be recycled via step (b) back to the reaction vessel.

[0015] The reactants supplied to the reactor vessel in step (a) may, for example, include:

[0016] (i) Formula MgR 2 A magnesium-containing compound wherein R is Cl, Br, I, F or a structural moiety selected from methoxy, ethoxy, n-propoxy or isopropoxy;

[0017] and / or

[0018] (ii) Formula TiO x (OR) 4-2x A titanium-containing compound wherein x is 0 or 1, and R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl;

[0019] and / or

[0020] (iii) having the formula MR n X 3-n A metal-containing compound, wherein

[0021] M is a metal selected from CAS IIIA group elements, preferably selected from aluminum and boron;

[0022] R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl;

[0023] n is an integer selected from 0, 1 or 2; and

[0024] X is a halogen atom, preferably selected from chlorine and bromine;

[0025] and / or

[0026] (iv) Formula R m SiCl 4-m Silicon-containing compounds, wherein

[0027] R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl; and

[0028] m is an integer selected from 0, 1 or 2;

[0029] and / or

[0030] (v) Optionally, AlR 3 An organoaluminum compound wherein R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl.

[0031] The magnesium-containing compound (i) may, for example, be selected from magnesium methoxide, magnesium ethoxide, magnesium isopropoxide, ethylethoxide, magnesium dichloride and magnesium dibromide. Preferably, the magnesium-containing compound (i) is magnesium ethoxide.

[0032] The titanium compound (ii) may be selected from tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetraisobutyl titanate, tetra-n-butyl titanate and tetra-n-octyl titanate. Preferably, the titanium compound (ii) is tetraisobutyl titanate or tetra-n-butyl titanate.

[0033] The metal-containing compound (iii) can be, for example, selected from aluminum trichloride, ethylaluminum dibromide, ethylaluminum dichloride, propylaluminum dichloride, n-butylaluminum dichloride, isobutylaluminum dichloride, diethylaluminum chloride and diisobutylaluminum chloride. Preferably, the metal-containing compound (iii) is selected from ethylaluminum dichloride, diethylaluminum chloride and diisobutylaluminum chloride. More preferably, the metal-containing compound (iii) is ethylaluminum dichloride.

[0034] The silicon-containing compound (iv) can be, for example, selected from silicon tetrachloride, methyltrichlorosilane, ethyltrichlorosilane, n-propyltrichlorosilane, isopropyltrichlorosilane, n-butyltrichlorosilane, isobutyltrichlorosilane, n-pentyltrichlorosilane, n-hexyltrichlorosilane, n-octyltrichlorosilane, isooctyltrichlorosilane, vinyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, isobutylmethyldichlorosilane, diisopropyldichlorosilane, diisobutyldichlorosilane, isobutylisopropyldichlorosilane, dicyclopentyldichlorosilane, cyclohexylmethyldichlorosilane, phenylmethyldichlorosilane, diphenyldichlorosilane, trimethylchlorosilane and triethylchlorosilane. Preferably, the silicon-containing compound (iv) is silicon tetrachloride.

[0035] The organoaluminium compound (v) may, for example, be selected from triethylaluminium, triisobutylaluminium, tri-n-hexylaluminium and trioctylaluminium. Preferably, the organoaluminium compound (v) is triisobutylaluminium.

[0036] For example,

[0037] The magnesium-containing compound (i) may be magnesium ethoxide;

[0038] The titanium-containing compound (ii) may be isobutyl titanate or tetra-n-butyl titanate;

[0039] ● The metal-containing compound (iii) may be ethylaluminium dichloride; and

[0040] The silicon-containing compound (iv) may be silicon tetrachloride.

[0041] Step (c) can be carried out, for example, at a temperature of ≥50°C and ≤70°C, preferably ≥55°C and ≤65°C. Step (c) can be carried out, for example, at a pressure of ≥100 and ≤1,000kPa, preferably ≥150 and ≤500kPa. Step (c) can be carried out, for example, during a reaction duration of ≤5 hours, preferably ≥1 and ≤3 hours. Step (c) can be carried out, for example, at a temperature of ≥50°C and ≤70°C, at a pressure of ≥100 and ≤1,000kPa. Preferably, step (c) can be carried out, for example, at a temperature of ≥50°C and ≤70°C, at a pressure of ≥100 and ≤1,000kPa, during a reaction duration of ≤5 hours. More preferably, step (c) can be carried out, for example, at a temperature of ≥55°C and ≤65°C, at a pressure of ≥150 and ≤500kPa, during a reaction duration of ≥1 and ≤3 hours.

[0042] The solvent may be, for example, an organic solvent, preferably C 4 -C 20 The non-polar hydrocarbon is more preferably a compound selected from isobutane, isopentane, hexane, cyclohexane, heptane, methylcyclohexane, n-octane, isooctane, toluene, xylene, ethylbenzene, isopropylbenzene, ethyltoluene, n-propylbenzene and diethylbenzene. It is particularly preferred that the solvent is hexane.

[0043] The contents of the reactor in step (c) may, for example, contain ≥2.0 wt. % and ≤20.0 wt. %, preferably ≥2.0 wt. % and ≤10.0 wt. % of reactants relative to the total weight of the reactor contents. Steps (a)-(d) may be carried out in a batch process. Steps (e)-(f) may be carried out in a continuous operation.

[0044] The reactor vessel can be, for example, a stirred tank reactor equipped with a stirring system (C), preferably wherein the stirring system provides a mixing power density of ≥15.0 W / kg, preferably ≥25.0 and ≤75.0 W / kg. The application of such a mixing power density can be understood as contributing to the desired fine particle size of the catalyst produced according to the method, which in turn is beneficial during the polymerization of the polyolefin product using the catalyst, for example in the polymerization of ethylene to achieve improved heat and mass transfer, and can lead to achieving a higher polymerization reaction rate. In addition, the application of such a high mixing power is not only believed to allow the production of catalyst particles with such a fine particle size, but is also believed to contribute to a uniform distribution of particle size, i.e., reducing the formation of excessive fines and oversized particles.

[0045] The stirring system may for example comprise a pitched blade turbine, preferably wherein the pitch angle of the impeller blades of the turbine is ≥10° and ≤60°. Such a pitched blade turbine may for example comprise 1, 2 or 3 impellers (D), wherein, in the case where the turbine comprises 2 or 3 impellers, the spacing between the impellers is ≥0.5·D imp and ≤1.2·D imp , where D imp is the diameter of the impeller.

[0046] The tank reactor may include evenly distributed vertical baffles (E) at a distance between 0.05·D r With 0.1·D r extends inwardly into the reactor, where D r is the inner diameter of the tank reactor, and preferably the tank reactor comprises 3 to 6 baffles.

[0047] The reactor can be operated in such a way that, for example, the topmost impeller of the stirring system is immersed in the contents of the reactor vessel to at least 0.3·D imp Depth (F), where D imp is the diameter of the impeller. Operating the reactor at such content levels is believed to facilitate uniform flow patterns throughout the reaction mixture during the catalyst synthesis process, and thus may facilitate the production of a well-balanced number of catalyst particles having similar composition and morphology.

[0048] The turbine may include one or more impellers, each having a value ≥ 0.4·D r Diameter D imp , where D r is the inner diameter of the tank reactor, preferably wherein D imp ≥0.5·D r and ≤0.75·D r .

[0049] The average particle size D of the catalyst particles present in stream (2) 50 For example, it may be ≤4.0 μm, preferably ≥2.0 and ≤4.0 μm.

[0050] exist Figure 1 A non-limiting diagram of an embodiment of a reactor that can be used in the process of the present invention is shown in FIG. 1 , wherein symbols are used to represent:

[0051] A Reactor vessel

[0052] C. Mixing system

[0053] D Impeller

[0054] E Bezel

[0055] F Impeller immersion depth

[0056] D r Reactor inner diameter

[0057] D imp` Impeller diameter

[0058] also, Figure 2 A schematic representation of a method layout which may be suitable for carrying out the method according to the invention is provided, wherein

[0059] A Reactor vessel

[0060] B Decanter vessel

[0061] 1 Product mixture

[0062] 2 Reaction product stream

[0063] 3 Solvents

[0064] 4 Reactants

[0065] 5 Solvent.

[0066] The invention will now be illustrated by the following non-limiting examples.

[0067] A reaction mixture of tetrabutoxytitanium, ethoxymagnesium, ethylaluminum dichloride and tetrachlorosilane is added to a stirred tank reactor in the form of a 5% by weight solution in hexane. The reaction mixture is subjected to reaction conditions of a temperature of 60° C. and a pressure of 200 kPa for a period of 2 hours. After this, the contents of the reactor are supplied to a decanter system, which includes multiple decantation steps. Decantation is performed at 50° C. to obtain a concentrated mother liquor catalyst solution of 30% by weight catalyst material (with an average particle size of 2-4 μm) in hexane. In the produced catalyst, the free ion Ti concentration is determined to be less than 5 ppm. During the decantation, the tank reactor can be used to produce subsequent batches of catalyst products, thereby contributing to improving the space-time yield of the method.

[0068] The process allows for the production of a high purity catalyst product having a low average particle size, while the process can be operated at a desired process efficiency.

Claims

1. A method for producing a catalyst, the method comprising the following steps: (a) supplying reactants to a reactor vessel (A); (b) optionally, supplying a solvent to the reactor vessel; (c) subjecting the contents of the reactor vessel to reaction conditions to obtain a product mixture (1) comprising a reaction product; (d) removing the product mixture (1) from the reactor vessel and supplying it to a decanter system (B); (e) separating the reaction product from the product mixture in the decanter system by decanting and removing a stream (2) comprising the reaction product; (f) removing a stream (3) comprising the solvent from the decanter system; At least one of the reactants supplied in step (a) is supplied in a form dissolved in a solvent, or a solvent is supplied in step (b).

2. The process according to claim 1, wherein the stream (3) is recycled back to the reaction vessel via step (b).

3. The method according to any one of claims 1-2, wherein the reactants supplied to the reactor vessel in step (a) include: (i) a magnesium-containing compound of the formula MgR2, wherein R is Cl, Br, I, F or a moiety selected from methoxy, ethoxy, n-propoxy or isopropoxy; and / or (ii) Formula TiO x (OR) 4-2x A titanium-containing compound wherein x is 0 or 1, and R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl; and / or (iii) having the formula MR n X 3-n A metal-containing compound, wherein M is a metal selected from CAS IIIA group elements, preferably selected from aluminum and boron; R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl; n is an integer selected from 0, 1 or 2; and X is a halogen atom, preferably selected from chlorine and bromine; and / or (iv) Formula R m SiCl 4-m Silicon-containing compounds, wherein R is a hydrocarbon moiety containing ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl; and m is an integer selected from 0, 1 or 2; and / or (v) Optionally, an organoaluminium compound of formula AlR3, wherein R is a hydrocarbon moiety comprising ≥1 and ≤10 carbon atoms, preferably a moiety selected from methyl, ethyl, propyl, n-butyl, isobutyl or n-hexyl.

4. The method according to any one of claims 1 to 3, wherein step (c) is performed as follows: ● at a temperature of ≥50°C and ≤70°C, preferably ≥55°C and ≤65°C; and / or ● at a pressure of ≥100 and ≤1,000 kPa, preferably ≥150 and ≤500 kPa; and / or • During a reaction time of ≤ 5 hours, preferably ≥ 1 and ≤ 3 hours.

5. The method according to any one of claims 1 to 4, wherein the solvent is an organic solvent, preferably C4-C 20 The non-polar hydrocarbon is more preferably a compound selected from the group consisting of isobutane, isopentane, hexane, cyclohexane, heptane, methylcyclohexane, n-octane, isooctane, toluene, xylene, ethylbenzene, isopropylbenzene, ethyltoluene, n-propylbenzene and diethylbenzene.

6. The process according to any one of claims 1 to 5, wherein the contents of the reactor in step (c) comprise ≥2.0 wt.-% and ≤20.0 wt.-%, preferably ≥2.0 wt.-% and ≤10.0 wt.-% of the reactant, relative to the total weight of the reactor contents.

7. The method according to any one of claims 1 to 6, wherein steps (a) to (d) are carried out as a batch process.

8. The method according to any one of claims 1 to 7, wherein steps (e) to (f) are performed as a continuous operation.

9. The process according to any one of claims 1 to 8, wherein the reactor vessel is a stirred tank reactor equipped with a stirring system (C), preferably wherein the stirring system provides a mixing power density of ≥ 15.0 W / kg, preferably ≥ 25.0 and ≤ 75.0 W / kg.

10. The method according to claim 9, wherein the stirring system comprises a pitched blade turbine, preferably wherein the pitch angle of the impeller blades of the turbine is ≥ 10° and ≤ 60°.

11. The method according to any one of claims 9-10, wherein the pitched blade turbine comprises 1, 2 or 3 impellers (D), wherein: In the case where the turbine comprises 2 or 3 impellers, the distance between the impellers is ≥ 0.5·D imp and ≤1.2·D imp , where D imp is the diameter of the impeller.

12. The process according to any one of claims 9 to 11, wherein the tank reactor comprises uniformly distributed vertical baffles (E) at a depth between 0.05·D r With 0.1·D r extends inwardly into the reactor, wherein D r is the inner diameter of the tank reactor, preferably wherein the tank reactor comprises 3 to 6 baffles.

13. The process according to any one of claims 9 to 12, wherein the reactor is operated in such a manner that the topmost impeller of the stirring system is immersed in the contents of the reactor vessel to at least 0.3·D imp Depth (F), where D imp is the diameter of the impeller.

14. The method according to any one of claims 9 to 13, wherein the turbine comprises one or more impellers, each impeller having a value of ≥ 0.4·D r Diameter D imp , where D r is the inner diameter of the tank reactor, preferably wherein D imp ≥0.5·D r and ≤0.75·D r .

15. The process according to any one of claims 1 to 14, wherein the average particle size D of the catalyst particles present in the stream (2) is 50 ≤4.0 μm, preferably ≥2.0 and ≤4.0 μm.

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