method

Abstract

The present invention relates to a method for producing a catalyst, in particular a catalyst suitable for the polymerization of olefins. [Solution] In particular, a method for preparing an α-olefin polymerization catalyst composition is provided, comprising: (1) reacting a silica support with a dialkyl magnesium compound of the formula RMgR1, where R and R1 are the same or different C2-C12 alkyl groups, to form a silica-supported organomagnesium composition; (2) reacting at least one magnesium halide with at least one organic oxygen-containing titanium compound to form an Mg-Ti liquid complex, and contacting the silica-supported organomagnesium composition of step (1) with the formed Mg-Ti liquid complex to form a modified supported organomagnesium composition; and (3) reacting the modified supported organomagnesium composition of step (2) with a titanium halide.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a catalyst, in particular a catalyst suitable for the polymerization of olefins. [Background technology]

[0002] Catalysts for the polymerization of olefins such as ethylene and propylene are well known in the art. One particular class of catalysts is Ziegler-Natta catalysts. The present invention relates to supported Ziegler-Natta catalysts useful for olefin polymerization, and more particularly to supported Ziegler-Natta catalysts useful for the gas phase and slurry polymerization of alpha-olefins.

[0003] Ziegler-Natta catalysts are well known and have been used since the early 1950s. They generally contain a transition metal compound, typically titanium, and a magnesium compound. They can be prepared on a support such as silica, which may be pretreated with an organosilicon compound.

[0004] For example, WO99 / 05187 describes a method for preparing a catalyst precursor, which comprises the following steps: (1) reacting a silica support material having 0.3 to 1.2 millimoles of OH groups per gram of silica with a dialkylmagnesium compound of the formula RMgR1, where R and R1 are the same or different C2 to C12 alkyl groups, in an amount of 0.5 to 1.5 millimoles of dialkylmagnesium per gram of silica to form a silica-supported organomagnesium composition; (2) reacting the silica-supported organomagnesium composition with a tetraalkylorthosilicate, wherein the alkyl group contains from 2 to 6 carbon atoms, in an amount of from 0.2 to 0.8 millimoles of tetraalkylorthosilicate per gram of silica; (3) contacting the product from step (2) with a titanium compound in an amount of 0.3 to 1.5 millimoles per gram of silica; The preparation method comprises treating either the product from step (1) or the product from step (2), or directly a silica support, with a compound of formula R n SiCl 4-n wherein each R is the same or different and is hydrogen or an alkyl group, and n is an integer from 0 to 3.

[0005] EP 0 522 651 A2 describes a method for preparing a solid component of a catalyst for the (co)polymerization of ethylene by first contacting a silica support with a solution of magnesium dialkyl or magnesium alkyl chloride and then impregnating the silica with a solution of magnesium chloride, titanium tetrachloride and titanium tetraalkoxide, wherein titanium tetrachloride and titanium tetraalkoxide of equal or nearly equal molecular weight are used and the molar ratio of magnesium chloride to titanium compound is 1 to 10. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides an improved method for preparing a catalyst, the catalyst so prepared, and a process for polymerizing olefin polymers, preferably polymers of ethylene, using the catalyst.

[0007] The catalyst is a very active catalyst when used in the polymerization of ethylene and produces polyethylene with a narrow particle size distribution. [Means for solving the problem]

[0008] Thus, in a first aspect, there is provided a method for preparing an α-olefin polymerization catalyst composition, the method comprising: (1) The silica support is treated with a compound of the formula RMgR1 (wherein R and R1 are the same or different C2 to C 12with a dialkyl magnesium compound of formula (I) wherein the alkyl group is an alkyl group to form a silica-supported organomagnesium composition; (2) reacting at least one magnesium halide with at least one organic oxygen-containing titanium compound to form a Mg-Ti liquid complex, and contacting a silica-supported organomagnesium composition with the formed Mg-Ti liquid complex; and (3) reacting the modified supported organomagnesium composition of step (2) with a titanium halide. DETAILED DESCRIPTION OF THE INVENTION

[0009] The process of the present invention is similar in some respects to the process of WO 99 / 05187, however, in the present process both titanium and magnesium are added in two separate steps and using two different compounds for each individual metal.

[0010] More specifically, in the method of the present invention, magnesium is added via a dialkylmagnesium compound of formula RMgR1 and in a separate step via an Mg-Ti liquid complex, while titanium is added via an Mg-Ti liquid complex and in a separate step via the addition of a titanium halide.

[0011] (It is known, for example, that titanium halides are added in several stages rather than all at once. However, in the present invention, titanium, like magnesium, is added using two different compounds.)

[0012] The method of the present invention can also be said to require three separate steps for the addition of Mg and Ti compounds. Thus, in the first step, a silica support is reacted with a dialkylmagnesium compound to form a silica-supported organomagnesium composition. This is therefore the first magnesium addition step. The second step requires contacting the silica-supported organomagnesium composition (i.e., the product of the first step) with an Mg-Ti liquid complex. This is therefore both the second magnesium addition step and the first titanium addition step. In the third step, the modified supported organomagnesium composition of the second step is reacted with a titanium halide. This is therefore the second titanium addition step.

[0013] The use of a separate step and an Mg-Ti liquid complex makes it possible to provide a catalyst that is highly active when used in the polymerization of ethylene and produces polyethylene with a narrow particle size distribution.

[0014] More specifically, in a first step, the method of the present invention comprises treating a silica support with a compound of formula RMgR1, where R and R1 are the same or different C2 to C 12 The method includes reacting a magnesium salt of the formula (I) with a dialkyl magnesium compound of the formula (II) (wherein the alkyl group is a methyl group) to form a silica-supported organomagnesium composition.

[0015] The silica support may be any suitable silica, and as used herein, the terms "silica" and "silica support" can be used interchangeably. The silica support is preferably spherical and / or spheroidal. For the purposes of the present invention and the appended claims, spheroidal morphology means a sphere-like shape but not perfectly round, and in particular an ellipsoidal shape generated by rotating one or more ellipses around one of their axes. Therefore, for the purposes of the present invention and the appended claims, "spheroidal and / or spheroidal morphology" means that the silica support exhibits a spherical and / or spheroidal shape. Such spherical and / or spheroidal morphology of the silica support is usually identified by taking a micrograph of the support, which is currently a method by which those skilled in the art can identify the presence of spherical and / or spheroidal particles.

[0016] The silica support typically comprises greater than 98% by weight silicon dioxide, preferably greater than 99% by weight silicon dioxide.

[0017] The silica support should preferably have a median particle size of 0.1 to 250 μm, preferably 5 to 200 μm, for example 10 to 150 μm, and most preferably 15 to 100 μm. International Standard ISO 13320:2009 ("Particle size analysis - Laser diffraction method") can be used to measure median particle size characteristics. Suitable instruments for measurement include laser diffraction systems from Malvern instruments, such as the Malvern Mastersizer S or Malvern Mastersizer 2000.

[0018] The silica support is preferably about 100 ml 2 / g, preferably about 200m 2 / g, most preferably above 250m 2 / g~500m 2The silica support should have a surface area of ​​about 0.3 to 5.0 ml / g, typically 0.5 to 3.0 ml / g. The silica support may be preferably porous and may have a pore volume of about 0.3 to 5.0 ml / g, typically 0.5 to 3.0 ml / g. Surface area and pore volume can be determined according to the BET volumetric method of British Standard BS 4359 / 1 (1984).

[0019] The silica support typically contains residual surface hydroxyls. Preferably, the silica exhibits a residual surface hydroxyl content of 0.6 to 2 mmol, preferably 1 to 1.6 mmol, per gram of silica. If necessary, the level of surface hydroxyl (OH) groups on the silica support can be reduced by thermal and / or chemical treatment prior to reaction with the dialkylmagnesium compound.

[0020] In one embodiment, the silica support may be dried prior to reaction with the dialkylmagnesium compound. For example, the silica may be heated to a temperature of at least 150°C for up to 24 hours, typically 200°C to 400°C (more preferably 200°C to 350°C) for about 2 to 20 hours, preferably 4 to 10 hours. The resulting support is free of adsorbed water and has a surface hydroxyl content of preferably about 0.6 to 2 mmol, more preferably 1 to 1.6 mmol, per gram of silica.

[0021] Many methods are known for determining the amount of hydroxyl groups in silica; for example, the method described by J.B. Peri and A.L. Hensley, Jr., J. Phys. Chem., 1968, 72(8), pp. 2926-2933, or by any of the methods disclosed in "The surface chemistry of amorphous silica / Zhuravlev model (Colloids and Surfaces. A: Physiochemical and Engineering Aspects 173 (2000) pp. 1-38)." For the purposes of the present invention, the amount of hydroxyl groups in silica can be measured according to the method described in WO 99 / 05187.

[0022] The silica support may be a commercially available silica. For example, one suitable commercially available silica is sold by Ecovyst under the trademark ES-70W. ES-70W silica has a D50 of 35-47 microns (D10 of 10.0 microns, D90 up to 85.0 microns), a pore volume (IPA) of 1.55-1.75 ml / g, and a surface area (5-point BET) of 260-330 m. 2 / g. Another silica suitable for use in the present invention is a commercially available silica sold by Grace under the trademark SYLOPOL™ 2408D. This is a white powder consisting of synthetic amorphous silica and exhibits the following specifications: nitrogen pore volume greater than 1.35 cc / g; 280-355 m 2 / g surface area (D10 of 10.0 microns and D90 up to 85.0 microns). Another suitable silica is ES757, also marketed by Ecovyst. It has a D50 of 22-28 microns, a D90 of 260-330 microns. 2 / g surface area and pore volume of 1.55 to 2.00 mL / g.

[0023] Silica supports can be prepared by spray drying washed and aged hydrogel particles or spray hardening of hydrosols. Such methods are well known in the art and typically result in spherical and / or spheroidal particles. The particle size can be adjusted by selecting conditions. The resulting spherical and / or spheroidal particles can be further classified, for example, by sieving to adjust the median particle diameter and reduce the amount of fine and / or coarse particles. Although handling of the particles may result in some degree of breakage, the particles are preferably not subjected to any intentional crushing method. Preferably, spherical and / or spheroidal particles are prepared by spray hardening of hydrosols, preferably silica hydrosols. The resulting spherical and / or spheroidal hydrogel particles are appropriately subjected to a washing and aging process before water removal to generate an appropriate surface area and pore volume.

[0024] The dialkylmagnesium compound according to the present invention has the empirical formula RMgR1, where R and R1 are the same or different C2-C12 alkyl groups. Preferably, R and R1 are C2-C10 alkyl groups, for example, C4-C10 alkyl groups, more preferably C2-C8 alkyl groups, for example, C4-C8 alkyl groups. Butylethylmagnesium, butyloctylmagnesium and dibutylmagnesium are preferably used according to the present invention, with dibutylmagnesium being most preferred. Dibutylmagnesium may be, for example, n-butyl-s-butylmagnesium.

[0025] The contacting of silica with the dialkylmagnesium can be by any suitable method. In a preferred method, the silica support material is slurried in a non-polar solvent and the resulting slurry is contacted with the dialkylmagnesium, typically at a temperature ranging from about 25°C to about 100°C, preferably from about 40°C to about 60°C. A slurry of silica support material in a solvent can be prepared by introducing the support into the solvent, preferably with stirring, and heating the mixture to about 25°C to about 100°C, preferably from about 40°C to about 60°C, and then contacting with the dialkylmagnesium while continuing heating at the aforementioned temperature.

[0026] Suitable non-polar solvents are those materials in which all of the reactants used herein are at least partially soluble, e.g., dialkyl magnesium, titanium compounds are at least partially soluble, and which are liquid at the reaction temperature. Preferred non-polar solvents are alkanes such as isopentane, hexane, n-heptane, octane, nonane, and decane, although a variety of other materials can also be used, including cycloalkanes such as cyclohexane, and aromatic compounds such as benzene and ethylbenzene.

[0027] The most preferred non-polar solvent is hexane. Prior to use, the non-polar solvent should be purified, such as by percolation through silica gel and / or molecular sieves, to remove traces of water, oxygen, CO2, polar compounds, and other materials that may adversely affect catalytic activity.

[0028] In the most preferred embodiment, only the amount of dialkylmagnesium compound that will be deposited (physically or chemically) on the silica support is added, because any excess amount may react with other synthetic chemicals in a later step and precipitate outside the support. The exact molar ratio can be determined case by case, for example, by adding the dialkylmagnesium compound to a slurry of the silica support in a solvent while stirring the slurry, until the dialkylmagnesium compound is detected as a solution in the solvent.

[0029] It is also possible to add an amount of dialkylmagnesium compound in excess of that which will deposit on the support and then remove any excess dialkylmagnesium compound, for example by filtration and washing, although this alternative is less desirable.

[0030] Typically, the amount of dialkylmagnesium compound reacted with the silica support is 0.5 to 5 millimoles per gram of silica, more preferably 2 to 4 millimoles per gram of silica (i.e., equivalent to 0.5 to 5 millimoles Mg per gram of silica, more preferably 2 to 4 millimoles Mg per gram of silica).

[0031] In a preferred embodiment, the method comprises reacting a silica-supported organomagnesium composition with a silicon-containing compound, particularly a compound of the formula Si(OR) y (X) z (wherein X is a halogen, R is a C2-C6 alkyl, and y+z=4). Preferably, X is Cl. Suitable silicon-containing compounds include SiX4, preferably SiCl4, Si(OR)2(X)2, and Si(OR)4. Preferred compounds of formula Si(OR)2(X)2 are also chlorides, i.e., have the formula Si(OR)2(Cl)2. Typical examples are dimethoxydichlorosilane, diethoxydichlorosilane, diisopropoxydichlorosilane, dipropoxydichlorosilane, and dibutoxydichlorosilane. Diethoxydichlorosilane is most preferred.

[0032] Preferred compounds of formula Si(OR)4 that can be used include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrapropoxysilane, tetrabutoxysilane, with tetraethoxysilane being most preferred.

[0033] In such an embodiment, the method can include maintaining a slurry of a silica-supported organomagnesium composition obtained by reacting a silica support with a dialkylmagnesium at a temperature of 25°C to 100°C, preferably 40°C to 60°C, for the introduction of a silicon-containing compound.

[0034] Typically, the amount of silicon-containing compound added to the silica support is 0.5 to 5 millimoles per gram of silica, more preferably 2 to 4 millimoles per gram of silica.

[0035] Preferably, the amount of silicon-containing compound added is such that the molar ratio of the silicon-containing compound added to the dialkyl magnesium compound added in the previous step is about 0.2 to about 1.6, more preferably about 0.3 to about 1.5, and most preferably about 0.8 to about 1.2.

[0036] In step (2) of the present invention, the method comprises reacting at least one magnesium halide with at least one organic oxygen-containing titanium compound to form a Mg-Ti liquid complex, and contacting a silica-supported organomagnesium composition with the formed Mg-Ti liquid complex. It will be apparent that if the silica-supported organomagnesium composition has been reacted with a silicon-containing compound as described above, this step includes the silica-supported organomagnesium composition after it has reacted with the compound.

[0037] The magnesium halide can be any suitable magnesium halide. Preferably, it is magnesium chloride.

[0038] Regarding an organic oxygen-containing titanium compound (i.e., a titanium compound containing organic oxygen), the term "organic oxygen-containing compound" is understood to mean any compound in which an organic radical is bonded to titanium via oxygen, i.e., any compound containing at least one sequence of titanium-oxygen-organic radical bonds per titanium atom. The organic radical bonded to titanium via oxygen is generally selected from radicals containing up to 20 carbon atoms, and more particularly from those containing up to 10 carbon atoms. Good results are obtained when these radicals contain 2 to 6 carbon atoms. These radicals may be saturated or unsaturated and may have a branched, straight or cyclic chain. They are preferably selected from hydrocarbon-containing groups, especially alkyl (straight or branched), alkenyl, aryl, cycloalkyl, arylalkyl and acyl groups and their substituted derivatives.

[0039] The tetravalent titanium compounds are generally liquids and are generally soluble in any case, so they are preferably used.

[0040] The organic oxygen-containing titanium compound has the general formula TiO x (OR´) m-2x (where m is the valence of titanium, R´ represents the organic group defined above, and x is a number such that 0 < x ≦ (m - 1) / 2). Preferably, compounds in which 0 ≦ x ≦ (m - 2) / 2 are used. The organic oxygen-containing titanium compound can contain several different organic radicals.

[0041] Among the organic oxygen-containing compounds, mention may be made of alkoxides (such as Ti(O-n-C4H9)4), phenoxides (such as Ti(OC6H5)4), oxyalkoxides (such as TiO(OC2H5)2), condensed alkoxides (such as Ti2O(O-i-C3H7)6), carboxylates (such as Ti(OOCCH3)4) and enolates (such as titanium acetylacetonate).

[0042] Among all suitable titanium compounds, those containing only titanium-oxygen-organic radical bonds per titanium atom and no other bonds are preferably used. Alkoxides are very suitable. The best results are obtained with titanium tetraalkoxides, especially titanium tetrabutoxide.

[0043] The reaction of at least one magnesium halide with at least one organic oxygen-containing titanium compound can be carried out by any suitable known method, provided that it allows the formation of a complex in a liquid state. If the magnesium compound and / or titanium compound are liquid under the operating conditions of the reaction, it is desirable to carry out the reaction by simply mixing these reactants in the absence of a solvent or diluent. However, if the amount of liquid present in the reaction mixture is insufficient to complete the reaction, or if the two reactants are solid under the operating conditions of the reaction, the reaction can be carried out in the presence of a diluent.

[0044] The amount of titanium compound used in this step is usually defined relative to the amount of magnesium halide used. It can vary within a wide range. It is generally at least 0.06 moles of titanium present in the titanium compound per mole of magnesium present in the magnesium halide, in particular at least 0.6 moles (per mole Mg), with a value of at least 1.5 moles (per mole Mg) being preferred. The amount is usually up to 4 moles of titanium present in the titanium compound per mole of magnesium in the magnesium halide, more particularly up to 3 moles (per mole Mg), with a value of up to 2.5 moles (per mole Mg) being recommended.

[0045] The temperature at which the magnesium and titanium halide compounds are combined is generally below the decomposition temperature of the reactants and the liquid complex obtained after the reaction. It is generally at least -20°C, especially at least 0°C, with temperatures of at least 20°C being most common and temperatures of at least 100°C being preferred. The temperature is usually below 200°C, especially below 180°C, with temperatures of 140°C to 160°C being advantageous.

[0046] The duration of the reaction depends on the nature of the reactants and the operating conditions, and is advantageously long enough to cause a complete reaction between the reactants. The duration may generally vary from 10 minutes to 20 hours, more particularly from 1 to 15 hours, for example from 2 to 12 hours.

[0047] The pressure and the rate of addition of the reactants are not critical factors. For convenience, the reaction is generally carried out at atmospheric pressure, and the rate of addition is generally selected so as not to cause rapid heating of the reaction mixture due to possible self-acceleration of the reaction. The reaction mixture is generally stirred for the duration of the reaction to promote its homogenization. The reaction can be carried out continuously or batchwise. The reaction is preferably carried out between a pure magnesium halide compound and a titanium compound, i.e., in the absence of a diluent.

[0048] The formed Mg-Ti liquid complex can be used directly for the step of contacting a silica-supported organomagnesium composition with the Mg-Ti liquid complex. It can optionally and preferably be diluted in a diluent, preferably an inert diluent, before subsequent use. The diluent is generally selected from aliphatic or alicyclic hydrocarbons, preferably containing up to 20 carbon atoms, such as alkanes, such as isobutane, pentane, hexane, heptane, or cyclohexane, or mixtures thereof. Hexane is particularly well suited. It is also generally preferred that any such diluent used be the same as any diluent used in preparing the silica-supported organomagnesium composition. When diluted, the diluted Mg-Ti complex preferably contains 5 to 35 wt. % diluent and is preferably characterized by a viscosity of 4 to 120 mPa·s, more preferably 5 to 20 mPa·s, at 25°C.

[0049] The contacting of the silica-supported organomagnesium composition with the Mg-Ti liquid complex can be carried out in any suitable manner. This is usually carried out at a temperature of from -10°C, e.g., 0°C, to 150°C. The impregnation temperature is more preferably 15°C to 100°C. Reaction at the temperature used in step (1) is one preferred embodiment, but reaction at room temperature is also suitable. The Mg-Ti liquid complex may preferably be added while the supported organomagnesium mixture from the previous step is cooling, i.e., at a temperature between room temperature and the temperature of the previous step. The duration and pressure at which the impregnation is carried out are not essential parameters. The impregnation is generally carried out at atmospheric pressure, and good results are obtained if the duration of this impregnation is 2 to 4 hours to ensure satisfactory homogenization.

[0050] Typically, the Mg—Ti complex is used in this step in an amount such that 0.1 to 2 mmol of Mg—Ti complex is contacted with the silica-supported organomagnesium composition per gram of silica, e.g., 0.1 to 1.5 mmol of Mg—Ti complex is contacted with the silica-supported organomagnesium composition per gram of silica, which preferably corresponds to the use of complexes corresponding to at least 0.1 mmol and at most 2 mmol of magnesium per gram of silica and at least 0.2 mmol and at most 4 mmol of titanium per gram of silica, more preferably at least 0.1 mmol and at most 1.5 mmol of magnesium per gram of silica and at least 0.2 mmol and at most 3 mmol of titanium per gram of silica.

[0051] Typically, the amount of Mg-Ti liquid complex used is such that the amount of magnesium contacting the silica-supported organomagnesium composition in this step is 5-30% of the amount of magnesium / dialkylmagnesium compound contacting the silica support in the previous step.

[0052] This contacting results in a modified supported organomagnesium composition.

[0053] The amount of Mg-Ti liquid complex used is preferably selected so that the modified supported organomagnesium composition is: - at least 0.1 mmol and at most 2 mmol of magnesium per g of silica support, derived from the Mg-Ti liquid complex (i.e., without any magnesium already present); and - at least 0.2 mmol and at most 4 mmol titanium per g of silica support;

[0054] Typically, the amount of magnesium present in the modified supported organomagnesium composition after this step and originating from the Mg-Ti liquid complex addition is 5-30% relative to the amount of magnesium present in the catalyst after this step and originating from the dialkylmagnesium addition.

[0055] In step (3) of the method of the present invention, the modified supported organomagnesium composition from step (2) is reacted with a titanium halide.

[0056] In one embodiment, the modified supported organomagnesium composition from step (2) can be isolated by evaporation of any solvent present. Preferably, however, step (3) is carried out by adding titanium halide, optionally diluted in a diluent or solvent such as hexane, to a mixture of the modified supported organomagnesium composition, also present in a diluent or solvent (again, for example, hexane). Thus, in this case, the mixture obtained after adding the Mg-Ti liquid complex to the supported organomagnesium in step (2) can be used "as is," and the titanium halide (solution) is added.

[0057] Titanium chloride is preferred, and most preferably the titanium halide is titanium tetrachloride, although any suitable titanium halide can be used. The titanium halide can be added in a single addition or in multiple additions during this step.

[0058] This step is conveniently carried out at room temperature, although temperatures below room temperature, for example from 0°C, or above room temperature, for example up to 100°C, are not excluded. Duration and pressure are also not essential parameters. The reaction is generally carried out at atmospheric pressure, and good results are obtained if the impregnation time is between 6 and 24 hours. The mixture may be continuously or occasionally stirred or mixed during this period.

[0059] Typically, the amount of titanium used in this step is such that the amount of titanium in the Mg-Ti liquid complex contacted with the silica-supported organomagnesium composition in the previous step is 5-30% of the amount of titanium added in the titanium halide addition in this step.

[0060] (Or, stated another way, typically, the amount of titanium added as titanium halide in this step is 3.3 to 20 times the amount of titanium in the Mg-Ti liquid complex that was contacted with the silica-supported organomagnesium composition in the previous step.)

[0061] Typically, the amount of titanium halide used in this step is 2 to 15 moles, preferably 3 to 12 moles, and more preferably 4 to 9 moles per mole of Mg-Ti complex contacted with the silica-supported organomagnesium composition in step (2) of the process.

[0062] Typically, the amount of titanium halide used in this step is between 1 and 10 mmoles per gram of silica, more preferably between 2 and 7 mmoles per gram of silica.

[0063] Upon completion of the reaction, excess liquid is decanted off and the resulting solid is dried, for example, by application of a vacuum.

[0064] Preferably, the amount of magnesium in the resulting catalyst composition resulting from the Mg-Ti liquid complex addition is 5-30% of the amount of magnesium resulting from the dialkylmagnesium addition (this is the same ratio as in the modified supported organomagnesium composition described above).

[0065] Preferably, the amount of titanium in the resulting catalyst composition resulting from the Mg-Ti liquid composite addition is 5-30% relative to the amount of titanium resulting from the titanium halide addition.

[0066] Preferably, after addition of the titanium halide, a composition is obtained comprising: - silica, - 0.5 to 5 mmol of magnesium per gram of silica derived from a dialkylmagnesium compound of formula RMgR1, where R and R1 are the same or different C2 to C12 alkyl groups, - 0.1 mmol to 1 mmol of magnesium per gram of silica and 0.2 mmol to 2 mmol of titanium per gram of silica support, derived from an Mg-Ti liquid complex added to the support; - 1 to 10 mmol of titanium per gram of silica, derived from titanium halide.

[0067] The method of the present invention may further include adding one or more compounds capable of acting as an internal electron donor. Typically, if added, such compounds are added after step (3). Any suitable internal electron donor compound known in the art can be used. Typical known electron donors are oxygenated hydrocarbon compounds such as ethers, esters, alcohols, and ketones. The electron donor may be an aliphatic hydrocarbon, an aromatic hydrocarbon, a cyclic hydrocarbon, or a linear oxygenated hydrocarbon. The preferred internal electron donor in the present invention is an ether, and the use of an internal electron donor selected from tetrahydrofuran (THF), isoamyl ether (IAE), and bis-(4-chlorobutyl) ether (CBE) is particularly preferred.

[0068] In a second aspect, the present invention also provides a catalyst composition useful for olefin polymerization, the composition comprising: - silica, - 0.5 to 5 mmol of magnesium per gram of silica derived from a dialkylmagnesium compound of formula RMgR1, where R and R1 are the same or different C2 to C12 alkyl groups, - 0.1 mmol to 1 mmol of magnesium per gram of silica and 0.2 mmol to 2 mmol of titanium per gram of silica support from an Mg-Ti liquid complex added to the support, and - 1 to 10 mmol of titanium per gram of silica, derived from titanium halide.

[0069] In a third aspect, which is also a preferred embodiment of the second aspect, the present invention also provides a catalyst composition useful for olefin polymerization, the composition being obtainable by the process of the first aspect of the present invention.

[0070] The SiO2 content of the catalyst composition is generally not more than 70 wt. %, preferably greater than 40 wt. %, more preferably greater than 50 wt. %.

[0071] The total titanium content of the catalyst composition is 1 to 12 wt%, preferably 1 to 8 wt%, most preferably 3 to 7 wt%. Preferably, 50 to 95%, for example 70 to 90%, of the total amount of titanium is titanium derived from titanium halide.

[0072] The magnesium content of the catalyst composition is 0.5 to 6 wt %, preferably 2 to 5 wt %, and preferably 50 to 95%, for example 70 to 90%, of the total amount of magnesium is derived from the dialkyl magnesium.

[0073] The molar ratio of titanium to magnesium in the catalyst composition is preferably 0.3 to 3, more preferably 0.5 to 2.5, and most preferably 0.75 to 2.0.

[0074] The catalyst composition generally contains a halogen, typically chlorine. The halogen content of the catalyst composition is preferably 5 to 30% by weight, more preferably 10 to 25% by weight.

[0075] The catalysts according to the present invention are particularly suitable for the polymerization of olefins. The present invention also relates to the use of these catalysts in combination with a cocatalyst selected from organometallic compounds of metals from Groups 1, 2, 12, 13, and 14 in the polymerization of olefins. The organometallic compound functions as an activator of the catalyst and is commonly known as a "cocatalyst" and can be selected from organometallic compounds of lithium, magnesium, zinc, aluminum, or tin. The best results are obtained with organoaluminum compounds.

[0076] The organometallic compounds can be fully alkylated compounds with linear or branched alkyl chains containing up to 20 carbon atoms, such as n-butyllithium, diethylmagnesium, diethylzinc, tetraethyltin, tetrabutyltin, and trialkylaluminum. Alkylmetal hydrides with alkyl groups containing up to 20 carbon atoms, such as diisobutylaluminum hydride and trimethyltin hydride, can also be used. Alkylmetal halides with alkyl groups containing up to 20 carbon atoms, such as ethylaluminum sesquichloride, diethylaluminum chloride, and diisobutylaluminum chloride, are also suitable. Organoaluminum compounds obtained by reacting trialkylaluminum or dialkylaluminum hydrides (whose radicals contain up to 20 carbon atoms) with diolefins containing 4 to 20 carbon atoms, more specifically, the compound known as isoprenylaluminum, can also be used.

[0077] Trialkylaluminums are generally preferred, especially those having linear alkyl chains containing up to 18 carbon atoms, more especially 2 to 8 carbon atoms. Triethylaluminum and triisobutylaluminum are preferred.

[0078] The catalyst may be activated in situ by adding the cocatalyst and the prepared supported catalyst composition separately to the polymerization medium. Alternatively, the catalyst composition and cocatalyst can be combined prior to introduction into the polymerization medium, for example, at a temperature of from about -40°C to about 80°C for a period of up to about 2 hours.

[0079] Any suitable activating amount of cocatalyst can be used. The number of moles of cocatalyst per gram of titanium atoms in the catalyst can be, for example, from about 1 to about 100, and preferably greater than about 5.

[0080] In some embodiments, an "activity booster" can be added, which, as the name suggests, can provide increased activity. Suitable activity boosters include halogenated compounds, such as chlorinated or brominated compounds. One class of preferred activity boosters is halogenated hydrocarbons, where the hydrocarbon is an alkyl group containing 1 to 10, preferably 1 to 7, carbon atoms, or an aralkyl or aryl group containing 6 to 14, preferably 6 to 10, carbon atoms. Another class of preferred activity boosters is alkylaluminum halides, particularly when the alkyl group contains 1 to 7 carbon atoms. The most preferred activity boosters are chlorine-containing compounds. Examples include chloroform, methylene chloride, ethyl chloride, propyl chloride, butyl chloride, pentyl chloride, hexyl chloride, heptyl chloride, diethylaluminum chloride (DEAC), and cyclohexyl chloride (CyCl).

[0081] The catalysts described above can be used in any suitable polymerization process. In some embodiments, they can be used in a slurry phase process. Slurry processes typically use an inert hydrocarbon diluent and utilize temperatures from about 0°C to just below the temperature at which the resulting polymer is substantially soluble in the inert polymerization medium. Suitable diluents include toluene or alkanes such as hexane, propane, or isobutane. Preferred temperatures are from about 30°C to about 200°C, preferably from about 50°C to 125°C. Loop reactors are widely used in slurry polymerization processes. In loop reactors, the slurry is circulated within the reactor, typically by means of a pump or agitator. Liquid full loop reactors are particularly well known in the art and are described, for example, in U.S. Pat. Nos. 3,152,872, 3,242,150, and 4,613,484. Further references to slurry handling in which the present invention can be used to advantage are WO2007138257 and WO2006056763. Loop slurry polymerization is typically carried out at temperatures ranging from 50 to 125°C and pressures ranging from 1 to 100 bara. The product slurry, which contains polymer and diluent and in most cases also contains catalyst, olefin monomer, and comonomer, can be discharged intermittently or continuously.

[0082] The present invention is particularly useful in continuous gas phase processes for polymerization, such as those using a mixture of 0 to 60 mole percent hydrogen, 0 to 35 mole percent of one or more C groups at a pressure of 10 to 500 psi. 3-8 It can be carried out in the presence of the above catalyst and co-catalyst at a temperature of 50°C to 125°C, preferably below 115°C, using a reaction mixture containing an alpha-olefin, 15 to 100 mol% ethylene and 0 to 75 mol% inert gas such as N2.

[0083] Gas-phase polymerization of ethylene polymers, particularly fluidized-bed gas-phase polymerization, has been known for some time. An extensive general description of these types of processes can be found in the following article: "Gas Phase Ethylene Polymerization: Production Processes, Polymer Properties, and Reactor Modeling" by Tuyu Xie, Kim B. McAuley, James C.C.H.Su, and David W. Bacon. Ind. Eng. Chem. Res. 1994, 33, 449-479.

[0084] Generally, at least ethylene and optionally one or more C 3-8 A monomer feed containing α-olefins is fed into a gas-phase fluidized bed reactor or stirred-bed reactor. The monomer mixture, optionally together with hydrogen and / or an inert gas, is fed into the fluidized bed. In a fluidized-bed reactor, the gas velocity is sufficient to maintain the bed in a fluid flow of monomers and other components. In a stirred-bed reactor, mechanical agitation helps maintain the bed. Generally, fluidized-bed reactors are vertical, while stirred-bed reactors are horizontal. Cocatalyst and supported catalyst are fed into the bed simultaneously with the monomer. The monomer passing over the catalyst polymerizes on the catalyst and within the catalyst pores, increasing the particle size and breaking it down. The resulting polymer particles continue to grow while in the reactor. In a stirred-tank reactor, the bed is agitated into a discharge section and exits the reactor. In a fluidized-bed reactor, the reactor typically has a narrower section to maintain a high enough fluid (gas) velocity to fluidize the bed. There is an expansion zone at the top of the reactor which slows the velocity of the gas passing through the reactor and causes the polymer / catalyst particles to fall back into the bed. The discharge is from the bed zone in the reactor.

[0085] In both fluidized and stirred bed systems, the polymer particles removed from the reactor are degassed to remove any volatiles, and the resulting polymer (with entrained catalyst) may then be further processed (e.g., stabilizers may be added, if necessary, and pelletized).

[0086] In the reactor, the gas phase typically contains monomers, a balance gas such as nitrogen, a molecular weight control agent such as hydrogen, and optionally condensable liquids, depending on the process (e.g., U.S. Pat. No. 4,543,399, Jenkins III et al., disclosed September 24, 1985; U.S. Pat. No. 4,588,790, Jenkins III et al., issued May 15, 1986; and U.S. Pat. No. 5,352,749, DeChellis et al., disclosed October 4, 1994 to Exxon Chemical Patents; U.S. Pat. No. 5,436,304, issued July 25, 1995 to Exxon Chemical Patents). Further references for gas phase operations in which the present invention can be used to advantage are WO9428032, WO2010037650 and International Patent Application No. PCT / EP2011 / 070280.

[0087] The condensable liquid may be a condensable monomer used as a comonomer, such as but-1-ene, hex-1-ene, 4-methylpent-1-ene, cyclooctene, 1-pentene or octene, and / or any inert condensable liquid, such as an inert hydrocarbon, such as a C4-C8 alkane or cycloalkane, in particular butane, pentane or hexane. The partial pressure of said condensable liquid under the reaction conditions is preferably greater than 2 bar.

[0088] The present invention is advantageously used with very high space-time yields. The space-time yield ("STY") is [kg / (m 3 × h)] and represents the weight of polymer produced per unit of time and per unit of reactor volume. STY is 100 kg / (m 3 ×h) or more, and even 120kg / (m 3 ×h) or more is preferred.

[0089] The reactor mixture may comprise 0 to 60 mole % hydrogen, 0 to 35 mole % of one or more C 3-8 It contains an α-olefin, 15 to 100 mole percent ethylene, and 0 to 75 mole percent inert gas such as N2. Copolymerizable olefins include butene (1-butene), 4-methyl-1-pentene, pentene, hexene (1-hexene), and octene (1-octene), although it can be difficult to maintain significant amounts of octene in the gas phase. The polymer can have a density of 0.905 to 0.965 g / cc, typically about 0.910 to about 0.960 g / cc.

[0090] Fluidized bed gas phase reactors for producing polyethylene are generally operated at temperatures of from about 50°C to about 125°C (provided the sticking temperature of the polymer is not exceeded), preferably from about 75°C to about 110°C, and at pressures typically not exceeding 3,447 kPa (about 500 psi), preferably not exceeding about 2,414 kPa (about 350 psi).

[0091] Polymerization additives can also be advantageously added during the polymerization process according to the present invention. Activity-enhancing additives are preferred. For example, a halogenated hydrocarbon compound can be advantageously introduced during the polymerization in an amount effective to increase catalyst activity, preferably such that the molar ratio of the halogenated hydrocarbon compound to the amount of catalyst titanium introduced into the polymerization medium is greater than 0.001 and less than 10. The amount of halogenated hydrocarbon compound can also be advantageously controlled so that the molar ratio of halogenated hydrocarbon compound to cocatalyst is 0.03 to 0.2. The halogenated hydrocarbon compound can be a mono- or polyhalogenated saturated hydrocarbon, preferably selected from the group consisting of methylene chloride, chloroform, carbon tetrachloride, trichloro-1,1,1 ethane, and dichloro-1,2 ethane. Monoalkyl chlorides (R—Cl), such as butyl chloride, are preferred. Examples can be found in EP 0 703 246, WO 0 228 919, and EP 1 350 802.

[0092] Typically, the resulting polymer contains 85 to 100 wt. % ethylene and 0 to 15 wt. % of one or more C 3-8 The polymer must have a molecular weight (weight average, Mw) greater than 50,000 Da, including an α-olefin.

[0093] The resulting polymers can be used in many applications, such as film extrusion, both cast and blown film extrusion, and both injection and rotational molding applications. Typically, the polymers can be compounded with conventional additives, including heat and light stabilizers such as hindered phenols; UV stabilizers such as hindered amine light stabilizers (HALS); and processing aids such as fatty acids or their derivatives, optionally in combination with low molecular weight esters of polyethylene glycol, and fluoropolymers.

[0094] The invention will now be illustrated by the following non-limiting examples. [Example]

[0095] Example 1 Preparation of Mg-Ti composites Both (n-BuO)4Ti and MgCl2 were obtained from Merck. (n-BuO)4Ti was distilled to dryness at 250 °C, while MgCl2 was dried by heating to 250 °C under reduced pressure. A mixture of (n-BuO)4Ti (117.5 mmol) and anhydrous MgCl2 (58.5 mmol) was stirred at 155 °C for 12 h. The reaction mixture was allowed to cool to room temperature, and the product (a viscous oil) was decanted from the small amount of residual MgCl2. This product, {[(n-BuO)4Ti]2MgCl2}2, was used in the following synthesis without further purification.

[0096] Preparation of silica support ES757 silica, obtained from Ecovyst, was heated under nitrogen at a temperature of 200° C. for 5 hours. The resulting silica support had a surface hydroxyl content of 1.5 mmoles per gram of silica, as determined according to the method described in WO 99 / 05187.

[0097] Catalyst preparation 2 g of dried ES757 silica was placed in a Schlenk tube and reacted with 6.1 mmol of n-butyl-s-butyl-magnesium (equivalent to 3.05 mmol per g of silica) in hexane under nitrogen flow and shaking at 1500 rpm using an MX-S vortex mixer to form a silica-supported organomagnesium composition. The reaction was exothermic. The mixture was allowed to react for 30 minutes with regular shaking and heating to 50°C to evaporate the heptane.

[0098] Subsequently, 6.25 mmol of tetraethyl orthosilicate (tetraethoxysilane) in 15 ml of dry heptane was added, again with shaking, and the mixture was heated to 50° C. for 1 hour. The liquid was decanted and the solid was washed with dry heptane.

[0099] 1.25 g of the Mg-Ti complex prepared above was dissolved in dry heptane and added to the solid (corresponding to 1.61 mmol of Ti per g of support and 0.81 mmol of Mg per g of initial silica). The mixture was allowed to react for 30 minutes with regular shaking, after which the solvent was removed under reduced pressure.

[0100] The resulting solid was slurried in heptane, and 10 mmol of TiCl4 (equivalent to 5 mmol / g of initial silica) in heptane was added with regular shaking for 30 min at room temperature, after which the mixture was allowed to stand for 12 h. The liquid was decanted, and the solid was washed several times with dry heptane before being dried by heating at 50 °C.

[0101] The resulting catalyst contained 7.1 wt% titanium and 3.8 wt% magnesium.

[0102] polymerization Polymerization was carried out in a Fischer-Porter glass reactor using 10 mg of the above-prepared catalyst in 250 ml of heptane as diluent at a temperature of 75°C. The reaction gas mixture contained 3.85 bar of ethylene and 0.15 bar of hydrogen. 1 mmol of triethylaluminum was added as a cocatalyst. Polymerization was carried out for 50 minutes.

[0103] 28.5 g of polyethylene are obtained, which corresponds to a catalytic activity of 3450 g / g cat / h.

[0104] Example 2 The silica and catalyst preparation steps were the same as in Example 1, except that dichlorodiethoxysilane was used instead of tetraethyl orthosilicate during the preparation, and the addition was changed to add only 0.93 g of Mg-Ti complex and 3.8 mmol of TiCl. The resulting catalyst contained 3.9 wt% titanium and 4.7 wt% magnesium.

[0105] The polymerization was carried out in the same manner as in Example 1, except that 12 mg of catalyst was used and the polymerization time was 60 minutes. 39.5 g of polyethylene was obtained, which corresponds to a catalytic activity of 3292 g / g cat / h.

[0106] Example 3 The polymerization was carried out in the same manner as in Example 2, using the same catalyst as in Example 2, except that 14 mg of catalyst was used and 100 mg of cyclohexyl chloride was also added to the reactor. 71.6 g of polyethylene was obtained, corresponding to a catalyst activity of 5114 g / g cat / h.

[0107] Example 4 The silica and catalyst preparation steps were similar to those in Example 1, except that the silica used was ES70W and 5 mmol of TiCl was added instead of 10 mmol. As in Example 1, the silica was heated under nitrogen at a temperature of 200° C. for 5 hours. The resulting silica had a surface hydroxyl content of 1.6 mmol per gram of silica, measured according to the method described in WO 99 / 05187.

[0108] The resulting catalyst contained 6.1 wt% titanium and 4.1 wt% magnesium.

[0109] The polymerization was carried out in the same manner as in Example 1, except that 14 mg of catalyst was used and the reaction was carried out for 60 minutes. 55.1 g of polyethylene was obtained, which corresponds to a catalytic activity of 3957 g / g cat / h.

[0110] Comparative Example 1 A catalyst was prepared using ES70W silica according to the teachings of WO9905187 (i.e., the catalyst preparation included the addition of dialkylmagnesium, tetraethylorthosilicate, and titanium tetrachloride, but not the Mg-Ti complex). The resulting catalyst contained 3.4 wt% titanium and 1.7 wt% magnesium.

[0111] The polymerization was carried out as in Example 1, except that 11 mg of catalyst was used, 100 mg of cyclohexyl chloride was also added to the reactor, and the reaction was carried out for 60 minutes. 15.4 g of polyethylene was obtained, corresponding to a catalytic activity of 1400 g / g cat / h.

Claims

1. 1. A method for producing an alpha-olefin polymerization catalyst composition, comprising: (1) reacting a silica support with a dialkylmagnesium compound of formula RMgR1 to form a silica-supported organomagnesium composition, wherein R and R1 are the same or different C ２ ~C １２ is an alkyl group, (2) reacting at least one magnesium halide with at least one organic oxygen-containing titanium compound to form a Mg—Ti liquid complex, and contacting the silica-supported organomagnesium composition of step (1) with the formed Mg—Ti liquid complex to form a modified supported organomagnesium composition; and (3) reacting the modified supported organomagnesium composition of step (2) with a titanium halide; A method comprising:

2. The silica is spherical and / or spheroidal, has a median particle size of 5 to 200 μm and a surface roughness of 100 μm. ２ / g to 500m ２ 10. The method of claim 1, wherein the surface area of ​​the SiO2 nanoparticles is 100 / g.

3. 3. The method of claim 1 or 2, wherein the silica support has a residual surface hydroxyl content of 0.6 to 2 mmol / g of silica, preferably 1 to 1.6 mmol / g of silica, prior to reaction with the dialkylmagnesium.

4. 4. The method according to any one of claims 1 to 3, wherein the dialkyl magnesium is selected from butylethyl magnesium, butyloctyl magnesium and dibutyl magnesium, with dibutyl magnesium being most preferred.

5. 5. The method according to any one of claims 1 to 4, wherein the amount of dialkylmagnesium added to the silica support is from 0.5 to 5 millimoles per gram of silica, more preferably from 2 to 4 millimoles per gram of silica.

6. The silica-supported organomagnesium composition is prepared prior to step (2) by treating the silica-supported organomagnesium composition with a compound of the formula Si(OR) ｙ (X) ｚ wherein X is a halogen, R is a C2-C6 alkyl, and y+z=4.

7. 7. The method of claim 6, wherein the silicon-containing compound is added in an amount of 0.2 to 0.8 millimoles per gram of silica and / or in an amount such that the molar ratio of silicon-containing compound to magnesium in the silica-supported organomagnesium composition is from about 0.2 to about 1.

6.

8. 8. The method of any one of claims 1 to 7, wherein the Mg-Ti liquid composite is prepared by reacting magnesium chloride with the at least one organic oxygen-containing titanium compound.

9. 9. The method of any one of claims 1 to 8, wherein the organic oxygen-containing titanium compound comprises tetravalent titanium selected from alkoxides, phenoxides, oxyalkoxides, condensed alkoxides, carboxylates and enolates, preferably titanium tetraalkoxide.

10. 10. The method of any one of claims 1 to 9, wherein the amount of said organic oxygen-containing titanium compound corresponds to at least 0.6 moles and at most 4 moles of titanium per mole of magnesium in the magnesium halide.

11. 11. The method of any one of claims 1 to 10, wherein the amount of Mg-Ti liquid complex used in step (2) is such that in step (2) the silica-supported organomagnesium composition is contacted with: - at least 0.1 mmol and at most 2 mmol of magnesium per g of silica support, and - at least 0.2 mmol and at most 4 mmol titanium per g of silica support;

12. 12. The method according to any one of claims 1 to 11, wherein the titanium halide used in step (3) is titanium tetrachloride.

13. 13. The method according to any one of claims 1 to 12, wherein the amount of Mg-Ti liquid complex used in step (2) is such that the amount of magnesium contacting the silica-supported organomagnesium composition in step (2) is 5 to 30% of the amount of magnesium contacting the silica support in the addition of the dialkylmagnesium in step (1).

14. 14. The method of any one of claims 1 to 13, wherein the amount of titanium halide used in step (3) is an amount such that the amount of titanium used is 3.3 to 20 times the amount of titanium in the Mg-Ti liquid complex contacted with the silica-supported organomagnesium composition in step (2).

15. A catalyst composition useful for olefin polymerization, said composition comprising: - silica, - 0.5 to 5 mmol of magnesium per gram of silica derived from a dialkylmagnesium compound of formula RMgR1, where R and R1 are identical or different C2 to C12 alkyl groups; - 0.1 to 1 millimole of magnesium per gram of silica and 0.2 to 2 millimole of titanium per gram of silica support, derived from an Mg-Ti liquid complex added to said support; and 1 to 10 mmol of titanium per gram of silica, derived from titanium halide A catalyst composition comprising:

16. A catalyst composition useful for olefin polymerization, obtainable by the process of any one of claims 1 to 14.

17. 17. A process for polymerizing olefins, comprising polymerizing olefins in the presence of the catalyst composition of claim 15 or claim 16.

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