Olefin polymerization catalyst as well as preparation method and application thereof

Abstract

The invention relates to an olefin polymerization catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: (1) preparing a solid carrier of spherical particles through the reaction of a magnesium carbonate ethanol salt complex and an acidity-enhanced phenolic compound, and heating the obtained carrier in an inert diluent; (2) carrying out contact reaction on the solid carrier prepared in the step (1), a titanium compound Ti (OR1) nCl4-n, halogenated hydrocarbon and an internal electron donor to obtain a main catalyst of solid spherical particles; and (3) contacting the main catalyst with an organic aluminum compound cocatalyst and an external electron donor serving as a selectivity control agent to obtain the olefin polymerization catalyst. Compared with the prior art, the improved high-activity olefin polymerization catalyst is used for catalyzing polymerization production of low-carbon alpha-olefin, and a polyolefin product with good performance and relatively narrow particle size distribution is obtained.

Description

Technical Field

[0001] The present invention relates to a high-activity olefin polymerization catalyst and a method for preparing the same. More specifically, the present invention relates to an olefin polymerization catalyst containing magnesium and titanium components and a method for preparing the same, as well as a method for olefin polymerization using the catalyst. Background Art

[0002] The production of polymers and copolymers of low carbon alpha olefins, particularly ethylene and propylene, has acquired substantial commercial significance. The polymer products are relatively inexpensive and possess many commercially useful properties. In the case of ethylene polymerization, the process is relatively simple because the product type is not affected by the manner in which the ethylene molecules are incorporated into the growing polymer chain, and the products do not exist in stereoisomeric forms.

[0003] However, in the case of propylene polymerization, the presence of methyl side groups on the polymer chain leads to the possibility of several product types, depending on the stereoregularity of the addition of the propylene molecules to the growing chain. Most commercial polypropylene is crystalline and the propylene monomer molecules are added to the polymer backbone in a regular 1,2 insertion pattern to produce a stereoregular product. Whereas the polymer obtained by the addition of propylene units in a random and irregular manner is called atactic, this amorphous form is less desirable and, if the atactic polymer is present in a significant amount, it must be removed by an extraction step to provide a more desirable crystalline polymer.

[0004] Equally important from a commercial perspective is the activity of the polymerization catalyst. Many early polymerization catalysts, for example, trivalent titanium, chromium or vanadium catalysts have relatively low activity and the polymer product contains a significant proportion of catalyst residues. In order to obtain commercially acceptable performance, these residues need to be removed by a deashing step.

[0005] High-activity olefin polymerization catalysts have sufficient catalytic activity while ensuring high stereoregularity, so no extraction and / or deashing steps are required. Existing high-activity olefin polymerization catalysts are usually formed by a main catalyst containing magnesium, titanium and halogen moieties, a cocatalyst usually an organoaluminum compound, and an external electron donor that can serve as a stereoselectivity control agent. Although each of these components has a significant effect on the olefin polymerization process and the resulting polymer, the properties of the catalyst and the polymer product are affected by the specific properties of the main catalyst. Many studies aimed at improving olefin polymerization catalysts are devoted to improving the main catalyst.

[0006] US Pat. No. 5,200,200 and US Pat. No. 4,330,649 disclose a method for preparing a solid main catalyst component, wherein a soluble magnesium compound such as magnesium chloride is heated with a higher alcohol having more than 4 carbon atoms in the presence of an ester to obtain a solution, and the solution is added to titanium tetrachloride and an internal electron donor to obtain the main catalyst component. US Pat. No. 4,472,521 uses a magnesium alkoxide to react with an excess of titanium alkoxide having 4 or more carbon atoms in the presence of an aromatic hydrocarbon to obtain a solution, and then titanium tetrachloride and an internal electron donor are added to the solution to produce a solid main catalyst, which is then post-treated with a transition metal halide once or more times and used for olefin polymerization.

[0007] Adopting alkoxy magnesium as magnesium source to prepare olefin polymerization main catalyst has the advantages of short process flow, can obviously reduce the subsequent titanium tetrachloride usage, alleviate the advantages of waste liquid treatment pressure, and the main catalyst obtained has better molecular weight regulation ability, so it is an attractive technical solution. In practical applications, its alkoxy part generally has one or two carbon atoms and is most commonly used, such as ethoxy magnesium. And the use of ethoxy magnesium has also brought some unique problems, because unlike other alkoxy magnesium, ethoxy magnesium is not easily soluble in its corresponding alcohol, i.e. ethanol. U.S. Patent No. 4522588 has proposed various measures to dissolve alkoxy magnesium, including forming composite ethoxy magnesium. And US 4710428 has proposed the technical solution of dissolving ethoxy magnesium by reacting with carbon dioxide in ethanol in several disclosed methods. US 4540679 prepares the solid carrier of granular particles by contacting the suspension of ethoxy magnesium in ethanol with carbon dioxide, adding the hydrocarbon solution of organoaluminum compound in the obtained solution, and then preparing the olefin polymerization main catalyst component with titanium tetrachloride contact reaction. In US Pat. No. 4,728,705, ethoxymagnesium in ethanol is reacted with carbon dioxide to form a solution, which is then spray-dried to produce solid carrier particles for subsequent titanium compound impregnation reactions, thereby obtaining an olefin polymerization main catalyst with a relatively ideal morphology.

[0008] The reaction of magnesium ethoxide with carbon dioxide in ethanol produces a soluble complex containing magnesium, ethoxy and carbon dioxide moieties, commonly referred to as magnesium carbonate ethoxide (CMEO). The exact structure of the complex is currently unknown, but its stable form at atmospheric pressure can be represented by the following formula:

[0009] Mg 2 (OEt) 4 (CO 2 ) 3

[0010] The complex is soluble in ethanol. Although the above references disclose a method for preparing an olefin polymerization main catalyst using the carbon dioxide-containing complex and applying it to olefin polymerization, there are generally disadvantages such as low polymerization activity, low polymer bulk density, and insufficient particle distribution. Summary of the invention

[0011] The purpose of the present invention is to provide an olefin polymerization catalyst and its preparation method and application in order to overcome the defects of the above-mentioned prior art. The catalyst is used to polymerize low-carbon α-olefins, and the polymerization activity is high. The obtained polymer product has a high bulk density and a relatively narrow particle size distribution. Compared with the prior art, it can operate more stably and efficiently on a large-scale olefin polymerization process device.

[0012] The object of the present invention can be achieved by the following technical scheme: A method for preparing an olefin polymerization catalyst comprises the following steps:

[0013] (1) preparing a solid support of spherical particles by reacting a magnesium carbonate ethanolate complex with a phenolic compound having enhanced acidity, and heating the obtained support in an inert diluent;

[0014] (2) The solid support prepared in step (1) is mixed with a titanium compound Ti(OR 1 ) n Cl 4-n , halogenated hydrocarbons and internal electron donors are contacted to react to obtain a main catalyst in the form of solid spherical particles;

[0015] (3) The main catalyst is brought into contact with an organoaluminum compound co-catalyst and an external electron donor as a selectivity control agent to obtain an olefin polymerization catalyst.

[0016] Furthermore, the amount ratio of the acid-enhanced phenolic compound to the magnesium carbonate ethanolate complex is: the molar ratio of the phenolic compound to the Mg element in the magnesium carbonate ethanolate complex is (0.01-10):1, and more preferably (0.1-8):1.

[0017] Furthermore, the magnesium carbonate ethanolate complex has the following structural formula:

[0018] Mg(OEt) 2 (CO 2 ) x , where x = 1 to 2;

[0019] The magnesium carbonate ethanolate complex is prepared by reacting ethoxy magnesium and carbon dioxide in excess ethanol;

[0020] The acid-enhanced phenolic compound is a phenolic compound having 1 to 2 aromatic rings and 1 to 2 electron-withdrawing substituents on the rings;

[0021] Further preferably, the acid-enhanced phenolic compound is a phenolic compound having an aromatic ring and an electron-withdrawing substituent, the electron-withdrawing substituent is a group without active hydrogen, and the substitution position is preferably located on a ring carbon atom at the ortho or para position relative to the phenolic hydroxyl group.

[0022] Furthermore, the inert diluent in step (1) includes linear alkyl alcohols, aromatic hydrocarbons, aromatic halogenated hydrocarbons or alkoxysilanes and mixtures thereof;

[0023] The temperature of the heat treatment is 80°C to 170°C. It needs to be heated to at least 80°C during the preparation. The upper limit of the heat treatment is the boiling point of the diluent used. The most commonly used diluents are chlorobenzene and tetraethoxysilane in the embodiment. When chlorobenzene is used, it boils at 130°C, and when tetraethoxysilane is used, it can be heated to 165°C. Therefore, the heat treatment temperature is generally 80 to 170°C, preferably 90 to 120°C. Heating is performed until the effervescence phenomenon formed by the escape of bubbles in the reaction system disappears. The purpose is to remove at least a portion of the carbon dioxide and / or ethanol present in the magnesium carbonate ethanolate / phenolic compound adduct by heating, so as to meet the needs of subsequent reactions to prepare the main catalyst.

[0024] Furthermore, the titanium compound Ti(OR 1 ) n Cl 4-n Medium R 1 It is an alkyl or aryl group containing 1 to 10 carbon atoms, and n is 1 to 4;

[0025] The halogenated hydrocarbons are halogenated hydrocarbons having up to 12 carbon atoms, which contain at least one halogen atom, preferably chlorine or bromine, and if they are aliphatic halogenated hydrocarbons, they contain at least 2 halogen atoms.

[0026] The internal electron donor is one or more of monobasic aliphatic carboxylic acid ester, polybasic aliphatic carboxylic acid ester, aromatic carboxylic acid ester compounds; or a 1,3-diether compound, whose molecular structure is R 2 O-CH 2 -CR 4 R 5 -CH 2 -OR 3 , where R 2 and R 3 are the same alkyl groups containing 1 to 10 carbon atoms, R 4 and R 5 is the same or different one of an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms, an arylalkyl group containing 7 to 40 carbon atoms, and an arylalkenyl group containing 8 to 40 carbon atoms;

[0027] The contact reaction in step (2) is carried out at room temperature to 150° C., the reaction time is 1 to 10 hours, the amount of the titanium compound used is such that the molar ratio of the Ti element in the titanium compound to the Mg element in the solid particle carrier is Ti:Mg=(1 to 40):1, and the amount of the internal electron donor used is such that the molar ratio of the electron donor to the Mg element in the solid particle carrier is (0.01 to 10):1.

[0028] After the slurry obtained by completing the above contact reaction once is filtered or decanted to remove the liquid, the solid particles can be repeatedly treated with the mixture of the titanium compound and the halogenated hydrocarbon under the same reaction conditions as above for at least one more time.

[0029] The mass percentage of Ti element in the main catalyst obtained in step (2) is 1-5%, the mass percentage of Mg element is 10-30%, the mass percentage of Cl element is 40-70%, and the mass percentage of internal electron donor is 1-30%.

[0030] Furthermore, the organoaluminum compound co-catalyst described in step (3) includes trialkylaluminum, alkoxyaluminum compound or alkylaluminum halide, wherein each alkyl group independently has 2 to 6 carbon atoms; the amount used is such that the molar ratio of Al element in the organoaluminum compound co-catalyst to Ti element in the main catalyst is (1 to 150):1.

[0031] Furthermore, the external electron donor as the selectivity control agent in step (3) is a 6 R 7 Si(OR 8 )(OR 9 ) of a hydrocarbyldihydrocarbyloxysilane, wherein R 6 , R 7 , R 8 , R 9 is a straight chain or branched chain alkyl or cycloalkyl group containing 1 to 20 carbon atoms, R 6 , R 7 Optional same or different, R 8 , R 9 Optionally the same or different; the dosage is the molar ratio of the external electron donor to the Al element in the organic aluminum compound co-catalyst is (0.1-500):1.

[0032] The present invention also provides an olefin polymerization catalyst prepared by the method.

[0033] The present invention also provides an application of the catalyst in polymerizing low-carbon alpha-olefins, especially propylene.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] In the olefin polymerization catalyst of the present invention, the main catalyst component is prepared by contacting and reacting a titanium compound, a halogenated hydrocarbon, an internal electron donor and a solid particle carrier, wherein the solid particle carrier is obtained by heating an adduct generated by the reaction of magnesium carbonate ethanolate and a phenolic compound with enhanced acidity. The carrier can be spherical, and thus can provide a polymerization product with good performance, including a relatively high bulk density and a relatively narrow particle size distribution.

[0036] The carbonation treatment of magnesium ethoxide actually increases the acidity of the final solid carrier. The present invention further investigates the effect of the change in acidity on the carrier performance and finds that the use of substituted phenols with pKa=7-9 has a positive effect on the particle performance of the final precipitated solid carrier, while when pKa≥10 (such as methyl, hydroxy substituted phenols), the weakened acidity makes it difficult for the carrier to precipitate. This is described in the following specific embodiments.

[0037] The process of forming a catalyst by reacting the obtained carrier with the titanium compound, halogenated hydrocarbon and internal electron donor is a reaction mechanism well known to those skilled in the art of magnesium-titanium catalysts for olefin polymerization.

[0038] The phenolic compounds added previously do not appear in the chromatographic analysis of the main catalyst formed. Therefore, it is believed that the phenolic compounds added during the carrier treatment do not participate in the chemical reaction, but only form a complex. As for the role of the complex in the preparation process of the main catalyst and how it is replaced, further experiments are still underway and no conclusion has been drawn.

[0039] In terms of effect, the activity of the main catalyst is improved, and the improvement effects of increasing the stacking density and the concentration of the particle size distribution are quite obvious. Compared with the existing technology, it can operate more stably and efficiently on large-scale olefin polymerization process equipment. DETAILED DESCRIPTION

[0040] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0041] Any features such as preparation methods, materials, structures or composition ratios that are not clearly described in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0042] The preparation method of the olefin polymerization catalyst of the present invention comprises the following steps:

[0043] (1) preparing a spherical particle solid support by reacting a magnesium carbonate ethanolate complex with a phenolic compound with enhanced acidity, and heating the obtained support in an inert diluent, and using the treated solid particle support for the preparation of an olefin polymerization main catalyst;

[0044] (2) The solid support prepared in (1) is mixed with a titanium compound Ti(OR) n Cl 4-n , halogenated hydrocarbons and internal electron donors are contacted to react to obtain a main catalyst in the form of solid spherical particles;

[0045] (3) The main catalyst is brought into contact with an organoaluminum compound co-catalyst and an external electron donor as a selectivity control agent to obtain the high-activity olefin polymerization catalyst of the present invention.

[0046] The catalyst can be used to polymerize low-carbon alpha-olefins to produce polymer products with relatively narrow particle size distribution and good properties.

[0047] Wherein said magnesium carbonate ethanolate complex is to react and prepare the solution in excessive ethanol by magnesium ethoxy and carbon dioxide.This preparation technology is known in the art, for example should be known in the disclosure of US 4522588, US4540679 and US 4728705 from United States Patent (USP).Usually, the method for preparing magnesium carbonate ethanolate complex solution comprises that carbon dioxide is added in the slurries that magnesium ethoxy and ethanol form, and the adding method comprises that gaseous carbon dioxide is adopted bubbling form to pass into slurries or directly adds solid dry ice in slurries.Through the interaction with carbon dioxide and ethanol, magnesium ethoxy is dissolved, and the magnesium carbonate ethanolate complex shown in the following formula is formed:

[0048] Mg(OEt) 2 (CO 2 ) x

[0049] Where x=1-2, the carbonate complex is dissolved in excess ethanol to form a solution. The process of interaction can be judged by observing the disappearance of insoluble ethoxy magnesium.

[0050] Then the magnesium carbonate ethanolate complex is reacted with an acidic phenolic compound, wherein the acidic phenolic compound is selected from phenol or substituted phenol, and the acidity of the phenolic compound is enhanced by the presence of an electron-withdrawing group as a substituent on the carbon atom of the phenolic ring. The types of electron-withdrawing substituents are well known in the art and generally include those groups that cause sufficient electron-withdrawing properties as aromatic ring substituents, such as groups that can reduce the pKa value of the substituted phenolic compound to less than about 9.9 in aqueous solution. Preferred electron-withdrawing groups do not contain active hydrogen. These electron-withdrawing substituents can be listed as: nitro (-NO 3), cyano (-CN), chlorine (-Cl), bromine (-Br), carboxyl (-COOH), alkoxy (-OR), aldehyde (-CHO) and the like, but excluding hydroxyl (-OH) or alkyl (-R). They are suitable ring substituents on the phenolic compounds for enhancing acidity of the present invention. At the same time, suitable phenolic compounds for enhancing acidity have 1 to 2 aromatic rings, and the rings have 1 to 2 electron-withdrawing substituents as described above, preferably located on the ring carbon atoms in the ortho or para position relative to the phenolic hydroxyl group. Therefore, suitable phenolic compounds for enhancing acidity can be listed as: o-nitrophenol, p-nitrophenol, p-chlorophenol, p-hydroxybenzaldehyde, 2-ethoxyphenol, p-cyanophenol, 4-ethoxyphenol, 4-acetoxyphenol, 2-methoxyphenol, 2,4-dinitrophenol, 2-nitro-1-hydroxynaphthalene and 4-cyano-1-hydroxynaphthalene, etc., one or a mixture, preferably a phenolic compound with one aromatic ring and one substituent.

[0051] The contact reaction of the magnesium carbonate ethanolate complex and the phenolic compound is carried out in an inert diluent, and the reaction is promoted by conventional methods such as shaking or stirring to promote mixing. The reaction temperature is 15 to 40° C., the molar ratio of the phenolic compound to the Mg element in the magnesium carbonate ethanolate complex is (0.01 to 10):1, preferably (0.1 to 8):1, and the reaction time is 1 to 10 hours.

[0052] Described inert diluent refers to the diluent that all can not react for magnesium carbonate ethanolate complex, phenolic compound and their reaction product, and must guarantee that magnesium carbonate ethanolate complex and phenolic compound are soluble therein.Therefore described diluent comprises straight chain alkyl alcohol, aromatic hydrocarbon, aromatic halogenated hydrocarbon or alkoxysilane and their mixture, can be enumerated as: ethanol, benzene, toluene, dimethylbenzene, chlorobenzene, dichlorobenzene, bromobenzene, tetramethoxysilane, tetraethoxysilane and trimethoxy propoxy silane etc.Preferred straight chain alkyl alcohol or the mixture based on branched alkyl alcohol are as diluent.Consider that magnesium carbonate ethanolate complex itself is the solution form in ethanol, particularly preferred ethanol or the mixture based on ethanol are as diluent.

[0053] As mentioned above, the whole system of magnesium carbonate ethanolate complex and phenolic compound is in solution state when diluent is just added. As the reaction proceeds, the reaction product is insoluble in the diluent, becomes solid particles and gradually precipitates. The solid particles are adducts of carbonated magnesium ethanolate and phenolic compound parts, which can be collected by conventional means such as filtration or decantation. The adduct can be represented by the following empirical formula:

[0054] Mg(CO 2 )(OEt)(A)·EtOH

[0055] A represents the phenol oxide anion, which is obtained by losing hydrogen from the phenol group in the phenolic compound that enhances the acidity.

[0056] The solid particles obtained by the above reaction are subjected to heat treatment in a high-boiling point inert diluent to obtain a spherical solid particle carrier for preparing the olefin polymerization main catalyst of the present invention. The high-boiling point diluent refers to a diluent with a normal pressure boiling point higher than 80°C, preferably a diluent higher than 100°C, preferably an aromatic halogenated hydrocarbon and a tetraalkoxysilane. With the heating treatment, the slurry will show effervescence due to the escape of bubbles. It is necessary to treat until the effervescence is reduced or completely stopped, and then recover the obtained solid particle carrier by filtering or decantation. The solid particle carrier is usually washed with a light alkane and dried before being used in the subsequent preparation of the main catalyst without further treatment. The light alkane includes C 5 ~C 10 Aliphatic hydrocarbons include one or a mixture of isopentane, n-hexane, n-heptane, n-octane, isooctane and n-decane, and preferably n-hexane, n-heptane or isooctane is used.

[0057] If the diluent used in the solid particle reaction precipitation production process has a low boiling point, it is necessary to first recover the solid particles from the slurry produced by the above reaction by filtration or decantation before heating treatment, and then mix it with a high boiling point diluent and heat it to an effervescent state for treatment.

[0058] Of course, in actual implementation, considering the simplicity of process operation, the diluent required for heat treatment and the diluent used in the aforementioned magnesium carbonate ethanolate complex / phenolic compound contact reaction can also be considered together, and the solid particles can be directly heat treated in the contact precipitated diluent. However, this method requires two points to be guaranteed: ① the diluent can meet the requirements of solid particles precipitating to achieve the desired spherical morphology; ② to ensure the required temperature for heat treatment.

[0059] Regardless of which of the above-mentioned heating treatment methods is adopted, the purpose is to remove at least a portion of the carbon dioxide and / or ethanol present in the magnesium carbonate ethanolate / phenolic compound adduct by heating to meet the requirements of the subsequent reaction to prepare the main catalyst.

[0060] The main catalyst for olefin polymerization of the present invention is a solid carrier and a titanium compound Ti(OR 1 ) n Cl 4-n , an optional halogenated hydrocarbon and an internal electron donor. The reaction is carried out by conventional means such as shaking or stirring to promote mixing.

[0061] The titanium compound Ti(OR 1 ) n Cl 4-n , R1 It is an alkyl or aryl group containing 1 to 10 carbon atoms, and n is 1 to 4. For example, diethoxytitanium dichloride, dihexyloxytitanium dichloride, isopropoxytitanium trichloride, phenoxytitanium trichloride, titanium tetrachloride, etc., or a mixture thereof. 1 An alkyl group having 1 to 4 carbon atoms is preferred, and titanium tetrachloride is particularly preferred.

[0062] The optional halogenated hydrocarbons described herein are halogenated hydrocarbons containing up to 12 carbon atoms, preferably containing up to 9 carbon atoms, which contain at least one halogen atom, preferably chlorine or bromine, and if aliphatic halogenated hydrocarbons, contain at least 2 halogen atoms. For example, suitable aliphatic halogenated hydrocarbons can be one or a mixture of methylene chloride, methylene bromide, chloroform, carbon tetrachloride, 1,2-dibromomethane, 1,1,3-trichloropropane, trichlorocyclohexane, dichlorofluoromethane and tetrachloroisooctane. Suitable aromatic halogenated hydrocarbons can be one or a mixture of chlorobenzene, bromobenzene, dichlorobenzene and chlorotoluene. Among aliphatic halogenated hydrocarbons, carbon tetrachloride and 1,1,2-trichloroethane are preferred, and chlorobenzene is preferred among aromatic halogenated hydrocarbons.

[0063] The internal electron donor is one or more of a monobasic aliphatic carboxylic acid ester, a polybasic aliphatic carboxylic acid ester, and an aromatic carboxylic acid ester compound. Examples thereof include benzoic acid esters, phthalic acid esters, malonic acid esters, succinic acid esters, glutaric acid esters, and the like, such as ethyl benzoate, diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, diethyl malonate, dibutyl malonate, diethyl 2,3-diisopropylsuccinate, diisobutyl 2,3-diisopropylsuccinate, di-n-butyl 2,3-diisopropylsuccinate, dimethyl 2,3-diisopropylsuccinate, diisobutyl 2,2-dimethylsuccinate. Esters, diisobutyl 2-ethyl-2-methylsuccinate, diethyl 2-ethyl-2-methylsuccinate, diethyl glutarate, diethyl adipate, dibutyl adipate, diethyl sebacate, dibutyl sebacate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimellitate, tributyl trimellitate, triethyl biphenyl trimellitate, tributyl biphenyl trimellitate, tetraethyl pyromellitate, tetrabutyl pyromellitate, etc., preferably aromatic carboxylic acid esters and succinic acid ester compounds, and ethyl benzoate and diisobutyl phthalate are particularly preferred among the aromatic carboxylic acid esters.

[0064] The internal electron donor may also be a 1,3-diether compound, whose molecular structure is R 2 O-CH 2 -CR 4 R 5 -CH 2 -OR 3 , where R 2 and R 3are the same alkyl groups containing 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, R 4 and R 5 It is one of the same or different alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, arylalkyl groups having 7 to 40 carbon atoms, and arylalkenyl groups having 8 to 40 carbon atoms. Examples thereof include 2-isopentyl-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 1,2-bis(methoxymethyl)cyclohexane, 9,9-bis(methoxymethyl)fluorene, 9,9-bis(methoxymethyl)-2,3,6,7-tetramethylfluorene, 9,9-bis(methoxymethyl)-2,7-dimethylfluorene, 9, 9-bis(methoxymethyl)-2,7-diisopropylfluorene, 9,9-bis(methoxymethyl)-2,7-di-tert-butylfluorene, 9,9-bis(methoxymethyl)-2,8-dimethylfluorene, 9,9-bis(methoxymethyl)-3,6-dimethylfluorene, 9,9-bis(methoxymethyl)-3,6-di-tert-butylfluorene, 9,9-bis(methoxymethyl)-3,6-diisopropylfluorene, 9,9-bis(methoxymethyl)-4,5-dimethylfluorene, 9,9-bis(methoxymethyl)-2-methylfluorene, 9,9-bis(methoxymethyl)-4-methylfluorene. Diether compounds containing an aryl group are preferred.

[0065] The internal electron donor can be a single compound added to the reaction system, or a mixture of two or more compounds added to the reaction system.

[0066] The order of the solid particle carrier, titanium compound, halogenated hydrocarbon and internal electron donor in the contact reaction can be optional. For example, the solid particle carrier can be first mixed with the titanium compound and halogenated hydrocarbon, and then the internal electron donor can be added to the resulting mixture for reaction; or the internal electron donor can be first contacted with the solid carrier particles for reaction, and then added to the mixture of the titanium compound and the halogenated hydrocarbon for further reaction.

[0067] The contact reaction of the solid particle carrier, the titanium compound, the halogenated hydrocarbon and the internal electron donor can be carried out at room temperature to 150°C. To ensure better interaction between the raw materials in the system, the temperature of the contact reaction is preferably 80 to 130°C. The contact reaction time can be 1 to 10 hours. The titanium compound is added once, and the molar ratio of the Ti element in the titanium compound and the Mg element in the solid particle carrier is Ti:Mg=(1 to 40):1, preferably Ti:Mg=(2 to 30):1.

[0068] During the preparation of the main catalyst, it is necessary to ensure that a sufficient amount of titanium compound is used to convert at least most of the anions in the solid particle carrier into halides. This conversion is generally referred to as halogenation in the art, and if necessary, the operation must be repeated multiple times. Therefore, after the slurry obtained by the above contact reaction is filtered or decanted to remove the liquid, the solid particles can be treated with a mixture of titanium compound and halogenated hydrocarbon under the same reaction conditions as above for at least one more time, preferably 2 to 5 times. In addition, in order to ensure the halogenation effect, another halogenating agent, such as an acyl halide, can be added at the same time to further promote halogenation.

[0069] During the preparation of the main catalyst, it is also necessary to ensure that a sufficient amount of internal electron donor is provided. The amount of the internal electron donor is such that the molar ratio of the electron donor to the Mg element in the solid particle carrier is 0.01:1 to 10:1, preferably 0.06:1 to 0.4:1. The internal electron donor can be added once during the initial contact reaction between the solid particle carrier and the titanium compound and the halogenated hydrocarbon, or it can be added separately during multiple halogenation processes, but the total amount is controlled within the above-mentioned amount range.

[0070] The spherical particles obtained after the main catalyst preparation process are usually washed with light alkanes, which include C 5 ~C 10 Aliphatic hydrocarbons can be listed as one of isopentane, n-hexane, n-heptane, n-octane, isooctane, and n-decane, or a mixture of multiple thereof, preferably n-hexane, n-heptane, or isooctane. Washing usually requires multiple times, and the criterion for completion is that the resulting clear liquid portion no longer contains residual titanium. Then, heating and drying under nitrogen is performed to obtain a main catalyst product that can be used for polymerization. The main catalyst thus obtained does not contain oxygen and active hydrogen compounds and can be stably stored. The mass percentage of the Ti element in the main catalyst is 1 to 5%, the mass percentage of the Mg element is 10 to 30%, the mass percentage of the Cl element is 40 to 70%, and the mass percentage of the internal electron donor is 1 to 30%.

[0071] The main catalyst is contacted with an organic aluminum co-catalyst and an external electron donor as a selectivity control agent to produce a high-activity olefin polymerization catalyst.

[0072] The cocatalyst is an organoaluminum compound selected from aluminum-based cocatalysts commonly used with titanium-based main catalysts in the art. It can be trialkylaluminum, alkoxyaluminum compounds or alkylaluminum halides, wherein each alkyl group independently has 2 to 6 carbon atoms. Preferred halogen-free organoaluminum compounds, particularly preferred are trialkylaluminum, such as triethylaluminum, triisobutylaluminum, triisopropylaluminum and diethylhexylaluminum. Triethylaluminum is most preferred. The amount of the cocatalyst is such that the molar ratio of the Al element in the trialkylaluminum to the Ti element in the main catalyst is (1 to 150):1, preferably about (10 to 100):1.

[0073] When the main catalyst of the present invention is used for olefin polymerization, an external electron donor as a selectivity control agent is added during the polymerization process according to the type of internal electron donor compound, the process and the needs of the resin product. For example, as is well known in the art, the high stereoselectivity of the catalyst containing phthalate can only be obtained in the presence of an external electron donor. When 1,3-diether compounds are used, no external electron donor may be added.

[0074] The external electron donor that can be used in the present invention is a structural formula R 6 R 7 Si(OR 8 )(OR 9 ) of a hydrocarbyldihydrocarbyloxysilane, wherein R 6 , R 7 , R 8 , R 9 is a straight chain or branched chain alkyl or cycloalkyl group containing 1 to 20 carbon atoms, R 6 , R 7 Optional same or different, R 8 , R 9 Optional identical or different. For example, methylcyclohexyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, dicyclohexyl dimethoxysilane, dicyclopentyl dimethoxysilane, methylcyclohexyl diethoxysilane, diisopropyl diethoxysilane, diisobutyl diethoxysilane, dicyclohexyl diethoxysilane, dicyclopentyl diethoxysilane, methylcyclohexyl dipropoxysilane, diisopropyl dipropoxysilane, diisobutyl dipropoxysilane, dicyclohexyl dipropoxysilane, dicyclopentyl dipropoxysilane, methylcyclohexyl dibutoxysilane, diisopropyl dibutoxysilane, diisobutyl dibutoxysilane, dicyclohexyl dibutoxysilane, dicyclopentyl dibutoxysilane, etc. Preferably, one of methylcyclohexyldimethoxysilane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane and diisobutyldimethoxysilane is used. There is no particular order for adding the external electron donor to the polymerization system, and the molar ratio of the external electron donor to the Al element in the co-catalyst trialkylaluminum is (0.1-500):1, preferably (5-300):1.

[0075] The contact of the components of the high-activity olefin polymerization catalyst of the present invention is usually completed directly in situ in the polymerization system during olefin polymerization. Of course, according to process requirements, the components can also be pre-mixed and contacted in a suitable reactor outside the polymerization system, and lower α-olefins can be selectively added during the contact process, and the catalyst produced therefrom is then introduced into the polymerization reactor.

[0076] The high-activity olefin polymerization catalyst formed by the main catalyst component prepared from the solid particle carrier obtained by heat treatment of magnesium carbonate ethanolate / phenolic compound adduct provided by the present invention can be used for the polymerization of low-order alpha-olefins, especially the polymerization reaction of straight-chain alpha-olefins, wherein the alpha-olefin contains 2 to 4 carbon atoms, i.e. ethylene, propylene or 1-butene. The precise polymerization method is usually conventional, but the olefin polymerization of the present invention, because the solid particle carrier obtained by heat treatment of magnesium carbonate ethanolate / phenolic compound adduct is used, the carrier can be spherical, so it can provide a polymer product with good properties, including a relatively high bulk density and a relatively narrow particle size distribution. The high activity and stereoregularity of the catalyst make it possible to obtain a polymer product with desired properties without the need for deashing or extraction steps.

[0077] As is well known in the art, when a single type of α-olefin monomer is provided in the polymerization process using the catalyst of the present invention, a highly isotactic homopolymer is obtained. Similarly, when two or more α-olefins are provided in the polymerization system using the catalyst of the present invention, binary or ternary copolymers can be prepared, such as the production of random copolymers of polypropylene or impact block copolymers EPR, which are well known in the art.

[0078] The polymerization is carried out according to known methods and can be carried out in bulk in liquid monomers, or in slurry polymerization in an inert solvent such as propane, or in the gas phase, or by a combined polymerization process in the gas and liquid phases. The operation can be carried out in a batch mode or in a semi-continuous or continuous process. The polymerization temperature is generally 50-100°C, the polymerization pressure is 0.1-5.0 MPa, and the reaction time is 0.2-10 hours. During the polymerization, the molecular weight and to some extent the properties of the polymer product will be affected by the supply of hydrogen as is well known in the art.

[0079] When the catalyst of the present invention is used for the production of propylene homopolymer and copolymer of propylene and ethylene, the weight average molecular weight of the propylene polymer is usually (1 to 200)×10 4 g / mol, and the melt index (at 230°C and under 2.16 kg load) is 0.01-2000 g / 10 min, preferably 0.1-100 g / 10 min, and the content of the rubber phase in the propylene-ethylene copolymer is between 10 and 40 wt%.

[0080] The following is a specific preparation implementation of the main catalyst component used in the high-activity olefin polymerization catalyst of the present invention:

[0081] The specific composition determination method of each component content in the main catalyst body obtained in the embodiment is:

[0082] (1) A certain amount of catalyst sample was extracted with heptane and sulfuric acid solution. The obtained extract was filtered and the aqueous layer was used for the determination of Mg, Ti and Cl.

[0083] Among them: Mg 2+ The ion content was determined by EDTA (disodium ethylenediaminetetraacetate) titration method; the Cl- ion content was determined by potentiometric titration method; and the Ti content was analyzed by absorbance method.

[0084] (2) A certain amount of catalyst sample is extracted with heptane and sulfuric acid solution, the obtained extract is filtered, the obtained solvent layer is quantitatively prepared with a volumetric flask, and the content of the electron donor compound aromatic carboxylic acid ester is determined by gas chromatography using an internal standard method.

[0085] The specific composition determination method of the performance indexes of each polymer obtained in the embodiment is:

[0086] (1) Determination of polymer melt index MI: Determined in accordance with GB3682-2000;

[0087] (2) Determination of polymer bulk density BD: Determined according to ASTM-D1895;

[0088] (3) Determination of xylene soluble content (XS%): Mainly used to show the stereoregular selectivity of olefin polymerization catalysts. In this test, a certain amount of polymer sample is first heated and refluxed in xylene. The amorphous (atactic) part and a small amount of low molecular weight crystalline part in the sample will dissolve in xylene. After the reflux is completed, the flask of xylene solution is immersed in a 25°C water bath for 1 hour (without stirring). After the insoluble part precipitates, it is filtered and removed. The remaining solution is divided into 3 equal parts, evaporated separately, and the solid obtained is dried and weighed, which is the weight of xylene solubles. XS% = (xylene soluble weight + polymer sample weight) × 100%. The average value of the 3 measurements is taken as the final measurement result.

[0089] (4) Determination of polymer particle size: The particle size of the polymer powder was measured using a laser particle size analyzer. The particle size distribution curve was tested using a dry method to obtain the D(10), D(50) and D(90) particle size data, as well as the volume average particle size and span SPAN = (D90-D10) / D50, which characterize the concentration of the particle distribution.

[0090] Example 1

[0091] 17.5 g of ethoxymagnesium and 52.0 g of ethanol were added to a 250 ml reaction bottle with magnetic stirring, and the mixture was stirred and mixed. Then, dry ice was added gradually under stirring until a clear magnesium carbonate ethanolate solution was obtained.

[0092] 3.65 g of tetraethoxysilane was added to the above 87.25 g of ethanol solution of magnesium carbonate ethanolate (wherein the Mg content was 125 mmol), and the reaction was continued with stirring for 1 hour. 17.38 g of p-nitrophenol dissolved in 17.4 g of ethanol was added to the above stirred solution. After stirring overnight at room temperature, the resulting slurry was filtered, the solid was washed with isooctane and dried under flowing nitrogen. 33.6 g of yellow particles were obtained. The particle size of the particles was in the range of 2 to 14 μm. 20 g of the above solid was added to 150 g of chlorobenzene, and the mixed slurry was placed in a 164°C oil bath and heated and boiled for 1 hour. Cool to room temperature, filter and recover to obtain 15.8 g of solid particle carrier. At this time, the carrier is yellow-orange. Wash the solid with isooctane and dry under nitrogen.

[0093] Example 2

[0094] 17.5 g of magnesium ethoxide was mixed with 55.65 g of ethanol containing 3.65 g of tetraethoxysilane in a 250 ml reaction bottle with magnetic stirring, and then dry ice was added in portions under stirring until a clear magnesium carbonate ethoxide solution was obtained.

[0095] 16.2g of p-chlorophenol was added to the ethanol solution of 90.8g of magnesium carbonate ethanolate (wherein the Mg content was 125mmol). The mixture was stirred at 60°C for 2 hours and then cooled to room temperature. The solid was filtered and recovered, washed with isooctane and dried under nitrogen. The yield was 28.7g of solid particles with a particle size in the range of 15-20μm. After stirring overnight at room temperature, the resulting slurry was filtered, the solid was washed with isooctane and dried under flowing nitrogen. 18.4g of the above solid particles were added to 225g of tetraethoxysilane, and the mixture was stirred at 80°C for about 1 hour. Then heated to near boiling and stirred for another 7 hours. After the reaction was completed, it was cooled to room temperature, the solid was filtered and recovered, washed with isooctane and dried under flowing nitrogen. 14g of solid particle carrier was obtained.

[0096] Example 3

[0097] 350 g of ethoxymagnesium (containing 3.06 mol Mg) was mixed with 1113 g of ethanol containing 84.6 g of tetraethoxysilane in a 5 L magnetic stirring reactor, and then dry ice was added gradually under stirring until a clear magnesium carbonate ethanolate solution was obtained.

[0098] 353.5 g of p-nitrophenol dissolved in 320 g of ethanol was added to the above solution. The mixture was stirred at 400-500 rpm overnight at room temperature. The obtained slurry was collected by filtration and washed once with ethanol and then with isooctane and dried under flowing nitrogen. 728.2 g of spherical solid particles were obtained, and the particle size of the particles was in the range of 3 to 8 μm. The obtained solid particles were subjected to the following treatments in batches:

[0099] A. Heat 20 g of the above solid particles in 150 g of chlorobenzene until boiling for 1 hour to obtain 15.9 g of solid particle carrier for the preparation of the main catalyst.

[0100] B. Boil 20.67 g of the above solid particles in 200 g of tetraethoxysilane for 1 hour to obtain 15.6 g of solid particle carrier for main catalyst preparation.

[0101] Comparative Example

[0102] 17.5 g of magnesium ethoxide was mixed with 55.65 g of ethanol containing 3.65 g of tetraethoxysilane in a 250 ml reaction bottle with magnetic stirring, and then dry ice was added in portions under stirring until a clear magnesium carbonate ethoxide solution was obtained.

[0103] 16.2 g of p-chlorophenol was added to the ethanol solution of 90.8 g of magnesium carbonate ethanolate (wherein the Mg content was 125 mmol). The mixture was stirred at 60 ° C for 2 hours and then cooled to room temperature. The obtained solid was filtered and recovered, washed with isooctane and dried under nitrogen. The yield was 28.7 g of solid particles with a particle size in the range of 15-20 μm. After stirring overnight at room temperature, the obtained slurry was filtered, the solid was washed with isooctane and dried under flowing nitrogen. 15.2 g of the carrier was taken out and no further treatment was performed, and it was directly used for the preparation of the main catalyst.

[0104] Example 4

[0105] The main catalyst preparation test was carried out on 1, 2, 3A and 3B prepared in Examples 1 to 3 and Comparative Examples as well as the five solid particle carriers of the Comparative Examples.

[0106] The solid particle carrier prepared by each embodiment and comparative example was added to 75ml chlorobenzene at room temperature, and 75ml titanium tetrachloride was added while stirring. After the addition, the temperature was raised to 75°C, 4ml diisobutyl phthalate (DIBP) was added and the reaction was kept at this temperature for 1 hour, and then the temperature was continued to be raised to 115°C and stirred for 3 hours. The resulting mixture was filtered while hot, and the solid thus recovered was continued to be stirred for 2 hours at 110°C with 75ml titanium tetrachloride and 75ml chlorobenzene and filtered while hot. Then continue to repeat 2 times to complete the preparation of the main catalyst. Then wash the filtered solid 2 times with 125ml isooctane at 90°C, and finally wash it 3 times with isooctane at room temperature. The main catalyst solid obtained was dried overnight under flowing nitrogen. The catalyst component content obtained is shown in Table 1.

[0107] Table 1 Example 4 obtained the main catalyst component content

[0108]

[0109]

[0110] Example 5

[0111] The main catalysts prepared in Example 4 were used as co-catalysts, triethylaluminum, and diisobutyldimethoxysilane as external electron donors to form olefin polymerization catalysts for propylene polymerization tests. The polymerization method is as follows:

[0112] In a 2-liter autoclave, nitrogen gas was used to purge at 70°C for 1 hour, and then the polymerization autoclave was replaced with gaseous propylene for 3 times. Under nitrogen protection, a certain amount of triethylaluminum (Al / Ti=150), diisobutyldimethoxysilane (Si / Ti=20), 10 ml of anhydrous hexane and 10-15 mg of solid catalyst main component were added successively. The autoclave was closed, 600 g of liquid propylene was added, and 0.04 g of hydrogen was added; the temperature in the autoclave was quickly raised to 70°C under stirring. After the polymerization reaction at 70°C for 1.0 hour, stirring was stopped, the unpolymerized propylene monomer was removed, and the polypropylene was collected and dried and weighed.

[0113] The aggregation results are shown in Table 2.

[0114] Table 2 Example 5 polymerization test results

[0115]

[0116] As can be seen from the above table, compared with the comparative example without any further treatment, the main catalyst prepared by the carrier obtained by heat treatment of the strong acidity phenolic compound proposed by the present invention shows significantly improved polymerization activity in the propylene polymerization process, and the obtained polymer product has a higher bulk density and a more concentrated particle size distribution. Compared with the prior art, it can operate more stably and efficiently on a large olefin polymerization process device.

Claims

1. A method for preparing an olefin polymerization catalyst, It is characterized in that The following steps are involved: (1) preparing a solid support of spherical particles by reacting a magnesium carbonate ethanolate complex with a phenolic compound having enhanced acidity, and heating the obtained support in an inert diluent; (2) The solid support prepared in step (1) is mixed with a titanium compound Ti(OR 1 ) n Cl 4-n , halogenated hydrocarbons and internal electron donors are contacted to react to obtain a main catalyst in the form of solid spherical particles; (3) The main catalyst is brought into contact with an organoaluminum compound co-catalyst and an external electron donor as a selectivity control agent to obtain an olefin polymerization catalyst.

2. The method for preparing an olefin polymerization catalyst according to claim 1, It is characterized in that The dosage ratio of the acid-enhanced phenolic compound to the magnesium carbonate ethanolate complex is: the molar ratio of the phenolic compound to the Mg element in the magnesium carbonate ethanolate complex is (0.01-10):

1.

3. The method for preparing an olefin polymerization catalyst according to claim 1 or 2, It is characterized in that The magnesium carbonate ethanolate complex has the following structural formula: Mg(OEt) 2 (CO 2 ) x , where x = 1 to 2; The magnesium carbonate ethanolate complex is prepared by reacting ethoxy magnesium and carbon dioxide in excess ethanol; The acid-enhanced phenolic compound is a phenolic compound having 1 to 2 aromatic rings and 1 to 2 electron-withdrawing substituents on the rings; The molar ratio of the Mg element in the phenolic compound and the magnesium carbonate ethanolate complex is (0.1-8):

1.

4. The method for preparing an olefin polymerization catalyst according to claim 3, It is characterized in that The acid-enhanced phenolic compound is a phenolic compound having an aromatic ring and an electron-withdrawing substituent. The electron-withdrawing substituent is a group that does not contain active hydrogen, and the substitution position is located on a ring carbon atom at an ortho or para position relative to the phenolic hydroxyl group.

5. The method for preparing an olefin polymerization catalyst according to claim 1, It is characterized in that The inert diluent in step (1) includes linear alkyl alcohols, aromatic hydrocarbons, aromatic halogenated hydrocarbons or alkoxysilanes and mixtures thereof; The temperature of the heating treatment is 80° C. to 170° C., and the heating is performed until the effervescence phenomenon formed by the escape of bubbles in the reaction system disappears.

6. The method for preparing an olefin polymerization catalyst according to claim 1, It is characterized in that The titanium compound Ti(OR 1 ) n Cl 4-n Medium R 1 It is an alkyl or aryl group containing 1 to 10 carbon atoms, and n is 1 to 4; The halogenated hydrocarbon is a halogenated hydrocarbon containing up to 12 carbon atoms, which contains at least one halogen atom. The internal electron donor is one or more of monobasic aliphatic carboxylic acid ester, polybasic aliphatic carboxylic acid ester, aromatic carboxylic acid ester compounds; or a 1,3-diether compound, whose molecular structure is R 2 O-CH 2 -CR 4 R 5 -CH 2 -OR 3 , where R 2 and R 3 are the same alkyl groups containing 1 to 10 carbon atoms, R 4 and R 5 is the same or different one of an alkyl group containing 1 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms, an arylalkyl group containing 7 to 40 carbon atoms, and an arylalkenyl group containing 8 to 40 carbon atoms; The mass percentage of Ti element in the main catalyst obtained in step (2) is 1-5%, the mass percentage of Mg element is 10-30%, the mass percentage of Cl element is 40-70%, and the mass percentage of internal electron donor is 1-30%. The contact reaction in step (2) is carried out at room temperature to 150° C., and the reaction time is 1 to 10 hours.

7. The method for preparing an olefin polymerization catalyst according to claim 1, It is characterized in that The organoaluminum compound co-catalyst described in step (3) includes trialkylaluminum, alkoxyaluminum compound or alkylaluminum halide, wherein each alkyl group independently has 2 to 6 carbon atoms; the amount used is such that the molar ratio of Al element in the organoaluminum compound co-catalyst to Ti element in the main catalyst is (1 to 150):

1.

8. The method for preparing an olefin polymerization catalyst according to claim 1, It is characterized in that The external electron donor used as the selectivity control agent in step (3) is a 6 R 7 Si(OR 8 )(OR 9 ) of a hydrocarbyldihydrocarbyloxysilane, wherein R 6 , R 7 , R 8 , R 9 is a straight chain or branched chain alkyl or cycloalkyl group containing 1 to 20 carbon atoms, R 6 , R 7 Optional same or different, R 8 , R 9 Optionally the same or different; the dosage is the molar ratio of the external electron donor to the Al element in the organic aluminum compound co-catalyst is (0.1-500):

1.

9. An olefin polymerization catalyst prepared by the method of claim 1.

10. Use of the catalyst according to claim 9 in polymerizing low-carbon α-olefins.

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