A spherical catalyst for olefin polymerization

Abstract

The present invention provides a spherical catalyst for olefin polymerization. The present invention first reacts a magnesium compound with an alcohol mixture in the presence of polyvinyl pyrrolidone and a multipolar functional group compound to form a complex solution, the complex solution reacts with an alkylene oxide compound to produce a solid adduct, the solid adduct is washed to obtain a spherical carrier, the spherical carrier reacts with a titanium compound to obtain an intermediate product, and the intermediate product reacts with titanium tetrachloride to obtain a spherical catalyst. The catalyst provided by the present invention has a simple and feasible preparation process, and the obtained spherical catalyst has a good morphology and a controlled size. The catalyst is highly active when used for olefin polymerization, especially ethylene polymerization, and shows good hydrogen adjustment sensitivity and a high 1-hexene insertion rate. In addition, the fine powder content in the polymer particles obtained by the catalyst is low.

Description

Technical Field

[0001] The invention belongs to the field of olefin polymerization catalysts, and in particular relates to a spherical catalyst used for olefin polymerization reaction. Background Art

[0002] In order to prepare spherical polyethylene with regular morphology, high bulk density and low fine powder content, a spherical carrier is often prepared based on the "complex effect", and then titanium tetrachloride is loaded on the carrier to obtain a spherical catalyst. At present, the mainstream spherical catalysts are mostly based on magnesium chloride alcoholate or ethoxymagnesium.

[0003] CN101544710 discloses a method for preparing an alcoholate of a ternary component of magnesium halide, alcohol and polyether. After the ternary components are reacted at high temperature to form a molten mixture, the mixture is rapidly cooled and formed by a low-temperature inert medium. The obtained carrier has good dispersibility, good particle morphology, and small particle size. The supported catalyst has high activity when used for olefin polymerization, especially propylene polymerization. The obtained polymer has good morphology and less fine powder. However, the above-mentioned preparation process is relatively complicated and consumes a lot of energy. In addition, in order to avoid the catalyst prepared from the alcoholate from breaking during the polymerization process, a dealcoholization step needs to be introduced, which further increases the energy consumption.

[0004] CN200910235562 discloses a novel alkoxy magnesium spherical carrier and its preparation method, and the catalyst is obtained by reacting with titanium tetrachloride in the presence of an internal electron donor. The preparation method does not require rapid cooling to precipitate the carrier, and the operation is relatively simple. It has high activity when used for propylene polymerization, and while maintaining high polymerization activity and directional ability, it shows good hydrogen adjustment sensitivity, and the polymer has high stereoregularity at a high melt index. However, the carrier has poor mechanical strength and is easily broken in the violent heat release titanium loading process, and the bulk density of the polypropylene finally obtained after propylene polymerization is low.

[0005] CN1563112 discloses spherical MgCl 2 - Preparation method of polyolefin catalyst supported by alcohol-organic complexing agent carrier. The internal electron donor diisobutyl phthalate (DIBP) is introduced in situ into the carrier synthesis, so that the obtained carrier has high mechanical strength, and titanium tetrachloride is added on this basis to obtain a spherical catalyst. However, the obtained catalyst particle size is large and the distribution is wide (D 50 : 70-200 μm), and the propylene polymerization activity is low.

[0006] In summary, the existing olefin polymerization catalyst carriers and preparation methods thereof have problems such as the carriers being easily broken during the titanium loading process, the process being complicated and the polymerization performance being poor. Summary of the invention

[0007] In order to improve the mechanical strength of the carrier, simplify the carrier preparation process, save energy, and achieve the purpose of improving the commercial value of the olefin polymerization catalyst, the present invention provides a spherical catalyst for olefin polymerization reaction, which is prepared by the following steps:

[0008] (1) reacting a magnesium compound with an organic compound containing active hydrogen at 30-160° C. in the presence of polyvinyl pyrrolidone and a multipolar functional group compound to form a complex solution;

[0009] (2) reacting the complex solution with an epoxy compound to precipitate a solid compound;

[0010] The epoxy compound is shown in the general formula (I):

[0011]

[0012] In the general formula (I), R 2 and R 3 are each independently selected from hydrogen, C 1 -C 5 A straight-chain or branched alkyl group, wherein the hydrogen atoms on the alkyl group may not be substituted, or may be substituted by a halogen atom X in an optional number;

[0013] (3) washing the solid compound obtained in step (2) with an inert alkane solvent to obtain a spherical carrier of magnesium compound;

[0014] (4) dispersing the magnesium compound spherical carrier obtained in step (3) in a high-viscosity inert hydrocarbon solvent, and adding a titanium compound at low temperature to react to obtain an intermediate product;

[0015] The titanium compound is shown in the general formula (II):

[0016]

[0017] R in the general formula (II) 1 '、R 2 '、R 3 '、R 4 'Each independently selected from C 1 –C 10 Alkyl

[0018] (5) dispersing the intermediate product in a high-viscosity inert hydrocarbon solvent, adding titanium tetrachloride to react with the intermediate product at low temperature, and washing the solid product with an inert alkane solvent to obtain a spherical catalyst;

[0019] Wherein, the multipolar functional group compound described in step (1) is a compound having a general formula of C n H 2n O nCompounds with multipolar functional groups, wherein n is 4-8;

[0020] The organic compound containing active hydrogen in step (1) is a compound of the general formula R(OH): m A compound or a mixture of compounds as shown, wherein R is C 1 -C 20 Hydrocarbyl, m≥1;

[0021] The inert alkane solvent described in step (3) is a solvent of the general formula C n H 2n+2 A mixture of one or more compounds as shown, wherein n≥5; the high viscosity inert hydrocarbon solvents described in step (4) and step (5) refer to straight chain, branched chain alkanes, alkyl-substituted cycloalkanes and alkyl-substituted aromatic hydrocarbons.

[0022] As a preferred embodiment of the present invention, per mole of magnesium, the amount of polyvinyl pyrrolidone used is 0.001 to 0.1 mole, the amount of the multipolar functional group compound used is 0.002 to 0.2 mole, the amount of the organic compound containing active hydrogen is 2 to 20 moles, the amount of the epoxy compound is 1 to 30 moles, the amount of the titanium compound is 0.05 to 1.5 moles, and the amount of titanium tetrachloride is 0.5 to 15 moles.

[0023] As a preferred embodiment of the present invention, the multipolar functional group compound in step (1) is one of glucose, fructose, sorbitol, galactose, cyclohexanehexol or a mixture of multiple thereof.

[0024] As a preferred embodiment of the present invention, the magnesium compound in step (1) is a mixture of one or more of magnesium halide, phenoxymagnesium chloride, isopropoxymagnesium chloride and butoxymagnesium chloride. The magnesium halide may be magnesium dichloride, magnesium dibromide or the like.

[0025] As a preferred embodiment of the present invention, R(OH) in step (1) m A mixture of two or three selected from methanol, ethanol, propanol, n-butanol, isobutanol, amyl alcohol, isopentanol, n-hexanol, 2-ethylhexanol, ethylene glycol, propylene glycol and glycerol.

[0026] As a preferred embodiment of the present invention, the epoxy compound described in step (2) is ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epichlorohydrin, epibromohydrin or epibromobutylene.

[0027] As a preferred embodiment of the present invention, the inert alkane solvent in step (3) is selected from a mixture of one or more of n-hexane, cyclohexane, n-heptane, n-octane and n-nonane.

[0028] As a preferred embodiment of the present invention, the high-viscosity inert hydrocarbon solvent described in step (4) and step (5) is a mixture of one or more of decane, paraffin oil, white oil, methyl silicone oil, and vaseline oil.

[0029] As a preferred embodiment of the present invention, the low temperature in step (4) and step (5) refers to -40 to 0°C, preferably -20 to -10°C.

[0030] The present invention also provides an application of a polymerization catalyst system comprising the aforementioned spherical catalyst component in the polymerization reaction of α-olefins. The general formula of α-olefins is CH 2 =CHR, preferably, R is hydrogen or an alkyl group with 1-12 carbon atoms. The α-olefin polymerization reaction may be an oligomerization reaction of α-olefins, or a copolymerization reaction using α-olefins as one of the polymerization monomers.

[0031] The catalyst provided by the present invention has a simple and feasible preparation process, and the obtained spherical catalyst has good morphology and controlled size. When used for olefin polymerization, especially ethylene polymerization, the catalyst has high activity, shows good hydrogen adjustment sensitivity and high 1-hexene insertion rate. In addition, the fine powder content in the polymer particles obtained by the catalyst is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The catalyst of Example 1 is spherical in shape;

[0033] Figure 2 is a distribution diagram of catalyst particle size of Example 1;

[0034] Figure 3 is a spherical morphology image of the polymer particles of Example 1;

[0035] Figure 4 is a particle size distribution diagram of the polymer particles of Example 1;

[0036] Figure 5 is the sphericity distribution diagram of the polymer particles of Example 1;

[0037] Figure 6 This is the catalyst particle size distribution diagram of Example 4. DETAILED DESCRIPTION

[0038] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0039] Test method:

[0040] 1. The Ti content of the catalyst was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0041] 2. The catalyst morphology was observed by scanning electron microscopy (SU8010, USA) and the particle size and particle size distribution of the catalyst were measured with the assistance of Image J software.

[0042] 3. The weight average molecular weight (M) of the polymer was determined by high temperature gel permeation chromatography (HT-GPC, PL-GPC-220, UK). w ) and molecular weight distribution (MWD).

[0043] 4. The branching degree of the polymer was determined using a nuclear magnetic resonance spectrometer (Bruker AC-80, 400 MHz).

[0044] 5. The particle size distribution of the polymer was tested and analyzed using a laser particle size analyzer (Mastersizer 2000, USA).

[0045] 6. The microstructure of the polymer particles was observed using a scanning electron microscope (SU3500 / SU8010, USA).

[0046] 7. The bulk density of the polymer particles is measured according to the American standard ASTM-D1895.

[0047] 8. The sphericity of the polymer was determined using the BT-2900LD dynamic image particle size and shape analysis system (dry method).

[0048] Select magnesium halide MgX from magnesium compounds 2 For example, the preparation route of the spherical catalyst of the present invention is as follows:

[0049] 1. Preparation of Spherical Carriers

[0050] (a) Under nitrogen protection, polyvinyl pyrrolidone and multipolar functional group compound C n H 2n O n In the presence of 2 reacting with an alcohol mixture at 30-160°C to form a complex solution;

[0051] (b) reacting the above complex solution with the alkylene oxide compound represented by formula (I) at 30-160°C to produce a solid adduct, and washing the solid adduct obtained in (2) with an inert alkane solvent to obtain a magnesium halide spherical carrier.

[0052]

[0053] In the general formula (I), R 2 and R3 are the same or different and are hydrogen or a C1-C5 linear or branched alkyl group, wherein the hydrogen on the alkyl group is optionally substituted by a halogen atom X;

[0054] The general formula is C n H 2n O n The multipolar functional group compound is one of glucose, fructose, sorbitol, galactose, cyclohexanehexol or a mixture of multiple thereof.

[0055] The epoxy compound described in the general formula (I) is a mixture of one or more of ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epichlorohydrin, epibromohydrin or epibromobutylene oxide.

[0056] 2. Preparation of spherical catalyst

[0057] The spherical carrier is dispersed in a high-viscosity inert hydrocarbon solvent, and a titanium compound is added at low temperature to react to obtain an intermediate product; the intermediate product is dispersed in a high-viscosity inert hydrocarbon solvent, and titanium tetrachloride is added at low temperature to react with it, and the solid product is washed with an inert alkane solvent to obtain a spherical catalyst.

[0058] The titanium compound is shown in the general formula (II):

[0059]

[0060] R in the general formula (II) 1 '、R 2 '、R 3 '、R 4 'Same or different, C 1 –C 10 of alkyl.

[0061] The high viscosity inert hydrocarbon solvent is a mixture of one or more of decane, paraffin oil, white oil, methyl silicone oil, and vaseline oil.

[0062] Calculated per mole of magnesium, the amount of polyvinyl pyrrolidone used is 0.001 to 0.1 mole, the amount of the multipolar functional group compound used is 0.002 to 0.2 mole, the amount of the mixed alcohol used is 2 to 20 moles, the amount of the epoxy compound used is 1 to 30 moles, the amount of the titanium compound used is 0.05 to 1.5 moles, and the amount of titanium tetrachloride used is 0.5 to 15 moles.

[0063] Example 1

[0064] (1) Vector preparation

[0065] In N 2 Under protective conditions, 10 g MgCl was added into a 250 ml three-necked flask. 2, 160 mg galactose, 1.6 g PVP and a certain amount of mixed alcohol (MgCl 2 : ethanol: n-butanol: isooctyl alcohol (molar ratio) = 1:3:7:2), stirring speed of 600rpm, heating to reaction temperature 70°C, wait until all solids are dissolved, and continue to react for 1h. Slowly add 30ml of epichlorohydrin by microinjection pump, and white to light yellow solids gradually precipitate during the addition process. After 1h of addition, react again for 1h, and then stop the reaction. After standing, remove the supernatant, wash with n-hexane 3 times, and vacuum dry at room temperature for 4h to obtain the carrier (white powder).

[0066] (2) Catalyst preparation

[0067] Take 3g of the obtained carrier and disperse it in a 100ml three-necked flask containing 50ml of methyl silicone oil; under nitrogen protection, place the flask in a constant temperature bath at -20℃ and stir mechanically (120rpm) to ensure that the carrier is evenly dispersed in the system; after stirring for 30min and the system drops to a lower temperature, add 0.75ml of tetrabutyl titanate dropwise using a microinjection pump for 1h; after the addition is completed, heat to 60℃ with stirring at a heating rate of 0.5℃ / min and continue to react for 2h. After the reaction is completed, let it stand and remove the supernatant, wash it with n-hexane 3 times, and vacuum dry it at room temperature for 4h to obtain a pretreated carrier.

[0068] Take 1g of the obtained pretreated carrier and disperse it in a 100ml three-necked flask containing 50ml of methyl silicone oil; under nitrogen protection, place the flask in a constant temperature bath at -15℃, during which mechanical stirring (60rpm) is performed; after stirring for 30min and the system drops to a lower temperature, add 12.5ml of TiCl dropwise 4 After the addition was completed, the mixture was heated to 90°C at a heating rate of 0.5°C / min while stirring and the reaction was continued for 2h. The methyl silicone oil and unreacted TiCl 4 , wash with 300 ml of n-hexane three times; put it back in a -15℃ constant temperature bath for 30 min, and repeat the above TiCl 4 The steps of dropping, heating, reacting, and washing are as follows; after washing, the catalyst is dried under vacuum at room temperature for 4 hours to obtain a spherical catalyst with a titanium content of 9.1 wt%. The catalyst has a spherical morphology as shown in FIG. Figure 1 As shown, the average particle size is 42.74 μm and the particle size distribution is uniform. Figure 2 shown.

[0069] (3) Ethylene polymerization

[0070] The spherical catalyst prepared above was used to carry out ethylene polymerization experiment in a 1L reactor; the solvent was n-heptane, the reaction temperature was 70°C, the spherical catalyst and the co-catalyst TEA were added according to the Al / Ti molar ratio of 100, the polymerization time was 1h, the polymerization pressure was 4bar, the polymerization activity was 10134g PE / g Cat, and the weight average molecular weight (M w ) is 100×10 4 g / mol, molecular weight distribution (MWD) is 4.0, and the bulk density of polymer particles is as high as 0.31 g / cm -3 The polymer particles have a relatively regular spherical morphology. Figure 3 As shown, the average particle size is 1040 μm and the particle size distribution is uniform. Figure 4 The sphericity results are shown in Figure 5 , the average sphericity is as high as 0.911.

[0071] Example 2

[0072] The preparation of the carrier and the catalyst was the same as in Example 1. The polymerization of ethylene was the same as in Example 1 except that 10 mL of 1-hexene was added. The polymerization activity was 16214 g PE / g Cat, which was 60% higher than that in Example 1. The insertion rate of 1-hexene in the polymer product was as high as 11.4 mol‰. The M w 82.9×10 4 g / mol, MWD was 5.7, and the characterization results of other polymerization products were close to those in Example 1.

[0073] Example 3

[0074] The preparation of the carrier and catalyst was the same as in Example 1. The ethylene polymerization was the same as in Example 1 except that the additional hydrogen was 3 bar. The polymerization activity decreased by 80% compared with that in Example 1, and the molecular weight of the polymerization product could be reduced to 17% of that of the homopolymer (16.76×10 4 g / mol), the hydrogen adjustment effect was significant, and the characterization results of other polymerization products were close to those in Example 1.

[0075] Example 4

[0076] The preparation of the carrier was the same as in Example 1 except that galactose was not added. The preparation of the catalyst and the ethylene polymerization were the same as in Example 1. The particle size distribution of the catalyst was uneven, with a tail in the direction of the small particle size (about 1 μm). Figure 6 The polymerization activity was 5000 gPE / g Cat, the product contained serious fine powder and had low sphericity.

[0077] Example 5

[0078] The preparation of the carrier was the same as in Example 1 except that galactose was replaced by fructose, and the preparation of the catalyst and ethylene polymerization were the same as in Example 1. The characterization results of the catalyst and the polymerization product were similar to those in Example 1.

[0079] Example 6

[0080] The preparation of the catalyst was the same as in Example 1 except that the methyl silicone oil was replaced with white oil, and the preparation of the carrier and the ethylene polymerization were the same as in Example 1. The characterization results of the catalyst and the polymerization product were similar to those in Example 1.

[0081] Example 7

[0082] The preparation of the catalyst was the same as in Example 1 except that the methyl silicone oil was replaced with n-heptane, and the preparation of the carrier and the ethylene polymerization were the same as in Example 1. The catalyst was not successfully prepared in a spherical morphology, and fine powder was serious in the polymer product, and the bulk density of the polymer product was low.

[0083] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A spherical catalyst for olefin polymerization, characterized in that: The catalyst is prepared by the following steps: (1) reacting a magnesium compound with an organic compound containing active hydrogen at 30-160° C. in the presence of polyvinyl pyrrolidone and a multipolar functional group compound to form a complex solution; (2) reacting the complex solution with an epoxy compound to precipitate a solid compound; The epoxy compound is shown in the general formula (I): In the general formula (I), R2 and R3 are each independently selected from hydrogen, a C1-C5 straight chain or branched alkyl group, wherein the hydrogen on the alkyl group may be optionally replaced by a halogen atom X; (3) washing the solid compound obtained in step (2) with an inert alkane solvent to obtain a spherical carrier of magnesium compound; (4) dispersing the magnesium compound spherical carrier obtained in step (3) in a high-viscosity inert hydrocarbon solvent, and adding a titanium compound at a low temperature of -40 to 0° C. to react to obtain an intermediate product; The titanium compound is shown in the general formula (II): In the general formula (II), R1', R2', R3', and R4' are each independently selected from C1-C 10 The alkyl group; (5) dispersing the intermediate product in a high-viscosity inert hydrocarbon solvent, adding titanium tetrachloride at a low temperature of -40 to 0°C to react with the intermediate product, and washing the solid product with an inert alkane solvent to obtain a spherical catalyst; The spherical catalyst, per mole of magnesium, the amount of polyvinyl pyrrolidone used is 0.001 to 0.1 mole, the amount of the multipolar functional group compound used is 0.002 to 0.2 mole, the amount of the organic compound containing active hydrogen is 2 to 20 moles, the amount of the epoxy compound is 1 to 30 moles, the amount of the titanium compound is 0.05 to 1.5 moles, and the amount of titanium tetrachloride is 0.5 to 15 moles; The multipolar functional group compound in step (1) is a mixture of one or more of glucose, fructose, sorbitol, galactose and cyclohexanehexol; The organic compound containing active hydrogen in step (1) is a compound of the general formula R(OH): m A compound or a mixture of compounds as shown, wherein R is C1-C 20 Hydrocarbon group, m≥1; The inert alkane solvent described in step (3) is a solvent of the general formula C n H 2n+2 A mixture of one or more compounds as shown, wherein n≥5; The high-viscosity inert hydrocarbon solvent described in step (4) and step (5) is a mixture of one or more of decane, white oil, methyl silicone oil and vaseline oil.

2. The spherical catalyst according to claim 1, characterized in that The magnesium compound described in step (1) is a mixture of one or more of magnesium halide, phenoxymagnesium chloride, isopropoxymagnesium chloride and butoxymagnesium chloride.

3. The spherical catalyst according to claim 1, characterized in that R(OH) in step (1) m A mixture of two or three selected from methanol, ethanol, propanol, n-butanol, isobutanol, pentanol, n-hexanol, 2-ethylhexanol, ethylene glycol, propylene glycol and glycerol.

4. The spherical catalyst according to claim 1, characterized in that The epoxy compound described in step (2) is ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epichlorohydrin, epibromohydrin or epibromobutylene.

5. The spherical catalyst according to claim 1, characterized in that The inert alkane solvent described in step (3) is selected from a mixture of one or more of n-hexane, cyclohexane, n-heptane, n-octane and n-nonane.

6. The spherical catalyst according to claim 1, characterized in that The low temperature described in step (4) and step (5) refers to -20 to -10°C.

7. Use of a polymerization catalyst system comprising the spherical catalyst component according to any one of claims 1 to 6 in alpha-olefin polymerization.

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