Metal-silane composite catalyst, its preparation method and application

Abstract

The present application relates to the field of olefin polymerization catalyst, and provides a metal-silane composite catalyst and a preparation method and application thereof.The metal-silane composite catalyst comprises a mixture of diazabicycloalkyldialkoxy silane compounds, organic compounds containing C-O and / or C=O, metal halides and / or reaction products of the above components, and further comprises superfine inorganic oxide; after mixing the metal-silane composite catalyst and organic aluminum compound, the mixture can be used for olefin polymerization reaction.The polymer prepared by using the catalyst has a high melt index and low oligomer content.

Description

A metal-silane composite catalyst, its preparation method and application Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to a metal-silane composite catalyst and its preparation method, as well as the preparation of an olefin polymerization catalyst from the metal-silane composite catalyst and its use in olefin polymerization reactions. Background Technology

[0002] Catalyst components in the homopolymerization or copolymerization of olefins affect the properties of the polymer. During the polymerization of ethylene, catalysts generate oligomers, which alter the intermolecular forces in polyethylene, affecting the product's performance in use and processing, including yield strength, elongation, and rigidity. The amount of oligomers is generally measured by the amount of hexane extract; therefore, the amount of hexane extract is also an important indicator of catalyst performance.

[0003] Chinese patent CN101173015A discloses a catalyst component for ethylene polymerization or copolymerization, which is a titanium-containing solid supported on at least one transition metal titanium compound and at least one electron-donating compound. Its characteristic is that it is a titanium-containing solid supported on at least one transition metal titanium compound and at least one electron-donating compound; the general formula of the transition metal titanium compound is Ti(OR). a X b In the formula, R is a C1-C14 aliphatic or aromatic hydrocarbon group, X is a halogen, a is an integer from 0 to 2, b is an integer from 0 to 4, and a+b=3 or 4; the electron donor compound is selected from aliphatic ethers, cyclic aliphatic ethers, or aliphatic ketones. This catalyst exhibits high catalytic activity, strong copolymerization ability, high polymer bulk density, and low fine particle size, making it suitable for slurry polymerization or gas-phase polymerization of ethylene. However, in industrial applications, this catalyst generates a relatively large amount of fine powder, which is detrimental to equipment operation.

[0004] Chinese patent CN100389134A discloses a catalyst component for ethylene polymerization or copolymerization. It comprises a magnesium / titanium-containing solid with at least one transition metal titanium compound supported on it, at least one suitable electron donor, and at least one hydrogen-modifying agent. The catalyst containing this component exhibits excellent hydrogen-modifying sensitivity, high catalytic activity, good catalyst-polymer particle morphology, and low fine powder content. It is highly suitable for ethylene slurry and gas-phase polymerization processes, especially for the production of ethylene polymers with a wide molecular weight distribution using a dual-reactor system. Its key feature is that it comprises a catalyst component obtained by supporting at least one transition metal titanium compound, at least one electron donor, and at least one hydrogen-modifying agent on a titanium / magnesium-containing solid; the electron donor is an aliphatic ether, aromatic ether, cyclic aliphatic ether, or aliphatic ketone; the general formula of the transition metal titanium compound is Ti(OR). a X b In the formula, R is a C1-C14 aliphatic or aromatic hydrocarbon group, X is a halogen atom, a is an integer from 0 to 2, b is an integer from 0 to 4, and a+b=3 or 4; the hydrogen-modified performance improver is silicon tetrachloride. This scheme reduces the oligomer content in the polymer, but the catalyst activity is not high enough.

[0005] Chinese patent CN112812205A discloses a catalyst component for olefin polymerization, the catalyst itself, its preparation method, and its application, particularly suitable for gas-phase fluidized bed processes. The catalyst component comprises catalyst component 1 and catalyst component 2; wherein catalyst component 1 contains: 1) an ultrafine inorganic oxide support, and 2) reaction and coordination products of magnesium halides, titanium halides, electron donor compounds, and nitrogen-oxygen heterocyclic compounds; catalyst component 2 is a heterocyclic compound containing S atoms. The catalyst comprises reaction products of the following components: (A) the catalyst component described in this invention; and (B) a compound with the general formula AlR d X 3-d The catalyst of this invention exhibits high activity in the field of gas-phase polymerization, resulting in polymers with higher bulk density. More importantly, it demonstrates excellent copolymerization performance, providing a foundation for improving the production stability of gas-phase fluidized beds and developing new products.

[0006] Therefore, there is an urgent need to develop a catalyst for olefin polymerization that has higher activity and melt index, and low oligomer content in the polymer. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a metal-silane composite catalyst for olefin polymerization. The composite catalyst comprises ultrafine inorganic oxides, a main catalytic component (a diazacyclodialkoxysilane compound, an organic compound containing CO and / or C=O, and a metal-silane complex resulting from a metal halide reaction), and is activated by the composite catalyst component and an organoaluminum compound for olefin polymerization.

[0008] One objective of this invention is to provide a metal-silane composite catalyst comprising: a diazacyclodialkoxysilane compound, an organic compound containing CO and / or C=O, a mixture of metal halides, and / or the reaction products of the above components, wherein the metal halides include titanium halides and magnesium halides.

[0009] According to the present invention, in the metal-silane composite catalyst:

[0010] The general formula of the diazacyclic diekoxysilane compounds is (RO)2Si(NC n H 2n )2, where -NC n H 2n The radical is a nitrogen-containing heterocyclic group, where n is an integer from 3 to 10, preferably 4 or 5; R is selected from C1-C8 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C10 cycloalkyl or C6-C12 aryl, preferably from C1-C5 alkyl, C3-C8 cycloalkyl or C6-C10 aryl; specifically, the diazacyclic diekoxysilane compound is selected from at least one of piperidinyldiethoxysilane, piperidinyldimethoxysilane, and dipyrrolithyldiethoxysilane;

[0011] The organic compound containing CO and / or C=O is selected from at least one of esters, ethers, and ketones, preferably from at least one of alkyl esters of C1-C8 saturated fatty carboxylic acids, alkyl esters of C7-C12 aromatic carboxylic acids, C2-C10 fatty ethers, C3-C8 cyclic ethers, and C3-C8 saturated fatty ketones; specifically, the organic compound containing CO and / or C=O is selected from at least one of methyl formate, ethyl formate, isopropyl formate, n-propyl formate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, diethyl ether, propyl ether, hexyl ether, tetrahydrofuran, acetone, and methyl isobutyl ketone, preferably from at least one of methyl formate, ethyl acetate, n-butyl acetate, diethyl ether, hexyl ether, tetrahydrofuran, acetone, and methyl isobutyl ketone, more preferably tetrahydrofuran;

[0012] The magnesium halide can be a common magnesium halide compound, for example, the magnesium halide is selected from at least one of magnesium chloride, magnesium bromide and magnesium iodide;

[0013] The titanium halide can be a common titanium halide compound, for example, the titanium halide is selected from at least one of titanium trichloride, titanium tetrachloride, titanium tribromide, and titanium tetrabromide, preferably from at least one of titanium trichloride and titanium tetrachloride;

[0014] The metal-silane composite catalyst further includes ultrafine inorganic oxides. Specifically, the ultrafine inorganic oxides are selected from at least one of ultrafine alumina and ultrafine silica, preferably ultrafine silica. The particle size of the ultrafine inorganic oxides is 0.01–10 μm, preferably 0.01–5 μm, and more preferably 0.01–2 μm. Based on the total weight of the metal-silane composite catalyst being 100 wt%, the ultrafine inorganic oxides account for 5–40 wt%, preferably 10–35 wt%, and more preferably 15–30 wt%.

[0015] According to the present invention, in the metal-silane composite catalyst:

[0016] Based on a total weight of 100 wt% for the metal-silane composite catalyst, the titanium content is 0.2–5.5 wt%, preferably 0.5–3.0 wt%, and more preferably 1.8–2.5 wt%.

[0017] Based on each mol of titanium, the diazacyclodialkoxysilane compound is 0.02–12 mol, preferably 0.1–10 mol, more preferably 0.1–5 mol; the organic compound containing CO and / or C=O is 1–550 mol, preferably 25–350 mol, more preferably 120–250 mol; and the magnesium halide is 0.3–12 mol, preferably 1–10 mol, more preferably 1–8 mol.

[0018] The second objective of this invention is to provide a method for preparing the above-mentioned metal-silane composite catalyst, comprising: reacting components including a diazacyclodialkoxysilane compound, an organic compound containing CO and / or C=O, and a metal halide to obtain the metal-silane composite catalyst.

[0019] According to the present invention, the preparation method of the metal-silane composite catalyst specifically includes the following steps:

[0020] (a) After stirring and reacting the components including the diazacyclodialkoxysilane compound, the organic compound containing CO and / or C=O, titanium halide and magnesium halide, a composite catalyst mother liquor is obtained.

[0021] (b) The ultrafine inorganic oxide is added to the mother liquor of the composite catalyst and mixed to obtain a slurry;

[0022] (c) After spray drying the slurry, the metal-silane composite catalyst is obtained.

[0023] According to an embodiment of the present invention, in the preparation method of the metal-silane composite catalyst:

[0024] The reaction conditions in step (a) are: a reaction temperature of 55–85°C and a reaction time of 2–3.5 h;

[0025] The ultrafine inorganic oxides mentioned in step (b) can be added to the composite catalyst in solid form or in dispersion form, such as commercially available silica gel products.

[0026] In step (b), the content of ultrafine inorganic oxides should be sufficient to form a slurry suitable for spray drying after mixing with the mother liquor. Preferably, the content of ultrafine inorganic oxides in the slurry is 1-45 wt%, and more preferably 5-30 wt%.

[0027] In step (c), the spray drying can be carried out using spray drying equipment and conditions commonly used in the prior art. Specifically, the spray drying conditions include: an inlet temperature of 90-220°C, preferably 110-200°C; and an outlet temperature of 70-110°C, preferably 95-110°C.

[0028] A third objective of this invention is to provide the above-mentioned metal-silane composite catalyst or the metal-silane composite catalyst obtained by the above preparation method for use in the preparation of olefin polymerization catalysts.

[0029] The fourth objective of this invention is to provide an olefin polymerization catalyst, comprising: an organoaluminum compound, and the above-mentioned metal-silane composite catalyst or a metal-silane composite catalyst obtained by the above preparation method.

[0030] According to the present invention, in the olefin polymerization catalyst:

[0031] The general formula of the organoaluminum compound is A1R. n X 3-n In the general formula, R is a C1-C18 straight-chain or branched alkyl group, X is a halogen, and 0 < n ≤ 3; preferably, the organoaluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and diethylaluminum chloride.

[0032] The molar ratio of aluminum in the organoaluminum compound to titanium in the metal-silane composite catalyst is (3-4500):1, preferably (12-1800):1.

[0033] To make the solid catalyst component obtained after spray drying suitable for the production of ethylene polymers, the organoaluminum compound acting as the activator component must reduce the titanium atoms in the catalyst component to a state that allows for the effective polymerization of ethylene. Generally, the catalyst component and the activator component are reacted in a hydrocarbon solvent to obtain a catalyst capable of olefin polymerization; alternatively, the catalyst component and the activator component can be reacted in a hydrocarbon solvent during polymerization to further initiate the olefin polymerization reaction. The hydrocarbon solvents include, but are not limited to, isopentane, hexane, heptane, toluene, xylene, naphtha, and mineral oil.

[0034] The fifth objective of this invention is to provide the above-mentioned olefin polymerization catalyst for use in olefin polymerization reactions, specifically, it can be used in olefin homopolymerization or copolymerization reactions.

[0035] The catalyst of this invention is suitable for homopolymerization of various ethylenes or copolymerization of ethylene with α-olefins, wherein the α-olefins can be selected from propylene, butene, pentene, hexene, octene, and 4-methylpentene-1. The polymerization process can employ gas-phase, slurry, and solution polymerization methods, with gas-phase fluidized bed polymerization being particularly suitable. The conditions for olefin polymerization can be conventionally selected according to existing technologies and will not be elaborated upon here.

[0036] This invention provides a metal-silane composite catalyst, comprising a mixture of components such as diazacyclodialkoxysilane compounds, organic compounds containing CO and / or C=O, metal halides, and ultrafine inorganic oxides, and / or their reaction products. This composite catalyst is used as an olefin polymerization catalyst. Using ultrafine inorganic oxides as a support, a mother liquor prepared by reacting organic compounds containing CO and / or C=O, magnesium halides, diazacyclodialkoxysilane compounds, and titanium halides is mixed with the support. Finally, the catalyst component is obtained by spray molding. The addition of an organoaluminum compound yields a highly active olefin polymerization catalyst. Polymers produced using this olefin polymerization catalyst exhibit a high melt index, low hexane extract, and low oligomer content.

[0037] The diazacyclic diekoxysilane compounds used in this invention are silane compounds containing alkoxy groups. The alkoxy groups exhibit a strong electron-donating effect, allowing silicon atoms to coordinate with the active center and effectively improve the polymerization efficiency of the catalyst's active center. Furthermore, the diazacyclic diekoxysilane compounds have a significant steric effect, which can improve the hydrogen sensitivity of the polymerization and enhance catalytic efficiency. In actual polymerization reactions, under the same polymerization conditions, the catalyst system containing diazacyclic groups can increase the polymerization activity of the catalyst and the melt index of the prepared polymer while reducing the hexane extractable content. Detailed Implementation

[0038] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0039] The testing instruments and conditions used in this embodiment are as follows:

[0040] 1. Catalyst activity: expressed as the weight of polyethylene resin obtained per gram of catalyst;

[0041] 2. Polymer melt index (MI): Model 6932 melt indexer, CEAST, Italy;

[0042] 3. Hexane extractable content (wt%) in polymer powder: The dried polymer powder is extracted with hexane. Specifically, the polymer is washed with hexane for 4 hours. The percentage of the weight difference of the polymer powder before and after extraction relative to the weight of the polymer powder before extraction is the hexane extractable content in the polymer powder.

[0043] 4. Determination of titanium content in catalyst components: Dissolve the catalyst sample in 1M sulfuric acid, measure the solution using a spectrophotometer, and calculate the titanium content using the working curve.

[0044] 5. The content of ultrafine inorganic oxides can be obtained by calculating the ratio of the feed amount to the mass of the produced catalyst.

[0045] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0046] Example 1

[0047] (1) Preparation of metal-silane composite catalysts

[0048] 1.5 g TiCl4, 4.0 g anhydrous MgCl2, 1.9 g dipiperidinyldiethoxysilane and 100 mL tetrahydrofuran were added sequentially to a 250 mL three-necked flask purged with nitrogen. The mixture was stirred and heated to 65 °C, and reacted at this temperature for 3 hours. The mixture was then cooled to 35 °C to obtain the mother liquor.

[0049] 6g of silica gel (Cabot Corporation TS-610, particle size 0.02-0.1μm) was added to a 250mL three-necked flask purged with nitrogen. The cooled mother liquor was then added, and the temperature was maintained at 35℃. After stirring for 1 hour, the mother liquor mixed with silica gel was spray-dried using a spray dryer under the following conditions: inlet temperature 195℃ and outlet temperature 110℃. The resulting catalyst composition contained 2.37wt% titanium and 23wt% silica.

[0050] (2) Ethylene slurry polymerization

[0051] 1L of hexane was added to a 2L polymerization reactor purged with nitrogen, along with 2mL of 1M triethylaluminum / hexane solution and 0.01g of the metal-silane composite catalyst component obtained in step (1). The temperature was raised to 75℃, and hydrogen gas at 0.18MPa was added. After hydrogenation, ethylene gas at 0.75MPa was added, and the temperature was raised to 85℃. After reacting for 2 hours, the mixture was cooled and discharged. The polymerization results are shown in Table 1.

[0052] Example 2

[0053] (1) Preparation of metal-silane composite catalysts

[0054] Same as Example 1.

[0055] (2) Ethylene slurry polymerization

[0056] Same as Example 1, except that 0.05g of the metal-silane composite catalyst component obtained in step (1) was added, the temperature was raised to 75°C and 0.68 MPa of hydrogen was added, and after the hydrogenation was completed, 0.35 MPa of ethylene was added. The polymerization results are shown in Table 1.

[0057] Example 3

[0058] (1) Preparation of catalyst system

[0059] Same as Example 1, except that the reaction temperature was adjusted to 85°C, the reaction time was adjusted to 4 hours, and the titanium content of the obtained catalyst component was 2.35 wt% and the silicon dioxide content was 22 wt%.

[0060] (2) Ethylene slurry polymerization

[0061] Same as in Example 1, the polymerization results are shown in Table 1.

[0062] Example 4

[0063] (1) Preparation of catalyst system

[0064] Same as Example 1, except that: the spray inlet temperature is adjusted to 170°C, the outlet temperature is 100°C, and the titanium content of the obtained catalyst component is 2.25 wt% and the silica content is 21 wt%.

[0065] (2) Ethylene slurry polymerization

[0066] Same as in Example 1, the polymerization results are shown in Table 1.

[0067] Example 5

[0068] (1) Preparation of metal-silane composite catalysts

[0069] Same as Example 1, except that: the amount of dipiperidinyldiethoxysilane used is 3.8g, the titanium content of the obtained catalyst component is 2.45wt%, and the silicon dioxide content is 24wt%.

[0070] (2) Ethylene slurry polymerization

[0071] Same as Example 1, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0072] Example 6

[0073] (1) Preparation of metal-silane composite catalysts

[0074] Same as Example 3.

[0075] (2) Ethylene slurry polymerization

[0076] Same as Example 2, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0077] Example 7

[0078] (1) Preparation of metal-silane composite catalysts

[0079] Same as Example 1, except that the amount of dipiperidinyldiethoxysilane used is 1.0 g, the titanium content of the obtained catalyst component is 2.18 wt%, and the silicon dioxide content is 24 wt%.

[0080] (2) Ethylene slurry polymerization

[0081] Same as Example 1, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0082] Example 8

[0083] (1) Preparation of metal-silane composite catalysts

[0084] Same as Example 5.

[0085] (2) Ethylene slurry polymerization

[0086] Same as Example 2, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0087] Example 9

[0088] (1) Preparation of metal-silane composite catalysts

[0089] Same as Example 1, except that dipiperidinyldiethoxysilane is replaced with dipyrrolidinyldiethoxysilane in an amount of 0.9 g, and the resulting catalyst component has a titanium content of 2.20 wt% and a silica content of 23 wt%.

[0090] (2) Ethylene slurry polymerization

[0091] Same as Example 1, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0092] Example 10

[0093] (1) Preparation of metal-silane composite catalysts

[0094] Same as Example 7.

[0095] (2) Ethylene slurry polymerization

[0096] Same as Example 2, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0097] Example 11

[0098] (1) Preparation of metal-silane composite catalysts

[0099] Same as Example 1, except that dipiperidinyldiethoxysilane is replaced with dipiperidinyldiethoxysilane in an amount of 0.9 g, and the resulting catalyst component has a titanium content of 2.32 wt% and a silica content of 22 wt%.

[0100] (2) Ethylene slurry polymerization

[0101] Same as Example 1, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0102] Example 12

[0103] (1) Preparation of metal-silane composite catalysts

[0104] Same as Example 9.

[0105] (2) Ethylene slurry polymerization

[0106] Same as Example 2, except that the metal-silane composite catalyst obtained in step (1) above was added. The polymerization results are shown in Table 1.

[0107] Comparative Example 1

[0108] (1) Preparation of catalyst components

[0109] 1.5 g TiCl4, 4.0 g anhydrous MgCl2 and 100 mL tetrahydrofuran were added to a 250 mL three-necked flask purged with nitrogen. The mixture was stirred and heated to 65 °C. The mixture was then kept at this temperature for 3 hours and cooled to 35 °C to obtain the mother liquor.

[0110] 6g of silica gel (Cabot Corporation TS-610, particle size 0.02-0.1μm) was added to a 250mL three-necked flask purged with nitrogen. The cooled mother liquor was then added, and the temperature was maintained at 35℃. After stirring for 1 hour, the mother liquor mixed with silica gel was spray-dried using a spray dryer under the following conditions: inlet temperature 195℃ and outlet temperature 110℃. The resulting catalyst composition contained 2.2wt% titanium and 25wt% silica.

[0111] (2) Ethylene slurry polymerization

[0112] 1L of hexane was added to a 2L polymerization reactor purged with nitrogen, along with 2mL of 1M triethylaluminum / hexane and 0.01g of catalyst. The temperature was raised to 75℃, and hydrogen gas was added at 0.18MPa. After hydrogenation, ethylene gas at 0.75MPa was added, and the temperature was raised to 85℃. After reacting for 2 hours, the mixture was cooled and discharged. The polymerization results are shown in Table 1.

[0113] Comparative Example 2

[0114] (1) Preparation of catalyst components

[0115] Same as Comparative Example 1.

[0116] (2) Ethylene slurry polymerization

[0117] Similar to Comparative Example 1, except that 0.05g of catalyst was added, the temperature was raised to 75℃ and hydrogen gas at 0.68MPa was added, and ethylene gas at 0.35MPa was added after hydrogenation. The polymerization results are shown in Table 1.

[0118] Table 1. Catalyst performance obtained from examples and comparative examples

[0119]

[0120] As shown in Table 1, under the same polymerization conditions, compared with Comparative Example 1, the catalysts in Examples 1, 3-5, 7, 9, and 11 of this invention exhibit higher activity and better hydrogen sensitivity; the resulting polymers have higher melt indexes and lower hexane extractable content. When polymerizing under high hydrogen conditions, the resulting resin has a lower molecular weight and is not used for hexane extractable determination. Under the same high hydrogen conditions, compared with Comparative Example 2, the catalysts in Examples 2, 6, 8, 10, and 12 of this invention also exhibit higher catalytic activity.

[0121] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A metal-silane composite catalyst, comprising: The mixture of diazacyclodialkoxysilane compounds, organic compounds containing CO and / or C=O, metal halides, and / or reaction products of the above components, wherein the metal halides include titanium halides and magnesium halides, and the organic compounds containing CO and / or C=O are selected from at least one of methyl formate, ethyl formate, isopropyl formate, n-propyl formate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, diethyl ether, propyl ether, hexyl ether, tetrahydrofuran, acetone, and methyl isobutyl ketone; based on per mol of titanium, the diazacyclodialkoxysilane compound is 0.1-5 mol, the organic compounds containing CO and / or C=O are 120-250 mol, and the magnesium halides are 1-8 mol.

2. The metal-silane composite catalyst according to claim 1, characterized in that, The general formula of the diazacyclic diekoxysilane compounds is (RO)2Si(NC n H 2n )2, where -NC n H 2n The nitrogen heterocyclic group is n, which is an integer from 3 to 10; R is selected from C1 to C8 alkyl, C2 to C6 alkenyl, C2 to C6 alkynyl, C3 to C10 cycloalkyl or C6 to C12 aryl; and / or, the magnesium halide is selected from at least one of magnesium chloride, magnesium bromide, and magnesium iodide; and / or, the titanium halide is selected from at least one of titanium trichloride, titanium tetrachloride, titanium tribromide, and titanium tetrabromide; and / or, the metal-silane composite catalyst further includes ultrafine inorganic oxides.

3. The metal-silane composite catalyst according to claim 2, characterized in that, The general formula of the diazacyclic diekoxysilane compounds is (RO)2Si(NC n H 2n )2, where -NC n H 2n It is a nitrogen heterocyclic group, n is 4 or 5; R is selected from C1~C5 alkyl, C3~C8 cycloalkyl or C6~C10 aryl; and / or, the titanium halide is selected from at least one of titanium trichloride and titanium tetrachloride.

4. The metal-silane composite catalyst according to claim 2, characterized in that, The diazacyclodialkoxysilane compound is selected from at least one of piperidinyldiethoxysilane, piperidinyldimethoxysilane, and dipyrrolithyldiethoxysilane; and / or, the organic compound containing CO and / or C=O is selected from at least one of methyl formate, ethyl acetate, n-butyl acetate, diethyl ether, hexyl ether, tetrahydrofuran, acetone, and methyl isobutyl ketone; and / or, the ultrafine inorganic oxide is selected from at least one of ultrafine alumina and ultrafine silica; and / or, the particle size of the ultrafine inorganic oxide is 0.01~10 μm; and / or, based on the total weight of the metal-silane composite catalyst being 100 wt%, the ultrafine inorganic oxide is 5~40 wt%.

5. The metal-silane composite catalyst according to claim 4, characterized in that, The particle size of the ultrafine inorganic oxide is 0.01~5μm; and / or, based on the total weight of the metal-silane composite catalyst being 100wt%, the ultrafine inorganic oxide is 10~35wt%.

6. The metal-silane composite catalyst according to claim 5, characterized in that, The particle size of the ultrafine inorganic oxide is 0.01~2μm; and / or, based on the total weight of the metal-silane composite catalyst being 100wt%, the ultrafine inorganic oxide is 15~30wt%.

7. The metal-silane composite catalyst according to claim 1, characterized in that, Based on a total weight of 100 wt% for the metal-silane composite catalyst, the titanium content is 0.2~5.5 wt%.

8. The metal-silane composite catalyst according to claim 7, characterized in that, Based on a total weight of 100 wt% for the metal-silane composite catalyst, the titanium content is 0.5 to 3.0 wt%.

9. A method for preparing the metal-silane composite catalyst according to any one of claims 1 to 8, comprising: The metal-silane composite catalyst is obtained by reacting components including diazacyclodialkoxysilane compounds, organic compounds containing CO and / or C=O, and metal halides.

10. The preparation method according to claim 9, characterized in that, The preparation method specifically includes the following steps: (a) stirring and reacting the components including the diazacyclodialkoxysilane compound, organic compounds containing CO and / or C=O, titanium halide and magnesium halide to obtain a composite catalyst mother liquor; (b) adding ultrafine inorganic oxides to the composite catalyst mother liquor and mixing to obtain a slurry; (c) spray drying the slurry to obtain the metal-silane composite catalyst.

11. The preparation method according to claim 10, characterized in that, The reaction conditions in step (a) are: a reaction temperature of 55~85℃ and / or a reaction time of 2~3.5h; and / or the content of ultrafine inorganic oxides in the slurry of step (b) is 1~45wt%; and / or the spray drying conditions in step (c) include: an inlet temperature of 90~220℃ and / or an outlet temperature of 70~110℃.

12. The preparation method according to claim 11, characterized in that, The content of ultrafine inorganic oxides in the slurry of step (b) is 5~30wt%; and / or, the spray drying conditions in step (c) include: an inlet temperature of 110~200℃; and / or, an outlet temperature of 95~110℃.

13. A metal-silane composite catalyst according to any one of claims 1 to 8 or a metal-silane composite catalyst obtained by the preparation method according to any one of claims 9 to 12, for use in preparing an olefin polymerization catalyst.

14. An olefin polymerization catalyst, comprising: Organoaluminum compounds, and the metal-silane composite catalyst according to any one of claims 1 to 8, or the metal-silane composite catalyst obtained by the preparation method according to any one of claims 9 to 12.

15. The olefin polymerization catalyst according to claim 14, characterized in that, The general formula of the organoaluminum compound is A1R. n X 3-n In the general formula, R is a C1-C18 straight-chain or branched alkyl group, X is a halogen, 0 < n ≤ 3; and / or, the molar ratio of aluminum in the organoaluminum compound to titanium in the metal-silane composite catalyst is (3~4500):

1.

16. The olefin polymerization catalyst according to claim 15, characterized in that, The organoaluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, and diethylaluminum chloride; and / or, the molar ratio of aluminum in the organoaluminum compound to titanium in the metal-silane composite catalyst is (12~1800):

1.

17. An olefin polymerization catalyst according to any one of claims 14 to 16 for use in olefin polymerization reactions.

Images