阅读说明：本技术 一种改性烷基铝氧烷、制备方法及用于聚烯烃聚合反应的催化剂 (Modified alkylaluminoxane, preparation method and catalyst for polyolefin polymerization reaction ) 是由 毛菀钰 赵志鹏 赵小平 于 2020-06-19 设计创作，主要内容包括：本发明提供了一种改性烷基铝氧烷、制备方法及用于聚烯烃聚合反应的催化剂,所述制备方法包括以下步骤：将含有烷基铝的溶液A分为m股,含有碳氧键化合物的溶液B分为n股后,将溶液A的m股与溶液B的n股接触反应得到烷基铝氧烷前体,再将烷基铝氧烷前体后处理,得到烷基铝氧烷,经与二氧化硅反应后得到改性烷基铝氧烷；本发明提供的改性烷基铝氧烷制备方法,能够制备出低副产物、低烷基铝含量的用于烯烃聚合的固体颗粒状烷基铝氧烷助催化剂,且该助催化剂可直接用于部分单中心催化剂,不需要再使用其他载体,方便使用,应用价值高。(The invention provides a modified alkyl aluminoxane, a preparation method and a catalyst for polyolefin polymerization reaction, wherein the preparation method comprises the following steps: dividing a solution A containing alkyl aluminum into m strands, dividing a solution B containing a carbon-oxygen bond compound into n strands, then carrying out contact reaction on the m strands of the solution A and the n strands of the solution B to obtain an alkyl aluminoxane precursor, carrying out post-treatment on the alkyl aluminoxane precursor to obtain alkyl aluminoxane, and carrying out reaction on the alkyl aluminoxane precursor and silicon dioxide to obtain modified alkyl aluminoxane; the preparation method of the modified alkylaluminoxane provided by the invention can prepare the solid granular alkylaluminoxane cocatalyst which has low byproduct and low alkylaluminium content and is used for olefin polymerization, and the cocatalyst can be directly used for partial single-site catalyst, does not need to use other carriers, is convenient to use and has high application value.)

1. A preparation method of modified alkylaluminoxane is characterized by comprising the following steps: dividing the solution A containing the alkyl aluminum into m strands, dividing the solution B containing the carbon-oxygen bond compound into n strands, then carrying out contact reaction on the m strands of the solution A and the n strands of the solution B to obtain an alkyl aluminoxane precursor, carrying out post-treatment on the alkyl aluminoxane precursor to obtain alkyl aluminoxane, and carrying out reaction on the alkyl aluminoxane precursor and silicon dioxide to obtain modified alkyl aluminoxane.

2. The production method according to claim 1, wherein the solution a containing an aluminum alkyl is a solution of an aluminum alkyl or a solution of an aluminum alkyl precursor;

preferably, in the solution A containing the aluminum alkyl, the mass fraction of the aluminum alkyl is 1 to 70 percent;

preferably, the mass fraction of the aluminum alkyl is 40 to 60 percent.

3. The production method according to claim 1 or 2, wherein the alkyl aluminum includes one or a combination of at least two of trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, or tri-tert-butyl aluminum.

4. The production method according to any one of claims 1 to 3, wherein the mass fraction of the carbon-oxygen bond compound in the solution B containing the carbon-oxygen bond compound is 1% to 30%;

preferably, the mass fraction of the carbon-oxygen bond compound is 5 to 20 percent.

5. The method according to any one of claims 1 to 4, wherein the compound having a carbon-oxygen bond comprises any one or a combination of at least two of benzophenone, benzoic acid, boric acid, silaborane, alkyl boric acid, or boroxine;

preferably, the compound containing a carbon-oxygen bond is any one or a combination of at least two of benzophenone, benzoic acid, silaborane, methyl boric acid or trimethoxyboroxine.

6. The method according to any one of claims 1 to 5, wherein m and n are each an integer greater than 2;

preferably, the cross-sectional area of each flow channel in m of the solution A is 0.1-10 mm²；

Preferably, the cross-sectional area of each flow channel in the n of the solution B is 0.1-10 mm²。

7. The production method according to any one of claims 1 to 6, wherein the mass ratio of the alkyl aluminum in the solution A to the compound having a carbon-oxygen bond in the solution B is (0.1 to 2.0): 1;

preferably, the mass ratio is (0.5-1.4): 1;

preferably, the mass ratio is (0.8-1.2): 1;

preferably, the temperature of the contact reaction is 30-100 ℃, and preferably 50-80 ℃;

preferably, the method of post-treatment comprises one or a combination of at least two of aging, filtration, vacuum drying or distillation.

8. The method of any one of claims 1 to 7, wherein the method of reacting with silica comprises: mixing alkylaluminoxane with silicon dioxide and a solvent, stirring, filtering and drying to obtain modified alkylaluminoxane;

preferably, the solvent is toluene;

preferably, the stirring method comprises the following steps: stirring for 0.5-1 h at normal temperature, then heating to 80-120 ℃, and continuing stirring for 0.5-1 h;

preferably, the stirring is carried out under protection of a protective gas.

9. Modified alkylaluminoxanes prepared according to the process for the preparation according to anyone of claims 1 to 8.

10. A cocatalyst for use in a polyolefin polymerization reaction, wherein said cocatalyst comprises the modified alkylaluminoxane of claim 9.

Technical Field

The invention belongs to the field of olefin polymerization, and relates to modified alkylaluminoxane, a preparation method and a catalyst for polyolefin polymerization reaction.

Background

The single-site catalysts such as metallocene catalyst, constrained geometry catalyst, late transition metal catalyst, non-metallocene catalyst, etc. and alkyl aluminoxane and carrier together form a high-activity catalytic system for olefin polymerization. The development of the polyolefin industry is greatly promoted by the presence of alkylaluminoxanes. Currently, alkylaluminoxanes are generally prepared by hydrolysis and non-hydrolysis methods.

The hydrolysis method is to produce alkylaluminoxane by the reaction of alkylaluminum and water. The method can be divided into two categories, indirect hydrolysis and direct hydrolysis, according to the state of water for reaction. The direct hydrolysis method is a method in which water is added to a reaction system directly or carried by a carrier (such as an inert gas, a solvent, etc.) to directly react with an aluminum alkyl. Depending on the actual operation, there are a solvent dilution method, an inert gas carrier method, a steam condensation method, an ice water method and the like. Because the reaction of the aluminum alkyl with water is relatively violent, the reaction degree is difficult to control in a controllable and stable state, and a large amount of aluminum in the product is lost. The indirect hydrolysis method is to react inorganic salt containing crystal water or porous matter adsorbing water with alkyl aluminum. By using the indirect hydrolysis method, the loss of aluminum caused by overlarge water concentration also exists at the initial stage of adding the alkyl aluminum into the reaction system, and meanwhile, the proportion of the alkyl aluminum in the reaction product is large, so that the catalytic activity of the reaction on the polyolefin is greatly influenced. For example, CN111004265A discloses a method for preparing alkylaluminoxane, which adopts a method for preparing alkylaluminium, water and inert reaction medium, and this direct hydration method can achieve fast dispersion and mixing of materials, but still has the problems of difficult control of reaction degree and large loss of aluminium caused by violent reaction.

In order to avoid the problems of the hydrolysis method, several non-hydrolytic methods for preparing alkylaluminoxanes have been developed. The non-hydrolysis method is usually to provide the oxygen atom in the alkylaluminoxane by a compound containing a carbonyl group or a metal oxide. Compared with the hydrogen-oxygen bond of water, the chemical bond of the substances and the oxygen atom is weaker, so that the reaction condition of the non-hydrolysis method is milder and is relatively more controllable. Meanwhile, the proportion of unreacted aluminum alkyl in the reaction product is small. However, the non-hydrolysis method has complex reaction process, more side reactions and control of reaction degree, and the prevention of the generation of some byproducts which are difficult to separate is of great importance to the commercial application of the method.

For example, CN1112120A, etc. directly react with boroxine and a solution composed of alkyl aluminoxane and trialkyl aluminum to obtain a solid aluminumoxy compound composition, and CN107722146A, CN104968668A, etc. react with a composition containing polyalkylaluminoxane, trialkyl aluminum and a hydrocarbon solvent in a reaction kettle to obtain a solid polyaluminoxane composition, although the reaction conditions of these methods are relatively mild, the reaction degree cannot be well controlled, side reaction products are large, and the recovery rate of the polyaluminoxane composition as a solid product is not high, which is not suitable for commercial application.

Therefore, based on the existing problems, how to provide a method which can not only control the reaction conditions to be mild and reduce the generation of byproducts, but also reduce the content of aluminum alkyl, improve the yield of products and improve the catalytic activity of the solid alkylaluminoxane polymerization cocatalyst has important value for the application thereof.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a modified alkylaluminoxane, a preparation method and a catalyst for polyolefin polymerization reaction, so as to solve the problems of violent reaction conditions, difficult control, more byproducts, high product yield and low catalytic activity of the prepared alkylaluminoxane prepared by the existing method.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for preparing a modified alkylaluminoxane, comprising the steps of: dividing the solution A containing the alkyl aluminum into m strands, dividing the solution B containing the carbon-oxygen bond compound into n strands, then carrying out contact reaction on the m strands of the solution A and the n strands of the solution B to obtain an alkyl aluminoxane precursor, carrying out post-treatment on the alkyl aluminoxane precursor to obtain alkyl aluminoxane, and carrying out reaction on the alkyl aluminoxane precursor and silicon dioxide to obtain modified alkyl aluminoxane.

The preparation method of the modified alkylaluminoxane provided by the invention uses a non-hydrolysis method, and makes the reaction condition milder and controllable through the reaction of the solution of alkylaluminium and the compound containing a carbon-oxygen bond, and simultaneously uses a shunting form to carry out the reaction, thereby realizing the rapid dispersion of reaction materials, effectively controlling the mixing of reaction raw materials, reducing the occurrence of excessive reaction or incomplete reaction and the like, preparing the solid granular modified alkylaluminoxane with low byproduct and low alkylaluminium content, wherein the yield of the modified alkylaluminoxane can generally reach more than 80 percent and can reach 98.4 percent to the maximum; the aluminum content in the modified alkylaluminoxane can generally reach 45 to 50 percent.

Although CN107722146A adopts a non-hydrolysis method, the alkylaluminoxane prepared by this method cannot participate in the subsequent reaction by using an inorganic carrier such as silica. In this method, since the raw materials such as aldehyde and ketone are brought into direct contact with the polyalkylaluminoxane, trialkylaluminum and hydrocarbon flux, all the raw materials are mixed, the degree of reaction cannot be controlled, the amount of side reaction products is large, the recovery rate of the polyaluminoxane composition as a solid product is not high, the amount of the solid aluminoxane composition deposited increases, and the increase in the amount of the deposited aluminoxane composition becomes slow when the amount reaches a certain level. No corresponding solution is provided for the above problems.

Furthermore, it is economically disadvantageous to be utilized commercially.

In the present invention, the term "m" and "n" means that the solution A and the solution B are respectively introduced into different channels, and the number of the channels is m and n, and then they are mixed together.

Preferably, the solution a containing aluminum alkyl is an aluminum alkyl solution or a solution of an aluminum alkyl precursor.

In the present invention, the aluminum alkyl precursor refers to the compounding of an aluminum alkyl with a solvent, for example, the compounding of an aluminum alkyl with toluene.

The solvent is generally toluene.

Preferably, the aluminum alkyl-containing solution a has a mass fraction of 1% to 70%, for example, 1%, 5%, 10%, 18%, 25%, 30%, 35%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 52%, 58%, 59%, 60%, 63%, 68%, 70%, or the like.

Preferably, the mass fraction of the aluminum alkyl is 40 to 60 percent.

Experiments show that the yield of the modified alkylaluminoxane prepared by the method is highest when the mass fraction of the alkylaluminium is controlled to be about 45%. Therefore, the mass fraction of the aluminum alkyl is most preferably controlled to be between 42% and 50%.

Preferably, the aluminum alkyl comprises one or a combination of at least two of trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, or tri-tert-butylaluminum.

Preferably, the mass fraction of the carbon-oxygen bond compound in the solution B containing the carbon-oxygen bond compound is 1% to 30%, and may be, for example, 1%, 5%, 8%, 13%, 14%, 16%, 20%, 24%, 28%, 29%, 30%, or the like.

Preferably, the mass fraction of the carbon-oxygen bond compound is 5 to 20 percent.

Preferably, the compound containing a carbon-oxygen bond comprises any one of benzophenone, benzoic acid, boric acid, silaborane, alkyl boric acid or boron-oxygen ester compounds or a combination of at least two of the benzophenone, the benzoic acid, the boric acid, the silaborane and the alkyl boric acid.

In the present invention, the alkyl boric acid includes methyl boric acid, ethyl boric acid, and the like; the boroxine compounds include trimethoxyboroxine, boric phenol esters, arylborates, and the like.

Preferably, the compound containing a carbon-oxygen bond is any one of benzophenone, benzoic acid, silaborane or trimethoxyboroxine or a combination of at least two of the benzophenone, the benzoic acid, the silaborane and the trimethoxyboroxine.

Preferably, m and n are both integers greater than 2, e.g., m may have a value of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc., and n may have a value of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

The values of m and n may or may not be equal.

Preferably, the cross-sectional area of each flow channel in m strands of the solution A is 0.1-10 mm²For example, it may be 0.1mm²、0.5mm²、1mm²、2mm²、3mm²、4mm²、5mm²、6mm²、7mm²、8mm²、9mm²Or 10mm²And the like.

Preferably, the cross-sectional area of each flow channel in the n of the solution B is 0.1-10 mm²For example, it may be 0.1mm²、0.5mm²、1mm²、2mm²、3mm²、4mm²、5mm²、6mm²、7mm²、8mm²、9mm²Or 10mm²And the like.

In the invention, the linear velocity of the material in the flow channel is influenced by the cross section area of the flow channel, and the linear velocity is too low, so that the material entering the reaction kettle cannot be rapidly dispersed, and the over-reaction is caused; too high a linear velocity can result in insufficient contact time of the different streams and incomplete reaction. Therefore, in the actual reaction process of the invention, the flow channel with the cross section area is preferably used, so that the reaction effect is optimal.

The mass ratio of the alkyl aluminum in the solution A to the compound having a carbon-oxygen bond in the solution B is preferably (0.1 to 2.0):1, and may be, for example, 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 1.9, 2.0, or the like.

Preferably, the mass ratio is (0.5-1.4): 1.

Preferably, the mass ratio is (0.8-1.2): 1.

In the present invention, the ratio is controlled to obtain different yields of alkylaluminoxane. Particularly, when the ratio is controlled to be between 0.8 and 1.2, the reaction effect is optimal, the byproducts are few, and the yield of the target product is highest.

Preferably, the temperature of the contact reaction is 30 to 100 ℃, for example, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃, preferably 50 to 80 ℃.

Preferably, the method of post-treatment comprises one or a combination of at least two of aging, filtration, vacuum drying or distillation.

Preferably, the method of reacting with silica comprises: mixing the alkylaluminoxane with the silicon dioxide and the solvent, stirring, filtering and drying to obtain the modified alkylaluminoxane.

Preferably, the solvent is toluene.

Preferably, the stirring method comprises the following steps: stirring for 0.5-1 h at normal temperature, then heating to 80-120 ℃ and continuing stirring for 0.5-1 h.

After stirring, generally cooling and standing for layering, filtering the material at the lower part, and drying in vacuum to obtain the modified alkylaluminoxane.

Preferably, the stirring is carried out under protection of a protective gas. The protective gas is typically nitrogen, argon-neon, or the like.

In a second aspect, the present invention provides a modified alkylaluminoxane prepared by the preparation method according to the first aspect.

In a third aspect, the present invention provides a cocatalyst for use in a polyolefin polymerization reaction, the cocatalyst comprising a modified alkylaluminoxane as described in the second aspect.

When the modified alkylaluminoxane provided by the invention is used as a cocatalyst, the modified alkylaluminoxane can be directly used for single-site catalysts such as a supported metallocene catalyst, a constrained geometry catalyst, a late transition metal catalyst, a non-metallocene catalyst and the like without using other carriers.

Compared with the prior art, the invention has the beneficial effects that:

the preparation method of the modified alkylaluminoxane provided by the invention uses a non-hydrolysis method, and makes the reaction condition milder and controllable through the reaction of the solution of alkylaluminium and the compound containing a carbon-oxygen bond, and simultaneously uses a shunting form to carry out the reaction, thereby realizing the rapid dispersion of reaction materials, effectively controlling the mixing of reaction raw materials, reducing the occurrence of the conditions of excessive reaction or incomplete reaction and the like, and being capable of preparing the solid granular modified alkylaluminoxane with low byproduct and low alkylaluminium content. The yield of the modified alkyl aluminoxane can generally reach more than 80 percent, and can reach 98.4 percent at most; the aluminum content in the modified alkylaluminoxane can generally reach 45 to 50 percent, and the effect is outstanding.

When the modified alkylaluminoxane provided by the invention is used as a cocatalyst, the modified alkylaluminoxane can be directly used for single-site catalysts such as a supported metallocene catalyst, a constrained geometry catalyst, a late transition metal catalyst, a non-metallocene catalyst and the like, and other carriers are not needed, so that the modified alkylaluminoxane is economical and practical, simple in reaction and high in application value.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions, the present invention is further described in detail below.