An alkoxytitanium non-metallocene catalyst for preparing polyethylene wax and its preparation method

Abstract

This invention relates to the field of catalyst synthesis technology, and more particularly to an alkoxytitanium non-metallocene catalyst for preparing polyethylene wax and its preparation method. The alkoxytitanium catalyst prepared by this invention can directly carry out ethylene polymerization. The polymerization process is simple, requires only a small amount of alkyl aluminum halides for impurity removal, and exhibits high catalytic activity. It requires no additional organoboron compounds or methylchlorooxyalkane, nor does it require chain transfer agents to adjust molecular weight. It has a novel structure, outstanding catalytic activity, and a simple synthesis process with diverse ligand designs. By designing different types of ligands, the molecular weight and activity of the polymer can be effectively improved, achieving precise control over catalyst activity and selectivity, thereby obtaining olefin polymers with specific structures and properties. This characteristic provides broad prospects for the preparation of polymer materials with specific properties and applications.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and in particular to an alkoxytitanium non-metallocene catalyst for preparing polyethylene wax and its preparation method. Background Technology

[0002] Polyethylene wax typically refers to low molecular weight polyolefins with a molecular weight of 1,000-10,000. It can be dissolved in aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and aliphatic hydrocarbon solvents. It has excellent chemical stability, a certain degree of corrosion resistance to chemicals such as acids and alkalis, and good compatibility with many polymers and materials. It is widely used in fields such as films, coatings, lubricants, ink additives, and plastic modifiers.

[0003] Currently, the production processes for polyethylene wax include ethylene cracking, ethylene polymerization by-product purification, and ethylene polymerization. Polyethylene wax produced by ethylene polymerization has advantages over the other two processes, including narrower molecular weight and melting range distribution, adjustable product performance, stable quality, and suitability for producing high-quality, diversified products; it is considered a high-end wax. International patents, such as ExxonMobil's US4914253, Hoechst AG's US5023388, and Clariant's US6080902 and US5750813, all involve polyethylene wax production using metallocene catalysts. These processes have limitations, such as higher costs, the need for chain transfer agents to adjust molecular weight, and less than ideal molecular weight control. While non-metallocene catalysts offer certain advantages, there is still room for improvement in activity and molecular weight control. Currently, my country's polyethylene wax industry mainly uses the first two processes, and high-end polyethylene wax products are heavily reliant on imports. In China, there are several patents related to the production of polyethylene wax via ethylene polymerization, including CN201280041261, CN107325207, CN111154017, and CN200480017722. These patents have promoted the development of polyethylene wax production to some extent, but several problems remain. For example, the molecular weight distribution of the produced metallocene polyethylene wax is relatively wide, lagging behind high-end foreign products; the activity of the metallocene catalyst needs improvement, limiting production efficiency; and the catalyst is relatively expensive, increasing production costs and hindering large-scale application.

[0004] Furthermore, current technologies for producing polyethylene wax all utilize metallocene catalysts, which have limitations such as high cost, the need to add chain transfer agents to adjust molecular weight, and less than ideal molecular weight control. While non-metallocene catalysts offer certain advantages, there is still room for improvement in terms of activity and molecular weight control.

[0005] In summary, there are currently some technical challenges in the domestic ethylene polymerization process for producing high-end polyethylene wax, mainly in the development and optimization of catalysts and the control of polymerization reaction conditions.

[0006] Therefore, developing a catalyst for high-end polyethylene wax and achieving good application results in the field of olefin polymerization is of great practical significance. Summary of the Invention

[0007] This invention discloses a highly stable and polymerizable alkoxytitanium catalyst and its preparation method. By precisely controlling the reaction conditions, a simple two-step synthesis process was successfully used to synthesize the alkoxytitanium non-metallocene catalyst. It exhibits a stable structure, good solubility, and demonstrates high catalytic activity and excellent high-temperature resistance in ethylene polymerization. The prepared polyethylene wax possesses ultra-low molecular weight, high crystallinity, and a narrow molecular weight distribution.

[0008] The first aspect of the present invention provides an alkoxytitanium non-metallocene catalyst for the preparation of polyethylene wax, said catalyst having any of the following structural formulas:

[0009]

[0010] A second aspect of the present invention provides a method for preparing an alkoxytitanium non-metallocene catalyst, comprising the following steps:

[0011] Under inert gas protection, titanium tetrachloride was added to an aliphatic hydrocarbon solvent, and then aliphatic alcohol was added dropwise to the aliphatic hydrocarbon solvent containing titanium tetrachloride through a dropping funnel. Triethylamine was then added. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, the aliphatic hydrocarbon solvent was removed by distillation, and the alkoxytitanium non-metallocene catalyst was obtained by vacuum distillation.

[0012] In some preferred embodiments, the preparation method further includes an optimization step, specifically comprising: reacting the alkoxytitanium non-metallocene catalyst with a compound having the structure shown in Formula I under an inert gas atmosphere, and finally removing the solvent by vacuum distillation to obtain the optimized alkoxytitanium non-metallocene catalyst, wherein R in Formula I... 1 R 2 R 3 Each of these is an independent functional group, selected from one or more of the following substituents: hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, isobutyl, tert-butyl, phenyl.

[0013]

[0014] In some preferred embodiments, the molar ratio of titanium tetrachloride to fatty alcohol is 1:(4-6).

[0015] In some preferred embodiments, the molar ratio of titanium tetrachloride to triethylamine is 1:(4-6).

[0016] In some preferred embodiments, the molar ratio of the alkoxytitanium non-metallocene catalyst to the compound having the structure shown in Formula I is 1:(4-6).

[0017] In some preferred embodiments, the fatty alcohol is selected from any one of isopropanol, cyclohexanol, or isooctyl alcohol.

[0018] In some preferred embodiments, the reaction temperature is -35°C to 110°C, and the reaction time is 30 min.

[0019] Preferably, the reaction temperature is 0-35℃ and the reaction time is 30 min.

[0020] In some preferred embodiments, the reaction temperature in the optimization step is -35℃ to 110℃, and the reaction time is 30 min.

[0021] Preferably, the reaction temperature in the optimization step is 50-80℃ and the reaction time is 30 min.

[0022] In some preferred embodiments, the inert gas includes at least one of nitrogen, helium, or argon.

[0023] This invention does not impose specific limitations on aliphatic hydrocarbon solvents, which can be selected from, but are not limited to, petroleum ethers.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The alkoxytitanium catalyst prepared by this invention is an orange-yellow complex with a stable structure. It can be stored for a long time at room temperature under an inert atmosphere and has good solubility in aromatic solvents.

[0026] (2) The alkoxy titanium catalyst prepared by the present invention can directly carry out ethylene polymerization reaction. The polymerization process system is simple, and the amount of alkyl aluminum halide used for impurity removal is high. The catalytic polymerization reaction activity is high. No additional organoboron compounds or methyl chlorooxyalkane need to be added, nor is it necessary to add chain transfer agents to adjust the molecular weight.

[0027] (3) The polyethylene wax product prepared using the alkoxy titanium catalyst of the present invention has the characteristics of ultra-low molecular weight, high crystallinity and narrow molecular weight distribution; and the molecular weight can be effectively adjusted in a variety of ways, such as adjusting the substituents on the phenyl or the polymerization reaction conditions. At the same time, the molecular weight distribution of the polyethylene wax produced by this process is narrower than that of polyethylene wax on the market; it has good high temperature resistance when catalyzing olefin polymerization reaction, and the polymerization reaction temperature can reach 140℃.

[0028] (4) The alkoxytitanium catalyst prepared by this invention has a simple preparation route, mild reaction conditions, and good reaction stability. It adopts a two-step synthesis technology, and only simple separation is required to obtain a high-purity catalyst. This process greatly reduces the required equipment and reagents, lowers production costs, has excellent reaction stability, high product yield, simple process, mild conditions, and low process cost, making it very suitable for large-scale industrial production.

[0029] (5) The alkoxy titanium catalyst prepared by this invention has a novel structure and outstanding catalytic activity. The synthesis process is simple and the ligand design is diverse. By designing different types of ligands, the molecular weight and activity of the polymer can be effectively improved, and the catalyst activity and selectivity can be precisely controlled, thereby obtaining olefin polymers with specific structures and properties. This characteristic provides a broad space for the preparation of polymer materials with specific properties and uses.

[0030] (6) When the alkoxytitanium catalyst prepared in this invention is used to catalyze olefin polymerization, its cost is significantly lower than that of expensive metallocene catalysts. Furthermore, it does not require the addition of methylaluminoxane or organoboron additives; only a small amount of purified Et3Al2Cl3 reagent is needed to exhibit high catalytic activity. In addition, this process does not require the addition of chain transfer agents such as hydrogen to adjust the molecular weight. The reaction temperature and ethylene pressure significantly affect the polymerization activity and the molecular weight of the resulting polyethylene. The produced polyethylene wax not only has higher activity but also achieves a wider range of molecular weights, making it more suitable for large-scale industrial production. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] All embodiments of the present invention were carried out in a glove box under an inert nitrogen atmosphere, with water and oxygen content in the glove box both less than 0.1 ppm, to ensure the stability of the experimental environment and avoid interference from water and oxygen on the reaction. Specific embodiments are as follows:

[0033] Example 1

[0034] This embodiment provides a method for synthesizing an alkoxy titanium catalyst, the steps of which include:

[0035] Under inert gas protection at room temperature, titanium tetrachloride (1.90 g, 10 mmol) was added to 50 mL of petroleum ether, and then fatty alcohol (isopropanol, 2.64 g, 44 mmol) was added dropwise to the petroleum ether containing titanium tetrachloride through a dropping funnel. Triethylamine (4.45 g, 44 mmol) was then added. After the reaction was completed, triethylamine hydrochloride was removed by filtration, petroleum ether was removed by distillation, and the alkoxytitanium non-metallocene catalyst Z1 was obtained by vacuum distillation.

[0036]

[0037] Example 2

[0038] This embodiment provides a method for synthesizing an alkoxy titanium catalyst, the steps of which include:

[0039] Under inert gas protection at room temperature, titanium tetrachloride (1.90 g, 10 mmol) was added to 50 mL of petroleum ether, and then a fatty alcohol (isooctanol, 5.73 g, 44 mmol) was added dropwise to the petroleum ether containing titanium tetrachloride through a dropping funnel. Triethylamine (4.45 g, 44 mmol) was then added. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, the petroleum ether was removed by distillation, and the alkoxytitanium non-metallocene catalyst Z2 was obtained by vacuum distillation.

[0040]

[0041] Example 3

[0042] This embodiment provides a method for synthesizing an alkoxy titanium catalyst, the steps of which include:

[0043] Under inert gas protection at room temperature, titanium tetrachloride (1.90 g, 10 mmol) was added to 50 mL of petroleum ether, and then a fatty alcohol (cyclohexanol, 4.40 g, 44 mmol) was added dropwise to the petroleum ether containing titanium tetrachloride through a dropping funnel. Triethylamine (4.45 g, 44 mmol) was then added. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, the petroleum ether was removed by distillation, and the alkoxytitanium non-metallocene catalyst Z3 was obtained by vacuum distillation.

[0044]

[0045] Example 4

[0046] This embodiment provides an alkoxytitanium catalyst (R 1 =R 2 =R 3 The optimization method for H) includes the following steps:

[0047] Under inert gas protection and at room temperature, compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and compound 4b (0.77 g, 8.2 mmol) was dissolved in 30 mL of toluene. The Z1 solution was slowly added to the 4b solution under nitrogen atmosphere, and the mixture was stirred at 60 °C for 3 h. Then, the mixture was stirred at room temperature for 24 h. The solvent was then removed, and the solid was washed with warm toluene to obtain the orange-yellow complex Z4.

[0048]

[0049] Example 5

[0050] This embodiment provides an alkoxytitanium catalyst (R 1 =R 2 =H,R 3 = t The optimization method for Bu includes the following steps:

[0051] Under inert gas protection and at room temperature, compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and compound 5b (1.23 g, 8.2 mmol) was dissolved in 30 mL of toluene. The Z1 solution was slowly added to the 5b solution under nitrogen atmosphere, and the mixture was stirred at 65 °C for 3 h. Then, the mixture was stirred at room temperature for 24 h. The solvent was then removed, and the solid was washed with warm toluene to obtain the orange-yellow complex Z5.

[0052]

[0053] Example 6

[0054] This embodiment provides an alkoxytitanium catalyst (R 1 =Me,R 2 =R 3 The optimization method for H) includes the following steps:

[0055] Under inert gas protection and at room temperature, compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and compound 6b (0.89 g, 8.2 mmol) was dissolved in 30 mL of toluene. Solution 1c was slowly added to solution 6b under nitrogen atmosphere, and the mixture was stirred at 65 °C for 3 h. Then, the mixture was stirred at room temperature for 24 h. The solvent was then removed, and the solid was washed with warm toluene to obtain the orange complex Z6.

[0056]

[0057] Example 7

[0058] This embodiment provides an alkoxytitanium catalyst (R 1 =t Bu, R 2 =R 3 The optimization method for H) includes the following steps:

[0059] Under inert gas protection and at room temperature, compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and compound 7b (1.23 g, 8.2 mmol) was dissolved in 30 mL of toluene. Solution 1c was slowly added to solution 7b under nitrogen atmosphere, and the mixture was stirred at 70 °C for 3 h. Then, the mixture was stirred at room temperature for 24 h. The solvent was then removed, and the solid was washed with warm toluene to obtain the yellow complex Z7.

[0060]

[0061] Example 8

[0062] This embodiment provides an alkoxytitanium catalyst (R 1 =Ph,R 2 =R 3 The optimization method for H) includes the following steps:

[0063] Under inert gas protection and at room temperature, compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and compound 8b (1.40 g, 8.2 mmol) was dissolved in 30 mL of toluene. The Z1 solution was slowly added to the 8b solution under nitrogen atmosphere, and the mixture was stirred at 65 °C for 3 h. Then, the mixture was stirred at room temperature for 24 h. The solvent was then removed, and the solid was washed with warm toluene to obtain the yellow complex Z8.

[0064]

[0065] Experimental Example

[0066] The catalyst prepared in the above examples is used to prepare polyethylene wax. The preparation method includes:

[0067] (1) The high-pressure intermittent reactor was evacuated repeatedly at 150°C and replaced with ethylene three times before ethylene was introduced. The pressure was adjusted to 0 MPa after exhaust.

[0068] (2) Under the conditions of 60℃ and 1MPa, ethylene was introduced into the high-pressure batch reactor, and 28.0mL of toluene dehydrated and deoxygenated by sodium metal reflux was added as a medium. 1mL of 0.6mol / L Et3Al2Cl3 / n-hexane solution was added. When the reactor temperature reached 100℃, 1mL of 2μmol / mL catalyst / toluene solution was quickly added. The reaction was carried out at a reactor pressure of 1MPa for 20min to carry out a high-temperature solution polymerization reaction.

[0069] (3) After the reaction is terminated, the mixture is cooled and the polymer solution is poured into acidified ethanol with a volume ratio of concentrated hydrochloric acid / ethanol of 1:9 to terminate the reaction. The mixture is then washed with ethanol and dried under vacuum to obtain the polyethylene wax.

[0070] Performance testing

[0071] Weight-average molecular weight, number-average molecular weight, and PDI (polymer dispersibility index) were tested using an Agilent PL-GPC220 high-temperature gel permeation chromatograph according to GB / T 27843-2011 standard: solvent 1,2,4-trichlorobenzene, test temperature 150℃, solvent flow rate 1 mL / min, sample mass concentration 1.0 g / L, and polystyrene as standard. The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] As shown in Table 1, the catalyst system of this invention, when preparing polyethylene wax, can adjust the molecular weight of polyethylene wax to a certain extent while maintaining a narrow molecular weight distribution by changing factors such as the type of fatty alcohol and the substituent of phenyl groups, thus meeting the specific molecular weight requirements of polyethylene wax in different application scenarios. Furthermore, the polyethylene waxes prepared in all examples exhibit ultra-low molecular weight characteristics, further demonstrating the advantages of this catalyst system in preparing polyethylene waxes with specific properties. This provides a good material basis for its application in films, coatings, lubricants, and other fields, helping to expand the application scope of polyethylene wax in related fields and improve product performance.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of an alkoxy titanium non-metallocene metal catalyst for the preparation of a polyethylene wax, characterized in that, The catalyst has any one of the following structural formulas: ； The catalyst is used to prepare a polyethylene wax, and a preparation method comprises the following steps: (1) A high-pressure batch reactor is repeatedly vacuumed and replaced by ethylene for three times at 150 DEG C in advance, and then ethylene is introduced, and the pressure is adjusted to 0 MPa by exhaust; (2) Under the conditions of 60 DEG C and 1 MPa, ethylene is introduced into the high-pressure batch reactor, 28.0 mL of toluene as a medium is continuously added, which is dehydrated and deoxidized by refluxing with sodium metal, 1 mL of an Et3Al2Cl3 / n-hexane solution with a concentration of 0.6 mol / L is added, when the temperature of the reactor reaches 100 DEG C, 1 mL of a catalyst / toluene solution with a concentration of 2 micromol / mL is rapidly added, and a high-temperature solution polymerization reaction is carried out under the condition that the pressure of the reactor is 1 MPa for 20 min; (3) After the reaction is terminated, the polymerization liquid is cooled and poured into acidified ethanol with a volume ratio of concentrated hydrochloric acid to ethanol being 1:9 to terminate the reaction, and the polyethylene wax is obtained by ethanol washing and vacuum drying.

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