Alkoxy titanium non-metallocene catalyst for preparing polyethylene wax and preparation method of alkoxy titanium non-metallocene catalyst

Abstract

The invention relates to the technical field of catalyst synthesis, in particular to an alkoxy titanium non-metallocene catalyst for preparing polyethylene wax and a preparation method of the alkoxy titanium non-metallocene catalyst. The alkoxy titanium catalyst prepared by the invention can be directly used for ethylene polymerization reaction, the polymerization process system is simple, and the alkyl aluminum halide with impurity removal dosage has high catalytic polymerization reaction activity; according to the present invention, no additional organic boron compound or methyl chlorooxane needs to be added, no chain transfer agent needs to be added to adjust the molecular weight, the structure is novel, the catalytic activity is outstanding, the synthesis process is simple, the ligand design is diversified, and the molecular weight and the activity of the polymer can be effectively improved by designing different types of ligands; accurate regulation and control on the activity and selectivity of the catalyst are achieved, then the olefin polymer with the specific structure and performance is obtained, and the characteristic provides a wide space for preparing high polymer materials with the specific performance and application.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst synthesis, and in particular to an alkoxy titanium non-metallocene catalyst for preparing polyethylene wax and a preparation method thereof. Background Art

[0002] Polyethylene wax usually refers to low molecular weight polyolefins with a molecular weight of 1000-10000. 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 acids, alkalis and other chemical substances, and has good compatibility with many polymers and materials. It is widely used in fields such as films, coatings, lubricants, ink additives and plastic modifiers.

[0003] At present, the production processes of polyethylene wax include ethylene cracking, ethylene polymerization byproduct purification, and ethylene polymerization. Among them, the polyethylene wax produced by the ethylene polymerization method has the advantages of narrow molecular weight and melting range distribution, adjustable product performance and stable quality, and is suitable for the production of high-quality diversified products compared with the first two processes, and is a high-end wax. International patents such as Exxon Chemical's patent US4914253, Germany's HoechstAG's patent US5023388, Clariant's patents US6080902 and US5750813, etc., these polyethylene wax production, are all metallocene catalyst production processes, which have some limitations, such as high cost, the need to add chain transfer agents to adjust the molecular weight, and the molecular weight control is not ideal. Although non-metallocene catalysts have certain advantages, there is still room for improvement in activity and molecular weight control. At present, my country's polyethylene wax industrial production mainly adopts the first two processes, and high-end polyethylene wax products are highly dependent on imports. The domestic patents for the production of polyethylene wax by ethylene polymerization include CN201280041261, CN107325207, CN111154017, CN200480017722, etc. These patents have promoted the production and development of polyethylene wax to a certain extent, but there are still some problems, such as the molecular weight distribution of the produced metallocene polyethylene wax is relatively wide, which is different from the high-end products abroad; the activity of metallocene catalyst needs to be improved, which limits the production efficiency; and the catalyst is relatively expensive, which increases the production cost and is not conducive to large-scale promotion and application.

[0004] In addition, the existing technology of polyethylene wax production uses metallocene catalysts, and the production process has some limitations, such as high cost, the need to add chain transfer agents to adjust the molecular weight, and the molecular weight control is not ideal. Although non-metallocene catalysts have certain advantages, there is still room for improvement in activity and molecular weight control.

[0005] In summary, there are some technical difficulties in the production of high-end polyethylene wax by domestic ethylene polymerization method, which are mainly reflected in the development and optimization of catalysts and the control of polymerization process reaction conditions.

[0006] In view of this, it is of great practical significance to develop a catalyst for high-end polyethylene wax and achieve good application effects in the field of olefin polymerization. Summary of the invention

[0007] The present invention discloses an alkoxy titanium catalyst with strong stability and excellent polymerization performance and a preparation method thereof. By precisely controlling the reaction conditions, the alkoxy titanium non-metallocene catalyst is successfully synthesized by a two-step simple synthesis preparation process. The catalyst has a stable structure and good solubility, and exhibits high catalytic activity and excellent high temperature resistance in ethylene polymerization. The prepared polyethylene wax has the characteristics of ultra-low molecular weight, high crystallinity and narrow molecular weight distribution.

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

[0009]

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

[0011] Under the protection of inert gas, titanium tetrachloride is added to an aliphatic hydrocarbon solvent, and then aliphatic alcohol is dripped into the aliphatic hydrocarbon solvent containing titanium tetrachloride through a dropping funnel, and triethylamine is added; after the reaction is completed, triethylamine hydrochloride is removed by filtration, the aliphatic hydrocarbon solvent is removed by distillation, and the alkoxy titanium non-metallocene catalyst is obtained by reduced pressure distillation.

[0012] In some preferred embodiments, the preparation method further comprises an optimization step, specifically comprising: reacting an alkoxy titanium non-metallocene catalyst with a compound having a structure shown in Formula I under the protection of an inert gas, and finally removing the solvent by distillation under reduced pressure to obtain an optimized alkoxy titanium non-metallocene catalyst, wherein R in Formula I 1 , R 2 , R 3 are independent groups selected from one or more of the following substituent groups: 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°C and the reaction time is 30 min.

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

[0021] Preferably, the reaction temperature in the optimization step is 50-80° C. 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] The present invention does not impose any particular limitation on the aliphatic hydrocarbon solvent, and the aliphatic hydrocarbon solvent may be selected from but is not limited to petroleum ether.

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

[0025] (1) The alkoxy titanium catalyst prepared by the present invention is an orange-yellow complex with a stable structure, can be stored for a long time under an inert atmosphere at room temperature, and has good solubility in aromatic hydrocarbon solvents;

[0026] (2) The alkoxytitanium catalyst prepared by the present invention can directly carry out ethylene polymerization reaction, the polymerization process system is simple, the alkyl aluminum halide used for impurity removal has high catalytic polymerization activity; there is no need to add additional organic boron compounds or methyl chloroform, and there is no need 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 group 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°C;

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

[0029] (5) The alkoxytitanium catalyst prepared by the present invention has a novel structure, outstanding catalytic activity, simple synthesis process, and diversified ligand design. 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 feature provides a broad space for the preparation of polymer materials with specific properties and uses.

[0030] (6) When the alkoxytitanium catalyst prepared by the present invention is used to catalyze olefin polymerization, the cost is significantly reduced compared to expensive metallocene catalysts, and no additional methylaluminoxane or organic boron additive is required. Only a small amount of Et3Al2Cl3 reagent that has been treated with impurities is required to show high catalytic activity. In addition, the process does not require the addition of chain transfer agents such as hydrogen to adjust the molecular weight. The reaction temperature and ethylene pressure have a significant effect on the polymerization activity and the molecular weight of the resulting polyethylene. The polyethylene wax produced is not only more active, but also can achieve a higher range of molecular weight, which makes it have a wider application value and is very suitable for large-scale industrial production. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The embodiments of the present invention are all carried out in a glove box with an inert nitrogen atmosphere, and the water and oxygen contents in the glove box are less than 0.1 ppm to ensure the stability of the experimental environment and avoid interference of water and oxygen on the reaction. The specific embodiments are as follows:

[0033] Example 1

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

[0035] Under the protection of inert gas, at room temperature, titanium tetrachloride (1.90 g, 10 mmol) was added to 50 mL of petroleum ether, and then a fatty alcohol (isopropanol, 2.64 g, 44 mmol) was dropped into the petroleum ether containing titanium tetrachloride through a dropping funnel, and triethylamine (4.45 g, 44 mmol) was added; after the reaction was completed, triethylamine hydrochloride was filtered out, petroleum ether was distilled off, and alkoxy titanium non-metallocene catalyst Z1 was obtained by reduced pressure distillation;

[0036]

[0037] Example 2

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

[0039] Under the protection of inert gas, 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 dropped into the petroleum ether containing titanium tetrachloride through a dropping funnel, and triethylamine (4.45 g, 44 mmol) was added; after the reaction was completed, triethylamine hydrochloride was filtered out, petroleum ether was distilled off, and alkoxy titanium non-metallocene catalyst Z2 was obtained by reduced pressure distillation;

[0040]

[0041] Example 3

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

[0043] Under the protection of inert gas, 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 dropped into the petroleum ether containing titanium tetrachloride through a dropping funnel, and triethylamine (4.45 g, 44 mmol) was added; after the reaction was completed, triethylamine hydrochloride was filtered out, petroleum ether was distilled off, and alkoxy titanium non-metallocene catalyst Z3 was obtained by reduced pressure distillation;

[0044]

[0045] Example 4

[0046] This embodiment provides an alkoxy titanium catalyst (R 1 =R 2 =R 3 =H) optimization method, the steps comprising:

[0047] Under the protection of inert gas, at room temperature, the compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and the 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 stirred at 60°C for 3 h. Then stirred at room temperature for 24 h. Then the solvent was removed, and the solid was washed with warm toluene to obtain an orange-yellow compound Z4.

[0048]

[0049] Example 5

[0050] This embodiment provides an alkoxy titanium catalyst (R 1 =R 2 =H, R 3 = t Bu) optimization method, the steps comprising:

[0051] Under the protection of inert gas, at room temperature, the compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and the 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 stirred at 65°C for 3 h. Then stirred at room temperature for 24 h. Then the solvent was removed, and the solid was washed with warm toluene to obtain an orange-yellow compound Z5.

[0052]

[0053] Example 6

[0054] This embodiment provides an alkoxy titanium catalyst (R 1 =Me, R 2 =R 3 =H) optimization method, the steps comprising:

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

[0056]

[0057] Example 7

[0058] This embodiment provides an alkoxy titanium catalyst (R 1 =t Bu, R 2 =R 3 =H) optimization method, the steps comprising:

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

[0060]

[0061] Example 8

[0062] This embodiment provides an alkoxy titanium catalyst (R 1 =Ph, R 2 =R 3 =H) optimization method, the steps comprising:

[0063] Under the protection of inert gas, at room temperature, the compound Z1 (0.57 g, 2 mmol) prepared in Example 1 was dissolved in 25 mL of toluene, and the 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 stirred at 65°C for 3 h. Then stirred at room temperature for 24 h. Then the solvent was removed, and the solid was washed with warm toluene to obtain a yellow compound Z8.

[0064]

[0065] Experimental example

[0066] The catalyst prepared in the above embodiment is used to prepare polyethylene wax, and the preparation method comprises:

[0067] (1) The high-pressure batch reactor was repeatedly evacuated and replaced with ethylene at 150°C for 3 times in advance, and then ethylene was introduced and the exhaust pressure was adjusted to 0 MPa;

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

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

[0070] Performance Testing

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

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, when preparing polyethylene wax, the catalyst system of the present invention can adjust the molecular weight of polyethylene wax to a certain extent by changing factors such as the type of fatty alcohol and phenyl substituents while maintaining a relatively narrow molecular weight distribution, so as to meet the specific requirements of different application scenarios for the molecular weight of polyethylene wax. At the same time, the polyethylene waxes prepared in all embodiments have the characteristics of ultra-low molecular weight, which further proves the advantages of the catalyst system in preparing polyethylene wax with specific properties, provides a good material basis for its application in the fields of films, coatings, lubricants, etc., and helps to expand the application scope of polyethylene wax in related fields and improve product performance.

[0076] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An alkoxytitanium non-metallocene catalyst for preparing polyethylene wax, characterized in that: The catalyst has any of the following structural formulas:

2. A method for preparing an alkoxytitanium non-metallocene catalyst according to claim 1, characterized in that: include: Under the protection of inert gas, titanium tetrachloride is added to an aliphatic hydrocarbon solvent, and then aliphatic alcohol is dripped into the aliphatic hydrocarbon solvent containing titanium tetrachloride through a dropping funnel, and triethylamine is added; after the reaction is completed, triethylamine hydrochloride is removed by filtration, the aliphatic hydrocarbon solvent is removed by distillation, and the alkoxy titanium non-metallocene catalyst is obtained by reduced pressure distillation.

3. The preparation method according to claim 2, characterized in that: The preparation method further comprises an optimization step, specifically comprising: reacting the alkoxy titanium non-metallocene catalyst with a compound having a structure shown in Formula I under the protection of an inert gas, and finally removing the solvent by distillation under reduced pressure to obtain an optimized alkoxy titanium non-metallocene catalyst, wherein R in Formula I 1 , R 2 , R 3 are independent groups selected from one or more of the following substituent groups: hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, isobutyl, tert-butyl, phenyl, 4. The preparation method according to claim 2, characterized in that: The molar ratio of titanium tetrachloride to fatty alcohol is 1:(4-6).

5. The preparation method according to claim 2, characterized in that: The molar ratio of titanium tetrachloride to triethylamine is 1:(4-6).

6. The preparation method according to claim 3, characterized in that: The molar ratio of the alkoxytitanium non-metallocene catalyst to the compound having the structure shown in formula I is 1:(4-6).

7. The preparation method according to claim 2, characterized in that: The fatty alcohol is selected from any one of isopropanol, cyclohexanol or isooctyl alcohol.

8. The preparation method according to claim 2, characterized in that: The reaction temperature is -35°C to 110°C, and the reaction time is 30 minutes.

9. The preparation method according to claim 3, characterized in that: The reaction temperature in the optimization step is -35°C to 110°C, and the reaction time is 30 minutes.

10. The preparation method according to claim 3, characterized in that: The inert gas includes at least one of nitrogen, helium or argon.

Images