Composite catalyst and use thereof

Abstract

The present invention relates to the field of polymer synthesis. Specifically disclosed are a composite catalyst and a use thereof. In the present invention, RTiX3 is used as a primary catalyst for styrene polymerization, and exhibits high catalytic polymerization activity at a high temperature with the assistance of a co-catalyst, and a resulting polymer product can be dissolved in a reaction solvent at a high temperature without precipitation, thereby always maintaining a uniformly homogeneous liquid phase state. The heat transfer and mass transfer can occur readily, and the conversion rate and single-reactor efficiency can be greatly improved, thereby achieving the purposes of improving production efficiency and reducing production costs.

Description

A composite catalyst and its application

[0001] This application claims priority to Chinese Patent Application No. 202510202550.X, filed on February 24, 2025, entitled “A Composite Catalyst and Its Application”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of polymer synthesis, specifically relating to a composite catalyst and its application. Background Technology

[0003] Syndiotactic polystyrene (SPS) is a type of polystyrene that possesses the good chemical inertness, excellent electrical insulation, and moisture resistance of general-purpose polystyrene. Unlike general-purpose polystyrene, SPS has a syndiotactic stereostructure, with side groups (benzene rings) alternating on both sides of the macromolecular chain in its structural units. Due to its high stereoregularity, SPS has a strong crystallization ability, making it a crystallizable polymer with a high melting point of approximately 270°C. This highly crystalline aggregated structure endows SPS with good heat resistance and corrosion resistance, making its performance comparable to thermoplastic engineering plastics such as nylon, polyester, and polyphenylene sulfide, thus making it a cost-effective engineering plastic.

[0004] The greatest challenge in the synthesis of syndiotactic polystyrene lies in its heterogeneous nature. Typically, the optimal activity temperature of catalysts for syndiotactic polystyrene synthesis is below 100°C, such as commonly used cyclopentadienyl or alkyl-substituted cyclopentadienyl metallocene catalysts, whose optimal activity temperature is 50-90°C, decreasing at higher temperatures. However, due to the rapid crystallization and high solvent resistance of syndiotactic polystyrene, once the polymer is formed at polymerization temperatures of 50-90°C, it will inevitably precipitate from the liquid phase. During this process, the syndiotactic polystyrene precipitate readily absorbs monomers to form swollen bodies, adhering to the inner wall of the reactor and the agitator. If there are dead zones in the agitation, or if the breaking and dispersion are not timely and sufficient, the swollen bodies will gradually accumulate, agglomerate, and harden into waste material, which is not only difficult to shear and break up but also requires a significant increase in agitation power. Therefore, the heterogeneous nature greatly affects heat and mass transfer during the polymerization process, making stirring extremely difficult and heat removal very challenging. This also results in very low heat transfer efficiency in the later stages of polymerization, making polymerization difficult to proceed. Therefore, the current main production process for syndiotactic polystyrene is solution polymerization. Solution polymerization requires the addition of a solvent of equivalent mass to the styrene monomer for dilution, which effectively solves the swelling and agglomeration problem during the production of syndiotactic polystyrene. However, even when the solution content reaches 80%, the system will become a very viscous heterogeneous state once the solid content reaches 10%, making stirring and heat transfer more difficult in the later stages of polymerization. The styrene conversion rate is unlikely to exceed 80%, resulting in a very low single-reactor yield for syndiotactic polystyrene production via solution polymerization (single-reactor yield = monomer concentration × monomer conversion rate). This is detrimental to cost control and efficiency improvement for enterprises. Furthermore, solution polymerization involves the distillation separation and recovery of solvent and unreacted styrene, making the process complex and requiring highly sophisticated reaction equipment to improve heat and mass transfer, which also leads to significant production investment.

[0005] Therefore, it is necessary to solve the problem of heterogeneous polymerization under low solvent content, especially to improve the heat and mass transfer efficiency of styrene solid content systems in order to achieve high production efficiency. Summary of the Invention

[0006] In view of the problems of swelling, low conversion rate and low production efficiency caused by heterogeneous polymerization in the synthesis of syndiotactic polystyrene mentioned above, the present invention will provide a composite catalyst and its application.

[0007] To achieve the above objectives, the following technical solutions are specifically included:

[0008] A composite catalyst comprising a main catalyst and a co-catalyst, wherein the main catalyst has the chemical formula RTiX3, wherein R is inden(1,2,3-cd)pyrene or an inden(1,2,3-cd)pyrene containing substituents; and X is independently selected from halogen atoms, C 1-8Alkyl, C 2-8 alkenyl, C 3-8 Alkenyl, C 1-8 Alkoxy, aryl, C 7-10 Aryl alkyl, C 7-10 The catalyst is any one of alkylaryl groups; the cocatalyst includes a first cocatalyst and a second cocatalyst; the first cocatalyst includes an alkylaluminum catalyst; the second cocatalyst includes at least one of a borate catalyst and a phenyl catalyst.

[0009] In some embodiments, the halogen atom is F, Cl, or Br.

[0010] In some implementations, the C 1-8 The alkyl group is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl.

[0011] In some implementations, the C 2-8 Alkenyl groups include vinyl, propenyl, or butenyl.

[0012] In some implementations, the C 3-8 Alkenyl groups include allyl, allyl, or allyl.

[0013] In some implementations, the C 1-8 Alkoxy groups include methoxy, ethoxy, or propoxy.

[0014] In some embodiments, the aryl group includes a phenyl group.

[0015] In some implementations, the C 7-10 Aryl groups include benzyl, phenethyl, or phenylpropyl.

[0016] In some implementations, the C 7-10 Alkyl groups include 4-methyl-phenyl, 4-ethyl-phenyl, or 4-propyl-phenyl.

[0017] In some embodiments, the substituents in the substituent-containing inden(1,2,3-cd)pyrene group include C 1-8 alkyl, C 1-8 One of the alkoxy groups.

[0018] In some embodiments, the main catalyst comprises at least one of the following compounds:

[0019] In some embodiments, the preparation method of the main catalyst includes the following steps:

[0020] (1) Add indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene-containing compounds with substituents to potassium bis(trimethylsilyl)amide in a solvent and react at 50-70°C for 7-9 hours; then add trimethylchlorosilane and react at room temperature for 1-3 hours; then add titanium tetrachloride and react at room temperature for 1-3 hours to obtain an intermediate product;

[0021] (2) The intermediate product, solvent and X-ONa are mixed and reacted at 70-90°C for 5-7 hours to obtain the main catalyst; the X in X-ONa is the same as the X in the chemical formula RTiX3 of the main catalyst.

[0022] In some implementations, the room temperature in step (1) is 20-30°C.

[0023] In some embodiments, in step (1), the molar ratio of indene(1,2,3-cd)pyrene or a substituent-containing indene(1,2,3-cd)pyrene compound, bis(trimethylsilyl)amide potassium, trimethylchlorosilane, and titanium tetrachloride is indene(1,2,3-cd)pyrene or a substituent-containing indene(1,2,3-cd)pyrene compound: bis(trimethylsilyl)amide potassium: trimethylchlorosilane: titanium tetrachloride = 1:(0.9-1.2):(0.9-1.2):(0.9-1.2).

[0024] In some embodiments, in step (1), the solvent comprises tetrahydrofuran.

[0025] In some embodiments, in step (1), the amount of indo(1,2,3-cd)pyrene or the indo(1,2,3-cd)pyrene compound containing a substituent is 2-10 mL of solvent containing 1 mmol of indo(1,2,3-cd)pyrene or the indo(1,2,3-cd)pyrene compound containing a substituent.

[0026] In some embodiments, in steps (1)-(2), the molar ratio of the indo(1,2,3-cd)pyrene or the indo(1,2,3-cd)pyrene compound containing substituents to the X-ONa is 1:(0.9-1.2).

[0027] In some embodiments, in step (2), the solvent includes toluene.

[0028] In some embodiments, in step (1), the amount of X-ONa used is 2-10 mL of solvent containing 1 mmol of X-ONa.

[0029] In some embodiments, the molar ratio of the main catalyst to the co-catalyst is 1:(1 to 150).

[0030] In some embodiments, the molar ratio of the first cocatalyst to the second cocatalyst is (1-50):1.

[0031] In some embodiments, the alkylaluminum catalyst is selected from at least one of triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, methylaluminoxane, and modified methylaluminoxane.

[0032] In some embodiments, the borate catalyst is selected from at least one of triphenylmethyl-tetra(pentafluorophenyl)borate, N,N-dimethylaniline-tetra(pentafluorophenyl)borate, and N,N-dimethylaniline-tetraphenylborate.

[0033] In some embodiments, the phenyl catalyst includes at least one of diphenylzinc and phenylsilane.

[0034] This invention also provides the application of the aforementioned composite catalyst in the preparation of syndiotactic polystyrene.

[0035] This invention also provides a method for preparing syndiotactic polystyrene, comprising the following steps:

[0036] Styrene, solvent, and the composite catalyst according to any one of claims 1 to 9 are added to a reactor to carry out a polymerization reaction to obtain the syndiotactic polystyrene; the polymerization reaction temperature is 130 to 170°C, and the solvent is a halobenzene or halohydrocarbon with a boiling point greater than 130°C.

[0037] In some embodiments, the amount of the main catalyst is 0.004 to 0.03 mmol / 1 mol styrene.

[0038] In some embodiments, the solvent is selected from at least one of o-dichlorobenzene, trichlorobenzene, and tetrachloroethane.

[0039] In some embodiments, the mass ratio of styrene to solvent is 1:(0.1-0.5).

[0040] In some embodiments, the number-average molecular weight of the syndiotactic polystyrene is 2 × 10⁻⁶. 5 ~3×10 5 g / mol.

[0041] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses RTiX3 as the main catalyst for styrene polymerization. With the assistance of a co-catalyst, it can exert high catalytic polymerization activity at high temperature. The polymer products produced can dissolve in the reaction solvent at high temperature without precipitation, thus maintaining a uniform liquid phase state. Heat and mass transfer is relatively easy, which can significantly improve the styrene conversion rate and single-reactor efficiency, thereby achieving the purpose of improving production efficiency and reducing production costs. Detailed Implementation

[0042] This invention provides a composite catalyst comprising a main catalyst and a co-catalyst. The main catalyst has the chemical formula RTiX3, wherein R is inden(1,2,3-cd)pyrene or an inden(1,2,3-cd)pyrene containing substituents; and X is selected from halogen atoms, C... 1-8 Alkyl, C 2-8 alkenyl, C 3-8 Alkenyl, C 1-8 Alkoxy, aryl, C 7-10 Aryl alkyl, C 7-10 The catalyst is any one of alkylaryl groups; the cocatalyst includes a first cocatalyst and a second cocatalyst; the first cocatalyst includes an alkylaluminum catalyst; the second cocatalyst includes at least one of a borate catalyst and a phenyl catalyst.

[0043] Compared with existing catalysts, this invention uses RTiX3 as the main catalyst for styrene polymerization. With the assistance of a co-catalyst, it can exhibit high catalytic polymerization activity at high temperatures of 130–170°C. Furthermore, the syndiotactic polystyrene product produced in the reaction can dissolve in the reaction solvent at high temperatures, and the syndiotactic polystyrene product will not precipitate. As a result, the polymerization reaction system always maintains a homogeneous liquid phase, making heat and mass transfer easier. This can significantly improve the conversion rate of styrene and the efficiency of a single reactor, thereby achieving the goal of improving production efficiency and reducing production costs.

[0044] Specifically, the halogen atom is F, Cl, or Br; the C 1-8 The alkyl group is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl; the C 2-8 Alkenyl groups include, but are not limited to, vinyl, propenyl, or butenyl groups; the C 3-8 Alkenyl groups include, but are not limited to, allyl, allyl, or allenyl; the C 1-8 Alkoxy groups include, but are not limited to, methoxy, ethoxy, or propoxy groups; the aryl group includes, but is not limited to, phenyl groups; the C group... 7-10 Aryl groups include, but are not limited to, benzyl, phenethyl, or phenylpropyl; the C 7-10 Alkyl groups include, but are not limited to, 4-methyl-phenyl, 4-ethyl-phenyl, or 4-propyl-phenyl.

[0045] Preferably, the substituents in the indo(1,2,3-cd)pyrene group containing substituents include C 1-8 alkyl, C 1-8 One of the alkoxy groups.

[0046] It should be understood that the "C" appearing in this invention 1-8 "C" refers to any integer between 1 and 8 carbon atoms;2-8 "C" refers to any integer between 2 and 8 carbon atoms; 3-8 "C" refers to any integer between 3 and 8 carbon atoms; 1-9 "" refers to any integer between 1 and 9 carbon atoms.

[0047] Preferably, the main catalyst comprises at least one of the following compounds:

[0048] Preferably, the preparation method of the main catalyst includes the following steps:

[0049] (1) Add indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene-containing compounds with substituents to potassium bis(trimethylsilyl)amide in a solvent and react at 50-70°C for 7-9 hours; then add trimethylchlorosilane and react at room temperature for 1-3 hours; then add titanium tetrachloride and react at room temperature for 1-3 hours to obtain an intermediate product;

[0050] (2) The intermediate product, solvent and X-ONa are mixed and reacted at 70-90°C for 5-7 hours to obtain the main catalyst; the X in X-ONa is the same as the X in the chemical formula RTiX3 of the main catalyst.

[0051] More preferably, in step (1), the room temperature is 20-30°C.

[0052] More preferably, in step (1), the molar ratio of indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene compound containing substituents, bis(trimethylsilyl)amide potassium, trimethylchlorosilane and titanium tetrachloride is indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene compound containing substituents: bis(trimethylsilyl)amide potassium: trimethylchlorosilane: titanium tetrachloride = 1:(0.9-1.2):(0.9-1.2):(0.9-1.2).

[0053] More preferably, in step (1), the solvent includes tetrahydrofuran.

[0054] More preferably, in step (1), the amount of indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene containing substituents used is 2-10 mL of solvent containing 1 mmol of indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene containing substituents.

[0055] More preferably, in steps (1)-(2), the molar ratio of the indeno(1,2,3-cd)pyrene or the indeno(1,2,3-cd)pyrene compound containing substituents to the X-ONa is 1:(0.9-1.2).

[0056] More preferably, in step (2), the solvent includes toluene.

[0057] More preferably, in step (1), the amount of X-ONa used is 1 mmol of X-ONa in 2-10 mL of solvent.

[0058] Preferably, the molar ratio of the main catalyst to the co-catalyst is 1:(1 to 150), specifically 1:1, 1:25, 1:50, 1:75, 1:100, 1:125, 1:150, etc., as well as any value between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the values ​​included in the range.

[0059] The main catalyst and the co-catalyst work together to catalyze the polymerization of styrene with higher activity. Since the catalytic activity of the co-catalyst is lower than that of the main catalyst, the catalytic activity is better when the amount of co-catalyst added is greater than that of the main catalyst.

[0060] Preferably, the co-catalyst comprises a first co-catalyst and a second co-catalyst; the first co-catalyst comprises an alkylaluminum catalyst; and the second co-catalyst comprises at least one of a borate catalyst and a phenyl catalyst.

[0061] The inventors of this invention have discovered that when the above two types of catalysts are selected as co-catalysts, they can better complement the main catalyst to improve the catalytic activity of the composite catalyst.

[0062] Preferably, the molar ratio of the first cocatalyst and the second cocatalyst is (1-50):1, specifically 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, etc., as well as any value between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the values ​​included in the range.

[0063] Preferably, the alkylaluminum catalyst is selected from at least one of triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, methylaluminoxane, and modified methylaluminoxane.

[0064] Preferably, the borate catalyst is selected from at least one of triphenylmethyl-tetra(pentafluorophenyl)borate, N,N-dimethylaniline-tetra(pentafluorophenyl)borate, and N,N-dimethylaniline-tetraphenylborate.

[0065] Preferably, the phenyl catalyst includes at least one of diphenylzinc and phenylsilane.

[0066] The present invention also provides an application of the aforementioned composite catalyst in the preparation of syndiotactic polystyrene.

[0067] Furthermore, the present invention also provides a method for preparing syndiotactic polystyrene, comprising the following steps:

[0068] Styrene, solvent, and the aforementioned composite catalyst are added to a reactor to carry out a polymerization reaction to obtain the syndiotactic polystyrene; the solvent is a halobenzene or halohydrocarbon with a boiling point greater than 130°C.

[0069] Preferably, the temperature of the polymerization reaction can be 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, etc., or any value between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the points included in the range.

[0070] In the method for preparing syndiotactic polystyrene of the present invention, due to the special cyclopentadienylene chemical structure of the main catalyst RTiX3, it can exist stably at 130-170℃. Therefore, during the polymerization reaction, the composite catalyst can maintain high activity at 130-170℃, and the polymer formed by styrene polymerization at this temperature can be dissolved in a small amount of non-toluene solvent. This makes the entire polymerization reaction maintain a homogeneous liquid phase, and the stirring and heat transfer requirements can be met by using a conventional reactor (such as a single-shaft anchor-type stirred paddle reactor). This overcomes the defects of easy swelling and low mass and heat transfer efficiency caused by heterogeneity in conventional processes, and obtains a styrene conversion rate of more than 90%, which significantly improves production efficiency and has broad prospects for industrial application.

[0071] Preferably, the amount of the main catalyst is 0.004 to 0.03 mmol / 1 mol styrene.

[0072] Preferably, the solvent is selected from at least one of o-dichlorobenzene, trichlorobenzene, and tetrachloroethane.

[0073] Preferably, the mass ratio of styrene to solvent is 1:(0.1-0.5), specifically 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, etc., as well as any value between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the points included in the range.

[0074] In the polymerization reaction system of the present invention, the polymer formed by the polymerization of styrene can be dissolved in a small amount of non-toluene solvent, thereby keeping the entire polymerization reaction in a homogeneous liquid phase. Therefore, the amount of solvent required for the reaction system can be less than the amount of styrene raw material, which improves the yield per batch. Moreover, the amount of solvent in the reaction product is small, so there is no need for further distillation separation and recovery, which simplifies the process flow, improves production efficiency and reduces production costs.

[0075] Preferably, the syndiotactic polystyrene has a number-average molecular weight of 2 × 10⁻⁶. 5 ~3×10 5 g / mol.

[0076] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0077] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0078] Indo(1,2,3-cd)pyrenetrimethyltitanium (denoted as A1#): Prepared in-house, the process is as follows:

[0079] In a glove box, 1 mmol of indeno(1,2,3-cd)pyrene and 1 mmol of bis(trimethylsilyl)amide potassium were added to 5 mL of tetrahydrofuran and stirred at 60 °C for 8 h. Then, 1 mmol of trimethylchlorosilane was added and stirred at room temperature for 2 h. Next, 1 mmol of titanium tetrachloride was added and stirred at room temperature for 2 h, resulting in a brown solid-liquid mixture. After filtering to remove the filtrate, the mixture was washed three times with tetrahydrofuran (5 mL each time), and the solvent was removed under reduced pressure to obtain an intermediate product. 5 mL of toluene and 1 mmol of sodium methoxide were added to the intermediate product, and the mixture was reacted at 80 °C for 6 h. The solvent was then removed under reduced pressure, and the resulting yellow solid was washed three times with n-hexane (5 mL each time) and then removed under reduced pressure to obtain a yellow powder, which was indeno(1,2,3-cd)pyrene trimethyl titanium.

[0080] The NMR characterization results of indonop-(1,2,3-cd)pyrenetrimethyltitanium were as follows: δ = 7.78, 2H; δ = 7.72, 2H; δ = 7.64, 1H; δ = 7.55, 1H; δ = 7.55, 1H; δ = 7.51, 1H; δ = 7.43, 1H; δ = 7.40, 1H; δ = 7.35, 1H; δ = 7.31, 1H; δ = 1.20, 9H; where the deuterated solvent was deuterated acetone. The target molecular formula for elemental analysis is C1. 25 H 24Ti (%) = C: 80.61%, H: 6.45%. This indicates the successful synthesis of indono(1,2,3-cd)pyrene trimethyltitanium, whose chemical structure is as follows:

[0081] Indo(1,2,3-cd)pyrene-triallyltitanium (denoted as A2#): Self-made, the process is as follows:

[0082] In a glove box, 1 mmol of indeno(1,2,3-cd)pyrene and 1 mmol of bis(trimethylsilyl)amide potassium were added to 5 mL of tetrahydrofuran and stirred at 60 °C for 8 h. Then, 1 mmol of trimethylchlorosilane was added and stirred at room temperature for 2 h. Next, 1 mmol of titanium tetrachloride was added and stirred at room temperature for 2 h, resulting in a brown solid-liquid mixture. After the solvent was removed, the mixture was washed three times with tetrahydrofuran (5 mL each time), and the solvent was removed under reduced pressure to obtain an intermediate product. 5 mL of toluene and 1 mmol of sodium allyl oxide were added to the intermediate product, and the mixture was reacted at 80 °C for 6 h. The solvent was then removed, and the resulting yellow solid was washed three times with n-hexane (5 mL each time) and then removed under reduced pressure to obtain a yellow powder, which is indeno(1,2,3-cd)pyrene-triallyl titanium.

[0083] The NMR characterization results of indenop-(1,2,3-cd)pyrene-tracenepropyl titanium were as follows: δ = 7.78, 2H; δ = 7.72, 2H; δ = 7.64, 1H; δ = 7.55, 1H; δ = 7.55, 1H; δ = 7.51, 1H; δ = 7.43, 1H; δ = 7.40, 1H; δ = 7.35, 1H; δ = 7.31, 1H; δ = 5.99, 3H; δ = 5.29, 3H; δ = 5.16, 3H; δ = 1.75, 6H; The deuterated solvent was deuterated acetone. The target molecular formula for elemental analysis is C1. 31 H 27 Ti (%) = C: 83.32%, H: 6.08%. This indicates the successful synthesis of indenop-(1,2,3-cd)pyrene-tracenepropyl titanium, whose chemical structure is as follows:

[0084] Indo(1,2,3-cd)pyrene tribenzyl titanium (denoted as A3#): self-made, the process is as follows:

[0085] In a glove box, 1 mmol of indeno(1,2,3-cd)pyrene and 1 mmol of bis(trimethylsilyl)amide potassium were added to 5 mL of tetrahydrofuran and stirred at 60 °C for 8 h. Then, 1 mmol of trimethylchlorosilane was added and stirred at room temperature for 2 h. Next, 1 mmol of titanium tetrachloride was added and stirred at room temperature for 2 h, resulting in a brown solid-liquid mixture. After filtering to remove the filtrate, the mixture was washed three times with tetrahydrofuran (5 mL each time), and the solvent was removed under reduced pressure to obtain an intermediate product. 5 mL of toluene and 1 mmol of sodium benzyloxide were added to the intermediate product, and the mixture was reacted at 80 °C for 6 h. The solvent was then removed under reduced pressure, and the resulting yellow solid was washed three times with n-hexane (5 mL each time) and then removed under reduced pressure to obtain a yellow powder, which is indeno(1,2,3-cd)pyrene-tribenzyl titanium.

[0086] The NMR characterization results of indonop-(1,2,3-cd)pyrene tribenzyl titanium were as follows: δ = 7.70, 2H; δ = 7.51, 2H; δ = 7.39, 2H; δ = 3.45, 2H; δ = 7.20, 15H; δ = 2.40, 6H; with deuterated solvent being deuterated acetone. The target molecular formula for elemental analysis is C1. 43 H 33 Ti (%) = C: 86.25%, H: 5.38%. This indicates the successful synthesis of indenop-(1,2,3-cd)pyrene tribenzyl titanium, whose chemical structure is as follows:

[0087] Methylaluminoxane (B1#), triethylaluminum (B2#), N,N-dimethylaniline-tetra(pentafluorophenyl)borate (B3#), diphenylzinc (B4#), phenylsilane (B5#), and pentamethylcyclopentadienyltrimethoxytitanium are all commercially available.

[0088] The following examples and comparative examples all use a vertical single-shaft anchor-type stirred paddle reactor as the reactor.

[0089] Example 1

[0090] A method for synthesizing syndiotactic polystyrene includes the following steps:

[0091] (1) First, heat transfer oil is introduced into the main body of the heated reactor at 100°C, and vacuum is applied for 30 minutes. Then, nitrogen is introduced to fill the cavity of the main body of the reactor, and vacuum is applied again. This process is repeated three times.

[0092] (2) Then, adjust the reactor body to the set reaction temperature (see Table 1), and add 4500 g of styrene, 1250 g of o-dichlorobenzene, 1 mL of toluene solution of methylaluminoxane (containing 10 mmol of methylaluminoxane), 1 mL of toluene solution of N,N-dimethylaniline-tetra(pentafluorophenyl)borate (containing 0.2 mmol of N,N-dimethylaniline-tetra(pentafluorophenyl)borate) and 1 mL of toluene solution of inden(1,2,3-cd)pyrenetrimethyltitanium through the feed port. The detailed dosage is shown in Table 1. Stir for 1 min and continue to react for 1 h.

[0093] (3) After the reaction is completed, the jacket heat transfer oil temperature is kept at 150℃ and vacuum is applied for 1 hour. After the desizing is completed, the bottom discharge valve of the reactor is opened to obtain the dried product, i.e., syndiotactic polystyrene.

[0094] Examples 2-12

[0095] The difference between Examples 2-12 and Example 1 lies in the differences in raw materials and reaction temperature, as detailed in Table 1.

[0096] Comparative Example 1

[0097] The difference between this comparative example and Example 1 is that the main catalyst A1# is replaced with an equimolar amount of pentamethylcyclopentadienyltrimethoxytitanium.

[0098] Comparative Example 2

[0099] The difference between this comparative example and Example 1 is that the main catalyst A1# is replaced with an equimolar amount of pentamethylcyclopentadienyltrimethoxytitanium; the co-catalyst (B3#) is replaced with triisobutylaluminum and its molar amount is increased to 60 mmol; and the molar amount of B1# is increased to 60 mmol.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that the solvent o-dichlorobenzene is replaced with the same mass of toluene in this comparative example.

[0102] Comparative Example 4

[0103] The difference between this comparative example and Example 1 is that the reaction temperature in this comparative example is set to 120°C.

[0104] Table 1

[0105] Performance testing:

[0106] The syndiotacticity and number-average molecular weight of the syndiotactic polystyrene prepared by the methods of each embodiment and comparative example were determined, and the styrene conversion, swollen body content, and catalyst activity were calculated. The test methods are as follows:

[0107] (1) Syndiotacticity was characterized by carbon NMR spectroscopy using a Bruker DMX 500Hz instrument. The test samples were prepared by dissolving in deuterated o-dichlorobenzene. The chemical shifts of the syndiotactic structure were 145.1-145.3 ppm and the chemical shifts of the random structure were 144.8-146.0 ppm. Syndiotacticity = peak area of ​​syndiotactic structure / (peak area of ​​random structure + peak area of ​​syndiotactic structure).

[0108] (2) Molecular weight: Characterized by gel permeation chromatography (GPC) using an Agilent PL-GPC 220 instrument with a differential detector. Three PLgel 10µm MIXED-B LS 300*7.5mm columns were used in series. The mobile phase was 1,2,4-trichlorobenzene, the temperature was 150℃, and the flow rate was 1mL / min. The standard curve for GPC testing was determined using polystyrene with a narrow molecular weight distribution as a standard, and the number-average relative molecular weight (Mn) of the polymer was calculated. The syndiotactic polystyrene sample was dissolved in 1,2,4-trichlorobenzene to a concentration of 2-5 mg / mL, and filtered through a 450nm organic filter to remove insoluble impurities.

[0109] (3) Styrene monomer conversion rate = mass of polystyrene / mass of styrene feed × 100%.

[0110] (4) Swelling content = swelling mass / styrene feed mass × 100%, wherein the dried product passes through an 18-mesh (1mm mesh diameter) vibrating screen, wherein the powder passing through the screen is polystyrene, and the swelling is retained on the screen.

[0111] (5) Catalyst activity = product mass / molar amount of main catalyst, where catalyst activity refers to the mass of syndiotactic polystyrene generated per mole of catalyst.

[0112] The test results are shown in Table 2.

[0113] Table 2

[0114] Comparative Example 1 used the existing conventional main catalyst, pentamethylcyclopentadienyltrimethoxytitanium, which resulted in a very low styrene conversion rate in the preparation of syndiotactic polystyrene. Comparative Example 2 used a conventional metallocene catalyst system with pentamethylcyclopentadienyltrimethoxytitanium as the main catalyst. To improve catalytic activity, a co-catalyst was added in an excess of approximately 300 times compared to the main catalyst, but the styrene conversion rate remained low even at high temperatures. Comparative Example 3 used toluene as the solvent, resulting in a large-area swollen body with almost no powdered product. Comparative Example 4 set the reaction temperature to 120°C. Although a small amount of conversion occurred, the actual conversion rate and apparent activity were very low due to the inability to effectively dissolve the polymerization product at this temperature, leading to heterogeneous swelling. This also resulted in significant swelling, indicating that at high temperatures, using a specific solvent to dissolve the polymer to form a homogeneous system is crucial to avoid swelling and achieve high conversion rates.

[0115] As can be seen from Examples 1-12 and Comparative Examples 1-2, the composite catalyst of the present invention exhibits high catalytic activity at high temperatures of 130-170°C, with an activity ≥2×10⁻⁶. 7 The method yields g sPS / mol Ti, resulting in a styrene conversion rate ≥90% and a number-average molecular weight of 198,000 to 259,000 g / mol. Furthermore, in the reaction systems of Examples 1-12, the weight ratio of styrene to solvent is in the range of 1:(0.1-0.5), the styrene solid content in the system is ≥50%, classifying it as a high-solids-content or low-solvent system, and the content of swollen material is ≤0.1%. Therefore, the synthesis method of this invention effectively achieves high conversion rate, high catalytic activity, and high single-reactor yield under low solvent content during the production of syndiotactic polystyrene.

[0116] The main catalysts in Examples 1 and 6-7 were indeno(1,2,3-cd)pyrenetrimethyltitanium (A1#), indeno(1,2,3-cd)pyrenetriallyltitanium (A2#), and indeno(1,2,3-cd)pyrenetribenzyltitanium (A3#), respectively. The styrene conversion rate of the three main catalysts could reach more than 90%. Among them, indeno(1,2,3-cd)pyrenetrimethyltitanium had the best catalytic effect, while the catalytic effects of indeno(1,2,3-cd)pyrenetriallyltitanium (A2#) and indeno(1,2,3-cd)pyrenetribenzyltitanium (A3#) were comparable.

[0117] In Examples 1 and 11-12, the polymerization temperatures were 150℃, 130℃, and 170℃, respectively. At reaction temperatures between 130℃ and 170℃, the styrene conversion rate reached over 90%. Within this range, as the reaction temperature increased, the styrene conversion rate and catalyst activity first increased and then slightly decreased. This indicates that the polymerization reaction temperature of the present invention can be selected between 130℃ and 170℃, at which point the catalytic activity of the reaction system and the styrene conversion rate are both high. Furthermore, combined with the analyses of Examples 2 and 6 and Examples 3 and 7, the results show that the optimal temperature varies for different main catalysts. At the optimal temperature, a lower amount of co-catalyst can be used to obtain higher conversion rates and catalyst activity.

[0118] The results of Examples 1, 8, 9, and 10 show that different combinations of cocatalysts can lead to differences in activity; however, overall, high conversion rates, number-average molecular weights, and catalyst activities can be obtained. In Examples 1 and 9, the first-class cocatalysts were methylaluminoxane (B1#) and triethylaluminum (B2#), respectively, and the catalytic effects of these two first-class cocatalysts on the main catalyst were comparable. In Examples 1, 8, and 10, the second-class cocatalysts were N,N-dimethylaniline-tetra(pentafluorophenyl)borate (B3#), diphenylzinc (B4#), and phenylsilane (denoted as B5#), respectively. The styrene conversion rate and catalyst activity of Example 1 were higher than those of Examples 8 and 10, indicating that N,N-dimethylaniline-tetra(pentafluorophenyl)borate (B3#) had a better catalytic effect on the main catalyst.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite catalyst characterized in that, The composite catalyst comprises a main catalyst and a co-catalyst. The main catalyst has the chemical formula RTiX3, wherein R is inden(1,2,3-cd)pyrene or an inden(1,2,3-cd)pyrene containing substituents; and X is independently selected from halogen atoms, C 1-8 Alkyl, C 2-8 alkenyl, C 3-8 Alkenyl, C 1-8 Alkoxy, aryl, C 7-10 Aryl alkyl, C 7-10 The catalyst is any one of alkylaryl groups; the cocatalyst includes a first cocatalyst and a second cocatalyst; the first cocatalyst includes an alkylaluminum catalyst; the second cocatalyst includes at least one of a borate catalyst and a phenyl catalyst.

2. The composite catalyst of claim 1, wherein Includes at least one of the following: 1) The halogen atom is F, Cl, or Br; 2) said C 1-8 alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl; 3) said C 2-8 Alkynyl includes ethynyl, propynyl or butynyl; 4) said C 3-8 Alkenyl alkyl includes allyl, crotyl, or pentenyl. 5) said C 1-8 Alkoxy includes methoxy, ethoxy or propoxy; 6) The aryl group includes phenyl; 7) said C 7-10 Arylalkyl includes benzyl, phenethyl or phenylpropyl; 8) said C 7-10 Alkylaryl includes 4-methyl-phenyl, 4-ethyl-phenyl or 4-propyl-phenyl; 9) Substituents in indo(1,2,3-cd)pyrene containing substituents include C 1-8 alkyl, C 1-8 One of the alkoxy groups.

3. The composite catalyst according to claim 1 or 2, wherein The procatalyst comprises at least one of the following compounds:

4. The composite catalyst according to claim 1 or 2, wherein The preparation method of the main catalyst includes the following steps: (1) Add indene(1,2,3-cd)pyrene or indene(1,2,3-cd)pyrene-containing compounds with substituents to potassium bis(trimethylsilyl)amide in a solvent and react at 50-70°C for 7-9 hours; then add trimethylchlorosilane and react at room temperature for 1-3 hours; then add titanium tetrachloride and react at room temperature for 1-3 hours to obtain an intermediate product; (2) The intermediate product, solvent and X-ONa are mixed and reacted at 70-90°C for 5-7 hours to obtain the main catalyst; the X in X-ONa is the same as the X in the chemical formula RTiX3 of the main catalyst.

5. The composite catalyst of claim 4, wherein the metal oxide is selected from the group consisting of titanium oxide, zirconium oxide, and mixtures thereof. Includes at least one of the following: a. In step (1), the room temperature is 20-30℃; b. In step (1), the molar ratio of indeno(1,2,3-cd)pyrene or indeno(1,2,3-cd)pyrene compound containing substituents, bis(trimethylsilyl)amide potassium, trimethylchlorosilane, and titanium tetrachloride is indeno(1,2,3-cd)pyrene or indeno(1,2,3-cd)pyrene compound containing substituents: bis(trimethylsilyl)amide potassium: trimethylchlorosilane: titanium tetrachloride = 1:(0.9-1.2):(0.9-1.2):(0.9-1.2); c. In step (1), the solvent includes tetrahydrofuran; d. In step (1), the amount of indo(1,2,3-cd)pyrene or indo(1,2,3-cd)pyrene containing substituents is 2-10 mL of solvent containing 1 mmol of indo(1,2,3-cd)pyrene or indo(1,2,3-cd)pyrene containing substituents; e. In steps (1)-(2), the molar ratio of the indo(1,2,3-cd)pyrene or the indo(1,2,3-cd)pyrene compound containing substituents to the X-ONa is 1:(0.9-1.2); f. In step (2), the solvent includes toluene; g. In step (1), the amount of X-ONa used is 2-10 mL of solvent containing 1 mmol of X-ONa.

6. The composite catalyst of claim 1, wherein the metal oxide is selected from the group consisting of titanium oxide, zirconium oxide, and mixtures thereof. The molar ratio of the main catalyst to the co-catalyst is 1:(1-150).

7. The composite catalyst of claim 1, wherein the metal oxide is selected from the group consisting of titanium oxide, zirconium oxide, and mixtures thereof. The molar ratio of the first cocatalyst to the second cocatalyst is (1-50):

1.

8. The composite catalyst of claim 1, wherein the metal oxide is selected from the group consisting of titanium oxide, zirconium oxide, and mixtures thereof. The alkylaluminum catalyst is selected from at least one of triethylaluminum, tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, methylaluminoxane, and modified methylaluminoxane.

9. The composite catalyst as described in claim 1, characterized in that, Includes at least one of the following: A. The borate catalyst is selected from at least one of triphenylmethyl-tetra(pentafluorophenyl)borate, N,N-dimethylaniline-tetra(pentafluorophenyl)borate, and N,N-dimethylaniline-tetraphenylborate; B. The phenyl catalyst includes at least one of diphenylzinc and phenylsilane.

10. The use of the composite catalyst according to any one of claims 1 to 9 in the preparation of syndiotactic polystyrene.

11. A method for producing syndiotactic polystyrene, characterized by, Includes the following steps: Styrene, solvent, and the composite catalyst according to any one of claims 1 to 9 are added to a reactor to carry out a polymerization reaction to obtain the syndiotactic polystyrene; the polymerization reaction temperature is 130 to 170°C, and the solvent is a halobenzene or halohydrocarbon with a boiling point greater than 130°C.

12. The preparation method of syndiotactic polystyrene according to claim 11, wherein the solvent is toluene. The amount of the main catalyst used is 0.004 to 0.03 mmol / 1 mol styrene.

13. The method for preparing syndiotactic polystyrene as described in claim 11, characterized in that, Includes at least one of the following: I. The solvent is selected from at least one of o-dichlorobenzene, trichlorobenzene, and tetrachloroethane; II. The mass ratio of styrene to solvent is 1:(0.1-0.5); III. The syndiotactic polystyrene has a number average molecular weight of 2 x 10 5 ~ 3 x 10 5 g / mol.

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