A method of cyclization polymerization, catalysts used and methods of preparation

Abstract

The application discloses a cyclization polymerization method, characterized in that the method is used for cyclization polymerization reaction of a diene as raw material in the presence of a catalyst and a cocatalyst, the catalyst is a titanium-based catalyst with titanium supported on carbon dots (CDs) after silanization treatment, and the cocatalyst is an alkyl aluminum chloride.

Description

Technical Field

[0001] This invention relates to a cyclization polymerization method, the catalyst used, and the preparation method. More specifically, this invention relates to a method for diene cyclization polymerization catalyzed by a titanium-based catalyst supported on carbon dots (CDs), the catalyst used, and the preparation method. Background Technology

[0002] Dienes are important organic chemical raw materials and intermediates, with butadiene being a key component. Butadiene is one of the three major olefins produced during petrochemical production and is a widely used organic chemical raw material. Currently, it is mainly used in the production of polybutadiene rubber, such as styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, and chloroprene rubber. With the rapid development of science and technology and the continuous advancement of low-molecular-weight polymerization technologies for olefins, such as dimerization and trimerization, it is receiving increasing attention.

[0003] Existing diene cyclopolymerization catalytic systems are mainly homogeneous systems. After the reaction is completed, the catalyst needs to be quenched and removed by adding polar substances such as water and alcohol, which results in the removal of impurities and the introduction of new impurities. The catalyst cannot be recycled, and solid waste is generated.

[0004] To address the above issues, heterogeneous catalysts are a better choice. Nanomaterials can be compounded with active components to form heterogeneous catalysts, which hold promise for applications in diene cyclization polymerization. Nanomaterials refer to tiny carbon particles with dimensions in the nanometer range (1–100 nm). Similar to ordinary nanomaterials, they also possess unique properties such as quantum size effects, small size effects, and macroscopic quantum tunneling effects in optics, electricity, and magnetism. In 2004, tiny carbon nanoparticles smaller than 10 nm, discovered during the purification of monolayer carbon nanotubes using electrophoresis, were first named carbon dots (CDs), representing a novel type of small-sized carbon nanomaterial. Summary of the Invention

[0005] The inventors discovered that modifying carbon dots (CDs) and then supporting them with titanium compounds to prepare heterogeneous catalysts, using alkylaluminum chloride as a co-catalyst, can effectively catalyze the diene cyclization polymerization reaction. Based on this, the present invention was formed.

[0006] The purpose of this invention is to provide a diene cyclization polymerization method that differs from existing technologies, and to provide the catalyst used in this method and its preparation method.

[0007] To achieve the above objectives, a first aspect of the present invention provides a cyclization polymerization method, characterized in that the method involves a cyclization polymerization reaction using a diene as a raw material in the presence of a catalyst and a co-catalyst, wherein the catalyst is a titanium-based catalyst supported on carbon dots (CDs) after silanization treatment, and the co-catalyst is alkyl aluminum chloride.

[0008] In the cyclization polymerization method, the alkyl aluminum chloride is preferably sesquiethyl aluminum chloride or diethylaluminum chloride. The weight ratio of the co-catalyst to the heterogeneous catalyst is 5-40:1, preferably 10-25:1. The diene is a straight-chain diene with C4 to C8 carbon atoms, preferably butadiene.

[0009] To achieve the above objectives, a second aspect of the present invention provides a heterogeneous catalyst, namely a titanium-based catalyst, characterized in that the catalyst consists of silanized carbon dots (CDs) and titanium supported on the silanized carbon dots (CDs), wherein the titanium content is 1-10% based on the mass of the catalyst, preferably 2-8%.

[0010] To achieve the above objectives, a third aspect of the present invention provides a method for preparing the above-mentioned heterogeneous catalyst, i.e., a titanium-based catalyst, characterized in that the method comprises the following steps:

[0011] a. First, react carbon dots (CDs) with a silanizing agent and optional light aromatic hydrocarbons to obtain silanized carrier carbon dots (CDs) as a carrier; b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, react the carrier carbon dots (CDs), TiCl4, and light aromatic hydrocarbons.

[0012] More specifically, in the method for preparing the catalyst provided by the present invention, step a is to mix carbon dots CDs with a silanizing agent and optional light aromatic hydrocarbons, stir and react at 50-90°C for 2-12 hours, filter and dry to obtain silanized carbon dots CDs as a support, wherein the weight ratio of carbon dots CDs, silanizing agent and light aromatic hydrocarbons is 1:1-10:0-100.

[0013] More specifically, in the method for preparing the catalyst provided by the present invention, step b involves mixing the support, TiCl4, and light aromatic hydrocarbons under anhydrous and oxygen-free reaction conditions and nitrogen protection, stirring the mixture at 30-60°C for 5-30 hours, and then separating, washing, and drying to obtain the titanium-based catalyst. The weight ratio of TiCl4 to the support is 0.5-20, preferably 2-15, and the weight ratio of light aromatic hydrocarbons to the support is 5-25.

[0014] In the method for preparing the catalyst provided by the present invention, preferably, the light aromatic hydrocarbon mentioned in steps a and b can be selected from benzene, toluene, ethylbenzene, xylene, etc.; more preferably, the light aromatic hydrocarbon is toluene.

[0015] In the method for preparing the catalyst provided by this invention, the primary particles of carbon dots (CDs) have an average particle size of 5-10 nm, a carbon content of 50-80%, and the balance being oxygen. The molar ratio of surface CO to surface C=O is 1-5. Carbon dots (CDs) can be commercially available or prepared in-house. This invention does not impose any special restrictions on the source of carbon dots (CDs), as long as the above requirements are met.

[0016] In the method for preparing the catalyst provided by this invention, the silanizing agent has the general formula R″R′N-(CH2)n-Si-A′A″A″′, wherein R′ and R″ are both H, or one of R′ and R″ is H and the other is a C1-C4 alkyl group, and A′, A″, and A″′ are all methoxy or all ethoxy, or when any one of A′, A″, and A″′ is methyl or ethyl, the other two are all methoxy, all ethoxy, or respectively methoxy and ethoxy, and n is 1, 2, 3, or 4; more preferably, R′ and R″ are both H. Preferably, the silanizing agent in step a is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, or N-methyl-3-aminopropyltrimethoxysilane.

[0017] This invention prepares a heterogeneous titanium-based catalyst by modifying carbon dots with a silanizing agent and then supporting a titanium-based compound. This catalyst, along with an alkylaluminum chloride co-catalyst, co-catalyzes the cyclization polymerization of dienes. After the cyclization polymerization reaction is complete, the catalyst is filtered or centrifuged under anhydrous and oxygen-free conditions and reused without significant change in catalytic performance. This invention overcomes the various drawbacks of existing homogeneous systems. The solid catalyst can be recovered through simple filtration or centrifugation for recycling, with no significant change in selectivity, thus reducing solid waste. Detailed Implementation

[0018] The present invention will be further illustrated by the following examples, but these examples are not intended to limit the invention.

[0019] Examples 1-4 illustrate the heterogeneous catalyst and its preparation method provided by the present invention.

[0020] Example 1

[0021] a. Under stirring conditions, 5g of carbon dots CDs (Shanghai Xiwang Technology Co., Ltd., with an average particle size of 8nm, carbon content of 63.1%, and the remainder being oxygen, and a molar ratio of surface CO to surface C=O of 1.8, the same below), 20g of 3-aminopropyltrimethoxysilane H2N(CH2)3Si(OCH3)3 and 50g of toluene were mixed and stirred at 60℃ for 8h. The solid was filtered out and dried at 120℃ to obtain the carrier carbon dots CDs.

[0022] b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, 6g of carrier carbon dots (CDs), 20g of TiCl4 and 180g of toluene were mixed and stirred at 30°C for 24h. The mixture was filtered, washed three times with hexane, and dried to obtain a heterogeneous titanium-based catalyst, designated HeC1, with a titanium content of 7.6%.

[0023] Example 2

[0024] 5g of carbon dots CDs, 20g of 3-aminopropyltriethoxysilane H2N(CH2)3Si(OC2H5)3 and 100g of toluene were mixed and stirred at 70℃ for 6h. The solid was filtered out and dried at 120℃ to obtain the carrier carbon dots CDs.

[0025] d. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, 6g of carrier carbon dots (CDs), 15g of TiCl4 and 200g of toluene were mixed and stirred at 40°C for 18h. The mixture was filtered, washed three times with hexane, and dried to obtain a heterogeneous titanium-based catalyst, designated HeC2, with a titanium content of 7.8%.

[0026] Example 3

[0027] 10g of carbon dots CDs, 20g of 3-aminopropylmethyldiethoxysilane H2N(CH2)3Si(CH2)(OC2H5)2 and 70g of toluene were mixed and stirred at 80℃ for 4h. The solid was filtered out and dried at 120℃ to obtain the carrier carbon dots CDs.

[0028] b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, 6g of carrier carbon dots (CDs), 20g of TiCl4 and 250g of toluene were mixed and stirred at 50°C for 10h. The mixture was filtered, washed three times with hexane, and dried to obtain a heterogeneous titanium-based catalyst, designated HeC3, with a titanium content of 8.1%.

[0029] Example 4

[0030] 10g of carbon dots CDs, 10g of N-methyl-3-aminopropyltrimethoxysilane CH3NH(CH2)3Si(OCH3)3 and 50g of toluene were mixed and stirred at 90℃ for 5h. The solid was filtered out and dried at 120℃ to obtain the carrier carbon dots CDs.

[0031] b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, 6g of carrier carbon dots (CDs), 16g of TiCl4 and 150g of toluene were mixed and stirred at 60°C for 5h. The mixture was filtered, washed three times with hexane, and dried to obtain a heterogeneous titanium-based catalyst, designated HeC4, with a titanium content of 5.9%.

[0032] Example 5

[0033] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention and the effect of reusing the catalyst.

[0034] The butadiene cyclization polymerization reaction was carried out in a 1L Paarr reactor.

[0035] The gas inside the reactor was first purged three times with nitrogen. Then, under nitrogen protection, 500 mL of toluene, 20 g of sesquiethylaluminum chloride, and 1 g of heterogeneous catalyst HeCl were added to the reactor. Stirring was started, and 1,3-butadiene was continuously introduced. The reaction was maintained at 65 °C and 0.2 MPa for 4 hours. After the reaction was complete, the mixture was filtered under nitrogen protection. The resulting solid was designated Re-HeCl and stored under nitrogen protection. The reaction was terminated by adding methanol to the resulting liquid. The product was then distilled to obtain the fraction composition.

[0036] 1,5,9-Cyclododecanetriene, abbreviated as CDT; dimerized and cyclized to form 1,5-cyclooctadiene, abbreviated as COD; 4-Vinylcyclohexene, abbreviated as VCH.

[0037] CDT selectivity = (mass of CDT in the product / total mass of the product) × 100%;

[0038] COD selectivity = (mass of COD in the product / total mass of the product) × 100%;

[0039] VCH selectivity = (mass of VCH in the product / total mass of the product) × 100%.

[0040] The selectivity for CDT was 56%, for COD 38%, and for VCH 5%.

[0041] Re-HeC1 was filtered under nitrogen protection, washed three times with hexane, and dried. Then, following the cyclization polymerization method described above, Re-HeC1 was used instead of HeC1 for the 1,3-butadiene cyclization reaction. The reaction product was treated by distillation to obtain the following fractions: CDT selectivity 56%, COD selectivity 36%, and VCH selectivity 8%.

[0042] Example 6

[0043] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention and the effect of reusing the catalyst.

[0044] Same as Example 5, except that HeC2 is used as the catalyst.

[0045] The selectivity of CDT was 52%, that of COD was 44%, and that of VCH was 4%.

[0046] Re-HeC2 was used instead of HeC2 for the 1,3-butadiene cyclopolymerization reaction, with CDT selectivity of 53%, COD selectivity of 43%, and VCH selectivity of 4%.

[0047] Example 7

[0048] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention and the effect of reusing the catalyst.

[0049] Same as Example 5, except that HeC3 is used as the catalyst.

[0050] CDT selectivity was 50%, COD selectivity was 44%, and VCH selectivity was 6%.

[0051] Re-HeC3 was used instead of HeC3 for the 1,3-butadiene cyclopolymerization reaction, with a CDT selectivity of 49%, a COD selectivity of 46%, and a VCH selectivity of 5%.

[0052] Example 8

[0053] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention and the effect of reusing the catalyst.

[0054] Same as Example 5, except that HeC4 is used as the catalyst.

[0055] The selectivity of CDT was 53%, that of COD was 44%, and that of VCH was 3%.

[0056] Re-HeC4 was used instead of HeC4 for the 1,3-butadiene cyclopolymerization reaction, with a CDT selectivity of 52%, a COD selectivity of 47%, and a VCH selectivity of 1%.

[0057] Example 9

[0058] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention.

[0059] Same as Example 5, except that the weight ratio of the co-catalyst and the heterogeneous catalyst is changed to 30:1.

[0060] The selectivity for CDT was 51%, for COD 41%, and for VCH 8%.

[0061] Example 10

[0062] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention.

[0063] Same as Example 5, except that the co-catalyst is replaced with diethylaluminum chloride.

[0064] The selectivity for CDT was 55%, for COD 43%, and for VCH 2%.

[0065] Example 11

[0066] This embodiment illustrates the butadiene cyclization polymerization method provided by the present invention.

[0067] Same as Example 5, except that the cyclization polymerization temperature is changed to 80°C.

[0068] The selectivity for CDT was 61%, for COD 28%, and for VCH 11%.

Claims

1. A cyclization polymerization method, characterized in that, This method involves a cyclization polymerization reaction using a diene as a raw material in the presence of a catalyst and a co-catalyst. The catalyst is a titanium-based catalyst supported on silanized carbon dots (CDs), and the co-catalyst is alkylaluminum chloride. The titanium-based catalyst supported on silanized carbon dots (CDs) consists of silanized carbon dots (CDs) and titanium supported on them. Based on catalyst mass, the titanium content is 1-10%, and the titanium-based catalyst is prepared by a method including the following steps: a. Mix carbon dot CDs with a silanizing agent and optionally added light aromatic hydrocarbons, and stir the mixture at 50-90℃ for 2-12 hours. Filter and dry to obtain silanized carbon dot CDs as a support. The weight ratio of carbon dot CDs, silanizing agent, and light aromatic hydrocarbons is 1:1-10:0-100. The silanizing agent has the general formula R. ′′ R ′ N-(CH2)n-Si-A ′ A ′′ A ′′′ , wherein, the R ′ and the R ′′ Simultaneously H or the aforementioned R ′ and the R ′′ One of them is H and the other is a C1-C4 alkyl group, wherein A ′ A ′′ A ′′′ All are methoxy or all are ethoxy, and n is 1, 2, 3 or 4; b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, the support, TiCl4 and light aromatic hydrocarbons are mixed and stirred at 30-60°C for 5-30 hours. The mixture is then separated, washed and dried to obtain the titanium-based catalyst.

2. The cyclization polymerization method according to claim 1, characterized in that, The alkylaluminum chloride is sesquiethylaluminum chloride or diethylaluminum chloride; the diene is a straight-chain diene with C4 to C8 carbon atoms.

3. The cyclization polymerization method according to claim 1, characterized in that, The diene is butadiene.

4. The cyclization polymerization method according to claim 1 or 2, characterized in that, The weight ratio of the co-catalyst to the catalyst is 5-40:

1.

5. The cyclization polymerization method according to claim 1 or 2, characterized in that, The weight ratio of the co-catalyst to the catalyst is 10-25:

1.

6. The cyclization polymerization method according to claim 1, characterized in that, The silanizing agent mentioned in step a is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-methyl-3-aminopropyltrimethoxysilane.

7. A titanium-based catalyst, characterized in that, The catalyst consists of silanized carbon dots (CDs) and titanium supported on the silanized carbon dots (CDs), with a titanium content of 1-10% based on catalyst mass. This titanium-based catalyst is prepared by a method comprising the following steps: a. Mix carbon dot CDs with a silanizing agent and optionally added light aromatic hydrocarbons, and stir the mixture at 50-90℃ for 2-12 hours. Filter and dry to obtain silanized carbon dot CDs as a support. The weight ratio of carbon dot CDs, silanizing agent, and light aromatic hydrocarbons is 1:1-10:0-100. The silanizing agent has the general formula R. ′′ R ′ N-(CH2)n-Si-A ′ A ′′ A ′′′ , wherein, the R ′ and the R ′′ Simultaneously H or the aforementioned R ′ and the R ′′ One of them is H and the other is a C1-C4 alkyl group, wherein A ′ A ′′ A ′′′ All are methoxy or all are ethoxy, where n is 1, 2, 3 or 4; or the silanizing agent is 3-aminopropylmethyldiethoxysilane; b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, the support, TiCl4 and light aromatic hydrocarbons are mixed and stirred at 30-60°C for 5-30 hours. The mixture is then separated, washed and dried to obtain the titanium-based catalyst.

8. The catalyst according to claim 7, characterized in that, Based on catalyst quality, the titanium content is 2-8%.

9. The catalyst according to claim 7, characterized in that, The silanizing agent mentioned in step a is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-methyl-3-aminopropyltrimethoxysilane.

10. A method for preparing a titanium-based catalyst, characterized in that, The method includes the following steps: a. Mix carbon dot CDs with a silanizing agent and optionally added light aromatic hydrocarbons, and stir the mixture at 50-90℃ for 2-12 hours. Filter and dry to obtain silanized carbon dot CDs as a support. The weight ratio of carbon dot CDs, silanizing agent, and light aromatic hydrocarbons is 1:1-10:0-100. The silanizing agent has the general formula R. ′′ R ′ N-(CH2)n-Si-A ′ A ′′ A ′′′ , wherein, the R ′ and the R ′′ Simultaneously H or the aforementioned R ′ and the R ′′ One of them is H and the other is a C1-C4 alkyl group, wherein A ′ A ′′ A ′′′ All are methoxy or all are ethoxy, where n is 1, 2, 3 or 4; or the silanizing agent is 3-aminopropylmethyldiethoxysilane; b. Under anhydrous and oxygen-free reaction conditions and nitrogen protection, the support, TiCl4 and light aromatic hydrocarbons are mixed and stirred at 30-60°C for 5-30 hours. The mixture is then separated, washed and dried to obtain the titanium-based catalyst.

11. The preparation method according to claim 10, characterized in that, The carbon dots (CDs) have an average particle size of 5-10 nm, a carbon content of 50-80%, and the remainder is oxygen. The molar ratio of surface CO to surface C=O is 1-5.

12. The preparation method according to claim 10, characterized in that, In step b, the weight ratio of TiCl4 to the support is 0.5-20, and the weight ratio of light aromatic hydrocarbon to the support is 5-25.

13. The preparation method according to claim 10, characterized in that, In step b, the weight ratio of TiCl4 to the carrier is 1-15.

14. The preparation method according to claim 10, characterized in that, In step b, the weight ratio of TiCl4 to the carrier is 2-5.

15. The preparation method according to claim 10, characterized in that, The light aromatic hydrocarbons mentioned in steps a and b are selected from one or more of benzene, toluene, ethylbenzene, and xylene.

16. The preparation method according to claim 15, characterized in that, The light aromatic hydrocarbon is toluene.

17. The preparation method according to claim 10, characterized in that, The silanizing agent mentioned in step a is one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-methyl-3-aminopropyltrimethoxysilane.