A method for preparing a supported lewis acid catalyst and a method for preparing norbornene

Abstract

The application discloses a method for preparing a supported Lewis acid catalyst and a method for preparing norbornene. The method for preparing the catalyst comprises the following steps: (1) synthesizing an ionic covalent organic framework (iCOF) by one-step interfacial polymerization of a polyaldehyde monomer and an ionic functional group-containing polyamine monomer; and (2) loading metal ions with catalytic activity into the iCOF framework by ion exchange to obtain a supported Lewis acid catalyst M@iCOF. The catalyst is used for catalyzing Diels-Alder reaction of cyclopentadiene and ethylene to synthesize norbornene, reaction time is shortened, high-temperature and high-pressure reaction conditions are avoided, device construction cost is saved, and industrialization is more facilitated.

Description

Technical Field

[0001] This invention relates to a method for preparing iCOFs-supported Lewis acid catalysts and their application in the synthesis of norbornene. Background Technology

[0002] Cyclic olefin copolymers (COCs) possess excellent transparency, low birefringence, superior heat resistance, chemical resistance, and extremely low dielectric constant, making them widely used in optics and electronics. Norbornene (NB) is an important monomer in COC synthesis, typically prepared by the Diels-Alder addition of dicyclopentadiene (DCPD) and ethylene. This reaction is highly exothermic, and DCPD decomposes to form cyclopentadiene (CPD) during the reaction. The reaction pressure is often above 5 MPa, making the reaction prone to runaway and posing safety hazards.

[0003] Chinese patent CN104262074B discloses a process for producing norbornene, which involves cracking dicyclopentadiene with hydrogen to obtain cyclopentadiene. The cyclopentadiene is then mixed with ethylene and introduced into a fixed-bed reactor. The reaction temperature is 310-325℃, the pressure is 10-30 MPa, the molar ratio of ethylene to cyclopentadiene is 4.4-5.5:1, and the reaction time is 4-10 s. This method mitigates the carbonization problem of dicyclopentadiene cracking, but the operating temperature and pressure are still high. Chinese patent CN104692993A discloses a method for synthesizing norbornene using a microchannel reactor. First, a dicyclopentadiene solution is introduced into the reaction channel through one inlet. Then, ethylene is introduced into the reaction section through the first inlet. The reaction temperature is 180-300℃, the pressure is 5-30 MPa, the residence time is 0.5-10 minutes, the molar ratio of ethylene to dicyclopentadiene is 1-5:1, the cyclopentadiene conversion rate is 99.7%, and the norbornene selectivity is 99.5%. This patented reactor is designed with multiple inlets for segmented feeding and uses solvent dilution to reduce the reactant concentration in the reaction system, which increases the safety of the reaction to some extent. However, it still maintains a relatively high temperature and pressure, posing certain potential risks.

[0004] Existing technologies have not solved the problem of excessive internal pressure or temperature in the reactor, posing significant safety hazards. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for preparing iCOFs-supported Lewis acid catalysts and their application in the synthesis of norbornene, thereby resolving the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a supported Lewis acid catalyst includes the following steps:

[0008] (1) Ionic covalent organic frameworks iCOFs were synthesized in one step by interfacial polymerization using polyaldehyde monomers and polyamine monomers with ionic functional groups.

[0009] (2) Catalysts M@iCOFs loaded with Lewis acids are obtained by loading catalytically active metal ions into the iCOFs framework through ion exchange.

[0010] As a preferred embodiment, the iCOFs are prepared by organic-aqueous interfacial polymerization, the raw materials including polyaldehyde monomers activated by Brønsted acid in the organic phase and polyamine monomers with ionic functional groups in the aqueous phase, wherein the Brønsted acid is a fatty acid that is insoluble or slightly soluble in water.

[0011] As a preferred embodiment, the molar ratio of the polyaldehyde monomer to the polyamine monomer is 0.8-1.2:0.8-1.2.

[0012] As a preferred embodiment, the Brønsted acid includes, but is not limited to, heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid.

[0013] As a preferred embodiment, the ionic functional groups of the polyamine monomer include, but are not limited to, sulfonic acid groups, phosphate groups, and carboxylic acid groups.

[0014] As a preferred embodiment, the polyamine monomer includes, but is not limited to, one or more of 2,5-diaminobenzenesulfonic acid, 2,5-diaminobenzoic acid, 2,5-diaminophenylphosphonic acid, 4,4′-diamino-[1,1′-biphenyl]-3,3′-disulfonic acid, 3,5-dihydrazylcarbonylbenzenesulfonic acid, 3,5-dihydrazylcarbonylbenzoic acid, and 3,5-dihydrazylcarbonylphenylphosphonic acid.

[0015] As a preferred embodiment, the polyaldehyde monomer includes, but is not limited to, one or more of 1,3,5-trihydroxytrimethylbenzaldehyde and pyromellitic methylbenzaldehyde.

[0016] As a preferred option, in step (1), the reaction temperature is 16-25℃ and the reaction time is 48-96h.

[0017] As a preferred option, in step (2), the mass ratio of iCOFs to Lewis acid is 100:1-5.

[0018] As a preferred embodiment, in step (2), the Lewis acid is selected from one or more of zinc chloride, ferric chloride, and titanium tetrachloride.

[0019] As a preferred option, in step (2), the ion exchange temperature is 20-40℃ and the time is 8-12h.

[0020] As a preferred embodiment, the catalyst described in this invention is used to react cyclopentadiene with ethylene to prepare norbornene.

[0021] A method for preparing norbornene includes the following steps: reacting cyclopentadiene with ethylene in the presence of a catalyst and a solvent to obtain norbornene, wherein the catalyst is the catalyst described in this invention.

[0022] As a preferred embodiment, in the method for preparing norbornene, the mass ratio of cyclopentadiene to catalyst is 100:0.1-0.5.

[0023] As a preferred embodiment, the reaction temperature in the method for preparing norbornene is 140-170℃.

[0024] As a preferred embodiment, the reaction pressure in the method for preparing norbornene is 0.1-2 MPa.

[0025] As a preferred embodiment, in the method for preparing norbornene, the molar ratio of cyclopentadiene to ethylene is 1:1-1.05.

[0026] Compared with existing technologies, the technical solution of this invention has the following advantages: In industrial production processes, in order to improve the conversion rate and selectivity of the reaction, an excess of ethylene is used. However, a large amount of excess ethylene leads to high reaction pressure, mostly above 10 MPa. High reaction pressure increases equipment investment and operational risks. The catalyst used in this invention can reduce the reaction temperature and pressure, resulting in milder reaction conditions, which is beneficial for industrial production. Detailed Implementation

[0027] The present invention will be further illustrated by specific embodiments below. It should be noted that the embodiments below are for illustrative purposes only, and the content of the present invention is not limited thereto.

[0028] The gas chromatograph was an Agilent 7820A with a capillary column (DP-5, 30m × 0.25mm × 0.25μm). A two-stage temperature program was used: an initial temperature of 80℃, held for 2 minutes, then increased to 120℃ at a rate of 5℃ / min; followed by an increase to 260℃ at a rate of 15℃ / min, held for 22 minutes. High-purity N2 was used as the carrier gas with a split ratio of 50:1. The injection temperature was 290℃, the detector was an FID (Fluid Imaging Detector) with a detector temperature of 300℃, and the injection volume was 0.2μL.

[0029] Example 1:

[0030] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminobenzenesulfonic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top of the aqueous phase solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs.

[0031] The prepared iCOFs aqueous dispersion was placed in a 200mL flask, 40mg of anhydrous ferric chloride was added, and the mixture was stirred at room temperature for 12h. The upper solid was filtered, washed three times with ethanol, and then dried to obtain the Fe@iCOFs catalyst.

[0032] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of catalyst was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 98.2%, the NB selectivity was 96.6%, and the polymer content was 0.9wt%.

[0033] Example 2:

[0034] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminobenzenesulfonic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top of the aqueous phase solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs.

[0035] The prepared iCOFs aqueous dispersion was placed in a 200mL flask, 40mg of titanium tetrachloride was added, and the mixture was stirred at room temperature for 12h. The upper solid was filtered, washed three times with ethanol, and then dried to obtain the Ti@iCOFs catalyst.

[0036] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of catalyst was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 97.9%, the NB selectivity was 96.2%, and the polymer content was 0.7wt%.

[0037] Example 3:

[0038] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminobenzenesulfonic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top of the aqueous phase solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs.

[0039] The prepared iCOFs aqueous dispersion was placed in a 200mL flask, 20mg of anhydrous ferric chloride was added, and the mixture was stirred at room temperature for 12h. The upper solid was filtered, washed three times with ethanol, and then dried to obtain the Fe@iCOFs catalyst.

[0040] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of catalyst was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 95.5%, the NB selectivity was 97.2%, and the polymer content was 0.4wt%.

[0041] Example 4:

[0042] The Fe@iCOFs catalyst was prepared using the same method as in Example 1. 500 g of a 20 wt% dicyclopentadiene toluene solution was added to a 1 L reactor, along with 0.3 g of catalyst. Stirring was started, and the temperature was raised to 170 °C. Ethylene was introduced into the system, maintaining a system pressure of 4 MPa. The reaction was carried out for 5 h, resulting in a cyclopentadiene conversion of 98.5%, a NB selectivity of 95.6%, and a polymer content of 1.6 wt%.

[0043] Example 5:

[0044] The Fe@iCOFs catalyst was prepared using the same method as in Example 1. 500 g of a 20 wt% dicyclopentadiene toluene solution was added to a 1 L reactor, along with 0.3 g of catalyst. Stirring was started, and the temperature was raised to 150 °C. Ethylene was introduced into the system, maintaining a system pressure of 2 MPa. The reaction was carried out for 5 h, resulting in a cyclopentadiene conversion of 95.2%, a NB selectivity of 97.7%, and a polymer content of 0.6 wt%.

[0045] Example 6:

[0046] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminobenzoic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top of the aqueous phase solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs.

[0047] The prepared iCOFs aqueous dispersion was placed in a 200mL flask, 40mg of anhydrous ferric chloride was added, and the mixture was stirred at room temperature for 12h. The upper solid was filtered, washed three times with ethanol, and then dried to obtain the Fe@iCOFs catalyst.

[0048] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of catalyst was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 93.5%, the NB selectivity was 96.7%, and the polymer content was 0.6wt%.

[0049] Example 7:

[0050] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminophenylphosphonic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top of the aqueous phase solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs.

[0051] The prepared iCOFs aqueous dispersion was placed in a 200mL flask, 40mg of anhydrous ferric chloride was added, and the mixture was stirred at room temperature for 12h. The upper solid was filtered, washed three times with ethanol, and then dried to obtain the Fe@iCOFs catalyst.

[0052] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of catalyst was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 98.4%, the NB selectivity was 96.1%, and the polymer content was 1.2wt%.

[0053] Comparative Example 1:

[0054] 10 mmol of 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde was dissolved in 100 mL of octanoic acid and sonicated for half an hour to obtain an organic phase solution of the aldehyde monomer. 10 mmol of 2,5-diaminobenzenesulfonic acid was dissolved in 100 mL of deionized water and sonicated for half an hour to obtain an aqueous phase solution of the amine monomer. The organic phase solution was then slowly added to the top layer of the aqueous solution. The reaction was carried out at 20 °C for 72 hours. The upper oil phase solution was removed, and the lower aqueous phase solution was dialyzed in a dialysis bag for 72 hours, with multiple water changes to ensure complete dialysis purification, yielding an aqueous dispersion of iCOFs. The iCOFs aqueous dispersion was lyophilized to obtain iCOFs solid powder.

[0055] 500g of a 20wt% dicyclopentadiene toluene solution was added to a 1L reactor. 0.3g of COFs was added to the system, stirring was started, the temperature was raised to 150℃, ethylene was introduced into the system, the system pressure was maintained at 4MPa, and the reaction was carried out for 5 hours. The cyclopentadiene conversion rate was 53.7%, the NB selectivity was 90.3%, and the polymer content was 8.3wt%.

[0056] Comparative Example 2:

[0057] Add 500g of a 20wt% dicyclopentadiene toluene solution to a 1L reactor, start stirring, heat to 210℃, introduce ethylene into the system, maintain the system pressure at 10MPa, react for 5h, the cyclopentadiene conversion rate is 96%, the NB selectivity is 83.7%, and the polymer content is 12wt%.

[0058] The above description is merely an example of the embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a supported Lewis acid catalyst, comprising the following steps: (1) Ionic covalent organic frameworks iCOFs were synthesized in one step by interfacial polymerization using polyaldehyde monomers and polyamine monomers with ionic functional groups. (2) Catalysts M@iCOFs loaded with Lewis acids are obtained by loading catalytically active metal ions into the iCOFs framework through ion exchange.

2. The method according to claim 1, characterized in that, The iCOFs are prepared by organic-aqueous interfacial polymerization. The raw materials include polyaldehyde monomers activated by Brønsted acid in the organic phase and polyamine monomers with ionic functional groups in the aqueous phase. The Brønsted acid is a fatty acid that is insoluble or slightly soluble in water.

3. The method according to claim 1 or 2, characterized in that, The molar ratio of the polyaldehyde monomer to the polyamine monomer is 0.8-1.2:0.8-1.

2.

4. The method according to any one of claims 1-3, characterized in that, The Brønsted acid comprises one or more of heptanoic acid, octanoic acid, nonanoic acid, and decanoic acid.

5. The method according to any one of claims 1-4, characterized in that, The ionic functional groups of the polyamine monomer include one or more of the following: sulfonic acid group, phosphate group, and carboxylic acid group.

6. The method according to any one of claims 1-5, characterized in that, The polyamine monomers include one or more of 2,5-diaminobenzenesulfonic acid, 2,5-diaminobenzoic acid, 2,5-diaminophenylphosphonic acid, 4,4′-diamino-[1,1′-biphenyl]-3,3′-disulfonic acid, 3,5-dihydrazylcarbonylbenzenesulfonic acid, 3,5-dihydrazylcarbonylbenzoic acid, and 3,5-dihydrazylcarbonylphenylphosphonic acid.

7. The method according to any one of claims 1-6, characterized in that, The polyaldehyde monomers include one or more of 1,3,5-trihydroxytrimethylbenzaldehyde and pyromellitic methylbenzaldehyde.

8. The method according to any one of claims 1-7, characterized in that, In step (2), the mass ratio of iCOFs to Lewis acid is 100:1-5; and / or, the Lewis acid is selected from one or more of zinc chloride, ferric chloride, and titanium tetrachloride.

9. A method for preparing norbornene, comprising the following steps: Cyclopentadiene reacts with ethylene in the presence of a catalyst and solvent prepared by any one of claims 1-8 to obtain norbornene.

10. The method according to claim 9, characterized in that, The mass ratio of cyclopentadiene to catalyst is 100:0.1-0.5.