A method for recovering a norbornene process by-product and a method for producing norbornene

Abstract

The present application relates to a recovery method of norbornene process by-product, which is prepared by using ethylene as an addition reagent, and reacting the by-product of norbornene preparation process in a stirred tank reactor in an inert solvent to obtain norbornene. The recovery process of the present application can improve the overall yield of norbornene and reduce the raw material consumption. The present application also relates to a norbornene production method comprising the aforementioned by-product recovery method. By introducing the innovative recovery process, the main reaction process of norbornene preparation can reduce the reaction pressure and obtain a high TCD / NB product ratio. The method of the present application has the advantages of good selectivity, high yield, high safety, less waste liquid, etc., and is convenient for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, specifically relating to a method for recovering byproducts of norbornene production and a method for producing norbornene. Background Technology

[0002] Norbornene (NB) is prepared by the addition reaction of cyclopentadiene (CPD) or dicyclopentadiene (DCPD) with ethylene, while tetracyclododecene (TCD) is obtained by further addition reaction of NB with CPD. 97% norbornene is used in the synthesis of COC / COP resins, and tetracyclododecene is the monomer for synthesizing lens-grade COC. COP / COC, as a high-performance thermoplastic engineering plastic, is widely used in pharmaceutical packaging, optical lenses, display polarizers, optical films, and medical optical components.

[0003] Existing literature reports numerous methods for synthesizing nano-nitrogen (NB). To improve yield, most processes involve high reaction pressures. For example, patent CN102249839A uses reaction pressures as high as 15-25 MPa to achieve a selectivity of 97%, resulting in harsh reaction conditions, demanding equipment, and a high degree of process risk. In particular, cyclopentadiene, the raw material for NB synthesis, is highly unstable and prone to polymerization at high temperatures, posing a significant risk of overheating and overpressure. The synthesis of tetracyclododecene is rarely reported in the literature; most studies rely on it as a byproduct of NB synthesis. A one-step method using NB and DCPD to prepare TCD yields only around 87%, generating large amounts of cyclopentadiene polymers as byproducts, as well as polymers formed from NB and CPD. Therefore, the NB preparation process needs to maximize the selectivity of the TCD product.

[0004] CN104262074A reported the synthesis of norbornene by preparing cyclopentadiene from cycloolefin polymers through cracking under a hydrogen atmosphere. However, the required reaction temperature is high, at 300-320℃, which results in low safety and is not conducive to industrial production. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the present invention aims to provide a method for recovering heavy component byproducts in the production process of norbornene or tetracyclododecene. Using ethylene as the addition gas, the active CPD generated from the cracking of polymer byproducts is promptly added to ethylene to form NB, thereby improving the overall NB yield, reducing unit consumption, and decreasing the amount of process waste liquid.

[0006] Another objective of this invention is to provide a method for producing norbornene that includes the above-mentioned byproduct recovery process, wherein the main process of norbornene production from DCPD and ethylene no longer requires excessively high ethylene pressure, while increasing the selectivity of TCD.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for recovering a byproduct of norbornene processing includes the following steps:

[0009] 1) Add an inert organic solvent and the waste liquid from the norbornene process to the reactor, then introduce ethylene into the reactor to reach a certain pressure and maintain it constant. After reacting for a period of time, the reaction solution is obtained.

[0010] 2) The reaction solution obtained in step 1) is separated into high-purity norbornene by distillation.

[0011] In one specific implementation, the by-product waste liquid from the norbornene process is a heavy component by-product of the preparation of norbornene or tetracyclododecene by the liquid phase method; preferably, the by-product waste liquid contains a cyclic olefin polymer of at least one of the structures of Formula 1 to Formula 5.

[0012]

[0013] In one specific implementation, the inert organic solvent in step 1) is selected from at least one of toluene, xylene, o-xylene, m-xylene, n-butanol, butyl acetate, n-octane, and cyclohexanone, preferably toluene.

[0014] In one specific implementation, the mass ratio of the inert organic solvent to the by-product waste liquid from the norbornene process in step 1) is 10:1 to 10:10, preferably 10:5.

[0015] In one specific implementation, in step 1), ethylene is fed by a plunger pump, and the pressure reached when the ethylene is introduced into the reactor is 3-10 MPa, preferably 4-6 MPa.

[0016] In one specific implementation, the reaction temperature in step 1) is 200–250°C, preferably 220–240°C, and the reaction time is 6–24 h, preferably 8–12 h.

[0017] In one specific implementation, the distillation separation in step 2) adopts an atmospheric distillation process with 20-30 trays, atmospheric pressure or slightly negative pressure at the top of the column, and a top temperature of 90-96.5℃.

[0018] On the other hand, a method for producing norbornene includes the aforementioned method for recovering byproducts of the norbornene process.

[0019] In a preferred embodiment, the method for producing norbornene includes the following steps:

[0020] 1) Main reaction steps for the preparation of norbornene: dicyclopentadiene and ethylene are reacted in a reaction vessel to prepare norbornene;

[0021] 2) The reaction liquid in step 1) was subjected to two intermittent distillations to obtain the by-product waste liquid of the norbornene process;

[0022] 3) The norbornene by-product waste liquid generated in step 2) is recycled using the aforementioned method to prepare norbornene.

[0023] In one specific implementation, the reaction pressure of the main reaction in step 1) does not exceed 5 MPa, preferably 4 MPa; the reaction temperature is 200-250℃, preferably 210℃; and the reaction residence time is 4-12 h, preferably 8 h.

[0024] In one specific implementation, the mass ratio of the TCD / NB product obtained from the main reaction in step 1) is 0.16-0.66, preferably 0.55.

[0025] In one specific implementation, in the two batch distillations of step 2), the first distillation has 20-30 plates, the top pressure is atmospheric or slightly negative, and the top temperature is 90-96.5℃; the bottom of the distillation column is collected for a second distillation, with 20-30 plates, the top pressure is 0.8-1 kPa, and the top temperature is 88-94℃.

[0026] Compared with the prior art, the positive effects of the present invention are as follows:

[0027] This invention provides a method for recovering byproducts of the norbornene process. The byproduct waste liquid from the ethylene and norbornene processes is decomposed and added simultaneously at high temperature to prepare norbornene. Since the cracking and addition occur simultaneously in one reactor, endothermic and exothermic reactions are coupled. Compared with the traditional hydrocracking process, the reaction temperature is lower, the heat effect of the reaction is lower, and the process is safer.

[0028] The norbornene production method of this invention, due to the introduction of a by-product recovery process, requires a relatively low reaction pressure of only 5 MPa for the reaction of DCPD and ethylene to produce NB. As the ethylene pressure decreases, the selectivity of the by-product TCD increases. This process, supplementing the main NB and TCD process, results in a preparation process for norbornene and tetracyclododecene that offers advantages such as low reaction pressure, high production safety, good reaction selectivity, high overall NB product yield, and more stable production, facilitating industrial-scale production. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the reaction route for the recovery method of norbornene byproducts in this invention. Detailed Implementation

[0030] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0031] A method for recovering a byproduct of norbornene processing includes the following steps:

[0032] 1) Add inert organic solvent and nobornene process by-product waste liquid to a stainless steel reactor, then introduce ethylene into the reactor to reach a certain pressure and maintain it constant, keep the reaction temperature at 200-250℃, and the reaction time at 6-24h to obtain the reaction solution.

[0033] 2) The reaction solution from step 1) above is subjected to atmospheric distillation to obtain high-purity norbornene.

[0034] In the method of this invention, the by-product waste liquid from the norbornene process in step 1) is a by-product of the traditional liquid-phase method for preparing norbornene or tetracyclododecene, mainly including cyclopentadiene trimer, tetracyclododecene, and polymers formed by cyclopentadiene and norbornene. Figure 1 As shown, the by-product waste liquid from the norbornene process contains cyclic olefin polymers with at least one of the following structures: TCD, TM, TCN, RCN, and FCN. These polymers react with ethylene, undergoing both cracking and addition simultaneously to produce norbornene. Because cracking and addition occur concurrently in a single reactor, the endothermic and exothermic processes are coupled, allowing operation at relatively low reaction temperatures and ensuring high process safety.

[0035] The added inert organic solvent is selected from at least one of toluene, xylene, o-xylene, m-xylene, n-butanol, butyl acetate, n-octane, and cyclohexanone, preferably toluene. The mass ratio of the inert organic solvent to the by-product waste liquid from the norbornene process is 10:1 to 10:10, for example, including but not limited to 10:1.5, 10:2, 10:3, 10:4, 10:5, 10:6, 10:7, 10:8, and 10:9, preferably 10:5.

[0036] Ethylene is fed by a plunger pump and introduced into the reactor to achieve a pressure of 3-10 MPa. The amount of ethylene consumed is replenished in the same amount to keep the pressure constant. For example, including but not limited to 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, and 9 MPa, the preferred pressure is 4-6 MPa.

[0037] The reaction temperature in step 1) is 200–250°C, including but not limited to 200°C, 210°C, 220°C, 30°C, 240°C, and 250°C, preferably 220–240°C, and the reaction time is 6–24 h, including but not limited to 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, and 23 h, preferably 8–12 h.

[0038] In step 2), norbornene is separated using an atmospheric distillation process. The number of trays in the distillation column is 20-30, the pressure at the top of the column is atmospheric or slightly negative, and the temperature at the top of the column is 90-96.5℃.

[0039] On the other hand, a method for producing norbornene includes the following steps:

[0040] 1) Main reaction process for preparing norbornene: The main reaction process for preparing norbornene involves the addition of dicyclopentadiene and ethylene in a continuous reactor. This process can be referenced from existing technologies and is well known to those skilled in the art. For example, the reference is Zhou Qi's "Research on the Synthesis Process of Norbornene", DOI: CNKI:SUN:SYHA.0.2011-03-019. Specifically, for example, dicyclopentadiene and ethylene are continuously added to a continuous reactor at a reaction temperature of 210℃, an ethylene pressure of 4 MPa, a residence time of 8 h, and the molar ratio of ethylene to DCPD is always maintained at 2.4:1. The reaction solution enters the reaction vessel through an overflow pipe, and the system pressure is regulated by a back pressure valve on the reaction vessel.

[0041] 2) The reaction liquid in step 1) was subjected to two intermittent distillations to obtain the by-product waste liquid of the norbornene process.

[0042] 3) Add an inert organic solvent and the waste liquid from the norbornene process to the reactor, and then introduce ethylene into the reactor to reach a certain pressure. During this period, the consumed ethylene is continuously replenished to maintain a constant system pressure. After a period of reaction, the reaction solution is obtained.

[0043] 4) The reaction solution obtained in step 3) is separated into high-purity norbornene by distillation.

[0044] Since the by-product waste liquid from the norbornene process can be recovered using the recycling method of this invention to further obtain norbornene, the main reaction process for norbornene preparation in step 1) of the norbornene production method of this invention does not require a pressure as high as the existing technology's maximum of 20 MPa. The reaction can proceed at a pressure not exceeding 5 MPa. The produced by-products can be further recovered to produce norbornene, improving the overall NB product yield and reducing unit consumption. Simultaneously, due to the reduced main reaction pressure, the TCD / NB product ratio obtained from the main reaction increases, reaching 0.16-0.66.

[0045] In step 1) above, the reaction pressure of the main reaction shall not exceed 5 MPa, preferably 4 MPa; the reaction temperature shall be 200-250℃, preferably 210℃; and the reaction time shall be 4-12 h, preferably 8 h.

[0046] The by-product waste liquid in this invention is a heavy component obtained by further distillation of the reaction liquid from the traditional liquid-phase addition process for preparing norbornene or tetracyclododecene, after recovering the product and solvent. In the two batch distillations of step 2) above, the first distillation column has 20-30 plates, the top pressure is atmospheric or slightly negative, and the top temperature is 90-96.5℃; the bottom of the column is collected for a second distillation, with 20-30 plates, a top pressure of 0.8-1 kPa, and a top temperature of 88-94℃. The collected bottom of the column is the by-product waste liquid from the norbornene process.

[0047] The technical solution of the present invention will be further described below through examples, but this does not constitute any limitation.

[0048] Unless otherwise specified, all raw materials used in this invention are commercially available; and unless otherwise specified, all equipment is conventionally used in the field.

[0049] The by-product waste liquid in this invention is obtained from step 2) and Example 21, and has the following composition: TCD 24%, TM 6%, TCN 37%, RCN 22%, and FCN 2%.

[0050] The gas chromatography analysis method used in this invention was as follows: a Shimadzu Angilent 7820A gas chromatograph, a DB-5 capillary column (5% Phenyl Methyl Siloxan, 30m × 0.32mm × 0.25μm), and a flame ionization detector (FID). The injector and detector temperatures were both 290℃; the column temperature was initially set at 100℃ and held for 1 minute, then increased to 250℃ at a rate of 15℃ / min and held for 5 minutes. The column pressure was 8.59 psi, and the flow rate was 1.5 mL / min. The injection volume was 0.2 μL. Quantification was performed using the area normalization method.

[0051] Example 1

[0052] 1) Add the inert organic solvent and norbornene by-product waste liquid with the mass ratio listed in Table 1 to a 2L reactor. After nitrogen purging, heat to 200-250℃ and continuously replenish the consumed ethylene at an ethylene pressure of 3-10 MPa using a horizontal flow pump for 6-24 hours. Then cool down and depressurize to obtain a high-yield reaction solution.

[0053] After cooling and depressurization, samples were taken for gas chromatography analysis, and the results are shown in Table 1. The collected reaction solution was then distilled in a 25-plate distillation column, and the fraction at the top of the column at 96.5℃ was collected. Analysis showed that the purity of norbornene was 99.9%.

[0054] Other embodiments are the same as in Embodiment 1, except for the reaction conditions, and the results are shown in Table 1.

[0055] Table 1. Specific reaction conditions and results for Examples 1-9

[0056] Example Solvent types Solvent to norbornene by-product mass ratio Temperature / °C Pressure / °C Reaction time / h NB selectivity / % 1 Toluene 10:1 200 10 18 32 2 xylene 10:3 250 5 6 55 3 n-Butanol 10:5 230 3 24 92 4 Butyl acetate 10:2 220 7 12 73 5 n-Octane 10:4 240 8 8 95 6 Cyclohexanone 10:2 210 6 10 42 7 o-xylene 10:4 220 4 9 58 8 m-xylene 10:5 230 8 20 89 9 Toluene 10:3 240 9 15 92

[0057] 2) Add 600g of norbornene to the bottom of a 2L continuous reactor, purge with nitrogen, and raise the temperature to 200-250℃. Add ethylene to bring the pressure to 2-5 MPa, and adjust the system pressure to 2-5 MPa using the back pressure valve on the reactor. Then, continuously add dicyclopentadiene and ethylene using a horizontal flow pump and a plunger pump, respectively, controlling the residence time to 4-12 hours. Maintain the ethylene to DCPD molar ratio at 2.4:1 throughout. The reaction solution flows into the reactor via the overflow pipe.

[0058] The reaction conditions and chromatographic analysis of the samples are shown in Table 2.

[0059] Table 2 Specific reaction conditions and results of Examples 10-20

[0060]

[0061]

[0062] Comparative Example 1

[0063] The ethylene pressure was 20 MPa, and other conditions were the same as in Example 11. Samples were taken for gas chromatography analysis. The results showed that the conversion rate was 99%, the TCD / NB mass ratio was 0.04, which was much lower than the method of the present invention, and the selectivity of other by-products was 1.5%.

[0064] Example 21

[0065] The reaction solution obtained in Example 11 was transferred into a distillation system with 25 trays. The pressure at the top of the column was atmospheric pressure, and NB was collected at a top temperature of 96.5°C, yielding NB with a purity of 99.9%. After distillation, the bottom of the column was transferred to a second distillation column with 25 trays. TCD was collected at a top pressure of 1 kPa and a top temperature of 94°C, yielding TCD with a purity of 99%. The remaining bottom of the column was waste liquid from the norbornene process, with a composition of 24% TCD, 6% TM, 37% TCN, 22% RCN, and 2% FCN.

[0066] The waste liquid was converted using the method in Example 5, with a TCD conversion rate of 20%, a TM conversion rate of 98%, a TCN conversion rate of 97%, an RCN conversion rate of 89%, and an FCN conversion rate of 92%. The final NB selectivity was 95%, and the NB purity after distillation was 99.9%.

[0067] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for producing norbornene, characterized in that, Includes the following steps: 1) Main reaction process for the preparation of norbornene: Dicyclopentadiene and ethylene are added in a reaction vessel to prepare norbornene. The reaction pressure of the main reaction does not exceed 5 MPa. 2) The reaction liquid from step 1) was subjected to two intermittent distillations to obtain the by-product waste liquid from the norbornene process; 3) Add an inert organic solvent and the waste liquid from the norbornene process to the reactor, then introduce ethylene into the reactor to reach a pressure of 3-10 MPa and maintain it constant. After reacting at 200-250℃ for 6-24 hours, the reaction solution is obtained. 4) The reaction solution obtained in step 3) is separated into high-purity norbornene by distillation; The by-product waste liquid from the norbornene process is a heavy component by-product of the liquid-phase preparation of norbornene, including cyclic olefin polymers with at least one structure of formula 1 to formula 5: 。 2. The production method according to claim 1, characterized in that, In step 3), the inert organic solvent is selected from at least one of toluene, xylene, o-xylene, m-xylene, n-butanol, butyl acetate, n-octane, and cyclohexanone.

3. The production method according to claim 2, characterized in that, In step 3), the inert organic solvent is toluene.

4. The production method according to any one of claims 1-3, characterized in that, In step 3), the mass ratio of the inert organic solvent to the by-product waste liquid from the norbornene process is 10:1 to 10:

10.

5. The production method according to claim 4, characterized in that, In step 3), the mass ratio of the inert organic solvent to the by-product waste liquid from the norbornene process is 10:

5.

6. The production method according to any one of claims 1-3, characterized in that, In step 3), ethylene is fed using a plunger pump, and the pressure reached when ethylene is introduced into the reactor is 4-6 MPa.

7. The production method according to any one of claims 1-3, characterized in that, The reaction temperature in step 3) is 220–240°C, and the reaction time is 8–12 h.

8. The production method according to any one of claims 1-3, characterized in that, In step 4), the distillation separation adopts an atmospheric distillation process with 20-30 trays, atmospheric pressure or slightly negative pressure at the top of the column, and a temperature of 90-96.5℃ at the top of the column.

9. The method for producing norbornene according to claim 1, characterized in that, The reaction temperature of the main reaction in step 1) is 200-250℃; the reaction time is 4-12h.

10. The method for producing norbornene according to claim 9, characterized in that, The reaction pressure of the main reaction in step 1) is 4 MPa; the reaction temperature is 210℃; and the reaction time is 8 h.

11. The method for producing norbornene according to claim 1, characterized in that, The mass ratio of TCD / NB products obtained from the main reaction in step 1) is 0.16-0.

66.

12. The method for producing norbornene according to claim 11, characterized in that, The mass ratio of the TCD / NB product obtained from the main reaction in step 1) is 0.

55.

13. The method for producing norbornene according to claim 11, characterized in that, In the two intermittent distillations in step 2), the first distillation has 20-30 plates, the top pressure is atmospheric or slightly negative, and the top temperature is 90-96.5℃. The bottom of the column is collected for a second distillation, with 20-30 plates, a top pressure of 0.8-1 kPa, and a top temperature of 88-94℃. The bottom of the column is obtained as the waste liquid from the norbornene process.

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