Method and system for separating and purifying polymer-grade norbornene with high yield

Abstract

The invention relates to the technical field of separation and purification, and discloses a method and a system for separating and purifying polymer-grade norbornene with high yield. The method provided by the invention is suitable for separation and purification of the norbornene synthesis liquid obtained by a solvent synthesis method, and has the characteristics of easiness in industrial popularization, low energy consumption, high yield, high purity of the obtained norbornene product and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of separation and purification, and in particular to a method and system for separating and purifying polymerization-grade norbornene with high yield. Background Art

[0002] Norbornene is an important comonomer, usually prepared by Diels-Alder cycloaddition reaction of cyclopentadiene and ethylene under high temperature and high pressure conditions, and can be prepared by non-ring-opening polymerization with α-olefins such as ethylene, propylene, and styrene under the action of Ziegler-Natta catalysts or metallocene catalysts to prepare cycloolefin copolymers (COC). COC has good heat resistance, chemical stability, extremely high transparency, dimensional stability, melt fluidity, moisture barrier properties and extremely low dielectric constant, and is widely used in the manufacture of contact lenses, car headlights, optical lenses, prisms, optical films for LCDs, food packaging electronic and electrical components, etc.

[0003] The norbornene monomer used to synthesize COC needs to meet higher purity requirements. However, due to the complex composition of the norbornene synthesis liquid, which contains unreacted raw materials, new components produced by the reaction, impurities introduced by the raw materials and their products, and impurities produced by side reactions, its separation and purification requires not only consideration of the composition characteristics of the norbornene synthesis liquid, but also consideration of the reactions that may occur during the separation process and the impact of the impurities produced by these reactions on the separation process and the purity of the final product.

[0004] At present, the research on norbornene mainly focuses on the synthesis method, and there is little research on how to separate and obtain high-purity norbornene in the future, especially there is almost no report on the norbornene purification process that can be applied industrially. Although CN1284051A discloses a method for separating and obtaining norbornene from norbornene synthesis liquid, the dicyclopentadiene raw material used contains some light impurities such as butadiene, isoprene and methylcyclopentadiene and heavy impurities such as methyltetrahydroindene, and the norbornene synthesis reaction also generates some medium and heavy impurities, which is quite different from the actual industrial norbornene synthesis liquid. Moreover, it is aimed at the separation and purification of norbornene synthesis liquid obtained by solvent-free synthesis method, and it is of limited help to obtain a method for separating and obtaining high-purity norbornene from norbornene synthesis liquid obtained by solvent synthesis method. Moreover, CN1284051A also teaches that the topping tower C2 is operated at normal pressure, the tower bottom temperature is 95-100°C, and the tower top temperature is 94-100°C. According to the process parameters, most of the tower top stream is required to be norbornene, so a part of the norbornene must be lost at the tower top, but the tower bottom temperature often exceeds 100°C at normal pressure; it also teaches that the second tailing tower C3 is operated at normal pressure, the tower bottom temperature is 95-100°C, and the tower top temperature is 95-100°C. If the tower bottom temperature does not exceed 100°C, the tower bottom stream needs to contain a large amount of norbornene, which is 97.85% in Example 1, resulting in norbornene loss. The norbornene product obtained at the tower top contains 3ppm cyclopentadiene. It can be seen that the norbornene loss in the method of this patent is relatively large, and the cyclopentadiene content in the obtained product is also not ideal. In addition, considering that the solvent synthesis method is the mainstream method for producing norbornene at present, it is very important to develop a method that is easy to industrialize and energy-saving and environmentally friendly to separate the norbornene synthesis liquid obtained by the solvent synthesis method to obtain a high-purity norbornene product for norbornene production and related downstream industries. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of low norbornene yield and high impurity content in the product in the prior art, and to provide a method and system for separating and purifying polymerization-grade norbornene with high yield. The method separates and purifies norbornene synthesis liquid obtained by a synthesis method with a solvent, and has the advantages of reliable process, easy control, mild conditions, low energy consumption, high yield, and high purity of norbornene product.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for separating and purifying polymerization-grade norbornene with high yield, the method comprising:

[0007] (1) Pre-deweight removal: The norbornene synthesis liquid generated by the reaction of a toluene solution of dicyclopentadiene with ethylene is introduced into a pre-deweight removal tower for first distillation to obtain a pre-deweight removal tower bottom stream and a pre-deweight removal tower top stream.

[0008] wherein the conditions of the first distillation are such that the toluene content in the pre-deweighting tower overhead stream is 1-25 wt %;

[0009] (2) Light removal: the pre-heavy removal tower top stream obtained in step (1) is introduced into a light removal tower for secondary distillation to obtain a light removal tower bottom stream and a light removal tower top stream.

[0010] The second distillation condition is such that the bottom temperature of the light removal tower does not exceed 120°C;

[0011] (3) Norbornene refining: introducing the light-removal tower bottom stream obtained in step (2) into a refining tower for third distillation to obtain a refining tower bottom stream and a refining tower top stream,

[0012] The conditions of the third distillation are such that the bottom temperature of the refining tower does not exceed 110°C.

[0013] A second aspect of the present invention provides a system for separating and purifying norbornene from a norbornene synthesis liquid, the system comprising a pre-heavy removal tower, a light removal tower and a refining tower;

[0014] The material inlet and outlet of the pre-deweighting tower include: the inlet of the material to be pre-deweighting, the outlet of the pre-deweighting tower bottom logistics and the outlet of the pre-deweighting tower top logistics;

[0015] The material inlet and outlet of the light-removal tower include: the inlet of the material to be removed, the outlet of the bottom logistics of the light-removal tower and the outlet of the top logistics of the light-removal tower;

[0016] The material inlets and outlets of the refining tower include: an inlet for materials to be refined, a refining tower bottom logistics outlet, and a refining tower top logistics outlet;

[0017] Among them, the pre-deheavy tower top logistics outlet of the pre-deheavy tower is connected to the light material inlet to be de-lightened of the light-removing tower, and the light-removing tower bottom logistics outlet of the light-removing tower is connected to the light material inlet to be refined of the refining tower.

[0018] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0019] (1) The method provided by the present invention reduces the content of norbornene in the bottom flow of the pre-deweighting tower by removing the solvent toluene and part of the heavy components in the norbornene synthesis liquid during the pre-deweighting process, thereby increasing the overall content of norbornene. At the same time, such a treatment method can also effectively reduce energy consumption and reflux ratio, thereby shortening the residence time of the norbornene synthesis liquid in the pre-deweighting tower, thereby reducing the occurrence of depolymerization reaction and addition reaction, and avoiding the problem of low removal rate and removal efficiency caused by the mutual conversion of light and heavy components during the separation and purification process.

[0020] (2) The method provided by the present invention can obtain a high-purity norbornene product by adopting a specific step combination and a specific condition control method, which meets the needs of subsequent industrial applications. In addition, the method provided by the present invention is simple and easy to implement, the conditions are relatively mild, and it is easy to promote industrialization.

[0021] (3) The main component of the refining tower bottom stream obtained in the method provided by the present invention is toluene, and it also includes a small amount of recyclable components such as norbornene and dicyclopentadiene. Therefore, in the preferred embodiment of the present invention, by recycling the stream, it is possible to further reduce resource waste and improve the overall yield of norbornene. Moreover, since the heavy components contained therein are very few, even if it is recycled, it will not have a significant impact on the coking of the equipment and will not affect the overall production efficiency. At the same time, by recycling the materials, the condition control requirements of the refining tower are reduced, and it can also play a role in reducing energy consumption and reducing management difficulty, making the method easier to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the system for separating and purifying norbornene used in Example 1.

[0023] Description of Reference Numerals

[0024] T-1: pre-deweight removal tower; T-2: lightness removal tower; T-3: refining tower; T-4: deweight removal tower;

[0025] S-1: norbornene synthesis liquid; S-2: pre-deheavy-stripping tower top logistics; S-3: pre-deheavy-stripping tower bottom logistics; S-4: deheavy-stripping tower top logistics; S-5: deheavy-stripping tower bottom logistics; S-6: refining tower top logistics (norbornene product); S-7: refining tower bottom logistics; S-8: deheavy-stripping tower top logistics; S-9: deheavy-stripping tower bottom logistics. DETAILED DESCRIPTION

[0026] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] In the present invention, unless otherwise specified, "heavy components" refer to components in the norbornene synthesis liquid having a boiling point greater than that of norbornene, including solvents (mainly toluene) and intermediate products (such as dicyclopentadiene, tricyclopentadiene, tetracyclododecene, etc.); "light components" refer to components in the norbornene synthesis liquid having a boiling point less than that of norbornene, mainly including raw materials remaining in the norbornene synthesis liquid, and impurities (such as cyclopentadiene, isoprene, isoprene, etc.) generated by the conversion of the raw materials or entrained in the raw materials; "polymerization grade norbornene" refers to norbornene with high purity and low impurity content, so as to meet the production requirements of COC with norbornene as one of the main raw materials (purity ≥ 98% by weight, and the contents of cyclopentadiene and dicyclopentadiene are both less than 10 ppm, preferably less than 5 ppm, for example, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, or any intermediate value between any two of the above values).

[0028] In the present invention, unless otherwise specified, the theoretical plate number is obtained by experiments using a general determination method in the separation field.

[0029] In the present invention, unless otherwise specified, the operation numbers (such as "first", "second", etc. in the first distillation and the second distillation) are only used to make it easier to distinguish the same treatment in different steps in the description, and have no limiting effect on the specific operation method, conditions and sequence.

[0030] In the present invention, unless otherwise specified, "ppm" means one part per million by mass, and 100 ppm = 0.01% by weight.

[0031] When norbornene is synthesized in a solvent-containing manner, the obtained norbornene synthesis liquid contains, in addition to norbornene and a solvent (usually toluene), unreacted raw material cyclopentadiene and heavy components with a boiling point higher than that of norbornene, such as dicyclopentadiene, tetracyclododecene, tricyclopentadiene, etc. From the perspective of separation and purification, it is best to separate and remove the heavy components at one time. However, since cyclopentadiene and dicyclopentadiene can be mutually converted under certain conditions during the separation process, the distillation process is actually a reactive distillation process, and the boiling point of cyclopentadiene is lower than that of norbornene, and the boiling point of dicyclopentadiene is higher than that of norbornene, it is difficult to completely remove the heavy components therein at one time when purifying and separating the norbornene synthesis liquid, which easily leads to the problem that the purity of the norbornene product is insufficient and cannot meet the production needs.

[0032] The inventors of the present invention cleverly discovered during the research process that a method of first removing most of the heavy components in the norbornene synthesis liquid (i.e., "pre-heavy removal"), then removing the light components, and finally removing the heavy components is adopted, and the amount of the heavy components removed during the pre-heavy removal process is controlled, leaving a portion of heavy components such as solvents in the pre-heavy removal tower top stream, while controlling the distillation temperature of the light component removal and the final heavy component removal process, allowing cyclopentadiene in the material to undergo dimerization reaction in the light removal tower to generate dicyclopentadiene, which can avoid or minimize the depolymerization reaction of dicyclopentadiene to generate cyclopentadiene, thereby greatly reducing the cyclopentadiene content in the stream extracted from the bottom of the light removal tower, and avoiding the adverse effect of bringing cyclopentadiene into the refining tower and finally appearing in the norbornene product on the purity of the product. Compared with the method of removing the heavy components in the norbornene synthesis liquid at one time, the method of the present invention can greatly reduce the concentration of the heavy components in the bottom material of the refining tower, reduce the bottom temperature, and prevent the depolymerization of dicyclopentadiene. Not only can a high-purity norbornene product be obtained with a higher yield, but the energy consumption in the separation and purification process is also effectively reduced, making it more suitable for industrial production applications.

[0033] Based on the above findings, the first aspect of the present invention provides a method for separating and purifying polymerization-grade norbornene with high yield, the method comprising:

[0034] (1) Pre-deweight removal: The norbornene synthesis liquid generated by the reaction of a toluene solution of dicyclopentadiene with ethylene is introduced into a pre-deweight removal tower for first distillation to obtain a pre-deweight removal tower bottom stream and a pre-deweight removal tower top stream.

[0035] wherein the conditions of the first distillation are such that the toluene content in the pre-deweighting tower overhead stream is 1-25 wt %;

[0036] (2) Light removal: the pre-heavy removal tower top stream obtained in step (1) is introduced into a light removal tower for secondary distillation to obtain a light removal tower bottom stream and a light removal tower top stream.

[0037] The second distillation condition is such that the bottom temperature of the light removal tower does not exceed 120°C;

[0038] (3) Norbornene refining: introducing the light-removal tower bottom stream obtained in step (2) into a refining tower for third distillation to obtain a refining tower bottom stream and a refining tower top stream,

[0039] The conditions of the third distillation are such that the bottom temperature of the refining tower does not exceed 110°C.

[0040] The method provided by the present invention can separate and purify the norbornene synthesis liquid obtained by any prior art process of synthesizing norbornene in a solvent-free manner. Generally, the norbornene synthesis liquid contains norbornene and toluene (i.e., the solvent used in the synthesis process), and at least one of cyclopentadiene, dicyclopentadiene, tricyclopentadiene, tetracyclododecene, pentene, pentadiene, 3-methylcyclohexene, santalen, methylnorbornene, etc. Preferably, the norbornene synthesis liquid includes cyclopentadiene, norbornene, toluene, dicyclopentadiene, tricyclopentadiene, tetracyclododecene and santalen.

[0041] In the present invention, the purpose of the pre-deweighting step (1) is to remove some of the heavy components in the norbornene synthesis liquid. By controlling the toluene content in the pre-deweighting tower top stream, the following effects are achieved: first, most of the toluene is extracted at the bottom of the tower, effectively controlling the pre-deweighting tower bottom temperature; second, the inventors have found in long-term research that when the toluene content in the pre-deweighting tower top stream reaches a specific level, the impurity content in the norbornene product, especially the heavy component impurity content other than the solvent, can be effectively reduced, so that the norbornene purity can reach the required level; third, the subsequent refining tower bottom temperature is controlled to prevent high temperature from producing heavier components and adversely affecting the quality of the norbornene product, while effectively improving the norbornene yield in the separation and purification process and reducing separation energy consumption. In addition, the pre-deweighting tower bottom stream can be further processed later, so that the solvent and intermediate products therein are recovered and recycled for use in the norbornene synthesis process, further improving the overall yield of norbornene while reducing resource waste, so that the production process is more in line with the needs of green and sustainable development.

[0042] To achieve the above object, according to a preferred embodiment of the present invention, in step (1), the conditions of the first distillation are such that the toluene content in the pre-weight-removal tower overhead stream is 3-15% by weight, more preferably 3-10% by weight, for example 3%, 4%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, 10% by weight, or any intermediate value between any two of the above values.

[0043] In order to further improve the yield of norbornene products and avoid excessive loss of norbornene, the content of norbornene in the pre-deweight removal tower bottom stream should also be considered when controlling the conditions of the first distillation in step (1). Preferably, the conditions of the first distillation are such that the content of norbornene in the pre-deweight removal tower bottom stream does not exceed 3% by weight, preferably does not exceed 2% by weight, and more preferably does not exceed 1% by weight.

[0044] In order to make the material component content in the pre-deweight removal tower top stream and the pre-deweight removal tower bottom stream reach the above-mentioned level, according to some preferred embodiments of the present invention, the number of theoretical plates of the pre-deweight removal tower is 20-55.

[0045] Preferably, the conditions of the first distillation include: a tower top pressure of 50-200 kPa, and a tower top temperature of 50-115°C.

[0046] Since heavy components such as dicyclopentadiene and tetracyclododecene undergo depolymerization reaction at a relatively high temperature, dicyclopentadiene depolymerizes into cyclopentadiene, and tetracyclododecene depolymerizes into cyclopentadiene and norbornene, and cyclopentadiene undergoes Diels-alder diene synthesis reaction with substances containing carbon-carbon double bonds in the heavy components to generate heavier components, which easily cause equipment coking and blockage. Therefore, in order to reduce the occurrence of equipment coking and blockage problems and improve production efficiency, the pre-deweighting tower is preferably operated under reduced pressure, normal pressure or slightly pressurized conditions, and more preferably operated under normal pressure or reduced pressure conditions.

[0047] According to a preferred embodiment of the present invention, the conditions of the first distillation include: a tower top pressure of 50-120 kPa, and a tower top temperature of 60-110° C. More preferably, the tower top pressure is 50-100 kPa (for example, it can be 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, or any intermediate value between any of the above two values), and the tower top temperature is 70-100° C. (for example, it can be 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., or any intermediate value between any of the above two values).

[0048] Preferably, the conditions of the first distillation further include: a tower bottom temperature of 85-130°C. Preferably, the tower bottom temperature does not exceed 120°C. For example, the tower bottom temperature of the first distillation can be 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any intermediate value between any of the above two values. Usually, the tower bottom temperature of the first distillation is higher than the tower top temperature.

[0049] According to the theoretical plate number of the deweighting tower used in the subsequent solvent recovery process and the composition of the synthetic liquid used, more preferably, the reflux ratio of the first distillation is 1-10, preferably 2-6.

[0050] In order to reduce the norbornene content in the bottom extraction stream, according to a preferred embodiment of the present invention, the norbornene synthesis liquid is fed into the upper part of the pre-deweighting tower. That is, the feed port position can be set at a position above 1 / 2 of the packing or tray from the upper end, preferably above 1 / 3.

[0051] According to a preferred embodiment of the present invention, the pre-deheavy-removal tower top stream obtained in step (1) contains light components such as cyclopentadiene, norbornene, and a (small) portion of toluene and heavy components.

[0052] According to a preferred embodiment of the present invention, the pre-deweighting tower bottom stream obtained in step (1) contains: a small amount of norbornene and a (majority) portion of toluene and heavy components.

[0053] In the present invention, the purpose of light removal in step (2) is to remove light components in the pre-heavy removal tower top stream, obtain a mixture of norbornene, toluene and heavy components, and obtain a high-purity norbornene product through further refining treatment. The light components contained in the norbornene synthesis liquid mainly include unreacted cyclopentadiene and components with lower boiling points brought in by the dicyclopentadiene raw material, and may also be components produced by reactions of some components in the dicyclopentadiene raw material, such as polymers of isoprene and cyclopentadiene, polymers of isoprene and cyclopentadiene, etc. These polymers will also depolymerize to produce isoprene or isoprene during the process of dicyclopentadiene depolymerization to cyclopentadiene. The specific composition of the light components in the norbornene synthesis liquid is closely related to the composition of the dicyclopentadiene raw material. In step (2), the light components should be removed as much as possible, so that the content of light component impurities in the norbornene product obtained by purification using the method of the present invention meets the COC production requirements.

[0054] According to a preferred embodiment of the present invention, in step (2), the conditions of the second distillation are such that the content of light components in the light removal tower bottom stream (i.e., the total content of components having a boiling point lower than that of norbornene) does not exceed 20 ppm, preferably does not exceed 10 ppm, and more preferably does not exceed 2 ppm.

[0055] Preferably, in step (2), the conditions of the second distillation are such that the content of cyclopentadiene in the light-removal tower bottom stream does not exceed 10 ppm, preferably does not exceed 5 ppm, and more preferably does not exceed 1 ppm.

[0056] In order to make the content of components contained in the bottom stream of the light-removal tower meet the above requirements, according to a preferred embodiment of the present invention, the number of theoretical plates of the light-removal tower is 30-70.

[0057] Preferably, the conditions of the second distillation include: a tower top pressure of 40-120 kPa, and a tower top temperature of 50-100°C.

[0058] In the method provided by the present invention, the lightness removal tower can be operated under reduced pressure, normal pressure or slightly increased pressure.

[0059] Preferably, the conditions of the second distillation include: a top pressure of 40-110 kPa (for example, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, or any intermediate value between the above two values), and a top temperature of 45-90°C (for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any intermediate value between the above two values). It is preferred to carry out the second distillation under reduced pressure conditions, and the conditions may include, for example, a top pressure of 40-90 kPa (for example, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, or any intermediate value between the above two values), a top temperature of 45-80°C (for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any intermediate value between the above two values).

[0060] In order to minimize the reaction of the bottom material, the bottom temperature should not be too high during the second distillation. Preferably, the conditions of the second distillation also include: a bottom temperature of 80-110°C, preferably a bottom temperature not exceeding 105°C. For example, the bottom temperature of the second distillation can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, or any intermediate value between the above two values. Usually, the bottom temperature of the second distillation is higher than the top temperature.

[0061] In order to further reduce the content of light components in the light removal tower bottom stream and improve the purity of the norbornene product, more preferably, the reflux ratio of the second distillation is 8-40, preferably 20-40.

[0062] In order to reduce the cyclopentadiene content in the bottom stream, according to a preferred embodiment of the present invention, the pre-heavy-removal tower top stream can be fed into the upper part of the light-removal tower. That is, the feed port position can be set above the 1 / 2 position of the packing or the tray, preferably above the 1 / 3 position.

[0063] According to a preferred embodiment of the present invention, the light components such as cyclopentadiene, pentene, and pentadiene are contained in the light-removal tower top stream obtained in step (2).

[0064] According to a preferred embodiment of the present invention, the light-removal tower bottom stream obtained in step (2) contains: (mainly) norbornene and (a small amount of) toluene and heavy components.

[0065] In the present invention, the purpose of the step (3) of refining norbornene is to remove toluene and heavy components in the bottom stream of the light removal tower, so that the content of solvent and heavy component impurities in the norbornene product reaches the desired level.

[0066] According to a preferred embodiment of the present invention, in step (3), the conditions of the third distillation are such that the content of dicyclopentadiene and / or tetracyclododecene in the refining tower top stream does not exceed 10 ppm, preferably does not exceed 5 ppm, and more preferably does not exceed 1 ppm. Considering that solvent is also used when norbornene is used for polymerization to produce cycloolefin copolymers, there is no need to make too many requirements on the solvent content in the refining tower bottom stream.

[0067] In order to make the (heavy component) impurity content in the refining tower top stream reach the above level, according to a preferred embodiment of the present invention, the number of theoretical plates of the refining tower is 15-60.

[0068] The light component content in the light removal tower bottom stream is extremely low, but some of the heavy components contained therein can be converted into light components through depolymerization reaction, resulting in an increase in the light component impurity content in the refining tower top stream, affecting the purity of the norbornene product. In order to avoid depolymerization reaction in the refining tower, which causes some of the heavy components in the introduced light removal tower bottom stream to be converted into light component impurities, the top and bottom temperatures in the refining tower should not be too high.

[0069] Preferably, the third distillation is operated under reduced pressure. Preferably, the conditions of the third distillation include: the tower top pressure is 20-80kPa (for example, it can be 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, or any intermediate value between the above two values), and the tower top temperature is 45-90°C (for example, it can be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any intermediate value between the above two values). Preferably, the tower top pressure is 40-70kPa and the tower top temperature is 50-80°C.

[0070] Preferably, the conditions of the third distillation further include: a tower bottom temperature of 65-110° C., preferably a tower bottom temperature of 75-95° C. For example, the tower bottom temperature of the third distillation can be 75° C., 80° C., 85° C., 90° C., 95° C., or any intermediate value between the above two values. Usually, the tower bottom temperature of the third distillation is higher than the tower top temperature.

[0071] Considering the difficulty of separation, more preferably, the reflux ratio of the third distillation is 2-12, and preferably the reflux ratio of the third distillation is 3-7.

[0072] In order to reduce the content of heavy component impurities in the refining tower top stream and obtain qualified norbornene products, according to a preferred embodiment of the present invention, the light removal tower bottom stream can be fed in the lower part of the refining tower. That is, the feed port position can be set below the 1 / 2 position of the packing or tray from the top of the tower, preferably below the 2 / 3 position.

[0073] According to a preferred embodiment of the present invention, the refined tower top stream obtained in step (3) mainly contains norbornene, and its purity is relatively high, which can meet the requirements for preparing COC, and can be directly packaged and used as a high-purity norbornene product. The main impurity in the refined tower top stream is toluene. According to actual production needs, in order to further reduce the impurity content in the refined tower top stream, step (3) may further include the operation of removing toluene from the refined tower top stream, or the conditions of the third distillation may be adjusted to further reduce the toluene content in the refined tower top stream.

[0074] According to a preferred embodiment of the present invention, the refined bottom stream obtained in step (3) contains: (a small amount of) norbornene, toluene and heavy components.

[0075] Considering that the solvent toluene and some heavy components (such as dicyclopentadiene, tetracyclododecene, etc.) contained in the refining tower bottom stream are raw materials or intermediates in the synthesis process of norbornene, in order to further improve the overall yield of norbornene and reduce resource waste, the toluene and some heavy components in the refining tower bottom stream can be separated and recovered.

[0076] For the above purpose, according to a preferred embodiment of the present invention, the method further comprises:

[0077] (4) Solvent recovery: The pre-deweighting tower bottom stream obtained in step (1) is introduced into a deweighting tower for fourth distillation to obtain a deweighting tower bottom stream and a deweighting tower top stream, and the deweighting tower top stream is recycled as a recovery solvent.

[0078] In the present invention, the purpose of step (4) solvent recovery is to recycle the solvent in the pre-weight-removing tower bottom stream, so that the whole process can be industrialized and reach the level of green chemical industry, and improve economic benefits. Toluene can be reused to dissolve dicyclopentadiene in the norbornene production process after recovery. Therefore, the recovery solvent obtained in step (4) can also contain dicyclopentadiene in addition to toluene. Moreover, since cyclopentadiene is one of the raw materials for norbornene synthesis, it is also allowed to depolymerize dicyclopentadiene to generate cyclopentadiene even in the fourth distillation process. However, the recovery solvent should be avoided as much as possible to include tetracyclododecene and heavier components, so as not to increase the coking of norbornene synthesis equipment, affecting production efficiency and product quality. Therefore, in general, the condition control of the fourth distillation can be relatively loose, without too strict control.

[0079] Based on the above principles, according to a preferred embodiment of the present invention, in step (4), the number of theoretical plates of the deweighting tower is 5-25.

[0080] According to a preferred embodiment of the present invention, the conditions of the fourth distillation are such that the content of tetracyclododecene in the weight removal tower top stream does not exceed 1 wt%.

[0081] In order to improve the utilization rate of dicyclopentadiene, preferably, the conditions of the fourth distillation are such that the content of dicyclopentadiene in the deheavy tower bottom stream does not exceed 2 wt%.

[0082] According to some preferred embodiments of the present invention, the conditions of the fourth distillation include: the tower top pressure is 20-80kPa (for example, it can be 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, or any intermediate value between the above two values), and the tower top temperature is 55-120°C (for example, it can be 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any intermediate value between the above two values). Preferably, the tower top pressure is 40-70kPa and the tower top temperature is 70-100°C.

[0083] Preferably, the conditions of the fourth distillation further include: a tower bottom temperature of 150-250° C., preferably 180-220° C. For example, the tower bottom temperature of the fourth distillation can be 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., or any intermediate value between any of the above two values. Usually, the tower bottom temperature of the fourth distillation is higher than the tower top temperature.

[0084] More preferably, the reflux ratio of the fourth distillation is 0.2-3, preferably 0.3-1.

[0085] In order to reduce the extraction amount of solvent toluene at the bottom of the tower and reduce the content of tetracyclododecene in the tower top stream, according to a preferred embodiment of the present invention, the pre-deweighting tower bottom stream can be fed in the middle of the deweighting tower, that is, the feed port position can be set in the middle of the packing or the tower plate.

[0086] According to a preferred embodiment of the present invention, the deweighting tower top stream obtained in step (4) mainly contains toluene. In addition to toluene, it may also contain (a small amount of) norbornene, dicyclopentadiene, and (a small amount of) components with a boiling point lower than dicyclopentadiene (such as cyclopentadiene, etc.).

[0087] According to a preferred embodiment of the present invention, the deheavy tower bottom stream obtained in step (4) contains heavy components having a boiling point higher than toluene, such as tetracyclododecene.

[0088] Considering that tetracyclododecene, dicyclopentadiene, etc. are also important raw materials for cycloolefin copolymers, therefore, in order to further improve the economic benefits of the process of the present invention, according to some preferred embodiments of the present invention, the method provided by the present invention further includes:

[0089] (5) Recovery of intermediate products: Separate and recover tetracyclododecene and / or dicyclopentadiene in the deweighting tower bottom stream obtained in step (4). Any method that can be used for the above-mentioned component separation in the art can be applied to the present invention, and preferably the separation method is selected from distillation and / or depolymerization reaction distillation.

[0090] The inventors of the present invention have cleverly discovered in long-term research that when the method provided by the present invention is used to separate and purify norbornene, if a part of the overhead stream of the light-removing tower obtained in step (2) is introduced into the pre-heavy-removing tower, the cyclopentadiene contained in the material is allowed to flow in the equipment such as pipelines, storage tanks, pre-heavy-removing towers, and light-removing towers for a residence time and self-dimerize to generate dicyclopentadiene (the optimal self-dimerization temperature is 80-95° C.), on the one hand, the loss of dicyclopentadiene / cyclopentadiene can be reduced, and on the other hand, cyclopentadiene can be dimerized to dicyclopentadiene in the circulation process (pre-heavy-removing tower, light-removing tower, storage tank, etc.), and at the same time, the distillation temperature of the refining tower is controlled by a reduced pressure operation to avoid the depolymerization reaction of dicyclopentadiene in the refining tower to generate cyclopentadiene, which can greatly improve the yield of norbornene. Another part of the overhead stream of the light-removing tower is extracted to avoid the accumulation of some light components such as pentene and pentadiene in the system.

[0091] In addition, since most of the components in the refined tower bottom stream obtained in step (3) are toluene, dicyclopentadiene, tetracyclododecene, etc., which can be reused as solvents, raw materials, and intermediate raw materials in the norbornene production process, these components can be recycled in order to further improve the utilization rate of the raw materials.

[0092] Based on the above findings, according to some preferred embodiments of the present invention, the method provided by the present invention further comprises:

[0093] (6) Material circulation: 0-75 wt % of the de-lightening tower top stream obtained in step (2) is introduced into the pre-de-lightening tower, and / or, the refining tower bottom stream obtained in step (3) is introduced into the pre-de-lightening tower.

[0094] According to a particularly preferred embodiment of the present invention, the method comprises:

[0095] (1) Pre-deweight removal: The norbornene synthesis liquid generated by the reaction of a toluene solution of dicyclopentadiene with ethylene is introduced into a pre-deweight removal tower for first distillation to obtain a pre-deweight removal tower bottom stream and a pre-deweight removal tower top stream.

[0096] The conditions of the first distillation are such that the toluene content in the pre-deweighting tower overhead stream is 5-20 wt %;

[0097] (2) Light removal: the pre-heavy removal tower top stream obtained in step (1) is introduced into a light removal tower for secondary distillation to obtain a light removal tower bottom stream and a light removal tower top stream.

[0098] The second distillation condition is such that the bottom temperature of the light removal tower does not exceed 120°C;

[0099] Optionally, 0-75 wt % of the overhead stream of the light-removal tower is introduced into a pre-deweighting tower for a first material cycle;

[0100] (3) Norbornene refining: introducing the light-removal tower bottom stream obtained in step (2) into a refining tower for third distillation to obtain a refining tower bottom stream and a refining tower top stream,

[0101] Wherein, the conditions of the third distillation are such that the bottom temperature of the refining tower does not exceed 110°C;

[0102] Optionally, the refining tower bottom stream is introduced into a pre-deweighting tower for a second material cycle;

[0103] (4) solvent recovery: introducing the pre-deweight removal tower bottom stream obtained in step (1) into a deweight removal tower, performing a fourth distillation to obtain a deweight removal tower bottom stream and a deweight removal tower top stream, and recycling the deweight removal tower top stream as a recovery solvent; and

[0104] Optionally, (5) intermediate product recovery: separating and recovering the tetracyclododecene and / or dicyclopentadiene in the deheavy tower bottom stream obtained in step (4).

[0105] In the above method, the specific processing methods and conditions of each step are as described above and will not be repeated here.

[0106] The second aspect of the present invention provides a system for separating and purifying norbornene from norbornene synthesis liquid (using the above method), the system comprising a pre-heavy removal tower, a light removal tower and a refining tower;

[0107] The material inlet and outlet of the pre-deweighting tower include: the inlet of the material to be pre-deweighting, the outlet of the pre-deweighting tower bottom logistics and the outlet of the pre-deweighting tower top logistics;

[0108] The material inlet and outlet of the light-removal tower include: the inlet of the material to be removed, the outlet of the bottom logistics of the light-removal tower and the outlet of the top logistics of the light-removal tower;

[0109] The material inlets and outlets of the refining tower include: an inlet for materials to be refined, a refining tower bottom logistics outlet, and a refining tower top logistics outlet;

[0110] Among them, the pre-deheavy tower top logistics outlet of the pre-deheavy tower is connected to the light material inlet to be de-lightened of the light-removing tower, and the light-removing tower bottom logistics outlet of the light-removing tower is connected to the light material inlet to be refined of the refining tower.

[0111] According to some preferred embodiments of the present invention, the refining tower bottom stream outlet of the refining tower is connected to the inlet of the pre-deheaving material to be pre-deheaving tower (to recycle the refining tower bottom stream).

[0112] According to a preferred embodiment of the present invention, the number of theoretical plates of the pre-deweighting tower is 20-55.

[0113] Preferably, the inlet for the material to be pre-deweighted divides the pre-deweighted tower into a distillation section and a stripping section, and the number of theoretical plates of the distillation section of the pre-deweighted tower does not exceed 1 / 2 of its total theoretical plates, preferably does not exceed 1 / 3.

[0114] According to a preferred embodiment of the present invention, the number of theoretical plates of the lightness removal tower is 30-70.

[0115] Preferably, the inlet for the light material to be removed divides the light-removing tower into a distillation section and a stripping section, and the number of theoretical plates of the distillation section of the light-removing tower does not exceed 1 / 2 of the total theoretical plates, and more preferably does not exceed 1 / 3.

[0116] As mentioned above, when part of the light-removing tower overhead stream is recycled, the yield of norbornene can be further improved. According to some preferred embodiments of the present invention, the light-removing tower overhead stream outlet can be divided into two outlets, one of which is connected to the inlet of the pre-deheavy-removing tower to be pre-deheavy-removed material. Preferably, the other is connected to a light component processing device (for processing and discharging the light-removing tower overhead stream) or a light component collecting device (for collecting the light-removing tower overhead stream for further separation or recycling). The flow rate of the light-removing tower overhead stream entering the two light-removing tower overhead stream outlets can be controlled by setting a flow meter or the like. For example, the flow rate of the light-removing tower overhead stream entering the light-removing tower overhead stream outlet connected to the inlet of the pre-deheavy-removing material can be controlled to be 0-75% by weight of the total flow rate of the light-removing tower overhead stream.

[0117] According to a preferred embodiment of the present invention, the number of theoretical plates of the refining tower is 15-60.

[0118] Preferably, the inlet for the material to be refined divides the refining tower into a distillation section and a stripping section, and the number of theoretical plates in the distillation section of the refining tower is not less than 1 / 2 of the total theoretical plates, more preferably not less than 2 / 3.

[0119] In order to realize the recovery and recycling of the solvent and some heavy components (such as dicyclopentadiene, tetracyclododecene, etc.) in the pre-deweight removal tower bottom stream, according to some preferred embodiments of the present invention, the system further comprises a deweight removal tower;

[0120] The material inlet and outlet of the de-weighting tower include: the inlet of the material to be de-weighted, the outlet of the bottom logistics of the de-weighting tower and the outlet of the top logistics of the de-weighting tower;

[0121] The pre-deweighting tower bottom logistics outlet of the pre-deweighting tower is connected with the inlet of the to-be-deweighted material of the deweighting tower.

[0122] Preferably, the deweighting tower has 5-25 theoretical plates.

[0123] More preferably, the inlet of the material to be deweighted divides the deweighting tower into a rectification section and a stripping section, and preferably the number of theoretical plates of the rectification section of the deweighting tower is 1 / 2 of the total number of theoretical plates.

[0124] According to a preferred embodiment of the present invention, the system further comprises an optional solvent recovery device and an optional intermediate product recovery device. "Optional" means that the device can be selectively added to the system provided by the present invention according to actual conditions and needs, and when the optional device is not added, the system can already achieve the purpose of the present invention, and after adding the optional device, a better effect can be obtained, or a new effect can be obtained on the basis of (substantially without affecting) the original effect.

[0125] Preferably, the weight removal tower top stream outlet is connected to a solvent recovery device.

[0126] Preferably, the deweighting tower bottom stream outlet is connected to an intermediate product recovery device. Preferably, the intermediate product recovery device contains a device for separating and recovering tetracyclododecene and / or dicyclopentadiene. For example, it may include a distillation device and / or a depolymerization reaction distillation device.

[0127] According to a particularly preferred embodiment of the present invention, the system comprises a pre-deweighting tower, a lightness removing tower and a refining tower, as well as an optional deweighting tower, an optional solvent recovery device and an optional intermediate product recovery device;

[0128] The material inlet and outlet of the pre-deweighting tower include: the inlet of the material to be pre-deweighting, the outlet of the pre-deweighting tower bottom logistics and the outlet of the pre-deweighting tower top logistics;

[0129] The material inlets and outlets of the light-removal tower include: an inlet for materials to be removed, a bottom stream outlet of the light-removal tower, a top stream outlet I of the light-removal tower, and an optional top stream outlet II of the light-removal tower;

[0130] The material inlets and outlets of the refining tower include: an inlet for materials to be refined, a refining tower bottom logistics outlet, and a refining tower top logistics outlet;

[0131] The material inlet and outlet of the de-weighting tower include: the inlet of the material to be de-weighted, the outlet of the bottom logistics of the de-weighting tower and the outlet of the top logistics of the de-weighting tower;

[0132] The pre-heavy-removal tower top logistics outlet of the pre-heavy-removal tower is connected to the light material inlet of the light-removal tower, and the light-removal tower bottom logistics outlet of the light-removal tower is connected to the material inlet of the refining tower;

[0133] Optionally, the outlet II of the light-removal tower top stream is connected to the inlet of the material to be pre-de-heavy (to achieve the recovery and circulation of part of the light-removal tower top stream. At the same time, the outlet I of the light-removal tower top stream is connected to a corresponding device to achieve the purpose of collecting and / or discharging another part of the light-removal tower top stream);

[0134] Optionally, the outlet of the refining tower bottom stream is connected to the inlet of the material to be pre-de-heavy;

[0135] Optionally, the outlet of the weight removal tower top stream is connected to a solvent recovery device;

[0136] Optionally, the deweighting tower bottom stream outlet is connected to an intermediate product recovery device.

[0137] The features and structures of each part contained in the above system are as described above and will not be repeated here.

[0138] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0139] In the following examples, unless otherwise specified, the reagents used were all commercial products obtained from regular chemical suppliers, and the purity was analytically pure. The flow rate of each step was detected by a mass flow meter, and the top / bottom flow components obtained in each step were analyzed by gas chromatography and the weight proportion of each component was calculated (in Tables 1-10, " / " represents not detected).

[0140] Example 1

[0141] use Figure 1 The system shown in the figure is used to separate norbornene from the norbornene synthesis liquid according to the following method. The norbornene synthesis liquid used in this embodiment is a simplified simulated norbornene synthesis liquid prepared according to the proportion of logistics S-1 in Table 1 with reference to the composition of the industrially produced norbornene synthesis liquid. The logistics flow and composition of each step are detailed in Table 1.

[0142] (1) Pre-deweight removal: The norbornene synthesis liquid S-1 is introduced into the pre-deweight removal tower T-1 for the first distillation to obtain the pre-deweight removal tower bottom stream S-3 and the pre-deweight removal tower top stream S-2.

[0143] The number of theoretical plates of the pre-deweighting tower is 30, and the inlet for the pre-deweighting material is arranged at the 10th theoretical plate from top to bottom.

[0144] The conditions of the first distillation include: top pressure 110 kPa, top temperature 99° C., bottom temperature 120° C., and reflux ratio 3.

[0145] (2) Light removal: The pre-heavy removal tower top stream S-2 is introduced into the light removal tower T-2 for secondary distillation to obtain the light removal tower bottom stream S-5 and the light removal tower top stream S-4.

[0146] The number of theoretical plates of the light-removal tower is 40, and the inlet for the light-removal material is arranged at the 15th theoretical plate from top to bottom.

[0147] The conditions of the second distillation include: tower top pressure 110 kPa, tower top temperature 90° C., tower bottom temperature 102° C., and reflux ratio 30.

[0148] (3) Norbornene refining: The light-removal tower bottoms stream S-5 is introduced into the refining tower T-3 for the third distillation to obtain the refining tower bottoms stream S-7 and the refining tower tops stream S-6. The refining tower bottoms stream S-7 is completely recycled back to the pre-heavy-removal tower and introduced into the inlet of the pre-heavy-removal material.

[0149] The number of theoretical plates of the refining tower is 30, and the inlet for the material to be refined is arranged at the 20th theoretical plate from top to bottom.

[0150] The conditions of the third distillation include: top pressure 50 kPa, top temperature 70° C., bottom temperature 94° C., and reflux ratio 5.

[0151] (4) Solvent recovery: The pre-deweight removal tower bottom stream S-3 is introduced into the deweight removal tower T-4 for the fourth distillation to obtain the deweight removal tower bottom stream S-9 and the deweight removal tower top stream S-8.

[0152] The number of theoretical plates of the deweighting tower is 10, and the inlet for the material to be deweighted is arranged at the 5th theoretical plate from top to bottom.

[0153] The conditions of the fourth distillation include: top pressure 50 kPa, top temperature 88° C., bottom temperature 204° C., and reflux ratio 0.5.

[0154] The de-heavy tower top stream S-8 can be collected and reused as a recovery solvent in the norbornene synthesis process. The de-heavy tower bottom stream S-9 can be further separated and tetracyclododecene and dicyclopentadiene can be recovered and reused in the norbornene synthesis process.

[0155] Table 1

[0156] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 663.9 397.2 7.95 655.9 618.8 37.1 372 25.2 Cyclopentadiene / wt.% 0.04 0.06 / 5.14 2ppm 2.1ppm / / / Toluene / wt.% 36.00 6.51 91.24 0.01 6.59 1.00 99.74 97.43 / Norbornene / wt.% 60.95 93.43 1.00 94.85 93.41 99.00 0.24 1.07 / Tetracyclododecene / wt.% 2.15 / 5.54 / / / / 3.6ppm 87.20 Dicyclopentadiene / wt.% 0.58 / 1.50 / 0.001 / 0.018 1.50 1.44 Tricyclopentadiene / wt.% 0.28 / 0.72 / / / / / 11.36

[0157] It can be seen from the data in Table 1 that in the method of the present invention, the pre-deweighting tower top stream contains 6.5 wt % of toluene, which can effectively reduce the norbornene content in the refining tower bottom stream and prevent it from depolymerizing or further reacting to generate heavy components. In addition, the presence of some toluene in the pre-deweighting tower top stream can effectively control the norbornene content in the pre-deweighting tower bottom stream (only 1 wt %), reducing the loss of norbornene and helping to improve the norbornene yield.

[0158] In addition, the light-removing tower top stream contains 5.14 wt% cyclopentadiene and 94.85 wt% norbornene. If the cyclopentadiene is dimerized into dicyclopentadiene and recycled back to the pre-deweighting tower, the yield of norbornene can be further improved. The purity of norbornene in the refining tower top stream is 99.00%, which can be directly used as a high-purity norbornene product, wherein the impurities contain only 2.1 ppm cyclopentadiene, and the remainder is toluene, which can meet the COC production requirements. Considering the subsequent application needs of norbornene, the refining tower top stream can also be further processed to reduce the toluene content.

[0159] The stream taken out from the bottom of the norbornene refining tower is returned to the pre-deweighting tower, and the norbornene therein can be recovered. The deweighting tower further separates the stream from the bottom of the pre-deweighting tower, and separates the toluene and dicyclopentadiene therein for reuse. From the composition of the stream taken out from the bottom of the deweighting tower, it can be seen that the stream can be further refined to obtain the tetracyclododecene product, and then recycled to the norbornene production process.

[0160] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.16%, and the recovery rate of the solvent is 98.32%.

[0161] Example 2

[0162] The method in Example 1 is adopted, except that the cyclopentadiene content in the light removal tower bottom stream is controlled to be 1 ppm, and the light removal tower top temperature is 81°C. Other operations and conditions are basically the same as those in Example 1. The flow rate and composition of each step are detailed in Table 2. The norbornene synthesis liquid used in this example is a simulated norbornene synthesis liquid prepared according to the proportion of logistics S-1 in Table 2 with reference to the composition of the industrially produced norbornene synthesis liquid.

[0163] Table 2

[0164] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 663.65 397.35 7.99 655.66 618.66 37.0 372 25.35 2-Methyl-1-butene / wt.% 0.03 0.046 / 3.85 / / / / / Isoprene / wt.% 0.01 0.015 / 1.28 / / / / / Cyclopentadiene / wt.% 0.04 0.062 / 5.12 1ppm 1.06ppm / / / Toluene / wt.% 36.00 6.49 91.22 0.01 6.57 1.00 99.76 97.43 / Norbornene / wt.% 60.90 93.38 1.00 89.74 93.43 99.00 0.24 1.07 / Tetracyclododecene / wt.% 2.15 / 5.54 / / / / 3.2ppm 86.84 Dicyclopentadiene / wt.% 0.58 / 1.49 / 0.001 / 0.018 1.47 1.84 Tanrene / wt.% 0.01 / / / / / / 0.027 / Tricyclopentadiene / wt.% 0.28 / 0.72 / / / / / 11.31

[0165] It can be seen from the data in Table 2 that the method of the present invention can reduce the cyclopentadiene content in the norbornene product to about 1 ppm, making it particularly suitable for use in COC production.

[0166] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.2%, and the recovery rate of the solvent is 98.3%.

[0167] Example 3

[0168] use Figure 1 The system shown in the figure is used to separate norbornene from the norbornene synthesis liquid according to the following method. The flow rate and composition of each step are shown in Table 3. The norbornene synthesis liquid used in this embodiment is the same as that in Example 2.

[0169] (1) Pre-deweight removal: The norbornene synthesis liquid S-1 is introduced into the pre-deweight removal tower T-1 for the first distillation to obtain the pre-deweight removal tower bottom stream S-3 and the pre-deweight removal tower top stream S-2.

[0170] The number of theoretical plates of the pre-deweighting tower is 40, and the inlet for the pre-deweighting material is arranged at the 20th theoretical plate from top to bottom.

[0171] The conditions of the first distillation include: tower top pressure 60 kPa, tower top temperature 77.7° C., tower bottom temperature 100.9° C., and reflux ratio 5.

[0172] (2) Light removal: The pre-heavy removal tower top stream S-2 is introduced into the light removal tower T-2 for secondary distillation to obtain the light removal tower bottom stream S-5 and the light removal tower top stream S-4.

[0173] The number of theoretical plates of the light-removal tower is 60, and the inlet for the light-removal material is arranged at the 30th theoretical plate from top to bottom.

[0174] The conditions of the second distillation include: tower top pressure 60 kPa, tower top temperature 62.7° C., tower bottom temperature 83° C., and reflux ratio 20.

[0175] (3) Norbornene refining: The light-removal tower bottoms stream S-5 is introduced into the refining tower T-3 for the third distillation to obtain the refining tower bottoms stream S-7 and the refining tower tops stream S-6. The refining tower bottoms stream S-7 is completely recycled to the inlet of the pre-heavy-removal tower.

[0176] The number of theoretical plates of the refining tower is 50, and the inlet for the material to be refined is set at the 30th theoretical plate from top to bottom.

[0177] The conditions of the third distillation include: tower top pressure 40 kPa, tower top temperature 63.9° C., tower bottom temperature 88.6° C., and reflux ratio 7.

[0178] (4) Solvent recovery: The pre-deweight removal tower bottom stream S-3 is introduced into the deweight removal tower T-4 for the fourth distillation to obtain the deweight removal tower bottom stream S-9 and the deweight removal tower top stream S-8.

[0179] The number of theoretical plates of the deweighting tower is 20, and the inlet for the material to be deweighted is set at the 10th theoretical plate from top to bottom.

[0180] The conditions of the fourth distillation include: tower top pressure 60 kPa, tower top temperature 94.9° C., tower bottom temperature 214.8° C., and reflux ratio 1.

[0181] Table 3

[0182] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 693 393.39 9.96 683.04 620.65 62.39 372 25.35 2-Methyl-1-butene / wt.% 0.03 0.044 / 3.08 / / / / / Isoprene / wt.% 0.01 0.015 / 1.03 / / / / / Cyclopentadiene / wt.% 0.04 0.059 / 4.11 1ppm 1.1ppm / / / Toluene / wt.% 36.00 9.90 92.13 / 10.04 1.00 100 97.43 / Norbornene / wt.% 60.90 89.98 0.0079 91.78 89.96 99.00 5ppm 0.0084 / Tetracyclododecene / wt.% 2.15 / 5.60 / / / / 0.94 86.60 Dicyclopentadiene / wt.% 0.58 / 1.51 / 0.001 / 0.011 1.60 / Tanrene / wt.% 0.01 / 0.026 / / / / 0.028 / Tricyclopentadiene / wt.% 0.28 / 0.73 / / / / / 13.40

[0183] From the data in Table 3, it can be seen that the method of the present invention not only achieves the same separation purpose as Examples 1 and 2, but also controls the top pressure of the pre-de-heavy tower, the light tower and the refining tower, and operates under reduced pressure conditions, which can make the top temperature and the bottom temperature lower, thereby reducing the reaction during the distillation process and better achieving the separation target. Changing the content of solvent toluene in the top stream of the pre-de-heavy tower, that is, changing the distribution ratio of toluene at the top and bottom of the tower does not affect the quality of the norbornene product, which makes the pre-de-heavy tower easier to operate and improves the qualified rate of norbornene products that meet the polymerization grade requirements.

[0184] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.53%, and the recovery rate of the solvent is 98.32%.

[0185] Example 4

[0186] use Figure 1 The system shown in the figure is used to separate norbornene from the norbornene synthesis liquid according to the following method. The flow rate and composition of each step are shown in Table 4. The norbornene synthesis liquid used in this embodiment is the same as that in Example 2.

[0187] (1) Pre-deweight removal: The norbornene synthesis liquid S-1 is introduced into the pre-deweight removal tower T-1 for the first distillation to obtain the pre-deweight removal tower bottom stream S-3 and the pre-deweight removal tower top stream S-2.

[0188] The number of theoretical plates of the pre-deweighting tower is 35, and the inlet for the pre-deweighting material is arranged at the 15th theoretical plate from top to bottom.

[0189] The conditions of the first distillation include: tower top pressure 80 kPa, tower top temperature 86.4° C., tower bottom temperature 109.5° C., and reflux ratio 4.

[0190] (2) Light removal: The pre-heavy removal tower top stream S-2 is introduced into the light removal tower T-2 for secondary distillation to obtain the light removal tower bottom stream S-5 and the light removal tower top stream S-4.

[0191] The number of theoretical plates of the light-removal tower is 50, and the inlet for the light-removal material is arranged at the 25th theoretical plate from top to bottom.

[0192] The conditions of the second distillation include: tower top pressure 80 kPa, tower top temperature 70.7° C., tower bottom temperature 90.8° C., and reflux ratio 25.

[0193] (3) Norbornene refining: The light-removal tower bottoms stream S-5 is introduced into the refining tower T-3 for the third distillation to obtain the refining tower bottoms stream S-7 and the refining tower tops stream S-6. The refining tower bottoms stream S-7 is circulated back to the inlet of the pre-heavy-removal tower.

[0194] The number of theoretical plates of the refining tower is 40, and the inlet for the material to be refined is arranged at the 30th theoretical plate from top to bottom.

[0195] The conditions of the third distillation include: top pressure 70 kPa, top temperature 81.7° C., bottom temperature 103.8° C., and reflux ratio 6.

[0196] (4) Solvent recovery: The pre-deweight removal tower bottom stream S-3 is introduced into the deweight removal tower T-4 for the fourth distillation to obtain the deweight removal tower bottom stream S-9 and the deweight removal tower top stream S-8.

[0197] The number of theoretical plates of the deweighting tower is 10, and the inlet for the material to be deweighted is set at the 5th theoretical plate from top to bottom.

[0198] The conditions of the fourth distillation include: tower top pressure 40 kPa, tower top temperature 82.3° C., tower bottom temperature 200.5° C., and reflux ratio 0.5.

[0199] Table 4

[0200]

[0201]

[0202] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.7%, and the recovery rate of the solvent is 98.3%.

[0203] Example 5

[0204] The method in Example 2 is different in that the cyclopentadiene content in the light removal tower bottom stream is controlled to be about 5 ppm. Except for the change in the flow rate of the light removal tower top stream S-4, other process parameters do not change much. The flow rate and composition of each step are shown in Table 5.

[0205] Table 5

[0206] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 663.65 397.34 7.10 656.55 619.56 36.99 372 25.34 2-Methyl-1-butene / wt.% 0.03 0.046 / 4.33 / / / / / Isoprene / wt.% 0.01 0.015 / 1.44 / / / / / Cyclopentadiene / wt.% 0.04 0.062 / 5.72 5ppm 5.3ppm / / / Toluene / wt.% 36.00 6.49 91.22 0.01 6.56 1.00 99.76 97.43 / Norbornene / wt.% 60.90 93.38 1 88.50 93.44 99.00 0.24 1.07 / Tetracyclododecene / wt.% 2.15 / 5.54 / / / / 3.2ppm 86.87 Dicyclopentadiene / wt.% 0.58 / 1.49 / 0.001 / 0.018 1.47 1.80 Tanrene / wt.% 0.01 / / / / / / 0.027 / Tricyclopentadiene / wt.% 0.28 / 0.72 / / / / / 11.31

[0207] From the data in Table 5, it can be seen that the bottom stream of the light removal tower contains 5 ppm cyclopentadiene, which will be carried to the top stream norbornene product of the refining tower. The cyclopentadiene content is 5.3 ppm, which cannot meet the COC production requirements. Therefore, the operation of the light removal tower should be controlled so that the cyclopentadiene meets the requirements.

[0208] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.36%, and the recovery rate of the solvent is 98.32%.

[0209] Example 6

[0210] The method in Example 1 is adopted, except that in step (3), the refining tower bottom stream S-7 is only collected in a storage device and is not recycled to the pre-deweighting tower. The stream flow and composition of each step are detailed in Table 6.

[0211] Table 6

[0212] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 657.69 366.31 7.89 649.8 619.1 30.7 337 29.31 Cyclopentadiene / wt.% 0.04 0.06 / 5.17 2ppm 2.1ppm / / / Toluene / wt.% 36.00 5.60 90.59 0.01 5.67 1 99.76 98.46 0.06 Norbornene / wt.% 60.95 94.34 1 94.82 94.33 99 0.24 1.09 / Tetracyclododecene / wt.% 2.15 / 6.01 / / / / 1.4ppm 75.12 Dicyclopentadiene / wt.% 0.58 / 1.62 / 0.001 / 0.021 0.46 15.03 Tricyclopentadiene / wt.% 0.28 / 0.78 / / / / / 9.78

[0213] By comparing the data in Table 1 and Table 6, it can be seen that when the refining tower bottom stream S-7 is not recycled, the purity of the obtained norbornene product and the content of impurities such as cyclopentadiene therein are roughly the same, which can also meet the needs of COC production.

[0214] However, it is obvious that a lot of toluene is discarded in the refining tower bottom stream, and norbornene is also lost, which is not as economical as Example 1. If the refining tower bottom stream S-7 is directly discarded after harmless treatment, on the one hand, the cost of environmental protection treatment is increased, and on the other hand, a large amount of toluene is wasted, which increases the overall cost of norbornene production.

[0215] Example 7

[0216] The method in Example 2 is adopted, except that two outlets for the top stream of the light-removing tower are provided in the light-removing tower, so that the top stream S-4 of the light-removing tower takes out 50% of the original flow, and the rest is returned to the inlet of the pre-deheavy-removing tower for circulation. The other operations and conditions are basically the same as those in Example 2. The stream flow and composition of each step are detailed in Table 7.

[0217] Table 7

[0218] Logistics components S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 <![CDATA[Mass flow rate / kg·h -1 > 1024 667.13 397.31 7.98 659.15 622.69 36.46 372 25.31 2-Methyl-1-butene / wt.% 0.03 0.09 / 7.68 / / / / / Isoprene / wt.% 0.01 0.03 / 2.56 / / / / / Cyclopentadiene / wt.% 0.04 0.12 / 10.22 1ppm 1.06ppm / / / Toluene / wt.% 36.00 6.39 91.22 0.008 6.46 1.00 99.76 97.42 / Norbornene / wt.% 60.90 93.37 1.00 79.53 93.53 99.00 0.24 1.07 / Tetracyclododecene / wt.% 2.15 / 5.54 / / / / 3.3ppm 86.98 Dicyclopentadiene / wt.% 0.58 / 1.49 / 0.002 / 0.036 1.48 1.68 Tanrene / wt.% 0.01 / / / / / / 0.027 / Tricyclopentadiene / wt.% 0.28 / 0.72 / / / / / 11.33

[0219] It can be seen from the data in Table 7 that in the method of the present invention, 50% of the original flow rate is used to extract the top logistics from the top of the light-removing tower, and the rest is returned to the inlet of the pre-heavy-removing tower, which not only avoids the accumulation of these light components in the system, but also improves the yield of norbornene, and can also increase the concentration of cyclopentadiene to 10.22%, which is dimerized into dicyclopentadiene in the circulation process, which obviously improves the utilization rate of raw materials.

[0220] According to the calculation of the logistics flow rate, the yield of norbornene in this example is 98.85%, and the product quality remains unchanged.

[0221] Comparative Example 1

[0222] This comparative example is used to illustrate the influence of the distribution ratio of toluene in the top stream and bottom stream of the pre-deweighting tower on the energy consumption of the reboiler thereof.

[0223] The method in Example 2 was followed, except that the conditions of the first distillation were controlled so that the toluene content in the pre-deweight removal tower top stream S-2 was 10 wt%, 30 wt% and 50 wt%, respectively, and the remaining operations and conditions were the same as in Example 2. The heat load of the reboiler at the bottom of the pre-deweight removal tower is listed in Table 8.

[0224] Table 8

[0225] Proportion of toluene in the overhead stream of the pre-deweighting tower 10wt.% 30wt.% 50wt.% <![CDATA[Mass flow rate of toluene in the overhead stream of the pre-deweighting tower / kg·h -1 > 37.325 110.94 183.269 <![CDATA[Mass flow rate of overhead stream from pre-depressurization tower / kg·h -1 > 655 735 808 Heat load of reboiler at the bottom of pre-deweighting tower / kW 248.1 278.0 308.6

[0226] From the data in Table 8, it can be seen that the heat load of the pre-deweighting tower alone increases with the increase in the distribution ratio of toluene in the pre-deweighting tower overhead stream, and it is easy to predict that the heat load of other subsequent equipment will also increase accordingly. Combined with the contents of Examples 1-7, it can be seen that it is reasonable and economical to retain a certain amount of toluene in the pre-deweighting tower overhead stream and appropriately control the content of toluene in the pre-deweighting tower overhead stream, which is very important for reducing the energy consumption of the norbornene purification process.

[0227] Comparative Example 2

[0228] This comparative example is used to illustrate the influence of the operating temperature of the lightness removal tower on the lightness removal tower and the refining tower.

[0229] The method in Example 2 was adopted, except that the temperature of the top of the light removal tower was adjusted. The specific flow rate, temperature and composition of each step are shown in Table 9. The remaining operations and conditions are basically the same as in Example 2.

[0230] Table 9

[0231]

[0232] As can be seen from Table 9 data, when the lightness removal tower operating temperature is high, the lightness removal tower body temperature and the tower bottom temperature are high, and cyclopentadiene undergoes dimerization reaction in the lightness removal tower to generate dicyclopentadiene, so that dicyclopentadiene is contained in the tower top stream, and the dicyclopentadiene at the bottom of the tower undergoes depolymerization reaction to generate cyclopentadiene, so that the tower bottom stream contains higher cyclopentadiene and dicyclopentadiene. If long-term operation, cyclopentadiene also can react with norbornene to generate heavier components such as tetracyclododecene. The lightness removal tower bottom stream enters the treating tower, so that the norbornene product obtained at the treating tower top contains a higher content of cyclopentadiene (16ppm), which cannot reach the COC polymerization raw material standard.

[0233] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 98.4%, and the recovery rate of the solvent is 98.3%.

[0234] Comparative Example 3

[0235] This comparative example is used to illustrate the operating conditions when no or very little toluene is produced in the pre-deweighting tower top stream.

[0236] The method in Example 2 is adopted, except that very little toluene is produced from the pre-deheavy tower top stream, and the norbornene content in the bottom stream is maintained at 1%. Under this condition, the reflux ratio needs to be increased from 3 in Example 2 to 10, and the reboiler heat load is increased to 611.4 kW. Compared with Example 2, the steam consumption under this condition increases by about 150%. In addition, because the toluene contained in the light tower bottom stream is very small, the refining tower bottom stream can only be produced intermittently, and the operating condition of not circulating back is investigated.

[0237] The logistics flow and composition of each step are detailed in Table 10.

[0238] Table 10

[0239]

[0240] It can be seen from the data in Table 10 that the bottom material flow of the refining tower is very small and can only be produced intermittently. This will inevitably cause the accumulation of heavy components such as dicyclopentadiene, resulting in a very high temperature at the bottom of the tower, which will prompt the dimerization and depolymerization of dicyclopentadiene in the tower body, resulting in a high level of impurities cyclopentadiene and dicyclopentadiene in the norbornene product produced from the top of the tower, making it difficult to meet the requirements for COC polymerization.

[0241] According to the calculation of the flow rate of the logistics, the yield of norbornene in this example is 95.2%, and the recovery rate of the solvent is 98.1%.

[0242] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for separating and purifying polymerization-grade norbornene with high yield, characterized in that: The method comprises: (1) Pre-deweight removal: The norbornene synthesis liquid generated by the reaction of a toluene solution of dicyclopentadiene with ethylene is introduced into a pre-deweight removal tower for first distillation to obtain a pre-deweight removal tower bottom stream and a pre-deweight removal tower top stream. wherein the conditions of the first distillation are such that the toluene content in the pre-deweighting tower overhead stream is 1-25 wt %; (2) Light removal: the pre-heavy removal tower top stream obtained in step (1) is introduced into a light removal tower for secondary distillation to obtain a light removal tower bottom stream and a light removal tower top stream. The second distillation condition is such that the bottom temperature of the light removal tower does not exceed 120°C; (3) Norbornene refining: introducing the light-removal tower bottom stream obtained in step (2) into a refining tower for third distillation to obtain a refining tower bottom stream and a refining tower top stream, The conditions of the third distillation are such that the bottom temperature of the refining tower does not exceed 110°C.

2. The method according to claim 1, wherein: In step (1), the conditions of the first distillation are such that the toluene content in the pre-deweighting tower overhead stream is 3-15 wt %; Preferably, the conditions of the first distillation are such that the content of norbornene in the pre-deweighting tower bottom stream does not exceed 3 wt%, preferably does not exceed 2 wt%, more preferably does not exceed 1 wt%.

3. The method according to claim 1 or 2, wherein: The number of theoretical plates of the pre-deweighting tower is 20-55, and the conditions of the first distillation preferably include: the tower top pressure is 50-200 kPa, and the tower top temperature is 50-115° C.; Preferably, the conditions of the first distillation also include: the tower bottom temperature is 85-130°C, preferably the tower bottom temperature does not exceed 120°C; More preferably, the reflux ratio of the first distillation is 1-10, preferably 2-6.

4. The method according to claim 1, wherein: In step (2), the conditions of the second distillation are such that the content of light components in the light removal tower bottom stream does not exceed 20 ppm, preferably does not exceed 10 ppm, and more preferably does not exceed 2 ppm; Preferably, the conditions of the second distillation are such that the content of cyclopentadiene in the light-removal tower bottom stream does not exceed 10 ppm, preferably does not exceed 5 ppm, and more preferably does not exceed 1 ppm.

5. The method according to claim 1 or 4, wherein: The number of theoretical plates of the light-removal tower is 30-70, and the conditions of the second distillation preferably include: the tower top pressure is 40-120 kPa, and the tower top temperature is 50-100° C.; Preferably, the conditions of the second distillation also include: a tower bottom temperature of 80-110°C, preferably a tower bottom temperature not exceeding 105°C; More preferably, the reflux ratio of the second distillation is 8-40, preferably 20-40.

6. The method according to claim 1, wherein: In step (3), the conditions of the third distillation are such that the content of dicyclopentadiene and / or tetracyclododecene in the refining tower top stream does not exceed 10 ppm, preferably does not exceed 5 ppm, and more preferably does not exceed 1 ppm.

7. The method according to claim 1 or 6, wherein: The number of theoretical plates of the refining tower is 15-60. Preferably, the third distillation is operated under reduced pressure conditions. More preferably, the conditions of the third distillation include: a tower top pressure of 20-80 kPa and a tower top temperature of 45-90° C. Preferably, the conditions of the third distillation further include: a tower bottom temperature of 65-110°C, preferably a tower bottom temperature of 75-95°C; More preferably, the reflux ratio of the third distillation is 2-12, preferably 3-7.

8. The method according to any one of claims 1 to 7, wherein: The method further comprises: (4) solvent recovery: introducing the pre-deweighting tower bottom stream obtained in step (1) into a deweighting tower, performing a fourth distillation to obtain a deweighting tower bottom stream and a deweighting tower top stream, and recycling the deweighting tower top stream as a recovery solvent; Preferably, the conditions of the fourth distillation are such that the content of tetracyclododecene in the weight removal tower overhead stream does not exceed 1 wt %; Preferably, the conditions of the fourth distillation are such that the content of dicyclopentadiene in the deheavy tower bottom stream does not exceed 2 wt%.

9. The method according to claim 1 or 8, wherein: In step (4), the number of theoretical plates of the deweighting tower is 5-25, and the conditions of the fourth distillation preferably include: the tower top pressure is 20-80 kPa, and the tower top temperature is 55-120° C.; Preferably, the conditions of the fourth distillation further include: a tower bottom temperature of 150-250°C, preferably a tower bottom temperature of 180-220°C; More preferably, the reflux ratio of the fourth distillation is 0.2-3, preferably 0.3-1.

10. The method according to any one of claims 1 to 9, wherein: The method further comprises: (5) intermediate product recovery: separating and recovering tetracyclododecene and / or dicyclopentadiene in the deweighting tower bottom stream obtained in step (4), preferably, the separation method is selected from distillation and / or depolymerization reaction distillation; And / or, the method further comprises: (6) Material circulation: 0-75 wt % of the de-lightening tower top stream obtained in step (2) is introduced into the pre-de-lightening tower, and / or, the refining tower bottom stream obtained in step (3) is introduced into the pre-de-lightening tower.

11. A system for separating and purifying norbornene from a norbornene synthesis liquid, characterized in that: The system includes a pre-heavy removal tower, a light removal tower and a refining tower; The material inlet and outlet of the pre-deweighting tower include: the inlet of the material to be pre-deweighting, the outlet of the pre-deweighting tower bottom logistics and the outlet of the pre-deweighting tower top logistics; The material inlet and outlet of the light-removal tower include: the inlet of the material to be removed, the outlet of the bottom logistics of the light-removal tower and the outlet of the top logistics of the light-removal tower; The material inlets and outlets of the refining tower include: an inlet for materials to be refined, a refining tower bottom logistics outlet, and a refining tower top logistics outlet; Among them, the top logistics outlet of the pre-deheavy-removing tower is connected to the inlet of the light material to be removed of the light material removal tower, and the bottom logistics outlet of the light material removal tower is connected to the inlet of the material to be refined of the refining tower. Preferably, the bottom logistics outlet of the refining tower is connected to the inlet of the material to be pre-deheavy-removed.

12. The system according to claim 11, wherein: The number of theoretical plates of the pre-deweighting tower is 20-55; Preferably, the inlet of the material to be pre-deweighted divides the pre-deweighting tower into a distillation section and a stripping section, and the number of theoretical plates of the distillation section of the pre-deweighting tower does not exceed 1 / 2 of the total theoretical plates, preferably does not exceed 1 / 3; And / or, the number of theoretical plates of the lightness removal tower is 30-70; Preferably, the inlet of the light material to be removed divides the light-removing tower into a rectifying section and a stripping section, and the number of theoretical plates of the rectifying section of the light-removing tower does not exceed 1 / 2 of the total theoretical plates, preferably does not exceed 1 / 3; Preferably, the outlet of the top stream of the de-lightening tower is divided into two outlets, one of which is connected to the inlet of the pre-de-heavy material to be pre-de-heavy material of the pre-de-heavy material removal tower, and the other is connected to the inlet of the material to be refined of the refining tower; And / or, the number of theoretical plates of the refining tower is 15-60; Preferably, the inlet for the material to be refined divides the refining tower into a distillation section and a stripping section, and the number of theoretical plates in the distillation section of the refining tower is not less than 1 / 2 of the total theoretical plates, preferably not less than 2 / 3 of the total theoretical plates.

13. The system according to claim 11, wherein: The system also includes a deweighting tower; The material inlet and outlet of the de-weighting tower include: the inlet of the material to be de-weighted, the outlet of the bottom logistics of the de-weighting tower and the outlet of the top logistics of the de-weighting tower; The pre-deweighting tower bottom logistics outlet of the pre-deweighting tower is connected to the inlet of the to-be-deweighted material of the deweighting tower; Preferably, the deweighting tower has 5-25 theoretical plates.

14. The system according to any one of claims 11 to 13, wherein: The system also includes an optional solvent recovery unit and an optional intermediate product recovery unit; Preferably, the weight removal tower top stream outlet is connected to a solvent recovery device; Preferably, the deweighting tower bottom stream outlet is connected to an intermediate product recovery device, and preferably the intermediate product recovery device contains a device for separating and recovering tetracyclododecene and / or dicyclopentadiene, and preferably the intermediate product recovery device comprises: a distillation device and / or a depolymerization reaction distillation device.

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