Method and system for separating and purifying norbornene

Abstract

The invention relates to the technical field of separation and purification, and discloses a method and a system for separating and purifying norbornene. According to the method provided by the invention, the light components and the heavy components of the norbornene synthetic liquid are sequentially removed, and the high-purity norbornene product can be obtained by controlling the treatment mode and conditions in the removal process, so that the method has the advantages that the norbornene product is high in yield and purity, the treatment process is easy to control and manage, and the like; the method is suitable for industrial popularization.

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 norbornene. Background Art

[0002] Norbornene is an important raw material for the preparation of cycloolefin copolymers (COC), which are usually synthesized by non-ring-opening polymerization with α-olefins such as ethylene, propylene, and styrene under the action of Ziegler-Natta catalysts or metallocene catalysts. COC is an amorphous transparent polymer material with a ring structure. It has excellent high transparency, high heat resistance and chemical inertness, and is widely used in the fields of optical materials, packaging materials, medical fields, and communications.

[0003] The purity of norbornene has a great influence on the transparency of the obtained COC product. If insufficiently pure norbornene is used as a raw material, the obtained COC product will have the defect of insufficient transparency, which will affect subsequent applications and the quality of related products. Therefore, the separation and purification of norbornene is very important for obtaining high-quality norbornene products.

[0004] Since the synthetic solution of norbornene includes unreacted raw materials, new components produced by the reaction, impurities introduced by the raw materials and their products, as well as impurities produced by side reactions, the composition is complex. Moreover, some of the impurities will be mutually converted under certain conditions during the separation process, making it difficult to separate and purify norbornene. In addition, the process flow for obtaining high-purity norbornene is long, resulting in high cost and high energy consumption, which is not conducive to industrial application.

[0005] However, current research on norbornene mainly focuses on the synthesis method, and there is little research on how to subsequently separate and obtain high-purity norbornene. In particular, there are almost no reports on the development of a norbornene purification process that is suitable for industrial application, has a short process flow, and has low energy consumption and cost. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of the prior art in that the separation of high-purity norbornene is difficult and the process is complicated, and to provide a method and system for separating and purifying norbornene. The method provided by the present invention can obtain a high-purity norbornene product by sequentially removing light components and heavy component impurities from norbornene, and has the advantages of simple process, easy control of conditions, high yield, high product purity, etc., and is suitable for industrial promotion and application.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for separating and purifying norbornene, the method comprising:

[0008] (1) Light removal: introducing the norbornene synthesis liquid into a light removal tower for first distillation to obtain a light removal tower top stream and a light removal tower bottom stream;

[0009] (2) Refining: introducing the light-removal tower bottom stream obtained in step (1) into a refining tower for secondary distillation to obtain a refining tower top stream and a refining tower bottom stream;

[0010] The operating conditions of the first distillation are such that the bottom temperature of the tower does not exceed 110°C, and the operating conditions of the second distillation are such that the bottom temperature of the refining tower does not exceed 110°C.

[0011] A second aspect of the present invention provides a system for separating and purifying norbornene, the system comprising a lightness removal tower and a refining tower;

[0012] The material inlets and outlets of the light-removal tower include: a norbornene synthesis liquid inlet, a light-removal tower top stream outlet, and a light-removal tower bottom stream outlet;

[0013] The material inlets and outlets of the refining tower include: an inlet for materials to be refined, an outlet for the top of the refining tower and an outlet for the bottom of the refining tower;

[0014] Among them, the outlet of the bottom logistics of the light removal tower is connected with the inlet of the material to be refined.

[0015] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0016] (1) In the method provided by the present invention, the temperature of the distillation tower body and the bottom of the tower is cleverly controlled during the light and heavy removal processes to reduce the occurrence of side reactions during the purification process, thereby achieving the purpose of separating and obtaining a high-purity norbornene product by subjecting the norbornene synthesis liquid to a two-step "light removal-heavy removal" treatment, simplifying the purification process, reducing the equipment construction, maintenance and management costs, and being more suitable for industrial production applications.

[0017] (2) The method provided by the present invention preferably also includes the recovery and recycling of solvents and other raw materials for norbornene synthesis, which further reduces the cost of raw materials, improves resource utilization, improves corporate benefits and meets the needs of green and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the system for separating and purifying norbornene used in Example 1.

[0019] Description of Reference Numerals

[0020] T-1: lightness removal tower; T-2: refining tower; T-3: solvent recovery tower;

[0021] S-1: norbornene synthesis liquid; S-2: light removal tower top logistics; S-3: light removal tower bottom logistics; S-4: refining tower top logistics (norbornene product logistics); S-5: refining tower bottom logistics; S-6: recovery tower top logistics (recovery solvent); S-7: recovery tower bottom logistics. DETAILED DESCRIPTION

[0022] 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.

[0023] 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 needs 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 8 ppm, for example, 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, or any intermediate value between any two of the above values).

[0024] In the present invention, unless otherwise specified, the theoretical plate number is obtained by experiments using a general determination method in the separation field.

[0025] 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.

[0026] In the present invention, unless otherwise specified, "ppm" means one part per million by mass, and 100 ppm = 0.01% by weight.

[0027] When the solvent-based method is used to synthesize norbornene, the obtained norbornene synthesis liquid contains, in addition to norbornene and solvent (usually toluene), unreacted raw material cyclopentadiene and heavy components with boiling points higher than norbornene, such as dicyclopentadiene, tetracyclododecene, tricyclopentadiene, etc. 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, resulting in the problem of being difficult to completely remove impurities therein when extracting norbornene from the norbornene synthesis liquid, and the purity of the norbornene product is not enough, and the problem of being unable to meet the production needs of COC. Moreover, in order to remove impurities as much as possible, especially for the light and heavy impurities that may be mutually converted in the purification process such as cyclopentadiene and dicyclopentadiene, which have a greater impact on COC synthesis, it is usually caused that the purification process is longer and the energy consumption is higher, making the difficulty of production management and promotion greater.

[0028] The inventors of the present invention cleverly discovered during the research process that in the process of obtaining norbornene from norbornene synthesis liquid by adopting the two-step treatment of "light component removal-heavy component removal", the bottom temperature of the distillation tower is very important for the quality of the norbornene product finally obtained. By controlling the temperature of the distillation tower body and the bottom of the tower respectively in the process of removing light component and heavy component impurities, the problem of mutual conversion of heavy component and light component impurities in the purification process can be avoided, and a high-purity norbornene product can be directly obtained, which simplifies the processing flow, reduces energy consumption and equipment construction and management costs, and is easier to promote industrialization.

[0029] Based on the above findings, the first aspect of the present invention provides a method for separating and purifying norbornene, the method comprising:

[0030] (1) Light removal: introducing the norbornene synthesis liquid into a light removal tower for first distillation to obtain a light removal tower top stream and a light removal tower bottom stream;

[0031] (2) Refining: introducing the light-removal tower bottom stream obtained in step (1) into a refining tower for secondary distillation to obtain a refining tower top stream and a refining tower bottom stream;

[0032] The operating conditions of the first distillation are such that the bottom temperature of the tower does not exceed 110°C, and the operating conditions of the second distillation are such that the bottom temperature of the refining tower does not exceed 110°C.

[0033] 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.

[0034] In the present invention, the purpose of step (1) is to remove light component impurities in the norbornene synthesis liquid. In order to prevent the light components from entering the norbornene product with the light removal tower bottom stream, so that the norbornene product is difficult to meet the COC synthesis needs, the content of light components (especially cyclopentadiene) in the light removal tower bottom stream should be strictly controlled during the first distillation process. In addition, in order to reduce the loss of norbornene, the content of norbornene in the light removal tower top stream should also be controlled.

[0035] According to a preferred embodiment of the present invention, in step (1), the conditions of the first distillation are such that the cyclopentadiene content in the light-removal tower bottom stream does not exceed 10 ppm, preferably does not exceed 3 ppm.

[0036] According to a preferred embodiment of the present invention, in step (1), the conditions of the first distillation are such that the amount of norbornene entering the lightness removal tower overhead stream does not exceed 5% by weight of the norbornene in the synthetic liquid, for example, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, 0.1%, 0.05%, 0.01%, 0%, or any intermediate value between any two of the above values.

[0037] Preferably, the conditions of the first distillation are such that the amount of norbornene entering the top stream of the light removal tower does not exceed 3 wt%.

[0038] In the method provided by the present invention, the toluene in the norbornene synthesis liquid can be recovered by subsequent treatment and recycled to the norbornene synthesis process, thereby reducing the overall cost of norbornene synthesis and purification and improving resource utilization. In order to improve the purity of the norbornene product, reduce the loss of toluene, and improve the economic benefits of the overall process, preferably, the conditions of the first distillation are such that the toluene content in the light removal tower overhead stream does not exceed 6% by weight, preferably not more than 2% by weight.

[0039] In order to make the component contents in the light-removal tower top stream and the light-removal tower bottom stream meet the above requirements, according to a preferred embodiment of the present invention, in step (1), the number of theoretical plates of the light-removal tower is 15-50, preferably 25-50.

[0040] Preferably, the conditions of the first distillation include: a tower top pressure of 50-120 kPa, and a tower top temperature of 45-95°C.

[0041] More preferably, the conditions of the first distillation include: a tower top pressure of 50-115 kPa, and a tower top temperature of 55-95°C.

[0042] In order to minimize or avoid the reaction of components contained in the light-removal tower bottom stream, the tower bottom temperature should be controlled not to be too high during the first distillation. Preferably, the conditions of the first distillation also include: the tower bottom temperature is 75-110°C, preferably 80-110°C.

[0043] Preferably, the reflux ratio of the first distillation is 5-30, preferably 10-30, more preferably 10-25.

[0044] In order to prevent the light components from entering the bottom stream of the light removal tower and affecting the purity and quality of the norbornene product, according to a preferred embodiment of the present invention, the norbornene synthesis liquid is fed into the middle and upper part of the light removal tower. That is, the feed port position can be set at or above 1 / 2 position of the packing or tray from the upper end, preferably at 1 / 10-1 / 2 position from the upper end.

[0045] According to a preferred embodiment of the present invention, the light-removal tower top stream obtained in step (1) mainly contains light components such as cyclopentadiene and a small amount of norbornene, and may also contain a very small amount of toluene and heavy components.

[0046] According to a preferred embodiment of the present invention, the light-removal tower bottom stream obtained in step (1) contains norbornene, toluene and heavy components (such as dicyclopentadiene, tetracyclododecene, etc.).

[0047] In the present invention, the purpose of step (2) is to remove the heavy components in the bottom stream of the light removal tower, thereby obtaining a (high-purity) norbornene product. In order to improve the purity of the norbornene product, the content of the heavy components entering the norbornene product stream (i.e., the refining tower top extraction stream) during the second distillation process should be strictly controlled. In addition, in order to avoid norbornene loss and improve the yield of norbornene product, the content of norbornene entering the bottom stream of the refining tower during the second distillation process should also be controlled.

[0048] According to a preferred embodiment of the present invention, in step (2), the conditions of the second distillation are such that the content of norbornene in the refining tower bottom stream does not exceed 3% by weight, preferably does not exceed 2% by weight. For example, it may be 2% by weight, 1.9% by weight, 1.8% by weight, 1.6% by weight, 1.5% by weight, 1.2% by weight, 1% by weight, 0.8% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, 0.01% by weight, 0% by weight, or any intermediate value between any two of the above values.

[0049] According to a preferred embodiment of the present invention, in step (2), the conditions of the second distillation are such that the toluene content in the norbornene product stream does not exceed 1 wt%, preferably does not exceed 0.5 wt%, and more preferably does not exceed 0.2 wt%.

[0050] In order to make the component contents in the refining tower bottom stream and the norbornene product stream meet the above requirements, according to a preferred embodiment of the present invention, in step (2), the number of theoretical plates of the refining tower is 15-50.

[0051] Due to the depolymerization reaction of heavy components such as dicyclopentadiene and tetracyclododecene at a higher temperature, dicyclopentadiene is depolymerized into cyclopentadiene, and tetracyclododecene is depolymerized into cyclopentadiene and norbornene, and cyclopentadiene will react with the material containing carbon-carbon double bonds in the heavy component to produce Diels-alder diene synthesis reaction, generating 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 refining tower is preferably operated under reduced pressure, normal pressure or slightly pressurized conditions, and more preferably operated under normal pressure or reduced pressure conditions. In order to reduce the reaction of materials in the second distillation process, the temperature at the bottom of the refined tower should not be too high.

[0052] Preferably, the conditions of the second distillation include: a tower top pressure of 30-90 kPa and a tower top temperature of 45-90°C.

[0053] More preferably, the conditions of the second distillation include: a tower top pressure of 45-85 kPa, a tower top temperature of 60-90° C., more preferably 70-90° C. For example, it can be 70° C., 75° C., 80° C., 85° C., 90° C., or any intermediate value between any two of the above values.

[0054] Preferably, the second distillation conditions also include: the tower bottom temperature is 75-110°C, preferably 90-110°C, for example, 90°C, 95°C, 100°C, 105°C, 110°C, or any intermediate value between any two of the above values.

[0055] Preferably, the reflux ratio of the second distillation is 1.5-8.

[0056] According to a preferred embodiment of the present invention, the logistics extracted from the top of the refinement tower in step (2) mainly contains norbornene, and its purity is high, which can meet the requirements for synthesizing COC, and can be directly packaged and used as a high-purity norbornene product. The main impurity in the top stream of the refinement tower is toluene. Since toluene is also required as a solvent when synthesizing COC, a small amount of toluene does not affect the quality of the norbornene product obtained by the method of the present invention. In order to meet the production needs of different products, according to actual production requirements, in order to further reduce the impurity content in the norbornene product logistics, step (2) can also further include the operation of removing toluene from the norbornene product logistics, or the toluene content in the norbornene product logistics can be controlled by adjusting the conditions of the second distillation.

[0057] According to a preferred embodiment of the present invention, the refined bottom stream obtained in step (2) contains toluene and heavy components (such as dicyclopentadiene, tetracyclododecene, etc.).

[0058] 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.

[0059] For the above purpose, according to a preferred embodiment of the present invention, the method further comprises:

[0060] (3) Solvent recovery: The refining tower bottom stream obtained in step (2) is introduced into a solvent recovery tower for a third distillation to obtain a recovery tower top stream and a recovery tower bottom stream, and the recovery tower top stream is recycled as a recovery solvent.

[0061] In the present invention, the purpose of step (3) is to recycle the toluene in the refining tower bottom stream, improve resource utilization, reduce waste, enable the whole process to reach the level of green chemical industry, and improve economic benefits. Toluene can be reused in the norbornene production process to dissolve dicyclopentadiene after recovery. Therefore, the recovery solvent obtained in step (3) 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 third distillation process. However, the recovery solvent should be avoided as much as possible to contain 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 third distillation can be relatively loose, without too strict control.

[0062] Based on the above principles, according to a preferred embodiment of the present invention, the conditions of the third distillation are such that the content of tetracyclododecene in the recovered tower top material does not exceed 0.1% by weight, preferably does not exceed 0.5% by weight, for example, it may be 0.5%, 0.1%, 0.05%, 0.01%, 0.005%, 0.001% by weight, or any intermediate value between any two of the above values.

[0063] In order to improve the utilization rate of dicyclopentadiene, preferably, the conditions of the third distillation are such that the content of dicyclopentadiene in the recovered bottom stream does not exceed 15 wt %, for example, it may be 15 wt %, 12 wt %, 10 wt %, 8 wt %, 5 wt %, 3 wt %, 1 wt %, 0.5 wt %, 0.1 wt %, or any intermediate value between any two of the above values.

[0064] Preferably, the conditions of the third distillation are such that the content of dicyclopentadiene in the recovered tower bottom stream does not exceed 10 wt%.

[0065] According to a preferred embodiment of the present invention, the number of theoretical plates of the solvent recovery tower is 5-20.

[0066] In order to avoid reaction of materials in the solvent recovery tower and reduce coking, the third distillation is preferably carried out under reduced pressure or normal pressure.

[0067] Preferably, the conditions of the third distillation include: the tower top pressure is 30-80 kPa, and the tower top temperature is 55-110° C. Preferably, the tower top pressure is 30-70 kPa, and the tower top temperature is 70-100° C.

[0068] Preferably, the conditions of the third distillation further include: the tower bottom temperature is 150-230°C, preferably 175-230°C.

[0069] Preferably, the reflux ratio of the third distillation is 0.2-3, preferably 0.2-1.5.

[0070] According to a preferred embodiment of the present invention, the recovery tower top stream obtained in step (3) mainly contains toluene. In addition to toluene, it may also contain dicyclopentadiene and (a small amount of) components with a boiling point lower than dicyclopentadiene (such as cyclopentadiene, etc.).

[0071] According to a preferred embodiment of the present invention, the recovery tower bottom stream obtained in step (3) contains heavy components having a boiling point higher than that of toluene (such as tetracyclododecene, etc.).

[0072] According to a preferred embodiment of the present invention, the method may further include:

[0073] (4) Recovery of intermediate products: Separating and recovering tetracyclododecene and / or dicyclopentadiene in the recovery tower bottom stream obtained in step (3), preferably, the separation method is selected from distillation and / or reactive distillation.

[0074] A second aspect of the present invention provides a system for separating and purifying norbornene, the system comprising a lightness removal tower and a refining tower;

[0075] The material inlets and outlets of the light-removal tower include: a norbornene synthesis liquid inlet, a light-removal tower top stream outlet, and a light-removal tower bottom stream outlet;

[0076] The material inlets and outlets of the refining tower include: an inlet for materials to be refined, an outlet for the top of the refining tower and an outlet for the bottom of the refining tower;

[0077] Among them, the outlet of the bottom logistics of the light removal tower is connected with the inlet of the material to be refined.

[0078] According to a preferred embodiment of the present invention, the number of theoretical plates of the lightness removal tower is 15-50.

[0079] Preferably, the inlet of the norbornene synthesis liquid divides the lightness removal tower into a distillation section and a stripping section, wherein the number of theoretical plates of the distillation section of the lightness removal tower does not exceed 1 / 2 of the total theoretical plates (i.e., the inlet is set in the middle or upper middle part of the lightness removal tower), preferably 1 / 10-1 / 2.

[0080] According to a preferred embodiment of the present invention, the number of theoretical plates of the refining tower is 15-50.

[0081] Preferably, the inlet of the material to be refined divides the refining tower into a distillation section and a stripping section, wherein the number of theoretical plates of the stripping section of the refining tower does not exceed 1 / 2 of the total theoretical plates (i.e., the inlet is set in the middle or lower middle part of the light removal tower), preferably 1 / 4-1 / 2.

[0082] In order to improve resource utilization and reduce overall production costs, according to a preferred embodiment of the present invention, the system may further include a solvent recovery tower and an optional intermediate product recovery device.

[0083] The material inlet and outlet of the solvent recovery tower include: an inlet for materials to be recovered, an outlet for recovery tower top logistics and an outlet for recovery tower bottom logistics, wherein the inlet for materials to be recovered is connected to the outlet for refining tower bottom logistics of the refining tower.

[0084] Preferably, the number of theoretical plates of the solvent recovery tower is 5-20. Usually, the inlet for the material to be recovered of the solvent recovery tower can be arranged near the middle. For example, the inlet for the material to be recovered can make the number of theoretical plates of the distillation section of the solvent recovery tower 2 / 5-3 / 5 of the total number of theoretical plates.

[0085] Preferably, the intermediate product recovery device is connected to the outlet of the recovery tower bottom stream. Preferably, the intermediate product recovery device contains a device for separating and recovering tetracyclododecene and / or dicyclopentadiene. Preferably, the intermediate product recovery device comprises: a distillation device and / or a depolymerization reaction distillation device.

[0086] 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.

[0087] 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 1-7, " / " represents not detected).

[0088] Example 1

[0089] use Figure 1 The system shown in the figure is used to separate and purify norbornene 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.

[0090] (1) Light removal: The norbornene synthesis liquid S-1 is introduced into the light removal tower T-1 for the first distillation to obtain the light removal tower top stream S-2 and the light removal tower bottom stream S-3.

[0091] The number of theoretical plates of the light-removal tower is 30, and the feed inlet of the norbornene synthesis liquid is arranged at the 10th theoretical plate from top to bottom.

[0092] The conditions of the first distillation include: tower top pressure 111 kPa, tower top temperature 91.8° C., tower bottom temperature 107.8° C., and reflux ratio 20.

[0093] (2) Refining: The light-removal tower bottom stream S-3 is introduced into the refining tower T-2 for a second distillation to obtain the refined tower top material S-4 and the refining tower bottom stream S-5.

[0094] The number of theoretical plates of the refining tower is 30, and the inlet for the material to be refined is set at the 20th theoretical plate from top to bottom.

[0095] The conditions of the second distillation include: top pressure 49 kPa, top temperature 70° C., bottom temperature 94.8° C., and reflux ratio 4.

[0096] (3) Solvent recovery: The refining tower bottom stream S-5 is introduced into the solvent recovery tower T-3 for the third distillation to obtain the recovery tower top stream S-6 and the recovery tower bottom stream S-7.

[0097] The number of theoretical plates of the solvent recovery tower is 10, and the inlet for the material to be recovered is set at the 5th theoretical plate from top to bottom.

[0098] The conditions of the third distillation include: top pressure 49 kPa, top temperature 87.7° C., bottom temperature 189.6° C., and reflux ratio 0.5.

[0099] The top stream of the light removal tower can be recovered and directly reused as a solvent in the preparation process of norbornene. The bottom stream of the recovery tower can be further processed to separate cyclopentadiene, tetracyclododecene and other components therein and reused in the preparation process of norbornene.

[0100] Table 1

[0101] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 10 1014 608 406 377 29 Cyclopentadiene / wt.% 0.04 4.06 3.3ppm 5.5ppm / / Toluene / wt.% 36.00 1.02 36.34 0.18 90.51 97.46 0.06 Norbornene / wt.% 60.95 94.91 60.62 99.82 1.90 2.05 1.2ppm Tetracyclododecene / wt.% 2.15 / 2.17 / 5.42 1.1ppm 75.92 Dicyclopentadiene / wt.% 0.58 / 0.59 / 1.46 0.49 14.14 Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.71 / 9.89

[0102] As can be seen from the data in Table 1, the logistics extracted from the top of the light removal tower is mainly norbornene, which can be recycled back to the reactor for use or partially extracted and partially recycled according to the situation. The purity of the norbornene product extracted from the top of the norbornene refining tower is 99.82%, containing 5.5ppm CPD. Toluene as a solvent should not affect the subsequent polymerization reaction of norbornene. Considering the subsequent application needs of norbornene, the top logistics of the refining tower can also be further processed to reduce the toluene content.

[0103] According to the calculation of the flow rate of the material flow, the yield of norbornene was 97.24% and the recovery rate of the solvent was 99.67%.

[0104] According to calculation, during the first distillation process, the norbornene entering the top stream of the light removal tower accounts for about 1.52 weight % of the total amount of norbornene in the synthetic liquid.

[0105] Example 2

[0106] The norbornene synthesis liquid used in this embodiment 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.

[0107] Using the method in Example 1, the conditions of controlling steps (1)-(3) are as follows:

[0108] The top pressure of the light removal tower is 111 kPa, the top temperature is 84.2 ° C, and the bottom temperature is 107.8 ° C; the top pressure of the refining tower is 49 kPa, the top temperature is 70 ° C, and the bottom temperature is 94.8 ° C; the top pressure of the solvent recovery tower is 49 kPa, the top temperature is 87.7 ° C, and the bottom temperature is 189.6 ° C; the other parameters and operation methods are the same as those in Example 1. The flow rate and composition of each step are shown in Table 2.

[0109] Table 2

[0110] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 10 1014 608 406 377 29 2-Methyl-1-butene 0.03 3.07 / / / / / Isoprene 0.01 1.02 / / / / / Cyclopentadiene / wt.% 0.04 4.07 2.6ppm 4.3ppm / / / Toluene / wt.% 36.00 0.95 36.35 0.18 90.50 97.46 0.06 Norbornene / wt.% 60.90 90.89 60.60 99.82 1.88 2.03 1.1ppm Tetracyclododecene / wt.% 2.15 / 2.17 / 5.42 1.1ppm 75.92 Dicyclopentadiene / wt.% 0.58 / 0.59 / 1.46 0.49 14.13 Tanrene 0.01 / 0.01 / 0.03 0.03 0.0096 Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.71 / 9.89

[0111] As can be seen from the data in Table 2, according to the method of the present invention, high-quality norbornene products can be obtained even when light components are contained in the synthetic liquid. The overhead stream of the light removal tower can be collected and centrally processed to recover cyclopentadiene and norbornene therein. The bottom stream of the solvent recovery tower can be collected and centrally processed to recover tetracyclododecene and dicyclopentadiene therein.

[0112] According to the calculation of the flow rate of the material flow, the yield of norbornene was 97.32% and the recovery rate of the solvent was 99.67%.

[0113] According to calculation, during the first distillation process, the norbornene entering the top stream of the light removal tower accounts for about 1.46 weight % of the total amount of norbornene in the synthetic liquid.

[0114] Example 3

[0115] Using the method in Example 2, the conditions of controlling steps (1)-(3) are as follows:

[0116] The number of theoretical plates of the light removal tower is 45, the feed port is located at the 20th theoretical plate from top to bottom, the tower top pressure is 80 kPa, the tower top temperature is 79 ° C, the tower bottom temperature is 96.9 ° C, and the reflux ratio is 10;

[0117] The theoretical plate number of the light-removal tower of the refining tower is 45, the feed port is located at the 30th theoretical plate from top to bottom, the tower top pressure is 80 kPa, the tower top temperature is 86.2 ° C, the tower bottom temperature is 109.3 ° C, and the reflux ratio is 4;

[0118] The number of theoretical plates of the solvent recovery tower is 18, the feed port is located at the 8th theoretical plate from top to bottom, the tower top pressure is 70 kPa, the tower top temperature is 99.4°C, the tower bottom temperature is 212.4°C, and the reflux ratio is 1. The remaining parameters are the same as those in Example 2. The flow rate and composition of each step are detailed in Table 3.

[0119] Table 3

[0120] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 21.10 1002.9 599.46 403.44 377 26.44 2-Methyl-1-butene 0.03 1.46 / / / / / Isoprene 0.01 0.49 / / / / / Cyclopentadiene / wt.% 0.04 1.93 2ppm 3.3ppm / / / Toluene / wt.% 36.00 0.01 36.76 0.03 91.33 97.74 / Norbornene / wt.% 60.90 96.11 60.16 99.97 1.00 1.07 / Tetracyclododecene / wt.% 2.15 / 2.20 / 5.46 / 83.26 Dicyclopentadiene / wt.% 0.58 / 0.59 / 1.47 1.16 5.90 Tanrene 0.01 / 0.01 / 0.03 0.03 0.4ppm Tricyclopentadiene / wt.% 0.28 / 0.29 / 0.71 / 10.84

[0121] From the data in Table 3, it can be seen that the method of this embodiment can also obtain high-quality norbornene products. The quality of norbornene products depends on the light removal tower and the refining tower, the norbornene yield depends on the norbornene taken away by the light removal tower top stream and the refining tower bottom stream, and the solvent recovery rate depends on the solvent taken away by the solvent recovery tower bottom stream.

[0122] According to the calculation of the flow rate of the material flow, the yield of norbornene was 96.10%, and the recovery rate of the solvent was 99.96%.

[0123] According to calculation, during the first distillation process, the norbornene entering the top stream of the light removal tower accounts for about 3.25 weight % of the total amount of norbornene in the synthetic liquid.

[0124] Example 4

[0125] The method in Example 3 is adopted, except that the conditions of controlling steps (1)-(3) are as follows:

[0126] The feed inlet of the light removal tower is located at the fifth theoretical plate from top to bottom, the reflux ratio is 30, the tower top pressure is 80 kPa, the tower top temperature is 67.8 ° C, the tower bottom temperature is 96.8 ° C, and the cyclopentadiene content in the tower bottom flow is controlled to be 1 ppm;

[0127] The content of norbornene in the refining tower bottom stream is 0.5%. The other parameters are the same as those in Example 1. The stream flow and composition of each step are shown in Table 4.

[0128] Table 4

[0129] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 6.74 1017.26 616.93 400.33 377 26.07 2-Methyl-1-butene 0.03 4.56 / / / / / Isoprene 0.01 1.52 / / / / / Cyclopentadiene / wt.% 0.04 6.06 1ppm 1.6ppm / / / Toluene / wt.% 36.00 5.73 36.20 0.14 91.78 97.45 / Norbornene / wt.% 60.90 82.13 60.76 99.86 0.50 0.53 / Tetracyclododecene / wt.% 2.15 / 2.16 / 5.50 0.41 87.71 Dicyclopentadiene / wt.% 0.58 / 0.58 / 1.48 1.58 / Tanrene 0.01 / 0.01 / 0.03 0.03 / Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.72 / 12.29

[0130] From the data in Table 4, it can be seen that the norbornene product obtained from the top of the refining tower has a very high purity and contains only 1.6 ppm of cyclopentadiene.

[0131] According to the calculation of the flow rate of the material flow, the yield of norbornene was 98.79% and the recovery rate of the solvent was 99.66%.

[0132] According to calculation, during the first distillation process, the norbornene entering the top stream of the light removal tower accounts for 0.89 weight % of the total amount of norbornene in the synthetic liquid.

[0133] Example 5

[0134] The method in Example 2 is adopted, except that the conditions of controlling steps (1)-(3) are as follows:

[0135] The number of theoretical plates of the light removal tower is 30, the feed port is located at the 10th theoretical plate from top to bottom, the tower top pressure is 50 kPa, the tower top temperature is 60.8 ° C, the tower bottom temperature is 82.9 ° C, and the reflux ratio is 20;

[0136] The number of theoretical plates of the refining tower is 30, the feed port is located at the 15th theoretical plate from top to bottom, the tower top pressure is 60 kPa, the tower top temperature is 76.5 ° C, the tower bottom temperature is 100.6 ° C, and the reflux ratio is 7;

[0137] The number of theoretical plates of the solvent recovery tower is 10, the feed port is located at the 5th theoretical plate from top to bottom, the tower top pressure is 30 kPa, the tower top temperature is 73.7 °C, the tower bottom temperature is 179.6 °C, and the reflux ratio is 0.5;

[0138] The remaining parameters are the same as those in Example 1. The flow rate and composition of each step are shown in Table 5.

[0139] Table 5

[0140] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 14.67 1009.33 608.19 401.14 377 26.44 2-Methyl-1-butene 0.03 2.09 / / / / / Isoprene 0.01 0.70 / / / / / Cyclopentadiene / wt.% 0.04 2.79 1ppm 1.7ppm / / / Toluene / wt.% 36.00 0.37 36.52 0.07 91.33 97.65 / Norbornene / wt.% 60.90 94.05 60.42 99.93 1.00 1.07 / Tetracyclododecene / wt.% 2.15 / 2.18 / 5.46 1.1ppm 84.36 Dicyclopentadiene / wt.% 0.58 / 0.59 / 1.47 1.25 4.64 Tanrene 0.01 / 0.01 / 0.03 0.03 / Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.71 / 10.99

[0141] From the data in Table 5, it can be seen that high-quality norbornene can be obtained in this embodiment. According to the calculation of the flow rate, the yield of norbornene is 97.14% and the solvent recovery rate is 99.86%. According to calculation, during the first distillation process, the norbornene entering the light-removal tower top flow accounts for 2.21% by weight of the total amount of norbornene in the synthetic liquid.

[0142] Comparative Example 1

[0143] The method in Example 5 was adopted, and the theoretical plate number, reflux ratio and feed position of the light removal tower and the refining tower were the same as those in Example 5, except that the top pressure of the light removal tower was increased to 150 kPa, resulting in the top temperature of the tower being increased to 95.6° C. and the bottom temperature of the tower being increased to 118.8° C. The other operating parameters and control indicators were the same as those in Example 5, and the flow rate and composition of the logistics in each step are detailed in Table 6.

[0144] Table 6

[0145] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 9.91 1014.09 611.11 402.98 377 25.98 2-Methyl-1-butene 0.03 3.10 / / / / / Isoprene 0.01 1.03 / / / / / Cyclopentadiene / wt.% 0.04 4.12 21ppm 34.8ppm / / / Toluene / wt.% 36.00 1.34 36.34 0.08 91.33 97.62 / Norbornene / wt.% 60.90 90.41 60.61 99.92 1.00 1.07 / Tetracyclododecene / wt.% 2.15 / 2.17 / 5.46 1.1ppm 84.76 Dicyclopentadiene / wt.% 0.58 18ppm 0.59 / 1.47 1.29 4.20 Tanrene 0.01 / 0.01 / 0.03 0.03 / Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.71 / 11.04

[0146] As can be seen from the data in Table 6, due to the high temperature of the tower body and the tower bottom of the light-removing tower, cyclopentadiene is dimerized in the tower body to generate dicyclopentadiene, and dicyclopentadiene is also slightly depolymerized, resulting in impurities in the tower top stream and the tower bottom stream, with the tower top stream containing 18ppm dicyclopentadiene and the tower bottom stream containing 21ppm cyclopentadiene. The cyclopentadiene in the tower top stream is brought into the norbornene product, making the cyclopentadiene content therein as high as 34.8ppm, which is difficult to meet the subsequent use requirements of cycloolefin copolymers.

[0147] Comparative Example 2

[0148] The method in Example 5 was adopted, and the theoretical plate number, reflux ratio and feed position of the lightness removal tower and the refining tower were the same as those in Example 5, except that the top pressure of the refining tower was increased to 130 kPa, resulting in the top temperature of the tower being increased to 104.1° C. and the bottom temperature of the tower being increased to 125.6° C. The other operating parameters and control indicators were the same as those in Example 5, and the flow rate and composition of the logistics in each step are detailed in Table 7.

[0149] Table 7

[0150] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 S-7 Logistics flow kg / h 1024 14.67 1009.33 610.90 398.43 377 26.44 2-Methyl-1-butene 0.03 2.09 / / / / / Isoprene 0.01 0.70 / / / / / Cyclopentadiene / wt.% 0.04 2.79 1ppm 37ppm 22ppm / / Toluene / wt.% 36.00 0.37 36.52 0.83 91.26 96.42 / Norbornene / wt.% 60.90 94.05 60.42 99.15 1.00 1.06 / Tetracyclododecene / wt.% 2.15 / 2.18 / 5.53 0.92 86.62 Dicyclopentadiene / wt.% 0.58 / 0.59 0.02 1.46 1.58 15ppm Tanrene 0.01 / 0.01 / 0.03 0.03 / Tricyclopentadiene / wt.% 0.28 / 0.28 / 0.72 / 13.38

[0151] From the data in Table 7, it can be seen that when the treatment conditions of the light-removal tower remain unchanged, the temperature of the refining tower body is generally higher due to the increase in the pressure at the top of the refining tower, causing cyclopentadiene to dimerize to form dicyclopentadiene. The higher temperature in the lower part and the bottom of the tower prompts dicyclopentadiene to depolymerize to form cyclopentadiene, resulting in the norbornene product at the top of the refining tower containing 37 ppm cyclopentadiene and 0.02% dicyclopentadiene, seriously affecting the product quality.

[0152] 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 norbornene, characterized in that: The method comprises: (1) Light removal: introducing the norbornene synthesis liquid into a light removal tower for first distillation to obtain a light removal tower top stream and a light removal tower bottom stream; (2) Purification: introducing the light-removal tower bottom stream obtained in step (1) into a purification tower for secondary distillation to obtain a purification tower top norbornene product stream and a purification tower bottom stream; The operating conditions of the first distillation are such that the bottom temperature of the tower does not exceed 110°C, and the operating conditions of the second 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 cyclopentadiene content in the light-removal tower bottom stream does not exceed 10 ppm, preferably does not exceed 3 ppm; and / or, in step (1), the conditions of the first distillation are such that the amount of norbornene entering the lightness removal tower top stream does not exceed 5% by weight, preferably does not exceed 3% by weight, of the norbornene in the synthetic liquid; Preferably, the conditions of the first distillation are such that the toluene content in the light-removal tower overhead stream does not exceed 6 wt%, preferably does not exceed 2 wt%.

3. The method according to claim 1 or 2, wherein: In step (1), the number of theoretical plates of the lightness removal tower is 15-50, and preferably the conditions of the first distillation include: the tower top pressure is 50-120 kPa, and the tower top temperature is 45-95° C.; Preferably, the conditions of the first distillation further include: the tower bottom temperature is 75-110°C; Preferably, the reflux ratio of the first distillation is 5-30, preferably 10-30.

4. The method according to claim 1, wherein: In step (2), the conditions of the second distillation are such that the content of norbornene in the refining tower bottom stream does not exceed 3% by weight, preferably does not exceed 2% by weight; And / or, in step (2), the conditions of the second distillation are such that the toluene content in the norbornene product stream does not exceed 1 wt%, preferably does not exceed 0.5 wt%, and more preferably does not exceed 0.2 wt%.

5. The method according to claim 1 or 4, wherein: In step (2), the number of theoretical plates of the refining tower is 15-50, and the conditions of the second distillation preferably include: the tower top pressure is 30-90 kPa, and the tower top temperature is 45-90° C.; Preferably, the conditions of the second distillation also include: the tower bottom temperature is 75-110°C; Preferably, the reflux ratio of the second distillation is 1.5-8.

6. The method according to any one of claims 1 to 5, wherein: The method further comprises: (3) Solvent recovery: introducing the refining tower bottom stream obtained in step (2) into a solvent recovery tower for third distillation to obtain a recovery tower top stream and a recovery tower bottom stream, and recycling the recovery tower top stream as a recovery solvent; Preferably, the conditions of the third distillation are such that the content of tetracyclododecene in the recovered tower top material does not exceed 0.1 wt %; Preferably, the conditions of the third distillation are such that the content of dicyclopentadiene in the recovered bottom stream does not exceed 15 wt %; Preferably, the method further comprises: (4) Recovery of intermediate products: Separating and recovering tetracyclododecene and / or dicyclopentadiene in the recovery tower bottom stream obtained in step (3), preferably, the separation method is selected from distillation and / or reactive distillation.

7. The method according to claim 6, wherein: The number of theoretical plates of the solvent recovery tower is 5-20, and the conditions of the third distillation preferably include: the tower top pressure is 30-80 kPa, and the tower top temperature is 55-110° C.; Preferably, the conditions of the third distillation further include: the tower bottom temperature is 150-230°C; Preferably, the reflux ratio of the third distillation is 0.2-3.

8. A system for separating and purifying norbornene, characterized in that: The system includes a lightness removal tower and a refining tower; The material inlets and outlets of the light-removal tower include: a norbornene synthesis liquid inlet, a light-removal tower top stream outlet, and a light-removal tower bottom stream outlet; The material inlets and outlets of the refining tower include: an inlet for materials to be refined, an outlet for the top of the refining tower and an outlet for the bottom of the refining tower; Among them, the outlet of the bottom logistics of the light removal tower is connected with the inlet of the material to be refined.

9. The system according to claim 8, wherein: The number of theoretical plates of the lightness removal tower is 15-50; Preferably, the inlet of the norbornene synthesis liquid divides the lightness removal tower into a distillation section and a stripping section, wherein the number of theoretical plates of the distillation section of the lightness removal tower does not exceed 1 / 2 of the total theoretical plates, preferably 1 / 10-1 / 2; And / or, the number of theoretical plates of the refining tower is 15-50; Preferably, the refining tower with a refined material inlet is divided into a distillation section and a stripping section, wherein the number of theoretical plates in the stripping section of the refining tower does not exceed 1 / 2 of the total theoretical plates, preferably 1 / 4-1 / 2.

10. The system according to claim 8 or 9, wherein: The system also includes a solvent recovery tower and an optional intermediate product recovery unit. The material inlet and outlet of the solvent recovery tower include: an inlet for materials to be recovered, an outlet for recovery tower top logistics and an outlet for recovery tower bottom logistics, wherein the inlet for materials to be recovered is connected to the outlet for refining tower bottom logistics of the refining tower; Preferably, the number of theoretical plates of the solvent recovery tower is 5-20; Preferably, the intermediate product recovery device is connected to the recovery tower bottom stream outlet, preferably the intermediate product recovery device contains a device for separating and recovering tetracyclododecene and / or dicyclopentadiene, and preferably the intermediate product recovery device includes: a distillation device and / or a depolymerization reaction distillation device.

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