Norbornene separation and purification method and system

Abstract

The invention relates to the field of separation and purification, and discloses a norbornene separation and purification method and system. The method provided by the invention is suitable for separation and purification of the norbornene synthesis liquid obtained by a solvent method, high-purity norbornene can be obtained in two steps, and meanwhile, a solvent which can be reused in a norbornene synthesis process can be directly obtained. According to the method, high-purity norbornene suitable for COC synthesis can be obtained at a high yield, and the method has the advantages of being short in technological process, high in resource utilization rate, reliable in process, easy to manage, easy to industrially popularize 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 norbornene. Background Art

[0002] Norbornene is an important comonomer for preparing cycloolefin copolymers (COC), which is usually prepared by Diels-Alder cycloaddition reaction of cyclopentadiene and ethylene under high temperature and high pressure conditions. In order to improve the performance of COC products (such as improving transparency, etc.), the purity of norbornene monomer is required to be high.

[0003] The process of synthesizing norbornene can be divided into two categories: solvent-based and solvent-free. The use of solvents can reduce heavy components and reduce coking and clogging of equipment, so most of the processes currently used in the industry are solvent-based processes. The norbornene synthesis liquid obtained by the solvent-based process has a complex composition, including solvents, unreacted raw materials, new components produced by the reaction, impurities brought in by the raw materials and their products, and impurities produced by side reactions. In addition, during the separation process, some impurities will be transformed into each other, resulting in difficulties in purifying high-purity norbornene, long process flow, high energy consumption during the treatment process, and high management difficulty. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the prior art in that the purification process of norbornene is long, the treatment method is complicated, and the yield and purity of the obtained norbornene still need to be improved, and to provide a method and system for separating and purifying norbornene. The method provided by the present invention has the advantages of a short process route, a simple and controllable treatment process, and is suitable for industrial promotion.

[0005] 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:

[0006] (1) introducing a norbornene synthesis liquid into a solvent separation tower for a first distillation, producing a separation tower top stream containing light components and norbornene from the tower top, producing a separation tower side stream from a tower side line gas phase production port, and producing a separation tower bottom stream containing heavy components from the tower bottom;

[0007] wherein the conditions of the first distillation are such that the toluene content in the separation tower overhead stream does not exceed 1% by weight, the norbornene content in the separation side stream does not exceed 3% by weight, and the toluene content in the separation tower bottom stream does not exceed 7% by weight;

[0008] (2) introducing the separation tower top stream obtained in step (1) into a norbornene refining tower for secondary distillation, and taking out a refined tower top stream containing light components from the tower top, and taking out a norbornene product from the tower bottom.

[0009] A second aspect of the present invention provides a system for separating and purifying norbornene, the system comprising:

[0010] Solvent separation tower: used to separate a separation tower top stream containing light components and norbornene from the norbornene synthesis liquid, a separation tower side stream, and to extract a separation tower bottom stream containing heavy components from the tower bottom; and

[0011] Norbornene refining tower: used to separate the refined tower top stream containing light components and the norbornene product from the separation tower top stream;

[0012] The material inlets and outlets of the solvent separation tower include: a norbornene synthesis liquid inlet, a separation tower top logistics outlet, a tower side line gas phase production outlet and a separation tower bottom logistics outlet;

[0013] The material inlets and outlets of the norbornene refining tower include: a separation tower top logistics inlet, a refining tower top logistics outlet and a norbornene product outlet;

[0014] Wherein, the separation tower top logistics outlet and the separation tower top logistics inlet are connected.

[0015] Through the above technical solution, at least the following beneficial effects can be obtained:

[0016] (1) The method provided by the present invention simplifies the purification process of norbornene synthesis liquid obtained by solvent synthesis, and the separation and purification process has low energy consumption, reliable process, convenient management, and is suitable for industrial-scale production and promotion.

[0017] (2) The method provided by the present invention has a high norbornene yield, and the obtained norbornene product has a high purity and is suitable for COC synthesis. 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: solvent separation tower; T-2: norbornene refining tower;

[0021] S-1: norbornene synthesis liquid; S-2: separation tower top logistics; S-3: separation side line logistics; S-4: separation tower bottom logistics; S-5: refining tower top logistics; S-6: norbornene product. 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 intermediates (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 generated by the conversion of raw materials or entrained in the raw materials (such as cyclopentadiene, isoprene, isoprene, etc.). ); “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 content of cyclopentadiene and dicyclopentadiene is not more than 15ppm, preferably not more than 10ppm, for example, it can be 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 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 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. Moreover, 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 norbornene synthesis liquid at one time when purifying and separating it, and it is easy to cause the problem that the purity of the norbornene product is insufficient and cannot meet the production needs.

[0028] The inventor of the present invention cleverly discovered during the research process that by coordinating the structural features of the distillation tower such as the theoretical plate number, inlet position and outlet position, the distillation conditions can be controlled, and the norbornene synthesis liquid can be directly separated into three parts: (tower top extraction) light component + norbornene, (tower side line extraction) toluene and (tower bottom extraction) heavy component, and then the light component can be further separated and removed to obtain norbornene. In the above method, by controlling the content of the solvent and heavy component entering the light component + norbornene logistics, the content of impurity components with a boiling point higher than norbornene in the obtained norbornene can be effectively controlled, thereby obtaining high-purity norbornene. The method only requires two steps to obtain high-purity norbornene, and can also separate and recover toluene in the synthetic liquid. It not only has the advantages of short process flow, low equipment investment, and high processing efficiency, but also can improve resource utilization and reduce waste.

[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) introducing a norbornene synthesis liquid into a solvent separation tower for a first distillation, producing a separation tower top stream containing light components and norbornene from the tower top, producing a separation tower side stream from a tower side line gas phase production port, and producing a separation tower bottom stream containing heavy components from the tower bottom;

[0031] wherein the conditions of the first distillation are such that the toluene content in the separation tower overhead stream does not exceed 1% by weight, the norbornene content in the separation side stream does not exceed 3% by weight, and the toluene content in the separation tower bottom stream does not exceed 7% by weight;

[0032] (2) introducing the separation tower top stream obtained in step (1) into a norbornene refining tower for secondary distillation, taking out a refining tower top stream containing light components from the tower top, and taking out a norbornene product from the tower bottom.

[0033] In the present invention, the purpose of step (1) is to separate the solvent separately while removing the solvent and heavy components from the norbornene synthesis liquid. The separated solvent is subsequently reused in the norbornene synthesis process, and the remaining part of the synthesis liquid from which the solvent and heavy components have been removed (i.e., the separation tower overhead stream) is further separated to obtain purified norbornene by separating the light components. In order to improve the purity of the norbornene product to meet the requirements of COC synthesis, the solvent and heavy components should be avoided as much as possible in step (1) to remain in the separation tower overhead stream.

[0034] According to a preferred embodiment of the present invention, in step (1), the conditions of the first distillation are such that the total content of toluene and heavy components (impurities) in the separation tower overhead stream does not exceed 0.5 wt%, preferably does not exceed 0.3 wt%, and more preferably does not exceed 0.1 wt%.

[0035] In order to reduce the loss of norbornene, the first distillation process should also prevent norbornene in the synthetic liquid from entering the separation side stream and the separation tower bottom stream. Preferably, the conditions of the first distillation are such that the content of norbornene in the separation side stream does not exceed 2.5 wt %. For example, it can be 2.5 wt %, 2.4 wt %, 2.3 wt %, 2.2 wt %, 2 wt %, 1.8 wt %, 1.5 wt %, 1.2 wt %, 1 wt %, 0.5 wt %, 0.1 wt %, 0, or any intermediate value between any of the above two values.

[0036] According to a preferred embodiment of the present invention, in step (1), the conditions of the first distillation are such that the content of toluene in the separation tower bottom stream does not exceed 5% by weight, for example, 5% by weight, 4.8% by weight, 4.5% by weight, 4.2% by weight, 4% by weight, 3.8% by weight, 3.5% by weight, 3.2% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0, or any intermediate value between any two of the above values.

[0037] Preferably, the conditions of the first distillation are such that the toluene content in the separation tower bottom stream does not exceed 3 wt%.

[0038] Preferably, the conditions of the first distillation are such that the content of norbornene in the separation tower bottom stream does not exceed 0.1 wt %. Preferably, it does not exceed 0.05 wt %. For example, it may be 0.05 wt %, 0.04 wt %, 0.03 wt %, 0.02 wt %, 0.01 wt %, 0.005 wt %, 0.001 wt %, 0.0005 wt %, 0.0001 wt %, 0, or any intermediate value between any of the above two values.

[0039] In order to make the component contents in each stream produced from the solvent separation tower meet the above requirements, according to a preferred embodiment of the present invention, in step (1), the number of theoretical plates of the solvent separation tower is 20-55. In order to reduce the norbornene and light component and heavy component impurities entering the separation side stream, the side stream gas phase production port of the tower is preferably located at the 2nd to 10th theoretical plate from bottom to top.

[0040] Dicyclopentadiene and tetracyclododecene can undergo depolymerization reaction at a higher temperature, and the depolymerization of dicyclopentadiene is cyclopentadiene, and the depolymerization of tetracyclododecene is cyclopentadiene and norbornene. Cyclopentadiene can react with the material containing carbon-carbon double bonds in the heavy component to produce Diels-alder diene synthesis reaction, which generates heavier components and easily causes equipment coking and blocking. Therefore, in order to reduce equipment coking, the operating conditions of decompression or normal pressure are preferably adopted in the solvent separation tower. In addition, for this purpose, it is also possible to consider controlling the tower bottom temperature in the solvent separation tower.

[0041] Preferably, the conditions of the first distillation include: tower top pressure 20-101 kPa, tower top temperature 45-100°C.

[0042] More preferably, the conditions of the first distillation include: tower top pressure 30-100 kPa, tower top temperature 50-95°C.

[0043] For example, the top pressure of the first distillation may be 30 kPa, 40 kPa, 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, or any intermediate value between any two of the above values.

[0044] For example, the top temperature of the first distillation tower can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or any intermediate value between any two of the above values.

[0045] Preferably, the conditions of the first distillation also include: a tower bottom temperature of 135-230°C, preferably 160-220°C.

[0046] For example, the bottom temperature of the first distillation can be 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, or any intermediate value between any two of the above values.

[0047] In order to ensure that the component contents in the various streams extracted from the solvent separation tower meet the aforementioned requirements, more preferably, the reflux ratio of the first distillation is 2-10, preferably 3-6.

[0048] According to a preferred embodiment of the present invention, the norbornene synthesis liquid can be fed near the middle of the solvent separation tower, for example, at 2 / 5 to 3 / 5 of the theoretical plate or filler from top to bottom.

[0049] In the present invention, the purpose of step (2) is to remove the light components in the separation tower overhead stream, thereby obtaining a norbornene product. In order to obtain a norbornene product that meets the requirements of COC synthesis, the light component impurities in the separation tower overhead stream should be removed as much as possible, and at the same time, it should be avoided that part of the light components are converted into heavy component impurities during the removal process to reduce the purity and quality of the norbornene product.

[0050] According to a preferred embodiment of the present invention, in step (2), the conditions of the second distillation are such that the content of cyclopentadiene in the norbornene product does not exceed 15 ppm, preferably does not exceed 10 ppm. For example, it can be 10 ppm, 8 ppm, 6 ppm, 4 ppm, 2 ppm, 1 ppm, 0.5 ppm, 0, or any intermediate value between any of the above two values.

[0051] In order to make the component contents in the refining tower top 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 norbornene refining tower is 15-50.

[0052] According to a preferred embodiment of the present invention, the second distillation is carried out under reduced pressure or normal pressure.

[0053] Preferably, the conditions for the second distillation include: a tower top pressure of 30-110 kPa and a tower top temperature of 45-100°C.

[0054] More preferably, the conditions of the second distillation include: a tower top pressure of 50-110 kPa, and a tower top temperature of 55-100°C.

[0055] For example, the top pressure of the second distillation may be 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 110 kPa, or any intermediate value between any two of the above values.

[0056] For example, the top temperature of the second distillation tower may be 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, or any intermediate value between any two of the above values.

[0057] In order to prevent light impurities from being converted into heavy impurities and entering the norbornene product, the bottom temperature of the second distillation should be controlled. Preferably, the conditions of the second distillation also include: the bottom temperature is 75-110°C, preferably 80-100°C.

[0058] For example, the bottom temperature of the second distillation column may be 80° C., 85° C., 90° C., 95° C., 100° C., or any intermediate value between the above two values.

[0059] In order to ensure that the component contents in the various streams extracted from the norbornene refining tower meet the aforementioned requirements, preferably, the reflux ratio of the second distillation is 10-25, preferably 10-20.

[0060] Considering that tetracyclododecene, dicyclopentadiene, etc. are also important raw materials for cycloolefin copolymers, therefore, in order to further improve the economic benefits of the method of the present invention, according to a preferred embodiment of the present invention, the method further comprises:

[0061] (3) Recovery of intermediate products: Separate and recover tetracyclododecene and / or dicyclopentadiene in the separation tower bottom stream obtained in step (1). Preferably, the separation method is selected from distillation and / or depolymerization reaction distillation.

[0062] Generally, in order to make the purity of the norbornene product extracted from the bottom of the refining tower high enough, a small amount of norbornene is allowed to enter the refining tower top stream and be extracted with the light component. In the refining tower top stream, the proportion of norbornene is usually large. In order to further improve the overall yield of norbornene, according to a preferred embodiment of the present invention, the method may also include the operation of separating and recovering norbornene from the refining tower top stream. Alternatively, (at least part of) the refining tower top stream may be recycled back to the solvent separation tower.

[0063] A second aspect of the present invention provides a system for separating and purifying norbornene, the system comprising:

[0064] Solvent separation tower: used to separate a separation tower top stream containing light components and norbornene from the norbornene synthesis liquid, separate a side stream, and extract a separation tower bottom stream containing heavy components from the bottom of the tower; and

[0065] Norbornene refining tower: used to separate the refined tower top stream containing light components and the norbornene product from the separation tower top stream;

[0066] The material inlets and outlets of the solvent separation tower include: a norbornene synthesis liquid inlet, a separation tower top logistics outlet, a tower side line gas phase production outlet and a separation tower bottom logistics outlet;

[0067] The material inlets and outlets of the norbornene refining tower include: a separation tower top logistics inlet, a refining tower top logistics outlet and a norbornene product outlet;

[0068] The separation tower top logistics outlet and the separation tower top logistics inlet are connected.

[0069] According to a preferred embodiment of the present invention, the number of theoretical plates of the solvent separation tower is 20-55, and the gas phase extraction port is preferably located at the 2nd to 10th theoretical plate from bottom to top.

[0070] Preferably, the inlet of the norbornene synthesis liquid divides the solvent separation tower into a distillation section and a stripping section, wherein the number of theoretical plates in the distillation section is 2 / 5-3 / 5 of the total number of theoretical plates.

[0071] Preferably, the number of theoretical plates between the norbornene synthesis liquid inlet and the tower side line gas phase production port of the solvent separation tower is 30-55% of the total number of theoretical plates. For example, for the solvent separation tower with 20-55 theoretical plates in the present invention, the number of theoretical plates between the norbornene synthesis liquid inlet and the tower side line gas phase production port can be 10-30, preferably 15-20.

[0072] According to a preferred embodiment of the present invention, the number of theoretical plates of the norbornene refining tower is 15-50.

[0073] Preferably, the top stream inlet of the separation tower divides the norbornene refining tower into a rectification section and a stripping section, wherein the number of theoretical plates of the rectification section is 2 / 5-3 / 4 of the total number of theoretical plates, preferably 2 / 5-2 / 3.

[0074] According to a preferred embodiment of the present invention, the system further comprises a material recovery unit, and the material recovery unit comprises an optional toluene recovery device and an intermediate product recovery device.

[0075] Preferably, the optional toluene recovery device is connected to the side line gas phase outlet of the solvent separation tower.

[0076] Preferably, the intermediate product recovery device is connected to the separation tower bottom stream outlet of the solvent separation tower, and preferably the intermediate product recovery device comprises a distillation device and / or a reactive distillation device for separating and recovering dicyclopentadiene and / or tetracyclododecene.

[0077] According to some preferred embodiments of the present invention, the material recovery unit may further include a norbornene separation and recovery device, which is connected to the outlet of the top stream of the refining tower of the norbornene refining tower, and is used to separate and recover norbornene from the top stream of the refining tower, thereby obtaining a higher overall yield.

[0078] According to other preferred embodiments of the present invention, the outlet of the refining tower top stream can be connected to the inlet of the norbornene synthesis liquid of the solvent separation tower, so that the refining tower top stream is circulated back to the solvent separation tower to improve the overall yield of norbornene. When the outlet of the refining tower top stream is connected to the inlet of the norbornene synthesis liquid, a diverter device can be provided between the two, or multiple (for example, two) outlets of the refining tower top stream can be provided, so as to realize the reuse of part of the refining tower top stream and the extraction (discharge or collection) of the other part.

[0079] 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.

[0080] 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 1-8, " / " represents not detected).

[0081] Example 1

[0082] 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.

[0083] (1) The norbornene synthesis liquid S-1 is fed into a solvent separation tower T-1 for the first distillation, and a separation tower top stream S-2 containing light components and norbornene is produced from the top of the tower, a separation tower side stream S-3 is produced from the tower side line gas phase production port, and a separation tower bottom stream S-4 containing heavy components is produced from the bottom of the tower.

[0084] The number of theoretical plates of the solvent separation tower T-1 is 35, the feed position is at the 17th theoretical plate from top to bottom, and the side line outlet is located at the 33rd theoretical plate from top to bottom.

[0085] The conditions of the first distillation include: top pressure 50 kPa, top temperature 70.5° C., bottom temperature 179.5° C., and reflux ratio 4.

[0086] The separated side stream can be collected and reused in the norbornene synthesis process; the bottom stream S-4 can be further processed to separate components such as dicyclopentadiene and tetracyclododecene and reused in the norbornene synthesis process.

[0087] (2) The overhead stream S-2 obtained in step (1) is introduced into a norbornene refining tower for secondary distillation, and a refined overhead stream S-5 is produced from the top of the tower, and a bottom stream S-6 containing norbornene is produced from the bottom of the tower.

[0088] The number of theoretical plates of the norbornene refining tower is 30, and the feed position is at the 20th theoretical plate from top to bottom.

[0089] The conditions of the second distillation include: tower top pressure 110 kPa, tower top temperature 92.6° C., tower bottom temperature 100.8° C., and reflux ratio 25.

[0090] Table 1

[0091] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 616.00 382.00 26.00 12.89 603.12 Cyclopentadiene / wt.% 0.04 0.0665 / / 3.17 1ppm Toluene / wt.% 36.00 0.10 96.10 3.55 0.2ppm 0.10 Norbornene / wt.% 60.95 99.83 2.39 0.03 96.83 99.90 Tetracyclododecene / wt.% 2.15 / 0.23 81.37 / / Dicyclopentadiene / wt.% 0.58 / 1.28 4.03 / / Tricyclopentadiene / wt.% 0.28 / 6.7ppm 11.02 / /

[0092] It can be seen from the data in Table 1 that the logistics extracted from the side line of the solvent separation tower is mainly toluene, which can be recycled back to the reactor for use, and the content of heavy components such as tetracyclododecene is very small, and even if it is recycled, it will not increase the coking of the equipment; the main component of the logistics extracted from the bottom of the solvent separation tower is tetracyclododecene, and also includes part of dicyclopentadiene. After further separation, the components such as tetracyclododecene and dicyclopentadiene can be recovered and reused in the norbornene synthesis process to improve resource utilization.

[0093] The norbornene product extracted from the bottom of the norbornene refining tower has a purity of 99.90%, and the main impurity is toluene (which, as a solvent, does not affect the subsequent polymerization reaction of norbornene). It only contains 1ppm of cyclopentadiene, which can meet the needs of COC synthesis.

[0094] According to the calculation of the flow rate of the material flow, the yield of norbornene was 96.54% and the recovery rate of the solvent was 99.58%.

[0095] Example 2

[0096] 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. The method in Example 1 is adopted, except that the top temperature of the second distillation is adjusted to 86.1°C. The remaining operations and conditions are the same as in Example 1. The flow rate and composition of each step are detailed in Table 2.

[0097] Table 2

[0098] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 616.00 382.00 26.00 12.50 603.50 2-Methyl-1-butene / wt.% 0.03 0.0499 / / 2.46 / Isoprene / wt.% 0.01 0.0166 / / 0.82 / Cyclopentadiene / wt.% 0.04 0.0665 / / 3.27 1ppm Toluene / wt.% 36.00 0.10 96.10 3.54 0.2ppm 0.10 Norbornene / wt.% 60.90 99.83 2.37 0.03 93.45 99.90 Tetracyclododecene / wt.% 2.15 / 0.23 81.37 / / Dicyclopentadiene / wt.% 0.58 / 1.28 4.03 / / Tanrene / wt.% 0.01 / 0.03 0.0152 / / Tricyclopentadiene / wt.% 0.28 / 6.7ppm 11.02 / /

[0099] By comparing the data in Table 1 and Table 2, it can be seen that when there are more light components in the synthetic liquid, by controlling the top temperature of the norbornene refining tower, a norbornene product that meets the needs of COC synthesis can still be obtained.

[0100] Example 3

[0101] The method in Example 2 is adopted, except that the distillation conditions are controlled in the following manner:

[0102] Solvent separation tower: top pressure 30 kPa, top temperature 55.1 °C, reflux ratio 6, bottom temperature 166.2 °C;

[0103] Norbornene refining tower: tower top pressure 80kPa, tower top temperature 74.8°C, tower bottom temperature 90.2°C, reflux ratio 15, and the cyclopentadiene content in the norbornene product in the tower bottom flow is 5ppm.

[0104] The remaining operations and conditions are the same as those in Example 2. The flow rate and composition of each step are detailed in Table 3.

[0105] Table 3

[0106] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 616.00 382.00 26.00 12.53 603.50 2-Methyl-1-butene / wt.% 0.03 0.0499 / / 2.45 / Isoprene / wt.% 0.01 0.0166 / / 0.82 / Cyclopentadiene / wt.% 0.04 0.0665 / / 3.25 5ppm Toluene / wt.% 36.00 0.0065 96.30 2.83 / 66ppm Norbornene / wt.% 60.90 99.86 2.22 0.02 93.49 99.99 Tetracyclododecene / wt.% 2.15 / 0.17 82.11 / / Dicyclopentadiene / wt.% 0.58 / 1.28 4.00 / / Tanrene / wt.% 0.01 / 0.03 0.0145 / / Tricyclopentadiene / wt.% 0.28 / 3.7ppm 11.02 / /

[0107] It can be seen from the data in Table 3 that reducing the operating pressure at the top of the solvent separation tower can reduce the tower bottom temperature. Reducing the pressure at the top of the norbornene refining tower can reduce the temperature of the distillation tower, especially the tower bottom temperature, which can reduce the dimerization reaction of cyclopentadiene in the tower to form dicyclopentadiene, and also reduce the toluene content in the product, further improving the quality of the product.

[0108] Example 4

[0109] The method in Example 2 is adopted, except that the distillation conditions are controlled as follows:

[0110] Solvent separation tower: top pressure 100 kPa, top temperature 93.8 °C, reflux ratio 8, bottom temperature 201.7 °C;

[0111] Norbornene refining tower: tower top pressure 50kPa, tower top temperature 62.3°C, tower bottom temperature 76.4°C, reflux ratio 15, and the cyclopentadiene content in the norbornene product in the tower bottom flow is 10ppm.

[0112] The remaining operations and conditions are the same as those in Example 2. The flow rate and composition of each step are detailed in Table 4.

[0113] Table 4

[0114] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 616.00 382.00 26.00 17.77 598.23 2-Methyl-1-butene / wt.% 0.03 0.0499 / / 1.73 / Isoprene / wt.% 0.01 0.0166 / / 0.58 / Cyclopentadiene / wt.% 0.04 0.0665 0.03 0.02 2.27 10ppm Toluene / wt.% 36.00 0.07 96.06 4.86 / 0.07 Norbornene / wt.% 60.90 99.80 2.32 0.04 95.42 99.93 Tetracyclododecene / wt.% 2.15 / 0.31 80.09 / / Dicyclopentadiene / wt.% 0.58 / 1.25 3.96 / / Tanrene / wt.% 0.01 / 0.03 0.0161 / / Tricyclopentadiene / wt.% 0.28 / 9.3ppm 11.01 / /

[0115] Although the pressure of the solvent separation tower is high and the tower bottom temperature reaches 201.7°C, resulting in a cyclopentadiene content of 0.02% in the tower bottom stream, it was found that the tower body temperature at the side line outlet was 117.3°C, and the tower body gradually decreased. It can be seen from the data in Table 4 that under the above treatment conditions, no obvious cyclopentadiene dimerization reaction was caused to make the dicyclopentadiene content in the tower top stream unqualified. At the same time, reducing the operating pressure of the norbornene refining tower is conducive to reducing the operating temperature of the tower, and thus still obtaining norbornene products that meet the quality requirements.

[0116] Example 5

[0117] use Figure 1 The system shown in FIG. 1 is used to separate norbornene from the norbornene synthesis liquid in the following manner. The norbornene synthesis liquid used in this embodiment is the same as that in Example 2. The flow rate and composition of each step are detailed in Table 5.

[0118] (1) The norbornene synthesis liquid S-1 is fed into a solvent separation tower T-1 for the first distillation, and a separation tower top stream S-2 containing light components and norbornene is produced from the top of the tower, a separation tower side stream S-3 is produced from the tower side line gas phase production port, and a separation tower bottom stream S-4 containing heavy components is produced from the bottom of the tower.

[0119] The number of theoretical plates of the solvent separation tower T-1 is 50, the feed position is at the 20th theoretical plate from top to bottom, and the side line outlet is located at the 45th theoretical plate from top to bottom.

[0120] The conditions of the first distillation include: tower top pressure 80 kPa, tower top temperature 85.9° C., tower bottom temperature 218.8° C., and reflux ratio 5.

[0121] The separated side stream can be collected and reused in the norbornene synthesis process; the bottom stream S-4 can be further processed to separate components such as dicyclopentadiene and tetracyclododecene and reused in the norbornene synthesis process.

[0122] (2) The overhead stream S-2 obtained in step (1) is introduced into a norbornene refining tower for secondary distillation, and a refined overhead stream S-5 is produced from the top of the tower, and a bottom stream S-6 containing norbornene is produced from the bottom of the tower.

[0123] The number of theoretical plates of the norbornene refining tower is 45, and the feed position is at the 20th theoretical plate from top to bottom.

[0124] The conditions of the second distillation include: tower top pressure 60 kPa, tower top temperature 68.5° C., tower bottom temperature 81.5° C., and reflux ratio 10.

[0125] Table 5

[0126] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 616.00 382.00 26.00 18.69 597.31 2-Methyl-1-butene / wt.% 0.03 0.0499 / / 1.64 / Isoprene / wt.% 0.01 0.0166 / / 0.55 / Cyclopentadiene / wt.% 0.04 0.0665 0.03 / 2.16 10ppm Toluene / wt.% 36.00 0.0078 96.48 0.10 / 0.0081 Norbornene / wt.% 60.90 99.86 2.22 3.1ppm 95.65 99.99 Tetracyclododecene / wt.% 2.15 / 0.02 84.39 / / Dicyclopentadiene / wt.% 0.58 / 1.25 4.49 / / Tanrene / wt.% 0.01 / 0.03 0.0040 / / Tricyclopentadiene / wt.% 0.28 / 3.3ppm 11.02 / /

[0127] By comparing the data in Table 2 and Table 5, it can be seen that the separation purpose of the present invention can be achieved by adjusting the operating conditions under different conditions such as the theoretical plate number, feed position and side line outlet position of the two distillation towers. For example, when the theoretical plate number increases, appropriately reducing the reflux ratio of the norbornene refining tower can reduce the cyclopentadiene content in the norbornene product to meet the COC synthesis requirements.

[0128] Example 6

[0129] use Figure 1 The system shown in FIG. 1 is used to separate norbornene from the norbornene synthesis liquid in the following manner. The norbornene synthesis liquid used in this embodiment is the same as that in Example 2. The flow rate and composition of each step are detailed in Table 6.

[0130] (1) The norbornene synthesis liquid S-1 is fed into a solvent separation tower T-1 for the first distillation, and a separation tower top stream S-2 containing light components and norbornene is produced from the top of the tower, a separation tower side stream S-3 is produced from the tower side line gas phase production port, and a separation tower bottom stream S-4 containing heavy components is produced from the bottom of the tower.

[0131] The number of theoretical plates of the solvent separation tower T-1 is 40, the feed position is at the 22nd theoretical plate from top to bottom, and the side line outlet is located at the 37th theoretical plate from top to bottom.

[0132] The conditions of the first distillation include: tower top pressure 60 kPa, tower top temperature 76.4° C., tower bottom temperature 217.2° C., and reflux ratio 5.

[0133] The separated side stream can be collected and reused in the norbornene synthesis process; the bottom stream S-4 can be further processed to separate components such as dicyclopentadiene and tetracyclododecene and reused in the norbornene synthesis process.

[0134] (2) The overhead stream S-2 obtained in step (1) is introduced into a norbornene refining tower for secondary distillation, and a refined overhead stream S-5 is produced from the top of the tower, and a bottom stream S-6 containing norbornene is produced from the bottom of the tower.

[0135] The number of theoretical plates of the norbornene refining tower is 20, and the feed position is at the 10th theoretical plate from top to bottom.

[0136] The conditions of the second distillation include: top pressure 60 kPa, top temperature 67.5° C., bottom temperature 81.6° C., and reflux ratio 20.

[0137] Table 6

[0138]

[0139]

[0140] By comparing the data in Table 2 and Table 6, it can be seen that the separation purpose of the present invention can be achieved by adjusting the operating conditions under different conditions such as the theoretical plate number, feed position and side line outlet position of the two distillation towers. For example, when the theoretical plate number is reduced, appropriately increasing the reflux ratio of the norbornene refining tower can reduce the cyclopentadiene content in the norbornene product to meet the COC synthesis requirements.

[0141] Example 7

[0142] The method in Example 6 is adopted, except that the distillation conditions are controlled as follows:

[0143] The processing conditions of the solvent separation tower are exactly the same as those in Example 6;

[0144] Norbornene refining tower: the number of theoretical plates is 30, the feed position is the 20th plate, the tower top pressure is 180 kPa, the tower top temperature is 108.1° C., the tower bottom temperature is 119.3° C., and the reflux ratio is 20. The remaining operations and conditions are the same as those in Example 6. The flow rate and composition of each step are detailed in Table 7.

[0145] Table 7

[0146] Component Logistics S-5 S-6 Logistics flow kg / h 16.98 613.02 2-Methyl-1-butene / wt.% 1.81 / Isoprene / wt.% 0.60 / Cyclopentadiene / wt.% 2.41 11ppm Toluene / wt.% 7.5ppm 1.00 Norbornene / wt.% 95.01 99.00 Tetracyclododecene / wt.% / / Dicyclopentadiene / wt.% 4ppm 25ppm Tanrene / wt.% / / Tricyclopentadiene / wt.% / /

[0147] It can be seen from the data in Table 7 that due to the high operating pressure of the norbornene refining tower, the operating temperature is high, and cyclopentadiene undergoes dimerization reaction in the tower body to form dicyclopentadiene, resulting in a high content of cyclopentadiene and dicyclopentadiene in the bottom flow, which is difficult to meet the requirements for use as a raw material for cycloolefin copolymer COC.

[0148] Example 8

[0149] The method in Example 2 was adopted, except that the overhead flow rate of the solvent separation tower and the side line extraction flow rate of the tower were adjusted. The remaining operations and conditions were the same as those in Example 2. The flow rate and composition of each step are shown in Table 8.

[0150] Table 8

[0151] Component Logistics S-1 S-2 S-3 S-4 S-5 S-6 Logistics flow kg / h 1024 626.00 372.00 26.00 12.66 613.35 2-Methyl-1-butene / wt.% 0.03 0.0491 / / 2.43 / Isoprene / wt.% 0.01 0.0164 / / 0.81 / Cyclopentadiene / wt.% 0.04 0.0654 / / 3.23 1ppm Toluene / wt.% 36.00 0.41 98.15 3.55 0.7ppm 0.42 Norbornene / wt.% 60.90 99.45 0.28 0.0031 93.53 99.58 Tetracyclododecene / wt.% 2.15 / 0.23 81.37 / / Dicyclopentadiene / wt.% 0.58 / 1.31 4.04 / / Tanrene / wt.% 0.01 / 0.03 0.0153 / / Tricyclopentadiene / wt.% 0.28 / 6.9ppm 11.02 / /

[0152] By comparing the data in Table 2 and Table 8, it can be seen that, under the condition that other conditions remain unchanged, the purification purpose of the present invention can also be achieved by changing the solvent separation tower overhead flow and the tower side line extraction flow. Usually, the overhead flow can be adjusted according to the composition of the material, but if the overhead extraction amount is large, part of the toluene will be carried into the refining tower and then into the norbornene product. If it is necessary to control the toluene content in the product, the overhead extraction amount of the solvent separation tower can be appropriately reduced (for example, it can also be adjusted in accordance with the conditions such as the reflux ratio or the theoretical plate number of the tower).

[0153] 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) introducing a norbornene synthesis liquid into a solvent separation tower for a first distillation, producing a separation tower top stream containing light components and norbornene from the tower top, producing a separation tower side stream from a tower side line gas phase production port, and producing a separation tower bottom stream containing heavy components from the tower bottom; wherein the conditions of the first distillation are such that the toluene content in the separation tower overhead stream does not exceed 1% by weight, the norbornene content in the separation side stream does not exceed 3% by weight, and the toluene content in the separation tower bottom stream does not exceed 7% by weight; (2) introducing the separation tower top stream obtained in step (1) into a norbornene refining tower for secondary distillation, taking out a refining tower top stream containing light components from the tower top, and taking out a norbornene product from the tower bottom.

2. The method according to claim 1, wherein: In step (1), the conditions of the first distillation are such that the total content of toluene and heavy components in the separation tower overhead stream does not exceed 0.5 wt %; and / or, in step (1), the conditions of the first distillation are such that the norbornene content in the separated side stream does not exceed 2.5 wt %; And / or, in step (1), the conditions of the first distillation are such that the content of toluene in the separation tower bottom stream does not exceed 5% by weight, preferably does not exceed 3% by weight.

3. The method according to claim 1 or 2, wherein: In step (1), the number of theoretical plates of the solvent separation tower is 20-55, and the side line gas phase extraction port of the tower is preferably located at the 2nd to 10th theoretical plate from bottom to top; Preferably, the conditions of the first distillation include: tower top pressure 20-101 kPa, tower top temperature 45-100°C; More preferably, the conditions of the first distillation further include: a tower bottom temperature of 135-230°C, preferably 160-220°C; More preferably, the reflux ratio of the first distillation is 2-10, preferably 3-6.

4. The method according to claim 1, wherein: In step (2), the conditions of the second distillation are such that the cyclopentadiene content in the norbornene product does not exceed 15 ppm, preferably does not exceed 10 ppm.

5. The method according to claim 1 or 4, wherein: In step (2), the number of theoretical plates of the norbornene refining tower is 15-50, and the conditions of the second distillation preferably include: tower top pressure 30-110 kPa, tower top temperature 45-100° C.; Preferably, the conditions of the second distillation further include: a tower bottom temperature of 75-110°C, preferably 80-100°C; Preferably, the reflux ratio of the second distillation is 10-25, preferably 10-20.

6. The method according to any one of claims 1 to 5, wherein: The method further comprises: (3) intermediate product recovery: separating and recovering tetracyclododecene and / or dicyclopentadiene in the bottom stream of the solvent separation tower obtained in step (1), preferably, the separation method is selected from distillation and / or depolymerization reaction distillation; And / or, the method further comprises the operation of separating and recovering norbornene from the refining tower top stream.

7. A system for separating and purifying norbornene, characterized in that: The system comprises: Solvent separation tower: used to separate a separation tower top stream containing light components and norbornene from the norbornene synthesis liquid, a separation tower side stream, and to extract a separation tower bottom stream containing heavy components from the tower bottom; and Norbornene refining tower: used to separate the refined tower top stream containing light components and the norbornene product from the separation tower top stream; The material inlets and outlets of the solvent separation tower include: a norbornene synthesis liquid inlet, a separation tower top logistics outlet, a tower side line gas phase production outlet and a separation tower bottom logistics outlet; The material inlets and outlets of the norbornene refining tower include: a separation tower top logistics inlet, a refining tower top logistics outlet and a norbornene product outlet; Wherein, the separation tower top logistics outlet and the separation tower top logistics inlet are connected.

8. The system according to claim 7, wherein: The number of theoretical plates of the solvent separation tower is 20-55, and the side line gas phase extraction port is preferably located at the 2nd to 10th theoretical plate from bottom to top; Preferably, the inlet of the norbornene synthesis liquid divides the solvent separation tower into a rectification section and a stripping section, wherein the number of theoretical plates in the rectification section is 2 / 5-3 / 5 of the total number of theoretical plates; Preferably, the number of theoretical plates between the norbornene synthesis liquid inlet and the side gas phase extraction outlet of the solvent separation tower is 30-55% of the total number of theoretical plates.

9. The system according to claim 7, wherein: The number of theoretical plates of the norbornene refining tower is 15-50; Preferably, the top stream inlet of the separation tower divides the norbornene refining tower into a rectification section and a stripping section, wherein the number of theoretical plates of the rectification section is 2 / 5-3 / 4 of the total number of theoretical plates.

10. The system according to any one of claims 7 to 9, wherein: The system further comprises a material recovery unit, wherein the material recovery unit comprises an optional toluene recovery device and an intermediate product recovery device; Preferably, the optional toluene recovery device is connected to the side line gas phase extraction port of the solvent separation tower; Preferably, the intermediate product recovery device is connected to the separation tower bottom stream outlet of the solvent separation tower, and preferably the intermediate product recovery device comprises a distillation device and / or a reactive distillation device for separating and recovering dicyclopentadiene and / or tetracyclododecene.

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