Method for preparing tetracyclododecene through reactive distillation

Abstract

The invention provides a method for preparing tetracyclododecene in a reactive distillation device by taking C9 fraction and norbornene as raw materials. The method comprises the following steps: mixing the C9 fraction and the norbornene in a mixer and reacting in the reactive distillation device; the reacted material is directly rectified in a reaction rectification device, residual C9 fraction and norbornene in the reaction are obtained at the tower top, and a crude tetracyclododecene product is obtained in the reaction kettle; and separating high-boiling-point components from the crude tetracyclododecene product in the reaction kettle section of the rectifying tower in the reactive distillation device in a third rectifying tower to obtain the high-purity tetracyclododecene product. According to the invention, the reaction rectification device is used, and the reactor is combined with the rectification tower, so that the reaction product can be directly and preliminarily separated to obtain a light component mainly containing norbornene and a heavy component containing tetracyclododecene, the equipment cost can be saved, the energy consumption can be reduced, and the rectification effect can be improved; meanwhile, the C9 fraction is used as a raw material, and downstream application of the C9 fraction is expanded.

Description

Technical Field

[0001] The present invention belongs to the field of downstream applications of C9 fractions and the synthesis of cyclotetradecene, and relates to a method for preparing cyclotetradecene from C9 fractions and norbornene as raw materials in a reactive distillation apparatus. Background Art

[0002] C9 fractions are by-products of olefin plant cracking, which contain a large amount of dicyclopentadiene. Due to the complex composition of C9 fractions, the boiling points of a large number of components are close to each other, making it difficult to separate. Therefore, the downstream applications of C9 fractions are few. In the early days, C9 fractions were mostly directly used as fuels in industry, resulting in a great waste of resources. Although in recent years, some enterprises have used C9 fractions to produce resins or extract dicyclopentadiene by cracking followed by rectification and then polymerization, the added value of their products is not high.

[0003] Cyclotetradecene is a cycloolefin monomer, which is prepared by the Diels-Alder reaction of cyclopentadiene and norbornene, and is one of the important raw materials for cycloolefin copolymers (COC). COC has characteristics such as high transparency, heat resistance, chemical stability, and moisture resistance, so it has a wide range of applications in the fields of packaging, medical treatment, optics, and intelligent devices. Currently, norbornene is mostly used as the cycloolefin monomer in the preparation of COC. Research shows that if a cycloolefin monomer with a larger steric hindrance is used, COC can have a higher glass transition temperature and stronger toughness at a lower cycloolefin insertion rate. The COC products synthesized by Mitsui Chemicals in Japan using cyclotetradecene as the cycloolefin monomer have better optical properties and wider applications compared to other COCs.

[0004] Patent JP2008247850A mentions a process for preparing cyclotetradecene from ethylene, norbornene, and dicyclopentadiene, and a high-purity cyclotetradecene product is obtained by rectification. Patent US6441259B1 introduces a method for preparing cyclotetradecene using crude dicyclopentadiene as the raw material. Patent CN112592248A mentions a process for preparing cyclotetradecene from norbornene and dicyclopentadiene as raw materials.

[0005] In summary, it can be seen that if the dicyclopentadiene existing in the C9 fraction can react with norbornene to prepare cyclotetradecene, and then produce COC products with high added value, the utilization value of the C9 fraction can be greatly improved. Summary of the Invention

[0006] Aiming at the problem of difficult downstream applications of C9 fractions used in the above-mentioned existing technologies, the present invention provides a method for preparing cyclotetradecene from C9 fractions and norbornene as raw materials in a reactive distillation apparatus, and a high-purity cyclotetradecene product can be prepared.

[0007] The method for preparing tetracyclododecene from C9 fraction and norbornene as raw materials in a reactive distillation unit provided by the present invention comprises the following steps:

[0008] S1: Mix the C9 fraction and norbornene in a mixer, and then heat and react the mixed material in the reaction kettle of the reactive distillation unit. Dicyclopentadiene in the C9 fraction cracks into cyclopentadiene at high temperature and reacts with a large amount of norbornene around to generate tetracyclododecene;

[0009] S2: Directly distill the reacted material in the reactive distillation unit. The unreacted C9 fraction and norbornene are obtained at the top of the distillation column section, and the crude product of tetracyclododecene is obtained in the reaction kettle section of the distillation column;

[0010] S3: Remove the light components and heavy components from the top product of the distillation column section in the reactive distillation unit through two-stage distillation to obtain norbornene and send it back to the mixer;

[0011] S4: Separate the high-boiling components from the crude product of tetracyclododecene in the reaction kettle section of the distillation column in the reactive distillation unit to obtain a high-purity tetracyclododecene product.

[0012] Preferably, in step S1, the mass content of norbornene is ≥99%; the mass content of dicyclopentadiene in the C9 raw material is ≥30%; the rotation speed of the mixer is 500 - 2200 r / min, and the stirring time is 10 - 90 min; the molar ratio of norbornene added in the mixer to dicyclopentadiene in the C9 raw material is (10 - 25):1; the reaction temperature for the heating reaction is 150°C - 250°C, the reaction time is 10 min - 120 min, and the pressure in the reaction kettle is 0.1 - 0.5 MPa.

[0013] Preferably, in step S1, the reacted material is directly distilled in the reactive distillation unit.

[0014] Preferably, in step S2, the distillation is atmospheric distillation, and the temperature is 120°C - 150°C; the unreacted C9 fraction and norbornene obtained at the top of the reactive distillation unit are sent to the first distillation column, and the material in the reaction kettle of the reactive distillation unit is sent to the third distillation column.

[0015] Preferably, in step S3, the first distillation column is atmospheric distillation, the top temperature is 65°C - 75°C, and the bottom temperature is 80°C - 95°C; the light components with lower boiling points in the C9 fraction are separated at the top of the first distillation column, and the bottom material is sent to the second distillation column. The second distillation column is atmospheric distillation, the top temperature is 95°C - 110°C, and the bottom temperature is 120°C - 135°C; the unreacted norbornene obtained at the top of the second distillation column is returned to the mixer, and the heavy components with higher boiling points in the C9 fraction are separated at the bottom.

[0016] Preferably, in step S4, the third rectification column is a vacuum rectification column. The top pressure is set to 0.2 - 0.6 kPa, the top temperature is set to 65 - 135 °C, the bottom pressure is set to 1 - 15 kPa, and the bottom temperature is set to 90 - 160 °C. A high-purity tetracyclododecene product is obtained at the top of the third rectification column, and high-boiling by-products are separated at the bottom of the column.

[0017] Compared with the prior art, the technical effects of the present invention are as follows:

[0018] (1) Using the C9 fraction as the source of dicyclopentadiene in the raw materials for preparing tetracyclododecene not only reduces the raw material cost but also expands the downstream applications of C9.

[0019] (2) By using a reactive distillation device, combining the reaction process with the distillation process, the reaction products can be directly preliminarily separated. The cyclopentadiene generated after partial cracking of dicyclopentadiene in the reaction kettle reacts with a large amount of norbornene around to form tetracyclododecene. At the same time, the remaining C9 fraction and norbornene in the reaction are also partially separated through the rectification column, saving equipment costs, reducing energy consumption, and improving the rectification effect.

[0020] (3) The light components and heavy components of the C9 fraction are separated by two-stage rectification to facilitate subsequent applications in different directions, and the remaining norbornene in the reaction is also recovered. In addition, two-stage rectification is used in the light component rectification, which can make the purity of the norbornene returned to the reaction system in the system higher.

[0021] (4) The intermediate products formed can also be used as fuel.

[0022] In summary, the present invention provides a method for preparing tetracyclododecene from C9 fraction and norbornene in a reactive distillation device, which reduces the equipment and raw material costs and expands the downstream applications of C9 fraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow diagram for synthesizing tetracyclododecene of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The exemplary embodiments of the present invention are described in detail below. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be achieved and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The principles and features of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0025] The flowcharts of the examples and comparative examples are shown inFigure 1 The content of each component in the material is determined by gas chromatography.

[0026] The method for preparing cyclododecene by reactive distillation used in the examples comprises the following steps:

[0027] S1: The C9 fraction and norbornene are mixed in a mixer, and then the mixed material is heated and reacted in the reaction kettle of the reactive distillation device. The dicyclopentadiene in the C9 fraction is cracked into cyclopentadiene at high temperature and reacts with a large amount of norbornene around to form cyclododecene.

[0028] S2: The reacted material is directly rectified in the reactive distillation device. The unreacted C9 fraction and norbornene are obtained at the top of the rectifying column section, and the crude cyclododecene product is obtained in the reaction kettle section of the rectifying column.

[0029] S3: The overhead product of the rectifying column section in the reactive distillation device is subjected to two-stage rectification to remove the light components and heavy components, and then norbornene is obtained and sent back to the mixer.

[0030] S4: The crude cyclododecene product in the reaction kettle section of the rectifying column in the reactive distillation device is separated from the high-boiling components in the third rectifying column to obtain a high-purity cyclododecene product.

[0031] The differences between the examples lie in the values of the experimental parameters.

[0032] Example 1

[0033] The content of dicyclopentadiene in the C9 component of the raw material is 32.61%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 20:1. The set reaction pressure is 0.2 MPa, the reaction temperature is 180 °C, the reaction residence time is 30 min, and the overhead temperature of the rectifying column part in the reactive distillation device is 145 °C. In the rectification section, the overhead temperature of the first rectifying column is 70 °C, and the bottom temperature is 85 °C; the overhead temperature of the second rectifying column is 98 °C, and the bottom temperature is 130 °C; the set pressure at the top of the third rectifying column is 0.5 kPa, the set temperature is 95 °C, the set pressure at the bottom is 10 kPa, and the set temperature is 160 °C.

[0034] Example 2

[0035] The content of dicyclopentadiene in the C9 components of the raw material is 32.61%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 10:1. The set reaction pressure is 0.2 MPa, the reaction temperature is 180 °C, the reaction residence time is 30 min, and the top temperature of the distillation column part in the reactive distillation device is 150 °C. In the distillation section, the top temperature of the first distillation column is 65 °C, and the bottom temperature is 80 °C; the top temperature of the second distillation column is 95 °C, and the bottom temperature is 135 °C; the set pressure at the top of the third distillation column is 0.2 kPa, the set temperature is 135 °C, the set pressure at the bottom is 1 kPa, and the set temperature is 160 °C.

[0036] Example 3

[0037] The content of dicyclopentadiene in the C9 components of the raw material is 33.45%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 25:1. The set reaction pressure is 0.2 MPa, the reaction temperature is 250 °C, the reaction residence time is 10 min, and the top temperature of the distillation column part in the reactive distillation device is 120 °C. In the distillation section, the top temperature of the first distillation column is 75 °C, and the bottom temperature is 95 °C; the top temperature of the second distillation column is 110 °C, and the bottom temperature is 120 °C; the set pressure at the top of the third distillation column is 0.6 kPa, the set temperature is 65 °C, the set pressure at the bottom is 15 kPa, and the set temperature is 90 °C.

[0038] Example 4

[0039] The content of dicyclopentadiene in the C9 components of the raw material is 30.77%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 20:1. The set reaction pressure is 0.1 MPa, the reaction temperature is 150 °C, the reaction residence time is 30 min, and the top temperature of the distillation column part in the reactive distillation device is 130 °C. In the distillation section, the top temperature of the first distillation column is 70 °C, and the bottom temperature is 90 °C; the top temperature of the second distillation column is 100 °C, and the bottom temperature is 135 °C; the set pressure at the top of the third distillation column is 0.4 kPa, the set temperature is 95 °C, the set pressure at the bottom is 8 kPa, and the set temperature is 155 °C.

[0040] Example 5

[0041] The content of dicyclopentadiene in the C9 components of the raw material is 32.19%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 20:1. The reaction pressure is set at 0.5 MPa, the reaction temperature is 180 °C, the reaction residence time is 120 min, and the top temperature of the distillation column part in the reactive distillation unit is 145 °C. In the distillation section, the top temperature of the first distillation column is 70 °C, and the bottom temperature is 85 °C; the top temperature of the second distillation column is 105 °C, and the bottom temperature is 130 °C; the set pressure at the top of the third distillation column is 0.3 kPa, the set temperature is 95 °C, the set pressure at the bottom is 5 kPa, and the set temperature is 160 °C.

[0042] Comparative Example 1

[0043] The content of dicyclopentadiene in the C9 components of the raw material is 35.06%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 2:1. The reaction pressure is set at 0.2 MPa, the reaction temperature is 180 °C, the reaction residence time is 30 min, and the top temperature of the distillation column part in the reactive distillation unit is 145 °C. In the distillation section, the top temperature of the first distillation column is 70 °C, and the bottom temperature is 85 °C; the top temperature of the second distillation column is 98 °C, and the bottom temperature is 130 °C; the set pressure at the top of the third distillation column is 0.5 kPa, the set temperature is 95 °C, the set pressure at the bottom is 10 kPa, and the set temperature is 160 °C.

[0044] Comparative Example 2

[0045] The content of dicyclopentadiene in the C9 components of the raw material is 35.06%, and the content of norbornene is 99%. The molar ratio of norbornene to dicyclopentadiene in the mixer is 20:1. The reaction pressure is set at 0.2 MPa, the reaction temperature is 180 °C, the reaction residence time is 300 min, and the top temperature of the distillation column part in the reactive distillation unit is 125 °C. In the distillation section, the top temperature of the first distillation column is 70 °C, and the bottom temperature is 85 °C; the top temperature of the second distillation column is 98 °C, and the bottom temperature is 1240 °C; the set pressure at the top of the third distillation column is 0.4 kPa, the set temperature is 95 °C, the set pressure at the bottom is 10 kPa, and the set temperature is 160 °C.

[0046] The process conditions of the reactors in all the above examples and comparative examples are listed in Table 1, and the corresponding conversion rate of dicyclopentadiene, purity and yield of tetracyclododecene are listed in Table 2.

[0047] Table 1 Reactor Process Conditions

[0048]

[0049] Table 2 Product Performance

[0050] Conversion rate of dicyclopentadiene / % Purity of tetracyclododecane tetraene / % Yield of tetracyclododecene / % Example 1 96 99 88 Example 2 94 99 81 Example 3 96 99 83 Example 4 96 99 86 Example 5 98 99 82 Comparative Example 1 61 94 34 Comparative Example 2 99 99 76

[0051] As can be seen from Table 1 and Table 2, the molar ratio of norbornene to dicyclopentadiene in the raw materials and the reaction time have a great influence on the reaction results. If the molar ratio is too low or the reaction time is too long, the yield of cyclododecatetraene will decrease or even the purity will not meet the standard.

[0052] By using the method of the present invention, the obtained cyclododecatetraene all has a high purity (≥99%). That is, when using the C9 fraction as the source of dicyclopentadiene and using a reactive distillation device to carry out the cyclododecatetraene synthesis reaction and the separation process of the C9 fraction simultaneously, a high-purity cyclododecatetraene product can be obtained. Compared with the prior art, the greatest advantage of the present invention is to reduce the raw material cost. The prior art usually uses high-purity dicyclopentadiene as the raw material, while the present invention uses the C9 fraction as the raw material, and the cost of the C9 fraction is much lower than that of high-purity dicyclopentadiene, and a high product purity is also obtained. At the same time, the present invention also expands the downstream application of the C9 fraction, having obvious technical advantages.

[0053] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for preparing cyclododecene by reactive distillation, characterized in that, It includes the following steps: S1: Mix the C9 fraction and norbornene in a mixer, and then heat and react the mixed material in the reaction kettle of the reactive distillation device. Dicyclopentadiene in the C9 fraction cracks into cyclopentadiene at high temperature and reacts with a large amount of norbornene around it to generate tetracyclododecene; S2: Directly distill the material after the reaction in the reactive distillation device. The unreacted C9 fraction and norbornene are obtained at the top of the distillation column section, and the crude product of tetracyclododecene is obtained in the reaction kettle section of the distillation column; S3: Remove the light components and heavy components from the top product of the distillation column section in the reactive distillation device through two-stage distillation to obtain norbornene and send it back to the mixer; S4: Separate the high-boiling components from the crude product of tetracyclododecene in the reaction kettle section of the distillation column in the reactive distillation device to obtain a high-purity tetracyclododecene product.

2. The method for preparing cyclododecene by reactive distillation according to claim 1, wherein: In step S1, the mass content of the norbornene is ≥99%.

3. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S1, the mass content of dicyclopentadiene in the C9 raw material is ≥30%.

4. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S1, the rotation speed of the mixer is 500 - 2200 r / min, and the stirring time is 10 - 90 min.

5. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S1, the molar ratio of the norbornene added in the mixer to the dicyclopentadiene in the C9 raw material is (10 - 25):

1.

6. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S1, the reaction temperature of the heating reaction is 150°C - 250°C, the reaction time is 10 min - 120 min, and the pressure in the reaction kettle is 0.1 - 0.5 MPa.

7. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S1, the material obtained by the reaction is directly distilled in the reactive distillation device.

8. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S2, the distillation is atmospheric distillation, and the temperature is 120°C - 150°C.

9. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S2, the unreacted C9 fraction and norbornene obtained at the top of the reactive distillation device are sent to the first distillation column, and the material in the reaction kettle of the reactive distillation device is sent to the third distillation column.

10. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S3, the first distillation column is atmospheric distillation, the top temperature is 65°C - 75°C, and the bottom temperature is 80°C - 95°C; the light components with lower boiling points in the C9 fraction are separated at the top of the first distillation column, and the bottom material is sent to the second distillation column.

11. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S3, the second distillation column is atmospheric distillation, the top temperature is 95°C - 110°C, and the bottom temperature is 120°C - 135°C; the remaining norbornene obtained at the top of the second distillation column is returned to the mixer, and the heavy components with higher boiling points in the C9 fraction are separated at the bottom.

12. A method for preparing cyclododecene by reactive distillation according to claim 1, characterized in that: In step S4, the third distillation column is vacuum distillation, the top pressure is set to 0.2 - 0.6 kPa, the top temperature is set to 65 - 135°C, the bottom pressure is set to 1 - 15 kPa, and the bottom temperature is set to 90 - 160°C; a high-purity tetracyclododecene product is obtained at the top, and high-boiling by-products are separated at the bottom.

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