Device and method for preparing cyclopentadiene and 2-methylstyrene

Abstract

The invention belongs to the technical field of ethylene, and relates to a device and a method for preparing cyclopentadiene and 2-methylstyrene. The device comprises a reactive distillation tower, a light component removal tower, a heavy component removal tower, an extractive distillation tower and a solvent recovery tower, wherein the tower top of the reactive distillation tower is connected with the light component removal tower, and the tower bottom of the reactive distillation tower is connected with the heavy component removal tower; the tower top of the heavy component removal tower is connected with the extractive distillation tower; the tower bottom of the extractive distillation tower is connected with the solvent recovery tower; and the tower bottom of the solvent recovery tower is connected with the extractive distillation tower. According to the device and the method disclosed by the invention, the utilization rate of C9 resources can be increased, 2-methylstyrene with relatively high content is also separated and utilized while cyclopentadiene is separated, and the purity and the yield of the prepared cyclopentadiene and 2-methylstyrene are relatively high.

Description

Technical Field

[0001] The present invention belongs to the technical field of ethylene, and specifically, relates to a device for preparing cyclopentadiene and 2-methylstyrene, and a method for preparing cyclopentadiene and 2-methylstyrene. Background Art

[0002] Cyclopentadiene (CPD) is a raw material for producing important organic chemical products such as norbornene, unsaturated polyester, ethylene-propylene rubber, glutaraldehyde, ferrocene, etc., and can also be used in the synthesis of pesticides, spices, and pharmaceutical intermediates. 2-Methylstyrene is an aromatic hydrocarbon derivative and an important intermediate for pharmaceutical R & D and synthesis, and is expensive.

[0003] After the light fractions below C8 are separated from the cracking raw materials obtained by cracking petroleum to produce ethylene, a considerable amount of C9 fraction is obtained. The composition of this fraction is complex and contains dicyclopentadiene, methylcyclopentadiene dimer, trimethylbenzene, 2-methylstyrene, indene, naphthalene compounds, etc. Most of these substances have high utilization value, such as cyclopentadiene, 2-methylstyrene, etc. With the continuous development of the million-ton large ethylene technology in China, the output of cracking C9 fraction is increasing continuously. Cyclopentadiene and 2-methylstyrene account for more than 30% of the raw materials. However, at present, most of the C9 fraction is used as fuel and a small amount is used as solvent oil, and the added value and economic benefits of the products are relatively low. With the development of high-end chemicals such as biomedicine in China, the demand for important intermediates is increasing. Therefore, separating high-purity cyclopentadiene and 2-methylstyrene from the C9 fraction can improve the economic value of C9 resources and promote the development of high-end chemicals in China.

[0004] In the existing technology, cyclopentadiene can be separated from the C9 fraction, but 2-methylstyrene cannot be separated from the C9 and is mainly synthesized by reaction, which is expensive.

[0005] The process method proposed by Xie Meini et al. uses the cracking C9 fraction. After removing cyclopentadiene from the cracking C9 fraction, the remaining fraction is used for resin production, but there are still a large number of styrene active substances in the remaining components that are not fully utilized. CN 115124403 A introduces a method for single-column rectification separation of cracking C9 in a petroleum resin system, obtaining a mixture of dicyclopentadiene, indene, styrene, etc., but the separation of single active components is not achieved.

[0006] In summary, in the existing cracking C9 utilization processes, the separation of high-purity cyclopentadiene and 2-methylstyrene cannot be satisfied simultaneously. Summary of the Invention

[0007] The object of the present invention is to overcome the defect that the existing preparation methods cannot simultaneously meet the separation of high-purity cyclopentadiene and 2-methylstyrene, and to provide an apparatus and a method for preparing cyclopentadiene and 2-methylstyrene.

[0008] The first aspect of the present invention provides an apparatus for preparing cyclopentadiene and 2-methylstyrene, including a reactive distillation column, a light component removal column, a heavy component removal column, an extractive distillation column and a solvent recovery column; wherein,

[0009] The top of the reactive distillation column is connected to the light component removal column, and the bottom is connected to the heavy component removal column;

[0010] The top of the heavy component removal column is connected to the extractive distillation column;

[0011] The bottom of the extractive distillation column is connected to the solvent recovery column;

[0012] The bottom of the solvent recovery column is connected to the extractive distillation column.

[0013] The second aspect of the present invention provides a method for preparing cyclopentadiene and 2-methylstyrene, including the following steps:

[0014] (1) Depolymerize and rectify the C9 raw material in the reactive distillation column, cool the top of the column to obtain a cyclopentadiene fraction, and obtain a reactive distillation column heavy component at the bottom;

[0015] (2) Feed the cyclopentadiene fraction obtained at the top in step (1) into the light component removal column for purification, obtain a light component at the top of the column, and obtain high-purity cyclopentadiene at the bottom;

[0016] (3) Feed the reactive distillation column heavy component obtained at the bottom in step (1) into the heavy component removal column for purification, obtain a fraction containing 2-methylstyrene at the top of the column, and obtain a heavy component removal column heavy component at the bottom;

[0017] (4) Feed the fraction containing 2-methylstyrene obtained at the top in step (3) into the extractive distillation column for extractive distillation, obtain an extractive distillation column light component at the top of the column, and obtain a fraction rich in 2-methylstyrene at the bottom;

[0018] (5) Feed the fraction rich in 2-methylstyrene obtained at the bottom in step (4) into the solvent recovery column for purification, obtain high-purity 2-methylstyrene at the top of the column, and obtain an extractant at the bottom to be returned to the extractive distillation column for recycling.

[0019] The present invention continuously separates cracked C9 to prepare cyclopentadiene and 2-methylstyrene by combining a reactive distillation column and an extractive distillation column. The raw material used is C9 fraction: First, the C9 fraction enters the reactive distillation column. By controlling the conditions of the reactive distillation column, dicyclopentadiene (DCPD) is continuously depolymerized in the reactive distillation column to generate CPD, which is withdrawn from the top of the column. After removing the light components in the light component removal column, a high-purity CPD product is obtained at the bottom of the column. At the same time, the heavy components at the bottom of the reactive distillation column enter the heavy component removal column. After removing the heavy components, the fraction containing 2-methylstyrene is obtained at the top of the column and enters the extractive distillation column. By controlling the conditions, the separation of 2-methylstyrene is achieved. The yields and purities of the obtained cyclopentadiene and 2-methylstyrene are both relatively high, with the purity reaching over 90% and the yield being as high as over 85%.

[0020] The device and method of the present invention can improve the utilization rate of C9 resources. While separating cyclopentadiene, the relatively high-content 2-methylstyrene is also separated and utilized. The purities and yields of the prepared cyclopentadiene and 2-methylstyrene are both relatively high.

[0021] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0022] Figure 1 is a process flow diagram for preparing cyclopentadiene and 2-methylstyrene in a specific implementation manner of the present invention.

[0023] Description of the Reference Numerals in the Drawings

[0024] 1 Reactive distillation column; 2 Light component removal column; 3 Heavy component removal column; 4 Extractive distillation column; 5 Solvent recovery column;

[0025] a C9 raw material; b Light components; c Cyclopentadiene; d Extractant; e 2-Methylstyrene. Specific Implementation Manner

[0026] The following provides a detailed description of the specific implementation manner of the present invention. It should be understood that the specific implementation manner described herein is only used to illustrate and explain the present invention and is not used to limit the present invention.

[0027] The present invention provides a device for preparing cyclopentadiene and 2-methylstyrene, as Figure 1 shown, including a reactive distillation column, a light component removal column, a heavy component removal column, an extractive distillation column, and a solvent recovery column; wherein,

[0028] The top of the reactive distillation column is connected to the light component removal column, and the bottom is connected to the heavy component removal column;

[0029] The top of the heavy component removal column is connected to the extractive distillation column;

[0030] The bottom of the extractive distillation column is connected to the solvent recovery column;

[0031] The bottom of the solvent recovery column is connected to the extractive distillation column.

[0032] According to a specific embodiment of the present invention, the reactive distillation column is provided with a C9 raw material feed pipeline, a light component discharge pipeline at the top of the reactive distillation column, and a heavy component discharge pipeline at the bottom of the reactive distillation column; the reactive distillation column is connected to the light component removal column through the light component discharge pipeline at the top of the reactive distillation column and is connected to the heavy component removal column through the heavy component discharge pipeline at the bottom of the reactive distillation column.

[0033] According to a specific embodiment of the present invention, the light component removal column is provided with a light component discharge pipeline at the top of the light component removal column and a cyclopentadiene discharge pipeline at the bottom.

[0034] According to a specific embodiment of the present invention, the heavy component removal column is provided with a light component discharge pipeline at the top of the heavy component removal column and a heavy component discharge pipeline at the bottom of the heavy component removal column; the heavy component removal column is connected to the extractive distillation column through the light component discharge pipeline at the top of the heavy component removal column.

[0035] According to a specific embodiment of the present invention, the extractive distillation column is provided with an extractant feed pipeline, a light component discharge pipeline at the top of the extractive distillation column, and a heavy component discharge pipeline at the bottom of the extractive distillation column; the extractive distillation column is connected to the solvent recovery column through the heavy component discharge pipeline at the bottom of the extractive distillation column.

[0036] According to a specific embodiment of the present invention, the solvent recovery column is provided with a 2-methylstyrene discharge pipeline at the top and a heavy component discharge pipeline at the bottom of the solvent recovery column; the heavy component discharge pipeline at the bottom of the solvent recovery column converges with the extractant feed pipeline.

[0037] The present invention also provides a method for preparing cyclopentadiene and 2-methylstyrene, comprising the following steps:

[0038] (1) Depolymerizing and rectifying the C9 raw material in the reactive distillation column, cooling the top of the column to obtain a cyclopentadiene fraction, and obtaining the reactive distillation column heavy components at the bottom;

[0039] (2) Feeding the cyclopentadiene fraction obtained at the top in step (1) into the light component removal column for purification, obtaining light components at the top of the column, and obtaining high-purity cyclopentadiene at the bottom;

[0040] (3) Feeding the reactive distillation column heavy components obtained at the bottom in step (1) into the heavy component removal column for purification, obtaining a fraction containing 2-methylstyrene at the top of the column, and obtaining the heavy component removal column heavy components at the bottom;

[0041] (4) Feed the fraction containing 2-methylstyrene obtained at the top of the column in step (3) into an extractive distillation column for extractive distillation. The light components of the extractive distillation column are obtained at the top of the column, and the fraction rich in 2-methylstyrene is obtained at the bottom of the column.

[0042] (5) Feed the fraction rich in 2-methylstyrene obtained at the bottom of the column in step (4) into a solvent recovery column for purification. High-purity 2-methylstyrene is obtained at the top of the column, and the extractant is obtained at the bottom of the column and returned to the extractive distillation column for recycling.

[0043] According to the present invention, preferably, the operating conditions of the reactive distillation column include: the number of theoretical plates is 20 - 50, the top temperature of the column is 30 - 50 °C, the top pressure of the column is atmospheric pressure, the bottom temperature of the column is 180 - 230 °C, and the reflux ratio is 5 - 20.

[0044] According to the present invention, preferably, the operating conditions of the light component removal column include: the number of theoretical plates is 50 - 80, the bottom temperature of the column is 40 - 80 °C, and the reflux ratio is 10 - 30.

[0045] According to the present invention, preferably, the operating conditions of the heavy component removal column include: the number of theoretical plates is 50 - 80, the bottom temperature of the column is 190 - 220 °C, and the reflux ratio is 5 - 15.

[0046] According to the present invention, preferably, the operating conditions of the extractive distillation column include: the number of theoretical plates is 50 - 90, the operating pressure is 5 - 20 kPa, the bottom temperature of the column is 250 - 330 °C, the reflux ratio is 15 - 25, and the mass ratio of the extractant to the feed is 0.1 - 2, preferably 0.3 - 1.5.

[0047] According to the present invention, preferably, the operating conditions of the solvent recovery column include: the number of theoretical plates is 50 - 80, the bottom temperature of the column is 290 - 410 °C, and the reflux ratio is 5 - 20.

[0048] The extractant used in the present invention can be at least one of glycerol (GLY), N,N-dimethylformamide (DMF), sulfolane, and dimethyl sulfoxide (DMSO). Preferably, it is at least two of glycerol, N,N-dimethylformamide, sulfolane, and dimethyl sulfoxide. For example, a compound solvent of N,N-dimethylformamide and other extractants, and the mass ratio of the two is 5 - 15:1, preferably 8 - 10:1.

[0049] In the present invention, the C9 raw material refers to the ethylene cracking C9 fraction, which usually contains but is not limited to dicyclopentadiene, 2-methylstyrene and its homologues, indene and its homologues.

[0050] The present invention will be further described below in conjunction with examples, but the scope of the present invention is not limited to these examples.

[0051] The component contents of the ethylene pyrolysis C9 raw material used in the following examples are as follows: dicyclopentadiene 17.69%, 2-methylstyrene and homologues 21.37%, indene and homologues 12.28%.

[0052] The following examples all adopt the process flow as Figure 1 shown, and the devices used include: reactive distillation column 1, light component removal column 2, heavy component removal column 3, extractive distillation column 4 and solvent recovery column 5; among them,

[0053] The reactive distillation column 1 is provided with a C9 raw material feed pipeline, a light component discharge pipeline at the top of the reactive distillation column, and a heavy component discharge pipeline at the bottom of the reactive distillation column; the reactive distillation column 1 is connected to the light component removal column 2 through the light component discharge pipeline at the top of the reactive distillation column and is connected to the heavy component removal column 3 through the heavy component discharge pipeline at the bottom of the reactive distillation column.

[0054] The light component removal column 2 is provided with a light component discharge pipeline at the top of the light component removal column and a cyclopentadiene discharge pipeline at the bottom.

[0055] The heavy component removal column 3 is provided with a light component discharge pipeline at the top of the heavy component removal column and a heavy component discharge pipeline at the bottom of the heavy component removal column; the heavy component removal column 3 is connected to the extractive distillation column 4 through the light component discharge pipeline at the top of the heavy component removal column.

[0056] The extractive distillation column 4 is provided with an extractant feed pipeline at the upper part, a light component discharge pipeline at the top of the extractive distillation column, and a heavy component discharge pipeline at the bottom of the extractive distillation column; the extractive distillation column 4 is connected to the solvent recovery column 5 through the heavy component discharge pipeline at the bottom of the extractive distillation column.

[0057] The solvent recovery column 5 is provided with a 2-methylstyrene discharge pipeline at the top and a heavy component discharge pipeline at the bottom of the solvent recovery column; the heavy component discharge pipeline at the bottom of the solvent recovery column converges with the extractant feed pipeline.

[0058] Example 1

[0059] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, and is carried out in the above device by adopting the Figure 1 process flow shown, including the following steps:

[0060] (1) Carry out depolymerization rectification of the C9 raw material a in the reactive distillation column 1. The theoretical number of plates of the reactive distillation column 1 is 30, the reflux ratio is set to 10, the bottom temperature of the column is 215 °C, the top pressure of the column is normal pressure, and the top is cooled at 38 °C to obtain a cyclopentadiene fraction, and the bottom of the column obtains the heavy components of the reactive distillation column.

[0061] (2) Feed the cyclopentadiene fraction obtained from the top of the column in step (1) into the light component removal column 2 for purification. The light component removal column 2 has 60 theoretical plates, a reflux ratio of 13, and a bottom temperature of 53 °C. The light component b is obtained from the top of the column, and high-purity cyclopentadiene c is obtained from the bottom of the column.

[0062] (3) Feed the heavy components of the reactive distillation column obtained from the bottom of the column in step (1) into the heavy component removal column 3 for purification. The heavy component removal column 3 has 60 theoretical plates, a reflux ratio of 5, and a bottom temperature of 203 °C. A fraction containing 2-methylstyrene is obtained from the top of the column, and the heavy component removal column heavy components are obtained from the bottom of the column.

[0063] (4) Feed the fraction containing 2-methylstyrene obtained from the top of the column in step (3) into the extractive distillation column 4 for extractive distillation. The extractant d (glycerol + N,N-dimethylformamide, with a mass ratio of 9:1) is fed into the upper part of the extractive distillation column 4 at room temperature. The extractive distillation column 4 has 70 theoretical plates, a reflux ratio of 18, a bottom temperature of 319 °C, and is operated at 10 kPa. The mass flow ratio of the extractant d to the raw material is 0.65. The light components of the extractive distillation column are obtained from the top of the column, and a fraction rich in 2-methylstyrene is obtained from the bottom of the column.

[0064] (5) Feed the fraction rich in 2-methylstyrene obtained from the bottom of the column in step (4) into the solvent recovery column 5 for purification. The solvent recovery column 5 has 60 theoretical plates, is operated at atmospheric pressure, has a reflux ratio of 8, and a bottom temperature of 373 °C. High-purity 2-methylstyrene e is obtained by cooling the top of the column at 167 °C, and the extractant is obtained from the bottom of the column and returned to the extractive distillation column 4 for recycling.

[0065] Example 2

[0066] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, and is carried out in the above device using the Figure 1 process flow shown, including the following steps:

[0067] (1) Carry out depolymerization distillation of the C9 raw material a in the reactive distillation column 1. The reactive distillation column 1 has 30 theoretical plates, a reflux ratio of 15, a bottom temperature of 215 °C, and a top pressure of atmospheric pressure. The cyclopentadiene fraction is obtained by cooling the top of the column at 38 °C, and the reactive distillation column heavy components are obtained from the bottom of the column.

[0068] (2) Feed the cyclopentadiene fraction obtained from the top of the column in step (1) into the light component removal column 2 for purification. The light component removal column 2 has 60 theoretical plates, a reflux ratio of 12, and a bottom temperature of 53 °C. The light component b is obtained from the top of the column, and high-purity cyclopentadiene c is obtained from the bottom of the column.

[0069] (3) The heavy components obtained at the bottom of the reaction distillation column in step (1) are fed into the heavy component removal column 3 for purification. The number of theoretical plates of the heavy component removal column 3 is 60, the reflux ratio is set to 7, the column bottom temperature is 202 °C, a fraction containing 2-methylstyrene is obtained at the top of the column, and the heavy components of the heavy component removal column are obtained at the bottom of the column.

[0070] (4) The fraction containing 2-methylstyrene obtained at the top of the column in step (3) is fed into the extractive distillation column 4 for extractive distillation. The extractant d (glycerol + N,N-dimethylformamide, with a mass ratio of 9:1) is fed into the upper part of the extractive distillation column 4 at room temperature. The number of theoretical plates of the extractive distillation column 4 is 70, the reflux ratio is set to 15, the column bottom temperature is 319 °C, and it operates at 10 kPa. The mass flow ratio of the extractant d to the raw material is 0.65. The light components of the extractive distillation column are obtained at the top of the column, and a fraction rich in 2-methylstyrene is obtained at the bottom of the column.

[0071] (5) The fraction rich in 2-methylstyrene obtained at the bottom of the column in step (4) is fed into the solvent recovery column 5 for purification. The number of theoretical plates of the solvent recovery column 5 is 60, it operates at atmospheric pressure, the reflux ratio is set to 8, the column bottom temperature is 373 °C, and high-purity 2-methylstyrene e is obtained by cooling at 167 °C at the top of the column, and the extractant is obtained at the bottom of the column and returned to the extractive distillation column 4 for recycling.

[0072] Example 3

[0073] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, which is carried out in the above device using the Figure 1 process flow shown, and includes the following steps:

[0074] (1) The C9 raw material a is subjected to depolymerization distillation in the reaction distillation column 1. The number of theoretical plates of the reaction distillation column 1 is 40, the reflux ratio is set to 8, the column bottom temperature is 215 °C, the top pressure of the column is atmospheric pressure, and the cyclopentadiene fraction is obtained by cooling at 38 °C at the top of the column, and the heavy components of the reaction distillation column are obtained at the bottom of the column.

[0075] (2) The cyclopentadiene fraction obtained at the top of the column in step (1) is fed into the light component removal column 2 for purification. The number of theoretical plates of the light component removal column 2 is 50, the reflux ratio is set to 20, the column bottom temperature is 53 °C, the light component b is obtained at the top of the column, and high-purity cyclopentadiene c is obtained at the bottom of the column.

[0076] (3) The heavy components obtained at the bottom of the reaction distillation column in step (1) are fed into the heavy component removal column 3 for purification. The number of theoretical plates of the heavy component removal column 3 is 70, the reflux ratio is set to 10, the column bottom temperature is 202 °C, a fraction containing 2-methylstyrene is obtained at the top of the column, and the heavy components of the heavy component removal column are obtained at the bottom of the column.

[0077] (4) The fraction containing 2-methylstyrene obtained from the top of the tower in step (3) is introduced into the extractive distillation column 4 for extractive distillation. The extractant d (glycerol + N,N-dimethylformamide, with a mass ratio of 9:1) is fed from the upper part of the extractive distillation column 4 at room temperature. The number of theoretical plates of the extractive distillation column 4 is 80, the reflux ratio is set to 20, the bottom temperature of the column is 319 °C, and it operates at 10 kPa. The mass flow ratio of the extractant d to the raw material is 0.65. The light components of the extractive distillation column are obtained at the top of the column, and the fraction rich in 2-methylstyrene is obtained at the bottom of the column.

[0078] (5) The fraction rich in 2-methylstyrene obtained from the bottom of the column in step (4) is introduced into the solvent recovery column 5 for purification. The number of theoretical plates of the solvent recovery column 5 is 60, it operates at atmospheric pressure, the reflux ratio is set to 10, and the bottom temperature of the column is 373 °C. High-purity 2-methylstyrene e is obtained by cooling at 167 °C at the top of the column, and the extractant is obtained at the bottom of the column and returned to the extractive distillation column 4 for recycling.

[0079] Example 4

[0080] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, which is carried out in the above device using the Figure 1 shown process flow, including the following steps:

[0081] (1) The C9 raw material a is subjected to depolymerization distillation in the reactive distillation column 1. The number of theoretical plates of the reactive distillation column 1 is 40, the reflux ratio is set to 15, the bottom temperature of the column is 215 °C, and the top pressure of the column is atmospheric pressure. The cyclopentadiene fraction is obtained by cooling at 38 °C at the top of the column, and the heavy components of the reactive distillation column are obtained at the bottom of the column.

[0082] (2) The cyclopentadiene fraction obtained from the top of the column in step (1) is introduced into the light component removal column 2 for purification. The number of theoretical plates of the light component removal column 2 is 50, the reflux ratio is set to 20, and the bottom temperature of the column is 53 °C. The light components b are obtained at the top of the column, and high-purity cyclopentadiene c is obtained at the bottom of the column.

[0083] (3) The heavy components of the reactive distillation column obtained from the bottom of the column in step (1) are introduced into the heavy component removal column 3 for purification. The number of theoretical plates of the heavy component removal column 3 is 50, the reflux ratio is set to 5, and the bottom temperature of the column is 202 °C. The fraction containing 2-methylstyrene is obtained at the top of the column, and the heavy components of the heavy component removal column are obtained at the bottom of the column.

[0084] (4) The fraction containing 2-methylstyrene obtained from the top of the tower in step (3) is fed into an extractive distillation column 4 for extractive distillation. The extractant d (dimethyl sulfoxide + N,N-dimethylformamide, with a mass ratio of 9:1) is fed into the upper part of the extractive distillation column 4 at room temperature. The extractive distillation column 4 has 70 theoretical plates, a reflux ratio of 20, a bottom temperature of 280 °C, and operates at 10 kPa. The mass flow ratio of the extractant d to the raw material is 0.65. The light components of the extractive distillation column are obtained at the top of the tower, and the fraction rich in 2-methylstyrene is obtained at the bottom of the tower.

[0085] (5) The fraction rich in 2-methylstyrene obtained from the bottom of the tower in step (4) is fed into a solvent recovery column 5 for purification. The solvent recovery column 5 has 80 theoretical plates, operates at atmospheric pressure, has a reflux ratio of 20, and a bottom temperature of 297 °C. High-purity 2-methylstyrene e is obtained by cooling at 167 °C at the top of the tower, and the extractant is obtained at the bottom of the tower and returned to the extractive distillation column 4 for recycling.

[0086] Example 5

[0087] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, which is carried out in the above device using the Figure 1 shown process flow, including the following steps:

[0088] (1) The C9 raw material a is subjected to depolymerization distillation in a reactive distillation column 1. The reactive distillation column 1 has 40 theoretical plates, a reflux ratio of 15, a bottom temperature of 215 °C, and a top pressure of atmospheric pressure. The cyclopentadiene fraction is obtained by cooling at 38 °C at the top of the tower, and the heavy components of the reactive distillation column are obtained at the bottom of the tower.

[0089] (2) The cyclopentadiene fraction obtained from the top of the tower in step (1) is fed into a light component removal tower 2 for purification. The light component removal tower 2 has 50 theoretical plates, a reflux ratio of 20, and a bottom temperature of 53 °C. Light components b are obtained at the top of the tower, and high-purity cyclopentadiene c is obtained at the bottom of the tower.

[0090] (3) The heavy components of the reactive distillation column obtained from the bottom of the tower in step (1) are fed into a heavy component removal tower 3 for purification. The heavy component removal tower 3 has 60 theoretical plates, a reflux ratio of 5, and a bottom temperature of 202 °C. The fraction containing 2-methylstyrene is obtained at the top of the tower, and the heavy components of the heavy component removal tower are obtained at the bottom of the tower.

[0091] (4) Feed the fraction containing 2-methylstyrene obtained from the top of the tower in step (3) into the extractive distillation column 4 for extractive distillation. The extractant d (sulfolane + DMF, with a mass ratio of 9:1) is fed from the upper part of the extractive distillation column 4 at room temperature. The theoretical number of plates of the extractive distillation column 4 is 80, the reflux ratio is set to 20, the bottom temperature of the column is 293 °C, and it operates at 10 kPa. The mass flow ratio of the extractant d to the raw material is 0.5. The light components of the extractive distillation column are obtained at the top of the column, and the fraction rich in 2-methylstyrene is obtained at the bottom of the column.

[0092] (5) Feed the fraction rich in 2-methylstyrene obtained from the bottom of the column in step (4) into the solvent recovery column 5 for purification. The theoretical number of plates of the solvent recovery column 5 is 80, it operates at atmospheric pressure, the reflux ratio is set to 20, and the bottom temperature of the column is 408 °C. High-purity 2-methylstyrene e is obtained by cooling at 167 °C at the top of the column, and the extractant is obtained at the bottom of the column and returned to the extractive distillation column 4 for recycling.

[0093] Example 6

[0094] This example is used to illustrate a method for preparing cyclopentadiene and 2-methylstyrene according to the present invention, which is carried out in the above-mentioned device using the Figure 1 shown process flow, including the following steps:

[0095] (1) Carry out depolymerization distillation of the C9 raw material a in the reactive distillation column 1. The theoretical number of plates of the reactive distillation column 1 is 50, the reflux ratio is set to 15, the bottom temperature of the column is 215 °C, and the top pressure of the column is atmospheric pressure. The cyclopentadiene fraction is obtained by cooling at 38 °C at the top of the column, and the heavy components of the reactive distillation column are obtained at the bottom of the column.

[0096] (2) Feed the cyclopentadiene fraction obtained from the top of the column in step (1) into the light component removal tower 2 for purification. The theoretical number of plates of the light component removal tower 2 is 50, the reflux ratio is set to 20, and the bottom temperature of the column is 53 °C. Light components b are obtained at the top of the column, and high-purity cyclopentadiene c is obtained at the bottom of the column.

[0097] (3) Feed the heavy components of the reactive distillation column obtained from the bottom of the column in step (1) into the heavy component removal tower 3 for purification. The theoretical number of plates of the heavy component removal tower 3 is 60, the reflux ratio is set to 5, and the bottom temperature of the column is 202 °C. The fraction containing 2-methylstyrene is obtained at the top of the column, and the heavy components of the heavy component removal tower are obtained at the bottom of the column.

[0098] (4) The fraction containing 2-methylstyrene obtained from the top of the tower in step (3) is introduced into an extractive distillation column 4 for extractive distillation. The extractant d (sulfolane + DMF, with a mass ratio of 9:1) is fed from the upper part of the extractive distillation column 4 at room temperature. The theoretical number of trays of the extractive distillation column 4 is 60, the reflux ratio is set to 20, the bottom temperature of the column is 274 °C, and it operates at 10 kPa. The mass flow ratio of the extractant d to the raw material is 1. The light components of the extractive distillation column are obtained at the top of the column, and the fraction rich in 2-methylstyrene is obtained at the bottom of the column.

[0099] (5) The fraction rich in 2-methylstyrene obtained from the bottom of the column in step (4) is introduced into a solvent recovery column 5 for purification. The theoretical number of trays of the solvent recovery column 5 is 80, it operates at atmospheric pressure, the reflux ratio is set to 20, and the bottom temperature of the column is 408 °C. High-purity 2-methylstyrene e is obtained by cooling at 167 °C at the top of the column, and the extractant is obtained at the bottom of the column and returned to the extractive distillation column 4 for recycling.

[0100] Test Example 1

[0101] The yields and purities of cyclopentadiene and 2-methylstyrene obtained in each example were tested, and the results are shown in Table 1 below. The contents of dicyclopentadiene and its monomer and 2-methylstyrene in the C9 fraction were pre-tested to obtain the contents of the corresponding components in this batch of C9 fraction. The yield was calculated using the following formula: Yield of cyclopentadiene = mass of obtained dicyclopentadiene / content of dicyclopentadiene and its monomer in the C9 fraction × 100%, Yield of 2-methylstyrene = mass of obtained 2-methylstyrene / content of 2-methylstyrene in the C9 fraction × 100%.

[0102] Table 1

[0103]

[0104] As can be seen from Table 1, the method for preparing cyclopentadiene and 2-methylstyrene from the C9 fraction of the present invention has a high yield, and the prepared cyclopentadiene and 2-methylstyrene have relatively high purities.

[0105] The embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0106] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. An apparatus for preparing cyclopentadiene and 2-methylstyrene, comprising a reactive distillation column, a light component removal column, a heavy component removal column, an extractive distillation column and a solvent recovery column; wherein, The top of the reactive distillation column is connected to the light component removal column, and the bottom is connected to the heavy component removal column; The top of the heavy component removal column is connected to the extractive distillation column; The bottom of the extractive distillation column is connected to the solvent recovery column; The bottom of the solvent recovery column is connected to the extractive distillation column.

2. The apparatus for preparing cyclopentadiene and 2-methylstyrene according to claim 1, wherein, The reactive distillation column is provided with a C9 raw material feed pipeline, a light component discharge pipeline at the top of the reactive distillation column, and a heavy component discharge pipeline at the bottom of the reactive distillation column; the reactive distillation column is connected to the light component removal column through the light component discharge pipeline at the top of the reactive distillation column, and is connected to the heavy component removal column through the heavy component discharge pipeline at the bottom of the reactive distillation column.

3. The apparatus for preparing cyclopentadiene and 2-methylstyrene according to claim 1, wherein, The top of the light component removal column is provided with a light component discharge pipeline at the top of the light component removal column, and the bottom is provided with a cyclopentadiene discharge pipeline.

4. The apparatus for preparing cyclopentadiene and 2-methylstyrene according to claim 1, wherein, The heavy component removal column is provided with a light component discharge pipeline at the top of the heavy component removal column and a heavy component discharge pipeline at the bottom of the heavy component removal column; the heavy component removal column is connected to the extractive distillation column through the light component discharge pipeline at the top of the heavy component removal column.

5. The apparatus for preparing cyclopentadiene and 2-methylstyrene according to claim 1, wherein, The extractive distillation column is provided with an extractant feed pipeline, a light component discharge pipeline at the top of the extractive distillation column, and a heavy component discharge pipeline at the bottom of the extractive distillation column; the extractive distillation column is connected to the solvent recovery column through the heavy component discharge pipeline at the bottom of the extractive distillation column.

6. The apparatus for preparing cyclopentadiene and 2-methylstyrene according to claim 5, wherein, The top of the solvent recovery column is provided with a 2-methylstyrene discharge pipeline, and the bottom is provided with a heavy component discharge pipeline at the bottom of the solvent recovery column; the heavy component discharge pipeline at the bottom of the solvent recovery column converges with the extractant feed pipeline.

7. A method for preparing cyclopentadiene and 2-methylstyrene, comprising the following steps: (1) Depolymerizing and rectifying the C9 raw material in the reactive distillation column, cooling the top to obtain a cyclopentadiene fraction, and obtaining the heavy components of the reactive distillation column at the bottom; (2) Feeding the cyclopentadiene fraction obtained at the top in step (1) into the light component removal column for refining, obtaining light components at the top, and obtaining high-purity cyclopentadiene at the bottom; (3) Feeding the heavy components of the reactive distillation column obtained at the bottom in step (1) into the heavy component removal column for refining, obtaining a fraction containing 2-methylstyrene at the top, and obtaining the heavy components of the heavy component removal column at the bottom; (4) Feeding the fraction containing 2-methylstyrene obtained at the top in step (3) into the extractive distillation column for extractive distillation, obtaining the light components of the extractive distillation column at the top, and obtaining a fraction rich in 2-methylstyrene at the bottom; (5) Feeding the fraction rich in 2-methylstyrene obtained at the bottom in step (4) into the solvent recovery column for refining, cooling the top to obtain high-purity 2-methylstyrene, and obtaining the extractant at the bottom to be recycled to the extractive distillation column.

8. The method for preparing cyclopentadiene and 2-methylstyrene according to claim 7, wherein, The operating conditions of the reactive distillation column include: the number of theoretical plates is 20 - 50, the top temperature is 30 - 50 °C, the top pressure is atmospheric pressure, the bottom temperature is 180 - 230 °C, and the reflux ratio is 5 - 20; The operating conditions of the light component removal column include: the number of theoretical plates is 50 - 80, the bottom temperature is 40 - 80 °C, and the reflux ratio is 10 - 30; The operating conditions of the heavy component removal column include: the number of theoretical plates is 50 - 80, the bottom temperature is 190 - 220 °C, and the reflux ratio is 5 - 15; The operating conditions of the extractive distillation column include: the number of theoretical plates is 50 - 90, the operating pressure is 5 - 20 kPa, the bottom temperature is 250 - 330 °C, the reflux ratio is 15 - 25, and the mass ratio of the extractant to the feed is 0.1 - 2, preferably 0.3 - 1.5; The operating conditions of the solvent recovery column include: the number of theoretical plates is 50 - 80, the top temperature is 150 - 180 °C, the bottom temperature is 290 - 410 °C, and the reflux ratio is 5 - 20.

9. The method for preparing cyclopentadiene and 2-methylstyrene according to claim 7 or 8, wherein, The extractant is at least one of glycerol, N,N - dimethylformamide, sulfolane, and dimethyl sulfoxide.

10. The method for preparing cyclopentadiene and 2-methylstyrene according to claim 7 or 8, wherein, The C9 raw material is ethylene pyrolysis C9 fraction.

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