A method for producing norbornene

Abstract

The application discloses a production method of norbornene. The method comprises the following steps: reacting ethylene with dicyclopentadiene and / or cyclopentadiene under certain temperature and pressure to obtain a product, which is a gas-liquid mixture containing norbornene, tetracyclododecene, a small amount of polymeric cyclopentadiene, and unreacted cyclopentadiene and / or dicyclopentadiene; performing gradient rectification on the liquid product mixture to obtain norbornene product and by-product tetracyclododecene; and performing rectification and purification on excessive ethylene, unreacted dicyclopentadiene and / or cyclopentadiene and solvent and recycling the rectified and purified ethylene, dicyclopentadiene and / or cyclopentadiene and solvent. In particular, the tetracyclododecene in the by-product is cracked to generate norbornene and cyclopentadiene, so that the norbornene can be produced in a maximum amount. Through the tetracyclododecene cracking process, the yield and selectivity of the norbornene can be remarkably improved, and the economic benefit is relatively high.

Description

Technical Field

[0001] This invention relates to a method for producing norbornene. Background Technology

[0002] Norbornene belongs to the bridged cyclic hydrocarbons. It is a white solid with a pungent, acidic odor. Globally, approximately 95% of norbornene is used as a comonomer in the synthesis of cyclic olefin copolymers / polymers (COC / COP). Cyclic olefin polymers, with their low density, low hygroscopicity, high transparency, high heat resistance, and high refractive index, are widely used in optical and medical materials.

[0003] Norbornene is typically obtained through a Diels-Alder reaction between a dienophile containing unsaturated bonds and a diene containing a conjugated diene structure. Currently, the industrial production processes suitable for norbornene and its derivatives can be divided into two types: liquid-phase reaction processes and gas-phase reaction processes. In liquid-phase reaction processes, cyclopentadiene (CPD) or dicyclopentadiene (DCPD) is in a liquid state during the reaction, and ethylene gas dissolves into the liquid phase for an addition reaction. In gas-phase reaction processes, cyclopentadiene (CPD) or dicyclopentadiene (DCPD) is first heated to vaporize, and then mixed with ethylene gas before entering the reactor to react.

[0004] Chinese patent CN104692993A discloses a method for synthesizing norbornene using a microchannel reactor, employing a microreactor with a feature size of 10-300 micrometers manufactured using precision machining technology. Experiments show that this method has high heat transfer efficiency, rapidly transferring reaction heat into and out of the system, avoiding the generation of reaction hotspots and effectively suppressing side reactions; it also boasts high mass transfer efficiency and is relatively safe, with high raw material conversion rate and norbornene selectivity. However, the microchannel method is difficult to use in industrial-scale mass production of norbornene. Chinese patent CN102249839A discloses a method for synthesizing norbornene using a loop reactor. This method has advantages such as pressure resistance and rapid heat transfer, high safety, and can achieve a high conversion rate of cyclopentadiene. However, experiments show that insufficient backmixing in the loop reactor affects the mass transfer of the system, leading to excessively long residence times and the potential for the formation of more tetracyclic dodecene.

[0005] Chinese patent CN104262074A discloses a method for pyrolyzing dicyclopentadiene to produce cyclopentadiene using hydrogen as a diluent and protective gas, and then synthesizing norbornene with ethylene. It is claimed that using hydrogen can mitigate the carbonization problem that occurs during the pyrolysis of dicyclopentadiene. The amount of hydrogen used should not be too large, because hydrogen is rarely consumed during the reaction, while occupying partial pressure in the system, thereby reducing the partial pressure of ethylene. In experiments, if hydrogen is not removed and the system pressure is maintained at the same level, the amount of polycyclopentadiene produced in the system will increase.

[0006] Japanese Patent JP3991650B2, in the preparation of norbornene using dicyclopentadiene and ethylene, also yielded tetracyclododecene. However, because the method still retained tetracyclododecene, the yield of norbornene was not improved.

[0007] Japanese Patent JP4526142B2, through experimental investigation, discovered that in the preparation of norbornene using dicyclopentadiene and ethylene, the generated norbornene is separated, with a portion recycled and the remainder produced as a product. During this process, the light fractions of norbornene and cyclopentadiene are further distilled to recover cyclopentadiene and some norbornene, significantly improving the conversion rate of dicyclopentadiene. However, a large amount of tetracyclododecene is still produced.

[0008] Chinese patent CN1284052A uses a method of partially monomerizing DCPD to produce a fully controlled mixture between DCPD and ethylene, utilizing endothermic reactions as much as possible to control the total exothermic reaction. Preheating to decompose part of the DCPD allows for good control of the reaction temperature.

[0009] Chinese patent CN115433053A uses a tubular reactor to directly react dicyclopentadiene and ethylene. While this simplifies the production process and significantly reduces equipment investment, energy consumption, and unit consumption, resulting in lower costs, the yield of tetracyclododecene is comparable to that of norbornene. The production ratio of norbornene to tetracyclododecene is lower than expected, and this method cannot produce norbornene alone.

[0010] Chinese patent CN105481625A uses two series-connected batch reactors. The first reactor has a lower temperature and shorter residence time, while the second reactor has a higher temperature and longer residence time. During the reaction, heat balance is achieved through the endothermic depolymerization of dicyclopentadiene and the exothermic reaction of the diene. High ethylene concentration and low cyclopentadiene concentration inhibit the reaction from transitioning to a polymer, while total backmixing addresses mass transfer and heat conversion. However, it does not address how to handle the generated heavy byproducts, resulting in a lower-than-expected norbornene production rate.

[0011] Chinese patent CN103664470A combines the mass transfer advantages of a batch reactor with the process stability and operational safety advantages of a tubular reactor under high-pressure conditions, achieving a norbornene yield of 90-98% in its preparation method. However, the inventors believe that while this method optimizes reaction conditions and reduces byproduct generation, it does not further treat the obtained byproducts, resulting in less effective results than expected. Furthermore, compared to batch reactors, the tubular reactor process for norbornene production results in a greater accumulation of polymers on the reactor walls, thus affecting the economic efficiency and safety of the reactor. Summary of the Invention

[0012] To at least partially address the aforementioned technical problems in the prior art, this invention provides a method for maximizing the production of norbornene. The production method of this invention utilizes a batch reactor, enabling the production equipment to operate stably for extended periods, while significantly improving the conversion rate of dicyclopentadiene and the yield of norbornene.

[0013] As one aspect of the present invention, a method for producing norbornene is provided, the method comprising the following steps:

[0014] S1. An organic solution of mixed ethylene and dicyclopentadiene and / or cyclopentadiene is reacted in a reaction apparatus to obtain a gas-liquid mixture product.

[0015] S2. The gas-liquid mixture obtained in S1 is subjected to flash evaporation separation to recover the gaseous product and obtain the liquid product.

[0016] S3. In the first distillation column, the liquid product obtained in S2 is separated by distillation to obtain distillate product and heavy component by-product.

[0017] S4. In the second distillation column, the fraction from S3 is distilled again and separated to recover cyclopentadiene and obtain norbornene; at the same time, in the third distillation column, the heavy component byproduct is distilled again and separated to obtain organic solvent, cyclopentadiene and heavy component product.

[0018] S5. The heavy component product obtained in S4 is fed into a cracking column for cracking and distillation, and crude norbornene product is obtained from the top outlet of the column.

[0019] S6. The crude norbornene product obtained in S5 is fed to the second distillation column for distillation and purification to recover cyclopentadiene and obtain norbornene.

[0020] In any specific embodiment, in S1, the organic solvent of the organic solution is selected from one or more of cycloalkanes, alkanes, and aromatic organic solvents.

[0021] As a preferred embodiment of the present invention, the organic solvent is selected from one or more of cyclohexane, methylcyclohexane, decane, n-dodecane, and toluene.

[0022] In any specific embodiment, in S1, the molar ratio of ethylene to dicyclopentadiene and / or cyclopentadiene (dicyclopentadiene is converted to cyclopentadiene according to the molar ratio, and is calculated as cyclopentadiene) is (20~40):1, and the mass fraction of dicyclopentadiene and / or cyclopentadiene in the organic solution is 20~60wt%.

[0023] As a preferred condition of the present invention, the molar ratio of ethylene to dicyclopentadiene and / or cyclopentadiene (dicyclopentadiene is converted to cyclopentadiene according to the molar ratio, and is calculated as cyclopentadiene) is (25~35):1, and the mass fraction of dicyclopentadiene and / or cyclopentadiene in the organic solution is 30~50wt%.

[0024] In any specific embodiment, in S1, when both dicyclopentadiene and cyclopentadiene are used as raw materials, the mass fraction of cyclopentadiene is 2~10wt%.

[0025] In any specific embodiment, the reaction apparatus can be adapted to any reaction operating conditions. In S1 of the present invention, the reaction temperature is 100~400℃, the reaction pressure is 1~50MPa, and the reaction residence time is 0.1~10h.

[0026] As a preferred condition of the present invention, in step S1, the reaction temperature is 200~280℃, the reaction pressure is 3~15MPa, and the reaction residence time is 0.3~4h.

[0027] In any specific embodiment, in step S2, the separation temperature is 20~160℃ and the separation pressure is 100~1000kPa.

[0028] As a preferred condition of the present invention, in step S2, the separation temperature is 40~100℃ and the separation pressure is 300~700kPa.

[0029] In any specific embodiment, in S3, the bottom temperature of the first distillation column is 60~130℃, and the distillation pressure is 10~20kPa.

[0030] As a preferred condition of the present invention, in S3, the bottom temperature of the first distillation column is 80~100℃ and the distillation pressure is 13~18kPa.

[0031] In any specific embodiment, in S4, the bottom temperature of the second distillation column is 40~150℃ and the distillation pressure is 1~40kPa; the bottom temperature of the third distillation column is 70~180℃ and the distillation pressure is 30~100kPa.

[0032] As a preferred condition of the present invention, in S4, the bottom temperature of the second distillation column is 80~120℃ and the distillation pressure is 10~16kPa; the bottom temperature of the third distillation column is 110~150℃ and the distillation pressure is 50~80kPa.

[0033] In any specific embodiment, in S5, the temperature of the pyrolysis tower bottom is 120~270℃, and the pressure of the pyrolysis distillation is 1200~1400kPa.

[0034] As a preferred condition of the present invention, in S5, the temperature of the bottom of the cracking tower is 160~240℃, and the pressure of the cracking distillation is 1250~1350kPa.

[0035] In any specific embodiment, in S5, the pyrolysis reaction of the heavy component products is carried out using a solution method.

[0036] In any specific embodiment, the solvent of the solution is a solvent with a boiling point higher than 250°C; the solvent is selected from one or more of benzophenone, diphenyl ether and benzamide.

[0037] In any specific embodiment, the solvent is insulated using an inert solvent storage tank, which is connected to the pyrolysis tower via a temperature tracing pipeline I; the temperature of both the inert solvent storage tank and the temperature tracing pipeline I is set to 150~170℃.

[0038] By adopting the above technical solutions, it is possible to prevent inert solvents or polymer solutions from condensing, depositing, or clogging pipelines.

[0039] In any specific embodiment, in S5, the bottom product of the pyrolysis tower is a batch process. When the viscosity of the bottom solution is greater than 300 cp, product is started and the high-boiling-point solvent is added; when the viscosity of the bottom solution is less than 50 cp, product and the high-boiling-point solvent are stopped.

[0040] In this embodiment of the invention, when the viscosity of the solution in the bottom of the column is greater than 300 cp, the solution in the bottom of the column is started to be drawn out and the high-boiling-point solvent is added at the same time, wherein the amount of solution drawn out from the bottom of the column is equal to the amount of high-boiling-point solvent added.

[0041] By adopting the above technical solution, the viscosity of the solution in the pyrolysis tower bottom can always be kept below 300 cp, thereby preventing the accumulation of polymers in the tower bottom that could clog the pipes, hinder continuous production, or even cause danger.

[0042] In any specific embodiment, in S5, a temperature tracing pipeline II is provided at the outlet of the pyrolysis tower; the temperature of the temperature tracing pipeline II is set to 150~180℃.

[0043] By adopting the above technical solutions, it is possible to prevent inert solvents or polymer solutions from condensing, depositing, or clogging pipelines.

[0044] This invention produces norbornene in the largest quantity by cracking and distilling the heavy component byproducts after primary distillation, especially tetracyclic dodecene. This increases the yield of norbornene, reduces the amount of waste that needs to be treated, saves production costs, and allows for continuous long-term operation, resulting in superior economic benefits.

[0045] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0046] Figure 1 This is a process flow diagram for producing norbornene according to the present invention;

[0047] Figure 2 A process flow diagram for the conventional production of norbornene, omitting the cracking and distillation steps;

[0048] In the diagram: 1. Ethylene tank; 2. DCPD / CPD tank; 3. Reaction apparatus; 4. Flash tank; 5. First distillation column; 6. Second distillation column; 7. Third distillation column; 8. Cracking column; 9. Inert solvent storage tank; 10. Temperature tracing line I; 11. Temperature tracing line II. Detailed Implementation

[0049] The present invention will be further described below with reference to specific embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0050] The inventors discovered in practice that during the production of norbornene, the generated norbornene is prone to further react with cyclopentadiene to form tetracyclododecene (TCD), which leads to a decrease in the yield of norbornene.

[0051] In this embodiment of the invention, when the heavy component byproduct is obtained from the first distillation, it is separately fed to the third distillation column 7 for further distillation to obtain the heavy component product, which is then fed to the cracking column 8. By cracking and distilling the tetracyclic dodecene, the yield of the product norbornene is increased. This not only improves the yield of norbornene but also reduces the amount of waste that needs to be processed, saving production costs and demonstrating superior economic benefits. If all the liquid product were fed into the cracking column 8 without multiple distillations, the cracking column would have to handle large amounts of solvent, norbornene, and cyclopentadiene at the cracking temperature and pressure, resulting in energy waste. Simultaneously, heating the norbornene in the solution would promote the formation of tetracyclic dodecene, polymers, and carbon deposits, the latter two of which cannot be cracked and affect the heating rate, economy, and safety. Furthermore, after completing the second distillation and the cracking and distillation of the heavy component byproduct, this invention recovers and recycles the distilled reactant cyclopentadiene, effectively saving raw material usage and thus reducing overall production costs.

[0052] The materials involved in the following examples are all conventional commercially available products.

[0053] The inventors produced norbornene using the technical solution of this invention, and made the following Examples 1 to 12.

[0054] Example 1

[0055] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 20:1, the mass fraction of dicyclopentadiene in the organic solution is 50%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 2%.

[0056] Norbornene in this embodiment is prepared through the following steps:

[0057] (1) Dicyclopentadiene, organic solvent (cyclohexane:toluene = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 280°C and the pressure was increased to 3MPa. The reaction was held for 4 hours to obtain a gas-liquid mixture.

[0058] (2) Control the separation pressure in flash tank 4 to 300 kPa and the separation temperature to 40°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 13 kPa and the temperature to 80°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 10 kPa and the temperature to 80°C, distill the distillate product twice to obtain norbornene, recover cyclopentadiene and enter it into DCPD / CPD tank 2, and discharge the remaining solvent;

[0059] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 50 kPa and the temperature at 110 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0060] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 150℃, and at the same time control the insulation temperature of the temperature tracing pipeline II 11 to 150℃; control the pressure inside the cracking tower 8 to 1250kPa and the temperature to 160℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: diphenyl ether = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 and are recycled.

[0061] Implementation principle: Refer to the appendix Figure 1 The prepared dicyclopentadiene and organic solvent are pumped into the reaction device 3 from the DCPD / CPD tank 2. The liquid level is monitored in real time by the level gauge. When the liquid level in the reaction device 3 reaches a certain height, the reaction device 3 starts to automatically heat and stir. The ethylene tank 1 is opened and the required ethylene is continuously introduced to raise the temperature and pressure to the required temperature and pressure.

[0062] When the liquid level in reaction device 3 is higher than 70%, the outlet of reaction device 3 is opened under motor adjustment to control the liquid level at 70%. The reaction liquid in reaction device 3 flows continuously out of the outlet into flash tank 4. In flash tank 4, the reaction mixture fed through the inlet undergoes gas-liquid separation. The separated unreacted ethylene comes into contact with the reaction solvent sprayed in the scrubbing device at the top of the tower. The solvent absorbs the unreacted cyclopentadiene and norbornene in the gas and mixes with the reaction liquid, completing the gas-liquid separation.

[0063] After gas-liquid separation, the product continuously enters the first distillation column 5, where it is distilled to separate fractions containing norbornene, solvent, and cyclopentadiene, as well as heavy component byproducts. The resulting liquid-distillate mixture containing norbornene, cyclopentadiene, and solvent is continuously fed into the second distillation column 6, where it is stirred and heated. Norbornene is then separated by distillation, and the recovered cyclopentadiene is sent to the DCPD / CPD tank 2, while the remaining solvent is discharged.

[0064] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7 to separate the solvent and the heavy component product. The heavy component product then enters the cracking column 8. High-boiling-point solvent is pumped into the cracking column 8 from the inert solvent storage tank 9 to ensure that the viscosity of the solution in the bottom of the cracking column 8 is below 300 cp, preventing the accumulation of polymers in the bottom of the column that could clog the pipeline, hinder continuous production, or even cause danger.

[0065] Simultaneously, the insulation temperatures of the inert solvent storage tank 9, the temperature tracing pipeline I 10, and the temperature tracing pipeline II 11 are controlled to prevent the inert solvent or polymer solution from condensing, depositing, or clogging the pipeline. Under high-temperature cracking distillation conditions, norbornene and cyclopentadiene are produced at the top outlet of the column. The gas fraction containing most of the norbornene and cyclopentadiene enters the second distillation column 6 for further distillation and is recycled, while the polycyclopentadiene in the bottom of the column is discharged.

[0066] Example 2

[0067] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solution is 44%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 3%.

[0068] Norbornene in this embodiment is prepared through the following steps:

[0069] (1) Dicyclopentadiene, organic solvent (methylcyclohexane: toluene = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 200℃ and the pressure was increased to 9MPa. The reaction was held for 0.3h to obtain a gas-liquid mixture.

[0070] (2) Control the pressure in flash tank 4 to 600 kPa and the temperature to 80°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 16 kPa and the temperature to 90°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 13 kPa and the temperature to 100°C, distill the distillate product twice to obtain norbornene;

[0071] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 55 kPa and the temperature at 120 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0072] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 160℃; control the pressure inside the cracking tower 8 to 1300kPa and the temperature to 200℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0073] Example 3

[0074] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 40:1, the mass fraction of dicyclopentadiene in the organic solvent is 40%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 4%.

[0075] Norbornene in this embodiment is prepared through the following steps:

[0076] (1) Dicyclopentadiene, organic solvent (decane:toluene = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 240℃ and the pressure was increased to 15MPa. The reaction was held for 2 hours to obtain a gas-liquid mixture.

[0077] (2) Control the pressure in flash tank 4 to 400 kPa and the temperature to 50 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 14 kPa and the temperature to 100 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 12 kPa and the temperature to 90 °C, distill the distillate product twice to obtain norbornene;

[0078] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 60 kPa and the temperature at 130 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0079] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 170℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 180℃; control the pressure inside the cracking tower 8 to 1350kPa and the temperature to 240℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0080] Example 4

[0081] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 25:1, the mass fraction of dicyclopentadiene in the organic solvent is 45%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 10%.

[0082] Norbornene in this embodiment is prepared through the following steps:

[0083] (1) Add dicyclopentadiene, organic solvent (cyclohexane: methylcyclohexane = 1:1) and ethylene in sequence according to the ratio. Under stirring conditions, raise the temperature to 260°C and the pressure to 5MPa. Let the reaction stand for 3 hours to obtain a gas-liquid mixture.

[0084] (2) Control the pressure in flash tank 4 to 500 kPa and the temperature to 60°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 15 kPa and the temperature to 90°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 14 kPa and the temperature to 110°C, distill the distillate product twice to obtain norbornene;

[0085] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 70 kPa and the temperature at 135 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0086] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 170℃; control the pressure inside the cracking tower 8 to 1200kPa and the temperature to 180℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: diphenyl ether = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0087] Example 5

[0088] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 35:1, the mass fraction of dicyclopentadiene in the organic solvent is 30%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 9%.

[0089] Norbornene in this embodiment is prepared through the following steps:

[0090] (1) Add dicyclopentadiene, organic solvent (cyclohexane: n-dodecane = 1:1) and ethylene in sequence according to the ratio. Under stirring conditions, raise the temperature to 280°C and the pressure to 6MPa. Let the reaction stand for 1 hour to obtain a gas-liquid mixture.

[0091] (2) Control the pressure in flash tank 4 to 650 kPa and the temperature to 70 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 18 kPa and the temperature to 100 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 15 kPa and the temperature to 120 °C, distill the distillate product twice to obtain norbornene;

[0092] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 70 kPa and the temperature at 135 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0093] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 170℃; control the pressure inside the cracking tower 8 to 1200kPa and the temperature to 180℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0094] Example 6

[0095] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 40:1, the mass fraction of dicyclopentadiene in the organic solvent is 35%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 8%.

[0096] Norbornene in this embodiment is prepared through the following steps:

[0097] (1) Add dicyclopentadiene, organic solvent (cyclohexane: methylcyclohexane = 1:1) and ethylene in sequence according to the ratio. Under stirring conditions, raise the temperature to 220°C and the pressure to 10 MPa. Let the reaction stand for 7 hours to obtain a gas-liquid mixture.

[0098] (2) Control the pressure in flash tank 4 to 700 kPa and the temperature to 100 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 17 kPa and the temperature to 80 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 16 kPa and the temperature to 100 °C, distill the distillate product twice to obtain norbornene;

[0099] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 70 kPa and the temperature at 135 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0100] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 170℃; control the pressure inside the cracking tower 8 to 1200kPa and the temperature to 180℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0101] Example 7

[0102] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 20%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 7%.

[0103] Norbornene in this embodiment is prepared through the following steps:

[0104] (1) Add dicyclopentadiene, organic solvent (methylcyclohexane: n-dodecane = 1:1) and ethylene in sequence according to the ratio. Under stirring conditions, raise the temperature to 100°C and the pressure to 45 MPa. Let the reaction stand for 10 hours to obtain a gas-liquid mixture.

[0105] (2) Control the pressure in flash tank 4 to 100 kPa and the temperature to 20°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 10 kPa and the temperature to 60°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 1 kPa and the temperature to 40°C, distill the distillate product twice to obtain norbornene;

[0106] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 30 kPa and the temperature at 70 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0107] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 150℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 150℃; control the pressure inside the cracking tower 8 to 1200kPa and the temperature to 120℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: diphenyl ether = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0108] Example 8

[0109] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 25%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 6%.

[0110] Norbornene in this embodiment is prepared through the following steps:

[0111] (1) Dicyclopentadiene, organic solvent (methylcyclohexane: decane = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 100℃ and the pressure was increased to 50MPa. The reaction was held for 8 hours to obtain a gas-liquid mixture.

[0112] (2) Control the pressure in flash tank 4 to 200 kPa and the temperature to 30°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 11 kPa and the temperature to 70°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 20 kPa and the temperature to 140°C, distill the distillate product twice to obtain norbornene;

[0113] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 40 kPa and the temperature at 90 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0114] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 160℃; control the pressure inside the cracking tower 8 to 1250kPa and the temperature to 130℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0115] Example 9

[0116] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 35%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 5%.

[0117] Norbornene in this embodiment is prepared through the following steps:

[0118] (1) Dicyclopentadiene, organic solvent (n-dodecane:toluene=1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 170℃ and the pressure was increased to 35MPa. The reaction was held for 9h to obtain a gas-liquid mixture.

[0119] (2) Control the pressure in flash tank 4 to 700 kPa and the temperature to 110 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 20 kPa and the temperature to 130 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 40 kPa and the temperature to 150 °C, distill the distillate product twice to obtain norbornene;

[0120] The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 45 kPa and the temperature at 100 °C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0121] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 170℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 180℃; control the pressure inside the cracking tower 8 to 1300kPa and the temperature to 140℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0122] Example 10

[0123] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 35%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 3%.

[0124] Norbornene in this embodiment is prepared through the following steps:

[0125] (1) Dicyclopentadiene, organic solvent (decane: n-dodecane = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 400℃ and the pressure was increased to 1MPa. The reaction was allowed to proceed for 0.1h to obtain a gas-liquid mixture.

[0126] (2) Control the pressure in flash tank 4 to 800 kPa and the temperature to 120°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 19 kPa and the temperature to 110°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 30 kPa and the temperature to 130°C, distill the distillate product twice to obtain norbornene;

[0127] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 90 kPa and the temperature at 160 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0128] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 170℃; control the pressure inside the cracking tower 8 to 1350kPa and the temperature to 260℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: diphenyl ether = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0129] Example 11

[0130] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 55%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 6%.

[0131] Norbornene in this embodiment is prepared through the following steps:

[0132] (1) Dicyclopentadiene, organic solvent (cyclohexane: methylcyclohexane = 1:2) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 320°C and the pressure was increased to 2MPa. The reaction was allowed to proceed for 0.2h to obtain a gas-liquid mixture.

[0133] (2) Control the pressure in flash tank 4 to 900 kPa and the temperature to 140 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 19 kPa and the temperature to 120 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 4 kPa and the temperature to 70 °C, distill the distillate product twice to obtain norbornene;

[0134] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 95 kPa and the temperature at 170 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0135] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 150℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 180℃; control the pressure inside the cracking tower 8 to 1400kPa and the temperature to 250℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0136] Example 12

[0137] In this embodiment, the molar ratio of ethylene to dicyclopentadiene is 30:1, the mass fraction of dicyclopentadiene in the organic solvent is 60%, and the mass fraction of cyclopentadiene in the total mass fraction of cyclopentadiene and dicyclopentadiene is 2%.

[0138] Norbornene in this embodiment is prepared through the following steps:

[0139] (1) Dicyclopentadiene, organic solvent (cyclohexane:decane = 2:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 140℃ and the pressure was increased to 40MPa. The reaction was held for 8 hours to obtain a gas-liquid mixture.

[0140] (2) Control the pressure in flash tank 4 to 1000 kPa and the temperature to 160 °C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 11 kPa and the temperature to 60 °C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 7 kPa and the temperature to 50 °C, distill the distillate product twice to obtain norbornene;

[0141] The heavy component byproduct separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 100 kPa and the temperature at 180 °C. The heavy component byproduct is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0142] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 170℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 160℃; control the pressure inside the cracking tower 8 to 1400kPa and the temperature to 270℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6 for recycling.

[0143] To more intuitively illustrate the differences between Examples 1 to 12, the relevant parameter operations and operating conditions are recorded in Tables 1 and 2 below.

[0144] Table 1 Relevant Parameter Settings

[0145]

[0146] Table 2 Operating Conditions

[0147]

[0148] (Continued from Table 2: Operating Conditions)

[0149]

[0150] The calculations for Examples 1 to 12 above are performed as follows, and the calculation results are recorded in Table 3 below.

[0151] In this embodiment of the invention, the conversion rate of dicyclopentadiene (including any small amount of dicyclopentadiene contained in the raw material, all calculated as dicyclopentadiene) is defined as:

[0152] Dicyclopentadiene conversion (wt%) = ;

[0153] The selectivity of norbornene is defined as:

[0154] Selectivity of norbornene (wt%) = .

[0155] Table 3 Calculation results of data from Examples 1-12

[0156]

[0157] Based on the parameter settings and operating conditions in Tables 1 and 2 and the calculation results in Table 3, it can be seen that the conversion rate of dicyclopentadiene (DCPD) and the selectivity of norbornene (NB) using the method of producing norbornene according to the present invention are not less than 85% and not less than 94%. Therefore, it can be seen that the production method of the present invention can produce norbornene in the largest quantity, thereby improving the conversion rate of dicyclopentadiene.

[0158] The inventors used Examples 1-6 as examples, employing the following methods: Figure 2 The conventional process for preparing norbornene is shown, omitting the cracking and distillation process of the heavy component byproducts, and comparative examples 1-6 are provided.

[0159] Comparative Example 1

[0160] (1) Dicyclopentadiene, organic solvent (cyclohexane:toluene = 1:1) and ethylene were added in sequence according to the ratio. Under stirring conditions, the temperature was increased to 280°C and the pressure was increased to 3MPa. The reaction was held for 4 hours to obtain a gas-liquid mixture.

[0161] (2) Control the pressure in flash tank 4 to 300 kPa and the temperature to 40°C, separate the gas-liquid mixture, recover the washed ethylene gas, and obtain the liquid product; control the pressure in the first distillation column 5 to 13 kPa and the temperature to 80°C, distill the liquid product once to obtain the distillate product and heavy component by-product; control the pressure in the second distillation column 6 to 10 kPa and the temperature to 80°C, distill the distillate product twice to obtain norbornene.

[0162] Implementation principle: See appendix Figure 2 The prepared dicyclopentadiene and organic solvent are pumped into the feed inlet of the reaction device 3 in the DCPD / CPD tank 2. The liquid level is monitored in real time by the level gauge. When the liquid level in the reaction device 3 exceeds a certain height, the reaction device 3 starts to automatically heat and stir. The ethylene tank 1 is opened and the required ethylene is continuously introduced. The pressure is increased to 3MPa and the temperature is increased to 280℃. The mixture is kept in the reaction device 3 for 4 hours to obtain a gas-liquid mixture.

[0163] The gas-liquid mixture includes: ethylene, cyclopentadiene, dicyclopentadiene, norbornene, tetracyclododecene, polycyclopentadiene, and organic solvents.

[0164] When the liquid level in reaction device 3 is higher than 70%, the outlet of reaction device 3 is opened under motor adjustment to control the liquid level at 70%. The gas-liquid mixture in reaction device 3 flows continuously out through the outlet and into the inlet of flash tank 4;

[0165] In flash tank 4, the reaction mixture fed through the feed inlet undergoes gas-liquid separation. The separated unreacted ethylene comes into contact with the reaction solvent sprayed in the scrubbing device at the top of the tower. The solvent absorbs the unreacted cyclopentadiene and norbornene in the gas and mixes with the reaction liquid, thus completing the gas-liquid separation.

[0166] The top outlet of the flash tank 4 is the gaseous product ethylene, which is recycled back to the reaction device 3 for reuse. The bottom outlet of the flash tank 4 is the liquid product, including cyclopentadiene, dicyclopentadiene, norbornene, tetracyclododecene, polycyclopentadiene, and organic solvents.

[0167] After gas-liquid separation, the bottom outlet of flash tank 4 is opened to allow the liquid product to continuously enter the first distillation column 5, where distillation separates the fraction containing norbornene and cyclopentadiene, as well as the heavy component by-products.

[0168] The distillate product collected from the top of column 5 of the first distillation column includes: dicyclopentadiene, cyclopentadiene and norbornene; the heavy component by-product collected from the bottom of the first distillation column.

[0169] The distillate is continuously fed into the second distillation column 6, stirred and heated, and norbornene is separated by distillation. Cyclopentadiene is recovered and sent to the DCPD / CPD tank 2 for recycling.

[0170] Comparative Example 2

[0171] The difference from Example 2 is that the following is omitted: (2) The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 55 kPa and the temperature at 120°C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0172] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 160℃; control the pressure inside the cracking tower 8 to 1300kPa and the temperature to 200℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0173] Comparative Example 3

[0174] The difference from Example 3 is that the following is omitted: (2) The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 60 kPa and the temperature at 130 °C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0175] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 170℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 180℃; control the pressure inside the cracking tower 8 to 1350kPa and the temperature to 240℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0176] Comparative Example 4

[0177] The difference from Example 4 is that the following is omitted: (2) The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 70 kPa and the temperature at 135 °C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0178] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 160℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 170℃; control the pressure inside the cracking tower 8 to 1200kPa and the temperature to 180℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: diphenyl etheramine = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0179] Comparative Example 5

[0180] The difference from Example 5 is that the following is omitted: (2) The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 75 kPa and the temperature at 140 °C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0181] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 150℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 180℃; control the pressure inside the cracking tower 8 to 1400kPa and the temperature to 220℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (benzophenone: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0182] Comparative Example 6

[0183] The difference from Example 6 is that the following is omitted: (2) The heavy component by-product separated from the first distillation column 5 enters the third distillation column 7. The pressure inside the third distillation column 7 is controlled at 80 kPa and the temperature at 150 °C. The heavy component by-product is distilled in the third distillation column 7 to obtain solvent, cyclopentadiene and heavy components.

[0184] (3) Control the temperature of the inert solvent storage tank 9 and the temperature tracing pipeline I 10 to 170℃, and control the insulation temperature of the temperature tracing pipeline II 11 to 160℃; control the pressure inside the cracking tower 8 to 1280kPa and the temperature to 240℃, and control the viscosity of the bottom solution to less than 300cp by adding a high-boiling-point solvent (diphenyl ether: benzamide = 1:1) (stop the collection and replenishment when the viscosity of the bottom solution is less than 50cp), crack the heavy components and obtain norbornene and cyclopentadiene; norbornene and cyclopentadiene enter the second distillation tower 6.

[0185] To more intuitively illustrate the differences between Examples 1-6 and Comparative Examples 1-6, the relevant parameter settings and operating conditions are recorded in Table 4 below. At the same time, the DCPD conversion rate and NB selectivity are calculated according to the above calculation formula, and the calculation results are also recorded in Table 5 below.

[0186] Table 4 Relevant Parameter Settings and Operating Conditions

[0187]

[0188] Table 5 Data Calculation Results

[0189]

[0190] As can be seen from the data recorded in Table 5, in Examples 1-6, the process operation with the addition of cracking tower 8 (cracking distillation) achieved higher DCPD conversion and higher NB selectivity compared to the experimental processes in Comparative Examples 1-6. This is because in cracking tower 8, more norbornene was obtained from the heavy byproducts through heated cracking distillation, which then entered the second distillation tower and became the final product, and more dicyclopentadiene was recovered as raw material.

[0191] To further investigate the pyrolysis recovery performance of the pyrolysis tower, the inventors made Examples 13-18 by adjusting the pyrolysis heating temperature and pressure of the pyrolysis tower 8.

[0192] Example 13

[0193] The heavy component in this embodiment is derived from the bottom fraction of the third distillation column 7 in Example 3. The composition of the bottom fraction, based on its total mass of 100%, includes: norbornene 25%, tetracyclododecene 55%, cyclopentadiene 15%, polycyclopentadiene 4%, and other impurities 1%.

[0194] The heavy components were continuously fed into a 10L pyrolysis tower 8, and the pyrolysis heating temperature was adjusted to 120℃ and the pressure to 40kPa.

[0195] Example 14

[0196] The difference from Example 13 is that the heavy components are continuously fed into a pyrolysis tower 8 with a volume of 10L, and the pyrolysis heating temperature is adjusted to 200°C and the pressure is 30kPa.

[0197] Example 15

[0198] The difference from Example 13 is that the heavy components are continuously fed into a pyrolysis tower 8 with a volume of 10L, and the pyrolysis heating temperature is adjusted to 240°C and the pressure is 35kPa.

[0199] Example 16

[0200] The difference from Example 13 is that the heavy components are continuously fed into a pyrolysis tower 8 with a volume of 10L, and the pyrolysis heating temperature is adjusted to 180°C and the pressure is 20kPa.

[0201] Example 17

[0202] The difference from Example 13 is that the heavy components are continuously fed into a pyrolysis tower 8 with a volume of 10L, and the pyrolysis heating temperature is adjusted to 220°C and the pressure is 34kPa.

[0203] Example 18

[0204] The difference from Example 13 is that the heavy components are continuously fed into a pyrolysis tower 8 with a volume of 10L, and the pyrolysis heating temperature is adjusted to 270°C and the pressure is 28kPa.

[0205] To more clearly illustrate the condition parameters set in cracking column 8 in Examples 13-18, and to calculate the ratio of the recovered terpinene and cyclopentadiene in cracking column 8 of Examples 13-18 to the total mass of heavy components produced in the third distillation column, the data are recorded in Table 6 below; wherein, the proportion of recovered products is defined as:

[0206] The percentage of recovered norbornene in the total mass of the original heavy by-products (wt%) = ;

[0207] The percentage of recovered cyclopentadiene in the total mass of the original heavy by-products (wt%) = .

[0208] Table 6: Data on parameter settings and percentage of recovered products in Examples 13-18

[0209]

[0210] Based on the ratios recorded in Table 6, the inventors discovered that when cracking and distilling heavy component byproducts of the same composition, by adjusting the parameter settings of cracking tower 8, a considerable proportion of norbornene and cyclopentadiene can be recovered, thereby increasing the yield of norbornene and correspondingly reducing the yield of byproducts.

[0211] Furthermore, based on the percentage data of recovered products in Examples 13-18, the method for producing norbornene according to the present invention yields a recovered norbornene accounting for 10-48% of the total mass of the original heavy by-products, and a recovered cyclopentadiene accounting for 10-23% of the total mass of the original heavy by-products, which can save production costs.

[0212] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All modifications or applications made in accordance with the above embodiments are within the scope of protection of this technical solution.

[0213] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A method for producing norbornene, characterized in that, The method includes the following steps: S1. An organic solution of mixed ethylene and dicyclopentadiene and / or cyclopentadiene is reacted in a reaction apparatus to obtain a gas-liquid mixture product. S2. The gas-liquid mixture obtained in S1 is subjected to flash evaporation separation to recover the gaseous product and obtain the liquid product. S3. In the first distillation column, the liquid product obtained in S2 is separated by distillation to obtain distillate product and heavy component by-product; S4. In the second distillation column, the fraction from S3 is distilled again and separated to recover cyclopentadiene and obtain norbornene; at the same time, in the third distillation column, the heavy component byproduct is distilled again and separated to obtain organic solvent, cyclopentadiene and heavy component product. S5. The heavy component product obtained in S4 is fed into a cracking column for cracking and distillation, and crude norbornene product is obtained from the top outlet of the column. S6. The crude norbornene product obtained in S5 is fed to the second distillation column for distillation and purification to recover cyclopentadiene and obtain norbornene.

2. The method for producing norbornene according to claim 1, characterized in that, In S1, the organic solvent of the organic solution is selected from one or more of cycloalkanes, alkanes, and aromatic organic solvents.

3. The method for producing norbornene according to claim 2, characterized in that, In S1, the organic solvent of the organic solution is selected from one or more of cyclohexane, methylcyclohexane, decane, n-dodecane, and toluene.

4. The method for producing norbornene according to claim 1, characterized in that, In S1, the molar ratio of ethylene to dicyclopentadiene and / or cyclopentadiene is (20~40):1, wherein dicyclopentadiene is converted to cyclopentadiene according to the molar ratio, and is calculated as cyclopentadiene; the mass fraction of dicyclopentadiene and / or cyclopentadiene in the organic solution is 20~60wt.

5. The method for producing norbornene according to claim 4, characterized in that, In S1, the molar ratio of ethylene to dicyclopentadiene and / or cyclopentadiene is (25~35):1, wherein dicyclopentadiene is converted to cyclopentadiene according to the molar ratio, and is calculated as cyclopentadiene; the mass fraction of dicyclopentadiene and / or cyclopentadiene in the organic solution is 30~50wt.

6. The method for producing norbornene according to claim 1, characterized in that, In S1, when both dicyclopentadiene and cyclopentadiene are used as raw materials, the mass fraction of cyclopentadiene is 2-10 wt%.

7. The method for producing norbornene according to claim 1, characterized in that, In S1, the reaction temperature is 100~400℃, the reaction pressure is 1~50MPa, and the reaction residence time is 0.1~10h.

8. The method for producing norbornene according to claim 7, characterized in that, In S1, the reaction temperature is 200~280℃, the reaction pressure is 3~15MPa, and the reaction residence time is 0.3~4h.

9. The method for producing norbornene according to claim 1, characterized in that, In S2, the separation temperature is 20~160℃ and the separation pressure is 100~1000kPa.

10. The method for producing norbornene according to claim 9, characterized in that, In S2, the separation temperature is 40~100℃ and the separation pressure is 300~700kPa.

11. The method for producing norbornene according to claim 1, characterized in that, In S3, the bottom temperature of the first distillation column is 60~130℃, and the distillation pressure is 10~20kPa.

12. The method for producing norbornene according to claim 11, characterized in that, In S3, the bottom temperature of the first distillation column is 80~100℃, and the distillation pressure is 13~18kPa.

13. The method for producing norbornene according to claim 1, characterized in that, In S4, the bottom temperature of the second distillation column is 40~150℃ and the distillation pressure is 1~40kPa; the bottom temperature of the third distillation column is 70~180℃ and the distillation pressure is 30~100kPa.

14. The method for producing norbornene according to claim 13, characterized in that, In S4, the bottom temperature of the second distillation column is 80~120℃ and the distillation pressure is 10~16kPa; the bottom temperature of the third distillation column is 110~150℃ and the distillation pressure is 50~80kPa.

15. The method for producing norbornene according to claim 1, characterized in that, In S5, the temperature of the bottom of the cracking tower is 120~270℃, and the pressure of the cracking distillation is 1200~1400kPa.

16. The method for producing norbornene according to claim 15, characterized in that, In S5, the temperature of the bottom of the cracking tower is 160~240℃, and the pressure of the cracking distillation is 1250~1350kPa.

17. The method for producing norbornene according to claim 1, characterized in that, In step S5, the pyrolysis reaction of the heavy component products is carried out using a solution method.

18. The method for producing norbornene according to claim 17, characterized in that, The solvent used in the solution method is a solvent with a boiling point higher than 250°C.

19. The method for producing norbornene according to claim 18, characterized in that, The solvent of the solution is selected from one or more of benzophenone, diphenyl ether, and benzamide.

20. The method for producing norbornene according to claim 1 or 18, characterized in that, The solvent is insulated in an inert solvent storage tank, which is connected to the pyrolysis tower via a temperature tracing pipeline I; the temperature of both the inert solvent storage tank and the temperature tracing pipeline I is set to 150~170℃.

21. The method for producing norbornene according to claim 1, characterized in that, In S5, the bottom product of the pyrolysis tower is an intermittent process. When the viscosity of the bottom solution is greater than 300 cp, product is started and a high-boiling-point solvent is added; when the viscosity of the bottom solution is less than 50 cp, product is stopped and the high-boiling-point solvent is added.

22. The method for producing norbornene according to claim 1, characterized in that, In S5, a temperature tracing pipeline II is provided at the outlet of the pyrolysis tower; the temperature of the temperature tracing pipeline II is set to 150~180℃.

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