WO2024139679A1 - Production process for norbornene - Google Patents

Abstract

The present invention relates to the field of organic chemical engineering. Disclosed is a production process for norbornene. The production process comprises the following steps: (1) pre-dissolving ethylene gas in an inert solvent; and (2) feeding the inert solvent, in which ethylene is pre-dissolved, and a dicyclopentadiene solution into an N-stage series-connected reaction kettle for reaction, so as to obtain norbornene, wherein N is greater than or equal to 3, and the reaction conditions comprise: a pressure of 1-15 MPa, a temperature of 160-280ºC, and a total retention time of 3-120 min. The present invention provides a method for producing norbornene; in addition, partition control over dicyclopentadiene depolymerization and Diels-Alder reaction is achieved by means of a homogeneous process and a multi-kettle series connection method, such that the aims of inhibiting side reactions, and improving reaction selectivity, thereby obtaining high-yield and high-selectivity norbornene are achieved.

Description

Production process of norbornene

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Chinese patent application 202211677126.3 filed on December 26, 2022, the contents of which are incorporated herein by reference.

Technical Field

The invention relates to the field of organic chemical industry, and in particular to a production process of norbornene.

Background technique

Norbornene, also known as Norbornene in English, abbreviated as NB, has the chemical name of bicyclo[2.2.1]-2-heptene, molecular formula C7H10, relative molecular mass 94.16, boiling point 96°C, melting point 44-46°C, flash point -15°C, density 0.950g/cm3, refractive index 1.4475, and is a white translucent crystal at room temperature that is easy to sublime.

More than 97% of the world's norbornene products are used for the synthesis of cycloolefin copolymers/polymers COC/COP. Cyclic olefin polymers have the advantages of low density, low hygroscopicity, high transparency, high heat resistance, high refractive index and excellent processability. They are amorphous thermoplastic polymer materials that have attracted great attention in industry and academia in recent years.

Since Joshel et al. first reported the synthesis reaction of NB in 1941, there have been continuous patents and literature reports on the development and research of NB synthesis process. In industry, ethylene and cyclopentadiene (CPD) are used to synthesize norbornene through the Diels-Alder reaction. The reaction equation is as follows:

Since ethylene does not contain electron-withdrawing substituents, when it acts as a dienophile to undergo a Diels-Alder reaction, the reaction is difficult due to the large energy level difference between matching orbitals. At present, the compensation methods for the insufficient reactivity of ethylene can be summarized into two categories: one is to increase the pressure, which is a thermodynamically and kinetically favorable factor (actually increasing the molar ratio of ethylene//CPD); the other is to increase the temperature, which is kinetically favorable but thermodynamically unfavorable (the reaction between CPD and dienophile is an exothermic reaction). Therefore, the traditional synthesis of norbornene needs to be carried out at high temperature and high pressure, which is close to the thermal decomposition conditions of polycyclopentadiene, and has great safety risks in production.

Since dicyclopentadiene has conjugated double bonds, it is active in nature and is very prone to dimerization. Commercial cyclopentadiene exists in the form of dicyclopentadiene. When dicyclopentadiene is used as a raw material to prepare norbornene, dicyclopentadiene needs to be depolymerized. The depolymerization of dicyclopentadiene is an endothermic reaction, while the reaction for producing norbornene is an exothermic reaction. At the same time, under heating conditions, dicyclopentadiene is very prone to polymerization to generate insoluble resins. The polymer precipitation of dicyclopentadiene is adsorbed on the inner wall of the reactor, and coking and carbon deposition at high temperature block the reaction pipeline, affecting the stability and safety of the long-term operation of the production unit and the technical and economic performance.

The processes suitable for the industrial production of norbornene and its derivatives can be divided into two types: liquid phase reaction process and gas phase reaction process. In the liquid phase reaction process, CPD or DCPD is in liquid state during the reaction, and ethylene gas is dissolved in the liquid phase for addition reaction; in the gas phase reaction process, CPD or DCPD is first heated to gasify it, and then mixed with ethylene gas and introduced into the reactor for reaction.

US3007977 discloses a method for producing norbornene (NB) by a liquid phase solvent-free, intermittent reaction process. The reaction temperature of the reaction zone is controlled by changing the ratio of cyclopentadiene and dicyclopentadiene in the raw materials, and ethylene is liquefied by high pressure to achieve the reaction in the liquid phase. The raw materials are preheated at 130-220°C and then fed. The reaction temperature is 150-250°C, the pressure is 500-10000 psig, and the reaction time is up to 23 hours. The solvent-free liquid phase reaction process has the disadvantage of serious side reactions, easy to produce polymers or polymers, and cause blockage of the reactor and related equipment.

US3766283 reports a method for synthesizing norbornene using an upflow fixed bed process. Cyclopentadiene is diluted with an inert solvent (the inert solvent used is a mixture of o-, m-, and p-xylene in different proportions), and a reaction is carried out in the presence of an inert solvent to prepare norbornene. The solvent used is an inert solvent with a boiling point higher than 100°C. Pyrex glass balls of a certain size are loaded into the stainless steel fixed bed reactor to improve the gas-liquid mixing effect, and ethylene is injected from the bottom of the reactor with cyclopentadiene using a pressure cylinder. The molar ratio of ethylene/dicyclopentadiene added to the reactor ranges from 1:0.5 to 10:1, the reaction temperature is 200 to 325°C, the pressure is 100 to 2000 psig, and the reaction time is 0.4 to 5h. The conversion rate of dicyclopentadiene in this process can reach more than 97%, and the selectivity of norbornene can reach up to 89.8%. The solvent reaction process reduces the production of polymers by diluting cyclopentadiene, but it is necessary to increase the concentration of ethylene in the liquid phase under high pressure. Medium solubility, harsh reaction conditions and long reaction time.

US4168282 and CA1215399 screened and optimized inert solvents, respectively, and disclosed a method for inhibiting the resinification of dicyclopentadiene by using halogenated hydrocarbons (especially chlorinated hydrocarbons) as inert solvents and diluting dicyclopentadiene with inert aliphatic solvents (n-pentane, n-hexane, n-heptane, cyclohexane, etc., and mixtures thereof) to achieve the purpose of inhibiting its resinification and improving selectivity.

DE215078 discloses a method for producing norbornene using a gas phase reaction process. CPD is reacted with ethylene in the gas phase. Compared with the liquid phase reaction process, the materials in the gas phase reaction process are mixed more fully, which greatly curbs the occurrence of side reactions. However, since the reactants and products of the gas phase reaction process are in the gas phase state, the molar volume is greatly increased. Due to the constraints of the reactor volume and processing capacity, the residence time of the gas phase process is greatly shortened compared with the liquid phase process. Although the reaction temperature is about 100°C higher than that of the liquid phase process, its final DCPD conversion rate is still relatively low.

CN105481625A discloses a method for preparing norbornene (NB) using dicyclopentadiene (DCPD) and ethylene as raw materials, using methyl isobutyl ketone (MIBK) as solvent, using a two-kettle series process, first depolymerizing dicyclopentadiene (DCPD) into cyclopentadiene (CPD), and then converting cyclopentadiene (CPD) into norbornene through Diels-Alder reaction with ethylene. This method makes full use of the heat balance of DCPD depolymerization endothermic and diene synthesis exothermic, and has certain economy and safety, but does not solve the problem of full mixed kettle process, the residence time distribution of reactants is relatively wide, resulting in the accumulation of polymers in the kettle as the reaction cycle is extended, affecting the long-term stable operation of the device. At the same time, the process adds an inhibitor to suppress the generation of polymers, and the addition of the inhibitor will affect the catalysis of norbornene participating in the metallocene polymerization reaction in the later stage. The agent is active and must be removed before the polymerization reaction, which increases the complexity of the process and the operating cost.

CN104692993A discloses a method for synthesizing norbornene by a microchannel reactor, the microchannel reactor comprises a reaction section, the reaction channel of the reaction section is provided with two or more feed ports along the flow direction of the material, comprising the following steps: feeding a dicyclopentadiene solution into the reaction channel of the reaction section from any one of the feed ports, feeding ethylene into the reaction channel of the reaction section from the first feed port, the reaction temperature in the reaction channel is 180°C-300°C, the pressure is 5-30MPa, the residence time of the reaction section is 0.5-10 minutes, and the molar ratio of ethylene to the dicyclopentadiene solution is 1-10:1. However, the microchannel is a homogeneous reactor, and ethylene needs to be liquefied under high pressure, and the reaction conditions are relatively harsh.

CN104262074A discloses a method for preparing norbornene by reacting cyclopentadiene generated in situ with ethylene, wherein hydrogen is introduced to suppress the multipolymers generated during the reaction of dicyclopentadiene cracking to generate cyclopentadiene, so as to increase the yield of cyclopentadiene and extend the operation cycle of the device. The method can shorten the reaction time to less than 10 seconds, but the reaction conditions are harsh, the reaction temperature is above 300°C, and the reaction pressure is above 20MPa. At the same time, the problem of multipolymer generation caused by backmixing during the reaction of preparing norbornene is not solved.

CN109293677B discloses a method for preparing 7-amino-3-vinyl cephalosporanic acid by a tandem reaction process. The multi-stage tandem reactor system includes four or more stage-type reactors connected in series. Although the temperatures between different reactors can be independently controlled, the process is operated in series by overflow, and the pressure of each reactor is the same, and it is impossible to achieve independent pressure control. When the process is used to prepare norbornene, polymers will gradually accumulate and increase as the reaction proceeds, and high temperature and high pressure may cause polymer cracking and explosion.

Summary of the invention

The purpose of the present invention is to overcome the problems existing in the prior art and provide a production process for norbornene. The production process provided by the present invention realizes the partition control of dicyclopentadiene depolymerization and Diels-Alder reaction through a homogeneous process and a multi-reactor series method, thereby suppressing the occurrence of side reactions and improving the reaction selectivity, thereby obtaining norbornene with high yield and high selectivity.

In order to achieve the above object, the present invention provides a production process of norbornene, which process comprises the following steps:

(1) pre-dissolving ethylene gas in an inert solvent;

(2) feeding the inert solvent in which ethylene is pre-dissolved and the dicyclopentadiene solution into a reactor including N stages connected in series to react and obtain norbornene, wherein N≥3;

The reaction conditions include: pressure of 1-15 MPa, temperature of 160-280° C., and total residence time of 3-120 min.

Through the above technical solution, the beneficial effects of the present invention include:

The production process of the present invention uses an inert solvent in which ethylene is pre-dissolved and a dicyclopentadiene solution as raw materials, ensures that there is no gas phase space in the reactor, so as to achieve the purpose of liquid-liquid homogeneous reaction, and adopts N-stage reactor series technology to realize the partition control of dicyclopentadiene depolymerization and cycloaddition reaction with ethylene, and independently controls the temperature, pressure and residence time of each reactor, so that the reaction is carried out under a real-time material system and reasonable working conditions, so as to realize precise control of the reaction process, effectively inhibit the occurrence of side reactions, and improve the reaction selectivity, thereby obtaining high-yield and high-selectivity norbornene. It also reduces the probability of insoluble resin generation and improves Long-term stability and safety of the technology for preparing norbornene.

The present invention adopts N-stage reactor series connection technology to achieve the purpose of liquid-liquid homogeneous plug flow reaction, significantly reduces the reaction time and improves the reaction efficiency.

The process production provided by the present invention can achieve excellent dicyclopentadiene conversion rate and norbornene selectivity. The dicyclopentadiene conversion rate can reach up to 99.7%, and the norbornene selectivity can reach up to 99.8%.

The production process provided by the present invention reduces the severity of the reaction, significantly reduces the reaction time, improves the reaction efficiency, does not need to add a polymerization inhibitor, has a simple preparation process, improves the production efficiency, and is economical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of the production process of the present invention;

FIG. 2 is a schematic diagram of six-stage series reactors in the production process of norbornene provided by the present invention.

Detailed ways

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

In the absence of special instructions, the "reaction pressure" and "tower pressure" mentioned in the present invention are All are absolute pressures.

In one aspect, the present invention provides a process for producing norbornene, the process comprising the following steps:

(1) pre-dissolving ethylene gas in an inert solvent;

(2) feeding the inert solvent in which ethylene is pre-dissolved and the dicyclopentadiene solution into a reactor including N stages connected in series to react and obtain norbornene, wherein N≥3;

The reaction conditions include: pressure of 1-15 MPa, temperature of 160-280° C., and total residence time of 3-120 min.

In the N-stage series-connected reactor of the present invention, the reaction discharge of the previous stage is used as the reaction feed of the next stage.

In the existing technology for preparing norbornene, a single autoclave reactor (full mixed flow reactor) is mostly used, which has the advantages of simple process and easy operation. However, a single autoclave reactor does not solve the problem of residence time distribution of reactants. Under this condition, as dicyclopentadiene accumulates in the reaction system, it is very easy to undergo polymerization to generate insoluble resin, which seriously reduces the reaction selectivity and affects the stability of the long-term operation of the production unit. At the same time, in order to overcome the reaction capacity and enhance the dissolution of ethylene, the reaction is usually carried out at high temperature (250-340°C) and high pressure (15-35MPa). Insoluble resins under high temperature and high pressure are prone to cracking and cause the risk of explosion, and have great safety hazards in production. The production process of the present invention uses an inert solvent in which ethylene is pre-dissolved and a dicyclopentadiene solution as raw materials to ensure that there is no gas phase space in the reactor to achieve the purpose of homogeneous reaction. At the same time, an N-stage reactor in series is used, which is close to a plug flow process. It has both the full mixed flow reaction characteristics of an autoclave reactor and can effectively overcome the problem of residence time distribution of reactants. The reaction is carried out under low temperature and low pressure conditions, while shortening the residence time. It effectively reduces the probability of side reactions and improves reaction selectivity, thereby obtaining high-yield and high-selectivity norbornene. It also improves the long-term stability and safety of norbornene preparation technology and realizes the continuous preparation of norbornene.

According to the present invention, preferably, 3≤N≤10, preferably 3≤N≤6. For example, 3, 4, 5, 6, 7, 8, 9, 10. When the N value is greater than the range described in the present invention, the increase in the number of reactors has little effect on the beneficial effects of the reaction, but the increase in production costs is large, which is not conducive to industrial application. When the N value is less than the range described in the present invention, dicyclopentadiene is very likely to undergo side reactions to generate insoluble resins, which seriously reduces the reaction selectivity.

According to the present invention, preferably, the reaction conditions include: a pressure of 1-12 MPa, such as 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, and any value in the range formed by any two of these values; a temperature of 180-250°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, and any value in the range formed by any two of these values; a total residence time of 6-60 min, such as 6 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, and any value in the range formed by any two of these values.

According to the present invention, preferably, the reaction temperature of the subsequent reactor is not higher than the reaction temperature of the previous reactor.

According to the present invention, preferably, the reaction temperature of the subsequent reactor is 5-60°C lower than the reaction temperature of the previous reactor, preferably 10-50°C lower, such as 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, and any value in the range formed by any two of these values. It is beneficial to inhibit the polymerization of oligomers and improve the reaction selectivity. When it is lower than this range, the yield of norbornene decreases; when it is higher than this range, the selectivity of dicyclopentadiene decreases.

According to the present invention, preferably, the reaction pressure of the subsequent reactor is not higher than the reaction pressure of the previous reactor.

According to the present invention, preferably, the reaction pressure of the latter reactor is 0.5-4MPa lower than the reaction pressure of the former reactor, preferably 1-2MPa, such as 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, and any value in the range formed by any two of these values. The use of this preferred embodiment is conducive to improving the reaction selectivity, while effectively avoiding the risk of explosion of insoluble resins and reducing safety hazards in production. When it is lower than this range, the yield of norbornene is reduced; when it is higher than this range, the energy consumption will increase significantly, which is not conducive to industrial application.

According to the present invention, preferably, the residence time of each stage of the reactor is independently 1-40min, preferably 2-20min, such as 1min, 2min, 4min, 6min, 8min, 10min, 12min, 14min, 16min, 18min, 20min, 22min, 24min, 26min, 28min, 30min, 32min, 34min, 36min, 38min, 40min, and any value in the range formed by any two of these values. By adopting this preferred embodiment, the residence time of each stage of the reactor is shortened, which is conducive to improving the selectivity of norbornene.

According to the present invention, preferably, the residence time of the first-stage reactor is not less than 8 minutes, preferably 10-20 minutes, such as 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, 20 minutes, and any value in the range formed by any two of these values. This preferred embodiment is adopted to achieve the effect of improving the full cracking of dicyclopentadiene into cyclopentadiene, promoting the reaction of cyclopentadiene and ethylene, and providing an ethylene environment to inhibit the formation of polymers.

According to the present invention, preferably, the molar ratio of dicyclopentadiene to ethylene is 1-20:1, preferably 1-15:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, and any value in the range formed by any two of these values. By adopting this preferred embodiment, the selectivity and economy of the reaction can be improved.

According to the present invention, preferably, the pre-dissolution conditions include: a temperature of 20-80°C, preferably 30-60°C; and a pressure of 2-8MPa, preferably 3-6MPa.

The present invention has a wide range of selection for the types of the inert solvent and the solvent in the dicyclopentadiene solution. Preferably, the inert solvent and the solvent in the dicyclopentadiene solution are each independently selected from C ₆ -C ₁₂ alkanes, C ₇ -C ₉ aromatic hydrocarbons, polar solvents containing carbonyl functional groups and/or amide functional groups, preferably at least one selected from cyclohexane, n-decane, toluene, xylene and N,N-dimethylformamide.

The present invention has no particular limitation on the amount of the inert solvent, as long as the solubility of ethylene in the inert solvent is lower than the solubility of ethylene in the reaction solution during the reaction.

According to the present invention, preferably, the solubility of ethylene pre-dissolved in the inert solvent is lower than the solubility of ethylene in the reaction solution during the reaction. This preferred embodiment is adopted to ensure that the reaction system has no gas phase space, which is conducive to achieving the purpose of homogeneous reaction.

In the present invention, the solvent in the dicyclopentadiene solution can be reused after being recovered.

In the present invention, the inert solvent may be the same as or different from the solvent in the dicyclopentadiene solution. Preferably, the inert solvent is the same as the solvent in the dicyclopentadiene solution.

According to the present invention, preferably, the mass fraction of dicyclopentadiene in the dicyclopentadiene solution is 10-85%, preferably 20-75%.

In the cyclopentadiene product, cyclopentadiene mainly exists in the form of dicyclopentadiene. Although there is a small amount of cyclopentadiene, in the present invention, since dicyclopentadiene is basically converted into cyclopentadiene and reacts with ethylene after passing through the preheating unit and the first-stage reactor, the content of cyclopentadiene in the cyclopentadiene product has basically no effect on the reaction of the present invention. The present invention does not have any special limitation on cyclopentadiene, and all are calculated as dicyclopentadiene.

According to the present invention, preferably, the content of dicyclopentadiene polymers in the effluent of the last stage reactor is 0.01-0.3 wt %, preferably 0.01-0.2 wt %.

According to the present invention, preferably, the flow direction of the materials in each stage of the reaction kettle is upward in and downward out. This preferred embodiment is conducive to improving liquid-liquid mass transfer.

According to the present invention, preferably, the process further comprises: before the dicyclopentadiene solution is introduced into the first-stage reaction kettle, the dicyclopentadiene solution is first preheated.

According to the present invention, preferably, the first preheating temperature is 100-300° C., preferably 120-250° C. By adopting this preferred embodiment, the advance preheating of dicyclopentadiene can accelerate the cracking time of dicyclopentadiene in the reactor, increase the reaction rate, and reduce the residence time of the material in the reactor, thereby achieving the purpose of improving the reaction selectivity.

According to the present invention, preferably, the process further comprises: before the inert solvent in which ethylene is pre-dissolved is introduced into the first-stage reactor, a second preheating of the inert solvent in which ethylene is pre-dissolved is performed.

According to the present invention, preferably, the second preheating temperature is 100-280° C., preferably 150-240° C. This preferred embodiment is beneficial to improving the reaction rate.

According to the present invention, preferably, the process further comprises: The products are separated to obtain ethylene gas and a liquid mixture containing norbornene.

The present invention has no particular limitation on the separation method, and the separation can be carried out by commonly used technical means in the art. The present invention preferably adopts the flash evaporation method.

The present invention has no particular limitation on the specific conditions of flash evaporation, which can be carried out according to conventional methods in the art, and the present invention will not elaborate on them here.

Preferably, the ethylene gas is recycled.

According to the present invention, preferably, the liquid phase mixture containing norbornene is purified to obtain norbornene. This preferred embodiment is conducive to obtaining high-purity norbornene.

The present invention has no particular limitation on the purification method, and the purification can be carried out by commonly used technical means in the art. Preferably, the purification is carried out by distillation.

Preferably, the distillation conditions include: tower top temperature 46-50° C., tower pressure 0.1-0.3 bar, and reflux ratio 8-12:1.

The present invention will be described in detail below through examples.

In the following examples, the dicyclopentadiene content was measured by gas chromatography;

Conversion rate of dicyclopentadiene = (mass of dicyclopentadiene in the raw material - mass of dicyclopentadiene in the product) / mass of dicyclopentadiene in the raw material;

Selectivity of norbornene = mass of dicyclopentadiene consumed in producing norbornene/mass of dicyclopentadiene converted.

The reagents used in the following examples are commercially available and of analytical grade.

In the following examples, the distillation was carried out at a tower top temperature of 46°C, a tower pressure of 0.2 bar, and a reflux The ratio is 10:1.

Example 1

The process of the present invention will now be described in detail with reference to FIG1 .

A three-reactor series process is adopted. A 20% dicyclopentadiene solution is prepared with cyclohexane as solvent and injected into the preheater at a preheating temperature of 120°C; the molar ratio of ethylene to dicyclopentadiene is 15:1, ethylene is dissolved in the cyclohexane solution at 30°C and 6MPa, and injected into the preheater at a preheating temperature of 150°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 230°C, a reaction pressure of 12MPa, and a residence time of 20 minutes; enter the second-stage reactor, with a reaction temperature of 220°C, a reaction pressure of 10MPa, and a residence time of 10 minutes; enter the third-stage reactor, with a reaction temperature of 180°C, a reaction pressure of 8MPa, and a residence time of 6 minutes. The flow direction of the materials in each stage of the reactor is from top to bottom. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.01% by weight. The effluent of the last stage reactor is flashed to obtain a liquid mixture of ethylene gas and norbornene. The ethylene is recovered and reused. The liquid phase mixture containing norbornene is sampled and analyzed by chromatography, and then distilled by a distillation tower to obtain norbornene with a purity greater than 99.9%.

Example 2

The six-reactor series process is adopted, as shown in Figure 2. A 50% dicyclopentadiene solution is prepared with decane as the solvent and injected into the preheater at a preheating temperature of 250°C. The molar ratio of ethylene to dicyclopentadiene is 5:1. Ethylene is dissolved in the decane solution at 60°C and 3MPa and injected into the preheater at a preheating temperature of 240°C. After preheating, the two streams of materials enter The first stage reactor has a reaction temperature of 250°C, a reaction pressure of 11MPa, and a residence time of 20 minutes; the second stage reactor has a reaction temperature of 240°C, a reaction pressure of 10MPa, and a residence time of 10 minutes; the third stage reactor has a reaction temperature of 230°C, a reaction pressure of 8MPa, and a residence time of 5 minutes; the fourth stage reactor has a reaction temperature of 220°C, a reaction pressure of 6MPa, and a residence time of 8 minutes; the fifth stage reactor has a reaction temperature of 210°C, a reaction pressure of 4MPa, and a residence time of 6 minutes; the sixth stage reactor has a reaction temperature of 180°C, a reaction pressure of 4MPa, and a residence time of 2 minutes; the flow direction of the materials in each stage reactor is from top to bottom. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.05% by weight. The effluent of the last stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a rectification tower to obtain norbornene with a purity greater than 99.9%.

Example 3

A four-reactor series process is adopted. A dicyclopentadiene solution with a mass fraction of 75% is prepared with toluene as the solvent and injected into the preheater with a preheating temperature of 180°C; the molar ratio of ethylene to dicyclopentadiene is 10:1, ethylene is dissolved in the toluene solution at 40°C and 4MPa, and injected into the preheater with a preheating temperature of 190°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 250°C, a reaction pressure of 10MPa, and a residence time of 20 minutes; enter the second-stage reactor, with a reaction temperature of 240°C, a reaction pressure of 8MPa, and a residence time of 10 minutes; enter the third-stage reactor, with a reaction temperature of 230°C, a reaction pressure of 6MPa, and a residence time of 5 minutes; enter the fourth-stage reactor, with a reaction temperature of 180°C, a reaction pressure of 4MPa, and a residence time of 2 minutes; the flow direction of the materials in each stage of the reactor is from top to bottom. The last one The content of dicyclopentadiene polymer in the effluent of the first-stage reactor is 0.1% by weight. The effluent of the last-stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid phase mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a distillation tower to obtain norbornene with a purity greater than 99.9%.

Example 4

A five-reactor series process is adopted. A 10% dicyclopentadiene solution is prepared with toluene as solvent and injected into the preheater at a preheating temperature of 100°C; the molar ratio of ethylene to dicyclopentadiene is 1:1, ethylene is dissolved in a toluene solution at 50°C and 5MPa, and injected into the preheater at a preheating temperature of 100°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 280°C, a reaction pressure of 9MPa, and a residence time of 1 minute; enter the second-stage reactor, with a reaction temperature of 240°C, a reaction pressure of 8MPa, and a residence time of 5 minutes; enter the third-stage reactor, with a reaction temperature of 230°C, a reaction pressure of 6MPa, and a residence time of 10 minutes; enter the fourth-stage reactor, with a reaction temperature of 220°C, a reaction pressure of 4MPa, and a residence time of 20 minutes; enter the fifth-stage reactor, with a reaction temperature of 210°C, a reaction pressure of 1MPa, and a residence time of 30 minutes; the flow direction of the materials in each stage of the reactor is from top to bottom. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.25% by weight. The effluent of the last stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid phase mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a distillation tower to obtain norbornene with a purity greater than 99.9%.

Example 5

The six-reactor series process is adopted. A 30% dicyclopentadiene solution is prepared with N, N-dimethylformamide as solvent and injected into the preheater at a preheating temperature of 300°C; the molar ratio of ethylene to dicyclopentadiene is 3:1, ethylene is dissolved in the N, N-dimethylformamide solution at 50°C and 5MPa, and then injected into the preheater at a preheating temperature of 120°C. After preheating, the two streams of materials enter the first stage reactor respectively, with a reaction temperature of 280°C, a reaction pressure of 12MPa, and a residence time of 1 minute; enter the second stage reactor, with a reaction temperature of 240°C, a reaction pressure of 10MPa, and a residence time of 5 minutes; enter the third stage reactor, with a reaction temperature of 230°C, a reaction pressure of 8MPa, and a residence time of 10 minutes; enter the fourth stage reactor, with a reaction temperature of 220°C, a reaction pressure of 6MPa, and a residence time of 15 minutes; enter the fifth stage reactor, with a reaction temperature of 215°C, a reaction pressure of 5MPa, and a residence time of 20 minutes; enter the sixth stage reactor, with a reaction temperature of 180°C, a reaction pressure of 4MPa, and a residence time of 25 minutes; the flow direction of the materials in each stage of the reactor is from top to bottom. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.3% by weight. The effluent of the last stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a rectification tower to obtain norbornene with a purity greater than 99.9%.

Example 6

The six-reactor series process is adopted. A 50% dicyclopentadiene solution is prepared with decane as the solvent and injected into the preheater at a preheating temperature of 250°C. The molar ratio of ethylene to dicyclopentadiene is 5:1. Ethylene is dissolved in the decane solution at 30°C and 6MPa and injected into the preheater at a preheating temperature of 240°C. After preheating, the two streams of materials enter the first stage Reactor, reaction temperature 280 ℃, reaction pressure 12MPa, residence time 1 minute; enter the second stage reactor, reaction temperature 240 ℃, reaction pressure 10MPa, residence time 5 minutes; enter the third stage reactor, reaction temperature 230 ℃, reaction pressure 8MPa, residence time 10 minutes; enter the fourth stage reactor, reaction temperature 220 ℃, reaction pressure 6MPa, residence time 15 minutes; enter the fifth stage reactor, reaction temperature 215 ℃, reaction pressure 5MPa, residence time 20 minutes; enter the sixth stage reactor, reaction temperature 180 ℃, reaction pressure 4MPa, residence time 25 minutes; the flow direction of materials in each stage reactor is up in and down out. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.28% by weight. The effluent of the last stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a rectification tower to obtain norbornene with a purity greater than 99.9%.

Comparative Example 1

A single-kettle process is adopted. A dicyclopentadiene solution with a mass fraction of 75% is prepared with toluene as the solvent and injected into the preheater with a preheating temperature of 180°C; the molar ratio of ethylene to dicyclopentadiene is 10:1, ethylene is dissolved in the toluene solution at 40°C and 4MPa, and injected into the preheater with a preheating temperature of 190°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 250°C, a reaction pressure of 10MPa, and a residence time of 20 minutes. The content of dicyclopentadiene polymer in the effluent of the reactor is 4.9% by weight. The effluent of the reactor is flash evaporated to obtain ethylene gas and a liquid mixture containing norbornene. The ethylene is recovered and reused. The liquid mixture containing norbornene is sampled and analyzed by chromatography, and then refined. The product is distilled in a distillation tower to obtain norbornene with a purity greater than 99.9%.

Comparative Example 2

A two-kettle series process is adopted. A dicyclopentadiene solution with a mass fraction of 75% is prepared with toluene as the solvent and injected into the preheater at a preheating temperature of 180°C; the molar ratio of ethylene to dicyclopentadiene is 10:1, ethylene is dissolved in the toluene solution at 40°C and 4MPa, and injected into the preheater at a preheating temperature of 190°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 250°C, a reaction pressure of 10MPa, and a residence time of 20 minutes; and enter the second-stage reactor, with a reaction temperature of 240°C, a reaction pressure of 8MPa, and a residence time of 10 minutes. The content of dicyclopentadiene polymer in the effluent of the second-stage reactor is 3.7% by weight. The effluent of the second-stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. Ethylene is recovered and reused. The liquid phase mixture containing norbornene is sampled and analyzed by chromatography, and then rectified by a distillation tower to obtain norbornene with a purity greater than 99.9%.

Comparative Example 3

A four-reactor series process is adopted. A 75% dicyclopentadiene solution is prepared with toluene as the solvent and injected into the preheater with a preheating temperature of 180°C; the molar ratio of ethylene to dicyclopentadiene is 10:1, and ethylene is measured in the form of gas through a gas mass flowmeter and injected into the preheater with a preheating temperature of 190°C. After preheating, the two streams of materials enter the first-stage reactor respectively, with a reaction temperature of 250°C, a reaction pressure of 10MPa, and a residence time of 20 minutes; enter the second-stage reactor, with a reaction temperature of 240°C, a reaction pressure of 8MPa, and a residence time of 10 minutes; enter the third-stage reactor, with a reaction temperature of 230°C, a reaction pressure of 6MPa, and a residence time of 5 minutes; Enter the fourth stage reactor, the reaction temperature is 180°C, the reaction pressure is 4MPa, and the residence time is 2 minutes; the flow direction of the materials in each stage reactor is from top to bottom. The content of dicyclopentadiene polymer in the effluent of the last stage reactor is 0.15% by weight. The effluent of the last stage reactor is flashed to obtain ethylene gas and a liquid phase mixture containing norbornene. The ethylene is recovered and reused. The liquid phase mixture containing norbornene is sampled and analyzed by chromatography, and then distilled by a distillation tower to obtain norbornene with a purity greater than 99.9%.

Table 1

It can be seen from the results in Table 1 that the production process of the present invention for preparing norbornene has significantly higher dicyclopentadiene conversion rate and norbornene selectivity.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including combining various technical features in any other suitable manner. Simple variations and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (10)

1. A production process of norbornene, characterized in that the process comprises the following steps:

   (1) pre-dissolving ethylene gas in an inert solvent;

   (2) feeding the inert solvent in which ethylene is pre-dissolved and the dicyclopentadiene solution into a reactor including N stages connected in series to react and obtain norbornene, wherein N≥3;

   The reaction conditions include: pressure of 1-15 MPa, temperature of 160-280° C., and total residence time of 3-120 min.
2. The process according to claim 1, wherein 3≤N≤10;

   And/or, the reaction conditions include: pressure of 1-12 MPa, temperature of 180-250° C., and total residence time of 6-60 min.
3. The process according to claim 1, wherein

   The reaction temperature of the next stage reactor is not higher than the reaction temperature of the previous stage reactor;

   And/or, the reaction pressure of the subsequent reactor is not higher than the reaction pressure of the previous reactor.
4. The process according to claim 3, wherein

   The reaction temperature of the latter reactor is 5-60°C lower than that of the former reactor;

   And/or, the reaction pressure of the subsequent reactor is 0.5-4 MPa lower than the reaction pressure of the previous reactor.
5. The process according to claim 4, wherein

   The reaction temperature of the latter reactor is 10-50°C lower than that of the former reactor;

   And/or, the reaction pressure of the subsequent reactor is 1-2 MPa lower than the reaction pressure of the previous reactor.
6. The process according to claim 1, wherein

   The residence time of each stage of the reactor is independently 1-40 min.
7. The process according to claim 6, wherein

   The residence time of the first-stage reactor shall not be less than 8 minutes.
8. The process according to claim 1, wherein

   The molar ratio of dicyclopentadiene to ethylene is 1-20:1.
9. The process according to claim 1, wherein

   The pre-dissolution conditions include: temperature of 20-80° C. and pressure of 2-8 MPa.
10. The process according to claim 1, wherein

    The solubility of ethylene pre-dissolved in the inert solvent is lower than the solubility of ethylene in the reaction solution during the reaction.