Production process of norbornene

Abstract

The invention provides a production process of norbornene, and belongs to the technical field of norbornene synthesizing.The production process comprises the steps that a dicyclopentadiene solution and ethylene are fed into a first radial tubular reactor to react, the reaction temperature is 200-280 DEG C, the reaction pressure is 4-10 MPa, the reaction time is 1-2 h, and the reaction time is 1-2 h; the retention time of the dicyclopentadiene solution and the ethylene is 0.1-2 hours; the materials are fed into a second radial tubular reactor for a reaction, the reaction temperature is 160-260 DEG C, the reaction pressure is 4-10 MPa, and the retention time is 0.1-1 h; carrying out gas-liquid separation and rectification separation to obtain norbornene; and the first radial tubular reactor and the second radial tubular reactor are filled with inert fillers. According to the invention, mixing and mass transfer are enhanced, the process flow time is shortened, the process severity is reduced, the reaction conditions are milder, and the operation cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of norbornene synthesis technology, and specifically to a production process for norbornene. Background Technology

[0002] Norbornene, abbreviated as NB, has the chemical name bicyclo[2.2.1]-2-heptene and the molecular formula C7H10. It is a white, transparent crystal at room temperature, easily sublimates, and is highly flammable.

[0003] Industrially, norbornene is synthesized from ethylene and cyclopentadiene (CPD) via the Diels-Alder reaction. CPD primarily originates from the thermal decomposition of dicyclopentadiene (DCPD), a byproduct of the C5 fraction produced during naphtha cracking for ethylene production. DCPD is abundant, inexpensive, and facilitates the comprehensive utilization of the C5 fraction. Norbornene is mainly used in the synthesis of cyclic olefin copolymers (COC) and cyclic olefin polymers (COP), with a small amount used in the preparation of high-energy liquid fuels.

[0004] The efficient synthesis of norbornene highly depends on the uniform mixing and mass and heat transfer between raw materials to ensure complete reaction. Existing norbornene synthesis technologies have incorporated extensive design considerations for mixing and enhanced mass and heat transfer, but they still suffer from drawbacks such as numerous side reactions and poor selectivity of the main reaction. Therefore, for the synthesis of norbornene, designing the reactor to cleverly reduce side reactions and improve the selectivity of the main reaction is crucial.

[0005] Chinese patent application CN1284052A discloses a method and reactor for producing norbornene. It includes a reactant injection device. Liquid DCPD or a liquid DCPD-CPD mixture is substantially completely dispersed in supercritical ethylene under reaction conditions. Two coaxial tubes are used as injection devices to deliver the reactants through the bottom of the reactor. The two coaxial tubes extend axially beyond a portion of the reactor height. The DCPD or DCPD-CPD mixture originates from the central tube, and the ethylene originates from the annular space between the two coaxial tubes. The top of the system forms a strongly mixed zone for the reactants, while the bottom of the reactor forms a turbulent zone for the produced crude norbornene. The produced crude norbornene is discharged through the bottom of the reactor. This technology generally has limited enhancement effects on mass and heat transfer and requires dispersion of ethylene in a supercritical state.

[0006] Chinese patent application CN102249839A proposes a method for preparing norbornene in a loop reactor. First, dicyclopentadiene is preheated and decomposed in a heat exchanger to partially or completely decompose it into cyclopentadiene. Then, it is fed into the loop reactor and ethylene is introduced to react and obtain norbornene. The reaction temperature is 180-300℃, the outlet pressure is 5-30MPa, the molar ratio of ethylene to dicyclopentadiene is 1-20:1, and the recycle ratio is 100-300:1. This method has relatively harsh reaction conditions, and the dicyclopentadiene needs to be preheated and decomposed first, resulting in a long reaction process. This increases both operating costs and the safety risks of the reaction process.

[0007] Chinese patent application CN105585397A proposes a method for synthesizing vinyl norbornene using a multi-side-feed tubular reactor. This method divides the multi-side-feed tubular reactor into multiple reaction sections, with a feed inlet at the front of each section. The front of the first reaction section is the main feed inlet, while the others are side-feed inlets. This method is beneficial for the synthesis of norbornene. However, due to the large number of feed inlets and the static mixer between each feed inlet, problems such as long reaction process and high operating cost still exist.

[0008] Chinese patent application CN105481625A discloses a method for preparing norbornene from DCPD and ethylene. It employs p-tert-butylcatechol as a polymerization inhibitor and methyl isobutyl ketone (MIBK) as a solvent, using a two-reactor tandem process to synthesize norbornene. The proposed method uses a reaction pressure of 7-11 MPa, an ethylene to dicyclopentadiene molar ratio of 10-50:1, and a wide residence time distribution of the reactants, leading to polymer accumulation within the reactor as the reaction cycle extends.

[0009] Chinese patent application CN103664470A discloses a method for preparing norbornene, employing a process of first using a batch reactor and then a tubular reactor. In this method, DCPD, ethylene, and a solvent are mixed in a batch reactor, where DCPD partially decomposes into CPD. The mixture is then fed into the batch reactor for further reaction, and finally separated and purified to obtain norbornene with high yield and purity. While this patent application utilizes the advantages of both batch and tubular reactors to some extent, it fails to effectively utilize the reaction function of the batch reactor, merely using it as a decomposition device for DCPD. Furthermore, it has deficiencies and shortcomings in enhancing the uniform mixing of ethylene and CPD and in improving mass and heat transfer.

[0010] In summary, providing a novel production process for norbornene is one of the problems that urgently needs to be solved in this field. Summary of the Invention

[0011] The purpose of this invention is to provide a production process for norbornene, in order to solve the problems in norbornene synthesis technology such as poor enhanced mixing, poor enhanced mass and heat transfer, long process flow, high operating cost, and easy generation of polymers leading to low selectivity and yield of norbornene products.

[0012] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0013] This invention provides a process for producing norbornene, comprising the following steps:

[0014] S1, Dicyclopentadiene solution and ethylene are fed into the first radial tubular reactor for reaction at a temperature of 200-280℃ and a pressure of 4-10MPa. The residence time of the dicyclopentadiene solution and ethylene is 0.1-2h.

[0015] S2, the material is fed into the second radial tubular reactor for reaction, the reaction temperature is 160-260℃, the reaction pressure is 4-10MPa, and the residence time is 0.1-1h;

[0016] S3, the material is subjected to gas-liquid separation and distillation to obtain norbornene;

[0017] Both the first and second radial tubular reactors are filled with inert packing.

[0018] In the production process of norbornene described above, the height-to-diameter ratio of the first and second radial tubular reactors is 5-20:1.

[0019] The production process of norbornene as described above, wherein the reaction temperature in S1 is 200-260℃, the reaction pressure is 4-8MPa, and the residence time is 0.2-1.8h.

[0020] In the production process of norbornene described above, the reaction temperature in step S2 is 160-230℃, the reaction pressure is 4-8MPa, and the residence time is 0.3-1.5h.

[0021] The production process of norbornene as described above, wherein the inert packing includes one or more of Raschig ring packing, inert ceramic balls, stepped ring packing, corrugated packing, and rectangular saddle packing.

[0022] In the production process of norbornene described above, the mass fraction of dicyclopentadiene in the dicyclopentadiene solution is 10-80%, and the remainder is an inert solvent.

[0023] In the production process of norbornene as described above, the inert solvent includes one or more of the following: alkane inert solvents, fluoride solvents, ester inert solvents, carbonyl solvents, and chloride solvents.

[0024] In the production process of norbornene described above, the mass ratio of the dicyclopentadiene solution to ethylene is 5-20:1.

[0025] The production process of norbornene as described above, wherein the distillation separation conditions include: a reflux ratio of 1-10, a column top temperature of 0-40°C, and a column pressure of atmospheric pressure.

[0026] The production process of norbornene as described above further includes: premixing the dicyclopentadiene solution and ethylene before feeding them into the first radial tubular reactor.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] This invention provides a production process for norbornene. By employing two radial tubular reactors and filling them with inert packing material, the mixing and mass transfer are enhanced, the process time is shortened, the norbornene yield is increased, and the formation of polymers is reduced. By flexibly setting the process conditions of the two reactors, the reaction temperature, reaction pressure, and residence time are controlled, thereby reducing the severity of the process, making the reaction conditions more moderate, and lowering operating costs. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 This is a flowchart of the production process of norbornene according to the present invention;

[0031] Figure 2 This is a schematic diagram of the first and second radial tubular reactors of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Ethylene storage tank, 2-Dicyclopentadiene solution storage tank, 3-Premixing tank, 4-First radial tubular reactor, 5-Second radial tubular reactor, 6-High-precision tank, 7-Distillation column. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] On the one hand, the present invention provides a production process for norbornene, such as Figure 1 As shown, it includes the following steps:

[0036] S1, the dicyclopentadiene solution and ethylene are fed into the first radial tubular reactor 4 for reaction at a temperature of 200-280℃ and a pressure of 4-10MPa. The residence time of the dicyclopentadiene solution and ethylene is 0.1-2h.

[0037] S2, the material is fed into the second radial tubular reactor 5 for reaction, the reaction temperature is 160-260℃, the reaction pressure is 4-10MPa, and the residence time is 0.1-1h;

[0038] S3, the material is subjected to gas-liquid separation and distillation to obtain norbornene;

[0039] Both the first and second radial tubular reactors are filled with inert packing.

[0040] Figure 2 This is a schematic diagram of the first and second radial tubular reactors of the present invention.

[0041] This invention adjusts the residence time in the reactor by using first and second radial tubular reactors of different sizes. In conjunction with corresponding process conditions, the first radial tubular reactor can improve the conversion rate, while the second radial tubular reactor can bring the reaction to equilibrium and shorten the process time.

[0042] Inert packing is used in radial tubular reactors to enhance mixing and mass transfer, shorten process time, increase norbornene yield, and reduce polymer formation. By flexibly setting the process conditions of the two reactors, the reaction temperature, reaction pressure, and residence time can be controlled, thereby reducing the severity of the process, making the reaction conditions milder, and lowering operating costs.

[0043] In one specific embodiment, the height-to-diameter ratio of both the first and second radial tubular reactors is 5-20:1.

[0044] Currently, the synthesis of norbornene is mostly carried out using tubular or batch reactors. Typically, the process flow employs multiple reactors in series or a combination of batch and tubular reactors. After norbornene is synthesized in the reactors, the product is separated and purified by methods such as distillation. However, the homogeneous mixing and mass and heat transfer between the raw materials in existing technologies are not ideal, thus affecting the synthesis efficiency of norbornene. Using two reactors in combination achieves the overall effect of enhanced homogeneous mixing and mass and heat transfer, thereby improving the overall yield of norbornene synthesis.

[0045] In one specific embodiment, the reaction temperature in S1 is 200-260℃, the reaction pressure is 4-8MPa, and the residence time is 0.2-1.8h.

[0046] In one specific embodiment, the reaction temperature in S2 is 160-230℃, the reaction pressure is 4-8MPa, and the residence time is 0.3-1.5h.

[0047] In one specific embodiment, the inert packing is one or more of Raschig ring packing, inert ceramic balls, stepped ring packing, corrugated packing, and rectangular saddle packing.

[0048] The use of inert packing effectively enhances the uniform mixing and mass and heat transfer of the reactants in the reactor bed, thereby directly improving the yield of norbornene.

[0049] In one specific embodiment, the dicyclopentadiene solution contains 10-80% by mass of dicyclopentadiene, with the remainder being an inert solvent.

[0050] In one specific embodiment, the dicyclopentadiene solution contains 20-70% dicyclopentadiene by mass.

[0051] In one specific embodiment, the dicyclopentadiene solution contains a dicyclopentadiene mass fraction of 25-65%.

[0052] In one specific embodiment, the inert solvent is one or more of the following: alkane inert solvents, fluoride solvents, ester inert solvents, carbonyl solvents, and chloride solvents.

[0053] In one specific embodiment, the inert solvent is one or more hydrocarbon solvents.

[0054] In one specific embodiment, the hydrocarbon solvent is one or more of benzene, toluene, xylene, trimethylbenzene, and ethylbenzene.

[0055] In one specific embodiment, the mass ratio of the dicyclopentadiene solution to ethylene is 5-20:1.

[0056] In one specific embodiment, the conditions for distillation separation include: a reflux ratio of 1-10, a column top temperature of 0-40°C, and a column pressure of atmospheric pressure.

[0057] In one specific embodiment, the conditions for distillation separation include: a reflux ratio of 4-8 and a column top temperature of 10-40°C.

[0058] In one specific embodiment, a distillation column 6 is selected for distillation separation, and the number of trays in the distillation column 6 is 10-30.

[0059] In one specific embodiment, the number of trays in the distillation column 6 is 15-25.

[0060] In one specific implementation, the ethylene separated by distillation is returned to the ethylene storage tank 1, which improves the economics of the production process.

[0061] In one specific embodiment, the gas obtained from gas-liquid separation is recycled to the dicyclopentadiene solution storage tank 2 for reuse.

[0062] In one specific embodiment, the process further includes premixing the dicyclopentadiene solution and ethylene before feeding them into the first radial tubular reactor 4.

[0063] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0064] Example 1

[0065] This embodiment provides a production process for norbornene, including the following steps:

[0066] 50 wt% of dicyclopentadiene / toluene solvent and ethylene are premixed in a premixing tank 3, wherein the mass ratio of dicyclopentadiene / toluene solvent to ethylene is 10:1. The premixed material is then fed into a first radial tubular reactor 4 with a height-to-diameter ratio of 10:1 for reaction. The reaction temperature in the reactor is 260℃, the pressure is 5.8 MPa, and the residence time is 2 h. The first radial tubular reactor 4 is filled with Raschig ring packing with a porosity of 25%.

[0067] The product obtained from the reaction preparation was fed into a second radial tubular reactor 5 with a height-to-diameter ratio of 6:1 for reaction. The reaction temperature was 200℃, the pressure was 5.8MPa, and the residence time was 30min. The second radial tubular reactor 5 was filled with inert ceramic balls with a porosity of 37%.

[0068] The product obtained from the reaction is separated into gas and liquid in a high-precision tank 6. The gas is refluxed to the dicyclopentadiene solution storage tank 2, and the liquid enters a distillation unit with 15 trays. The distillation separation conditions include: reflux ratio of 5, top temperature of 30°C, and atmospheric pressure. The separated ethylene is refluxed to the ethylene storage tank, and norbornene is obtained by distillation.

[0069] Example 2

[0070] This embodiment provides a production process for norbornene, including the following steps:

[0071] 65 wt% of dicyclopentadiene / xylene and ethylene are premixed in a premixing tank 3, wherein the mass ratio of dicyclopentadiene / xylene solvent to ethylene is 7:1. The premixed material is then fed into a first radial tubular reactor 4 with a height-to-diameter ratio of 8:1 for reaction. The reaction temperature in the reactor is 250°C, the pressure is 6 MPa, and the residence time is 0.4 h. The first radial tubular reactor 4 is filled with inert ceramic balls with a porosity of 37%.

[0072] The product obtained from the reaction preparation was fed into a second radial tubular reactor 5 with a height-to-diameter ratio of 5:1 for reaction. The reaction temperature was 220℃, the pressure was 6MPa, and the residence time was 0.1h. The second radial tubular reactor 5 was filled with stepped ring packing with a porosity of 66%.

[0073] The product obtained from the reaction is separated into gas and liquid in a high-precision tank 6. The gas is refluxed to the dicyclopentadiene solution storage tank 2, and the liquid enters a distillation unit with 17 trays. The distillation separation conditions include: reflux ratio of 4, top temperature of 38°C, and atmospheric pressure. The separated ethylene is refluxed to the ethylene storage tank 1, and norbornene is obtained by distillation.

[0074] Example 3

[0075] This embodiment provides a production process for norbornene, including the following steps:

[0076] 45 wt% of dicyclopentadiene / xylene and ethylene are premixed in a premixing tank 3, wherein the mass ratio of dicyclopentadiene / xylene to ethylene is 5:1. The premixed material is then fed into a first radial tubular reactor 4 with a height-to-diameter ratio of 7:1 for reaction. The reaction temperature in the reactor is 240℃, the pressure is 5.3 MPa, and the residence time is 0.6 h. The first radial tubular reactor 4 is filled with corrugated packing with a porosity of 55%.

[0077] The product obtained from the reaction preparation was fed into a second radial tubular reactor 5 with a height-to-diameter ratio of 5:1 for reaction. The reaction temperature was 180℃, the pressure was 5.3MPa, and the residence time was 0.15h. The second radial tubular reactor 5 was filled with inert ceramic balls with a porosity of 53%.

[0078] The product obtained from the reaction is separated into gas and liquid in a high-precision tank 6. The gas is refluxed to the dicyclopentadiene solution storage tank 2, and the liquid enters a distillation unit with 15 trays. The distillation separation conditions include: reflux ratio of 7, top temperature of 30°C, and atmospheric pressure. The separated ethylene is refluxed to the ethylene storage tank 1, and norbornene is obtained by distillation.

[0079] Example 4

[0080] This embodiment provides a production process for norbornene, including the following steps:

[0081] 30 wt% of dicyclopentadiene / ethylbenzene solvent and ethylene are premixed in a premixing tank 3, wherein the mass ratio of dicyclopentadiene / ethylbenzene solvent to ethylene is 5:1. The premixed material is then fed into a first radial tubular reactor 4 with a height-to-diameter ratio of 8:1 for reaction. The reaction temperature in the reactor is 250℃, the pressure is 5.2 MPa, and the residence time is 0.3 h. The first radial tubular reactor 4 is filled with rectangular saddle packing with a porosity of 35%.

[0082] The product obtained from the reaction preparation was fed into a second radial tubular reactor 5 with a height-to-diameter ratio of 6:1 for reaction. The reaction temperature was 220℃, the pressure was 5.2MPa, and the residence time was 0.75h. The second radial tubular reactor 5 was filled with inert ceramic balls with a porosity of 40%.

[0083] The product obtained from the reaction is separated into gas and liquid in a high-precision tank 6. The gas is refluxed to the dicyclopentadiene solution storage tank 2, and the liquid enters a distillation unit with 15 trays. The distillation separation conditions include: reflux ratio of 8, top temperature of 26°C, and atmospheric pressure. The separated ethylene is refluxed to the ethylene storage tank 1, and norbornene is obtained by distillation.

[0084] Comparative Example 1

[0085] The reactor used in this comparative example is an axial tubular reactor with a packing layer inside. The packing layer is filled with a mixture of 5mm×5mm θ rings of copper-zinc-aluminum catalyst and 6mm×6mm θ rings of metal wire mesh, and is filled in a uniform mixing manner. The porosity of the packing layer is 70%.

[0086] This comparative example provides a method for norbornene, comprising the following steps:

[0087] A solution of dicyclopentadiene (65 wt% dicyclopentadiene, toluene as solvent) and ethylene were fed from top to bottom into an axial tubular reactor, allowing the dicyclopentadiene and ethylene to undergo a superposition reaction under plug flow conditions. The reaction temperature was 260 °C, the pressure was 5.7 MPa, and the mass hourly space velocity (HSV) of the dicyclopentadiene solution was 1 h⁻¹. -1 The mass ratio of dicyclopentadiene solution to ethylene is 5:1. The resulting norbornene mixture is continuously discharged and separated by distillation to obtain norbornene.

[0088] Test case

[0089] The products of Examples 1-4 and Comparative Examples 1-5 were analyzed by gas chromatography.

[0090] The results are as follows:

[0091] The conversion rate of dicyclopentadiene in Example 1 was 98.4%, the selectivity of norbornene was 93.5%, and the selectivity of tricyclic and higher polymers was 2.1%.

[0092] The conversion rate of dicyclopentadiene in Example 2 was 95.4%, the selectivity of norbornene was 92.7%, and the selectivity of tricyclic and higher polymers was 2.3%.

[0093] The conversion rate of dicyclopentadiene in Example 3 was 92.4%, the selectivity of norbornene was 91.3%, and the selectivity of tricyclic and higher polymers was 2.8%.

[0094] The conversion rate of dicyclopentadiene in Example 4 was 99.4%, the selectivity of norbornene was 96.7%, and the selectivity of tricyclic and higher polymers was 3.2%.

[0095] The conversion rate of dicyclopentadiene in Comparative Example 1 was 82.5%, the selectivity of norbornene was 84.8%, and the selectivity of tricyclic and higher polymers was 9.3%.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A production process for norbornene, characterized in that, Includes the following steps: S1, Dicyclopentadiene solution and ethylene are fed into the first radial tubular reactor for reaction at a temperature of 200-280℃ and a pressure of 4-10MPa. The residence time of the dicyclopentadiene solution and ethylene is 0.1-2h. S2, the material is fed into the second radial tubular reactor for reaction, the reaction temperature is 160-260℃, the reaction pressure is 4-10MPa, and the residence time is 0.1-1h; S3, the material is subjected to gas-liquid separation and distillation to obtain norbornene; Both the first radial tubular reactor and the second radial tubular reactor are filled with inert packing.

2. The production process according to claim 1, characterized in that, The height-to-diameter ratio of both the first radial tubular reactor and the second radial tubular reactor is (5-20):

1.

3. The production process according to claim 1, characterized in that, The reaction temperature in S1 is 200-260℃, the reaction pressure is 4-8MPa, and the residence time is 0.2-1.8h.

4. The production process according to claim 1, characterized in that, The reaction temperature in S2 is 160-230℃, the reaction pressure is 4-8MPa, and the residence time is 0.3-1.5h.

5. The production process according to claim 1, characterized in that, The inert packing includes one or more of Raschig ring packing, inert ceramic balls, stepped ring packing, corrugated packing, and rectangular saddle packing.

6. The production process according to any one of claims 2-5, characterized in that, In the dicyclopentadiene solution, the mass fraction of dicyclopentadiene is 10-80%, and the remainder is an inert solvent.

7. The production process according to claim 6, characterized in that, The inert solvent includes one or more of the following: alkane inert solvents, fluoride solvents, ester inert solvents, carbonyl solvents, and chloride solvents.

8. The production process according to claim 7, characterized in that, The mass ratio of the dicyclopentadiene solution to ethylene is (5-20):

1.

9. The production process according to claim 1, characterized in that, The conditions for the distillation separation include: a reflux ratio of 1-10, a top temperature of 0-40°C, and a pressure of atmospheric pressure.

10. The production process according to claim 1, characterized in that, The process further includes premixing the dicyclopentadiene solution and ethylene before feeding them into the first radial tubular reactor.

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