Preparation method of 2, 6-dimethylnaphthalene
By conducting aromatization reaction in the presence of an acid catalyst and simplifying the preparation steps with olefin-containing raw materials, the problems of complex and costly preparation process in the prior art were solved, efficient and economical production was achieved, and the development of PEN polyester materials was promoted.
Patent Information
- Application Number
- CN202311701419.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2025-06-13
AI Technical Summary
In the prior art, the preparation process of 2,6-dimethylnaphthalene is complex and costly, limiting its large-scale application in PEN polyester materials.
The aromatization reaction is carried out in the presence of an acid catalyst, and a olefin-containing raw material, such as MTP gasoline, is used to obtain 2,6-dimethylnaphthalene through one-step reaction, and a high-purity product is obtained by separation and purification.
The preparation steps are simplified, production costs are reduced, and 2,6-dimethylnaphthalene is achieved efficient and economical production, which promotes the development of PEN polyester materials.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of light hydrocarbon aromatization, and particularly to a method for preparing 2,6-dimethylnaphthalene. Background Art
[0002] 2,6-Dimethylnaphthalene (2,6-DMN) is a key raw material for synthesizing naphthalene polymers. Its oxidation product, 2,6-naphthalenedicarboxylic acid, is polycondensed with ethylene glycol to obtain polyethylene naphthalate (PEN), which is a new type of high-performance polyester material. PEN has excellent heat resistance, chemical properties, mechanical properties, gas barrier properties, and mechanical properties, and has great application prospects in the fields of electronic components, aerospace, and food packaging. However, the limitation of the raw material 2,6-dialkylnaphthalene for PEN production has become a bottleneck for its application.
[0003] Currently, 2,6-dimethylnaphthalene can be obtained through chemical synthesis methods and direct extraction methods. The chemical synthesis method uses pure substances such as toluene or xylene as raw materials and obtains 2,6-dimethylnaphthalene through multiple steps of synthesis. This synthesis process is complex, the process flow is long, and the production cost is high. The direct extraction method uses petroleum coal tar and heavy aromatic hydrocarbons from refinery by-products as raw materials, and obtains 2,6-dialkylnaphthalene through separation means such as crystallization method, adsorption-desorption method, complexation crystallization method, pressure crystallization method, and emulsification crystallization method. However, the content of 2,6-dimethylnaphthalene in raw materials such as coal tar and heavy aromatic hydrocarbons in refinery products is low, the separation cost is very high, and the process route is relatively complex, which seriously restricts the large-scale entry of PEN into the market.
[0004] Therefore, developing a production method for 2,6-dialkylnaphthalene with a simple process and reducing its production cost is of great significance for promoting the development of PEN polyester materials in China. Summary of the Invention
[0005] The purpose of the present invention is to overcome the problems of cumbersome preparation process and high cost in the prior art, and provide a method for preparing 2,6-dimethylnaphthalene, which simplifies the preparation steps and reduces the production cost.
[0006] To achieve the above purpose, the present invention provides a method for preparing 2,6-dimethylnaphthalene, including:
[0007] In the presence of an acidic catalyst, subjecting a raw material containing olefins to an aromatization reaction to obtain a first product; wherein, the acidic catalyst is zeolite or zeolite containing a metal active component; in the raw material containing olefins, the mass percentage content of olefins is 5-65%, and the olefins are C 2 -C 7 olefins;
[0008] Separating and purifying the first product to obtain a 2,6-dimethylnaphthalene product.
[0009] Through the above technical solutions, the beneficial technical effects achieved by the present invention are as follows:
[0010] The method proposed by the present invention has a simple reaction process. In the presence of an acidic catalyst of zeolite or zeolite containing a metal active component, the 2,6-dimethylnaphthalene component can be obtained only through one-step reaction. The raw materials required by the present invention are cheap, reducing the production cost. Detailed Description of the Invention
[0011] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.
[0012] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.
[0013] Unless otherwise specified, all pressures mentioned in this specification refer to gauge pressure.
[0014] In the context of this specification, the reaction temperature refers to the hot spot temperature of the catalyst bed, and the hot spot temperature refers to the highest temperature in the catalyst bed. The present invention provides a method for preparing 2,6-dimethylnaphthalene, comprising the following steps:
[0015] (1) In the presence of an acidic catalyst, subject a raw material containing olefins to an aromatization reaction to obtain a first product; wherein, the acidic catalyst is zeolite or zeolite containing a metal active component; in the raw material containing olefins, the mass percentage content of olefins is 5-65%, and the olefins are C 2 -C 7 olefins;
[0016] (2) Separate and purify the first product to obtain 2,6-dimethylnaphthalene.
[0017] The method proposed by the present invention has a simple reaction process. In the presence of an acidic catalyst of zeolite or zeolite containing a metal active component, the 2,6-dimethylnaphthalene component can be obtained only through one-step reaction. The raw materials required by the present invention are cheap, reducing the production cost.
[0018] The present invention solves the problem that the current industrial production of 2,6-dimethylnaphthalene requires relatively expensive raw materials such as α-methylnaphthalene, o-xylene, dipentene, etc., and needs to undergo multiple reactions such as acylation and alkylation steps to obtain 2,6-dimethylnaphthalene. This method uses inexpensive raw materials, such as the by-product gasoline of the MTP process, which contains olefins as raw materials. The catalysts used are also common catalysts, and 2,6-dimethylnaphthalene can be obtained through only one-step reaction, which can greatly reduce its synthesis cost and simplify its synthesis steps.
[0019] In some embodiments, in the olefin-containing raw material, the mass percentage content of diolefin is 1.5-10%; the diolefin is a diolefin of C 2 -C 7 .
[0020] In some embodiments, the zeolite is ZSM-5, UZM-39, UZM-44 or MCM-22.
[0021] In some embodiments, the metal active component contains one or more of Ga, Pd, Sn, Pt, Zn, Ni, etc., preferably one or more of Ga, Zn, Pt, Ni, such as gallium nitrate, zinc nitrate, platinum nitrate, nickel nitrate; the zeolite containing the metal active component is preferably Ga / ZSM-5, Zn / ZSM-5, Pt / ZSM-5 or Ni 2 P / ZSM-5. The acidic catalyst is preferably Zn / ZSM-5.
[0022] In some preferred embodiments, in the zeolite containing the metal active component, the metal active component accounts for 1-5 wt% of the total amount of the acidic catalyst.
[0023] According to the present invention, the temperature of the aromatization reaction is 400-600 °C, the pressure is 0.01-3 MPa, and the weight hourly space velocity of the olefin-containing raw material is 0.1-5 h -1 ;
[0024] Preferably, the temperature of the aromatization reaction is 480-580, the pressure is 0.01-1 MPa, and the weight hourly space velocity of the olefin-containing raw material is 0.5-2 h -1 . Using the preferred aromatization reaction conditions is more conducive to improving the yield of 2,6-dimethylnaphthalene.
[0025] In some embodiments, the aromatization reaction is carried out under the protection of an inert gas; the inert gas is nitrogen.
[0026] In some preferred embodiments, the gas velocity of the inert gas is 10-100 sccm; preferably 15-50 sccm.
[0027] According to the present invention, the aromatization reaction is carried out in a liquid-solid phase reactor, for example, a fixed bed reactor, a fluidized bed reactor, a moving bed reactor or a trickle bed reactor; preferably, it is carried out in a fixed bed reactor.
[0028] The method for separating and purifying the first product obtained in step (1) of the present invention is not particularly limited, as long as the purpose of separating and purifying 2,6-dimethylnaphthalene can be achieved, including but not limited to: complexation separation method, rectification separation, crystallization separation, extraction separation, emulsification crystallization, etc., and preferably the complexation separation method is adopted.
[0029] In some embodiments, the separation and purification is the complexation separation method, and the complexing agent used in the complexation separation method is a mixture of m-nitrobenzoic acid and methanol, wherein the mass ratio of m-nitrobenzoic acid to methanol is 0.3-8:1, preferably 1-5:1; the mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene in the first product is 3-6:1, preferably 4-5:1.
[0030] Specifically, the steps of the complexation separation method are as follows: add a mixed solution of m-nitrobenzoic acid and methanol with a mass ratio of 0.3-8.0:1 to the first product obtained in step (1), then carry out a complexation reaction at 80-100 °C, the complexation reaction time is 10-50 minutes, and at the same time collect the methanol distilled out during the reaction process, cool the reaction product to crystallize the complex therein, and then separate the solid from the liquid. The mass ratio of m-nitrobenzoic acid contained in the mixed solution to 2,6-dimethylnaphthalene in the first product is 3-6:1.
[0031] In some preferred embodiments, the purity of the 2,6-dimethylnaphthalene product is greater than or equal to 98 wt%.
[0032] In some embodiments, the olefin-containing raw material is MTP gasoline, wherein the olefin content is 5-65 wt%, preferably 30-60 wt%, and the diolefin content is 1.5-10 wt%, preferably 5-9 wt%.
[0033] According to the present invention, after the reaction in step (1) is completed, the first product is subjected to chromatographic detection, and it is obtained that the content of 2,6-dimethylnaphthalene in the first product is 2-8 wt%.
[0034] In the present invention, MTP gasoline refers to the by-product gasoline of a methanol-to-propylene (MTP) unit, and the distillation range is 60-210 °C.
[0035] The inventors of the present invention found in the research that by using MTP gasoline as a raw material and carrying out an aromatization reaction in the presence of an acidic catalyst, 2,6-dimethylnaphthalene can be generated, and pure 2,6-dimethylnaphthalene can be obtained through separation and purification.
[0036] In some preferred embodiments, in the first product, the content of 2,6-dimethylnaphthalene is 2-8 wt%.
[0037] In some embodiments, after the step of separating and purifying the first product to obtain a 2,6-dimethylnaphthalene product, the following steps are further included:
[0038] The material after separation and purification is oxidized to obtain 2,6-naphthalenedicarboxylic acid, and then poly(ethylene naphthalate) can be obtained by polycondensation with ethylene glycol.
[0039] It can be seen from the above technical solutions that the reaction process of the method of the present invention is simple, the raw materials are cheap, and the production cost is reduced.
[0040] In order to further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.
[0041] Unless otherwise specified, the reagents involved in the embodiments of the present invention are all commercially available products and can be obtained through commercial channels.
[0042] In the following examples, MTP gasoline is a gasoline component produced by the methanol-to-propylene process, and the distillation range is 60-210 °C.
[0043] ZSM-5 is a commercially available product of Zeolyst with the model CBV3024E, the silica-alumina ratio is 30, and the specific surface area is 405 m 2 / g.
[0044] Example 1
[0045] (1) Using ZSM-5 molding agent as the catalyst, 2.0 g of the catalyst was loaded into the reaction tube in a fixed-bed reactor, the reaction temperature was controlled at 400 °C, nitrogen was used as the carrier gas, the gas velocity was controlled at 15 sccm, and MTP gasoline was used as the raw material for the aromatization reaction, and the space velocity was 1.0 h -1 ; after the reaction, the reaction solution was detected by gas chromatography, and the content of 2,6-dimethylnaphthalene was 3.5 wt%;
[0046] (2) Add a complexing agent to the reaction solution obtained in step (1). The complexing agent is a mixture of m-nitrobenzoic acid and methanol with a mass ratio of 3:1. The mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene contained in the reaction solution obtained in step (1) is 5:1. Conduct a complexation reaction at 90 °C for 30 minutes. Meanwhile, collect the methanol distilled during the reaction process. Cool the reaction product to crystallize the complex therein, and then separate the solid from the liquid to obtain 2,6-dimethylnaphthalene.
[0047] Detected by gas chromatography, the purity of 2,6-dimethylnaphthalene is 98.5 wt%.
[0048] Example 2
[0049] (1) Use Ga / ZSM-5 forming agent as the catalyst, with Ga accounting for 3 wt% of the total amount of Ga / ZSM-5. Load 2.0 g of the catalyst into the reaction tube in a fixed-bed reactor. The reaction temperature is 540 °C, use nitrogen as the carrier gas, control the gas velocity at 15 sccm, use MTP gasoline as the raw material, and conduct an aromatization reaction with a space velocity of 1.0 h -1 ; After the reaction is completed, conduct gas chromatography detection on the reaction solution. The content of 2,6-dimethylnaphthalene is 4.0 wt%;
[0050] (2) Add a complexing agent to the reaction solution obtained in step (1). The complexing agent is a mixture of m-nitrobenzoic acid and methanol with a mass ratio of 4:1. The mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene contained in the reaction solution obtained in step (1) is 4:1. Conduct a complexation reaction at 100 °C for 20 minutes. Meanwhile, collect the methanol distilled during the reaction process. Cool the reaction product to crystallize the complex therein, and then separate the solid from the liquid to obtain 2,6-dimethylnaphthalene.
[0051] Detected by gas chromatography, the purity of 2,6-dimethylnaphthalene is 99.0 wt%.
[0052] Example 3
[0053] (1) Use Zn / ZSM-5 forming agent as the catalyst, with Zn accounting for 5 wt% of the total amount of Zn / ZSM-5. Load 2.0 g of the catalyst into the reaction tube in a fixed-bed reactor. The reaction temperature is 450 °C, use nitrogen as the carrier gas, control the gas velocity at 10 sccm, use MTP gasoline as the raw material, and conduct an aromatization reaction with a space velocity of 2.0 h -1 ; After the reaction is completed, conduct gas chromatography detection on the reaction solution. The content of 2,6-dimethylnaphthalene is 2.8 wt%;
[0054] (2) Add a complexing agent to the reaction solution obtained in step (1). The complexing agent is a mixture of m-nitrobenzoic acid and methanol with a mass ratio of 5:1. The mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene contained in the reaction solution obtained in step (1) is 6:1. Carry out the complexation reaction at 90 °C for 50 minutes. At the same time, collect the methanol distilled out during the reaction. Cool the reaction product to crystallize the complex therein, and then separate the solid from the liquid to obtain 2,6-dimethylnaphthalene.
[0055] Detected by gas chromatography, the purity of 2,6-dimethylnaphthalene is 98.8 wt%.
[0056] Example 4
[0057] (1) Use Pt / ZSM-5 forming agent as the catalyst, with Pt accounting for 1 wt% of the total amount of Pt / ZSM-5. Load 2.0 g of the catalyst into the reaction tube in a fixed-bed reactor. The reaction temperature is 450 °C. Use nitrogen as the carrier gas, control the gas velocity at 10 sccm, and use MTP gasoline as the raw material to carry out the aromatization reaction with a space velocity of 1.5 h -1 ; After the reaction is completed, detect the reaction solution by gas chromatography. The content of 2,6-dimethylnaphthalene is 3.9 wt%;
[0058] (2) Add a complexing agent to the reaction solution obtained in step (1). The complexing agent is a mixture of m-nitrobenzoic acid and methanol with a mass ratio of 8:1. The mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene contained in the reaction solution obtained in step (1) is 3:1. Carry out the complexation reaction at 95 °C for 40 minutes. At the same time, collect the methanol distilled out during the reaction. Cool the reaction product to crystallize the complex therein, and then separate the solid from the liquid to obtain 2,6-dimethylnaphthalene.
[0059] Detected by gas chromatography, the purity of 2,6-dimethylnaphthalene is 99.1 wt%.
[0060] Comparative Example 1
[0061] Prepare 2,6-dimethylnaphthalene according to the method of Example 1, except that commercially available gasoline is used as the raw material
[0062] After the reaction is completed, detect the reaction solution by gas chromatography. The content of 2,6-dimethylnaphthalene is 0.02 wt%.
[0063] Comparative Example 2
[0064] Prepare 2,6-dimethylnaphthalene according to the method of Example 1, except that the catalyst SAPO-34 is used
[0065] After the reaction was completed, the reaction solution was detected by gas chromatography, and the content of 2,6-dimethylnaphthalene was 0 wt%.
[0066] As can be seen from the above Examples 1-4, using MTP gasoline as the raw material to prepare 2,6-dimethylnaphthalene, the reaction process of this method is simple, the raw materials are cheap, and the production cost can be greatly reduced.
[0067] As can be seen from the comparison between Comparative Example 1 and the Examples, using MTP gasoline is the key to preparing 2,6-dimethylnaphthalene, and the olefins and diolefins in its components are easily converted into 2,6-dimethylnaphthalene through reaction.
[0068] As can be seen from the comparison between Comparative Example 2 and the Examples, the ten-membered ring structure of ZSM-5 molecular sieve is the key to the formation of 2,6-dimethylnaphthalene.
[0069] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.
Claims
1. A preparation method of 2,6-dimethylnaphthalene, characterized in that, comprising: In the presence of an acidic catalyst, an olefin-containing feedstock is subjected to an aromatization reaction to obtain a first product; wherein, the acidic catalyst is zeolite or zeolite containing a metal active component; in the olefin-containing feedstock, the mass percentage content of olefin is 5-65%, and the olefin is C 2 -C 7 olefin; Separating and purifying the first product to obtain a 2,6-dimethylnaphthalene product.
2. The preparation method according to claim 1, wherein, In the olefin-containing feedstock, the mass percentage of diolefin is 1.5-10 wt%; the diolefin is a diolefin of C 2 -C 7 .
3. The preparation method according to claim 1 or 2, wherein, The zeolite is ZSM-5, UZM-39, UZM-44 or MCM-22.
4. The preparation method according to any one of claims 1-3, wherein, The metal active component contains one or more of Ga, Pd, Sn, Pt, Zn, and Ni; the zeolite containing the metal active component is preferably Ga / ZSM-5, Zn / ZSM-5, Pt / ZSM-5, or Ni 2 P / ZSM-5; Preferably, the metal active component accounts for 1-5 wt% of the total amount of the acidic catalyst.
5. The preparation method according to any one of claims 1-4, wherein, The temperature of the aromatization reaction is 400-600°C, the pressure is 0.01-3 MPa, and the weight hourly space velocity of the olefin-containing feedstock is 0.1-5 h -1 ; Preferably, the temperature of the aromatization reaction is 480 - 580 °C, the pressure is 0.01 - 1 MPa, and the weight hourly space velocity of the olefin-containing feedstock is 0.5 - 2 h -1 ; Preferably, the aromatization reaction is carried out in a fixed bed reactor.
6. The preparation method according to any one of claims 1-5, wherein, The aromatization reaction is carried out under the protection of an inert gas; the inert gas is nitrogen; Preferably, the gas velocity of the inert gas is 10-100 sccm; preferably 15-50 sccm.
7. The preparation method according to any one of claims 1-6, wherein, The separation and purification is a complexation separation method, and the complexing agent used in the complexation separation method is a mixture of m-nitrobenzoic acid and methanol, wherein the mass ratio of m-nitrobenzoic acid to methanol is 0.3-8:1, and the mass ratio of m-nitrobenzoic acid to 2,6-dimethylnaphthalene in the first product is 3-6:
1.
8. The preparation method according to claim 7, wherein, The purity of the 2,6-dimethylnaphthalene product is greater than or equal to 98 wt%.
9. The preparation method according to any one of claims 1-8, wherein, The olefin-containing raw material is MTP gasoline, wherein the olefin content is 5-65 wt%, preferably 30-60 wt%, and the diolefin content is 1.5-10 wt%, preferably 5-9 wt%; Preferably, in the first product, the content of 2,6-dimethylnaphthalene is 2-8 wt%.
10. The preparation method according to claim 9, wherein, After the step of separating and purifying the first product to obtain a 2,6-dimethylnaphthalene product, it further includes: Oxidizing the separated and purified material to obtain 2,6-naphthalenedicarboxylic acid, and then polycondensing with ethylene glycol to obtain polyethylene naphthalate.