CN112645811A - Method for preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene - Google Patents
Method for preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene Download PDFInfo
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- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
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Abstract
The invention relates to a method for preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene, which mainly solves the problems of low yield of 2,6-NDA and low purity of 2,6-NDA when preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene, and comprises the following steps: (1) adding a catalyst, a solvent and 2, 6-naphthalenedicarboxylic acid into a reaction kettle, controlling the temperature in the reaction kettle to be 160-220 ℃ and the reaction pressure to be 2-3 MPa; (2) adding 2, 6-diisopropyl naphthalene into the reaction kettle, and introducing gas containing free oxygen to react; (3) after the feeding of the 2, 6-diisopropyl naphthalene is finished, continuously reacting for 0.5 to 2 hours to obtain a product 2,6-naphthalene dicarboxylic acid mixture; the technical scheme that the catalyst in the step (1) contains Co, Mn, Br and K better solves the problem.
Description
Technical Field
The invention relates to a method for preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene, in particular to a method for preparing 2,6-naphthalene dicarboxylic acid by air oxidizing 2, 6-diisopropyl naphthalene.
Background
2,6-naphthalene dicarboxylic acid (2,6-NDA) and derivatives thereof are important monomers for preparing various polyesters, polyurethane materials, Liquid Crystal Polymers (LCP) and the like, and particularly polyethylene naphthalate (PEN) prepared by polycondensation of 2,6-NDA and ethylene glycol has wide application prospects in films, packaging containers (especially beer bottles) and industrial fibers. Due to the high degree of symmetry in the 2,6-NDA structure. The PEN has the characteristics of a straight-chain polymer, and is a high-performance material with good rigidity, high strength and excellent hot workability. Compared with polyethylene terephthalate (PET), PEN has better heat resistance, barrier property, mechanical property, chemical resistance, ultraviolet resistance and the like. Currently, the industry mainly synthesizes 2,6-NDA by air liquid phase oxidation of dialkyl naphthalene under Co-Mn-Br catalyst, for example, U.S. Pat. No. 5, 5183933 (titled: Process for preparation 2,6-naphthalene-dicarboxylic acid) uses 2, 6-dimethylnaphthalene (2,6-DMN) to prepare 2,6-NDA with 93% yield. In various liquid-phase oxidation methods of 2, 6-dialkylnaphthalene, because the physical properties of 2, 6-dimethylnaphthalene are similar to the physical and chemical properties of 2, 7-dimethylnaphthalene, separation is difficult and operation cost is high; and 2, 6-diisopropyl naphthalene (2,6-DIPN) is easy to separate and purify from raw materials (isomer mixture), and the operation cost is lower. Therefore, the process route for preparing 2,6-NDA by the 2,6-DIPN oxidation method has more development prospect in view of industrial production and economic cost. In order to improve the yield of the oxidized product 2,6-NDA and to suppress the occurrence of side reactions, many researchers have conducted studies. It is found that in the oxidation reaction of 2, 6-diisopropyl naphthalene, the concentration of raw materials in a reactor is not suitable to be too high, otherwise, the reaction is too fast in the initial stage, so that the side reaction is accelerated, the yield of 2,6-NDA is reduced, and the trimellitic acid as a byproduct is increased. The continuous feeding of 2, 6-diisopropyl naphthalene or the adding of a small amount of 2, 6-diisopropyl naphthalene can be adopted to control the raw materials in the reactor to be kept in a low concentration state. For example, in the patent US4709088 (titled: Process for preparing 2,6-naphthalene-dicarboxylic acid), a semi-continuous mode is adopted for feeding, 2,6-DIPN as a raw material is continuously added into a mixed solution of a catalyst and a solvent for reaction at a certain speed, and after the feeding is finished, deep oxidation is carried out for 2 hours, so that the yield of 2,6-DNA is 91.7 mol%, but the dosage of the catalyst is very large. However, the use of a large amount of expensive heavy metal catalyst (especially Co) increases the product cost and is not favorable for industrial production. In addition, 2,6-DNA crystals obtained with a high catalyst content are difficult to filter and separate, the particles after drying are very small, dust is easily generated, and transportation is difficult (pyronin et al. 2, 6-naphthalenedicarboxylic acid synthesis and purification technology advances [ J ]. petrochemical technology and applications 2002, 20 (6): 410-). 416).
Disclosure of Invention
The invention mainly solves the problems of low yield of 2,6-NDA and low purity of 2,6-NDA in the process of preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene, and provides a method for preparing 2,6-naphthalene dicarboxylic acid by oxidizing 2, 6-diisopropyl naphthalene, which has the advantages of high yield of 2,6-NDA and high purity of 2, 6-NDA.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the process of oxidizing 2, 6-diisopropyl naphthalene to prepare 2,6-naphthalene dicarboxylic acid includes the following steps:
(1) adding a catalyst, a solvent and 2, 6-naphthalenedicarboxylic acid into a reaction kettle, controlling the temperature in the reaction kettle to be 160-220 ℃ and the reaction pressure to be 2-3 MPa;
(2) adding 2, 6-diisopropyl naphthalene into the reaction kettle, and introducing gas containing free oxygen to react;
(3) after the feeding of the 2, 6-diisopropyl naphthalene is finished, continuously reacting for 0.5 to 2 hours to obtain a product 2,6-naphthalene dicarboxylic acid mixture;
the catalyst in the step (1) contains Co, Mn, Br and K.
The invention adds 2,6-naphthalene dicarboxylic acid into the initial reaction mixture, thus improving the yield and purity of the 2,6-naphthalene dicarboxylic acid.
In the above technical solution, the gas containing free oxygen is preferably air.
In the above technical solution, the solvent in step (1) is preferably independently selected from acetic acid and/or propionic acid, and acetic acid is more preferably used from the industrial viewpoint and the cost viewpoint.
In the above technical solution, in the catalyst in the step (1), the molar ratio of Mn to Co is preferably 0.5 to 2, for example, but not limited to, 0.52, 0.55, 1, 1.12, 1.52, 1.82, and 1.98.
In the above technical solution, in the catalyst in the step (1), the molar ratio of Br to Co + Mn is preferably 1 to 4, for example, but not limited to, 1.5, 2, 2.5, 3, 3.5, and the like.
In the above technical solution, in the catalyst in the step (1), the molar ratio of K to Co + Mn is preferably 2 to 5, for example, but not limited to, 2.5, 3, 3.5, 4, 4.5, and the like.
In the above-mentioned technical solutions, Co is preferably used in the form of cobalt acetate, Mn is preferably used in the form of manganese acetate, K is preferably used in the form of potassium bromide or potassium acetate, Br is preferably used in the form of an alkali metal bromide, preferably potassium bromide, and cobalt acetate is conveniently Co (OAc)2·4H2Calculated as O, manganese acetate Mn (OAc)2·4H2O, Br in KBr, K in KBr and CH3COOK is in total.
In the above technical solution, the mass ratio of the solvent to the catalyst in the step (1) is preferably 10 to 30, for example, but not limited to, the mass ratio of the solvent to the catalyst may be 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and the like, wherein the mass of the catalyst refers to the mass of elements Co, Mn, Br, and K, but not the mass of the compound.
In the above technical scheme, the mass ratio of the solvent to the 2, 6-naphthalenedicarboxylic acid in the step (1) is preferably 1000 to 5000, for example, but not limited to 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600, 3800, and the like, and more preferably 1000 to 3000.
In the above technical solution, the feeding speed of 2, 6-diisopropylnaphthalene in step (2) has a great effect on the oxidation effect, and although a high feeding rate can achieve a high yield, the purity of the obtained 2,6-naphthalene dicarboxylic acid is not high, and in order to achieve a high purity for the convenience of subsequent purification treatment, it is preferable that the space velocity of feeding 2, 6-diisopropylnaphthalene in step (2) is 0.0003-0.003 min/min relative to the mass of the solvent in the reaction kettle in step (1)-1For example, but not limited to, 2, 6-diisopropylnaphthalene feed space velocity of 0.00031min-1、0.00035min-1、0.00045min-1、0.00055min-1、0.00066min-1、0.00077min-1、0.0011min-1、0.0012min-1、0.0013min-1、0.0014min-1、0.0015min-1、0.0016min-1、0.0017min-1、0.0018min-1、0.0019min-1、0.002min-1、0.0021min-1、0.0022min-1、0.0023min-1、0.0024min-1、0.0025min-1、0.0026min-1、0.0027min-1、0.0028min-1、0.0029min-1And so on.
In the above technical solution, the ratio of the amount of the 2, 6-naphthalenedicarboxylic acid added in the step (1) to the amount of the 2, 6-diisopropylnaphthalene added in the step (2) is preferably more than 0 and 0.05 or less, for example, but not limited to, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.001, 0.0015, 0.002, 0.0025, 0.003, 0.0035, 0.004, 0.0045 and the like, and more preferably 0.0005 to 0.005, by weight.
In the above technical scheme, the temperature of the reaction in step (1) is preferably 160-220 ℃, such as but not limited to 165 ℃, 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃, 195 ℃, 200 ℃, 205 ℃, 210 ℃, 215 ℃, and the like, and more preferably 180-.
In the above technical scheme, the reaction pressure of step (1) is independently preferably 2 to 3MPa, such as but not limited to 2.1MPa, 2.2MPa, 2.3MPa, 2.4MPa, 2.5MPa, 2.6MPa, 2.7MPa, 2.8MPa, 2.9MPa and the like. In this case, the pressure is a gauge pressure.
The calculation formula of the yield of the 2,6-NDA in the invention is as follows:
yield ═ [ (molar amount of 2, 6-naphthalenedicarboxylic acid in the product-molar amount of 2, 6-naphthalenedicarboxylic acid initially charged)/molar amount of 2, 6-diisopropylnaphthalene fed ] × 100%.
The technical key point of the invention is that 2,6-naphthalene dicarboxylic acid is added in the step (1), and the yield of 2,6-NDA and the purity of 2,6-NDA are improved due to the adoption of the 2,6-naphthalene dicarboxylic acid; on the other hand, if the 2, 6-naphthalenedicarboxylic acid used in the step (1) is absent, such an excellent technical effect of the present invention cannot be achieved under the same reaction conditions.
The invention adopts the following components: mn: br: the catalyst proportion of K ═ 1:1:2:5 (molar ratio), acetic acid is used as solvent, the reaction temperature is 200 ℃, the reaction pressure is 2.75MPa, the mass ratio of 2, 6-diisopropyl naphthalene to solvent acetic acid is 0.0013min-1The reaction solution enters a reactor at the speed, air is introduced for reaction at the same time, and after the reaction is finished,the filter cake containing the 2, 6-naphthalenedicarboxylic acid is obtained by vacuum filtration, the obtained filter cake is washed by acetic acid, water and dried, the yield of the 2, 6-naphthalenedicarboxylic acid is 83.6 wt%, the purity is 98.2 wt%, and the difficulty is greatly reduced for subsequent separation and purification, so that better technical effects are obtained.
Detailed Description
[ example 1 ]
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the air is introduced for continuous reaction for 1h under the condition of maintaining the reaction temperature and the pressure, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, and is respectively washed by 60 ℃ acetic acid and 80 ℃ water, the amount of washing acetic acid is 1000g, the amount of washing water is 1000g, and after sampling and drying, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed, and the yield of the 2, 6.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 2 ]
166.05g Co (OAc)2·4H2O、81.7gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the reaction temperature and the pressure are maintained for continuous reaction for 1 hour, after the reaction is finished, reaction product mixed liquor containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, 60 ℃ acetic acid washing and 80 ℃ water washing are respectively adopted, the dosage of the washing acetic acid is 1000g, the dosage of the washing water is 1000g, and the 2, 6-naphthalenedicarboxylic acid obtained by sampling, drying and analyzing is usedThe purity of formic acid and the yield thereof were calculated.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 3 ]
83.03gCo (OAc)2·4H2O、163.4gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the reaction temperature and the pressure are maintained for continuous reaction for 1h, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, 60 ℃ acetic acid washing and 80 ℃ water washing are respectively adopted, the amount of washing acetic acid is 1000g, the amount of washing water is 1000g, and after sampling and drying, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed, and the yield of the obtained 2, 6-naphthalenedicarboxylic.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 4 ]
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK, 1g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the air is introduced for continuous reaction for 1h under the condition of maintaining the reaction temperature and the pressure, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, and is respectively washed by 60 ℃ acetic acid and 80 ℃ water, the washing acetic acid is 1000g, the washing water is 1000g, and after sampling and drying, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed, and the yield of the obtained 2, 6-naphthalenedicarboxylic.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 5 ]
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O, 297.5g of KBr, 40.45g of HBr, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled at 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to a molten state, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the reaction temperature and the pressure are maintained, air is introduced for continuous reaction for 1h, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, and the mixture is respectively washed by 60 ℃ of acetic acid and 80 ℃ of water, the amount of the washing acetic acid is 1000g, the amount of the washing water is 1000g, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed after sampling and drying, and the yield of.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 6 ]
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 15g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the air is introduced for continuous reaction for 1h under the condition of maintaining the reaction temperature and the pressure, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, and is respectively washed by 60 ℃ acetic acid and 80 ℃ water, the washing acetic acid is 1000g, the washing water is 1000g, and after sampling and drying, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed, and the yield of the obtained 2, 6-naphthalenedicarboxylic.
For convenience, the main process conditions and experimental results are listed in table 1.
[ example 7 ]
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O、119gKBr、294.4gCH3COOK, 2g of 2, 6-naphthalenedicarboxylic acid and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropylnaphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, 80L/min of air is introduced for reaction, after the feeding is finished, the air is introduced for continuous reaction for 1h under the condition of maintaining the reaction temperature and the pressure, after the reaction is finished, reaction product mixed liquid containing crude 2, 6-naphthalenedicarboxylic acid is subjected to vacuum filtration, and is respectively washed by 60 ℃ acetic acid and 80 ℃ water, the washing acetic acid is 1000g, the washing water is 1000g, and after sampling and drying, the purity of the obtained 2, 6-naphthalenedicarboxylic acid is analyzed, and the yield of the obtained 2, 6-naphthalenedicarboxylic.
For convenience, the main process conditions and experimental results are listed in table 1.
[ COMPARATIVE EXAMPLE 1 ]
The difference from example 1 is that 2,6-NDA is not added, as follows:
124.5g Co (OAc)2·4H2O、122.5gMn(OAc)2·4H2O、119gKBr、147.2gCH3COOK and 5000g of acetic acid are mixed and added into a reaction kettle, then stirring is started, the temperature is raised to 200 ℃, the pressure of the reaction kettle is controlled to be 2.75MPa, 1000g of 2, 6-diisopropyl naphthalene is heated to be molten, then the mixture enters the reaction kettle at the speed of 8g/min, simultaneously 80L/min of air is introduced for reaction, after the feeding is finished, the air is introduced for continuous reaction for 1 hour under the condition of maintaining the reaction temperature and the reaction pressure, after the reaction is finished, reaction product mixed liquor containing crude 2,6-naphthalene dicarboxylic acid is subjected to vacuum filtration, 60 ℃ acetic acid washing and 80 ℃ water washing are respectively adopted, the dosage of the washing acetic acid is 1000g, the dosage of the washing water is 1000g, and after sampling and drying, the purity of the obtained 2,6-naphthalene dicarboxylic acid is analyzed, and the yield of the 2.
For convenience, the main process conditions and experimental results are listed in table 1.
TABLE 1
Claims (10)
- The process of oxidizing 2, 6-diisopropyl naphthalene to prepare 2,6-naphthalene dicarboxylic acid includes the following steps:(1) adding a catalyst, a solvent and 2, 6-naphthalenedicarboxylic acid into a reaction kettle, controlling the temperature in the reaction kettle to be 160-220 ℃ and the reaction pressure to be 2-3 MPa;(2) adding 2, 6-diisopropyl naphthalene into the reaction kettle, and introducing gas containing free oxygen to react;(3) after the feeding of the 2, 6-diisopropyl naphthalene is finished, continuously reacting for 0.5 to 2 hours to obtain a product 2,6-naphthalene dicarboxylic acid mixture;the catalyst in the step (1) contains Co, Mn, Br and K.
- 2. The method of claim 1, wherein the free oxygen-containing gas is air.
- 3. The method according to claim 1, wherein the solvent in step (1) is independently selected from acetic acid and/or propionic acid.
- 4. The method as set forth in claim 1, wherein the molar ratio of Mn to Co in the catalyst in the step (1) is independently 0.5 to 2.
- 5. The method as set forth in claim 1, wherein in the catalyst of the step (1), the molar ratio of Br to Co + Mn is independently 1 to 4.
- 6. The method as set forth in claim 1, wherein in said catalyst of step (1), the molar ratio of K to Co + Mn is independently 2 to 5.
- 7. The method of claim 1, wherein the mass ratio of the solvent to the catalyst in the step (1) is 10 to 30.
- 8. The method according to claim 1, wherein the mass ratio of the solvent in the step (1) to the 2, 6-naphthalenedicarboxylic acid is 1000 to 5000.
- 9. The method as set forth in claim 1, wherein the space velocity of the fed 2, 6-diisopropylnaphthalene in the step (2) is 0.0003 to 0.003min relative to the mass of the solvent in the reaction vessel in the step (1)-1。
- 10. The process according to claim 1, wherein the ratio of the amount of the 2, 6-naphthalenedicarboxylic acid added in step (1) to the amount of the 2, 6-diisopropylnaphthalene added in step (2) is from 0 to 0.05, more preferably from 0.0005 to 0.005, by weight.
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| JPH06211733A (en) * | 1992-05-13 | 1994-08-02 | Osaka City | Production of 2,6-naphthalene dicarboxylic acid |
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| Title |
|---|
| 靳海波等: "《2,6-二异丙基萘液相空气氧化制2,6-萘二甲酸》", 《化工学报》 * |
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