Method for purifying pyroxenic acid

Abstract

The invention relates to a method for purifying pyroxenic acid, which mainly solves the technical problem of low pyroxenic acid yield in the prior art method for purifying crude pyroxenic acid. The invention adopts a method for purifying pyroxenic acid, comprising the steps of treating a solution containing crude PMA with activated carbon adsorption, and adding an auxiliary agent to the solution containing crude PMA, wherein the auxiliary agent is a polyol with a carbon number of 4 or less in the molecule. The technical solution effectively solves the technical problem and can be used in the purification production of crude pyroxenic acid.

Description

Technical Field

[0001] The present invention relates to a method for purifying pyroxenic acid. Background Art

[0002] Pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid, PMA) is an important organic raw material. Its dehydration product is pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid dianhydride, PMDA). Pyromellitic dianhydride is a key precursor for the synthesis of polyimide (PI). PI is a specialty polymer with outstanding performance and synthesis characteristics. Its vast application prospects, both as a structural and functional material, are well-recognized. It is considered a "problem solver," and it is believed that without polyimide, today's microelectronics technology would not exist. Therefore, the production of high-purity pyromellitic acid is of great significance for the efficient synthesis of polyimide.

[0003] The most common method for synthesizing PMA is the oxidation of durene (1,2,4,5-tetramethylbenzene), which is categorized into two types: gas-phase and liquid-phase methods. While the gas-phase method directly produces PMDA, due to its low purity, it still requires hydrolysis to PMA and subsequent purification. The liquid-phase method, on the other hand, produces PMA as an oxidation product, but since the metal ions and byproducts in the homogeneous reaction are dissolved in the solution, the purification step is still crucial. Therefore, efficient and high-yield PMA purification methods are crucial to meet the demand for high-purity PMA production.

[0004] Amoco Corporation published patent US 5041633 (Process for the Production of An Aromatic Polycarboxylic Acid). Published on August 20, 1991, the patent describes a method for preparing pyromellitic acid (PMA). The method employs activated carbon and cationic resins to adsorb impurities from a crude PMA solution to purify the PMA. While the patent utilizes multiple adsorbents to remove impurities, effectively improving the purity of the PMA, the adsorption process results in significant PMA product loss and the resin is difficult to recover, significantly increasing process costs. Summary of the Invention

[0005] The present invention aims to solve the technical problem of low yield of pyroxenic acid in the prior art purification method of crude pyroxenic acid, and provides a new method for purifying pyroxenic acid, which has the advantage of high yield of pyroxenic acid.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] The method for purifying pyroxene tetrabenzoic acid comprises the steps of treating a solution containing crude PMA with activated carbon adsorption, wherein an auxiliary agent is added to the solution containing crude PMA, and the auxiliary agent is a polyol with a carbon number of 4 or less in the molecule.

[0008] By adding the auxiliary agent to the solution containing crude PMA, the yield of the refined PMA product is improved.

[0009] Non-limiting examples of the auxiliary agent include, but are not limited to, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, and the like.

[0010] In the above technical solution, the solvent of the solution preferably includes at least one of the group consisting of water and acetic acid.

[0011] In the above technical solution, the mass ratio of the auxiliary agent to the activated carbon is preferably 1 to 10. For example, but not limited to, the mass ratio of the auxiliary agent to the activated carbon is 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, etc.

[0012] In the above technical solution, the mass ratio of activated carbon to crude PMA is preferably 0.005 to 0.05, for example but not limited to 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, etc.

[0013] In the above technical solution, the purity of the crude PMA is preferably 50.0-90.0 wt.%, for example, but not limited to, the purity of the crude PMA is 55.0 wt.%, 60.0 wt.%, 65.0 wt.%, 70.0 wt.%, 75.0 wt.%, 80.0 wt.%, 85.0 wt.%, etc.

[0014] In the above technical solution, the concentration of crude PMA in the crude PMA-containing solution is preferably 10-30 wt.%. For example, but not limited to, the concentration of crude PMA in the crude PMA-containing solution is 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.%, and the like.

[0015] In the above technical solution, the adsorption treatment time is preferably 60 to 120 minutes, for example but not limited to 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, etc.

[0016] In the above technical solution, the temperature of the adsorption treatment is preferably 60-95° C. For example, but not limited to, the temperature of the adsorption treatment is 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., etc.

[0017] In the above technical solution, the adsorption treatment pressure is preferably 1-1.5 MPa. For example, but not limited to, the adsorption treatment pressure is 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, etc. The pressure can be adjusted by using a gas that is inert to the adsorption system, such as nitrogen.

[0018] In the above technical solution, it is preferred that after the solution containing crude PMA is treated with activated carbon adsorption, the process includes filtering and freezing and crystallizing the filtrate to obtain refined PMA.

[0019] In the above technical solution, the crystallization temperature is preferably 5 to 15° C. For example, but not limited to 6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C., etc. More preferably, 6 to 13° C. The freezing crystallization time is preferably 0.5 to 2 hours, for example, but not limited to, the crystallization time in step (II) is 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour, 1.0 hour, 1.1 hour, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, etc.

[0020] The source of crude PMA is not particularly limited. For example, the source of crude PMA can be obtained by liquid-phase oxidation of durenyl in acetic acid solvent with Co / Mn / Br as a catalyst at 170-230°C to produce a crude PMA solution, followed by solid-liquid separation through cooling and crystallization, and drying the solid to obtain crude PMA; or by vaporizing durenyl above 300°C and vapor-phase oxidizing it with a V2O5 catalyst to produce pyromellitic dianhydride, which is then hydrolyzed to produce a crude PMA solution, followed by solid-liquid separation through cooling and crystallization, and drying the solid to obtain crude PMA; or by liquid-phase alkylation of trimethylolbenzene followed by oxidation, similarly followed by crystallization to separate the solid, and drying to obtain crude PMA. However, for the sake of comparison, the specific source of crude PMA in a specific embodiment of the present invention is: liquid-phase oxidation of durenyl with Co / Mn / Br as a homogeneous catalyst at 170-230°C to produce a crude PMA solution, followed by solid-liquid separation through cooling and crystallization, and drying the solid to obtain crude PMA.

[0021] The present invention is described in detail below through specific embodiments. DETAILED DESCRIPTION

[0022] Example 1

[0023] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of >99.0 wt.% and a yield of 98.7%.

[0024] For comparison purposes, the experimental results are listed in Table 1.

[0025] Example 2

[0026] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of glycerol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of 98.6 wt.% and a yield of 97.5%.

[0027] For comparison purposes, the experimental results are listed in Table 1.

[0028] Example 3

[0029] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water. 5 g of activated carbon (Norit SG III) and 10 g of 1,2-propylene glycol were then added. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of 97.6 wt.% and a yield of 96.8%.

[0030] For comparison purposes, the experimental results are listed in Table 1.

[0031] Example 4

[0032] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water. 5 g of activated carbon (Norit SG III) and 10 g of 1,3-propylene glycol were then added. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of 98.5 wt.% and a yield of 97.5%.

[0033] For comparison purposes, the experimental results are listed in Table 1.

[0034] Example 5

[0035] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 5 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of 96.8 wt.% and a yield of 95.1%.

[0036] For comparison purposes, the experimental results are listed in Table 1.

[0037] Example 6

[0038] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 25 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of >99.0 wt.%, for a yield of 98.2%.

[0039] For comparison purposes, the experimental results are listed in Table 1.

[0040] Example 7

[0041] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of acetic acid, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to yield the refined PMA product with a purity of 95.3 wt.% and a yield of 94.1%.

[0042] For comparison purposes, the experimental results are listed in Table 1.

[0043] Example 8

[0044] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to yield the refined PMA product with a purity of 98.5 wt.%, for a yield of 97.2%.

[0045] For comparison purposes, the experimental results are listed in Table 1.

[0046] Example 9

[0047] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of ethylene glycol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.5 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to yield the refined PMA product with a purity of 98.8 wt.% and a yield of 97.7%.

[0048] For comparison purposes, the experimental results are listed in Table 1.

[0049] Comparative Example 1

[0050] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of pure water. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to obtain the refined PMA product with a purity of 89.1 wt.% and a yield of 83.6%.

[0051] For comparison purposes, the experimental results are listed in Table 1.

[0052] Comparative Example 2

[0053] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of ethanol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to yield the refined PMA product with a purity of 89.5 wt.% and a yield of 83.7%.

[0054] For comparison purposes, the experimental results are listed in Table 1.

[0055] Comparative Example 3

[0056] 100 g of crude PMA with a purity of 85.1 wt.% was dissolved in 400 g of pure water, followed by the addition of 5 g of activated carbon (Norit SG III) and 10 g of sorbitol. The suspension was stirred in a hydrothermal autoclave, nitrogen was introduced to maintain the autoclave pressure at 1.3 MPa, and the temperature was raised to 90°C for adsorption for 1 hour. The autoclave was then vented to atmospheric pressure, filtered while still hot, and the activated carbon removed. The filtrate was cooled to 10°C, allowed to crystallize for 1 hour, filtered, and the filter cake rinsed with pure water until the filtrate was neutral. The filter cake was dried at 100°C for 6 hours to yield the refined PMA product with a purity of 88.3 wt.%, for a yield of 82.1%.

[0057] For comparison purposes, the experimental results are listed in Table 1.

[0058] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

[0059] Table 1

[0060]

Claims

1. A method for purifying pyroxene tetrabenzoic acid, comprising the steps of treating a solution containing crude PMA with activated carbon adsorption, adding an auxiliary agent to the crude PMA solution, wherein the auxiliary agent is a polyol having 4 or fewer carbon atoms in the molecule, and the solvent of the solution is water, acetic acid, or a combination of water and acetic acid.

2. The method according to claim 1, wherein The solvent of the solution is composed of water and acetic acid.

3. The method according to claim 1, wherein The mass ratio of the auxiliary agent to the activated carbon is 1 to 10.

4. The method according to claim 1, wherein The mass ratio of activated carbon to crude PMA is 0.005~0.

05.

5. The method according to claim 1, wherein The purity of crude PMA is 50.0~90.0wt.%.

6. The method according to claim 1, wherein The concentration of crude PMA in the crude PMA-containing solution is 10-30 wt.%.

7. The method according to claim 1, wherein The adsorption treatment time is 60~120 min.

8. The method according to claim 1, wherein The adsorption temperature is 60~95 o C.

9. The method according to claim 1, wherein The pressure of adsorption treatment is 1~1.5 MPa.

10. The method according to claim 1, wherein The method comprises the steps of filtering the solution containing crude PMA by adsorption with activated carbon, and performing freeze crystallization on the filtrate to obtain refined PMA.

Images