A method for preparing pyromellitic acid by liquid phase oxidation of durene
By using transition metal ion catalysts such as Fe2+, Fe3+, Co2+, and Mn2+ and hydrogen peroxide as a co-oxidant, the problem of catalyst corrosion and contamination in the liquid-phase oxidation of mesitylene was solved, and high-yield and low-corrosion production of mesitylene tetracarboxylic acid was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-06-24
- Publication Date
- 2026-07-24
Smart Images
Figure BDA0003713639900000061
Abstract
Description
Technical Field
[0001] This invention relates to a method for oxidizing mesitylene to produce pyromellitic acid. Background Technology
[0002] Pyromellitic acid (1,2,4,5-phenylenetetracarboxylic acid, PMA) is an important organic raw material. Its dehydration product is pyromellitic dianhydride (PMDA). Pyromellitic dianhydride is one of the important precursors for the synthesis of polyimide (PI). PI is a special polymer material with outstanding performance and synthesis characteristics. Its enormous application prospects, whether as a structural or functional material, are well-recognized, with broad applications in electronics, aerospace, and biomedicine. It can be said that without polyimide, today's microelectronics technology would not exist. Therefore, the green production of pyromellitic acid is of great significance for the efficient synthesis of polyimide.
[0003] The synthesis of PMA generally involves the oxidation of mesitylene (1,2,4,5-tetramethylbenzene), which can be further divided into gas-phase and liquid-phase methods. Although the gas-phase method directly produces PMDA, the product purity is low, requiring hydrolysis to PMA for further purification. On the other hand, the liquid-phase oxidation method uses highly corrosive and hazardous catalysts, such as high-concentration nitric acid combined with transition metal ions or metal-bromine catalysts. These catalysts easily cause equipment corrosion and significant wastewater pollution.
[0004] US5041633 discloses a method for preparing pyromellitic acid (PMA) using a Co-Mn-Br homogeneous catalyst to catalytically oxidize mesitylene. The yield of PMA is approximately 80%, but the issues of catalyst recovery and equipment corrosion remain unresolved. Summary of the Invention
[0005] The present invention addresses the corrosion and contamination problem of bromine-containing catalysts in the existing liquid-phase oxidation method of mesitylene, and provides a method for producing pyromellitic acid by liquid-phase oxidation of mesitylene. This method has the advantages of weak corrosiveness of the reaction liquid, easy waste liquid treatment, and high yield of pyromellitic acid.
[0006] This invention provides a method for the liquid-phase oxidation of mesitylene to produce pyromellitic acid, comprising using transition metal ions as catalysts, hydrogen peroxide as a co-oxidant, and an O2-containing gas as an oxidant, to oxidize mesitylene to obtain pyromellitic acid.
[0007] In the above technical solution, the transition metal ions preferably include those selected from Fe. 2+ Fe 3+ Co 2+ Mn 2+At least one of the following, more preferably at least three or more metal ions, and preferably including Fe. 2+ Co 2+ and Mn 2+ ;of which Fe 2+ Co 2+ and Mn 2+ The molar ratio is 1:(0.2~2.5):(0.2~2.5). In the above technical solution, the transition metal ions are derived from the acetate solution of the transition metal. For example, but not limited to, ferrous acetate, ferric acetate, cobalt acetate, manganese acetate, etc.
[0008] In the above technical solution, the solvent used in the reaction includes acetic acid, wherein the mass concentration of acetic acid is 55% or more, preferably 55% to 95%, such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc.
[0009] In the above technical solution, the oxidant is air.
[0010] In the above technical solution, the molar ratio of the total amount of transition metal ions to mesitylene is 0.01 to 0.10, for example, but not limited to, the molar ratio of the total amount of transition metal ions to mesitylene is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, etc.
[0011] In the above technical solution, the molar ratio of the total amount of transition metal ions to hydrogen peroxide is 0.1 to 1.0, for example, but not limited to, the molar ratio of the total amount of metal ions to hydrogen peroxide is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.
[0012] In the above technical solution, the reaction temperature of the oxidation reaction is 120 to 270°C, for example, but not limited to, the oxidation reaction temperature is 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, etc.
[0013] In the above technical solution, the pressure of the oxidation reaction is 10-30 bar, for example, but not limited to, 12 bar, 14 bar, 16 bar, 18 bar, 20 bar, 22 bar, 24 bar, 26 bar, 28 bar, etc. The pressure can be adjusted by using an inert gas as a backup pressure for the adsorption system. For example, nitrogen can be used as a backup pressure.
[0014] In the above technical solution, the oxidation reaction time is 60 to 150 minutes, for example, but not limited to, the oxidation reaction time is 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, etc.
[0015] In the above technical solution, after the oxidation reaction is completed, the reaction solution is cooled to crystallize, and then the solid is filtered and dried at 80-150°C for 2-8 hours to obtain pyromellitic acid (PMA) product; preferably, the cooling temperature of the reaction solution is 10-60°C, for example, but not limited to, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, etc.
[0016] Compared with the prior art, the present invention has the following advantages:
[0017] The method for producing pyromellitic acid by liquid-phase oxidation of mesitylene provided by this invention overcomes the problems of corrosion of reaction equipment and environmental pollution caused by the addition of bromine to the reaction system in other methods. In this method, an oxidizing agent is added to the reaction solution to promote the oxidation of O2, and Fe is utilized... 2+ / Co 2+ / Mn 2+ The synergistic effect of the system improves the yield of pyromellitic acid. In particular, the reaction system can be made without Br, which reduces the corrosion of equipment and is more environmentally friendly. Detailed Implementation
[0018] The following examples will further illustrate the homogeneous catalyst synthesis method provided by the present invention, but the scope of protection of the present invention is not limited to these examples.
[0019] Example 1
[0020] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.19 mol Fe2+ over 60 min. 2+ 0.09 mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0021] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 100.0 mol.%, and the selectivity of PMA was 95.5 mol.%.
[0022] For ease of comparison, the experimental results are listed in Table 1.
[0023] Example 2
[0024] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.19 mol Fe2+ over 60 min. 3+ 0.09 mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0025] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 75.6 mol.%, and the selectivity of PMA was 93.5 mol.%.
[0026] For ease of comparison, the experimental results are listed in Table 1.
[0027] Example 3
[0028] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.46 mol hydrogen peroxide and 0.19 mol Fe2+ over 60 min. 2+ 0.09 mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0029] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 95.6 mol.%, and the selectivity of PMA was 92.6 mol.%.
[0030] For ease of comparison, the experimental results are listed in Table 1.
[0031] Example 4
[0032] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. The gas was then switched to air at a rate of 0.18 mol / min, followed by pumping in 1.85 mol of hydrogen peroxide and 0.19 mol of Fe over 60 min. 2+ 0.09 mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0033] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 100.0 mol.%, and the selectivity of PMA was 85.6 mol.%.
[0034] For ease of comparison, the experimental results are listed in Table 1.
[0035] Example 5
[0036] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the reactor. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.37 mol Fe2+ over 60 min. 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0037] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 82.3 mol.%, and the selectivity of PMA was 93.2 mol.%.
[0038] For ease of comparison, the experimental results are listed in Table 1.
[0039] Example 6
[0040] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the reactor. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.37 mol Fe2+ over 60 min. 3+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0041] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 70.1 mol.%, and the selectivity of PMA was 76.2 mol.%.
[0042] For ease of comparison, the experimental results are listed in Table 1.
[0043] Example 7
[0044] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen was introduced, maintaining a pressure of 20 bar inside the reactor. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.37 mol Co over 60 min. 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0045] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 90.2 mol.%, and the selectivity of PMA was 87.7 mol.%.
[0046] For ease of comparison, the experimental results are listed in Table 1.
[0047] Example 8
[0048] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the reactor. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.37 mol MnO over 60 min. 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0049] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 65.8 mol.%, and the selectivity of PMA was 69.3 mol.%.
[0050] For ease of comparison, the experimental results are listed in Table 1.
[0051] Example 9
[0052] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the reactor. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.09 mol Fe2+ over 60 min. 2+ 0.19mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0053] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 90.7 mol.%, and the selectivity of PMA was 91.5 mol.%.
[0054] For ease of comparison, the experimental results are listed in Table 1.
[0055] Example 10
[0056] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen was introduced, maintaining a pressure of 20 bar inside the tank. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol hydrogen peroxide and 0.12 mol Fe over 60 min. 2+ 0.12 mol Co 2+ and 0.13 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0057] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 92.3 mol.%, and the selectivity of PMA was 93.7 mol.%.
[0058] For ease of comparison, the experimental results are listed in Table 1.
[0059] Comparative Example 1 (D1)
[0060] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. Air was then introduced at a rate of 0.18 mol / min, followed by the pumping of 0.19 mol of Fe over 60 min. 2+ 0.09 mol Co 2+and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0061] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 43.5 mol.%, and the selectivity of PMA was 30.3 mol.%.
[0062] For ease of comparison, the experimental results are listed in Table 1.
[0063] Comparative Example 2 (D2)
[0064] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C in a stirred tank over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the tank. Subsequently, 0.74 mol of hydrogen peroxide and 0.19 mol of Fe were pumped in over 60 min. 2+ 0.09 mol Co 2+ and 0.09 mol Mn 2+ Meanwhile, the temperature was raised to 170℃ and the reaction was carried out for 120 minutes.
[0065] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 35.6 mol.%, and the selectivity of PMA was 63.2 mol.%.
[0066] Comparative Example 3 (D3)
[0067] 100 g of mesitylene (98 wt.%) was added to 400 g of acetic acid solvent. The mixture was gradually heated to 140 °C over 50 min while nitrogen gas was introduced, maintaining a pressure of 20 bar inside the reactor. The gas was then switched to air at a rate of 0.18 mol / min, followed by the pumping of 0.74 mol of hydrogen peroxide over 60 min, while the temperature was raised to 170 °C. The reaction was carried out for 120 min.
[0068] After the reaction was completed, the reaction solution was cooled at 15°C to crystallize. The solid was then filtered and dried in an oven at 100°C for 6 hours to obtain pyromellitic acid (PMA) product. The conversion rate of pyromellitic acid was 40.4 mol.%, and the selectivity of PMA was 1.2 mol.%.
[0069] For ease of comparison, the experimental results are listed in Table 1.
[0070] Table 1 Catalytic performance of each example and comparative example
[0071]
Claims
1. A method for liquid-phase oxidation of mesitylene to prepare pyromellitic acid, comprising using transition metal ions as catalysts, hydrogen peroxide as a co-oxidant, and an O2-containing gas as an oxidant, to oxidize mesitylene to obtain pyromellitic acid; The transition metal ion is Fe. 2+ Co 2+ and Mn 2+ ;of which Fe 2+ Co 2+ and Mn 2+ The molar ratio is 1:(0.2~2.5):(0.2~2.5).
2. The method according to claim 1, characterized in that, The transition metal ions are derived from the acetate of the transition metal; the solvent used in the reaction is acetic acid; and the oxidant is air.
3. The method according to claim 1, characterized in that, The molar ratio of the total amount of transition metal ions to mesitylene is 0.01 to 0.
1.
4. The method according to claim 1, characterized in that, The total amount of transition metal ions and the molar ratio of hydrogen peroxide are 0.1 to 1.
5. The method according to claim 1, characterized in that, The oxidation reaction temperature is 120~270℃; the oxidation reaction pressure is 10~30 bar; and the oxidation reaction time is 60~150 min.
6. The method according to claim 1, characterized in that, After the oxidation reaction is completed, the reaction solution is cooled to crystallize, and then the solid is filtered and dried at 80~150℃ for 2~8 h to obtain pyromellitic acid product.
7. The method according to claim 6, characterized in that, The reaction solution is cooled at a temperature of 10~60℃.