A method for reducing the by-product phenazine in the RT-ferment condensate
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-24
- Publication Date
- 2026-06-26
AI Technical Summary
The existing RT-based condensation reaction produces a high amount of phenazine byproducts and has low selectivity, leading to increased raw material consumption and decreased RT-based condensation quality.
Adding ammonia water to modified activated carbon during the condensation reaction increases the basic functional groups of the activated carbon, reduces the attack of aniline ions on the ortho-position of nitrobenzene, adsorbs acidic substances in the system, and extends the service life of the catalyst.
It reduces the formation of phenazine byproducts in RT-Pyrus condensation solution, improves the selectivity of condensation reaction, reduces raw material consumption, extends catalyst life and reduces cost.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemical technology, specifically relating to a method for reducing phenazine, a byproduct, in RT pyrolysis condensate. Background Technology
[0002] RT-p-aminodiphenylamine (RTP) is widely used in rubber additives, dyes, textiles, printing, and pharmaceutical industries, primarily as an antioxidant in rubber products such as 4010NA and 6PPD. Currently, the domestic nitrobenzene method for preparing RT-p ...
[0003] The reaction mechanism of the condensation reaction is as follows: aniline combines with the phase transfer catalyst tetramethylammonium hydroxide to generate aniline ions. The aniline ions act as nucleophiles to attack the para position of nitrobenzene, resulting in intramolecular oxidation to generate 4-nitrosodiphenylamine. The 4-nitrosodiphenylamine is then intermolecularly oxidized by nitrobenzene to generate 4-nitrosodiphenylamine and nitrosobenzene. The nitrosobenzene and aniline react to generate the byproduct azobenzene. The aniline ions act as nucleophiles to attack the ortho position of nitrobenzene to generate the byproduct phenazine. The process of phenazine formation is as follows.
[0004]
[0005] Chinese patent CN1285566C discloses a zeolite carrier with alkali material for the coupling of aniline and nitrobenzene. Aniline and nitrobenzene react on ZSM-5 zeolite loaded with tetramethylammonium hydroxide. The cross-sectional size of the pores inside the zeolite maintains a restricted transition state in the reaction of aniline and nitrobenzene to obtain the 4-aminodiphenylamine intermediate, and improves the selectivity of the 4-aminodiphenylamine intermediate. ZSM-5 zeolite is a novel zeolite molecular sieve containing organic amine cations, possessing adsorption properties, thermal stability, acid resistance, water vapor stability, and hydrophobicity. However, it is soluble in strong alkalis, and tetramethylammonium hydroxide is a strong organic alkali that dissolves the aluminum element in ZSM-5 zeolite, destroying its crystal structure and thus affecting the reaction selectivity. Therefore, the alkali-supported ZSM-5 zeolite cannot be used continuously or recycled for the coupling reaction of aniline and nitrobenzene. Summary of the Invention
[0006] The purpose of this invention is to provide a method for reducing the amount of phenazine byproduct in RT-based condensation solutions, aiming to solve the problems of high phenazine byproduct formation and low selectivity in existing RT-based condensation reactions, reduce the consumption of aniline and nitrobenzene raw materials, and improve the quality of RT-based condensation solutions.
[0007] This invention discloses a method for reducing the byproduct phenazine in RT-Pyrate condensation solution. Ammonia-modified activated carbon is added during the condensation reaction. The ammonia-modified activated carbon increases the basicity of its functional groups, reducing the activity of aniline ions adsorbed on the ammonia-modified activated carbon in attacking the ortho-position of nitrobenzene. This reduces the formation of phenazine by aniline salt attacking the ortho-position of nitrobenzene. Simultaneously, the ammonia-modified activated carbon adsorbs acidic substances in the system material, slowing the increase of tetramethylammonium salt and extending the catalytic lifetime of tetramethylammonium hydroxide.
[0008] The present invention is achieved as follows: a method for reducing the byproduct phenazine in RT condensation solution, characterized by adding ammonia-modified activated carbon during the condensation reaction.
[0009] Generally, the amount of activated carbon modified by ammonia is 80% to 100% of the amount of nitrobenzene added in the condensation reaction.
[0010] Generally, the method of the present invention for reducing the byproduct phenazine in RT-based condensation solution involves introducing tetramethylammonium hydroxide, aniline, nitrobenzene, and ammonia-modified activated carbon into a condensation reactor. The tetramethylammonium hydroxide catalyzes the condensation reaction of aniline and nitrobenzene to obtain a condensation solution. The ammonia-modified activated carbon and the condensation solution are then separated. The ammonia-modified activated carbon is used in the condensation reaction, and the condensation solution is catalytically hydrogenated to prepare RT-based condensation solution.
[0011] The ammonia-modified activated carbon treatment steps are as follows: 1) Boil the activated carbon in deionized water for 0.5~2.0h; 2) Rinse the boiled activated carbon with deionized water; 3) Dry the rinsed activated carbon at a drying temperature of 100℃~115℃; 4) Immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 6%~18% and stir in a sealed container for 1h~3h; 5) Rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; 6) Dry the ammonia-treated and rinsed activated carbon at a constant temperature of 80℃~100℃ to obtain ammonia-modified activated carbon.
[0012] The aniline is fresh aniline and / or recycled aniline, and the tetramethylammonium hydroxide is fresh tetramethylammonium hydroxide and / or recycled tetramethylammonium hydroxide.
[0013] The condensation reaction temperature is 60℃~80℃.
[0014] The condensation reaction is carried out under a certain vacuum, with a vacuum pressure of -0.088MPa to -0.094MPa.
[0015] Compared with the prior art, the present invention has the following advantages: 1. By using ammonia-modified activated carbon, the formation of phenazine byproduct in the RT-Pyrate condensation solution can be reduced, thereby improving the selectivity of the RT-Pyrate condensation reaction; 2. Ammonia-modified activated carbon can protect the condensation reaction catalyst tetramethylammonium hydroxide, improve the catalyst's lifespan and selectivity, reduce the conversion of tetramethylammonium hydroxide to tetramethyl carbonate, and lower raw material costs. Detailed Implementation
[0016] The present invention will now be described in detail with reference to the embodiments (all percentages below are mass percentages).
[0017] Comparative example (activated carbon modified without ammonia) 59.2 g of a 25% solution of fresh tetramethylammonium hydroxide, 75.0 g of fresh aniline, and 20.0 g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.092 MPa and the reaction temperature at 70 °C for a condensation reaction. The condensation reaction time was 4 h to obtain a condensate. The contents of each substance in the condensate were analyzed by liquid chromatography: aniline 47.35%, nitrobenzene 0.30%, 4-nitrosodiphenylamine 28.88%, 4-nitrodiphenylamine 2.69%, azobenzene 2.17%, and phenazine 0.25%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 92.26%, the selectivity of phenazine was 0.81%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.81%. Example 1
[0018] Preparation of ammonia-modified activated carbon: Boil activated carbon in deionized water for 1.0 h; rinse the boiled activated carbon with deionized water; dry the rinsed activated carbon at 105℃; immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 10% and stir in a sealed container for 2 h; rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; dry the ammonia-treated and rinsed activated carbon at a constant temperature of 95℃ to obtain ammonia-modified activated carbon.
[0019] 20g of the ammonia-modified activated carbon, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of fresh aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.092MPa and the reaction temperature at 70℃ for a condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 46.98%, nitrobenzene 0.25%, 4-nitrosodiphenylamine 30.17%, 4-nitrodiphenylamine 2.33%, azobenzene 1.78%, and phenazine 0.04%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.23%, the selectivity of phenazine was 0.13%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.18%. Example 2
[0020] Preparation of ammonia-modified activated carbon: Boil activated carbon in deionized water for 0.5 h; rinse the boiled activated carbon with deionized water; dry the rinsed activated carbon at 115 °C; immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 15% and stir in a sealed container for 1.5 h; rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; dry the ammonia-treated and rinsed activated carbon at a constant temperature of 100 °C to obtain ammonia-modified activated carbon.
[0021] 20g of the ammonia-modified activated carbon, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of fresh aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.094MPa and the reaction temperature at 65℃ for a condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.15%, nitrobenzene 0.27%, 4-nitrosodiphenylamine 30.21%, 4-nitrodiphenylamine 2.23%, azobenzene 1.75%, and phenazine 0.03%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.34%, the selectivity of phenazine was 0.09%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.16%. Example 3
[0022] Preparation of ammonia-modified activated carbon: Boil activated carbon in deionized water for 1.5 h; rinse the boiled activated carbon with deionized water; dry the rinsed activated carbon at 110℃; immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 6% and stir in a sealed container for 3.0 h; rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; dry the ammonia-treated and rinsed activated carbon at a constant temperature of 100℃ to obtain ammonia-modified activated carbon.
[0023] 16g of the ammonia-modified activated carbon prepared above, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of recovered aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.093MPa and the reaction temperature at 68℃ for condensation reaction for 4 hours. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 46.32%, nitrobenzene 0.28%, 4-nitrosodiphenylamine 30.33%, 4-nitrodiphenylamine 2.19%, azobenzene 1.79%, and phenazine 0.05%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.18%, the selectivity of phenazine was 0.16%, and the tetramethyl carbonate content after 5 reuses of tetramethylammonium hydroxide was 0.19%. Example 4
[0024] Preparation of ammonia-modified activated carbon: Boil activated carbon in deionized water for 2.0 h; rinse the boiled activated carbon with deionized water; dry the rinsed activated carbon at 100℃; immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 18% and stir in a sealed container for 1.0 h; rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; dry the ammonia-treated and rinsed activated carbon at a constant temperature of 80℃ to obtain ammonia-modified activated carbon.
[0025] 20g of the ammonia-modified activated carbon, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of fresh aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.092MPa and the reaction temperature at 70℃ for a condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.19%, nitrobenzene 0.24%, 4-nitrosodiphenylamine 30.28%, 4-nitrodiphenylamine 2.21%, azobenzene 1.72%, and phenazine 0.03%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.44%, the selectivity of phenazine was 0.09%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.13%. Example 5
[0026] 18g of ammonia-modified activated carbon prepared in Example 4, 59.2g of 25% recovered tetramethylammonium hydroxide solution, 75.0g of recovered aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.092MPa and the reaction temperature at 70℃ for condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 46.25%, nitrobenzene 0.28%, 4-nitrosodiphenylamine 30.13%, 4-nitrodiphenylamine 2.20%, azobenzene 1.79%, and phenazine 0.04%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.18%, the selectivity of phenazine was 0.13%, and the tetramethyl carbonate content after 5 reuses of tetramethylammonium hydroxide was 0.15%. Example 6
[0027] 20g of ammonia-modified activated carbon prepared in Example 4, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of fresh aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.094MPa and the reaction temperature at 68℃ for condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.17%, nitrobenzene 0.23%, 4-nitrosodiphenylamine 30.24%, 4-nitrodiphenylamine 2.22%, azobenzene 1.73%, and phenazine 0.03%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.41%, the selectivity of phenazine was 0.09%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.16%. Example 7
[0028] Preparation of ammonia-modified activated carbon: Boil activated carbon in deionized water for 1.5 h; rinse the boiled activated carbon with deionized water; dry the rinsed activated carbon at 105 °C; immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 15% and stir in a sealed container for 2.0 h; rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; dry the ammonia-treated and rinsed activated carbon at a constant temperature of 95 °C to obtain ammonia-modified activated carbon.
[0029] 20g of the ammonia-modified activated carbon, 59.2g of fresh tetramethylammonium hydroxide 25% solution, 75.0g of fresh aniline, and 20.0g of nitrobenzene were added to a reactor. The reaction vacuum pressure was controlled at -0.092MPa and the reaction temperature at 69℃ for a condensation reaction. The condensation reaction time was 4h. After the reaction, the ammonia-modified activated carbon and the condensation liquid were separated. The organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.18%, nitrobenzene 0.24%, 4-nitrosodiphenylamine 30.29%, 4-nitrodiphenylamine 2.24%, azobenzene 1.75%, and phenazine 0.02%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 94.39%, the selectivity of phenazine was 0.06%, and the tetramethyl carbonate content after 5 cycles of tetramethylammonium hydroxide was 0.15%.
[0030] This invention can be summarized in other specific forms that do not depart from the spirit or essential features of the invention. Therefore, in all respects, the above embodiments of the invention should be considered illustrative only and not limiting, while the claims define the scope of the invention. The foregoing description does not define the scope of the invention; therefore, any changes within the meaning and scope equivalent to the claims should be considered to be included within the scope of the claims.
Claims
1. A method for reducing the amount of phenoxazine by-product in a RT- PEST condensate, characterized by Ammonia-modified activated carbon is added to the condensation reaction.
2. The method of claim 1, wherein the reducing of the byproduct phenazine in the RT- PEST condensate is characterized by The amount of activated carbon modified with ammonia water added is 80% to 100% of the amount of nitrobenzene added in the condensation reaction. 3. The method of claim 1 or 2, wherein the reducing of the by-product phenazine in the RT- PEST condensate is characterized by Tetramethylammonium hydroxide, aniline, nitrobenzene, and ammonia-modified activated carbon are introduced into a condensation reactor. Tetramethylammonium hydroxide catalyzes the condensation reaction of aniline and nitrobenzene to obtain a condensation liquid. The ammonia-modified activated carbon and the condensation liquid are separated. The ammonia-modified activated carbon is then used in the condensation reaction. The condensation liquid is then catalytically hydrogenated to prepare RT-based products.
4. The method of claim 1 or 2, wherein the reducing of the byproduct phenazine in the RT- PEST condensate is characterized by The ammonia-modified activated carbon treatment steps are as follows: 1) Boil the activated carbon in deionized water for 0.5~2.0h; 2) Rinse the boiled activated carbon with deionized water; 3) Dry the rinsed activated carbon at a drying temperature of 100℃~115℃; 4) Immerse the dried activated carbon in a prepared ammonia solution with an ammonia concentration of 6%~18% and stir in a sealed container for 1h~3h; 5) Rinse the ammonia-treated activated carbon with deionized water until the pH value is 7; 6) Dry the ammonia-treated and rinsed activated carbon at a constant temperature of 80℃~100℃ to obtain ammonia-modified activated carbon.
5. The method of claim 3, wherein the reducing of the byproduct phenazine in the RT- PEST condensate is characterized by The aniline is fresh aniline and / or recycled aniline, and the tetramethylammonium hydroxide is fresh tetramethylammonium hydroxide and / or recycled tetramethylammonium hydroxide. 6. The method of claim 3, wherein the reducing of the byproduct phenazine in the RT- PEST condensate is characterized by The condensation reaction temperature is 60℃~80℃.
7. The method of claim 3, wherein the reducing of the byproduct phenazine in the RT- PEST condensate is characterized by The condensation reaction was carried out under a vacuum pressure of -0.088 MPa to -0.094 MPa.