A method for removing impurities and recycling waste catalyst of aniline-nitrobenzene condensation reaction

Abstract

The present application relates to rubber antioxidant intermediate p-aminodiphenylamine production field, especially disclose a kind of aniline-nitrobenzene condensation reaction waste catalyst impurity removal recovery method.The present application is directed to the condensation reaction system of aniline and nitrobenzene in waste catalyst containing impurity characteristics, by sequentially adding phenolic compound and aldehyde compound, make it and organic amine impurities occur condensation polymerization in the alkaline environment of feed liquid itself, and then generate macromolecular organic matter precipitation, simultaneously aldehyde compound and excess phenolic compound can also occur polymerization and generate macromolecular chain phenol formaldehyde resin from system precipitation.The catalyst impurity removal effect of the present application is good, and the recovery rate is high;The additive used in treatment process is widely sourced, low cost, saves a large amount of adsorbent;Effectively avoid the use of extraction solvent, reduce the pressure of subsequent rectification operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rubber antioxidant intermediate p-aminodiphenylamine production, in particular to a method for removing impurities and recycling waste catalysts in aniline-nitrobenzene condensation reaction. BACKGROUND

[0002] The preparation reaction of p-phenylenediamine rubber antioxidant important intermediate p-aminodiphenylamine (RT-Perse) is carried out in two steps: first, aniline and nitrobenzene are condensed in the presence of a condensation catalyst to generate a condensate containing p-nitro diphenylamine and p-nitroso diphenylamine; then the condensate is subjected to catalytic hydrogenation to generate p-aminodiphenylamine.

[0003] The catalyst used in the condensation reaction of aniline and nitrobenzene is mainly a phase transfer catalyst such as tetramethylammonium hydroxide. The catalyst is continuously separated, recovered and recycled in the reaction system. With the increase of recovery and recycling times, the concentration of quaternary ammonium base in the catalyst phase gradually decreases, the content of carbonate gradually increases, and the content of organic impurities gradually increases. When the catalyst is returned to the reaction system for use, it will cause a decrease in reaction selectivity, an increase in side reactions, and a decrease in product quality. Therefore, a portion of the waste condensation catalyst liquid containing impurities is regularly discharged from the system in the actual production process, which not only increases the consumption of catalyst, but also produces a large amount of waste liquid, causing secondary pollution.

[0004] In order to remove impurities from the waste condensation catalyst liquid and recycle it, some production processes use activated carbon or adsorption resin to adsorb organic impurities in the catalyst, but there are obvious drawbacks in adsorption and impurity removal: activated carbon adsorption is non-selective adsorption, which will adsorb a part of quaternary ammonium base while removing organic impurities, causing loss of catalyst, and the saturated activated carbon is not easy to regenerate, not only causing high operating cost, but also producing waste activated carbon which is difficult to handle, forming secondary pollution; and the adsorption resin is expensive, and the composition of organic impurities in the system is complex, which will greatly shorten the service life of the resin, increase the consumption of the resin, and lead to high treatment cost. In addition, the resin that has reached its service life and cannot be regenerated will produce a large amount of solid waste, which is difficult to handle.

[0005] And in the electronic manufacturing industry of liquid crystal, semiconductor and other fields with large amount of tetramethylammonium hydroxide, the impurities in the used tetramethylammonium hydroxide are mainly macromolecular photoresist and the like, and the recovery process mainly includes the steps of neutralizing the acid to precipitate the impurities, filtering and removing the impurities to purify. However, in the condensation reaction system of aniline and nitrobenzene, the organic impurities are mainly organic amine, semi-oxidized quinone and their oxidation and polymerization products, and the types of impurities are complex. When the waste catalyst is rich in organic impurities, there are still a large amount of dissolved impurities in the system after the acid neutralization, and it is difficult to fully remove the impurities in the waste catalyst liquid by the method of simply neutralizing the acid to precipitate the impurities, and the inorganic acid used for adjusting the pH will also be mixed into the catalyst system, which will adversely affect the condensation and hydrogenation reactions when returning to the production system for reuse. Some process methods also propose to remove the organic impurities in the waste catalyst by extraction, but this method inevitably consumes a large amount of fresh extractant (aniline, etc.), and the oil phase after extraction is integrated into the subsequent rectification section, which not only greatly increases the rectification separation load, but also causes the extracted impurities to continue to coke under high temperature conditions in the rectification tower, thereby blocking various pipelines or heat exchanger components.

[0006] Therefore, it is urgent to develop a new process method for removing impurities and recycling the waste tetramethylammonium hydroxide condensation catalyst liquid, which is of great significance to the high-quality and high-efficiency production of RT-pest. SUMMARY

[0007] The present application provides a simple, efficient, environmentally friendly and economical method for removing impurities and recycling waste catalysts of aniline-nitrobenzene condensation reaction.

[0008] The present application is realized by the following technical solutions:

[0009] A method for removing impurities and recycling waste catalysts of aniline-nitrobenzene condensation reaction, which uses waste catalyst liquid after recycling of aniline-nitrobenzene condensation reaction as the treatment object, and includes the following steps:

[0010] (1) The waste catalyst liquid is transported to a pressure-resistant reaction kettle, and after heating and stirring, a phenolic additive A is added for reaction, and then an aldehyde additive B is added for further reaction. After the reaction, carbon dioxide is introduced, and after mixing under pressure and stirring, the pressure is reduced, and the carbon dioxide is recovered;

[0011] (2) The liquid treated in step (1) is moved from the reaction kettle to a tank for standing and precipitation, so that the precipitated organic impurities can be fully settled. The upper liquid after the impurities are separated by sedimentation is directly returned to the reaction kettle, and the lower impurities are filtered, and the filtrate is reacted in the reaction kettle;

[0012] (3) The salt alkali conversion agent X is added into the reactor, and the reaction is carried out by heating and stirring. After the reaction is completed, the temperature is lowered, the mixed liquid is removed from the reactor, and is sent to the filter for filtration. The obtained filtrate is sent to the concentration section, and is recycled as the recovered condensation catalyst.

[0013] The impurities in the condensation reaction system of aniline and nitrobenzene mainly include organic amine, semi-oxidized quinone and their oxidation and polymerization products, and the composition is complex. If the acid neutralization method is simply used, the amount of organic impurities separated is limited due to the pH change of the solution system, and a large amount of organic impurities is still dissolved in the mixed liquid and is difficult to separate. The present application is aimed at the characteristics of the impurities contained in the waste catalyst in the condensation reaction system of aniline and nitrobenzene. By sequentially adding phenolic compounds and aldehyde compounds, the condensation reaction of the organic amine impurities is carried out in the alkaline environment of the liquid itself, and macromolecular organic matter is generated and separated. At the same time, the aldehyde compounds and excess phenolic compounds can also undergo polymerization reaction to generate macromolecular phenolic aldehyde resin and separate from the system, which not only eliminates the residual phenolic and aldehyde aids in the system, but also plays a role in absorbing and adsorbing organic impurities. The adjustment of the pH of the liquid by the neutralization of the quaternary ammonium base by carbon dioxide makes the organic impurities further react and separate. Finally, the tetramethylammonium hydroxide is regenerated by the reaction of the salt forming agent and tetramethylammonium carbonate / tetramethylammonium bicarbonate, and the generated carbonate can be used as an adsorbent to further adsorb and remove impurities from the liquid.

[0014] The more technical solutions of the present application are:

[0015] In step (1), the phenolic aid A is one or more of m-dihydroxybenzene, p-dihydroxybenzene and o-dihydroxybenzene, and the aldehyde aid B is one of formaldehyde, acetaldehyde, glyoxal and propyl aldehyde.

[0016] Further preferably, the mass ratio of the catalyst liquid, the phenolic aid A and the aldehyde aid B is 1:0.0001-0.005:0.0001-0.005.

[0017] More preferably, after the phenolic aid A and the aldehyde aid B are added, the reaction temperature of the liquid is 40-80℃, and the reaction time is 0.5-5h.

[0018] Still more preferably, the pressure of the carbon dioxide is 0.1-5MPa, the stirring reaction time is 0.5-5h, and the salt forming rate of tetramethylammonium hydroxide is controlled at 15-100%.

[0019] In step (2), the liquid is placed in the tank for 0.5-5h.

[0020] In step (3), the salt alkali conversion agent X is one or two of calcium hydroxide, barium hydroxide and sodium hydroxide.

[0021] Further preferably, the molar ratio of the salt alkali converter X to the sum of carbonate and bicarbonate is 2-0.5:1.

[0022] Compared with the prior art, the present application realizes efficient impurity removal and recovery of aniline-nitrobenzene condensation reaction waste catalyst liquid containing high-concentration organic impurities, has good catalyst impurity removal effect and high recovery rate; the additives used in the treatment process are widely available and low in cost, a large amount of adsorbent is saved; the use of extraction solvents is effectively avoided, the amount of waste liquid and waste residue generated in the treatment process is small, it is green and environmentally friendly, and it is economical. DETAILED DESCRIPTION

[0023] In order to enable personnel in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below.

[0024] Example 1: A method for removing impurities and recovering aniline-nitrobenzene condensation reaction catalyst, a certain batch of waste catalyst liquid after being recycled in aniline-nitrobenzene condensation reaction is taken as a treatment object, the liquid is analyzed, the content of tetramethylammonium hydroxide is 14.2%, the content of carbonate is 1.2%, and the content of organic impurities is 5.8%. The method specifically comprises the following steps:

[0025] (1) 10 kg of the above-mentioned condensation reaction waste catalyst liquid is transported into a 20 L pressure-resistant reaction kettle, heated to 75℃, stirring is started, 50 g of resorcinol is added, after 1 h of reaction, 100 g of 30% formaldehyde solution is added, and the reaction continues at 75℃ for 1 h; after the reaction is completed, CO2 is introduced, the pressure is increased to 1 MPa, and the mixture is stirred for 0.5 h, then the pH of the liquid in the kettle is determined by on-line sampling, the pH is 7.1, and the CO2 in the kettle is recovered under reduced pressure;

[0026] (2) The liquid treated in step (1) is moved from the reaction kettle to a tank, the liquid is fully static in the tank for 2 h to allow the precipitated organic impurities to fully settle, the upper liquid after the impurities are separated by sedimentation is directly returned to the reaction kettle, and the lower impurities are filtered, and the filtrate is returned to the reaction kettle; the total amount of the liquid in the kettle is about 9.93 kg, and the content of carbonate is 4.7% and the content of bicarbonate is 2.48% in the liquid.

[0027] (3) 875 g of calcium hydroxide is added to the reaction kettle, heated to 75℃, and stirred to react, after 2 h of reaction, the temperature is reduced to 35℃, the material is removed from the reaction kettle, and filtered through a filter to obtain 9.6 kg of filtrate as recovered condensation catalyst, which is recorded as S1. The recovered condensation catalyst liquid S1 obtained by treatment is analyzed, the content of tetramethylammonium hydroxide is 18.6%, and the content of organic impurities is 0.08%.

[0028] Example 2: A method for removing impurities and recovering aniline-nitrobenzene condensation reaction catalyst, using the same batch of waste catalyst liquid as in Example 1 as the treatment object. The specific treatment method includes the following steps:

[0029] (1) Take 10 kg of the above-mentioned condensation reaction waste catalyst liquid and transfer it to a 20 L pressure-resistant reaction kettle, heat it to 70°C, start stirring, add 20 g of hydroquinone, react for 1.5 h, then add 25 g of glyoxal, continue to react at 70°C for 1.5 h; After the reaction is completed, CO2 is introduced, and the pressure is increased to 0.5 MPa to continue stirring and mixing for 0.5 h. Then, the pH of the liquid in the kettle is measured by on-line sampling, and the pH is 7.8. The pressure is reduced, and the CO2 in the kettle is recovered;

[0030] (2) The liquid treated in step (1) is transferred from the reaction kettle to a tank, and the liquid is allowed to stand in the tank for 2 h to allow the organic impurities to settle. The upper layer of the liquid after the impurities are separated is returned directly to the reaction kettle, and the lower layer of impurities is filtered, and the filtrate is returned to the reaction kettle. The total amount of the liquid in the kettle is about 9.75 kg, and the carbonate content of the liquid is 5.79%.

[0031] (3) Add 697 g of calcium hydroxide to the reaction kettle, heat it to 70°C, start stirring, and react for 2 h. Then, the temperature is reduced to 30°C, and the material is removed from the reaction kettle and sent to a filter for filtration, obtaining 9.48 kg of filtrate as recovered condensation catalyst, denoted as S2. The recovered condensation catalyst liquid S2 obtained by treatment is analyzed, and the tetramethylammonium hydroxide content is 18.8%, and the organic impurity content is 0.11%.

[0032] Example 3: A method for removing impurities and recovering aniline-nitrobenzene condensation reaction catalyst, using the same batch of waste catalyst liquid as in Example 1 as the treatment object. The specific treatment method includes the following steps:

[0033] (1) Take 10 kg of the above-mentioned condensation reaction waste catalyst liquid and transfer it to a 20 L pressure-resistant reaction kettle, heat it to 65°C, start stirring, add 25 g of hydroquinone and 25 g of catechol, react for 1.5 h, then add 30 g of propyl aldehyde, continue to react at 65°C for 1.5 h; After the reaction is completed, CO2 is introduced, and the pressure is increased to 0.3 MPa to continue stirring and mixing for 0.8 h. Then, the pH of the liquid in the kettle is measured by on-line sampling, and the pH is 7.6. The pressure is reduced, and the CO2 in the kettle is recovered;

[0034] (2) The liquid treated in step (1) is transferred from the reaction kettle to a tank, and the liquid is allowed to stand in the tank for 2.5 h to allow the organic impurities to settle. The upper layer of the liquid after the impurities are separated is returned directly to the reaction kettle, and the lower layer of impurities is filtered, and the filtrate is returned to the reaction kettle. The total amount of the liquid in the kettle is about 9.77 kg, and the carbonate content of the liquid is 5.93%.

[0035] (3) Put 1.656 kg of barium hydroxide into the reactor, and heat to 70°C. Start stirring and react for 2 hours. Then cool to 30°C, and remove the material from the reactor and filter it in a filter. The filtrate is 9.48 kg, which is the recovered condensation catalyst, and is noted as S3. The recovered condensation catalyst S3 is analyzed, and the tetramethylammonium hydroxide content is 18.5%, and the organic impurity content is 0.12%.

[0036] Example 4 (Comparative Example 1): The same batch of waste catalyst liquid as in Example 1 is used as the treatment object. The specific treatment method includes the following steps:

[0037] (1) Take 10 kg of the above-mentioned condensation reaction waste catalyst liquid and transfer it to a 20 L pressure-resistant reactor. Heat to 75°C, start stirring, and introduce CO2. Pressurize to 1 MPa, continue stirring and mixing for 0.5 h, then take an online sample of the material in the reactor to measure the pH. The pH is 7.3, and the CO2 in the reactor is recovered by decompression.

[0038] (2) After the treatment in step (1), the liquid is removed from the reactor to a tank, and the liquid is allowed to stand in the tank for 2 h to allow the organic impurities to settle. The upper layer of the liquid after the impurities are separated is returned directly to the reactor, and the lower layer of the impurities is filtered, and the filtrate is returned to the reactor. The total amount of the liquid in the reactor is about 9.99 kg, and the liquid is analyzed. The carbonate content is 4.85%, and the bicarbonate content is 2.07%.

[0039] (3) Put 850 g of calcium hydroxide into the reactor, and heat to 75°C. Start stirring and react for 2 hours. Then cool to 35°C, and remove the material from the reactor and filter it in a filter. The filtrate is 9.83 kg, which is the recovered condensation catalyst, and is noted as S4. The recovered condensation catalyst S4 is analyzed, and the tetramethylammonium hydroxide content is 14.3%, and the organic impurity content is 1.71%.

[0040] Example 5 (Comparative Example 2): The same batch of waste catalyst liquid as in Example 1 is used as the treatment object. The specific treatment method includes the following steps:

[0041] (1) Take 10 kg of the above-mentioned condensation reaction waste catalyst liquid and transfer it to a 20 L pressure-resistant reactor. Heat to 75°C, start stirring, and introduce CO2. Pressurize to 1 MPa, continue stirring and mixing for 0.5 h, then take an online sample of the material in the reactor to measure the pH. The pH is 7.3, and the CO2 in the reactor is recovered by decompression.

[0042] (2) The material liquid treated in step (1) is moved from the reactor to a tank, and the material liquid is fully rested in the tank for 2 hours to allow the precipitated organic impurities to fully settle. The upper layer of the material liquid after the impurities are separated by settling is directly returned to the reactor, and the lower layer of the impurities is filtered, and the filtrate is returned to the reactor. The total amount of the material liquid in the reactor is about 9.9 kg. The material liquid is analyzed, and the content of carbonate is 4.83%, and the content of bicarbonate is 2.22%.

[0043] (3) 860 g of calcium hydroxide is added to the reactor, and the temperature is raised to 75°C, and stirring is started for reaction. After 2 hours of reaction, the temperature is lowered to 35°C, and the material is moved out of the reactor and sent to a filter for filtration, and 9.68 kg of filtrate is obtained as the recovered condensation catalyst, which is denoted as S5. The recovered condensation catalyst material liquid S5 obtained by treatment is analyzed, and the content of tetramethylammonium hydroxide is 15.8%, and the content of organic impurities is 0.83%.

[0044] Example 6: Verification experiment of condensation reaction

[0045] The condensation reaction catalyst material liquid recovered by impurity removal treatment in Examples 1, 2, 3, 4, 5 is used for aniline-nitrobenzene condensation reaction respectively to verify its influence on the condensation reaction.

[0046] The specific condensation reaction operation is as follows: 1.2 kg of aniline, 0.2 kg of nitrobenzene, and a certain amount of recovered condensation catalyst material liquid are added to the condensation reactor, wherein the amount of the recovered condensation catalyst material liquid is metered and added according to the molar ratio of the content of tetramethylammonium hydroxide therein to 0.2 kg of nitrobenzene as 1.2:1. After nitrogen replacement, the reaction temperature is controlled at 70°C, the reaction pressure is-0.09 Mpa, and the dehydration condensation reaction is carried out, and the reaction time is controlled for 2 hours. After the reaction is completed, the material liquid is sampled and analyzed by high performance liquid chromatography, and the results are as follows.

[0047]

[0048] From the above analysis results, it can be seen that when the condensation catalyst recovered by Examples 1, 2, 3 is used, the raw material nitrobenzene can be completely converted, and the tar impurities generated in the reaction are less, which shows that using S1, S2, S3 as catalysts does not adversely affect the condensation reaction. As a comparison, when the recovered bases S4, S5 obtained by Examples 4, 5 are used as condensation reaction catalysts, the raw material nitrobenzene cannot be completely converted, and the tar impurities generated in the reaction increase significantly. Accordingly, it can be judged that the recovered condensation catalyst material liquid brings in too much organic impurities and a small amount of phenolic substances, which will have a more obvious adverse effect on the condensation reaction and will exacerbate the occurrence of side reactions.

[0049] Obviously, the above described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

Claims

1. A method for removing impurities and recovering waste catalyst from the aniline-nitrobenzene condensation reaction, using the waste catalyst liquid after recycling from the aniline-nitrobenzene condensation reaction as the treatment target, characterized in that, It comprises the following steps: (1) the waste catalyst liquid is transported to a pressure-resistant reaction kettle, and after being heated and stirred, a phenolic additive A is added for reaction, then an aldehyde additive B is added for further reaction, after the reaction, carbon dioxide is introduced, and the mixture is stirred under pressure, the salting rate of tetramethylammonium hydroxide is controlled at 15-100%, then the pressure is reduced, and the carbon dioxide is recovered; (2) the liquid treated in step (1) is moved from the reaction kettle to a tank for standing and precipitation, so that the precipitated organic impurities are fully settled, the upper liquid after the impurities are separated by settlement is directly returned to the reaction kettle, and the lower impurities are filtered, and the filtrate is returned to the reaction kettle; (3) a salt-alkali conversion agent X is added to the reaction kettle, and the mixture is heated and stirred for reaction, after the reaction, the mixture is cooled, moved out of the reaction kettle, and sent to a filter for filtration, and the obtained filtrate is sent to a concentration section and used as a recovered condensation catalyst for recycling; The salt-alkali conversion agent X is one or two of calcium hydroxide, barium hydroxide and sodium hydroxide.

2. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (1), the phenolic additive A is one or more of m-dihydroxybenzene, p-dihydroxybenzene and o-dihydroxybenzene, and the aldehyde additive B is one of formaldehyde, acetaldehyde, glyoxal and propyl aldehyde.

3. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (1), the mass ratio of the catalyst liquid, the phenolic additive A and the aldehyde additive B is 1:0.0001-0.005:0.0001-0.

005.

4. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (1), after the phenolic additive A and the aldehyde additive B are added, the reaction temperature of the liquid is 40-80℃, and the reaction time is 0.5-5h.

5. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (1), the pressure of the introduced carbon dioxide is 0.1-5MPa, and the stirring reaction time is 0.5-5h.

6. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (2), the standing time of the liquid in the tank is 0.5-5h.

7. The method of claim 1, wherein the aniline-nitrobenzene condensation reaction spent catalyst is recovered by removing impurities. In step (3), the molar ratio of the salt-alkali conversion agent X to the total of carbonate and bicarbonate is 2-0.5:1.

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