A method and apparatus for the thin film reaction preparation of RTM resol condensate

Abstract

This invention provides a method and apparatus for preparing RT-plast condensate using a thin-film reaction. The apparatus consists of a salt-forming filtration unit and a condensation reaction unit, which is further divided into a primary condensation step, a secondary condensation step, and a multi-stage condensation step. The method includes: dehydrating aniline, an organic base, and liquid alkali into salt in a thin-film reactor, filtering to obtain a desalted alkali solution, and then entering the condensation reaction step, where it is mixed with nitrobenzene and dehydrated and condensed to obtain the RT-plast condensate. Using a thin-film reaction apparatus for preparing the RT-plast condensate, the material residence time in the reaction apparatus is only 5-15 minutes, far shorter than the 3-5 hours of continuous batch condensation, significantly improving the efficiency of the condensation reaction.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals and relates to a method and apparatus for preparing RT plast condensate via thin-film reaction. Background Technology

[0002] RT-Pyrate, chemically known as p-aminodiphenylamine, can be used in rubber additives, dyes, textiles, printing and pharmaceutical industries, etc. It is mainly used to produce p-phenylenediamine rubber antioxidants such as 6PPD and 4010NA. The global production capacity of RT-Pyrate is approximately 225kt / a.

[0003] The nitrobenzene process is currently the most widely used process for synthesizing p-aminodiphenylamine internationally, and it is a clean and green process. In the nitrobenzene process for producing RT (p-aminodiphenylamine), the condensation step uses a batch reactor. Aniline, nitrobenzene, and the catalyst quaternary ammonium base react under vacuum conditions to yield 4-nitrodiphenylamine and 4-nitrosodiphenylamine. The reaction process is as follows:

[0004] (1) Aniline reacts with an organic base to dehydrate and generate aniline anions.

[0005]

[0006] The dehydration of aniline with organic bases to produce aniline anions is a prerequisite for the condensation of aniline with nitrobenzene to produce 4-(nitroso)nitrate.

[0007] (2) The aniline anion reacts with nitrobenzene to form a complex.

[0008]

[0009] The formation of the complex is key to the overall selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine.

[0010] (3) Rearrangement, hydrolysis

[0011]

[0012] The complex undergoes molecular rearrangement and hydrolysis to yield 4-nitrosodiphenylamine, or reacts with nitrobenzene followed by rearrangement and hydrolysis to yield 4-nitrosodiphenylamine. During rearrangement, one molecule of water is released, and during hydrolysis, one molecule of water is consumed, releasing tetramethylammonium hydroxide. From step (1) to step (3), tetramethylammonium hydroxide completes the catalytic condensation process.

[0013] (4) 4-(nitrosodiphenylamine) is hydrogenated and reduced to RT-pes, and azobenzene is reduced to aniline.

[0014]

[0015] Currently, in the production of RT-based nitrobenzene, the preparation of the condensation solution mainly adopts a continuous batch process. As the reaction proceeds, a large amount of material circulates and undergoes dehydration and condensation reactions within the reactor, resulting in a high material backmixing rate and long residence time, which seriously affects production efficiency. Summary of the Invention

[0016] To address the problems of high material backmixing rate, long residence time, and low production efficiency in existing RT paste condensate preparation processes, this invention provides a method and apparatus for preparing RT paste condensate via thin-film reaction.

[0017] The technical solution adopted in this invention is:

[0018] A method for preparing RT-based condensate via thin-film reaction includes the following steps:

[0019] (1) Aniline, organic base and liquid alkali are mixed in proportion and then fed into the first membrane reactor for dehydration and salt formation. The salt-formed material is then filtered to remove carbonate ions from the material.

[0020] (2) After the desalted material is mixed with nitrobenzene, it enters the second membrane reactor for dehydration and condensation to generate 4-nitrodiphenylamine and 4-nitrosodiphenylamine, namely RT condensate.

[0021] Further, in step (1), the organic base is an aqueous solution of tetramethylammonium hydroxide with a mass content of 10-35%, and the molar ratio of tetramethylammonium hydroxide to aniline is 1:3-7.

[0022] Further, in step (1), the liquid alkali is an aqueous solution of sodium hydroxide with a mass content of 10-35%, and the molar ratio of sodium hydroxide to carbonate ions in the organic alkali is 0-2:1.

[0023] Furthermore, in step (2), the molar ratio of nitrobenzene to tetramethylammonium hydroxide in the desalted material is 0.8 to 1.2:1.

[0024] Furthermore, in step (1), the temperature for dehydration and salt formation is 60-70°C, and the vacuum degree is 0.080-0.099 MPa.

[0025] Furthermore, in step (2), the dehydration condensation reaction temperature is 65–85 °C and the vacuum degree is 0.080–0.099 MPa.

[0026] An apparatus for preparing RT-plast condensate via thin-film reaction using any of the methods described above, comprising a salt-forming filtration unit and a condensation reaction unit.

[0027] The salt-forming filtration unit includes a mixing vessel #1, a membrane reactor #1, filter A, filter B, a desalination alkali intermediate tank, and a desalination alkali metering pump. The outlet of the mixing vessel #1 is connected to the inlet of the membrane reactor #1. The outlet of the membrane reactor #1 is connected to the inlets of filter A and filter B through pipes and valves. The filtrate outlets of filter A and filter B are connected to the inlet of the desalination alkali intermediate tank. The desalination alkali metering pump is used to transport the desalination alkali in the desalination alkali intermediate tank to the condensation reaction unit.

[0028] The condensation reaction unit includes at least one condensation reaction device. The single-stage condensation reaction device includes a No. 2 mixing vessel, a No. 2 thin-film reactor, and a condensation liquid tank. The inlet of the No. 2 mixing vessel is connected to the outlet of the desalination metering pump, the outlet of the No. 2 mixing vessel is connected to the inlet of the No. 2 thin-film reactor, and the outlet of the No. 2 thin-film reactor is connected to the inlet of the condensation liquid tank.

[0029] Furthermore, the condensation reaction unit includes a two-stage condensation reaction device connected in series.

[0030] Furthermore, both the No. 1 and No. 2 membrane reactors are scraped-film falling film reactors.

[0031] Furthermore, the apparatus for preparing RT plast condensate via thin-film reaction also includes a storage unit. The storage unit includes a nitrobenzene tank, a nitrobenzene metering pump, an aniline tank, an aniline metering pump, a liquid alkali tank, a liquid alkali metering pump, an organic alkali tank, an organic alkali metering pump, and an aniline water tank. The aniline tank, liquid alkali tank, and organic alkali tank are respectively connected to the inlet of mixing vessel #1 via the aniline metering pump, liquid alkali metering pump, and organic alkali metering pump. The nitrobenzene tank is connected to the inlet of mixing vessel #2 via the nitrobenzene metering pump. The aniline water tank is used to collect the condensate from each thin-film reactor.

[0032] The beneficial effects of this invention are: by using a thin-film reactor for dehydration, desalination, and dehydration condensation to prepare RT condensate, the condensation reaction time can be reduced from 3-5 hours in the traditional batch reactor to 3-15 minutes (including the residence time of materials in the pipeline and mixing vessel), which greatly improves the efficiency of the condensation reaction. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of Embodiments 1-2 of the present invention.

[0034] Figure 2 This is a process flow diagram of embodiments 3-4 of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the embodiments.

[0036] Example 1

[0037] See Figure 1 This embodiment provides an apparatus for preparing RT-based condensate via thin-film reaction, comprising a storage unit, a salt-forming filtration unit, and a condensation reaction unit;

[0038] The salt-forming filtration unit includes a mixing vessel 21, a membrane reactor 22, a filter A 23, a filter B 24, a desalination intermediate tank 25, and a desalination metering pump 26. The outlet of the mixing vessel 21 is connected to the inlet of the membrane reactor 22. The outlet of the membrane reactor 22 is connected to the inlets of the filters A 23 and B 24 through pipes and valves. The filtrate outlets of the filters A 23 and B 24 are connected to the inlet of the desalination intermediate tank 25. The outlet of the desalination intermediate tank 25 is connected to the inlet of the desalination metering pump 26.

[0039] The condensation reaction unit includes two stages of condensation reaction devices connected in series. The first-stage condensation unit includes a No. 2 mixing vessel 31, a No. 2 thin-film reactor 32, a first-stage condensation intermediate tank 33, and a first-stage condensation liquid metering pump 34. The second-stage condensation unit includes a No. 3 mixing vessel 41, a No. 3 thin-film reactor 42, and a condensation liquid tank 45. The inlet of the No. 2 mixing vessel 31 is connected to the outlet of the desalination metering pump 26, the outlet of the No. 2 mixing vessel 31 is connected to the inlet of the No. 2 thin-film reactor 32, the outlet of the No. 2 thin-film reactor 32 is connected to the inlet of the first-stage condensation intermediate tank 33, the outlet of the first-stage condensation intermediate tank 33 is connected to the inlet of the first-stage condensation liquid metering pump 34, the outlet of the first-stage condensation liquid metering pump 34 is connected to the inlet of the No. 3 mixing vessel 41, the outlet of the No. 3 mixing vessel 41 is connected to the inlet of the No. 3 thin-film reactor 42, and the outlet of the No. 3 thin-film reactor 42 is connected to the inlet of the condensation liquid tank 45.

[0040] Thin film reactors 22 (1#), 32 (2#), and 42 (31#) are all scraped-plate falling film reactors. Each thin film reactor is equipped with a separate condenser and vacuum system, and the condenser is connected to the vacuum system. The condensate in condenser 27 (1#) is pumped into aniline water tank 15 by condensate pump 28 (1#), the condensate in condenser 35 (2#) is pumped into aniline water tank 15 by condensate pump 36 (2#), and the condensate in condenser 43 (3#) is pumped into aniline water tank 15 by condensate pump 44 (3#).

[0041] The storage unit includes a nitrobenzene tank 11, a nitrobenzene metering pump 111, an aniline tank 12, an aniline metering pump 121, a liquid alkali tank 13, a liquid alkali metering pump 131, an organic alkali tank 14, an organic alkali metering pump 141, and an aniline water tank 15. The aniline tank 12, the liquid alkali tank 13, and the organic alkali tank 14 are connected to the inlet of mixing vessel 21 (No. 1) through the aniline metering pump 121, the liquid alkali metering pump 131, and the organic alkali metering pump 141, respectively. The nitrobenzene tank 11 is connected to the inlet of mixing vessel 31 (No. 2) through the nitrobenzene metering pump 111.

[0042] The RT-plast condensate is prepared using the above-described apparatus, and the specific method includes:

[0043] (1) 150 parts by weight of aniline stored in aniline tank 12, 150 parts by weight of organic alkali (containing 20% ​​tetramethylammonium hydroxide and 2.1% carbonate ions) stored in organic alkali tank 14, and 10 parts by weight of sodium hydroxide aqueous solution (containing 30% sodium hydroxide) stored in liquid alkali tank 13 are added to mixing vessel 21 through metering pumps. After stirring evenly, the mixture is introduced into thin film reactor 22. The temperature inside thin film evaporator is controlled at 65℃ and the vacuum degree is 0.090MPa. As the scraper in the thin film reactor rotates, the material is evenly coated on the inner wall of the thin film reactor to form salt. The salted material enters filter A23 for filtration, and the filtrate enters desalination intermediate tank 25. When the amount of carbonate residue in the filter reaches a certain value, the filter is switched, and the salted material enters filter B24. The salt residue in filter A is taken out and treated as waste residue. The filter switching is repeated to obtain the filtered liquid phase, i.e., 225 parts of desalinated alkali solution.

[0044] Analysis of the alkaline solution after desalination: tetramethylammonium hydroxide 17.04%, carbonate ion content 0.42%, sodium ion residue 0.011%.

[0045] (3) 100 parts by weight of the desalted alkaline solution temporarily stored in the desalting alkaline intermediate tank 25 and 20 parts by weight of nitrobenzene stored in the nitrobenzene tank 11 were added to the No. 2 mixing vessel 31 by metering pumps. After being stirred evenly, the mixture was introduced into the No. 2 thin film reactor 32. The reaction temperature of the No. 2 thin film reactor was controlled at 75°C and the vacuum degree was 0.097MPa. After the material stayed in the No. 2 thin film reactor for 10s, it was introduced into the first-stage condensation intermediate tank 33. Then, it was pumped into the No. 3 mixing vessel 41 by the first-stage condensation liquid metering pump 34. After being stirred evenly, the mixture was introduced into the No. 3 thin film reactor 42. The reaction temperature of the No. 3 thin film reactor was controlled at 75°C and the vacuum degree was 0.097MPa. After the material stayed in the No. 3 thin film reactor for 10s, it was introduced into the condensation liquid tank 45 to obtain 105 parts of RT pyrite condensation liquid.

[0046] Analysis of the composition of the condensation liquid revealed that nitrobenzene accounted for 0.35%, 4-nitrosodiphenylamine for 27.51%, and 4-nitrodiphenylamine for 3.12%.

[0047] Example 2

[0048] The process flow is the same as in Example 1, except that:

[0049] 150 parts by weight of aniline, 200 parts by weight of organic base (containing 25% tetramethylammonium hydroxide and 0.5% carbonate ions), and 2 parts by weight of sodium hydroxide aqueous solution (containing 30% sodium hydroxide) were added to mixing vessel 21 (No. 1) using a metering pump. The temperature inside the thin-film evaporator (No. 1) was controlled at 60°C and the vacuum degree at 0.098 MPa to carry out dehydration and desalination, yielding 250 parts of desalted alkaline solution.

[0050] Analysis of the alkaline solution after desalination: tetramethylammonium hydroxide 20.70%, carbonate ion content 0.24%, sodium ion residue 0.008%;

[0051] 100 parts by weight of the desalted alkaline solution and 30 parts by weight of nitrobenzene were added to a two-stage series of thin-film reactors. The reaction temperature of each thin-film reactor was controlled at 75°C, the vacuum degree was 0.097 MPa, and the residence time of the material in a single thin-film reactor was 10 s, resulting in 105 parts of RT pyrolysis condensate.

[0052] The composition of the condensation solution is as follows: nitrobenzene balance 0.35%, 4-nitrosodiphenylamine 27.51% and 4-nitrodiphenylamine 3.12%.

[0053] Example 3

[0054] See Figure 2 The apparatus for preparing RT condensate condensate by thin film reaction in Example 3 is basically the same as that in Example 1, except that the condensation reaction unit includes a primary condensation reaction device, namely, a mixing vessel 31, a thin film reactor 32, and a condensate tank 45. The outlet of the thin film reactor 32 is connected to the inlet of the condensate tank 45.

[0055] The RT-plast condensate was prepared using the above apparatus, and the method was basically the same as in Example 1, except that:

[0056] 150 parts by weight of aniline, 120 parts by weight of organic base (containing 25% tetramethylammonium hydroxide and 1.5% carbonate ions), and 9 parts by weight of sodium hydroxide aqueous solution (containing 20% ​​sodium hydroxide) were added to mixing vessel No. 1. The temperature inside the thin film evaporator No. 1 was controlled at 70°C and the vacuum degree was 0.085 MPa to carry out dehydration and desalination, and 195 parts of desalted alkaline solution were obtained.

[0057] Analysis of the alkaline solution after desalination: tetramethylammonium hydroxide 17.98%, carbonate ion content 0.28%, sodium ion residue 0.008%.

[0058] 100 parts by weight of the desalted alkaline solution and 20 parts by weight of nitrobenzene were added to mixing vessel 2# 31. The reaction temperature of membrane reactor 2# 32 was controlled at 80℃ and the vacuum degree was 0.092MPa. The material was placed in the membrane reactor for 15s and then entered the condensation tank 45 to obtain 103 parts of RT basalt condensation solution.

[0059] The composition of the condensation solution is as follows: nitrobenzene balance 0.28%, 4-nitrosodiphenylamine 28.67% and 4-nitrodiphenylamine 3.67%.

[0060] Example 4

[0061] The process flow is the same as in Example 3, except that:

[0062] 150 parts by weight of aniline and 120 parts by weight of organic base (containing 25% tetramethylammonium hydroxide and 1.5% carbonate ions) were added to mixing vessel No. 1. The temperature inside the membrane reactor No. 1 was controlled at 65℃ and the vacuum degree was 0.090MPa, resulting in 205 parts of alkaline solution after passing through the membrane reactor.

[0063] Analysis of the alkaline solution: tetramethylammonium hydroxide 14.12%, carbonate ion content 0.93%.

[0064] 100 parts by weight of the dehydrated and concentrated alkali solution and 20 parts by weight of nitrobenzene were added to mixing vessel No. 2 via a metering pump. The reaction temperature in the No. 2 thin film reactor was controlled at 80℃, the vacuum degree at 0.092MPa, and the residence time of the material in the thin film reactor was 15s, resulting in 103 parts of RT pyrite condensate.

[0065] Analysis of the composition of the condensation solution revealed that nitrobenzene accounted for 0.48%, 4-nitrosodiphenylamine for 27.63%, and 4-nitrodiphenylamine for 3.79%.

Claims

1. A method for the production of a RTM® PES condensate solution by thin film reaction, characterized in that Includes the following steps: (1) Aniline, organic base and liquid alkali are mixed in proportion and then fed into the first membrane reactor for dehydration and salt formation. The salt-formed material is then filtered to remove carbonate ions from the material. (2) After the desalted material is mixed with nitrobenzene, it enters the second membrane reactor for dehydration and condensation to generate 4-nitrodiphenylamine and 4-nitrosodiphenylamine, namely RT condensate.

2. The method of claim 1, wherein the RTU condensate is prepared by a thin film reaction. In step (1), the organic base is an aqueous solution of tetramethylammonium hydroxide with a mass content of 10-35%, and the molar ratio of tetramethylammonium hydroxide to aniline is 1:3-7.

3. The method of claim 1, wherein the RTV silicone condensation liquid is prepared by a thin film reaction, and the thin film reaction is performed by using a thin film reactor. In step (1), the liquid alkali is an aqueous solution of sodium hydroxide with a mass content of 10-35%, and the molar ratio of sodium hydroxide to carbonate ions in the organic alkali is 0-2:

1.

4. The method of claim 1, wherein the RTV silicone condensation liquid is prepared by a thin film reaction, and In step (2), the molar ratio of nitrobenzene to tetramethylammonium hydroxide in the desalted material is 0.8 to 1.2:

1.

5. The method of claim 1, wherein the RTV silicone condensation liquid is prepared by a thin film reaction, and the thin film reaction is performed by using a thin film reactor. In step (1), the temperature for dehydration and salt formation is 60-70℃ and the vacuum degree is 0.080-0.099MPa.

6. The method for preparing RT-Plast condensate via thin-film reaction according to claim 1, characterized in that, In step (2), the dehydration condensation reaction temperature is 65-85℃ and the vacuum degree is 0.080-0.099MPa.

7. An apparatus for preparing RT-plast condensate via thin-film reaction using the method according to any one of claims 1 to 6, characterized in that, Includes a salt formation and filtration unit and a condensation reaction unit. The salt-forming filtration unit includes a mixing vessel (21), a membrane reactor (22), a filter A (23), a filter B (24), a desalination alkali intermediate tank (25), and a desalination alkali metering pump (26). The outlet of the mixing vessel (21) is connected to the inlet of the membrane reactor (22). The outlet of the membrane reactor (22) is connected to the inlets of the filters A (23) and B (24) through pipes and valves. The filtrate outlets of the filters A (23) and B (24) are connected to the inlet of the desalination alkali intermediate tank (25). The desalination alkali metering pump (26) is used to transport the desalination alkali in the desalination alkali intermediate tank (25) to the condensation reaction unit. The condensation reaction unit includes at least one condensation reaction device. The single-stage condensation reaction device includes a No. 2 mixing vessel (31), a No. 2 thin film reactor (32), and a condensation liquid tank (45). The inlet of the No. 2 mixing vessel (31) is connected to the outlet of the desalination metering pump (26), the outlet of the No. 2 mixing vessel (31) is connected to the inlet of the No. 2 thin film reactor (32), and the outlet of the No. 2 thin film reactor (32) is connected to the inlet of the condensation liquid tank (45).

8. The apparatus for preparing RT-plast condensate by thin-film reaction according to claim 7, characterized in that, The condensation reaction unit includes a two-stage condensation reaction device connected in series.

9. The apparatus for preparing RT-Plast condensate via thin-film reaction according to claim 7, characterized in that, Both the No. 1 membrane reactor (22) and the No. 2 membrane reactor (32) are scraped falling film reactors.

10. The apparatus for preparing RT-plast condensate via thin-film reaction according to claim 7, characterized in that, It also includes a storage unit, which includes a nitrobenzene tank (11), a nitrobenzene metering pump (111), an aniline tank (12), an aniline metering pump (121), a liquid alkali tank (13), a liquid alkali metering pump (131), an organic alkali tank (14), an organic alkali metering pump (141), and an aniline water tank (15). The aniline tank (12), the liquid alkali tank (13), and the organic alkali tank (14) are connected to the inlet of mixing vessel 1 (21) through the aniline metering pump (121), the liquid alkali metering pump (131), and the organic alkali metering pump (141), respectively. The nitrobenzene tank (11) is connected to the inlet of mixing vessel 2 (31) through the nitrobenzene metering pump (111). The aniline water tank (15) is used to collect the condensate from each thin film reactor.

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