Industrial method for continuous and efficient catalytic synthesis of m-nitroaniline

Abstract

The invention relates to an industrial method for continuous high-efficiency catalytic synthesis of m-nitroaniline, which comprises the following steps: preparing a m-nitrochlorobenzene solution, fully mixing the m-nitrochlorobenzene solution and a concentrated ammonia water solution in a mixer, preheating in a preheater after mixing, passing through a fixed bed dynamic tubular reactor, and carrying out continuous high-efficiency catalytic synthesis of m-nitroaniline. Reacting in a dynamic tubular reactor under the catalysis of a fixed bed catalyst, cooling in a cooling kettle for gas-liquid separation, and elutriating and filtering in an elutriating kettle to obtain a final product. The process safety risk can be remarkably reduced, the reaction period is greatly shortened, the process operation is simple and convenient to regulate and control, and the process stability is high.

Description

Technical Field

[0001] The invention relates to the field of fine chemicals, and in particular to an industrial method for continuously and efficiently catalytically synthesizing m-nitroaniline. Background Art

[0002] Meta-nitroaniline is an important fine chemical, mainly used as a pharmaceutical intermediate and dye intermediate. It is used to test the color of pine wood in organic synthesis, and can also be used as an acid-base indicator, pH 6.8 (colorless)-8.6 (yellow). It can be used as an orange base R for ice dye and to prepare color phenol AS-BS. Meta-nitroaniline can be hydroxyethylated with ethylene oxide to obtain 3-nitro-N, N-diethanolaniline.

[0003] There are two main methods for preparing m-nitroaniline: the m-dinitrobenzene reduction method and the m-nitrochlorobenzene ammonolysis method.

[0004] The raw material of the m-dinitrobenzene reduction process is m-dinitrobenzene. The reducing agents used in the early preparation of m-nitroaniline were mainly alkali sulfide, iron powder, hydrazine hydrate, etc. However, these reduction processes will produce a large amount of wastewater that is difficult to treat, which is not conducive to clean production. With the continuous development of catalytic reduction technology, more and more catalytic reduction technologies are gradually used for the catalytic reduction of nitro compounds. The process of preparing m-nitroaniline by hydrogenation reduction of m-dinitrobenzene using skeleton nickel, skeleton ruthenium, etc. as catalysts is used, but the reaction endpoint is difficult to control, and it is easy to over-reduction to produce m-phenylenediamine. In the process of nitration of nitrobenzene, o-dinitrobenzene and p-dinitrobenzene will be produced as by-products, and they are difficult to purify. Therefore, the quality of m-nitroaniline obtained by this method is often not high.

[0005] The m-nitrochlorobenzene ammonolysis process uses m-nitrochlorobenzene as raw material and undergoes ammonolysis under high pressure to directly prepare m-nitroaniline. This process has high selectivity and can prepare high-purity m-nitroaniline. The traditional kettle ammonolysis process requires very high pressure, consumes a large amount of ammonia water, and produces a large amount of chlorine-containing wastewater, which is not environmentally friendly. Summary of the invention

[0006] In order to overcome the problems of high safety risk, low process efficiency, poor process stability and excessive consumption of ammonia water in the current traditional synthesis process of m-nitroaniline, the present invention is based on dynamic tubular reactor technology and uses a high-boiling point organic nitrogen heterocyclic water-soluble solvent (including but not limited to pyrazole, quinoline, N-methylpyrrolidone, etc.) as a solvent to provide a method for continuous and efficient catalytic synthesis of m-nitroaniline, which can not only significantly reduce the process safety risk and greatly shorten the reaction cycle, but also has simple process operation, easy control, strong process stability, and can effectively solve the problems raised in the background technology.

[0007] The invention provides a method for continuously synthesizing m-nitroaniline, comprising the following steps: fully mixing m-nitrochlorobenzene solution and concentrated ammonia solution in a mixer, preheating in a preheater, reacting in a dynamic tubular reactor through a fixed bed catalyst, cooling in a cooling kettle for gas-liquid separation, and filtering by water separation in a water separation kettle.

[0008] The specific steps include:

[0009] S1. Prepare a certain concentration of m-nitrochlorobenzene solution and a certain concentration of ammonia solution using water as solvent for later use.

[0010] S2, the m-nitrochlorobenzene solution and the ammonia solution are transported to a mixer in a certain ratio by a metering pump and fully mixed. The mixed liquid is sent to a preheater and heated to a certain temperature by steam feeding liquid.

[0011] S3, the preheated feed liquid is transported to a fixed bed dynamic tubular reactor, in which a silicon oxide nano-scale porous silicon oxide catalyst is placed. A screw propeller is provided in the dynamic tubular reactor. The jacket of the dynamic tubular reactor is passed through with heat transfer oil to heat the feed liquid. The feed liquid enters the reactor from the bottom of the reactor, reacts fully in the reactor, and enters the cooler after the reaction is completed.

[0012] S4, the feed liquid enters the cooler for cooling, and the cooled feed liquid enters the cooling kettle for gas-liquid separation, the gas enters the ammonia recovery system, the liquid overflows the kettle and enters the water separation kettle A / B, water is added to the water separation kettle, the final product is precipitated and filtered to recover the solvent.

[0013] According to claim S1, the solvent used is a high-boiling point organic nitrogen heterocyclic water-soluble solvent (including but not limited to pyrazole, quinoline, N-methylpyrrolidone, etc.), and the catalyst used is a quaternary ammonium salt phase transfer catalyst (including but not limited to tetrabutylammonium chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, etc.), and the mass ratio thereof is: m-nitrochlorobenzene: solvent: catalyst = 1:2.0-4.0:0.001-0.01.

[0014] According to claim S1, the concentration of the concentrated ammonia water used is 40-60wt%.

[0015] According to claim S2, the molar ratio of concentrated ammonia water to m-nitrochlorobenzene chlorine solution entering the mixer is: m-nitrochlorobenzene: ammonia = 1:8.0-12.0.

[0016] According to claim S2, the heat exchanger outlet temperature is controlled between 110-120°C.

[0017] According to claim S3, the reaction temperature of the mixed liquid in the fixed bed dynamic tubular reactor is between 190-200°C, and the reaction pressure in the fixed bed dynamic tubular reactor is between 11.0-13.5 MPa.

[0018] According to claim S3, the catalyst in the fixed bed is a nano-scale porous silica molecular sieve loaded with a metal catalyst (the loaded catalyst includes but is not limited to cupric chloride, cuprous chloride, aluminum chloride, copper oxide, chromium oxide, etc.).

[0019] According to claim S3, a stirring and dispersing device is provided in the fixed bed dynamic tubular reactor, and its form includes but is not limited to a screw propulsion type, a self-priming stirring type, etc.

[0020] According to claim S3, the residence time of the mixed liquid in the fixed bed dynamic tubular reactor is controlled at 45-80 min.

[0021] According to claim S4, after the reaction is completed, the feed liquid enters the cooler for cooling, and the chilled brine is passed through the cooler. The outlet temperature of the cooler is controlled below 120°C. After being cooled by the cooler, the feed liquid enters the cooling kettle through the submerged pipe. The jacket of the cooling kettle is passed with circulating water, and the temperature in the cooling kettle is controlled between 80-90°C.

[0022] According to claim S4, the gas phase on the cooling kettle is removed to the ammonia recovery system through a pressure relief valve. The liquid phase overflows into the water separation kettle A / B. A certain amount of water is first added to the water separation kettle, stirring is turned on, and the overflowing liquid enters the water and is fully stirred and then sent to the filter for filtration to obtain the product. The filtrate is sent to the distillation tower to recover the solvent.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts the preparation of m-nitrochlorobenzene solution and ammonia solution under the dual catalysis of phase transfer catalyst and reaction catalyst, and continuously performs high-temperature ammonolysis in a fixed bed dynamic tubular reactor to prepare m-nitroaniline. Compared with the prior art, the reaction time is greatly shortened from dozens of hours in an intermittent autoclave to less than one hour, the ammonia equivalent is controlled within 10, and the liquid holding capacity of the reaction system is greatly reduced. Compared with the microchannel reactor, the output of the reactor can be greatly increased, and industrial production can be realized. The process efficiency of the present invention is significantly improved, the safety of the reaction process is effectively enhanced, the continuous operation is simple and the process is controllable, and the process is more green and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0025] Among them, 1. m-nitrochlorobenzene dissolving kettle; 2. m-nitrochlorobenzene buffer tank; 3. concentrated ammonia water storage tank; 4. mixer; 5. preheater; 6. fixed bed dynamic tubular reactor; 7. fixed bed; 8. cooler; 9. cooling kettle; 10A / 10B, water separation kettle. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0027] Example 1

[0028] like Figure 1 As shown, an industrial method for continuously and efficiently catalytically synthesizing m-nitroaniline comprises the following steps: m-nitrochlorobenzene, pyridine and tetrabutylammonium chloride are added to a m-nitrochlorobenzene dissolving kettle 1 in a mass ratio of 1:2:0.001, and stirred and dissolved. The dissolved feed liquid is added to a m-nitrochlorobenzene buffer tank 2. The m-nitrochlorobenzene solution in the m-nitrochlorobenzene buffer tank 2 and the 48% concentrated ammonia water in the ammonia solution tank 3 are added to a mixer 4 in a molar ratio of 1:8, and then fully mixed and sent to a preheater 5, and the feed liquid is heated to 110°C by the preheater. The preheated feed liquid enters a fixed bed dynamic tubular reactor 6, and the feed liquid flows in from the bottom of the reactor at a certain flow rate, passes through a multi-stage fixed bed catalyst 7 for catalytic reaction, and then flows out from the top of the reactor. The catalyst in the multi-stage fixed bed catalyst 7 is a nano-porous silicon oxide molecular sieve loaded with copper oxide. The temperature in the reactor is controlled at about 190°C, at which time the pressure in the reactor is about 11MPa, and the feed liquid stays in the reactor for 50 minutes. The feed liquid flowing out of the reactor 6 enters the cooler 8 and cools down to about 115°C. The cooled feed liquid enters the cooling kettle 9 to continue cooling and gas-liquid separation. The temperature in the kettle is cooled to about 90°C, and the gas phase passes through the pressure relief valve to the tail gas absorption system. The feed liquid enters the water separation kettle 10A / B for water separation. Water with a total volume of 1 / 3 of the water separation kettle is added to the water separation kettle 10A / B in advance, and stirring is turned on. The feed liquid is added to the water and stirred fully. After the feed liquid accumulates to a certain amount, it is switched to another water separation kettle. Water separation kettles A / B are switched for use. After the water separation is completed, the feed liquid is filtered and washed to obtain the final product. After the final product is treated, the purity of the sample intermediate nitroaniline is 94.6% by high performance liquid chromatography analysis.

[0029] Example 2

[0030] like Figure 1As shown, an industrial method for continuously and efficiently catalytically synthesizing m-nitroaniline comprises the following steps: m-nitrochlorobenzene, pyridine and tetrabutylammonium chloride are added to a m-nitrochlorobenzene dissolving kettle 1 in a mass ratio of 1:3:0.001, and stirred and dissolved. The dissolved feed liquid is added to a m-nitrochlorobenzene buffer tank 2. The m-nitrochlorobenzene solution in the m-nitrochlorobenzene buffer tank 2 and the 48% concentrated ammonia water in the ammonia solution tank 3 are added to a mixer 4 in a molar ratio of 1:10, and then fully mixed and sent to a preheater 5, and the feed liquid is heated to 110°C by the preheater. The preheated feed liquid enters a fixed bed dynamic tubular reactor 6, and the feed liquid flows in from the bottom of the reactor at a certain flow rate, catalyzes the reaction through a multi-stage fixed bed catalyst 7, and then flows out from the top of the reactor. The catalyst in the multi-stage fixed bed catalyst 7 is a nano-porous silicon oxide molecular sieve loaded with copper oxide. The temperature in the reactor is controlled at about 195°C, at which time the pressure in the reactor is about 11.5MPa, and the feed liquid stays in the reactor for 1h. The feed liquid flowing out of the reactor 6 enters the cooler 8 and cools down to about 115°C. The cooled feed liquid enters the cooling kettle 9 to continue cooling and gas-liquid separation. The temperature in the kettle is cooled to about 90°C, and the gas phase passes through the pressure relief valve to the tail gas absorption system. The feed liquid enters the water separation kettle 10A / B for water separation. Water with a total volume of 1 / 3 of the water separation kettle is added to the water separation kettle 10A / B in advance, and stirring is turned on. The feed liquid is added to the water and stirred fully. After the feed liquid accumulates to a certain amount, it is switched to another water separation kettle. Water separation kettles A / B are switched for use. After the water separation is completed, the feed liquid is filtered and washed to obtain the final product. After the final product is treated, the purity of the sample intermediate nitroaniline is 98.6% by high performance liquid chromatography analysis.

[0031] Example 3

[0032] like Figure 1As shown, an industrial method for continuously and efficiently catalytically synthesizing m-nitroaniline comprises the following steps: m-nitrochlorobenzene, N-methylpyrrolidone and tetrabutylammonium chloride are added to a m-nitrochlorobenzene dissolving kettle 1 in a mass ratio of 1:2:0.001, and stirred and dissolved. The dissolved feed liquid is added to a m-nitrochlorobenzene buffer tank 2. The m-nitrochlorobenzene solution in the m-nitrochlorobenzene buffer tank 2 and the 60% concentrated ammonia water in the ammonia solution tank 3 are added to a mixer 4 in a molar ratio of 1:12, and then fully mixed and sent to a preheater 5, and the feed liquid is heated to 110°C by the preheater. The preheated feed liquid enters a fixed bed dynamic tubular reactor 6, and the feed liquid flows in from the bottom of the reactor at a certain flow rate, undergoes a catalytic reaction through a multi-stage fixed bed catalyst 7, and then flows out from the top of the reactor. The catalyst in the multi-stage fixed bed catalyst 7 is a nano-porous silicon oxide molecular sieve loaded with chromium trioxide. The temperature in the reactor is controlled at about 200°C, at which time the pressure in the reactor is about 12.5MPa, and the feed liquid stays in the reactor for 1h. The feed liquid flowing out of the reactor 6 enters the cooler 8 to cool down to about 115°C, and the cooled feed liquid enters the cooling kettle 9 to continue cooling and gas-liquid separation, and the temperature in the kettle is cooled to about 90°C, and the gas phase passes through the pressure relief valve to the tail gas absorption system. The feed liquid enters the water separation kettle 10A / B for water separation. Water with a total volume of 1 / 3 of the water separation kettle is added to the water separation kettle 10A / B in advance, and stirring is turned on. The feed liquid is added to the water and stirred fully. After the feed liquid accumulates to a certain amount, it is switched to another water separation kettle. Water separation kettles A / B are switched for use. After the water separation is completed, the feed liquid is filtered and washed to obtain the final product. After the final product is treated, the purity of the sample intermediate nitroaniline is 99.4% by high performance liquid chromatography analysis.

[0033] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements on parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made by those skilled in the art without creative labor on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. The present invention provides a method for continuously synthesizing m-nitroaniline, comprising the following steps: fully mixing m-nitrochlorobenzene solution and concentrated ammonia solution in a mixer, preheating in a preheater, reacting in a dynamic tubular reactor through a fixed bed catalyst, cooling in a cooling kettle for gas-liquid separation, and filtering by water separation in a water separation kettle. The specific steps include: S1. Prepare a certain concentration of m-nitrochlorobenzene solution and a certain concentration of ammonia solution using water as solvent for later use. S2, the m-nitrochlorobenzene solution and the ammonia solution are transported to a mixer in a certain ratio by a metering pump and fully mixed. The mixed liquid is sent to a preheater and heated to a certain temperature by steam feeding liquid. S3, the preheated feed liquid is transported to a fixed bed dynamic tubular reactor, in which a silicon oxide nano-scale porous silicon oxide catalyst is placed. A screw propeller is provided in the dynamic tubular reactor. The jacket of the dynamic tubular reactor is passed through with heat transfer oil to heat the feed liquid. The feed liquid enters the reactor from the bottom of the reactor, reacts fully in the reactor, and enters the cooler after the reaction is completed. S4, the feed liquid enters the cooler for cooling, and the cooled feed liquid enters the cooling kettle for gas-liquid separation, the gas enters the ammonia recovery system, the liquid overflows the kettle and enters the water separation kettle A / B, water is added to the water separation kettle, the final product is precipitated and filtered to recover the solvent.

2. According to claim S1, the solvent used is a high-boiling point organic nitrogen heterocyclic water-soluble solvent (including but not limited to pyrazole, quinoline, N-methylpyrrolidone, etc.), and the catalyst used is a quaternary ammonium salt phase transfer catalyst (including but not limited to tetrabutylammonium chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, etc.), and the mass ratio is: m-nitrochlorobenzene: solvent: catalyst = 1:2.0-4.0:0.001-0.

01.

3. According to claim S1, the concentration of concentrated ammonia water used is 40-60wt%.

4. According to claim S2, the molar ratio of concentrated ammonia water to m-nitrochlorobenzene chlorine solution entering the mixer is: m-nitrochlorobenzene: ammonia = 1:8.0-10.

0.

5. According to claim S2, the outlet temperature of the heat exchanger is controlled between 110-120°C.

6. According to claim S3, the reaction temperature of the mixed liquid in the fixed bed dynamic tubular reactor is between 190-200°C, and the reaction pressure in the fixed bed dynamic tubular reactor is between 11.0-12.5 MPa.

7. According to claim S3, the catalyst in the fixed bed is a nano-scale porous silicon oxide molecular sieve loaded with a metal catalyst (the loaded catalyst includes but is not limited to cupric chloride, cuprous chloride, aluminum chloride, copper oxide, chromium trioxide, etc.). The fixed bed dynamic tubular reactor is provided with a stirring and dispersing device, the form of which includes but is not limited to a screw propulsion type, a self-priming stirring type, etc. The residence time of the mixed liquid in the fixed bed dynamic tubular reactor is controlled to be 45-60 min.

8. According to claim S4, after the reaction is completed, the feed liquid enters a cooler for cooling, and refrigerated brine is passed through the cooler. The cooler outlet temperature is controlled below 120°C. After being cooled by the cooler, the feed liquid enters a cooling kettle through a submerged pipe, and circulating water is passed through the cooling kettle jacket. The temperature in the cooling kettle is controlled between 80-90°C.

9. According to claim S4, the gas phase on the cooling kettle is removed from the ammonia recovery system through a pressure relief valve. The liquid phase overflows into the water separation kettle A / B. A certain amount of water is first added to the water separation kettle, stirring is turned on, and the overflowing liquid enters the water and is fully stirred and then sent to the filter to filter and obtain the product. The filtrate is sent to the distillation tower to recover the solvent.

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