A kind of production method and production system of anilinoacetonitrile

Abstract

The invention discloses a production method and a production system of anilinoacetonitrile. The method comprises: feeding hydroxyacetonitrile, aniline and alkaline catalyst solution into a microreactor and a time-delay reactor in sequence for reaction, cooling the reaction liquid and performing phase separation; recovering the anilinoacetonitrile in the water phase. The system comprises: a microreactor, a time-delay reactor, a cooling mechanism and a phase separation mechanism connected in sequence, the phase separation mechanism is provided with a liquid inlet, a water phase outlet and an oil phase outlet, the water phase outlet is connected with a first vacuum low-temperature evaporation and dehydration device, the first vacuum low-temperature evaporation and dehydration device is provided with a liquid discharge port, the liquid discharge port is connected with the liquid inlet of the phase separation mechanism through a circulation pump, and the oil phase outlet is connected with a cooling granulation device through a second vacuum low-temperature evaporation and dehydration device. Combining a microreactor capable of precisely controlling temperature with a time-delay reactor can avoid the side reactions such as polymerization of the product anilinoacetonitrile caused by local overheating to produce organic matter with a benzene ring, thereby reducing the content of COD.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a production method and a production system of anilinoacetonitrile. Background Art

[0002] Indigo, also known as Food Blue No. 1, Edible Cyan No. 2, Edible Blue, Acid Indigo, Hardened Indigo, etc., is a water-soluble non-azo colorant widely used in food, medicine and printing and dyeing industries.

[0003] Anilinoacetonitrile is an important intermediate for the production of indigo. At present, the domestic industrial production of anilinoacetonitrile generally uses aniline and hydroxyacetonitrile as raw materials, synthesizes anilinoacetonitrile crude product through kettle reaction, adds the crude product into water for cooling crystallization, centrifugal separation to obtain anilinoacetonitrile product, and the mother liquor obtained by centrifugation is subjected to multi-stage sedimentation separation to recover the anilinoacetonitrile in the mother liquor. However, the recovered anilinoacetonitrile is of poor quality and has a high impurity content, which affects the overall quality of anilinoacetonitrile, and the organic impurity content with benzene rings in the mother liquor is high, which is difficult to handle.

[0004] The patent document with publication number CN101514170B discloses a method for preparing anilinoacetonitrile, which continuously and successively passes raw materials aniline and hydroxyacetonitrile through a pipeline preheater, a pipeline mixer, a pipeline reactor and a tank reactor to carry out condensation reaction to generate anilinoacetonitrile. The scheme adopts a tubular continuous and tank-type intermittent reaction to synthesize anilinoacetonitrile, which is an improvement on the synthesis of anilinoacetonitrile by tank reaction, but the mass transfer and heat transfer effect of the pipeline reactor is poor, it is difficult to reach the effective reaction temperature, resulting in incomplete reaction, and the tank reactor must be connected in series, the reaction time is long, the impurity content in the synthesized anilinoacetonitrile reaction liquid is high, and water must be added for cooling crystallization and centrifugation to obtain the anilinoacetonitrile product. However, a large amount of difficult-to-treat mother liquor containing benzene rings and high COD can be discharged in the process, and the purity of the anilinoacetonitrile product is relatively low, only about 60wt%, and it is difficult to make an industrial product that meets the requirements of commercial sale, so it does not have industrial production value.

[0005] Microreactors, or microchannel reactors, are reactors with channel equivalent diameters between 10 and 1000 μm manufactured using precision machining technology. They have excellent heat and mass transfer capabilities, small liquid holdup, no amplification effect, instantaneous uniform mixing of materials, and efficient heat transfer. They have attracted widespread attention in recent years. At present, there have been studies on the preparation of anilinoacetonitrile using microchannel reactors. Good reaction results can be achieved in the pilot stage, with high product purity and yield.

[0006] For example, the patent document with publication number CN104496848B discloses a method for synthesizing anilinoacetonitrile, wherein aniline and hydroxyacetonitrile are continuously subjected to a condensation reaction through a microchannel reactor to generate anilinoacetonitrile, the hydroxyacetonitrile is pretreated with an alkaline catalyst, the molar ratio of the reaction raw materials aniline to hydroxyacetonitrile is 1:1-1.3, the pressure is 0.3-0.7 MPa, the temperature of the reaction module is 130-165°C, the volume flow rate of hydroxyacetonitrile in the microchannel reactor is 20-35 mL / min, and the volume flow rate of aniline is 5-20 mL / min. However, the method for synthesizing anilinoacetonitrile has a small volume flow rate, and the reaction solution still needs to be added to water for cooling and crystallization, which inevitably produces a large amount of difficult-to-treat mother liquor containing benzene rings and high COD, and cannot be industrialized. Summary of the invention

[0007] In view of this, the object of the present invention is to provide a production method and a production system for anilinoacetonitrile, which are used to solve the technical problems that a large amount of difficult-to-treat mother liquor containing benzene rings and high COD is generated and industrial production cannot be achieved when anilinoacetonitrile is produced using existing devices.

[0008] In a first aspect, the present invention provides a method for producing anilinoacetonitrile, comprising:

[0009] Hydroxyacetonitrile, aniline and alkaline catalyst solution are sequentially fed into a microreactor and a time-delay reactor for reaction, and the reaction solution is cooled to a certain temperature and then phase separated to obtain an oil phase, which is a crude anilinoacetonitrile product; and the anilinoacetonitrile in the water phase is recovered.

[0010] Optionally, the alkaline catalyst solution is preheated before being fed into the microreactor.

[0011] Optionally, the alkaline catalyst is selected from sodium hydroxide, sodium carbonate or sodium bicarbonate.

[0012] Optionally, the concentration of the alkaline catalyst solution is 0.5 wt% to 5 wt%, preferably 1 wt% to 5 wt%.

[0013] Optionally, an automatic phase separator or a liquid-liquid phase separation centrifuge is used for phase separation.

[0014] Optionally, the recovery of anilinoacetonitrile in the aqueous phase comprises: vacuum low-temperature evaporation and dehydration of the aqueous phase, phase separation of the concentrated liquid obtained after dehydration, and granulation of the oil phase obtained by the phase separation treatment after vacuum low-temperature evaporation and dehydration.

[0015] Optionally, the catalyst solution is preheated to 60-150°C, preferably 100-150°C.

[0016] Optionally, aniline is preheated to 60-150°C, preferably 100-150°C.

[0017] Optionally, the molar ratio of aniline to hydroxyacetonitrile is 1:1.00 to 1:1.05, preferably 1:1.02 to 1:1.05.

[0018] Optionally, in the total amount of aniline, hydroxyacetonitrile and the alkaline catalyst solution, the proportion of hydroxyacetonitrile is 30 wt % to 55 wt %, preferably 30 wt % to 50 wt %.

[0019] Optionally, the flow rate of the hydroxyacetonitrile is 0.1 to 120 L / min, preferably 40 to 90 L / min.

[0020] Optionally, in the microreactor, the reaction temperature is 150-180° C., preferably 160-180° C.; the reaction pressure is 0.7-2.0 MPa, preferably 1.0-1.5 MPa; and the reaction residence time is 20-70 s, preferably 30-70 s.

[0021] Optionally, in the delayed reactor, the reaction temperature is 120-150° C., preferably 130-150° C.; the reaction pressure is 0.7-2.0 MPa, preferably 1.0-1.5 MPa; and the reaction residence time is 300-1800 s, preferably 600-1800 s.

[0022] Optionally, when an automatic phase separator is used for phase separation, the temperature of phase separation is 40 to 60°C, preferably 40 to 50°C.

[0023] Optionally, the reaction solution is cooled to 40-60°C, preferably 40-50°C.

[0024] Optionally, the vacuum degree of the vacuum low-temperature evaporation dehydration is 0.1-10 kPa, preferably 1-10 kPa; the temperature of the vacuum low-temperature evaporation dehydration is 40-60°C, preferably 50-60°C.

[0025] Optionally, the production method further comprises the following step: subjecting the obtained crude oil-phase anilinoacetonitrile to vacuum low-temperature evaporation and dehydration.

[0026] Optionally, after subjecting the obtained crude oil phase anilinoacetonitrile to vacuum low-temperature evaporation dehydration, the method further comprises the following steps: cooling the solid obtained after dehydration and then granulating it to obtain granular anilinoacetonitrile.

[0027] In another aspect, the present invention also provides a production system used in the production method as described above, comprising:

[0028] A mixer, a microreactor, a time-delay reactor, a cooling mechanism and a phase separation mechanism are connected in sequence. The phase separation mechanism is provided with a liquid inlet, a water phase outlet and an oil phase outlet. The water phase outlet is connected to a first vacuum low-temperature evaporation and dehydration device. The first vacuum low-temperature evaporation and dehydration device is provided with a liquid discharge port. The liquid discharge port is connected to the liquid inlet of the phase separation mechanism through a circulation pump. One end of the mixer away from the microreactor is connected to two preheaters, and the two preheaters are used to preheat hydroxyacetonitrile and an alkaline catalyst solution respectively.

[0029] The working principle of the production system of the present invention is as follows:

[0030] When the production system of the present invention is used to produce anilinoacetonitrile, two preheaters preheat aniline and an alkaline catalyst solution respectively, and then perform preliminary mixing in a mixer to obtain an aniline-alkaline catalyst solution mixed solution; the preheat treatment can prevent the material entering the flow microreactor from being locally overheated, thereby preventing the reaction product anilinoacetonitrile from undergoing side reactions such as polymerization and decomposition at high temperature to produce impurities such as organic matter with a benzene ring, thereby reducing the amount of COD generated. The mixer can premix the preheated aniline and the alkaline catalyst solution, thereby improving the mixing uniformity of the material entering the microreactor, thereby improving the reaction efficiency.

[0031] The aniline-alkaline catalyst solution mixture and hydroxyacetonitrile are mixed evenly and instantaneously in the microreactor, and good mass transfer and heat transfer are carried out in the microreactor, so that the aniline and hydroxyacetonitrile react completely, and the contents of aniline and hydroxyacetonitrile in the reaction solution are greatly reduced; at the same time, the microreactor can realize precise temperature control, avoid the occurrence of local overheating and the like, and further avoid the reaction product aniline acetonitrile from undergoing side reactions such as decomposition and polymerization under high temperature, and produce impurities such as organic matter with benzene rings, thereby reducing the COD content in the reaction solution.

[0032] After the reaction, the materials enter the delayed reactor, and the unreacted aniline and hydroxyacetonitrile continue to react in the delayed reactor. The good heat transfer and mass transfer effects of the delayed reactor promote a more thorough reaction of aniline and hydroxyacetonitrile, further reducing the content of aniline and hydroxyacetonitrile in the reaction solution.

[0033] After the reaction, the material enters the cooling mechanism from the delayed reactor and is cooled in the cooling mechanism, thereby preventing the reaction product anilinoacetonitrile from crystallizing at high temperature and from polymerizing, decomposing and other side reactions under high temperature to produce impurities such as organic matter with benzene rings.

[0034] After cooling, the material enters the phase separation structure for phase separation, and obtains an anilinoacetonitrile oil phase containing a small amount of water and an anilinoacetonitrile water phase containing a small amount of water.

[0035] The anilinoacetonitrile oil phase flowing out from the oil phase outlet of the phase separation mechanism enters the cooling granulation device, and is cooled in the cooling granulation device to obtain a granular anilinoacetonitrile product.

[0036] The water phase flowing out from the water phase outlet of the phase separation mechanism enters the first vacuum low-temperature evaporation and dehydration device to remove water from the anilinoacetonitrile oil phase under low temperature conditions, which can prevent the heat-sensitive substance anilinoacetonitrile from undergoing polymerization, decomposition and other side reactions under high temperature to produce impurities such as organic matter with a benzene ring, thereby improving the purity of the final product anilinoacetonitrile; and the concentrated liquid obtained after removing water is recycled and processed by the phase separation mechanism, which can improve the yield of the final product anilinoacetonitrile.

[0037] Optionally, the microreactor adopts a large-flux continuous flow microreactor. The large-flux continuous flow microreactor is provided with a cold and hot medium baffle channel at the inlet near the feed port and the outlet near the discharge port. The cold and hot medium baffle channel can ensure good heat transfer performance, thereby achieving accurate control of mass transfer and heat transfer of aniline, hydroxyacetonitrile and catalyst solution, further avoiding the occurrence of local overheating and other phenomena, thereby avoiding the side reactions such as decomposition and polymerization of the anilinoacetonitrile produced by the reaction at high temperature to produce impurities such as organic matter with benzene rings, and further reducing the amount of COD produced in the reaction solution.

[0038] Optionally, the delayed reactor is a differential side flow reactor.

[0039] Optionally, the phase separation mechanism adopts an automatic phase separator or a liquid-liquid phase separation centrifuge.

[0040] Optionally, the mixer is a pipeline mixer.

[0041] Optionally, the first vacuum low-temperature evaporation and dehydration device includes an evaporator, and the evaporator is a falling film evaporator, a forced circulation reboiler or a siphon reboiler, preferably a falling film evaporator. The falling film evaporator forms a film in the tubes, has excellent heat exchange effect, and does not cause the decomposition and polymerization of the heat-sensitive substance anilinoacetonitrile to produce impurities such as organic matter with benzene rings, thereby further reducing the amount of COD generated.

[0042] Optionally, the production system further comprises a cooling granulation device, wherein the cooling granulation device is connected to the oil phase outlet of the phase separation mechanism.

[0043] Optionally, it further comprises a second vacuum low-temperature evaporation and dehydration device, which is arranged between the oil phase outlet of the phase separation mechanism and the cooling and granulation device.

[0044] Optionally, the second vacuum low-temperature evaporation and dehydration device includes an evaporator, and the evaporator is a falling film evaporator, a forced circulation reboiler or a siphon reboiler, preferably a falling film evaporator. The falling film evaporator forms a film in the tubes, has excellent heat exchange effect, and does not cause the decomposition and polymerization of the heat-sensitive substance anilinoacetonitrile to produce impurities such as organic matter with benzene rings, thereby further reducing the amount of COD generated.

[0045] Optionally, the mixer is a pipeline mixer.

[0046] As described above, the production method and production system of anilinoacetonitrile of the present invention have the following beneficial effects:

[0047] (1) The present invention can avoid local overheating of materials entering a large-flux continuous flow microreactor by heat-treating aniline and an alkaline catalyst solution, and avoid the reaction product anilinoacetonitrile from undergoing decomposition, polymerization and other side reactions at high temperatures to produce impurities such as organic matter with a benzene ring, thereby reducing the amount of COD generated.

[0048] (2) The present invention can premix the preheated aniline and the alkaline catalyst solution through a mixer, further improving the mixing uniformity of the materials entering the microreactor, thereby improving the reaction efficiency.

[0049] (3) The present invention combines a microreactor and a time-delayed reactor with excellent mass transfer and heat transfer effects, which can make aniline and hydroxyacetonitrile react completely, greatly reducing the content of aniline and hydroxyacetonitrile in the reaction solution; at the same time, the microreactor and the time-delayed reactor can achieve precise temperature control, thereby avoiding the occurrence of local overheating and the like, thereby avoiding the reaction product anilinoacetonitrile from undergoing polymerization, decomposition and other side reactions under high temperature to produce impurities such as organic matter with a benzene ring, thereby reducing the COD content in the reaction product.

[0050] (4) The present invention separates the cooled material into an anilinoacetonitrile oil phase containing a small amount of water and an aqueous phase containing a small amount of anilinoacetonitrile through a phase separation mechanism, removes water from the anilinoacetonitrile oil phase under low temperature conditions, avoids the heat-sensitive substance anilinoacetonitrile from undergoing polymerization, decomposition and other side reactions under high temperature to produce impurities such as organic matter with a benzene ring, and improves the purity of the final product anilinoacetonitrile; removes water from the aqueous phase under low temperature conditions, and the obtained concentrated liquid is recycled and treated by the phase separation mechanism to improve the yield of the final product anilinoacetonitrile; and the water vapor obtained by vacuum low-temperature evaporation and dehydration of the aqueous phase has a small organic content and a low COD content, which is easy to handle. After condensation, it can be directly discharged and sent to the sewage treatment system, and can meet the discharge standards after treatment. Therefore, the production system of the present invention is used to produce anilinoacetonitrile, and no high-concentration, difficult-to-treat crystallization mother liquor is generated, and the clean production of the device is realized, which has environmental advantages.

[0051] (5) The production system of the present invention does not need to add a water cooling crystallization device (intermittent crystallization operation, multiple equipment, and a large device), a solid-liquid separation device, a mother liquor sedimentation recovery device, and a high-concentration mother liquor treatment device, which simplifies the process flow, saves investment, and reduces the energy consumption of the device operation.

[0052] (6) Compared with the existing device, the present invention realizes the full continuous production of anilinoacetonitrile. Through automated control measures, manual operation is not required at the production site, which improves production safety and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The structure diagram of the anilinoacetonitrile production system of Example 1 is shown;

[0054] Figure 2 This is a schematic diagram of the process flow of Example 2;

[0055] Figure 3 The schematic diagram of the structure of the anilinoacetonitrile production system of Example 8;

[0056] Figure 4 This is a schematic diagram of the process flow of Example 9.

[0057] Reference numerals

[0058] 1 preheater; 2 mixer; 3 metering pump;

[0059] 401 integrated mixer, 402 parallel microchannel reactor; 403 cold and hot medium baffle channel; 404 micro-reaction channel; 405 discharge port; 4061 first feed port; 4062 second feed port; A cold and hot medium inlet; B cold and hot medium outlet;

[0060] 5 delayed reactor; 6 cooling mechanism; 7 phase separation mechanism; 8 cooling granulation device; 9 water vapor collecting tank; 10 first vacuum low-temperature evaporation dehydration device; 11 circulation pump; 12 second vacuum low-temperature evaporation dehydration device. DETAILED DESCRIPTION

[0061] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0062] The present invention provides a method for producing anilinoacetonitrile, comprising the following steps:

[0063] Preheating a 0.5 wt% to 5 wt% alkaline catalyst solution to 60 to 150° C., wherein the alkaline catalyst is selected from sodium hydroxide, sodium carbonate or sodium bicarbonate;

[0064] Preheat aniline to 60-150°C;

[0065] Then, hydroxyacetonitrile, aniline and alkaline catalyst solution are introduced into a microreactor for reaction at a temperature of 150-180° C. and a pressure of 0.7-2.0 MPa. In the microreactor, the reaction residence time is 20-70 seconds, and the molar ratio of aniline to hydroxyacetonitrile is 1:1.00-1:1.05, preferably 1:1.02-1:1.05; in the sum of aniline, hydroxyacetonitrile and alkaline catalyst solution, the proportion of hydroxyacetonitrile is 30wt%-55wt%, preferably 30wt%-50wt%, and the flow rate of hydroxyacetonitrile is 0.1-120L / min, preferably 40-90L / min;

[0066] Then, the reaction liquid obtained from the microreactor is sent to a time-delay reactor for reaction at 120-150° C. and a pressure of 0.7-2.0 MPa. In the time-delay reactor, the reaction residence time is 300-1800 s.

[0067] Then, the reaction solution obtained in the extended time reactor is cooled to 40-60°C;

[0068] Then, an automatic phase separator or a liquid-liquid phase separation centrifuge is used for phase separation. When an automatic phase separator is used for phase separation, the phase separation temperature is 40 to 60° C., preferably 40 to 50° C.;

[0069] The obtained oil phase is subjected to vacuum low-temperature evaporation and dehydration under the conditions of a vacuum degree of 0.1 to 10 kPa and a temperature of 40 to 60° C., followed by cooling and granulation. The obtained water phase is subjected to vacuum low-temperature evaporation and dehydration under the conditions of a vacuum degree of 0.1 to 10 kPa and a temperature of 40 to 60° C., and the obtained concentrated liquid is subjected to phase separation using an automatic phase separator or a liquid-liquid phase separation centrifuge. When the automatic phase separator is used for phase separation, the phase separation temperature is 40 to 60° C., preferably 45 to 50° C. The oil phase obtained by phase separation is subjected to vacuum low-temperature evaporation and dehydration under the conditions of a vacuum degree of 0.1 to 10 kPa and a temperature of 40 to 60° C., followed by cooling and granulation to obtain granular anilinoacetonitrile.

[0070] The present invention also provides a production system adopted by the production method of anilinoacetonitrile as described above, comprising:

[0071] The invention discloses a mixer, a microreactor, a time-delay reactor, a cooling mechanism and a phase-separation mechanism which are connected in sequence. The phase-separation mechanism is provided with a liquid inlet, a water phase outlet and an oil phase outlet. The oil phase outlet is connected with a cooling granulation device. The water phase outlet is connected with a first vacuum low-temperature evaporation and dehydration device. The first vacuum low-temperature evaporation and dehydration device is provided with a liquid discharge port, which is connected with the liquid inlet of the phase-separation mechanism via a circulation pump. The mixer adopts a pipeline mixer. Two preheaters are connected with one end of the mixer away from the microreactor. The two preheaters are respectively used to preheat hydroxyacetonitrile and an alkaline catalyst solution. The microreactor adopts a large-flux continuous flow microreactor. The time-delay reactor adopts a differential side flow reactor. The phase-separation mechanism adopts an automatic phase separator or a liquid-liquid phase separation centrifuge. The first vacuum low-temperature evaporation and dehydration device comprises an evaporator. The evaporator adopts a falling film evaporator, a forced circulation reboiler or a siphon reboiler.

[0072] In another embodiment of the present invention, the production system also includes a second vacuum low-temperature evaporation and dehydration device, which is arranged between the oil phase outlet of the phase separation mechanism and the cooling granulation device. The second vacuum low-temperature evaporation and dehydration device includes an evaporator, and the evaporator adopts a falling film evaporator, a forced circulation reboiler or a siphon reboiler.

[0073] The present invention is described in detail below by specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0074] In the present invention, the aniline content in the anilinoacetonitrile oil phase is detected according to "HG / T 5285-2017 Anilinoacetonitrile Standard";

[0075] The purity of granular anilinoacetonitrile products is tested in accordance with the "HG / T 5285-2017 Anilinoacetonitrile Standard";

[0076] The yield of anilinoacetonitrile is as follows: Calculation is performed, wherein X represents the yield of anilinoacetonitrile, a represents the mass of the granular anilinoacetonitrile product, in kg, b represents the mass of the raw material aniline, in kg, A represents the content of anilinoacetonitrile in the granular anilinoacetonitrile product, i.e., the purity of the granular anilinoacetonitrile product, in wt%, and B represents the purity of the raw material aniline (obtained from the outer packaging), in wt%;

[0077] The COD content is tested in accordance with "GB11914-89 Determination of Chemical Oxygen Demand".

[0078] Example 1

[0079] like Figure 1 As shown, this embodiment provides a system for producing anilinoacetonitrile. The production system is used to produce anilinoacetonitrile.

[0080] The anilinoacetonitrile production system of the present embodiment comprises a mixer 2, a microreactor, a time-delay reactor 5, a cooling mechanism 6 and a phase separation mechanism 7 which are connected in sequence by pipelines, and one end of the mixer 2 away from the microreactor is connected to two preheaters 1 via a metering pump 3.

[0081] The two preheaters 1 are used to preheat aniline and alkaline catalyst solution respectively. The preheating treatment can avoid local overheating of the materials entering the microreactor, thereby preventing the reaction product aniline acetonitrile from undergoing decomposition, polymerization and other side reactions at high temperature to produce impurities such as organic matter with benzene rings, thereby reducing the amount of COD generated.

[0082] The mixer 2 can premix the preheated aniline and the alkaline catalyst solution, thereby improving the mixing uniformity of the materials entering the microreactor and improving the reaction efficiency.

[0083] The microreactor specifically adopts a large-throughput continuous flow microreactor (D-AMERT reactor), which is used as a reaction container for aniline, hydroxyacetonitrile and alkaline catalyst solution, and includes a logistics precision distributor (not shown in the figure), an integrated mixer 401, and a parallel microchannel reactor 402. The logistics precision distributor is connected to the integrated mixer 401, and the parallel microchannel reactor 402 includes a plurality of microreaction channels 404 arranged in parallel.

[0084] The precise logistics distributor is used to evenly distribute the material into a number of liquid flows equal in number to the micro-reaction channels 404, and the integrated mixer 401 is used to mix the material.

[0085] The micro-reaction channel 404 is provided with a first feed port, a second feed port and a discharge port 405. The size and number of the micro-reaction channel 404 can be designed according to the characteristics and flow rate of the material. The first feed port and the second feed port of the micro-reaction channel 404 are both provided with an integrated mixer 401.

[0086] Cold and hot medium baffle channels 403 are provided at the cold and hot medium inlet A near the first feed port 4061 and the second feed port 4062 and at the cold and hot medium outlet B near the discharge port 405. The cold and hot medium enter from the cold and hot medium inlet A and are discharged from the cold and hot medium outlet B, which can ensure good heat transfer performance and thus achieve precise control of the mass transfer and heat transfer of aniline, hydroxyacetonitrile and catalyst solution, thereby avoiding local overheating and the like, avoiding the reaction product aniline acetonitrile from undergoing decomposition, polymerization and other side reactions at high temperature to produce impurities such as organic matter with benzene rings, thereby reducing the amount of COD generated.

[0087] The time-delayed reactor 5 is specifically a differential baffled reactor (i.e., a DSR reactor). The differential baffled reactor (i.e., a DSR reactor) is used to allow the unreacted aniline and hydroxyacetonitrile to continue to react under the catalytic action of the alkaline catalyst solution. It has excellent mass transfer and heat transfer effects, and can make the aniline and hydroxyacetonitrile react more thoroughly.

[0088] The production system of this embodiment combines a microreactor with excellent mass transfer and heat transfer effects and a time-delay reactor 5, which can make aniline and hydroxyacetonitrile react thoroughly, greatly reducing the content of aniline and hydroxyacetonitrile in the reaction solution; at the same time, the microreactor and the time-delay reactor 5 can achieve precise temperature control to avoid local overheating and other phenomena, thereby preventing the reaction product anilinoacetonitrile from undergoing polymerization, decomposition and other side reactions under high temperature to produce impurities such as organic matter with benzene rings, thereby reducing the COD content in the reaction solution.

[0089] The cooling mechanism 6 is used to cool the reaction liquid obtained from the time-delay reactor 5 to 40-60° C., so as to prevent the heat-sensitive substance anilinoacetonitrile from undergoing side reactions such as decomposition and polymerization at high temperatures to produce impurities such as organic matter with benzene rings, thereby reducing the amount of COD generated. The cooling mechanism 6 can be a tube-and-tube cooler, a plate cooler, an air-cooled cooler, etc. The tube-and-tube cooler, the plate cooler, and the air-cooled cooler are prior arts and will not be described in detail herein.

[0090] The phase separation mechanism 7 is used to separate the liquid into an oil phase (containing a small amount of water, the main component of which is anilinoacetonitrile) and an aqueous phase (containing a small amount of anilinoacetonitrile). The phase separation mechanism 7 adopts an automatic phase separator or a liquid-liquid phase separation centrifuge. The phase separation mechanism 7 is provided with a liquid inlet, an oil phase outlet and an aqueous phase outlet. The oil phase outlet and the aqueous phase outlet are respectively connected to a cooling granulation device 8 and a first vacuum low-temperature evaporation and dehydration device 10. The first vacuum low-temperature evaporation and dehydration device 10 is provided with a liquid discharge port, and the liquid discharge port is connected to the liquid inlet of the phase separation mechanism 7 through a circulation pump 11.

[0091] The oil phase outlet B of the phase separation mechanism 7 is connected to a cooling granulation device 8. The cooling granulation device 8 can be a spray dryer, which is a prior art and will not be described in detail here. The cooling granulation device 8 is used to cool the anilinoacetonitrile oil phase from the oil phase outlet B of the phase separation mechanism 7. During the cooling process, the liquid anilinoacetonitrile oil phase material is atomized and contacts and transfers heat with cold air or an inert gas, and the liquid anilinoacetonitrile oil phase material is rapidly cooled to obtain a granular anilinoacetonitrile product.

[0092] The first vacuum low-temperature evaporation and dehydration device 10 includes an evaporator, a vapor-liquid separation chamber, a circulation pump, a vacuum pump, etc. The vacuum low-temperature evaporation and dehydration device is a prior art and will not be described here. The evaporator adopts a falling film evaporator, a forced circulation reboiler or a siphon reboiler. Part of anilinoacetonitrile is dissolved in the water phase. The water phase from the water phase outlet of the phase separation mechanism 7 is placed in the first vacuum low-temperature evaporation and dehydration device 10 for treatment. The water evaporates continuously during the treatment process. The anilinoacetonitrile gradually tends to saturation or even supersaturation due to the reduction of water and then precipitates. The obtained concentrated liquid is pumped into the phase separation mechanism 7 through the circulation pump 11 for phase separation treatment, and the anilinoacetonitrile in the water phase can be recovered to improve the yield of anilinoacetonitrile; secondly, the water vapor obtained by evaporation has less organic matter content and low COD, and can be directly sent to the sewage device for subsequent treatment after condensation; furthermore, dehydration under vacuum and low temperature conditions can avoid the anilinoacetonitrile from decomposing and polymerizing at high temperature to produce byproducts such as organic matter with benzene rings and reduce the amount of COD produced.

[0093] Example 2

[0094] The production system of Example 1 is used to prepare anilinoacetonitrile, and the specific steps are as follows:

[0095] The alkaline catalyst solution and aniline are preheated to 110° C. and 120° C. respectively by two preheaters 1; the concentration of the alkaline catalyst solution is 2 wt %, and the alkaline catalyst is sodium hydroxide;

[0096] The preheated alkaline catalyst solution and aniline enter the mixer 2 and are evenly mixed in the mixer 2 to obtain an aniline-alkaline catalyst solution mixture, and then the aniline-alkaline catalyst solution mixture and hydroxyacetonitrile are respectively fed into the microreactor through the first feed port 4061 and the second feed port 4062, wherein the feed amount of aniline is 27.44 L / min, the feed amount of hydroxyacetonitrile is 52.32 L / min, and the proportion of hydroxyacetonitrile in the total amount of aniline, hydroxyacetonitrile and alkaline catalyst solution is 31.21 wt%;

[0097] The logistics precision distributor divides the amine-alkaline catalyst solution mixture and hydroxyacetonitrile into multiple streams of materials equal to the number of micro-reaction channels 404, and evenly distributes them to each integrated mixer 401 through the first feed port 4061 and the second feed port 4062 respectively; the integrated mixer 401 evenly mixes the materials from the logistics precision distributor at the moment of entering the parallel micro-reaction channel reactor 402, and ensures that they do not contact each other before entering the micro-reaction channel 404. The aniline-alkaline catalyst solution mixture and hydroxyacetonitrile enter the parallel micro-reaction channel After entering the reactor 402, the hot and cold media flow in from the hot and cold media inlet A near the first feed port 4061 and the second feed port 4062, and are discharged from the hot and cold media outlet B near the outlet 405, thereby ensuring the precise control of the heat transfer and mass transfer effects of the reaction materials, so that aniline and hydroxyacetonitrile react efficiently and quickly in the micro-reaction channel 404 to generate anilinoacetonitrile, which is discharged from the outlet 405. The temperature of the micro-reactor is 176.25° C., the back pressure is 1.15 MPa, and the reaction residence time is 63.94 s.

[0098] The reacted material discharged from the discharge port 405 of the microreactor enters the delayed reactor 5, and the unreacted aniline and hydroxyacetonitrile continue to react in the delayed reactor 5. The good heat transfer and mass transfer effects of the delayed reactor 5 promote a more thorough reaction of aniline and hydroxyacetonitrile, further reducing the content of aniline and hydroxyacetonitrile in the reaction solution. The temperature of the delayed reactor 5 is 143.21° C., the back pressure is 1.15 MPa, and the reaction residence time is 25.07 s.

[0099] After the reaction, the material enters the cooling mechanism 6 from the time-delay reactor 5 and is cooled in the cooling mechanism 6.

[0100] The temperature is set to 50°C, which prevents the reaction product anilinoacetonitrile from crystallizing at high temperature and from undergoing side reactions such as polymerization and decomposition at high temperature to produce impurities such as organic matter with benzene rings;

[0101] After cooling, the material enters the phase separation structure 7 for phase separation to obtain an anilinoacetonitrile oil phase containing a small amount of water and an aqueous phase containing a small amount of anilinoacetonitrile, wherein in the phase separation structure 7, the temperature of the phase separation treatment is 50° C., the feed rate of the material is 79.76 L / min, the anilinoacetonitrile oil phase production is 36.15 L / min, the aqueous phase production is 42.32 L / min, and the aniline content in the anilinoacetonitrile oil phase is 0.06 wt%;

[0102] The anilinoacetonitrile oil phase flowing out from the oil phase outlet of the phase separation mechanism 7 enters the cooling granulation device 8, and is cooled in the cooling granulation device 8 to obtain a granular anilinoacetonitrile product. In the cooling granulation device 8, the feed rate of the anilinoacetonitrile oil phase is 40.87 L / min, and the content of anilinoacetonitrile in the obtained granular anilinoacetonitrile product is 96.57 wt%, and the output of the granular anilinoacetonitrile product is 2452.05 kg / h;

[0103] The water phase flowing out from the water phase outlet of the phase separation mechanism 7 enters the first vacuum low-temperature evaporation and dehydration device 10, and the water in the anilinoacetonitrile oil phase is removed under low temperature conditions. The obtained concentrated liquid is pumped into the phase separation mechanism 7 through a circulation pump 11 for phase separation treatment. The obtained anilinoacetonitrile oil phase flows out from the oil phase outlet of the phase separation mechanism 7 and enters the cooling granulation device 8. After cooling in the cooling granulation device 8, a granular anilinoacetonitrile product is obtained. In the first vacuum low-temperature evaporation and dehydration device 10, the water phase feed rate is 53.62 L / min, the temperature is 46.55°C, the vacuum degree is 4.27 kPa, the concentrated liquid output is 12.37 L / min, the condensed water (i.e., the condensed water obtained after condensation of water vapor) output is 40.74 L / min, and the feed rate of the concentrated liquid entering the phase separation mechanism 7 is 12.37 L / min.

[0104] Embodiments 3 to 7

[0105] Except the conditions shown in Table 1-5, produce anilinoacetonitrile in the same manner as Example 2.

[0106] Table 1 Feed parameters in microreactor

[0107]

[0108]

[0109] Table 2 Reaction conditions in microreactor and delayed reactor

[0110]

[0111] Table 3 Condition parameters in the phase separation mechanism

[0112]

[0113] Table 4 Condition parameters in cooling granulation device

[0114]

[0115]

[0116] Table 5 Parameters of the first vacuum low-temperature dehydration device (i.e., parameters of low-temperature evaporation and dehydration of water phase)

[0117]

[0118] Example 8

[0119] like Figure 2 The aniline acetonitrile production system shown in the embodiment is different from the embodiment 1 in that it also includes a second vacuum low-temperature evaporation and dehydration device 12, and the second vacuum low-temperature evaporation and dehydration device 12 is arranged between the oil phase outlet of the phase separation mechanism 7 and the cooling granulation device 8.

[0120] The second vacuum low-temperature evaporation and dehydration device 12 includes an evaporator, a vapor-liquid separation chamber, a circulation pump, a vacuum pump, etc. The vacuum low-temperature evaporation and dehydration device is a prior art and is not described in detail here. The evaporator adopts a falling film evaporator, a forced circulation reboiler or a siphon reboiler, for example, a falling film evaporator, which evaporates in a tube array, has an excellent heat exchange effect, and does not cause the polymerization, decomposition and other side reactions of the heat-sensitive substance anilinoacetonitrile to produce impurities such as organic matter with a benzene ring, further reducing the amount of COD generated. The heat medium of the falling film evaporator can be hot water, thermal oil, ethylene glycol aqueous solution and other substances. Since water can be dissolved in the anilinoacetonitrile oil phase, the anilinoacetonitrile oil phase from the oil phase outlet of the phase separation mechanism 7 is placed in the second vacuum low-temperature evaporation and dehydration device 12, and dehydrated under vacuum and low-temperature conditions, which can prevent the anilinoacetonitrile from undergoing side reactions such as decomposition and polymerization at high temperatures to produce by-products such as organic matter with benzene rings, thereby reducing the amount of COD generated and, at the same time, also improving the purity of the final product anilinoacetonitrile.

[0121] Example 9

[0122] The production system of Example 8 was used to prepare anilinoacetonitrile. The difference between this example and Example 3 is that in the microreactor, the feed amount of aniline is 26.45 L / min, the feed amount of hydroxyacetonitrile is 50.43 L / min, the temperature of the microreactor is 175.21° C., the back pressure is 1.21 MPa, and the reaction residence time is 66.33 s.

[0123] The temperature of the extended reactor 5 was 144.52°C, the back pressure was 1.21 MPa, and the reaction residence time was 26.01 s;

[0124] In phase separation structure 7, the feed rate of the material is 76.88 L / min, the output of the anilinoacetonitrile oil phase is 35.89 L / min, the output of the water phase is 53.23 L / min, and the aniline content in the anilinoacetonitrile oil phase is 0.07 wt%;

[0125] The anilinoacetonitrile oil phase flowing out of the oil phase outlet of the phase separation mechanism 7 is evaporated and dehydrated at low temperature by the second vacuum low temperature evaporation and dehydration device 12, and the dehydrated melt enters the cooling granulation device 8, where it is cooled and granulated;

[0126] In the second vacuum low-temperature evaporation dehydration device 12, the feed rate of anilinoacetonitrile oil phase is 35.89 L / min, the temperature is 47.55°C, the vacuum degree is 3.16 kPa, and the melt extraction rate is 34.84 L / min;

[0127] In the cooling granulation device 8, the feed rate of the anilinoacetonitrile oil phase is 34.84 L / min, and the content of anilinoacetonitrile in the obtained granular anilinoacetonitrile product is 99.57 wt %, and the output of the granular anilinoacetonitrile product is 2299.73 kg / h;

[0128] In the first vacuum low-temperature evaporation dehydration device 10, the water phase feed rate is 53.23 L / min, the temperature is 47.55°C, the vacuum degree is 4.23 kPa, the concentrated liquid output is 12.24 L / min, the condensed water output is 40.30 L / min, and the feed rate of the concentrated liquid entering the phase separation mechanism 7 is 12.24 L / min.

[0129] Examples 10-14

[0130] Except for the conditions shown in Table 6-11, anilinoacetonitrile was produced in the same manner as in Example 9.

[0131] Table 6 Feed parameters in microreactor

[0132] source Hydroxyacetonitrile percentage, % Aniline feed, L / min Hydroxyacetonitrile feed, L / min Example 9 31.21 26.45 50.43 Example 10 35.60 29.33 49.03 Embodiment 11 38.54 35.12 54.23 Example 12 40.21 43.45 64.30 Embodiment 13 44.41 55.76 74.72 Embodiment 14 47.33 65.12 81.88

[0133] Table 7 Reaction conditions in microreactor and delayed reactor

[0134]

[0135] Table 8 Condition parameters in the phase separation mechanism

[0136]

[0137]

[0138] Table 9 Parameters of the second vacuum low temperature dehydration device (i.e., low temperature evaporation dehydration parameters of the aniline acetonitrile oil phase)

[0139]

[0140] Table 10 Condition parameters in cooling granulation device

[0141]

[0142] Table 11 Parameters of the first vacuum low-temperature dehydration device (i.e., parameters of low-temperature evaporation and dehydration of water phase)

[0143]

[0144] Index detection

[0145] The COD content in the condensed water collected in the water vapor collection tank 9 was detected by the production methods of Examples 2-7 and 9-14 to produce anilinoacetonitrile. The test results are shown in Table 12.

[0146] The yield of anilinoacetonitrile produced by the production methods of Examples 2-7 and 9-14 was tested, and the test results are shown in Table 12;

[0147] The purity of the granular anilinoacetonitrile obtained in Examples 2-7 was tested, and the test results are shown in Table 12; the granular anilinoacetonitrile products obtained by two granulation processes in Examples 9-14 were mixed, and the purity of the mixed granular anilinoacetonitrile products was tested, and the results are shown in Table 12.

[0148] Table 12 Test results

[0149]

[0150] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for producing anilinoacetonitrile, characterized in that: include: The hydroxyacetonitrile, aniline and alkaline catalyst solution are sequentially fed into a microreactor and a time-delay reactor for reaction, and the reaction solution is cooled to a certain temperature and then phase-separated to obtain an oil phase, which is a crude anilinoacetonitrile product; the anilinoacetonitrile in the water phase is recovered, and the time-delay reactor adopts a differential side-flow reactor; Before feeding the alkaline catalyst solution into the microreactor, the alkaline catalyst solution is preheated; Before feeding aniline into the microreactor, the aniline is preheated; The method for recovering the anilinoacetonitrile in the water phase comprises: subjecting the obtained water phase to vacuum low-temperature evaporation and dehydration, subjecting the obtained concentrated liquid to phase separation, and subjecting the obtained oil phase to vacuum low-temperature evaporation and dehydration and then granulating.

2. The production method according to claim 1, characterized in that The alkaline catalyst is selected from sodium hydroxide, sodium carbonate or sodium bicarbonate; and / or, the concentration of the alkaline catalyst solution is 0.5wt%~5wt%; And / or, phase separation is performed using an automatic phase separator or a liquid-liquid phase separation centrifuge.

3. The production method according to claim 2, characterized in that: Preheat the alkaline catalyst solution to 60-150°C; And / or, preheat aniline to 60-150°C.

4. The production method according to claim 1, characterized in that The molar ratio of aniline to hydroxyacetonitrile is 1:1.00 to 1:1.05; and / or, in the sum of aniline, hydroxyacetonitrile and the alkaline catalyst solution, the proportion of hydroxyacetonitrile is 30wt% to 55wt%; And / or, in the microreactor, the flow rate of hydroxyacetonitrile is 0.1-120 L / min; And / or, in the microreactor, the reaction temperature is 150-180° C., the reaction pressure is 0.7-2.0 MPa, and the reaction residence time is 20-70 s; And / or, in the delayed reactor, the reaction temperature is 120-150° C., the reaction pressure is 0.7-2.0 MPa, and the reaction residence time is 300-1800 s; And / or, when an automatic phase separator is used for phase separation, the temperature of the phase separation is 40-60°C.

5. The production method according to claim 1, characterized in that: Cool the reaction solution to 40-60°C; And / or, the vacuum degree of the vacuum low-temperature evaporation dehydration is 0.1-10 kPa, and the temperature of the vacuum low-temperature evaporation dehydration is 40-60°C.

6. The production method according to claim 1, characterized in that: The following steps are also included: The obtained crude oil phase anilinoacetonitrile is subjected to vacuum low-temperature evaporation and dehydration.

7. The production method according to claim 6, characterized in that After the obtained crude oil phase anilinoacetonitrile is subjected to vacuum low-temperature evaporation and dehydration, the method further comprises the following steps: cooling the dehydrated melt and then granulating it to obtain granular anilinoacetonitrile.

8. A system for producing anilinoacetonitrile, characterized in that: include: A mixer, a microreactor, a time-delay reactor, a cooling mechanism and a phase separation mechanism are connected in sequence. The phase separation mechanism is provided with a liquid inlet, a water phase outlet and an oil phase outlet. The water phase outlet is connected to a first vacuum low-temperature evaporation and dehydration device. The first vacuum low-temperature evaporation and dehydration device is provided with a liquid discharge port. The liquid discharge port is connected to the liquid inlet of the phase separation mechanism through a circulation pump. One end of the mixer away from the microreactor is connected to two preheaters, and the two preheaters are used to preheat hydroxyacetonitrile and an alkaline catalyst solution respectively. The time-delay reactor adopts a differential side flow reactor.

9. The anilinoacetonitrile production system according to claim 8, characterized in that: The mixer is a pipeline mixer; And / or, the microreactor is a large-flux continuous flow microreactor; And / or, the phase separation mechanism adopts an automatic phase separator or a liquid-liquid phase separation centrifuge; And / or, the first vacuum low-temperature evaporation and dehydration device comprises an evaporator, and the evaporator is a falling film evaporator, a forced circulation reboiler or a siphon reboiler; And / or, it also includes a cooling granulation device, which is connected to the oil phase outlet of the phase separation mechanism.

10. The anilinoacetonitrile production system according to claim 9, characterized in that: It also includes a second vacuum low-temperature evaporation and dehydration device, which is arranged between the oil phase outlet of the phase separation mechanism and the cooling and granulation device.

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