Preparation method of N, N-dimethyl propane diamine

Abstract

The invention discloses a preparation process of N, N-dimethyl propane diamine in the field of petrochemical engineering, which comprises the following steps: 1) putting a catalyst into a high-pressure reaction kettle, then adding acrylonitrile and dimethylamine, uniformly mixing by a stirrer, and introducing nitrogen; 2) filling ammonia gas into the reactor after the replacement is completed, then heating the high-pressure reaction kettle through jacket steam outside the high-pressure reaction kettle, filling hydrogen into the high-pressure reaction kettle after the heating is completed, and continuously preheating the high-pressure reaction kettle until the reaction is completed; 3) the reaction liquid circulating pump sends part of the reactor outlet material to the external circulation heat exchanger and sends part of the material to the catalyst filter pump; and 4) cooling the material discharged from the external circulation heat exchanger, and returning the cooled material to the high-pressure reaction kettle for continuous reaction. The one-pot circulation process provided by the invention can avoid multi-kettle switching in the synthesis process, simplifies the process flow, reduces the equipment investment, and reduces the operation complexity.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and particularly to a synthesis technology of propanediamine derivatives. Technical Background

[0002] N,N-dimethylpropylamine (DMAPA) is one of the important varieties of lower aliphatic diamines. Due to its strong polarity and active chemical properties, it can be used in a variety of organic synthesis reactions. Generally, it is mainly used as an organic synthesis intermediate to produce surfactants, dyes, ion exchange resins, etc., as an additive for epoxy resins, gasoline, oils, fibers, leather, etc., and can also be used as a preservative, humectant and crosslinking agent in the plastics industry and paper industry, etc. It is a fine chemical with broad application prospects.

[0003] At present, the industrial preparation process of DMAPA uses dimethylamine, acrylonitrile and hydrogen as raw materials, and adopts the Michael addition reaction of acrylonitrile and dimethylamine, and the hydrogenation reduction preparation process of dimethylaminopropionitrile. However, most of them adopt the batch two-step process for production, which has the disadvantages of difficult catalyst regeneration, poor product quality, complex process flow, backward overall production process, and high production cost.

[0004] Currently, the relevant patents on DMAPA mainly focus on aspects such as the type of reactor, optimization of synthesis process conditions, and selection of hydrogenation catalysts.

[0005] Chinese Patent CN105198754B discloses a batch preparation process of DMAPA. First, acrylonitrile and dimethylamine are added to a synthesis reaction kettle for reaction, and then the excess dimethylamine is removed by distillation to obtain dimethylaminopropene nitrile; then hydrogen is introduced into a high-pressure reaction kettle, and a hydrogenation catalyst is added for hydrogenation reduction reaction. After the reaction is complete, sedimentation and distillation are carried out to obtain the DMAPA product.

[0006] Chinese Patent CN101321722B proposes a method for preparing DMAPA on an industrial scale. This method first uses acrylonitrile and dimethylamine as raw materials to carry out an addition reaction in a bubble cap column to prepare dimethylaminopropionitrile; then the concentrated dimethylaminopropionitrile product is obtained by refining at the bottom of the bubble cap column, and finally this product is transferred to an intermittent hydrogenation reactor for catalytic hydrogenation to obtain DMAPA.

[0007] Chinese Patent CN113620813 developed a continuous process technology for microchannel amination combined with fixed-bed hydrogenation. In this method, the addition reaction of dimethylamine and acrylonitrile is first carried out in a microchannel reactor. After the reaction is completed, it is mixed with hydrogen and preheated and then enters a continuous hydrogenation reactor for hydrogenation reaction. In Chinese Patent CN103333073, Meng Qingwei et al. developed a process for continuously preparing DMAPA in a double fixed-bed. Different from Patent CN113620813, in this method, the addition reaction of dimethylamine and acrylonitrile is completed in a fixed-bed reactor, and the subsequent processes are basically similar for both.

[0008] However, the process technologies proposed in Chinese Patents CN105198754B and CN101321722B have high operating costs and poor product quality stability in industrial production. The process technology proposed in Chinese Patent CN103333073 has a long residence time in the addition reaction stage, a large reactor size, and a high equipment investment. Although the microchannel reactor used in the process technology of Patent CN113620813 has a shortened residence time and a reduced equipment size, the cost of the microchannel reactor is high and it is not suitable for large-scale production.

[0009] Therefore, it is very necessary to propose a new process technology for preparing dimethylpropylenediamine, which can reduce the investment in the industrial preparation process of dimethylpropylenediamine, improve the automation degree, and make the product quality more stable. Summary of the Invention

[0010] The present invention aims at the problems existing in the prior art and provides a new process for preparing N,N-dimethylpropylenediamine.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for preparing N,N-dimethylpropylenediamine, comprising the following steps:

[0013] 1) Put the prepared hydrogenation catalyst into a high-pressure reaction kettle, first add acrylonitrile, cool the high-pressure kettle, then add dimethylamine, start stirring to make the materials in the kettle mix evenly, and then fill the high-pressure reaction kettle with nitrogen to displace the air in the kettle;

[0014] 2) After the displacement is completed, fill the high-pressure reaction kettle with ammonia, then heat the high-pressure reaction kettle through the steam in the outer jacket of the reaction kettle. After the heating is completed, fill the high-pressure reaction kettle with hydrogen and continue to preheat the high-pressure reaction kettle until the reaction ends;

[0015] 3) The outlet of the high-pressure reaction kettle is connected to a reaction liquid circulation pump. The reaction liquid circulation pump sends part of the materials at the outlet of the high-pressure reaction kettle to an external circulation heat exchanger and part to a catalyst filtration pump;

[0016] 4) The material coming out of the external circulation heat exchanger is cooled and then returns to the high-pressure reactor to continue the reaction; the material coming out of the catalyst filtration pump enters the primary filter, and after filtration, the catalyst-containing material enters the catalyst metering tank to be mixed with fresh or regenerated catalyst and then sent to the high-pressure reactor; the catalyst-free material enters the secondary filter, and the reaction clear liquid obtained after re-filtration is sent to the crude liquid tank;

[0017] A preparation method of dimethylpropylenediamine according to the present invention is further characterized in that: by circulating heat removal through the external circulation heat exchanger, on the one hand, the load of the jacket of the high-pressure reactor is reduced, and on the other hand, the reaction product is separated from the reaction system, which is beneficial to improving the conversion rate of the reaction raw materials.

[0018] A preparation method of dimethylpropylenediamine according to the present invention is further characterized in that: the mixing mode of the reaction raw materials acrylonitrile and dimethylamine selects a paddle-type stirrer. The stirrer generally consists of parts such as a motor, a paddle, a stirring shaft, and a bearing.

[0019] A preparation method of dimethylpropylenediamine according to the present invention is further characterized in that: the reaction temperature of the high-pressure reactor is 40-140 °C, preferably 80-120 °C. The reaction ammonia partial pressure is 0.01-0.1 MPa, preferably 0.05-0.5 MPa; the hydrogen partial pressure is 0.1-5 MPa, preferably 0.5-3.0 MPa.

[0020] A preparation process method of dimethylpropylenediamine according to the present invention is further characterized in that: the dosage of the catalyst is 0.1 wt% - 3.0 wt%, and the preferred catalyst dosage is 0.5 wt% - 1.5 wt%.

[0021] A preparation process method of dimethylpropylenediamine according to the present invention is further characterized in that: the stirring rate of the stirrer is 300 rpm - 2000 rpm, and the preferred stirring rate is 500 rpm - 1500 rpm.

[0022] A preparation method of N,N-dimethylpropylenediamine according to the present invention is further characterized in that: the hydrogenation catalyst is Raney nickel, Raney copper, Pt / C, Pd / C, and cobalt composite nano-catalyst, preferably Raney nickel or Raney copper composite nano-catalyst. The hydrogenation catalyst can select commercially available catalysts with a wide application range and mature and reliable technology in the market.

[0023] A preparation method of N,N-dimethylpropylenediamine according to the present invention is further characterized in that: the high-pressure autoclave reactor is provided with an ammonia gas inlet and a hydrogen gas inlet. The inlets are located in the middle and lower parts of the high-pressure reactor.

[0024] The positive effects of the technology of the present invention are as follows:

[0025] 1. The one-pot circulation process proposed by the process of the present invention can avoid the multi-kettle switching in the synthesis process, simplify the process flow, reduce equipment investment, and lower the operation complexity.

[0026] 2. The circulating loop formed by the high-pressure reactor, reaction liquid circulation pump, and external circulation heat exchanger in the process of the present invention enables more precise control of parameters such as temperature, residence time, and pressure, enhances the controllability of the reaction process, and improves the effectiveness of the utilization of various resources in the reaction process.

[0027] 3. The process of the present invention is provided with an external circulation heat exchanger, which can reduce the reaction temperature of the high-pressure reactor to a controllable range, avoid the "temperature runaway" of the reactor caused by local hot spots, reduce the generation of heavy components, and thus ensure the yield and quality of the reaction products.

[0028] The following further elaborates on the present invention in conjunction with the drawings and specific embodiments, but does not limit the scope of use of the present invention. Description of the Drawings

[0029] Figure 1 It is a process flow diagram for preparing dimethylpropylenediamine according to the present invention.

[0030] The reference numerals shown therein are: 1 - stirrer, 2 - high-pressure reactor, 3 - reaction liquid circulation pump, 4 - external circulation heat exchanger, 5 - catalyst filtration pump, 6 - primary filter, 7 - catalyst metering tank, 8 - secondary filter, 9 - crude liquid tank, 10 - reaction liquid storage tank, 11 - catalyst preparation tank, 12 - ammonia gas inlet, 13 - hydrogen gas inlet. Specific Embodiments

[0031] The following further elaborates on the present invention in conjunction with the attached Figure 1 The embodiments of the present invention only illustrate the specific circumstances of the implementation of the present invention and do not limit this embodiment.

[0032] As shown in the figure, the preparation method of N,N-dimethylpropylenediamine of the present invention includes the following steps:

[0033] (1) Load the prepared composite nano-catalyst into the high-pressure reactor 2. First, pump acrylonitrile at room temperature, and then after cooling the high-pressure reactor 2 by passing chilled water through the coil in the high-pressure reactor 2, pump in dimethylamine with a slight excess. Fill the reactor with nitrogen to displace the air in the reactor. The percentage of the catalyst in the total mass of the reaction materials is 0.5 wt% - 1.5 wt%, and the molar ratio of the reaction raw materials acrylonitrile and dimethylamine is 1.1 - 1.6;

[0034] (2) The side of the high-pressure reactor 2 is provided with an air inlet. Open the ammonia inlet 12, and gaseous ammonia enters the high-pressure reactor 2 to be stirred and mixed with the liquid-phase material and react. Control the ammonia feeding ratio. After the feeding is completed, open the hydrogen inlet 13 on the side of the high-pressure reactor 2. Gaseous hydrogen is mixed and reacted with the slurry reaction raw materials and the catalyst mixture through a stirrer. Hydrogen is also fed in proportion. After cyclic reaction until the hydrogen feeding ends, a reaction solution containing DMAPA is obtained. The partial pressure of ammonia in the high-pressure reactor 2 is 0.05 - 0.5 MPa, and the partial pressure of hydrogen is 0.5 - 3.0 MPa.

[0035] (3) The high-pressure reactor 2 is equipped with an outer jacket, and steam is introduced into the jacket. During the process of filling ammonia, the reactor is programmed to increase the temperature, and the temperature of the reactor is maintained at 40 - 80 °C. After the ammonia filling is completed, during the process of filling hydrogen, the reactor continuously increases the temperature to the reaction temperature and maintains it until the reaction is completed. The reaction temperature is 80 °C - 120 °C, the programmed temperature increase rate is 30 °C - 45 °C / h, and the reaction time is 1 - 3 h. Steam or cooling water can be introduced into the jacket of the reactor, enabling the jacket to have both heating and cooling functions;

[0036] (4) The reaction product and catalyst slurry from the high-pressure reactor 2 are partially sent to the external circulation heat exchanger 4 through the reaction liquid circulation pump 3. The external circulation heat exchanger 4 controls the temperature through heat exchange to keep the reaction temperature stable. The material finally returns to the high-pressure reactor 2 to continue the reaction, and part of it goes to the catalyst filtration pump 5. The reaction product and catalyst slurry from the catalyst filtration pump 5 enter the primary filter 6 through a pipeline. In the primary filter 6, the reaction clear liquid and the catalyst slurry are separated by solid-liquid separation. The concentrated catalyst slurry enters the catalyst metering tank 7, and after being mixed evenly with the fresh or regenerated catalyst from the catalyst preparation tank 11, it is sent to the high-pressure reactor 2 to continue the reaction. When the activity of the catalyst significantly decreases and the catalyst inside the high-pressure reactor 2 needs to be replaced as a whole, the reaction liquid in the reactor needs to be sent into the reaction liquid storage tank 10 through the reaction liquid circulation pump 3, and after the catalyst is updated, the reaction is restarted. The primary filter 7 is one of a disc filter, a mesh filter, or a basket filter;

[0037] (5) The reaction clear liquid from the primary filter 7 enters the secondary filter 8 with a higher filtration accuracy through a pipeline again. In the secondary filter 8, the reaction clear liquid is filtered with high precision again. The filtered reaction clear liquid is sent to the crude liquid tank 9 as the crude reaction product, and then a qualified DMAPA product is obtained through the refining unit. The filtered catalyst is sent to the catalyst regeneration unit as waste catalyst. The secondary filter 8 is one of a disc filter, a mesh filter, or a basket filter with a higher filtration accuracy;

[0038] Example 1

[0039] Charge the prepared composite nano-catalyst into a high-pressure reactor. The percentage of the catalyst in the total mass of the reaction materials is 1.2 wt%. At room temperature, first pump acrylonitrile into the reactor, and then cool the reactor by passing chilled water through the coil in the reactor. After that, pump in dimethylamine. The molar ratio of acrylonitrile to dimethylamine is 1.2. Start the stirrer and set the stirring rate to 1000 rpm to make the materials in the reactor mix evenly. Subsequently, charge nitrogen into the high-pressure reactor to displace the air in the reactor. There is an air inlet on the side of the high-pressure reactor. After the air in the reactor is displaced, open the ammonia inlet, introduce ammonia and control the ammonia introduction ratio. Set the partial pressure of ammonia to 0.1 MPa. During the introduction of ammonia, ammonia reacts with the liquid-phase materials in the high-pressure reactor with the continuous stirring of the stirrer until the materials become slurry. After the introduction is completed, introduce steam into the jacket of the high-pressure reactor, and the reactor is heated up in a programmed manner, rising from room temperature to 50 °C in 0.5 h. At this time, open the hydrogen inlet. During the charging of hydrogen, the reactor is continuously heated up to 100 °C in 1.5 h. Continuously charge hydrogen and adjust the hydrogen pressure to maintain at 2.0 MPa and react for 2 h. After the reaction, a reaction solution containing DMAPA can be obtained. The conversion rate of acrylonitrile is 100%, and the yield of DMAPA is 91.6%. The reaction products and catalyst slurry from the high-pressure reactor pass through the reaction liquid circulation pump. Part of them goes to the external circulation heat exchanger and finally returns to the high-pressure reactor to continue the reaction, and part goes to the catalyst filtration pump. The reaction products and catalyst slurry from the catalyst filtration pump enter the disc-type primary filter through the pipeline. In the primary filter, the reaction clear liquid and the catalyst slurry are separated by solid-liquid separation. The concentrated catalyst slurry enters the catalyst metering tank and is mixed evenly with the fresh or regenerated catalyst from the catalyst preparation tank and then sent to the high-pressure reactor to continue the reaction. The reaction clear liquid from the primary filter enters the secondary filter with higher filtration accuracy through the pipeline. In the secondary high-precision filter, the reaction clear liquid is filtered again. The filtered reaction clear liquid is sent to the crude liquid tank as the crude reaction product and is subsequently refined by the refining unit to obtain the qualified DMAPA product. The filtered catalyst is sent to the catalyst regeneration unit as waste catalyst;

[0040] Example 2

[0041] Charge the prepared composite nano-catalyst into the high-pressure reactor. The percentage of the catalyst in the total mass of the reaction materials is 1.5 wt%. At room temperature, first pump acrylonitrile into the reactor, and then pass chilled water through the coil in the reactor to cool the reactor. After that, pump dimethylamine into the reactor. The molar ratio of acrylonitrile to dimethylamine is 1.6. Start the stirrer and set the stirring rate to 1500 rpm to make the materials in the reactor mix evenly. Subsequently, charge nitrogen into the high-pressure reactor to displace the air in the reactor. There is an air inlet on the side of the high-pressure reactor. After the air in the reactor is displaced, open the ammonia inlet, pass ammonia into the reactor and control the ammonia feeding ratio, set the partial pressure of ammonia to 0.5 MPa. During the process of passing ammonia, ammonia reacts with the liquid-phase materials in the high-pressure reactor with the continuous stirring of the stirrer until the materials become slurry. After the feeding is completed, pass steam into the jacket of the high-pressure reactor, and the reactor is heated up in a programmed manner, rising from room temperature to 80 °C in 1 h. At this time, open the hydrogen inlet. During the process of charging hydrogen, the reactor is continuously heated up to 120 °C in 1 h. Continuously charge hydrogen and adjust the hydrogen pressure to maintain at 3.0 MPa for 3 h. After the reaction is completed, a reaction solution containing DMAPA is obtained. The conversion rate of acrylonitrile is 100%, and the yield of DMAPA is 85.2%. The reaction products and catalyst slurry from the high-pressure reactor pass through the reaction liquid circulation pump. Part of them goes to the external circulation heat exchanger and finally returns to the high-pressure reactor to continue the reaction, and part goes to the catalyst filtration pump. The reaction products and catalyst slurry from the catalyst filtration pump enter the disc-type primary filter through the pipeline. In the primary filter, the reaction clear liquid and the catalyst slurry are separated by solid-liquid separation. The concentrated catalyst slurry enters the catalyst metering tank and is mixed evenly with the fresh or regenerated catalyst from the catalyst preparation tank and then sent to the high-pressure reactor to continue the reaction. The reaction clear liquid from the primary filter enters the secondary filter with higher filtration accuracy through the pipeline. In the secondary high-precision filter, the reaction clear liquid is filtered again. The filtered reaction clear liquid is sent to the crude liquid tank as the crude reaction product, and the qualified DMAPA product is obtained through the subsequent refining unit. The filtered catalyst is sent to the catalyst regeneration unit as waste catalyst.

[0042] Example 3

[0043] Load the prepared composite nano-catalyst into the high-pressure reactor. The percentage of the catalyst in the total mass of the reaction materials is 0.5 wt%. At room temperature, first pump acrylonitrile into the reactor, and then pass chilled water through the coil in the reactor to cool down the reactor. After that, pump in dimethylamine. The molar ratio of acrylonitrile to dimethylamine is 1.1. Turn on the stirrer and set the stirring rate to 500 rpm to make the materials in the reactor mix evenly. Subsequently, charge nitrogen into the high-pressure reactor to displace the air in the reactor. There is an air inlet on the side of the high-pressure reactor. After the air in the reactor is displaced, open the ammonia inlet, introduce ammonia and control the ammonia introduction ratio. Set the partial pressure of ammonia to 0.05 MPa. During the introduction of ammonia, ammonia reacts with the liquid-phase materials in the high-pressure reactor with the continuous stirring of the stirrer until the materials become slurry. After the introduction is completed, introduce steam into the jacket of the high-pressure reactor, and the reactor is heated up programmatically. It is heated up to 40 °C in 0.5 h. At this time, open the hydrogen inlet. During the charging of hydrogen, the reactor is continuously heated up to 80 °C in 1 h. Continuously charge hydrogen and adjust the hydrogen pressure to maintain at 1.0 MPa for 1 h. After the reaction, a reaction liquid containing DMAPA can be obtained. The conversion rate of acrylonitrile is 100%, and the yield of DMAPA is 80.5%. The reaction products and catalyst slurry from the high-pressure reactor pass through the reaction liquid circulation pump. Part of them goes to the external circulation heat exchanger and finally returns to the high-pressure reactor to continue the reaction, and part goes to the catalyst filtration pump. The reaction products and catalyst slurry from the catalyst filtration pump enter the disk-type primary filter through the pipeline. In the primary filter, the reaction clear liquid and the catalyst slurry are separated by solid-liquid separation. The concentrated catalyst slurry enters the catalyst metering tank and is mixed evenly with the fresh or regenerated catalyst from the catalyst preparation tank and then sent to the high-pressure reactor to continue the reaction. The reaction clear liquid from the primary filter enters the secondary filter with higher filtration accuracy through the pipeline. In the secondary high-precision filter, the reaction clear liquid is filtered again. The filtered reaction clear liquid is sent to the crude liquid tank as the crude reaction product and is subsequently refined by the refining unit to obtain the qualified DMAPA product. The filtered catalyst is sent to the catalyst regeneration unit as the waste catalyst.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of N,N-dimethylpropylenediamine, comprising the following steps: 1) Put the prepared hydrogenation catalyst into a high-pressure reactor. First, add acrylonitrile, cool the high-pressure reactor, and then add dimethylamine. Start stirring to make the materials in the reactor mix evenly. Charge nitrogen into the high-pressure reactor to displace the air in the reactor; 2) After the displacement is completed, charge ammonia into the high-pressure reactor. Subsequently, heat the reactor by the steam in the outer jacket of the high-pressure reactor. After heating is completed, charge hydrogen into the high-pressure reactor and continue to preheat and maintain the temperature of the high-pressure reactor until the reaction ends; 3) The outlet of the high-pressure reactor is connected to a reaction liquid circulation pump. The reaction liquid circulation pump sends part of the materials at the reactor outlet to an external circulation heat exchanger and part to a catalyst filtration pump; 4) The materials coming out of the external circulation heat exchanger return to the high-pressure reactor for continued reaction after temperature control; the materials coming out of the catalyst filtration pump enter a primary filter, After filtration, the catalyst-containing materials enter a catalyst metering tank, are mixed with fresh or regenerated catalyst, and then sent into the high-pressure reactor; the catalyst-free materials enter a secondary filter, and the reaction clear liquid obtained after re-filtration is sent to a crude liquid tank.

2. The preparation method of N,N-dimethylpropylenediamine according to claim 1, characterized in that: The reaction temperature of the high-pressure reactor is 40 - 140 °C, the reaction ammonia partial pressure is 0.01 - 0.1 MPa; the hydrogen partial pressure is 0.1 - 5.0 MPa.

3. The preparation method of N,N-dimethylpropylenediamine according to claim 2, characterized in that: The reaction temperature of the high-pressure reactor is 80 - 120 °C. The reaction ammonia partial pressure is 0.05 - 0.5 MPa; the hydrogen partial pressure is 0.5 - 3.0 MPa.

4. The preparation method of N,N-dimethylpropylenediamine according to claim 1, characterized in that: The dosage of the catalyst is 0.1 wt% - 3.0 wt%, and preferably the dosage of the catalyst is 0.5 wt% - 1.5 wt%.

5. The preparation method of N,N-dimethylpropylenediamine according to claim 1, characterized in that: The stirrer is a paddle stirrer.

6. The preparation method of N,N-dimethylpropylenediamine according to claim 5, characterized in that: The stirring rate of the stirrer is 300 rpm - 2000 rpm, and preferably the stirring rate is 500 rpm - 1500 rpm.

7. The preparation method of N,N-dimethylpropylenediamine according to claim 1, wherein: The hydrogenation catalyst is Raney nickel, Raney copper, Pt / C, Pd / C, and cobalt composite nanocatalyst, and preferably Raney nickel or Raney copper composite nanocatalyst.

8. The preparation method of N,N-dimethylpropylenediamine according to claim 7, characterized in that: The hydrogenation catalyst is Raney nickel or Raney copper composite nanocatalyst.

9. The preparation method of N,N-dimethylpropylenediamine according to claim 1, characterized in that: An air inlet is provided on the high-pressure reactor, and an ammonia inlet and a hydrogen inlet are provided. The air inlet is located in the middle and lower part of the high-pressure reactor.

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