Method and device for continuously catalytically hydrogenating to prepare 2,4-diaminoanisole

Abstract

The present invention relates to the field of the production and preparation of 2,4-diaminoanisole, and specifically, it is a method and device for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole based on a micro-packed bed. The catalyst Pd(OH)2 / C is filled in the micro-packed bed reactor of the device described in claim 1; the air in the device is replaced by nitrogen, and then the reaction materials are added. In the presence of nitrogen, the reaction materials and hydrogen react at 25-125 °C and a pressure of 1.0-3.0 MPa to obtain 2,4-diaminoanisole. The device of the present invention uses a micro-packed bed reactor, which has a larger gas-liquid-solid three-phase contact area and higher heat and mass transfer capabilities compared to a conventional autoclave reactor, can more precisely control the reaction process, and shorten the reaction cycle.

Description

Technical Field

[0001] The present invention relates to the field of the production and preparation of 2,4-diaminoanisole, and specifically to a method and device for continuously catalytic hydrogenation of 2,4-diaminoanisole based on a micro-packed bed. Background Art

[0002] 2,4-Diaminoanisole is an important organic synthesis intermediate, which is widely used in fine chemical fields such as dyes, pharmaceuticals, and pesticides.

[0003] 2,4-Diaminoanisole is obtained by hydrogenation reduction of 2,4-dinitroanisole. 2,4-Dinitroanisole contains two unsaturated nitro groups. Since the conversion of the first nitro group (electron-withdrawing group) to an amino group (electron-donating group) will reduce the electron deficiency in the ring, it hinders the further reduction of the second nitro group, making it difficult to achieve complete conversion to 2,4-diaminoanisole. The traditional industrial technology for producing 2,4-diaminoanisole is: using Raney nickel as a catalyst and hydrogen as a reducing agent to carry out a hydrogenation reduction reaction in a batch autoclave to obtain the product. However, the use conditions of Raney nickel are relatively harsh and dangerous. At the same time, a certain amount of wastewater and solid waste will be generated during the reaction process, causing serious environmental pollution. Zhao Xiaoming et al. achieved the hydrogenation reaction of 2,4-dinitroanisole using a Pd / C catalyst, but the reaction time of this process is long and the number of times the catalyst can be reused is small.

[0004] Many studies have shown that it is difficult to obtain satisfactory results for aromatic dinitro compounds in a batch reactor only by using the method of catalyst modification. Patent CN108218728A discloses a method for preparing 2,4-diaminoanisole. This method uses Pd / Al2O3 as a catalyst to carry out continuous hydrogenation in series in a kettle and uses membrane filtration to separate the catalyst, with high production efficiency and product quality. However, the catalyst needs to be continuously supplemented during the reaction process, and complicated and time-consuming sedimentation and filtration operations are also required. Patent CN111302949A discloses a process for preparing phenylenediamine by microreaction technology. The nitroarene to be reduced, solvent, catalyst, and hydrogen are continuously fed into a hydrogenation microreactor after metering to carry out a hydrogenation reduction reaction, with a good yield. However, when the catalyst enters the microreactor in the form of a suspension, it is easy to settle and block the pipeline, and complicated catalyst separation and recovery operations are required. Patent CN113402395A provides a microreactor based on a fixed bed for the hydrogenation of m-dinitrobenzene, but the yield of m-phenylenediamine is relatively low. Moreover, the gas-liquid materials are heated only after entering the micro-packed bed pipeline and it takes a certain time to reach the reaction temperature. Summary of the Invention

[0005] In view of the above technical problems and deficiencies existing in the art, the present invention aims to provide a method and device for continuously catalytic hydrogenation of 2,4-diaminoanisole based on a micro-packed bed with high production efficiency, high completeness, and environmental friendliness.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A device for continuously catalytic hydrogenation of 2,4-diaminoanisole, comprising a nitrogen input pipeline, a hydrogen input pipeline, a three-way valve (4), a liquid material input pipeline, a micro-mixing heat exchanger (9), a micro-packed bed reactor (11), and a gas-liquid separator (13). The micro-mixing heat exchanger (9) is provided with a gas material inlet (901), a liquid material inlet (902), and a gas-liquid mixture outlet (905). The nitrogen input pipeline, the hydrogen input pipeline, and the gas material inlet (901) are respectively connected to the corresponding ports on the three-way valve (4). The liquid material inlet (902) is connected to the liquid material input pipeline. The gas-liquid mixture outlet (905), the micro-packed bed reactor (11), and the gas-liquid separator (13) are connected in series through pipelines in sequence. 2,4-dinitroanisole is dissolved in an organic solvent to prepare a liquid material and is input through the liquid material input pipeline. The inside of the micro-packed bed reactor (11) is provided with a catalyst chamber and a heat exchange medium chamber, and the heat exchange medium chamber surrounds the catalyst chamber. A Pd(OH)2 / C catalyst is provided in the catalyst chamber.

[0008] The inside of the micro-mixing heat exchanger (9) is provided with a mixing channel (906) and a heat exchange medium arranged around the mixing channel (906). The gas material inlet (901) and the liquid material inlet (902) are both communicated with the input end of the mixing channel (906). The output end of the mixing channel (906) is communicated with the gas-liquid mixture outlet (905).

[0009] The mixing channel (906) in the micro-mixing heat exchanger (9) includes a first mixing section and a second mixing section. The first mixing section includes a shunt unit (9061) and a converging unit (9062) arranged alternately. In the second mixing section, a first shunt block (9064) and a second shunt block (9063) are arranged alternately, and the second shunt block (9063) is larger than the first shunt block (9064).

[0010] The micro-mixing heat exchanger (9) is provided with a first heat exchange medium inlet (903) and a first heat exchange medium outlet (904), and both the first heat exchange medium inlet (903) and the first heat exchange medium outlet (904) are communicated with the cavity of the micro-mixing heat exchanger (9) for containing the heat exchange medium.

[0011] One end of the micro-packed bed reactor (11) is provided with a reactor inlet (1101), and the other end is provided with a reactor outlet (1106). The first end of the catalyst chamber is connected to the reactor inlet (1101), and a first sieve plate (1102) is arranged inside the first end. The second end of the catalyst chamber is connected to the reactor outlet (1106), and a second sieve plate (1105) is arranged inside the second end.

[0012] The micro-packed bed reactor (11) is provided with a second heat exchange medium inlet (1103) and a second heat exchange medium outlet (1104), and both the second heat exchange medium inlet (1103) and the second heat exchange medium outlet (1104) are communicated with the heat exchange medium chamber.

[0013] A gas mass flow controller (5) and a pressure gauge (6) are arranged on the connecting pipeline between the three-way valve (4) and the micro-mixing heat exchanger (9). A high-pressure pump (7) and a one-way valve (8) are arranged on the liquid material input pipeline. A back pressure valve (12) is arranged on the gas-liquid separator (13). Thermometers (10) are arranged on the pipelines between the micro-mixing heat exchanger (9) and the micro-packed bed reactor (11) and on the pipelines between the micro-packed bed reactor (11) and the gas-liquid separator (13).

[0014] A method for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole by using the device. The catalyst Pd(OH)2 / C is filled in the micro-packed bed reactor of the device according to claim 1. The air in the device is replaced with nitrogen, and then reaction materials are added. The reaction materials and hydrogen react under the conditions of 25-125 °C and a pressure of 1.0-3.0 MPa in the presence of nitrogen to prepare 2,4-diaminoanisole.

[0015] The reaction materials are 2,4-dinitroanisole dissolved in an organic solvent. Among them, the final concentration of 2,4-dinitroanisole in the reaction materials is 0.2-0.6 mol / L. The organic solvent is tetrahydrofuran or ethyl acetate.

[0016] In the Pd(OH)2 / C catalyst, the proportion of Pd(OH)2 is 7%. The carrier is micro-nano spherical activated carbon with an average particle size of 0.6 mm. The average particle size of the catalyst is 600 nm, and the specific surface area of the catalyst is not less than 800 m 2 / g.

[0017] The reaction materials are added into the reactor at a flow rate of 0.4-1.6 ml / min. Hydrogen is added into the reactor at a flow rate of 40-70 ml / min.

[0018] Advantages and positive effects of the present invention:

[0019] 1. The device of the present invention uses a micro-packed bed reactor, which has a larger gas-liquid-solid three-phase contact area and higher heat and mass transfer capabilities compared to conventional batch reactors. It can more precisely control the reaction process and shorten the reaction cycle.

[0020] 2. The device of the present invention uses a micro-mixing heat exchanger, which has both high-efficiency gas-liquid mixing ability and high-efficiency preheating ability. High-efficiency gas-liquid mixing can evenly distribute the gas-liquid of the material and avoid local overheating caused by uneven mixing of the material subsequently. High-efficiency preheating enables the gas-liquid mixed material to quickly reach the required temperature.

[0021] 3. The present invention uses a Pd(OH)2 / C catalyst supported on micro-nano spherical activated carbon particles. The catalyst has high activity, stable performance, and high selectivity for hydrogenation reactions. When this method is applied to the hydrogenation of 2,4-dinitroanisole, the conversion rate is 100%, the selectivity is greater than 97%, and the best can reach 99.53%.

[0022] 4. The process flow of the present invention is simple. The catalyst is fixed in the micro-packed bed reactor, and subsequent catalyst separation operations are not required. Continuous hydrogenation is achieved, production efficiency is improved, and labor intensity is reduced. No three wastes are generated during the reaction process, which is conducive to resource conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the present invention,

[0024] Figure 2 is Figure 1 the external schematic diagram of the micro-mixing heat exchanger in

[0025] Figure 3 is Figure 2 the internal structural schematic diagram of the micro-mixing heat exchanger in

[0026] Figure 4 is Figure 1 the external schematic diagram of the micro-packed bed reactor in

[0027] Figure 5 is Figure 4 the internal structural schematic diagram of the micro-packed bed reactor in.

[0028] Among them, 1 is a high-pressure nitrogen cylinder, 2 is a high-pressure hydrogen cylinder, 3 is a gas path control ball valve, 4 is a three-way valve, 5 is a gas mass flow controller, 6 is a pressure gauge, 7 is a high-pressure pump, 8 is a check valve, 9 is a micro-mixing heat exchanger, 901 is a gas material inlet, 902 is a liquid material inlet, 903 is a first heat exchange medium inlet, 904 is a first heat exchange medium outlet, 905 is a gas-liquid mixture outlet, 906 is a mixing channel, 9061 is a shunt unit, 9062 is a converging unit, 9063 is a second shunt block, 9064 is a first shunt block, 907 is a communication channel, 10 is a thermometer, 11 is a micro-packed bed reactor, 1101 is a reactor inlet, 1102 is a first sieve plate, 1103 is a second heat exchange medium inlet, 1104 is a second heat exchange medium outlet, 1105 is a second sieve plate, 1106 is a reactor outlet, 12 is a back pressure valve, and 13 is a gas-liquid separator.

[0029] Figure 6 It is an electron microscope image of the catalyst provided by the embodiment of the present invention. Detailed implementation manners

[0030] The present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] As Figures 1 to 5 shown, the present invention includes a nitrogen input pipeline, a hydrogen input pipeline, a three-way valve 4, a liquid material input pipeline, a micro-mixing heat exchanger 9, a micro-packed bed reactor 11, and a gas-liquid separator 13. Among them, as Figures 2 to 3 shown, the micro-mixing heat exchanger 9 is provided with a gas material inlet 901, a liquid material inlet 902, and a gas-liquid mixture outlet 905. The inside of the micro-mixing heat exchanger 9 is provided with a mixing channel 906 and a heat exchange medium filled around the mixing channel 906. The gas material inlet 901 and the liquid material inlet 902 are both communicated with the input end of the mixing channel 906, and the output end of the mixing channel 906 is communicated with the gas-liquid mixture outlet 905. As Figure 1 shown, the nitrogen input pipeline, the hydrogen input pipeline, and the gas material inlet 901 are respectively connected to the corresponding ports on the three-way valve 4. The liquid material inlet 902 is connected to the liquid material input pipeline, and the gas-liquid mixture outlet 905, the micro-packed bed reactor 11, and the gas-liquid separator 13 are connected in series through pipelines in sequence.

[0033] As Figure 3As shown, the mixing channel 906 in the micro-mixing heat exchanger 9 includes a first mixing section and a second mixing section. The first mixing section includes a diverging unit 9061 and a converging unit 9062 arranged alternately. In this embodiment, the diverging unit 9061 includes two diverging channels arranged in a diamond shape. After the material flows into the diverging unit 9061, it is divided into two streams and flows along different diverging channels, and then converges again and flows out into the single channel of the next converging unit 9062, thereby realizing continuous divergence and convergence of the material, and further realizing material mixing. Since the first mixing section is the preliminary mixing of liquid material and gas material, the present invention realizes a large degree of divergence and convergence of the two materials through the alternately arranged diverging unit 9061 and converging unit 9062 to ensure sufficient mixing.

[0034] As Figure 3 shown, in the second mixing section, a first diverging block 9064 and a second diverging block 9063 are arranged alternately. In this embodiment, both the first diverging block 9064 and the second diverging block 9063 are circular, and the diameter of the second diverging block 9063 is larger than that of the first diverging block 9064. When the material flows through the first diverging block 9064 and the second diverging block 9063 in the second mixing section, the material flows through the gaps between the two sides of the first diverging block 9064 and the tube wall of the second mixing section and the gaps between the two sides of the second diverging block 9063 and the tube wall of the second mixing section in sequence, thereby realizing continuous divergence and convergence of the material, and further realizing material mixing. Since the material enters the second mixing section after being fully mixed in the first mixing section, the present invention uses the first diverging block 9064 and the second diverging block 9063 with different diameters to realize a relatively small degree of divergence and convergence of the material with a changing amplitude, so as to ensure stable mixing and sufficient heat exchange of the material in the second mixing section.

[0035] As Figure 3 shown, a communication channel 907 is provided in the micro-mixing heat exchanger 9, and the gas material inlet 901 and the liquid material inlet 902 are respectively communicated with the input end of the mixing channel 906 through different communication channels 907, and the communication channel 907 is placed in the heat exchange medium.

[0036] As Figures 2 to 3 shown, a first heat exchange medium inlet 903 and a first heat exchange medium outlet 904 are provided on the micro-mixing heat exchanger 9, and both the first heat exchange medium inlet 903 and the first heat exchange medium outlet 904 are communicated with the cavity for containing the heat exchange medium in the micro-mixing heat exchanger 9. In this embodiment, the heat exchange medium is high-temperature water.

[0037] As Figures 4 to 5As shown, a catalyst chamber is provided inside the micro-packed bed reactor 11, and a Pd(OH)2 / C catalyst is provided in the catalyst chamber. In the Pd(OH)2 / C catalyst, the proportion of Pd(OH)2 is 7%, the carrier is spherical activated carbon with an average particle size of 0.6 nm, and the specific surface area of the catalyst is 712.3 m 2 / g.

[0038] As Figures 4 to 5 shown, one end of the micro-packed bed reactor 11 is provided with a reactor inlet 1101, and the other end is provided with a reactor outlet 1106. The first end of the catalyst chamber is connected to the reactor inlet 1101, and a first sieve plate 1102 is provided inside the first end. The second end of the catalyst chamber is connected to the reactor outlet 1106, and a second sieve plate 1105 is provided inside the second end. The first sieve plate 1102 and the second sieve plate 1105 are used to prevent the catalyst from flowing out. As Figure 1 shown, the reactor inlet 1101 is communicated with the gas-liquid mixture outlet 905 of the micro-mixing heat exchanger 9 through a pipeline, and the reactor outlet 1106 is communicated with the gas-liquid separator 13.

[0039] As Figures 4 to 5 shown, a heat exchange medium chamber is provided inside the micro-packed bed reactor 11, and the heat exchange medium chamber is arranged around the catalyst chamber. The micro-packed bed reactor 11 is provided with a second heat exchange medium inlet 1103 and a second heat exchange medium outlet 1104, and both the second heat exchange medium inlet 1103 and the second heat exchange medium outlet 1104 are communicated with the heat exchange medium chamber.

[0040] As Figure 1 shown, the input end of the nitrogen input pipeline is connected to the high-pressure nitrogen cylinder 1, and the output end is connected to the corresponding port of the three-way valve 4. The input end of the hydrogen input pipeline is connected to the high-pressure hydrogen cylinder 2, and the output end is connected to the corresponding port of the three-way valve 4. Gas path control ball valves 3 are provided on both the nitrogen input pipeline and the hydrogen input pipeline.

[0041] As Figure 1 shown, a gas mass flow controller 5 and a pressure gauge 6 are provided on the connecting pipeline between the three-way valve 4 and the micro-mixing heat exchanger 9. The gas mass flow controller 5 and the pressure gauge 6 are used to control the flow rate and pressure of the gas material input into the micro-mixing heat exchanger 9. The gas mass flow controller 5 and the pressure gauge 6 are both well-known technologies in the art and are commercially available products.

[0042] As Figure 1As shown, a high-pressure pump 7 and a check valve 8 are provided on the liquid material input pipeline. The high-pressure pump 7 is used to pump the liquid material into the micro-mixing heat exchanger 9. Both the high-pressure pump 7 and the check valve 8 are well-known technologies in the art and are commercially available products. In this embodiment, 2,4-dinitroanisole is dissolved in an organic solvent to prepare a liquid material, and the organic solvent can be tetrahydrofuran or ethyl acetate.

[0043] As Figure 1 shown, thermometers 10 are provided on the pipeline between the micro-mixing heat exchanger 9 and the micro-packed bed reactor 11 and on the pipeline between the micro-packed bed reactor 11 and the gas-liquid separator 13 to detect the temperature of the input or output materials. The thermometers 10 are well-known technologies in the art and are commercially available products.

[0044] As Figure 1 shown, a back pressure valve 12 is provided on the gas-liquid separator 13. The back pressure valve 12 is a well-known technology in the art and is a commercially available product.

[0045] Example 2:

[0046] Step 1: Using the device described in the above example, Pd(OH)2 / C catalyst is filled in the micro-packed bed reactor. The catalyst filling amount is 1 g, which is filled to the middle of the pipeline, and the rest is filled with a blank carrier (micro-nano spherical activated carbon).

[0047] The catalyst Pd(OH)2 / C is prepared by the deposition-precipitation method. Among them, the proportion of Pd(OH)2 in the Pd(OH)2 / C catalyst is 7%, the carrier is micro-nano spherical activated carbon, the average particle size is 600 nm, and the specific surface area of the catalyst is 712.3 m 2 / g (see Figure 6 ).

[0048] Step 2: Then, open the nitrogen input pipeline under normal pressure, set the nitrogen flow rate to 100 mL / min for 3 min to displace the air in the pipeline, purge the air in the pipeline with nitrogen, and protect the catalyst in the nitrogen atmosphere, and check the system tightness.

[0049] Step 3: Dissolve 2,4-dinitroanisole in ethyl acetate to prepare a reaction solution with a concentration of 0.2 mol / L.

[0050] Step 4: Turn on the cooling and heating circulator and set the reaction temperature to 60 °C.

[0051] Step 5: Set the pressure value of the back pressure valve to 2.0 MPa, open the hydrogen input pipeline, open the hydrogen valve, and set the flow parameter of the gas mass flow controller to 50 mL / min.

[0052] Step 6: Set the flow rate of the high-pressure pump to 0.5 mL / min. When the temperature of the cooling and heating circulator reaches the set temperature of 60 °C, turn on the high-pressure pump and inject the liquid material prepared in Step 3 into the reaction system.

[0053] Step 7: After the system stabilizes, collect samples from the liquid outlet of the gas-liquid separator.

[0054] After the reaction is completed, rinse the catalyst and the reactor with methanol, then purge with nitrogen to remove the methanol, and protect the catalyst under a nitrogen atmosphere. The reaction products of this example are analyzed by gas chromatography: the reaction conversion rate is 100%, and the selectivity is 97.62%.

[0055] Example 3:

[0056] The difference from Example 2 is as follows:

[0057] Step 1: Using the device described in the above example, fill the Pd(OH)2 / C catalyst in the micro-packed bed reactor. The filling amount of the catalyst is 1 g, which is filled in the middle of the pipeline, and the rest is filled with a blank carrier (micro-nano spherical activated carbon).

[0058] Step 2: Then, open the nitrogen input pipeline under normal pressure, set the nitrogen flow rate to 100 mL / min for 3 minutes to displace the air in the pipeline with nitrogen, purge the air in the pipeline, and protect the catalyst under a nitrogen atmosphere, and check the system tightness.

[0059] Step 3: Dissolve 2,4-dinitroanisole in tetrahydrofuran to prepare a reaction solution with a concentration of 0.2 mol / L.

[0060] Step 4: Turn on the cooling and heating circulator and set the reaction temperature to 60 °C.

[0061] Step 5: Set the back pressure valve pressure value to 2 MPa, turn on the hydrogen input pipeline, open the hydrogen valve, and set the flow rate parameter of the gas mass flow controller to 96 mL / min.

[0062] Step 6: Set the flow rate of the high-pressure pump to 1.6 mL / min. When the temperature of the cooling and heating circulator reaches the set temperature of 60 °C, turn on the high-pressure pump and inject the liquid material prepared in Step 3 into the reaction system.

[0063] Step 7: After the system stabilizes, collect samples from the liquid outlet of the gas-liquid separator.

[0064] After the reaction is completed, rinse the catalyst and the reactor with methanol, then purge with nitrogen to remove the methanol, and protect the catalyst under a nitrogen atmosphere. The reaction products of this example are analyzed by gas chromatography: the reaction conversion rate is 100%, and the selectivity is 98.98%.

[0065] Example 4:

[0066] The difference from Example 2 is as follows:

[0067] Step 1: Using the device described in the above example, Pd(OH)2 / C catalyst is filled in the micro-packed bed reactor. The filling amount of the catalyst is 0.5 g, which is filled to the middle of the pipeline, and the rest is filled with a blank carrier (micro-nano spherical activated carbon).

[0068] Step 2: Subsequently, open the nitrogen input pipeline under normal pressure, set the nitrogen flow rate to 100 mL / min for 3 min, use nitrogen to purge the air in the pipeline, protect the catalyst in a nitrogen atmosphere, and check the system tightness.

[0069] Step 3: Dissolve 2,4-dinitroanisole in tetrahydrofuran to prepare a reaction solution with a concentration of 0.6 mol / L.

[0070] Step 4: Turn on the cooling and heating circulator and set the reaction temperature to [temperature value] °C.

[0071] Step 5: Set the back pressure valve pressure value to 1.0 MPa, open the hydrogen input pipeline, open the hydrogen valve, and set the flow parameter of the gas mass flow controller to 60 mL / min.

[0072] Step 6: Set the high-pressure pump flow rate to 1.2 mL / min. When the cooling and heating circulator reaches the set temperature of 55 °C, turn on the high-pressure pump and inject the liquid material prepared in Step 3 into the reaction system.

[0073] Step 7: After the system is stable, collect samples from the liquid outlet of the gas-liquid separator.

[0074] After the reaction, rinse the catalyst and the reactor with methanol, then purge the methanol with nitrogen, and protect the catalyst in a nitrogen atmosphere. The reaction products of this example are analyzed by gas chromatography: the reaction conversion rate is 100%, and the selectivity is 98.16%.

[0075] Example 5:

[0076] The difference from Example 2 is as follows:

[0077] Step 1: Using the device described in the above example, Pd(OH)2 / C catalyst is filled in the micro-packed bed reactor. The filling amount of the catalyst is 1.0 g, which is filled to the middle of the pipeline, and the rest is filled with a blank carrier (micro-nano spherical activated carbon).

[0078] Step 2: Subsequently, open the nitrogen input pipeline under normal pressure, set the nitrogen flow rate to 100 mL / min for 3 min, use nitrogen to purge the air in the pipeline, protect the catalyst in a nitrogen atmosphere, and check the system tightness.

[0079] Step 3: Dissolve 2,4-dinitroanisole in tetrahydrofuran to prepare a reaction solution with a concentration of 0.2 mol / L.

[0080] Step 4: Turn on the cooling and heating circulator and set the reaction temperature to 55 °C.

[0081] Step 5: Set the back pressure valve pressure value to 2 MPa, open the hydrogen input pipeline, open the hydrogen valve, and set the flow parameter of the gas mass flow controller to 60 mL / min.

[0082] Step 6: Set the high-pressure pump flow rate to 1 mL / min. When the cooling and heating circulator reaches the set temperature of 55 °C, turn on the high-pressure pump and inject the liquid material prepared in Step 3 into the reaction system.

[0083] Step 7: After the system stabilizes, collect the sample from the liquid outlet of the gas-liquid separator.

[0084] After the reaction, rinse the catalyst and the reactor with methanol, then purge with nitrogen to remove methanol, and protect the catalyst under a nitrogen atmosphere. The reaction product of this example is analyzed by gas chromatography: the reaction conversion rate is 100%, and the selectivity is 99.53%.

[0085] Example 6:

[0086] The difference from Example 2 is as follows:

[0087] Step 1: Using the device described in the above example, fill the Pd(OH)2 / C catalyst in the micro-packed bed reactor. The catalyst filling amount is 1.0 g, which is filled in the middle of the pipeline, and the rest is filled with a blank carrier (micro-nano spherical activated carbon).

[0088] Step 2: Subsequently, open the nitrogen input pipeline under normal pressure, purge the air in the pipeline with nitrogen, protect the catalyst under a nitrogen atmosphere, and check the system tightness.

[0089] Step 3: Dissolve 2,4-dinitroanisole in tetrahydrofuran to prepare a reaction solution with a concentration of 0.2 mol / L.

[0090] Step 4: Turn on the cooling and heating circulator and set the reaction temperature to 55 °C.

[0091] Step 5: Set the back pressure valve pressure value to 3 MPa, open the hydrogen input pipeline, open the hydrogen valve, and set the flow parameter of the gas mass flow controller to 60 mL / min.

[0092] Step 6: Set the high-pressure pump flow rate to 1 mL / min. When the cooling and heating circulator reaches the set temperature of 55 °C, turn on the high-pressure pump and inject the liquid material prepared in Step 3 into the reaction system.

[0093] Step 7: After the system is stable, collect samples from the liquid outlet of the gas-liquid separator.

[0094] After the reaction, rinse the catalyst and the reactor with methanol, then purge with nitrogen to discharge the methanol, and protect the catalyst under a nitrogen atmosphere. The reaction products of this example were analyzed by gas chromatography: the reaction conversion rate was 100%, and the selectivity was 98.07%.

Claims

1. An apparatus for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole, characterized in that: It includes a nitrogen input pipeline, a hydrogen input pipeline, a three-way valve (4), a liquid material input pipeline, a micro-mixing heat exchanger (9), a micro-packed bed reactor (11) and a gas-liquid separator (13). The micro-mixing heat exchanger (9) is provided with a gas material inlet (901), a liquid material inlet (902) and a gas-liquid mixture outlet (905). The nitrogen input pipeline, the hydrogen input pipeline and the gas material inlet (901) are respectively connected to the corresponding ports on the three-way valve (4). The liquid material inlet (902) is connected to the liquid material input pipeline. The gas-liquid mixture outlet (905), the micro-packed bed reactor (11) and the gas-liquid separator (13) are connected in series through pipelines in sequence. 2,4-dinitroanisole is dissolved in an organic solvent to prepare a liquid material and is input through the liquid material input pipeline. The micro-packed bed reactor (11) is internally provided with a catalyst chamber and a heat exchange medium chamber, and the heat exchange medium chamber surrounds the catalyst chamber. A Pd(OH)2 / C catalyst is provided in the catalyst chamber. The micro-mixing heat exchanger (9) is internally provided with a mixing channel (906) and a heat exchange medium arranged around the mixing channel (906). The gas material inlet (901) and the liquid material inlet (902) are both communicated with the input end of the mixing channel (906). The output end of the mixing channel (906) is communicated with the gas-liquid mixture outlet (905). The mixing channel (906) in the micro-mixing heat exchanger (9) includes a first mixing section and a second mixing section. The first mixing section includes a shunt unit (9061) and a convergence unit (9062) arranged alternately. First shunt blocks (9064) and second shunt blocks (9063) are alternately arranged in the second mixing section, and the second shunt block (9063) is larger than the first shunt block (9064). The micro-mixing heat exchanger (9) is provided with a first heat exchange medium inlet (903) and a first heat exchange medium outlet (904), and the first heat exchange medium inlet (903) and the first heat exchange medium outlet (904) are both communicated with the cavity in the micro-mixing heat exchanger (9) that contains the heat exchange medium.

2. The apparatus for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole according to claim 1, wherein: One end of the micro-packed bed reactor (11) is provided with a reactor inlet (1101), and the other end is provided with a reactor outlet (1106). The first end of the catalyst chamber is connected to the reactor inlet (1101), and a first sieve plate (1102) is provided in the first end. The second end of the catalyst chamber is connected to the reactor outlet (1106), and a second sieve plate (1105) is provided in the second end.

3. The apparatus for continuously catalytically hydrogenating to prepare 2,4-diaminoanisole according to claim 1, characterized in that: The micro-packed bed reactor (11) is provided with a second heat exchange medium inlet (1103) and a second heat exchange medium outlet (1104), and the second heat exchange medium inlet (1103) and the second heat exchange medium outlet (1104) are both communicated with the heat exchange medium chamber.

4. The apparatus for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole according to claim 1, wherein: A gas mass flow controller (5) and a pressure gauge (6) are provided on the connecting pipeline between the three-way valve (4) and the micro-mixing heat exchanger (9). A high-pressure pump (7) and a check valve (8) are provided on the liquid material input pipeline. A back pressure valve (12) is provided on the gas-liquid separator (13). Thermometers (10) are provided on the pipeline between the micro-mixing heat exchanger (9) and the micro-packed bed reactor (11) and on the pipeline between the micro-packed bed reactor (11) and the gas-liquid separator (13).

5. A method for continuously catalytic hydrogenation to prepare 2,4-diaminoanisole by using the device according to claim 1, characterized in that: The catalyst Pd(OH)2 / C is filled in the micro-packed bed reactor of the device described in claim 1; the air in the device is replaced with nitrogen, and then reaction materials are added. The reaction materials and hydrogen react in the presence of nitrogen at 25-125 °C and a pressure of 1.0-3.0 MPa to prepare 2,4-diaminoanisole.

6. The method according to claim 5, characterized in that: The reaction materials are 2,4-dinitroanisole dissolved in an organic solvent. Among them, the final concentration of 2,4-dinitroanisole in the reaction materials is 0.2-0.6 mol / L; the organic solvent is tetrahydrofuran or ethyl acetate; In the Pd(OH)2 / C catalyst, the proportion of Pd(OH)2 is 7%, the carrier is spherical activated carbon with an average particle size of 0.6 mm, and the specific surface area of the catalyst is not less than 800 m 2 / g.

7. The method according to claim 5, characterized in that: The reaction materials are added to the reactor at a flow rate of 0.4-1.6 ml / min; hydrogen is added to the reactor at a flow rate of 40-70 ml / min.

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