Method and device for generating 3-pentenenitrile through hydrocyanation of 1, 3-butadiene

Abstract

The invention relates to a method and a device for generating 3-pentenenitrile through hydrocyanation of 1, 3-butadiene. The device comprises a reaction area and a discharge port located below the reaction area, and the reaction area sequentially comprises an upper portion, a lower portion, a lower portion and a material inlet from top to bottom, a middle upper part in which a plug flow reaction is performed; a middle lower part in which a circulation flow reaction is carried out; and a lower portion in which a plug flow reaction is performed. According to the device and the method provided by the invention, the conversion rate of hydrogen cyanide can be effectively improved, no residue exists, and the generation amount and the accumulation amount of a deactivated catalyst are effectively inhibited, so that the stability of a reaction system is improved, the equipment investment is saved, and the generation benefit is improved.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a method and apparatus for the hydrocyanation of 1,3-butadiene to produce 3-pentenonitrile. Background Technology

[0002] Hexamethylenediamine, the main raw material for polyamide production, is usually produced from adiponitrile, which is obtained by hydrocyanation of 1,3-butadiene with hydrogen cyanide. A catalyst is required in the preparation of adiponitrile; a typical catalyst is a nickel(O)-phosphorus complex.

[0003] Nickel(0) reacts with hydrogen cyanide to form a salt of nickel(II), which is unavoidable in the hydrocyanation of 1,3-butadiene. Furthermore, the salt of nickel(II) is insoluble in the reaction system, which is the main reason for catalyst deactivation.

[0004] Existing production technologies have several problems. While achieving high conversion rates of 1,3-butadiene, residual hydrogen cyanide in the hydrocyanation reactor necessitates subsequent hydrogen cyanide removal, increasing process complexity and equipment investment. External heat exchangers are used for heat removal, but insoluble substances from catalyst deactivation accumulate in the heat exchange lines over time, leading to reduced heat exchange efficiency and line blockage. Furthermore, the use of multiple reactors in series during the hydrocyanation stage, along with the connecting pipelines between reactors and the control system, increases the deposition of insoluble substances from the deactivated catalyst, further increasing the probability of line blockage.

[0005] For example, patent CN1914155B discloses a method for the hydrocyanation of butadiene, employing a series-connected loop reactor. This loop reactor includes an external pump circulation system, nozzles for driving the internal circulation, and an external heat exchanger. While this reduces the rate of catalyst deactivation to some extent, it still does not adequately solve the aforementioned technical problems. Summary of the Invention

[0006] Technical Purpose

[0007] In view of the problems existing in the prior art, one of the technical objectives of the present invention is to provide an apparatus for the hydrocyanation of 1,3-butadiene to produce 3-pentenonitrile. This apparatus can effectively control the residual hydrogen cyanide in the discharge and control the deactivation and deposition of the catalyst while ensuring a high conversion rate of 1,3-butadiene.

[0008] Another technical objective of the present invention is to provide a method for hydrocyanation of 1,3-butadiene using the above-described apparatus.

[0009] Technical solution

[0010] A first aspect of the present invention provides an apparatus for the hydrocyanation of 1,3-butadiene to produce 3-pentenonitrile, the apparatus comprising a vertical reactor 1, the reactor comprising:

[0011] Reaction zone: and

[0012] The discharge port N10 is located below the reaction zone and at the bottom of the reactor.

[0013] The reaction zone comprises four parts from top to bottom: (i)-(iv):

[0014] (i) The upper part in which the circulating flow reaction takes place:

[0015] The following units are provided inside the upper part:

[0016] Guide tube 2,

[0017] The vertical heat exchange tube 3 is installed between the guide tube wall and the outer wall of the reactor.

[0018] Injector 4 is located below the guide tube 2.

[0019] The premixer 5 is located below the riser heat exchanger 3.

[0020] The reactor 1, the guide tube 2, and the ejector 4 are arranged coaxially.

[0021] The following material inlets and outlets are provided on the upper outer wall:

[0022] 1,3-Butadiene feed inlet N1,

[0023] Hydrogen cyanide feed inlet N2,

[0024] Catalyst inlet N3,

[0025] The circulating material inlet N4, and

[0026] Circulating material outlet N5,

[0027] Among them, the 1,3-butadiene feed inlet N1 and the hydrogen cyanide feed inlet N2 are connected to the premixer 5 through pipelines, the outlet of the premixer 5 is connected to the inlet of the injector 4 through pipelines, the circulating material inlet N4 is connected to the inlet of the injector 4 through pipelines, and the catalyst inlet N3 is connected to the pipeline from the circulating material inlet N4 to the inlet of the injector 4 through pipelines.

[0028] The following units are provided on the exterior of the upper part:

[0029] Circulation pump P1 includes a circulation pump inlet and a circulation pump outlet.

[0030] The circulating pump inlet and the circulating material outlet N5 are connected by a pipeline, and the circulating pump outlet and the circulating material inlet N4 are connected by a pipeline.

[0031] (ii) The upper-middle part in which the plug flow reaction takes place;

[0032] (iii) The lower part in which the circulating flow reaction takes place:

[0033] The following units are provided inside the lower middle part:

[0034] Guide tube 6,

[0035] The vertical heat exchange tube 7 is installed between the guide tube wall and the outer wall of the reactor.

[0036] Injector 8 is located below the guide tube 6.

[0037] The premixer 9 is located below the riser heat exchanger 7.

[0038] The reactor 1, the guide tube 6, and the ejector 8 are arranged coaxially.

[0039] The following material inlet / outlet is provided on the outer wall of the lower middle part:

[0040] Diluent inlet N6,

[0041] Hydrogen cyanide feed inlet N7,

[0042] Circulating material inlet N8,

[0043] Circulating material outlet N9,

[0044] Among them, the diluent feed inlet N6 and the hydrogen cyanide feed inlet N7 are connected to the premixer 9 through pipelines, the outlet of the premixer 9 is connected to the inlet of the injector 8 through pipelines, and the circulating material inlet N8 is connected to the inlet of the injector 8 through pipelines.

[0045] The following units are provided on the exterior of the lower middle section:

[0046] Circulation pump P2 includes a circulation pump inlet and a circulation pump outlet.

[0047] The circulating pump inlet and the circulating material outlet N9 are connected by a pipeline, and the circulating pump outlet and the circulating material inlet N8 are connected by a pipeline.

[0048] (iv) The lower part in which the plug flow reaction takes place.

[0049] In a specific implementation, if the circulating flow reaction and the plug flow reaction are combined as a group, the reaction zone includes two or more such combinations, and the specific number of combinations is determined based on the main reaction and catalyst deactivation kinetics.

[0050] In a specific implementation, with the total height of the reaction zone as 1, the upper part is located at a height of 2 / 3 to 1, the upper middle part is located at a height of 1 / 2 to 4 / 6, the lower middle part is located at a height of 1 / 6 to 1 / 2, and the lower part is located at a height of 0 to 1 / 6.

[0051] In a specific embodiment, the discharge port N10 is funnel-shaped.

[0052] On the other hand, the present invention provides a method for hydrocyanation of 1,3-butadiene using the above-described apparatus, the method comprising the following reaction process:

[0053] The circulating reaction in the upper part:

[0054] Liquid 1,3-butadiene and liquid hydrogen cyanide, fed from 1,3-butadiene inlet N1 and hydrogen cyanide inlet N2 respectively, are premixed in premixer 5 at a molar ratio of 1:0.1 to 0.6 to form premixed material. The material in the reactor is drawn out by circulation pump P1 through circulation material outlet N5 to form external circulation material. The external circulation material returns to the ejector 4 set in the reactor through circulation material inlet N4. Before entering the ejector, it is mixed with the catalyst fed through catalyst inlet N3 and the premixed material in sequence. It is then sprayed out through ejector 4. The sprayed material passes through the internal channel of guide tube 2 and then enters the annular channel formed by the outer wall of guide tube 2 and the wall of reactor 1. Then it returns to the internal channel of guide tube 2 at the outlet of the annular channel to form internal circulation. Part of the material enters circulation pump P1 to undergo external circulation.

[0055] Plug flow reaction in the upper and middle part:

[0056] The circulating reactants in the upper part are transferred to the middle and upper part and enter the plug flow stage. No new hydrogen cyanide is introduced here, so that the residual hydrogen cyanide is completely converted from the time it enters the plug flow stage until it leaves.

[0057] The recirculating flow reaction in the lower middle section:

[0058] Material leaving the plug flow stage is transferred to the lower and middle sections, entering the circulating flow reaction stage. In the lower and middle sections, diluent and hydrogen cyanide are introduced through diluent inlet N6 and hydrogen cyanide inlet N7, respectively. The two are premixed by premixer 9. The molar ratio of hydrogen cyanide to 1,3-butadiene (introduced in the upper section) added in the lower and middle sections is 0.2–0.9:1, and the mass ratio of hydrogen cyanide to diluent is 0.2–1:1.

[0059] Hydrogen cyanide diluted by the diluent reacts with the material from the upstream horizontal mass transfer in the reactor during internal circulation. The material in the reactor is drawn out by the circulation pump P2 through the circulation material outlet N9 to form external circulation material. The external circulation material returns to the ejector 8 through the circulation material inlet N8. Before entering the ejector 8, it mixes with the hydrogen cyanide diluted by the diluent and is then ejected through the ejector. The ejected material passes through the internal channel of the guide tube 6 and then enters the annular channel formed by the outer wall of the guide tube 6 and the wall of the reactor 1. Then, it returns to the internal channel of the guide tube 6 at the outlet of the annular channel to form internal circulation. Part of the material enters the circulation pump P2 for external circulation.

[0060] The plug flow reaction in the lower part:

[0061] The circulating reactants from the middle and lower sections undergo mass transfer to the lower section, entering the plug flow stage. No hydrogen cyanide is introduced here, ensuring that any residual hydrogen cyanide is completely converted from the moment it enters the plug flow stage until it leaves.

[0062] Product discharge:

[0063] The product from the lower part is discharged through the discharge port N10, wherein the product does not contain hydrogen cyanide and contains deactivated catalyst at a mass content of less than 12 ppm.

[0064] In a specific implementation, the mass ratio of the external circulating material to the total feed amount in the upper part and the middle and lower parts are independently 5 to 30:1, where the total feed amount refers to the sum of the feed amount in the upper part and the feed amount in the middle and lower parts.

[0065] In a specific embodiment, the material temperature controlled by the vertical heat exchange tube in the upper and lower parts is 50-90°C, for example, 65-80°C.

[0066] In a specific embodiment, in the lower part, the diluent is any substance that does not participate in the 1,3-butadiene hydrocyanation reaction, such as butene or cyclohexane.

[0067] In a specific implementation, the method may include two or more combinations of circulating flow reaction and plug flow reaction.

[0068] In this application, there are no particular limitations on the type of catalyst used in the hydrocyanation of 1,3-butadiene. It can be any conventional catalyst used in the prior art for the hydrocyanation of 1,3-butadiene, such as those disclosed in CN1914155B. Specifically, the catalyst that can be used in this application is a mixture of nickel (O) and tri-m- / p-toluene phosphite in a molar ratio of 1:4 to 10, with a molar ratio of catalyst to 1,3-butadiene of 0.005 to 0.2:1.

[0069] To further explain, the amount of insoluble matter produced by catalyst deactivation is determined by its kinetics, that is,

[0070] M = F(C HCN C Ni(0) ,T,t),

[0071] M: Amount of insoluble deactivated catalyst

[0072] C HCN Hydrogen cyanide concentration

[0073] C Ni(0) Nickel (0) concentration

[0074] T: Temperature

[0075] T: Duration of stay

[0076] Beneficial effects

[0077] This application proposes a novel method and apparatus for the hydrocyanation of 1,3-butadiene. The method is carried out in a reactor, which effectively improves the conversion rate of hydrogen cyanide, eliminates residues, and effectively suppresses the generation and accumulation of deactivated catalyst, thereby improving the stability of the reaction system, saving equipment investment, and increasing production efficiency.

[0078] Furthermore, in this application, a dilution process is added before the hydrogen cyanide comes into contact with the catalyst. Specifically, the hydrogen cyanide is diluted with 1,3-butadiene upon initial introduction into the reactor, and with butene upon subsequent introduction. The catalyst is diluted with the circulating material. An injector is used to shorten the contact time between the newly introduced hydrogen cyanide and the catalyst, and the hydrogen cyanide is further diluted by the internal circulating material after injection. By employing the above methods, this application overcomes the problem in the prior art where hydrogen cyanide comes into contact with the catalyst upon introduction into the reaction system, resulting in a localized high concentration at the introduction point. This effectively reduces the concentration of hydrogen cyanide and the concentration of the catalyst when they come into contact, shortens the residence time, and thus effectively reduces the residual hydrogen cyanide in the reactor effluent and effectively inhibits catalyst deactivation. Attached Figure Description

[0079] Figure 1 The diagram shows a schematic of the apparatus used in this application for the hydrocyanation of 1,3-butadiene to produce 3-pentenonitrile.

[0080] Figure Labels

[0081] 1 – Vertical reactor

[0082] 2, 6 – Flow Guide

[0083] 3, 7 – Riser heat exchange tubes

[0084] 4, 8 – Injectors

[0085] 5, 9 – Premixer

[0086] N1–1,3-Butadiene feed inlet

[0087] N2, N7 – Hydrogen cyanide feed inlet

[0088] N3 – Catalyst feed inlet

[0089] N4, N8 – Circulating material inlet

[0090] N5, N9 – Circulating material outlet

[0091] N6 – Diluent Inlet

[0092] N10 – Discharge Port

[0093] P1, P2 – Circulation pumps Detailed Implementation

[0094] The technical solutions of this application are described in detail below through specific embodiments to enable those skilled in the art to better understand this application; however, these embodiments are not intended to limit the scope of this application.

[0095] The device of this application is as follows Figure 1 As shown. Specifically, the device includes:

[0096] Reactor 1 is a vertical reactor consisting of four reaction zones: upper, upper middle, lower middle, and lower, as well as a discharge port.

[0097] upper part

[0098] The reactor has an upper internal guide tube 2, with a vertical heat exchange tube 3 installed between the guide tube wall and the outer wall of the reactor. An ejector 4 is located below the guide tube. The reactor 1, guide tube 2, and ejector 4 are coaxially arranged. A premixer 5 is also installed inside the upper part. The outlet of the premixer 5 is connected to the inlet of the ejector 4 via a pipeline. The upper outer wall has a 1,3-butadiene feed inlet N1, a hydrogen cyanide feed inlet N2, a catalyst feed inlet N3, a circulating material inlet N4, and a circulating material outlet N5. The 1,3-butadiene feed inlet N1 and the hydrogen cyanide feed inlet N2 are connected to the premixer 5 via pipelines. The circulating material inlet N4 is connected to the inlet of the ejector 4 via a pipeline. The catalyst inlet N3 is connected to the pipeline from the circulating material inlet N4 to the inlet of the ejector 4. The reactants undergo a circulating flow reaction in the upper part.

[0099] The upper external circulation pump P1 includes a circulation pump inlet and a circulation pump outlet. The circulation pump inlet is connected to the circulating material outlet N5 through a pipeline, and the circulation pump outlet is connected to the circulating material inlet N4. It is used to provide driving force for the circulation of materials in the upper part of the reactor.

[0100] middle and upper part

[0101] The material undergoes plug flow motion and plug flow reaction in the upper and middle parts.

[0102] middle and lower part

[0103] The reactor 1 has an internal guide tube 6 in the lower middle section, with a vertical heat exchange tube 7 installed between the guide tube wall and the outer wall of the reactor. An ejector 8 is installed below the guide tube. The reactor 1, guide tube 6, and ejector 8 are coaxially arranged. A premixer 9 is also installed inside the lower middle section, and the outlet of the premixer 9 is connected to the inlet of the ejector 8 through a pipeline. The outer wall of the lower middle section has a diluent feed inlet N6, a hydrogen cyanide feed inlet N7, a circulating material inlet N8, and a circulating material outlet N9. The diluent feed inlet N6 and the hydrogen cyanide feed inlet N7 are connected to the premixer 9 through pipelines, and the circulating material inlet N8 is connected to the inlet of the ejector 8 through a pipeline. The reactants undergo a circulating flow reaction in the lower middle section.

[0104] The lower-middle external circulation pump P2 includes a circulation pump inlet and a circulation pump outlet. The circulation pump inlet is connected to the circulating material outlet N9 via a pipeline, and the circulation pump outlet is connected to the circulating material inlet N8. It is used to provide driving force for the circulation of materials in the upper part of the reactor.

[0105] lower part

[0106] The material moves in a plug flow motion at the bottom and undergoes a plug flow reaction.

[0107] discharge port

[0108] A discharge port N10 is provided at the lower end.

[0109] Example 1

[0110] Reactor structural dimensions: inner diameter 250mm, height 3000mm; upper part height 1000mm, guide tube inner diameter 80mm, height 800mm; upper middle part height 500mm; lower middle part height 1000mm, guide tube inner diameter 80mm, height 800mm; lower part height 500mm.

[0111] Top feed: 10 kmol of 1,3-butadiene, 4 kmol of hydrogen cyanide, 1 kmol of catalyst; external circulation: 150 kmol of catalyst is drawn out and circulated within the reactor. The material temperature is controlled at 76°C.

[0112] Lower and middle feed: 5 kmol of hydrogen cyanide and 5 kmol of butene, with an external circulation rate of 200 kmol, and the material temperature is controlled at 76℃.

[0113] Running time: 72 hours.

[0114] The chromatographic analysis of the product showed that the hydrogen cyanide conversion rate was 100%, the hydrogen cyanide content was 0 ppm, and the deactivated catalyst content was 10 ppm.

[0115] Example 2

[0116] The reactor structure and feed rate are the same as in Example 1.

[0117] The runtime is 720 hours.

[0118] Chromatographic analysis of the product showed that the hydrogen cyanide content was 0 ppm and the deactivated catalyst content was 11 ppm.

[0119] Example 3

[0120] The reactor structure is the same as in Example 1.

[0121] Top feed: 6 kmol of 1,3-butadiene, 2.4 kmol of hydrogen cyanide, and 0.3 kmol of catalyst. An external circulation flow of 90 kmol is generated within the reactor. The material temperature is controlled at 65°C.

[0122] Lower feed: 3 kmol of hydrogen cyanide, 4 kmol of butene, with an external circulation rate of 130 kmol.

[0123] The runtime is 72 hours.

[0124] The chromatographic analysis of the product showed that the hydrogen cyanide content was 0 ppm and the deactivated catalyst content was 9.5 ppm.

[0125] Example 4

[0126] The reactor structure is the same as in Example 3.

[0127] Top feed: 6 kmol of 1,3-butadiene, 2.4 kmol of hydrogen cyanide, and 0.3 kmol of catalyst. An external circulation flow of 90 kmol is generated within the reactor. The material temperature is controlled at 65°C.

[0128] Lower feed: 3 kmol of hydrogen cyanide, 4 kmol of butene, with an external circulation rate of 130 kmol.

[0129] Running time: 720 hours.

[0130] The chromatographic analysis of the product showed that the hydrogen cyanide content was 0 ppm and the deactivated catalyst content was 11 ppm.

[0131] As can be seen from the results of the above embodiments, the method and apparatus designed in this application effectively control the residual hydrogen cyanide in the reactor effluent during the hydrocyanation of 1,3-butadiene, and effectively control the generation of deactivated catalyst.

Claims

1. An apparatus for the hydrocyanation of 1,3-butadiene to produce 3-pentenonitrile, said apparatus comprising a vertical reactor (1) comprising: Reaction zone: and The discharge port (N10) is located below the reaction zone and at the bottom of the reactor. The reaction zone comprises four parts from top to bottom: (i)-(iv): (i) The upper part in which the circulating flow reaction takes place: The following units are provided inside the upper part: Guide tube (2), The vertical heat exchange tube (3) is installed between the guide tube wall and the outer wall of the reactor. The injector (4) is located below the guide tube (2). The premixer (5) is located below the riser heat exchanger (3). The reactor (1), the guide tube (2), and the ejector (4) are coaxially arranged. The following material inlets and outlets are provided on the upper outer wall: 1,3-Butadiene feed inlet (N1), Hydrogen cyanide feed inlet (N2), Catalyst feed inlet (N3), Circulating material inlet (N4), and Circulating material outlet (N5), Among them, the 1,3-butadiene feed inlet (N1) and the hydrogen cyanide feed inlet (N2) are connected to the premixer (5) through pipelines, the outlet of the premixer (5) is connected to the inlet of the injector (4) through pipelines, the circulating material inlet (N4) is connected to the inlet of the injector (4) through pipelines, and the catalyst inlet (N3) is connected to the pipeline from the circulating material inlet (N4) to the inlet of the injector (4) through pipelines; The following units are provided on the exterior of the upper part: The circulating pump (P1) includes a circulating pump inlet and a circulating pump outlet. The circulating pump inlet is connected to the circulating material outlet (N5) via a pipeline, and the circulating pump outlet is connected to the circulating material inlet (N4) via a pipeline. (ii) The upper-middle part in which the plug flow reaction takes place; (iii) The lower part in which the circulating flow reaction takes place: The following units are provided inside the lower middle part: Guide tube (6), The vertical heat exchange tube (7) is installed between the guide tube wall and the outer wall of the reactor. The injector (8) is located below the guide tube (6). The premixer (9) is located below the riser heat exchanger (7). The reactor (1), the guide tube (6), and the ejector (8) are coaxially arranged. The following material inlet / outlet is provided on the outer wall of the lower middle part: Diluent inlet (N6), Hydrogen cyanide feed inlet (N7), Circulating material inlet (N8), Circulating material outlet (N9), Among them, the diluent feed inlet (N6) and the hydrogen cyanide feed inlet (N7) are connected to the premixer (9) through pipelines, the outlet of the premixer (9) is connected to the inlet of the injector (8) through pipelines, and the circulating material inlet (N8) is connected to the inlet of the injector (8) through pipelines. The following units are provided on the exterior of the lower middle section: The circulating pump (P2) includes a circulating pump inlet and a circulating pump outlet. The circulating pump inlet is connected to the circulating material outlet (N9) via a pipeline, and the circulating pump outlet is connected to the circulating material inlet (N8) via a pipeline. (iv) The lower part in which the plug flow reaction takes place.

2. The apparatus according to claim 1, wherein, If the circulating flow reaction and the plug flow reaction are combined as a single combination, the reaction zone includes two or more such combinations.

3. The apparatus according to claim 1, wherein, With the total height of the reaction zone as 1, the upper part is located at 2 / 3 to 1 of the height, the upper middle part is located at 1 / 2 to 4 / 6 of the height, the lower middle part is located at 1 / 6 to 1 / 2 of the height, and the lower part is located at 0 to 1 / 6 of the height.

4. The apparatus according to claim 1, wherein, The discharge port (N10) is funnel-shaped.

5. A method for hydrocyanation of 1,3-butadiene using the apparatus as described in claim 1, the method comprising the following reaction steps: The circulating reaction in the upper part: Liquid 1,3-butadiene and liquid hydrogen cyanide, fed from the 1,3-butadiene feed inlet (N1) and hydrogen cyanide feed inlet (N2) respectively, are premixed in the premixer (5) at a molar ratio of 1:0.1 to 0.6 to form a premixed material. The material in the reactor is drawn out by the circulation pump (P1) through the circulation material outlet (N5) to form an external circulation material. The external circulation material returns to the ejector (4) set in the reactor through the circulation material inlet (N4). Before entering the ejector, it is mixed with the catalyst fed through the catalyst feed inlet (N3) and the premixed material in sequence. It is then sprayed out through the ejector (4). The sprayed material passes through the internal channel of the guide tube (2) and then enters the annular channel formed by the outer wall of the guide tube (2) and the reactor (1) wall. Then it returns to the internal channel of the guide tube (2) at the outlet of the annular channel to form an internal circulation. Part of the material enters the circulation pump (P1) to form an external circulation. Plug flow reaction in the upper and middle part: The circulating reactants in the upper part are transferred to the middle and upper part and enter the plug flow stage. No new hydrogen cyanide is introduced here, so that the residual hydrogen cyanide is completely converted from the time it enters the plug flow stage until it leaves. The recirculating flow reaction in the lower middle section: Material leaving the plug flow stage is transferred to the middle and lower section and enters the circulating flow reaction stage. In the middle and lower section, diluent and hydrogen cyanide are introduced through the diluent inlet (N6) and hydrogen cyanide inlet (N7), respectively, and premixed by the premixer (9). The molar ratio of hydrogen cyanide to 1,3-butadiene added in the lower part is 0.2–0.9:1, and the mass ratio of hydrogen cyanide to diluent is 0.2–1:

1. Hydrogen cyanide diluted by the diluent reacts with the material from the upstream horizontal mass transfer in the reactor in an internal circulation. The material in the reactor is drawn out by the circulation pump (P2) through the circulation material outlet (N9) to form an external circulation material. The external circulation material returns to the ejector (8) through the circulation material inlet (N8). Before entering the ejector (8), it is mixed with the hydrogen cyanide diluted by the diluent and then ejected through the ejector. The ejected material passes through the internal channel of the guide tube (6) and then enters the annular channel formed by the outer wall of the guide tube (6) and the reactor (1). Then it returns to the internal channel of the guide tube (6) at the outlet of the annular channel to form an internal circulation. Part of the material enters the circulation pump (P2) to form an external circulation. The plug flow reaction in the lower part: The circulating reactants from the middle and lower sections undergo mass transfer to the lower section, entering the plug flow stage. No hydrogen cyanide is introduced here, ensuring that any residual hydrogen cyanide is completely converted from the moment it enters the plug flow stage until it leaves. Product discharge: The product from the lower part is discharged through the outlet (N10), wherein the product does not contain hydrogen cyanide and contains deactivated catalyst at a mass content of less than 12 ppm.

6. The method according to claim 5, wherein, In the upper part and the middle and lower parts, the mass ratio of the external circulating material to the total feed is independently 5 to 30:1, where the total feed refers to the sum of the feed in the upper part and the feed in the middle and lower parts.

7. The method according to claim 5, wherein, In the upper and lower middle sections, the material temperature controlled by the vertical heat exchange tubes is 50–90°C, for example, 65–80°C.

8. The method according to claim 5, wherein, In the lower middle section, the diluent is any substance that does not participate in the 1,3-butadiene hydrocyanation reaction.

9. The method according to claim 5, wherein, In the lower middle section, the diluent is selected from butene and cyclohexane.

10. The method according to claim 5, wherein, The method combines circulating flow reaction and plug flow reaction as a combination, and includes two or more such combinations.

11. The method according to claim 5, wherein, The catalyst is a mixture of nickel (0) and tri-m- / p-toluene phosphite in a molar ratio of 1:4 to 10, and the molar ratio of the catalyst to 1,3-butadiene is 0.005 to 0.2:1.

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