Gas distributor, gas-solids fluidized reactor and applications and methods

Abstract

The application discloses a gas distributor, a gas-solid fluidized reactor, an application and a method. The gas distributor comprises a plurality of gas distribution units. The plurality of gas distribution units are arranged at intervals along an H direction and form a plurality of H-direction intervals L between two adjacent gas distribution units. The plurality of H-direction intervals L are equal or sequentially increase along the H direction. Each gas distribution unit comprises a branch pipe with a gas inlet. A plurality of branch pipes are communicated with the branch pipe. A plurality of nozzles are arranged on the branch pipe and each branch pipe. The application can reduce the consumption of reaction raw materials, improve product yield, and has a simple process and is easy to realize industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical raw material preparation technology, specifically to a gas distributor, a gas-solid fluidization reactor, and their applications and methods. Background Technology

[0002] Isophthalonitrile (IPN) is a white needle-like crystal, slightly soluble in hot water, but soluble in hot ethanol, ether, benzene, chloroform, etc. It has a melting point of 163–165℃ and a boiling point of 288℃, and is the most in-demand aromatic nitrile. Its main uses are twofold: first, tetrachloroisophthalonitrile (chlorothalonil), produced by chlorination, is a highly effective and low-toxicity bactericide; second, m-phenylenediamine, produced by hydrogenation, is a high-performance resin curing agent and a raw material for polyurethane and nylon resins. The fluidized bed gas-phase ammonia oxidation method using fine-particle catalysts is currently the most advanced method for producing isophthalonitrile. However, in existing technologies, to improve the conversion rate and selectivity of the reaction, large amounts of ammonia and oxygen are often introduced during the production process. This exacerbates side reactions such as ammonia combustion and deep oxidation, generating large amounts of N2 and COx, wasting raw materials, and reducing the purity of IPN in the product, creating pressure for subsequent separation and hindering its application in the production of high-end chemicals. Summary of the Invention

[0003] The present invention aims to provide a gas distributor, a gas-solid fluidized bed reactor, and its applications and methods, which have the advantages of reducing the amount of reaction raw materials (e.g., the reaction ammonia ratio), increasing product yield, and having a simple process that is easy to implement in industrial production.

[0004] To achieve the above objectives, the present invention provides a gas distributor, the gas distributor comprising:

[0005] Multiple air distribution units are arranged at intervals along the H direction and form multiple H-direction spacings L between adjacent air distribution units. The multiple H-direction spacings L are equal or increase sequentially along the H direction.

[0006] Each of the air distribution units includes a branch pipe with an air inlet, the branch pipe being connected to multiple branch pipes, and multiple nozzles being arranged on the branch pipe and each of the branch pipes.

[0007] A second aspect of the present invention provides a gas-solid fluidized bed reactor, wherein a second gas distributor connected to a second gas phase inlet is provided at the bottom of the cavity of the gas-solid fluidized bed reactor, and a first gas distributor is provided above the second gas distributor. The first gas distributor is the gas distributor described in the present invention, and the inlet of the branch pipe of the first gas distributor is connected to the first gas phase inlet.

[0008] Preferably, the bottom opening of the main pipe of the first gas distributor is connected to the first gas phase inlet.

[0009] The application of the gas-solid fluidized bed reactor of the present invention in the ammonia oxidation reaction of aromatics.

[0010] This invention provides a method for the ammoxidation of aromatic hydrocarbons, the method employing the gas-solid fluidized bed reactor described in this invention, and comprising:

[0011] 1) A mixed feedstock containing ammonia and aromatics is introduced into the second gas phase inlet, dispersed into the cavity by the second gas distributor, and comes into contact with the oxygen-containing gas carried in the catalyst to generate an initial aromatic nitrile stream.

[0012] 2) Oxygen-containing gas is introduced into the first gas phase inlet, and after passing through the first gas distributor, it is dispersed along the axial direction of the cavity and comes into contact with the initial aromatic nitrile stream to generate the later aromatic nitrile stream.

[0013] Through the above technical solution, the gas distributor of the present invention can control the content of gaseous materials in different reaction stages, improve the yield of target products, and further solve the problems of low product purity caused by excessive ammonia ratio and air ratio required for ammonia oxidation, low raw material utilization efficiency, and numerous side reactions in the prior art. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the gas-solid fluidized bed reactor according to a specific implementation method;

[0015] Figure 2 This is a schematic diagram of the annular partition in the post-reaction section;

[0016] Figure 3 yes Figure 1 Schematic diagram of the gas distributor in the middle;

[0017] Figure 4 This is a schematic diagram of the structure of an air distribution unit;

[0018] Figure 5 This is a schematic diagram of another type of air distribution unit;

[0019] Figure 6 This is a schematic diagram of the radial cross-section of a branch pipe or sub-branch pipe;

[0020] Figure 7 These are schematic diagrams of the air distributor and aromatic / ammonia distributor in the prior art, as shown in Comparative Examples 1 and 2.

[0021] Explanation of reference numerals in the attached figures

[0022] 1. Pre-reaction section; 2. Post-reaction section; 3. Inner circulation zone; 4. Annular baffle; 5. Columnar lifting section; 6. Gas-solid separation section; 7. Cyclone separator; 8. External circulation pipe; 9. Catalyst regenerator; 10. Second gas distributor; 11. First gas distributor; 12. Second gas phase inlet; 13. First gas phase inlet; 14. Air inlet; 15. Outlet; 401. Through hole; 402. Annular shell; 1101. Main pipe; 1102. Branch pipe; 1103. Sub-branch pipe; 1104. Nozzle. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "left," and "right" generally refer to the upper, lower, left, and right as shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0026] The first aspect of this invention discloses a gas distributor, such as... Figure 1 or Figure 3 As shown, the gas distributor includes:

[0027] Multiple air distribution units are arranged at intervals along the H direction, and multiple H-direction spacings L are formed between two adjacent air distribution units. The multiple H-direction spacings L are equal or increase sequentially along the H direction.

[0028] Each air distribution unit includes a branch pipe 1102 with an air inlet, and multiple branch pipes 1103 are connected to the branch pipe 1102. Multiple nozzles 1104 are arranged on the branch pipe 1102 and each branch pipe 1103.

[0029] The gas distributor of the present invention can control the content of gaseous materials in different reaction stages and improve the yield of the target product.

[0030] In some embodiments of the present invention, along the H direction, multiple H-direction spacings L are sequentially named L1...L1. n , where L n :L n-1 =1 to 1.5.

[0031] In some embodiments of the present invention, the total orifice ratio of the gas distributor is 0.1% to 10%.

[0032] In some embodiments of the present invention, a plurality of nozzles 1104 are arranged at intervals along the length of each branch pipe 1102, and two adjacent nozzles 1104 on the same branch pipe 1102 are arranged symmetrically about the axis of the branch pipe 1102, and as shown in the figure. Figure 6 The figure shows an included angle γ;

[0033] Multiple nozzles 1104 are arranged at intervals along the length of each branch pipe 1103, and two adjacent nozzles 1104 on the same branch pipe 1103 are arranged symmetrically about the axis of the branch pipe 1103, and so on. Figure 6 The figure shows an included angle γ.

[0034] In some embodiments of the present invention, γ is preferably 30 to 120°.

[0035] In some embodiments of the present invention, the gas distributor further includes a main pipe 1101 arranged in the H direction, the bottom opening of the main pipe 1101 for air intake, and in each gas distribution unit, multiple branch pipes 1102 are provided, the multiple branch pipes 1102 are arranged radially on the side of the main pipe 1101 and connected to the main pipe 1101.

[0036] In some embodiments of the present invention, preferably, each gas distribution unit has 4 to 16 branch pipes 1102, and the angle α between the axis of each branch pipe 1102 and the axis of the main pipe 1101 is 30 to 90°, more preferably α is 30 to 75°. Based on the foregoing disclosure, the present invention employs the above-mentioned preferred methods to control the oxygen content at different reaction stages in the ammonia oxidation reaction, suppress deep oxidation, and has the advantages of improving the quality of gas-solid fluidization and avoiding uneven reaction and localized overheating of the bed.

[0037] In some embodiments of the present invention, in each air distribution unit, a plurality of branch pipes 1103 are distributed on both sides of the branch pipe 1102.

[0038] In other embodiments of the present invention, a plurality of branch pipes 1103 are radially distributed on the side of the branch pipe 1102.

[0039] In other embodiments of the invention, the branch pipe 1103 is annular (e.g., Figure 4 Circular or Figure 5 (A polygon), with multiple annular branch pipes 1103 arranged concentrically, each branch pipe 1102 extending along the radial direction of the branch pipe 1103 and communicating with the annular branch pipe, the inner end of the branch pipe 1102 communicating with the side of the main pipe 1101, and the outer end being closed.

[0040] The second aspect of this invention discloses a gas-solid fluidized bed reactor, such as... Figure 1 The gas-solid fluidized bed reactor shown has a second gas distributor 10 connected to a second gas phase inlet 12 at the bottom of its cavity. A first gas distributor 11 is positioned above the second gas distributor 10. The first gas distributor 11 uses the gas distributor of this invention. The inlet of the branch pipe 1102 of the first gas distributor 11 is connected to the first gas phase inlet 13; preferably, the bottom opening of the main pipe 1101 of the first gas distributor 11 is connected to the first gas phase inlet 13. In this invention, there are no special requirements for the second gas distributor 10; a conventional gas distributor used in existing technologies, such as those used in ammonia oxidation reactions, can be used.

[0041] In some embodiments of the present invention, the cavity comprises, from bottom to top, a pre-reaction section 1, a post-reaction section 2, and a gas-solid separation section 6 that are interconnected. A second gas distributor 10 is installed in the pre-reaction section 1, and a first gas distributor 11 is installed in the post-reaction section 2.

[0042] In some embodiments of the present invention, a rapid lifting structure is provided in the cavity; preferably, the rapid lifting structure includes an upwardly tapering constriction at the outlet end of the post-reaction section 2, the smaller end of which extends into the gas-solid separation section to form a cylindrical lifting section 5, the cross-sectional area of ​​which is 1 / 5 to 4 / 5 of the cross-sectional area of ​​the post-reaction section 2. This accelerates the linear velocity of the upward movement of gas and solid, thus avoiding backmixing and shortening the residence time, and preventing the reduction in product yield and purity caused by deep oxidation in the oxidation reaction.

[0043] In some embodiments of the present invention, the cross-sectional area of ​​the cavity is such that the gas-solid separation section 6 > the post-reaction section 2 = the pre-reaction section 1. Heat exchange components, such as heat exchange tubes connecting heat exchangers, are provided in the pre-reaction section and the post-reaction section. A cyclone separator 7 is provided in the cavity of the gas-solid separation section to separate the later aromatic nitrile stream from the post-reaction section and discharge it from the gas-solid fluidized reactor through the outlet 15. The top of the columnar lifting section 5 is provided with downwardly curved arc baffles at intervals.

[0044] In some embodiments of the present invention, an annular baffle 4 is provided in the post-reaction section 2, and a first gas distributor 11 is provided in the area defined by the annular baffle 4. The annular gap between the annular baffle 4 and the cavity wall of the post-reaction section 2 forms an inner circulation zone 3.

[0045] To enhance the internal circulation within the cavity, in some embodiments of the present invention, it is preferable that a plurality of through holes 401 are provided on the side wall of the annular partition 4, through which solid particles in the inner defined area of ​​the annular partition 4 can flow into the internal circulation area 3.

[0046] In some embodiments of the present invention, such as Figures 1-2As shown, the bottom end of the preferred annular partition 4 is connected to an annular housing 402, which is formed as an upwardly tapering bottom opening, and the angle β between the side wall of the annular housing 402 and the side wall of the annular partition 4 is 30 to 60°.

[0047] In some embodiments of the present invention, the cross-sectional area of ​​the inner circulation zone 3 is preferably 1 / 10 to 1 / 2 of the cross-sectional area of ​​the post-reaction section 2.

[0048] In some embodiments of the present invention, such as Figure 1 As shown, the gas-solid fluidized bed reactor is equipped with an external circulation unit, which includes a catalyst regenerator 9 and is connected to the pre-reaction section 1 and the gas-solid separation section 6. The external circulation unit is used to extract and regenerate part of the catalyst in the gas-solid separation section 6 and send it back to the pre-reaction section 1.

[0049] In some embodiments of the present invention, the external circulation unit includes an external circulation pipe 8 connecting the gas-solid separation section and the pre-reaction section. A catalyst regenerator 9 is installed on the external circulation pipe; for example, the catalyst regenerator 9 is selected from a catalyst oxygenator. The catalyst oxygenator is equipped with a waste gas discharge pipe and an air inlet 14 for oxygenating the catalyst to be generated therein. The gas-solid fluidized bed reactor of the present invention, employing a dual-circulation fluidized bed configuration combining internal and external circulation of catalyst particles, can improve product yield.

[0050] The fourth aspect of this invention discloses the application of the gas-solid fluidized bed reactor of this invention in the ammoxidation reaction of aromatic hydrocarbons.

[0051] The fifth aspect of this invention discloses a method for the ammoxidation of aromatic hydrocarbons, the method employing the gas-solid fluidized bed reactor of this invention, and comprising:

[0052] 1) A mixed feedstock containing ammonia and aromatics is introduced into the second gas phase inlet 12 and dispersed into the cavity through the second gas distributor 10 to contact the oxygen-containing gas carried in the catalyst to generate an initial aromatic nitrile stream; Step 1) mainly utilizes the oxygen carried in the catalyst for the initial reaction, which is mainly used to generate reaction intermediates and reduce CO2 generation.

[0053] 2) Oxygen-containing gas is introduced into the first gas phase inlet 13, and dispersed along the axial direction of the cavity by the first gas distributor 11, contacting the initial aromatic nitrile-containing stream to generate the later aromatic nitrile-containing stream. Step 2) mainly involves further ammonia oxidation of the intermediate product generated in step 1). In addition to providing the oxygen required for the reaction in stages along the axial direction, the first gas distributor 11 can also improve the quality of gas-solid fluidization, avoid uneven reaction and local overheating of the bed, and further suppress backmixing.

[0054] In the later stages of the post-reaction section, aromatic nitrile streams are partially transported upwards through the constriction and columnar elevation section 5, while the rest are transported downwards through the internal circulation zone 3. The solid catalyst exiting the internal circulation zone 3 participates again in the ammonia oxidation reaction in the pre-reaction section 1. The catalyst from the internal circulation carries some of the gaseous oxygen introduced in the post-reaction section 2, increasing the oxygen content in the pre-reaction section 1 to promote the reaction. In addition, the catalysts in both the internal and external circulation zones also act as heat regulators, making the operation safer.

[0055] In the later stage of upward movement, the aromatic nitrile-containing stream undergoes gas-solid separation in the gas-solid separation section 6. The solid catalyst moves downward and a portion of it is recycled and regenerated through the external circulation pipe 8 before being fed back to the pre-reaction section. The gas carries a small amount of solid particles upward and undergoes gas-solid separation again through the cyclone separator 7 located at the top of the gas-solid fluidized reactor. The gas phase product flows out through the outlet 15 at the top of the device and, after washing, filtration, dehydration, and drying, finally yields the target product, aromatic nitrile.

[0056] The catalyst particles entering circulation pipe 8 flow into the catalyst oxygenator along the pipeline. Air is introduced into the catalyst oxygenator through air inlet 14 to replenish oxygen to the reacted catalyst. The oxygenated catalyst then flows through the pipeline into the pre-reaction section at the bottom of the reactor for another ammonia oxidation reaction. The function of the catalyst oxygenator is to regenerate the catalyst that has lost lattice oxygen. The exhaust gas leaves the oxygenator and does not enter the pre-reaction section 1 with the oxygenated catalyst.

[0057] In some embodiments of the aromatic hydrocarbon ammonia oxidation of the present invention, a portion of the stream in the post-reaction section is refluxed back to the pre-reaction section 1 through the internal circulation zone 3.

[0058] In some embodiments of the aromatic hydrocarbon ammoxidation of the present invention, the total catalyst load (WWH) is 0.07–0.2 h. -1 The preferred time is 0.09–0.15 h. -1 .

[0059] In some embodiments of the aromatic hydrocarbon ammoxidation of the present invention, step 1) is carried out in the pre-reaction section 1, and the temperature of the pre-reaction section 1 is controlled at 350-410°C.

[0060] In some embodiments of the aromatic hydrocarbon ammoxidation of the present invention, step 2) is carried out in the post-reaction section 2, and the temperature of the pre-reaction section 1 is controlled at 400-450°C.

[0061] In some embodiments of the aromatic hydrocarbon ammonia oxidation of the present invention, the temperature of the columnar lifting section 5 and the inner circulation zone 3 is controlled to be 360-400°C.

[0062] In some embodiments of the aromatic ammonia oxidation of the present invention, the temperature of the catalyst oxygenator is controlled at 460–500°C.

[0063] In some embodiments of the aromatic hydrocarbon ammoxidation of the present invention, the molar ratio of the feed to the second gas distributor 10 and the first gas distributor 11 is aromatic hydrocarbon: ammonia: air = 1:3 to 8:20 to 40. In the present invention, aromatic hydrocarbons include, but are not limited to, o-xylene, m-xylene, p-xylene, or 4-nitro-o-xylene.

[0064] In some embodiments of the aromatic hydrocarbon ammonia oxidation of the present invention, the ratio of m-xylene:ammonia:air is preferably 1:4-5:25-30.

[0065] The advantages of the present invention are illustrated below through examples, but the present invention is not limited thereto.

[0066] The following examples 1-3 are in Figures 1-6 The gas-solid fluidized bed reactor shown was used in the embodiment 4-8, which were modified from Example 1. The differences have been described in each embodiment.

[0067] The gas-solid fluidized bed reactor adopts a dual-circulation fluidized bed structure that combines internal and external circulation of catalyst particles. Specifically, the reactor cavity includes a front reaction section 1, a rear reaction section 2 and a gas-solid separation section 6 from bottom to top. A cyclone separator is installed at the top of the gas-solid separation section 6, and heat exchange tubes of heat exchangers are installed in the front reaction section 1 and the rear reaction section 2.

[0068] The front reaction section 1 is equipped with a second gas distributor 10 connected to the second gas phase inlet 12 (in this embodiment, the second gas distributor 10 adopts the conventional gas distributor used in the ammonia oxidation reaction in the prior art), and the rear reaction section 2 is equipped with a first gas distributor 11 connected to the first gas phase inlet 13; the outlet end of the rear reaction section 2 is configured as an upwardly tapering constriction, and the small end of the constriction extends into the gas-solid separation section to form a columnar lifting section 5. The top of the columnar lifting section 5 is provided with downwardly curved arc-shaped baffles at intervals.

[0069] The gas-solid separation section 6 and the pre-reaction section 1 are connected by an external circulation pipe 8 located outside the reactor. A catalyst oxygenator is installed on the external circulation pipe to form an external circulation pipe for the catalyst particles. The post-reaction section 2 is provided with an annular baffle 4 with multiple through holes 401 on its sidewall. The first gas distributor 11 is located in the area defined by the annular baffle 4. The annular gap between the annular baffle 4 and the cavity wall of the post-reaction section 2 forms an inner circulation zone 3. The bottom end of the annular baffle is connected to an annular shell 402 with an upwardly tapering bottom opening.

[0070] The first gas distributor 11 includes: multiple gas distribution units and a main pipe 1101 arranged in the H direction to communicate with the first gas phase inlet 13. The multiple gas distribution units are arranged at intervals along the axial direction of the main pipe 1101.

[0071] Each air distribution unit includes multiple branch pipes 1103 and multiple branch pipes 1102. The inner ends of the multiple branch pipes are arranged circumferentially on the side of the main pipe and connected to the main pipe 1101. The outer ends are closed. The branch pipes 1103 are annular. The multiple branch pipes 1103 are arranged concentrically. Each branch pipe 1102 extends along the radial direction of the branch pipe 1103 and is connected. Multiple nozzles 1104 are arranged on each branch pipe 1102 and each branch pipe 1103. The multiple nozzles 1104 are arranged at intervals along the length of the pipe (branch pipe or branch pipe) they are on, and two adjacent nozzles on the same pipe are arranged symmetrically about the axis of the pipe.

[0072] The method for ammonia oxidation of aromatics using the above-mentioned gas-solid fluidized bed reactor includes: 1) introducing a mixed feedstock containing ammonia and aromatics into the second gas phase inlet 12; 2) introducing oxygen-containing gas into the first gas phase inlet 13.

[0073] The general process of this method includes: a catalyst is packed at the bottom of the reactor; ammonia and gasified aromatics are introduced into the reactor through an ammonia distributor (second gas distributor 10, with an opening rate of 0.045%) located in the pre-reaction section 1, where they contact the catalyst in the pre-reaction section 1 and undergo a preliminary reaction. The gas-solid mixture flows upward into the post-reaction section 2, where air (oxygen) is supplied through an oxygen distributor (first gas distributor 11), allowing the unreacted aromatic feedstock and intermediate products from the pre-reaction section 1 to continue the ammonia oxidation reaction (post-reaction). A portion of the gas-solid mixture exiting the post-reaction section 2 moves upward through a rapid lifting structure, while the remainder moves downward through an internal circulation zone 3. The solid catalyst exiting the internal circulation zone 3 participates again in the ammonia oxidation reaction in the pre-reaction section; the gas-solid mixture moving upward through the rapid lifting structure undergoes gas-solid separation in the gas-solid separation section 6, while the solid catalyst moves downward and circulates through an external circulation pipe 8. The catalyst particles enter the catalyst oxygenator along the pipeline, and after oxygen supplementation, they enter the pre-reaction section at the bottom of the reactor through the pipeline for another ammonia oxidation reaction. In the gas-solid separation section 6, the gas after gas-solid separation carries a small amount of solid particles upwards and undergoes gas-solid separation again through the cyclone separator 7 at the top of the reactor. The gas phase product flows out from the outlet 15 at the top of the device and enters the product collection device. After washing, filtering, dehydration, drying and other processes, the target product, aromatic nitrile, is finally obtained.

[0074] It should be noted that the present invention may employ a catalyst V with silica as a support and vanadium, chromium, boron, etc., as the main active components. 1.0 Cr 0.9 B 0.5 P 0.5 Ti 0.1 Mo 0.1 W 0.05 K 0.05 / SiO2, the average particle size of the catalyst is 200 mesh.

[0075] Example 1

[0076] Structural parameters: The cross-sectional area of ​​the inner circulation zone 3 is 1 / 8 of the cross-sectional area of ​​the rear reaction section 2; the angle β between the sidewall of the annular shell 402 and the sidewall of the annular partition 4 is 45°; the oxygen gas distributor (first gas distributor 11) located in the rear reaction section is arranged along the gas flow direction, and four layers of gas distribution units are arranged along the main pipe, with the spacing L in the H direction increasing sequentially. n :L n-1 =1.2 times; 6 branch pipes are symmetrically arranged along the main pipe axis in each layer, and the angle α between them and the main pipe is 60°; each pair of adjacent branch pipes is connected by 6 ring branch pipes, and the angle γ between two adjacent nozzles on the same pipe is 60°; the total opening rate of the oxygen gas distributor is 2%; the cross-sectional area of ​​the columnar lifting section 5 is 1 / 2 of the cross-sectional area of ​​the post-reaction section 2.

[0077] Method parameters: Pre-reaction section 1 temperature 385℃, post-reaction section 2 temperature 425℃, columnar riser section 5 temperature 380℃, internal circulation zone 3 temperature 380℃, catalyst oxygenator temperature 470℃; total catalyst weight load 0.10h. -1 The molar ratio of xylene:ammonia:air in the feed to the ammonia gas distributor (second gas distributor 10) and the oxygen gas distributor (first gas distributor 11) is 1:4:26.

[0078] The reaction achieved a xylene conversion rate of 99.6%, a phthalonitrile selectivity of 85.1%, and a CO2 selectivity of 7.3%.

[0079] Example 2

[0080] Structural parameters: The cross-sectional area of ​​the inner circulation zone 3 is 1 / 4 of the cross-sectional area of ​​the rear reaction section 2; the angle β between the sidewall of the annular shell 402 and the sidewall of the annular partition 4 is 60°; the oxygen gas distributor (first gas distributor 11) located in the rear reaction section is arranged along the gas flow direction, and four layers of gas distribution units are arranged along the main pipe, with the spacing L in the H direction increasing sequentially. n :L n-1 = 1.5 times; 10 branch pipes are symmetrically arranged along the main pipe axis in each layer, and the angle α between them and the main pipe is 30°; each pair of adjacent branch pipes is connected by 6 ring branch pipes, and the angle γ between two adjacent nozzles on the same pipe is 60°; the total opening rate of the oxygen gas distributor is 6%; the cross-sectional area of ​​the columnar lifting section 5 is 4 / 5 of the cross-sectional area of ​​the post-reaction section 2.

[0081] Method parameters: Pre-reaction section 1 temperature 400℃, post-reaction section 2 temperature 425℃, columnar riser section 5 temperature 380℃, internal circulation zone 3 temperature 380℃, catalyst oxygenator temperature 470℃; total catalyst load by weight 0.15h. -1The molar ratio of xylene:ammonia:air in the feed to the ammonia gas distributor (second gas distributor 10) and the oxygen gas distributor (first gas distributor 11) is 1:4:30.

[0082] The reaction achieved a xylene conversion rate of 99.0%, a phthalonitrile selectivity of 82.3%, and a CO2 selectivity of 10.6%.

[0083] Example 3

[0084] Structural parameters: The cross-sectional area of ​​the inner circulation zone 3 is 1 / 6 of the cross-sectional area of ​​the rear reaction section 2; the angle β between the sidewall of the annular shell 402 and the sidewall of the annular partition 4 is 35°; the oxygen gas distributor (first gas distributor 11) located in the rear reaction section is arranged along the gas flow direction, and 6 layers of gas distribution units are arranged along the main pipe, with equal spacing L in the H direction. n :L n-1 = 1 times; 15 branch pipes are symmetrically arranged along the main pipe axis in each layer, and the angle between them and the main pipe is α = 75°; each pair of adjacent branch pipes is connected by 6 annular branch pipes, and the angle γ between two adjacent nozzles on the same pipe is 110°; the total opening rate of the oxygen gas distributor is 9%; the cross-sectional area of ​​the columnar lifting section 5 is 1 / 5 of the cross-sectional area of ​​the post-reaction section 2.

[0085] Method parameters: Pre-reaction section 1 temperature 385℃, post-reaction section 2 temperature 425℃, columnar riser section 5 temperature 380℃, internal circulation zone 3 temperature 380℃, catalyst oxygenator temperature 470℃; total catalyst weight load 0.10h. -1 The molar ratio of xylene:ammonia:air in the feed to the ammonia gas distributor (second gas distributor 10) and the oxygen gas distributor (first gas distributor 11) is 1:5:28.

[0086] The reaction achieved a xylene conversion rate of 99.9%, a phthalonitrile selectivity of 85.3%, and a CO2 selectivity of 6.9%.

[0087] Example 4

[0088] Unlike Example 1, L n :L n-1 =2 times.

[0089] The reaction achieved a xylene conversion rate of 99.5%, a phthalonitrile selectivity of 79.6%, and a CO2 selectivity of 13.4%.

[0090] Example 5

[0091] Unlike Embodiment 1, the angle β between the sidewall of the annular housing 402 and the sidewall of the annular partition 4 is 75°. Each layer of branch pipes is symmetrically arranged with 3 pipes along the main pipe axis, and the angle α between them and the main pipe is 90°. The angle γ between two adjacent nozzles on the same pipe is 135°.

[0092] The reaction achieved a xylene conversion rate of 99.3%, a phthalonitrile selectivity of 77.1%, and a CO2 selectivity of 15.6%.

[0093] Example 6

[0094] Unlike Embodiment 1, the annular partition 4 and the annular shell 402 are not installed inside the cavity, that is, there is no internal circulation zone 3.

[0095] The reaction achieved a xylene conversion rate of 99.9%, a phthalonitrile selectivity of 81.7%, and a CO2 selectivity of 11.2%.

[0096] Example 7

[0097] Unlike Example 1, no external circulation pipe 8 and catalyst oxygenator are provided, and no annular baffle 4 and annular shell 402 are provided in the cavity, that is, the internal and external circulation process of catalyst particles is not adopted.

[0098] The reaction achieved a xylene conversion rate of 98.7%, a phthalonitrile selectivity of 69.4%, and a CO2 selectivity of 23.5%.

[0099] Example 8

[0100] The difference from Example 1 is that the molar ratio of xylene:ammonia:air in the ammonia gas distributor (second gas distributor 10) and the oxygen gas distributor (first gas distributor 11) is 1:5:30.

[0101] The reaction achieved a xylene conversion rate of 99.5%, a terephthalonitrile selectivity of 88.1%, and a CO2 selectivity of 7.1%.

[0102] Comparative Example 1

[0103] A conventional fine-particle fluidized bed ammonia oxidation reactor was used, with the same reactor size as in Example 1. The difference was the absence of a pre-reaction section 1, a post-reaction section 2, an internal circulation zone 3, an external circulation pipe 8, a catalyst oxygenator, and a rapid lifting structure; the reaction was completed within the same fluidized bed reaction zone. The reactor was arranged from bottom to top as follows: an air inlet pipe, an air distributor (upper opening ratio 1.5%, lower opening ratio 0.15%, where the air distributor is a plate distributor with a short pipe attached to the bottom; the lower opening ratio refers to the ratio of the opening area at the lower end of the short pipe to the cross-sectional area of ​​the reactor; the upper opening ratio is the ratio of the opening area at the upper end of the short pipe, i.e., the opening area of ​​the distribution plate, to the cross-sectional area of ​​the reactor), and an aromatics / ammonia distributor (opening ratio 0.045%). The structural diagram is shown below. Figure 7As shown, a settling zone and a cyclone separator are set at the top of the reactor. The separated solid catalyst particles are returned to the fluidized bed, while the gaseous product flows out from the top outlet and enters the product collection device. After washing, filtration, dehydration, drying and other processes, the target product, isophthalonitrile, is finally obtained.

[0104] The reaction temperature was 415℃, and the total catalyst loading was 0.08 h⁻¹. -1 The molar ratio of xylene:ammonia:air in the ammonia gas distributor and the oxygen gas distributor is 1:7:40.

[0105] The reaction yielded a xylene conversion of 95.6%, a phthalonitrile selectivity of 76.1%, and a CO2 selectivity of 17.5%.

[0106] Comparative Example 2

[0107] Unlike Example 1, both the ammonia gas distributor (second gas distributor 10) and the oxygen gas distributor (first gas distributor 11) adopt the form of gas distributors in the prior art, as shown in the schematic diagram below. Figure 7 As shown, the feed molar ratio of xylene: ammonia: air is 1:7:36.

[0108] The reaction achieved a xylene conversion rate of 96.3%, a phthalonitrile selectivity of 78.3%, and a CO2 selectivity of 15.1%.

[0109] Comparative Example 3

[0110] Unlike Comparative Example 1, the molar ratio of the feed to the ammonia gas distributor and the oxygen gas distributor is xylene:ammonia:air = 1:7:40;

[0111] The reaction achieved a xylene conversion of 98.3%, a isophthalonitrile selectivity of 86.7%, and a CO2 selectivity of 8.5%.

[0112] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A process for the ammoxidation of an aromatic hydrocarbon, characterized in that, The method adopts a gas-solid fluidized reactor, The bottom of the cavity of the gas-solid fluidized reactor is provided with a second gas distributor (10) communicating with a second gas inlet (12), and the upper portion of the second gas distributor (10) is provided with a first gas distributor (11), and the gas inlet of the branch pipe (1102) of the first gas distributor (11) communicates with a first gas inlet (13); the first gas distributor (11) comprises: A plurality of air distribution units are arranged at intervals along the H direction, and a plurality of H-direction intervals L between adjacent two air distribution units are formed, and the plurality of H-direction intervals L are equal or sequentially increase along the H direction; Each air distribution unit comprises a branch pipe (1102) with a gas inlet, a plurality of branch pipes (1103) are communicated with the branch pipe (1102), and a plurality of nozzles (1104) are arranged on the branch pipe (1102) and each branch pipe (1103); The method comprises: 1) passing a mixed raw material containing ammonia and aromatic hydrocarbons into the second gas inlet (12), and dispersing into the cavity through the second gas distributor (10) to contact with the oxygen-containing gas carried by the catalyst to generate a preliminary aromatic nitrile-containing stream; 2) passing the oxygen-containing gas into the first gas inlet (13), and dispersing into the cavity through the first gas distributor (11) to contact with the preliminary aromatic nitrile-containing stream to generate a later-stage aromatic nitrile-containing stream; Wherein, the cavity comprises a front reaction section (1), a rear reaction section (2) and a gas-solid separation section (6) which are communicated with each other from bottom to top, the second gas distributor (10) is installed in the front reaction section (1), and the first gas distributor (11) is installed in the rear reaction section (2), The rear reaction section (2) is provided with an annular partition plate (4), the first gas distributor (11) is arranged in the region defined by the annular partition plate (4), and the annular gap between the annular partition plate (4) and the cavity wall of the rear reaction section (2) forms an internal circulation zone (3).

2. The method of claim 1, wherein, Along the H direction, a plurality of the H-direction intervals L are sequentially named as L1...L n , wherein L n : L n-1 =1~1.5; And / or The total opening rate of the gas distributor is 0.1%-10%.

3. The method of claim 1, wherein, A plurality of nozzles (1104) are arranged at intervals along the length direction of each branch pipe (1102), and adjacent two nozzles (1104) on the same branch pipe (1102) are symmetrically arranged about the axis of the branch pipe (1102) and have an included angle γ; and / or A plurality of nozzles (1104) are arranged at intervals along the length direction of each branch pipe (1103), and adjacent two nozzles (1104) on the same branch pipe (1103) are symmetrically arranged about the axis of the branch pipe (1103) and have an included angle γ.

4. The method of claim 3, wherein, γ is 30-120°.

5. The method of claim 1, wherein, The gas distributor further comprises a main pipe (1101) arranged in H direction, the bottom end of the main pipe (1101) is open for gas inlet, in each gas distribution unit, a plurality of branch pipes (1102) are arranged on the side of the main pipe (1101) and communicated with the main pipe (1101).

6. The method according to claim 5, wherein, In each gas distribution unit, the number of branch pipes (1102) is 4-16, and the included angle α between the axis of each branch pipe (1102) and the axis of the main pipe (1101) is 30-90°.

7. The method of claim 6, wherein, α is 30-75°.

8. The method of claim 1 or 5, wherein, In each gas distribution unit, a plurality of branch pipes (1103) are arranged on both sides of the branch pipe (1102), or A plurality of branch pipes (1103) are radially arranged on the side of the branch pipe (1102).

9. The method of claim 1 or 5, wherein, The branch pipe (1103) is annular, each branch pipe (1102) is arranged in the radial direction of the branch pipe (1103), the inner end of the branch pipe (1102) is communicated with the side of the main pipe (1101), and the end of the outer end is closed.

10. The method according to claim 1 or 5, wherein, The bottom end of the main pipe (1101) of the first gas distributor (11) is communicated with the first gas inlet (13).

11. The method according to claim 1, wherein, A quick lifting structure is arranged in the cavity for shortening the residence time of the material in the post-reaction section.

12. The method according to claim 11, wherein, The quick lifting structure comprises a tapered neck arranged at the outlet end of the post-reaction section (2).

13. The method according to claim 12, wherein, The small end of the neck extends to the gas-solid separation section to form a cylindrical lifting section (5).

14. The method according to claim 13, wherein, The cross-sectional area of the cylindrical lifting section (5) is 1 / 5-4 / 5 of the cross-sectional area of the post-reaction section (2).

15. The method according to claim 1, wherein, A plurality of through holes (401) are arranged on the side wall of the annular partition plate (4), the through holes (401) enable the annular partition plate (4) to flow into the inner circulation zone (3) around the solid particles in the defined area; And / or The bottom end of the annular partition plate (4) is connected with an annular shell (402), the annular shell (402) is formed as a tapered bottom end opening, the included angle β between the side wall of the annular shell (402) and the side wall of the annular partition plate (4) is 30-60°; and / or The cross-sectional area of the inner circulation zone (3) is 1 / 10-1 / 2 of the cross-sectional area of the post-reaction section (2).

16. The method of claim 1, wherein, The gas-solid fluidized reactor is provided with an outer circulation unit, the outer circulation unit comprises a catalyst regenerator (9) and is communicated with the front reaction section (1) and the gas-solid separation section (6), for leading part of the catalyst in the gas-solid separation section (6) out, regenerating and then feeding into the front reaction section (1).

17. The method of claim 16, wherein, The catalyst regenerator (9) is selected from a catalyst oxygen supplement device.

18. The method of claim 1, wherein, Part of the solid catalyst in the post-reaction section is returned to the pre-reaction section (1) through the internal circulation zone (3); and / or Part of the catalyst in the gas-solid separation section (6) is fed to the pre-reaction section after being regenerated by the external circulation unit; And / or The total catalyst weight loading was 0.07 to 0.2 h -1 .

19. The method according to claim 18, wherein, The total catalyst weight loading was 0.09 to 0.15 h -1 .

20. The method according to claim 18 or 19, wherein, Step 1) is carried out in the pre-reaction section (1), and the temperature of the pre-reaction section (1) is controlled to be 350-410°C; And / or Step 2) is carried out in the post-reaction section (2), and the temperature of the pre-reaction section (1) is controlled to be 400-450°C; And / or The temperature of the cylindrical lifting section (5) and the internal circulation zone (3) is controlled to be 360-400°C; And / or The temperature of the catalyst oxygen supplement device is controlled to be 460-500°C; And / or The molar ratio of the feedings of the second gas distributor (10) and the first gas distributor (11) is aromatic hydrocarbon:ammonia:air = 1:3-8:20-40.

21. The method according to claim 20, wherein, m-xylene:ammonia:air = 1:4-5:25-30.

Images