Device and method for lightening aniline tar by hydrogenation

Abstract

The invention relates to a device and a method for lightening aniline tar by hydrogenation. An injection loop reactor is adopted. The bottom of the reaction kettle is communicated with a heat exchanger through a circulating pump; the heat exchanger is communicated with a Venturi ejector arranged at the top end of the reaction kettle; the venturi ejector comprises an inlet section, a nozzle, a mixing section and a diffusion section which are communicated in sequence, the peripheries of the inlet section and the nozzle are provided with a tapered annular gas chamber, the gas chamber is communicated with the mixing section, and the gas chamber is communicated with a gas inlet formed in the upper part of the reaction kettle through a gas circulating pipe; and a feeding hole is formed in the feeding pipe. According to the invention, the injection loop reactor is adopted, the solid powder Ni-based catalyst is taken as the catalyst, and the strong mass transfer effect of the Venturi injection reactor is utilized, so that the reaction difficulty is reduced, the reaction time is effectively shortened, the hydrogenation lightening of the aniline tar is smoothly carried out, and meanwhile, the economic additional value of comprehensive utilization of the aniline tar is improved.

Description

Technical Field

[0001] The present invention belongs to the comprehensive utilization technology of aniline tar, the refining residue of aniline prepared by gas phase method, and specifically relates to a device and method for hydrogenating and lightening aniline tar by using a new reactor equipment, namely, a jet loop reactor. Background Art

[0002] Aniline tar residue is a black viscous liquid with a fishy odor. Its main component is aromatic hydrocarbons with strong electronegativity. For a long time, people generally use it as fuel and waterproof material. Most of them are treated by incineration, which will cause environmental pollution. There are also many studies on aniline tar hydrocracking technology at home and abroad, which mainly focus on the research of hydrocracking catalyst. The aniline tar hydrogenation process of the present invention is based on the analysis of its composition, using a new type of venturi jet loop reactor, using a cheap and easily available Ni-based catalyst to hydrorefining or catalytic cracking the substances therein, so that they are decomposed into small molecules to generate target products, while reducing pollution and increasing its economic added value.

[0003] The hydrogenation and lightening of aniline tar is different from the hydrogenation of monomeric aniline to prepare cyclohexylamine. The traditional hydrogenation of monomeric aniline to prepare cyclohexylamine mostly adopts fixed bed or autoclave, uses cobalt catalyst, reaction pressure of 14-24MPa, reaction temperature of 240℃, and has high requirements for reaction equipment. The gas quality analysis of aniline tar residues from different batches of a certain factory showed that the aniline content in aniline tar was 35%-65%, and o-aminodiphenylamine was about 15%. Other possible substances were aniline dimer, aniline trimer, phenylhydrazine, o-aminophenol, p-aminophenol, N-phenyl-p-phenylenediamine, etc. Aniline tar is black and viscous with complex components and strong electronegativity. It is difficult to hydrogenate and lighten it using ordinary Ni-based catalysts in traditional reactors or fixed beds.

[0004] The loop reactor is a new type of reactor system, which is specifically composed of a reactor, a circulating pump, a heat exchanger and a venturi ejector (mixer). The reaction liquid circulates in the loop at a large flow rate and is ejected at high speed through the venturi ejector, forming a negative pressure at the working nozzle, so that the gas participating in the reaction is sucked into the ejector to form micron-sized bubbles with a large specific surface area, increasing the gas-liquid contact and forming an emulsification effect of the gas-liquid two phases, effectively increasing the mass transfer effect, making the reaction easier to proceed and thus accelerating the reaction rate. Summary of the invention

[0005] The present invention provides a process for hydrogenating and lightening aniline tar using a jet loop reactor, which solves the environmental pollution problem during the current comprehensive utilization of aniline tar, thereby improving its added value and increasing revenue.

[0006] The device for hydrogenating and lightening aniline tar provided by the present invention is a jet loop reactor, which mainly comprises a reactor, a circulation pump, a heat exchanger and a venturi ejector; the bottom of the reactor is connected with the heat exchanger through the circulation pump; the heat exchanger is connected through the venturi ejector arranged at the top of the reactor; the venturi ejector comprises an inlet section, a nozzle, a mixing section and a diffusion section which are connected in sequence; the inlet section and the nozzle are in a tapered tubular shape; a tapered annular air chamber is arranged on the periphery of the inlet section and the nozzle, and the air chamber is connected with the mixing section; the air chamber is connected with an air inlet arranged on the upper part of the reactor through a gas circulation pipe; the diffusion section is in a gradually expanding tubular type; the lower end of the venturi ejector is located below the liquid surface of the reaction material.

[0007] In some embodiments, it is more preferred that the specifications of the Venturi injector are: inner diameter of the inlet section opening: inner diameter of the nozzle: inner diameter of the air chamber closing: length of the mixing section: length of the diffusion section = 36: (1~4): (3~6): (60~150): (600~1400), and the opening angle of the diffusion section is 10~20°.

[0008] In some embodiments, most preferably, the specifications of the Venturi injector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 36:2.5:4.5:105:1000, and the opening angle of the diffusion section is 15°.

[0009] The present invention improves the design of the venturi ejector to make it suitable for aniline tar hydrogenation. The present invention utilizes the effect of bubbles in the jet loop reactor to segment and shear the liquid in the jet mixing area (mixing section and diffusion section of the venturi ejector) and the liquid in the reactor, promotes diffusion and mass transfer between liquids, and strongly stirs the heterogeneous system formed by the aniline tar-methanol-solid powder catalyst-hydrogen of the present invention, thereby accelerating the chemical reaction rate. The present invention obtains process conditions more suitable for the hydrogenation and light-weighting preparation of aniline tar of the present invention by exploring the production process parameters, so that the reaction proceeds smoothly and a higher yield of cyclohexylamine is obtained.

[0010] The present invention also provides a method for hydrogenating and lightening aniline tar using the above-mentioned jet loop reactor, using residual aniline tar (aniline content 35-65%) after aniline distillation prepared by a gas phase method as a raw material, a solid powder Ni-based catalyst as a catalyst, hydrogen is introduced into the jet loop reactor during the reaction, and the reaction pressure is maintained, hydrogenation and lightening are carried out, and the proportion of cyclohexylamine in the product is greater than 85%.

[0011] In some embodiments, the preferred reaction uses methanol as solvent, and the mass ratio of methanol to aniline tar is 1:1.

[0012] In some embodiments, the catalyst is a Ni-based catalyst or Raney nickel, wherein the Ni-based catalyst carrier includes but is not limited to a general acidic carrier such as SiO 2 、Al 2 O 3 , MgO, molecular sieve ZSM-5, etc.

[0013] In some embodiments, the preferred amount of catalyst is 2%-6% of the mass of aniline tar, and the more preferred amount is 4% of the mass of aniline tar.

[0014] In some embodiments, the preferred loading amount of Ni in the Ni-based catalyst is 15-35% of the carrier mass, and the more preferred loading amount is 20% of the carrier mass.

[0015] In some embodiments, the preferred reaction time is 2-4 h, and the more preferred reaction time is 3 h.

[0016] In some embodiments, the preferred reaction temperature is 170-210°C, and the more preferred reaction temperature is 190°C.

[0017] In some embodiments, the preferred reaction pressure is 3-8 MPa, and the more preferred reaction pressure is 5 MPa.

[0018] In some embodiments, in a more preferred reaction process, the linear velocity of the fluid at the nozzle of the venturi injector is controlled to be 80-120 m / s, more preferably 100 m / s.

[0019] The present invention adopts a jet loop reactor and a solid powder Ni-based catalyst as a catalyst, and utilizes the powerful mass transfer effect of the improved Venturi jet reactor to reduce the difficulty of the reaction, effectively shorten the reaction time, and make the hydrogenation and lightening of aniline tar proceed smoothly, while improving the economic added value of the comprehensive utilization of aniline tar. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the connection structure of the aniline tar hydrogenation lightening device according to an embodiment of the present invention.

[0021] Figure 2 Schematic diagram of the structure of the venturi ejector in the embodiment.

[0022] Figure 1 In the figure, 1-reactor, 2-Venturi ejector, 3-heat exchanger, 4-circulation pump, 5-gas circulation pipe, 6-inlet section, 7-mixing section, 8-diffusion section, 9-nozzle, 10-gas chamber.

[0023] Figure 2In the figure, D1 is the inner diameter of the inlet section opening, D2 is the inner diameter of the nozzle, D3 is the inner diameter of the air chamber closing, L1 is the length of the mixing section, L2 is the length of the diffusion section, and α is the opening angle of the diffusion section. Implementation

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0025] A device for hydrogenating and lightening aniline tar Figure 1 and 2 The device is a jet loop reactor, which mainly includes a reactor 1, a circulation pump 4, a heat exchanger 3 and a venturi ejector 2; the bottom of the reactor 1 is connected to the heat exchanger 3 through the circulation pump 4; the heat exchanger 3 is connected through the venturi ejector 2 arranged at the top of the reactor 1; the venturi ejector 2 includes an inlet section 6, a nozzle 9, a mixing section 7, and a diffusion section 8 which are connected in sequence; the inlet section 6 and the nozzle 9 are in a tapered tubular shape; a tapered annular air chamber 10 is arranged on the periphery of the inlet section 6 and the nozzle 9, and the air chamber 10 is connected to the mixing section 7; the air chamber 10 is connected to the air inlet arranged on the upper part of the reactor 1 through a gas circulation pipe 5; the diffusion section 8 is a gradually expanding tube type; the lower end of the venturi ejector 2 is located below the liquid level of the reaction material.

[0026] Embodiment The above-mentioned device is used to carry out hydrogenation lightening treatment on aniline tar, using aniline tar (aniline content 35-65%) residual after aniline distillation prepared by a gas phase method in a certain factory as raw material, solid powder Ni-based catalyst as catalyst, hydrogen is introduced into the jet loop reactor during the reaction process, and the reaction pressure is maintained to carry out hydrogenation lightening.

[0027] Catalyst preparation Reagents used: The fumed silica carrier comes from Wacker Chemicals of Germany, with a specific surface area of ​​S BET =150 m 2 / g (hydrophilic type); Ni(NO3)2·6H2O (Sinopharm Chemical Reagent Co., Ltd. AR); The alumina carrier comes from the Jinling Petrochemical Alkylbenzene Plant, with a diameter of 1-2 mm and is spherical and ground into powder. BET =211 m 2 / g.

[0028] MgO (Sinopharm Chemical Reagent Co., Ltd. AR) Weigh nickel nitrate hexahydrate and dissolve it in an appropriate amount of deionized water, add a measured amount of carrier silica powder so that the Ni content in the catalyst is 20% of the carrier mass. Stir and immerse in a water bath at 80 °C until the solution evaporates to dryness, transfer the catalyst to a muffle furnace, heat it to 500 °C at 5 °C / min, and roast it for 6 hours. Grind and sieve the calcined catalyst to 150 mesh, heat the powder catalyst to 450 °C at 3 °C / min with hydrogen, reduce it for 4 hours, cool it naturally to room temperature, and slowly passivate it with a nitrogen and oxygen (oxygen content 0.5%) mixed gas until the catalyst no longer heats up.

[0029] The method for preparing catalysts with other supports is the same as above.

[0030] Screening Examples to Determine Catalyst Ni Loading Range

[0031] In this example, the Ni catalyst was changed to SiO 2 The loading on the aniline tar is compared to the percentage of cyclohexylamine in the product. The other production process parameters are: the amount of catalyst is 3.5% of the mass of aniline tar, the reaction pressure is 4.5MPa, the reaction temperature is 180℃, the reaction time is 3.5h, and the specifications of the venturi injector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = 36:3:4:90:900, the opening angle of the diffusion section is 12°, and the fluid linear velocity at the nozzle of the venturi injector during the reaction is 115m / s. The actual percentage of cyclohexylamine in the hydrogenation product of aniline tar catalyzed by catalysts with different Ni loadings is shown in the following table.

[0032]

[0033] As shown in Table 1 above, the optimal loading amount of catalyst Ni is 15-35%. Embodiment 1 (optimal)

[0034] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 2 60 g of catalyst (Ni loading is 20% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times. The pressure was raised to a reaction pressure of 5 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 190°C through a heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 100 m / s, which was recorded as the start time of the reaction.

[0035] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the venturi ejector was controlled to be 100 m / s. The detailed design dimensions were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 36: (2.5): (4.5): (105): (1000), the diffusion section opening angle α was 15°, the reaction was continued for 3h, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (the cooling time was about 15min), and the product was taken after venting and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 90.6% in the product. Example 2

[0036] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 2 37.5 g of catalyst (Ni loading is 25% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times, and the pressure was increased again to a reaction pressure of 3.5 MPa. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly, and the temperature was raised to 175°C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 105 m / s, which was recorded as the start time of the reaction.

[0037] During the reaction, the temperature of the connected reactor was controlled to be 175±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 105 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:1.5:3:75:700, and the diffusion section opening angle α was 15°. After reacting for 2.5 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was quickly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 85.1% in the product. Example 3

[0038] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 2 82.5 g of catalyst (Ni loading is 30% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times, and the pressure was increased again to a reaction pressure of 7.5 MPa. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly, and the temperature was raised to 205°C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 95 m / s, which was recorded as the start time of the reaction.

[0039] During the reaction, the temperature of the connected reactor was controlled to be 205±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 95 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:2:4:80:800, and the diffusion section opening angle α was 18°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 86.3% in the product. Example 4

[0040] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / Al 2 O 3 52.5 g of catalyst (Ni loading is 16% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After the leak detection, the reactor was vented and replaced three times. The pressure was raised to a reaction pressure of 4.5 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 180°C through a heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 115 m / s, which was recorded as the start time of the reaction.

[0041] During the reaction, the temperature of the connected reactor was controlled to be 180±1°C. The linear velocity of the fluid at the nozzle of the venturi ejector was controlled to be 115 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:3:4:90:900, and the diffusion section opening angle α was 12°. After the reaction was continued for 3.5 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 87.5% in the product. Example 5

[0042] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / Al 2 O 3 75 g of catalyst (Ni loading is 22% of the carrier mass) was dispersed with stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the system was vented and replaced three times, and the pressure was increased again to a reaction pressure of 5.5 MPa. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly, and the temperature was raised to 190°C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 85 m / s, which was recorded as the start time of the reaction.

[0043] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the venturi ejector was controlled to be 85 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:3.5:5.5:100:1100, and the diffusion section opening angle α was 14°. After reacting for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was quickly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 88.4% in the product. Example 6

[0044] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / Al 2 O 3 67.5 g of catalyst (Ni loading is 32% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times. The pressure was increased again to a reaction pressure of 6.5 MPa. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 205°C through a heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 120 m / s, which was recorded as the start time of the reaction.

[0045] During the reaction, the temperature of the connected reactor was controlled to be 205±1°C. The linear velocity of the fluid at the nozzle of the venturi ejector was controlled to be 120 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:3:5:140:1350, and the diffusion section opening angle α was 16°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 85.6% in the product. Example 7

[0046] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. Stir and disperse 75 g of a commercial Raney nickel catalyst and inject the above mixture into a 5 L loop reactor. Pass hydrogen into the reactor through the air inlet to the system pressure of 8 MPa to check for leaks. After the leak detection is completed, vent and replace three times, and increase the pressure to the reaction pressure of 5 MPa again. Start the circulation pump 4 to make the liquid in the kettle flow slowly, and heat it to 190°C through the heat exchanger (heating time is about 10 min). Quickly adjust the circulation pump 4 to the flow rate to 110 m / s, which is recorded as the start time of the reaction.

[0047] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 110 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:2.5:5:130:1250, and the diffusion section opening angle α was 18°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 86.2% in the product.

[0048] Comparative Example 1 Venturi design is out of range (optimal reaction conditions)

[0049] Take 1.5kg of aniline tar from a factory and dissolve it in 1.5kg of methanol. At the same time, add the passivated Ni / SiO 2 60 g of catalyst (Ni loading is 20% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times. The pressure was raised to a reaction pressure of 5 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 190°C through a heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 100 m / s, which was recorded as the start time of the reaction.

[0050] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 100 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:3:4:230:1750, and the diffusion section opening angle α was 8°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 62.8% in the product.

[0051] Comparative Example 2 (Optimal Venturi Reactor Design for Low Reaction Temperature)

[0052] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 260 g of catalyst (Ni loading is 20% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times. The pressure was raised to a reaction pressure of 5 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 150 ° C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 100 m / s, which was recorded as the start time of the reaction.

[0053] During the reaction, the temperature of the connected reactor was controlled to be 150±1°C. The linear velocity of the fluid at the nozzle of the venturi ejector was controlled to be 100 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:2.5:4.5:105:1000, and the diffusion section opening angle α was 15°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 32.6% in the product.

[0054] Comparative Example 3 (Optimal Venturi Reactor Design for Reaction Timeout)

[0055] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 2 60 g of catalyst (Ni loading is 20% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the system was vented and replaced three times, and the pressure was increased to a reaction pressure of 5 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly, and the temperature was raised to 190 ° C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 100 m / s, which was recorded as the start time of the reaction.

[0056] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 100 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:2.5:4.5:105:1000, and the diffusion section opening angle α was 15°. After the reaction was continued for 6 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 76.9% in the product.

[0057] Comparative Example 4 (Optimal Venturi Reactor Design for Low Reaction Pressure)

[0058] Take 1.5 kg of aniline tar and dissolve it in 1.5 kg of methanol. At the same time, add the passivated Ni / SiO 2 60 g of catalyst (Ni loading is 20% of the carrier mass) was dispersed by stirring and injected into a 5 L loop reactor. Hydrogen was introduced into the reactor through the air inlet to a system pressure of 8 MPa for leak detection. After leak detection, the reactor was vented and replaced three times. The pressure was raised to a reaction pressure of 2 MPa again. The circulation pump 4 was turned on to allow the liquid in the kettle to flow slowly. The temperature was raised to 190 ° C through the heat exchanger (heating time was about 10 min). The circulation pump 4 was quickly adjusted to a flow rate of 100 m / s, which was recorded as the start time of the reaction.

[0059] During the reaction, the temperature of the connected reactor was controlled to be 190±1°C. The linear velocity of the fluid at the nozzle of the Venturi ejector was controlled to be 100 m / s, and the detailed design dimensions were specifically the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 36:2.5:4.5:105:1000, and the diffusion section opening angle α was 15°. After the reaction was continued for 3 hours, the flow rate of the circulating pump 4 was immediately reduced and the temperature was rapidly cooled to room temperature (cooling time was about 15 minutes). After venting, the product was taken and analyzed by gas chromatography using the area normalization method to obtain a cyclohexylamine content of 55.8% in the product.

[0060] Comparative Example 5 Reactor

[0061] A 2L autoclave was charged with 600g of aniline tar, 600g of anhydrous methanol, and Ni / SiO 2 (Ni loading is 20% of the carrier mass) 24g of powder catalyst was pressurized with hydrogen at 8MPa for leak detection and replaced 3 times, then the pressure was increased to 5MPa again, stirring and heating were started, the speed was adjusted to 750 rpm, the temperature was increased to 190°C, which was marked as the start of the reaction. During the reaction, the reaction pressure was maintained at 5MPa by a pressure regulator. The reaction time was 3h. Gas chromatography analysis of the product after the reaction showed that cyclohexylamine accounted for 16.5%. Results Analysis

[0062] Examples 1-7 (among which Example 1 is the optimal example) show that using a conventional carrier loaded with a limited content of Ni catalyst and a commercial Raney nickel catalyst, within the design size ratio range of the Venturi injector protected by this patent, when using the process parameters protected by this patent (reaction time, reaction pressure, reaction temperature), a higher percentage of cyclohexylamine is obtained, and the proportion of cyclohexylamine in the product is greater than 85%, and the reaction result is good.

[0063] Comparative Example 1 shows that for the hydrogenation and lightening of aniline tar, the design size of the Venturi injector is crucial. For the Venturi design not within the specified range, under the same reaction conditions, the proportion of cyclohexylamine in the product is only 62.8%, which is significantly lower than the 90.6% of cyclohexylamine in the optimal Venturi design reaction.

[0064] Comparative Examples 2-4 show that when the reaction is carried out with the optimal Venturi design, the optimal catalyst loading and dosage, when the reaction conditions such as low reaction temperature, reaction overtime, and low reaction pressure are used (i.e., the reaction process parameters are not within the protection range), the percentage of cyclohexylamine in the product will be greatly reduced.

[0065] Comparative Example 5 shows that with the same process parameters (reaction temperature, reaction pressure, reaction time, the same catalyst and the same amount), using a traditional kettle reactor, the reaction conversion effect is very poor.

Claims

1. A device for hydrogenating and lightening aniline tar, characterized in that The device is a jet loop reactor, comprising a reactor, a circulation pump, a heat exchanger and a venturi ejector; the bottom of the reactor is connected to the heat exchanger through the circulation pump; the heat exchanger is connected through the venturi ejector arranged at the top of the reactor; the venturi ejector comprises an inlet section, a nozzle, a mixing section and a diffusion section which are connected in sequence; the inlet section and the nozzle are in a tapered tubular shape; a tapered annular air chamber is arranged on the periphery of the inlet section and the nozzle, and the air chamber is connected to the mixing section; the air chamber is connected to an air inlet arranged on the upper part of the reactor through a gas circulation pipe; the diffusion section is a gradually expanding tube type; the lower end of the venturi ejector is located below the liquid level of the reaction material.

2. The device according to claim 1, characterized in that The specifications of the Venturi ejector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 36: (1-4): (3-6): (60-150): (600-1400), and the opening angle of the diffusion section is 10-20°.

3. The device according to claim 2, characterized in that The specifications and dimensions of the Venturi ejector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = 36:2.5:4.5:105:1000, and the opening angle of the diffusion section is 15°.

4. A method for hydrogenating and lightening aniline tar, characterized in that Aniline tar is hydrogenated and lightened by using a device as claimed in any one of claims 1 to 3, using residual aniline tar after aniline distillation prepared by a gas phase method as a raw material, a solid powder Ni-based catalyst as a catalyst, hydrogen is introduced into a jet loop reactor during the reaction, and the reaction pressure is maintained, and the product is hydrogenated and lightened, and the proportion of cyclohexylamine in the product is greater than 85%.

5. The method according to claim 4, characterized in that The reaction uses methanol as solvent, the mass ratio of methanol to aniline tar is 1:1, and the amount of catalyst added is 2-6% of the mass of aniline tar; the reaction temperature is 170-210°C, the reaction pressure is 3-8MPa, and the reaction time is 120-240min.

6. The method according to claim 4 or 5, characterized in that During the reaction process, the linear velocity of the fluid at the nozzle of the Venturi ejector is controlled to be 80-120 m / s.

7. The method according to claim 4, characterized in that The Ni-based catalyst carrier includes SiO2, Al2O3, MgO, and molecular sieve ZSM-5.

8. The method according to claim 4, characterized in that The Ni content of the Ni-based catalyst is 15%-35% of the carrier mass.

9. The method according to claim 8, characterized in that The content of Ni loaded in the Ni-based catalyst is 20% of the carrier mass.

10. The method according to claim 5, characterized in that The mass ratio of methanol to aniline tar is 1:1, and the amount of catalyst added is 4% of the mass of aniline tar; during the reaction, the reaction temperature is controlled to be 190°C, the reaction pressure is 5MPa, and the fluid linear velocity at the venturi injector nozzle is 100m / s.

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