CN118084601A - Production method and production device for preparing benzene by cyclohexane dehydrogenation - Google Patents

Production method and production device for preparing benzene by cyclohexane dehydrogenation Download PDF

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Publication number
CN118084601A
CN118084601A CN202211497253.5A CN202211497253A CN118084601A CN 118084601 A CN118084601 A CN 118084601A CN 202211497253 A CN202211497253 A CN 202211497253A CN 118084601 A CN118084601 A CN 118084601A
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tower
outlet
cyclohexane
benzene
liquid phase
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丁辉
黄声骏
张大治
邹明明
焦雨桐
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Dalian Institute of Chemical Physics of CAS
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Dalian Institute of Chemical Physics of CAS
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/367—Formation of an aromatic six-membered ring from an existing six-membered ring, e.g. dehydrogenation of ethylcyclohexane to ethylbenzene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0036—Multiple-effect condensation; Fractional condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/005—Processes comprising at least two steps in series
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/04—Purification; Separation; Use of additives by distillation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
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  • Water Supply & Treatment (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The application discloses a production method and a production device for preparing benzene by cyclohexane dehydrogenation, wherein the production method comprises the following steps: (1) Raw materials containing cyclohexane I and air undergo oxidative dehydrogenation reaction to obtain a reaction product containing benzene, cyclohexene and water; (2) And (3) sequentially obtaining cyclohexane II and benzene after the reaction products are subjected to fractional gas-liquid separation, decantation separation, fractional condensation rectification I and fractional condensation rectification II. The method can be used for preparing benzene products by a cyclohexane dehydrogenation method, has continuous process and simple flow, saves high-grade cold energy consumption by fractional condensation, reduces the separation difficulty of azeotropic components by combining gravity decantation, obtains the benzene products by reasonably designing rectification parameters and adopting sequential azeotropic cyclic rectification on the premise of non-total sharp separation, and is suitable for industrialized large-scale continuous operation.

Description

Production method and production device for preparing benzene by cyclohexane dehydrogenation
Technical Field
The application relates to a production method and a production device for preparing benzene by cyclohexane dehydrogenation, and belongs to the technical field of chemical industry.
Background
Cyclohexane is a cyclohexene hydration product, is used as a chemical raw material and an intermediate with wide application, and plays an important role in the fields of solvent production, adhesive preparation, nylon synthesis and the like. In recent years, along with the increase of the productivity of the process for preparing cyclohexanone by cyclohexene hydration, the yield of byproduct cyclohexane is continuously increased, the sales pressure is continuously increased, and a downstream high-added-value product route is continuously opened. Benzene is a basic raw material of aromatic hydrocarbon chemical industry, the yield and the production technology level of the benzene are marks of the national petrochemical industry development level, the market is fatigued along with the great increase of cyclohexane productivity, the price of the cyclohexane is lower than that of pure benzene, and the cyclohexane is dehydrogenated to prepare benzene products, so that the benzene products are an effective way for improving the cyclohexane value.
The technical research on preparing benzene by cyclohexane dehydrogenation has already been completed on the catalyst, the traditional extraction rectification is adopted in the subsequent separation flow, and the product is obtained by adding an extractant and rectifying and separating the extractant. The process is additionally added with an extractant, equipment is required to be increased, the extractant can be separated and recycled, and explosive hydrogen is produced as a byproduct, so that the production has explosion danger. Therefore, the development of a safe and environment-friendly production process has a certain significance in academic research and market application.
Disclosure of Invention
The application provides a production method of unsaturated low-carbon hydrocarbon, which is characterized in that the method comprises the steps of preheating, reaction, split-phase and rectification, and setting the pressure of a rectifying tower according to the composition of components in raw materials, and refining the product by carrying out non-full sharp separation on azeotropic components and target products, thereby reducing the separation difficulty and being suitable for large-scale industrial production.
In one aspect of the application, a method for producing benzene by dehydrogenating cyclohexane is provided, which comprises the following steps:
(1) Raw materials containing cyclohexane I and air undergo oxidative dehydrogenation reaction to obtain a reaction product containing benzene, cyclohexene and water;
(2) And (3) sequentially obtaining cyclohexane II and benzene after the reaction products are subjected to fractional gas-liquid separation, decantation separation, fractional condensation rectification I and fractional condensation rectification II.
Optionally, step (1) further comprises:
The reaction product exchanges heat with the raw materials; the heat is recovered by heat exchange between the product and the reaction raw materials, so that the cold energy consumption is reduced.
Optionally, the reaction temperature of the oxidative dehydrogenation reaction is 300-600 ℃, and the reaction pressure is 0.1-3 MPaA.
Alternatively, the oxidative dehydrogenation reaction temperature is independently selected from any value or range of values between any two points of 300 ℃, 400 ℃, 410 ℃, 500 ℃, 600 ℃.
Alternatively, the oxidative dehydrogenation reaction pressure is independently selected from any of 0.1MPaA, 0.13MPaA, 0.5MPaA, 1MPaA, 2MPaA, 3MPaA, or a range between any two of the foregoing.
Optionally, the step (2) includes:
(a) The reaction product is subjected to fractional condensation to obtain a condensed liquid phase;
(b) Separating the condensed liquid phase by a decanting device to obtain an oil phase and a water phase;
(c) The oil phase is subjected to fractional condensation and rectification I through a recovery tower to obtain a liquid phase I and a mixture containing cyclohexane II;
(d) The liquid phase I is subjected to fractional condensation and rectification II by a product tower to obtain a liquid phase II and benzene;
mixing the liquid phase II with the oil phase in the recovery tower, and repeating the step (3);
Wherein in the step (1), the raw material further comprises the cyclohexane II.
Alternatively, the reaction product is condensed by fractionation, reducing the utility required for hydrogen separation.
Alternatively, the aqueous phase in the mixture is separated by a decantation operation, omitting the utility required for conventional rectification separation.
Optionally, product refinement on the premise of not all sharp separation is realized by utilizing the azeotropic characteristic of materials through rectification pressure design.
Optionally, the product overhead fraction is recycled to the recovery column for further separation after being pressurized.
Optionally, the grading gas-liquid separation comprises primary gas-liquid condensation and secondary gas-liquid condensation which are sequentially carried out;
the reaction product is subjected to primary gas-liquid cooling to obtain a gas phase I and a condensed liquid phase I;
the gas phase I is subjected to secondary gas-liquid condensation to obtain tail gas and condensed liquid phase II;
Wherein the condensation temperature of the primary gas-liquid condensation is 0-60 ℃ and the condensation pressure is 0.1-3 MPaA;
The condensing temperature of the secondary gas-liquid condensation is-60-0 ℃, and the condensing pressure is 0.1-3 MPaA.
Alternatively, the condensation temperature of the primary gas-liquid condensation is independently selected from any value or range of values between any two of the above values of 0 ℃,10 ℃, 20 ℃, 30 ℃, 42 ℃, 50 ℃, 60 ℃.
Optionally, the condensation pressure of the primary gas-liquid condensation is independently selected from any value of 0.1MPaA, 0.12MPaA, 0.5MPaA, 1MPaA, 2MPaA, 3MPaA or a range of values between any two of the above.
Optionally, the condensing temperature of the secondary gas-liquid condensate is independently selected from any value of-60 ℃, -50 ℃, -40 ℃, -30 ℃, -20 ℃, -10 ℃, 0 ℃ or a range of values between any two points of the foregoing.
Optionally, the condensing pressure of the secondary gas-liquid condensation is independently selected from any of 0.1MPaA, 0.11MPaA, 0.5MPaA, 1MPaA, 2MPaA, 3MPaA or a range of values between any two of the above.
Optionally, the decanting apparatus operates at a temperature of-60 to 0 ℃ and at a pressure of 0.1 to 3MPaA.
Alternatively, the operating temperature of the decanting apparatus is independently selected from any value of-60 ℃, -50 ℃, -40 ℃, -30 ℃, -20 ℃, -11 ℃, -10 ℃, 0 ℃ or a range of values between any two of the foregoing.
Alternatively, the operating pressure of the decanting apparatus is independently selected from any of 0.1MPaA, 0.5MPaA, 0.6MPaA, 1MPaA, 2MPaA, 3MPaA or a range of values therebetween.
Optionally, the temperature of the top of the recovery tower is 20-60 ℃, and the operation pressure of the bottom of the recovery tower is 0.1-3 MPaA;
the temperature of the top of the product tower is 20-60 ℃, and the operating pressure of the top of the product tower is 0-500 kPaA.
Alternatively, the top temperature of the recovery column is independently selected from any value or range of values between any two points of 20 ℃, 30 ℃, 42 ℃, 50 ℃, 60 ℃.
Alternatively, the bottom operating pressure of the recovery column is independently selected from any of 0.1MPaA, 0.48MPaA, 0.5MPaA, 1MPaA, 2MPaA, 3MPaA or a range between any two of the foregoing.
Alternatively, the product column overhead temperature is independently selected from any value or range of values between any two points above 20 ℃, 30 ℃, 42 ℃, 50 ℃, 60 ℃.
Alternatively, the overhead operating pressure of the product column is independently selected from any of 0kPaA, 50kPaA, 100kPaA, 120kPaA, 200kPaA, 300kPaA, 400kPaA, 500kPaA, or a range of values between any two of the foregoing.
In the present application, MPaA and kPaA refer to absolute pressures.
In another aspect, the application provides a production device for preparing benzene by dehydrogenating cyclohexane, which comprises an oxidative dehydrogenation reaction unit, a grading gas-liquid separation unit, a decanting device, a recovery tower and a product tower which are sequentially communicated;
The recovery tower and the product tower are rectifying towers;
The bottom of the recovery tower is provided with a mixture outlet containing the cyclohexane II;
And a benzene outlet is arranged at the bottom of the product tower.
Optionally, the oxidative dehydrogenation reaction unit comprises a heat exchanger, a preheater and an oxidative dehydrogenation reactor which are sequentially communicated;
The reaction product outlet I of the oxidative dehydrogenation reactor is communicated with the reaction product inlet of the heat exchanger; and a dehydrogenation reaction product outlet II of the heat exchanger is communicated with the fractional condensation unit.
Optionally, the fractional condensation unit comprises a condenser, a condensation tank, a cryocooler and a cryocooler which are sequentially communicated;
the condenser is communicated with the dehydrogenation reaction unit;
The condensing tank is provided with a condensed liquid phase I outlet;
the cryogenic tank is provided with a condensed liquid phase II outlet;
The condensed liquid phase I outlet and the condensed liquid phase II outlet are both communicated with the decanting device;
The cryogenic tank is provided with the tail gas outlet.
Optionally, the decanting device is provided with an oil phase outlet, and the oil phase outlet is communicated with the recovery tower;
the top of the recovery tower is provided with a gas phase outlet I, the side wall of the recovery tower is provided with a liquid phase outlet I, and the bottom of the recovery tower is provided with a mixture outlet containing cyclohexane II;
the mixture outlet containing the cyclohexane II is communicated with the heat exchanger through a pipeline;
The liquid phase outlet I is communicated with the product tower;
The tower top of the product tower is provided with a gas phase outlet II, the side wall of the tower is provided with a liquid phase outlet II, and the tower bottom is provided with a benzene outlet;
the liquid phase outlet II is communicated with the recovery tower.
Optionally, a pressurizing device, namely a pressurizing pump, is arranged between the product tower and the recovery tower according to the pressure difference.
Optionally, the reflux ratio of the recovery tower is 1-60, and the theoretical plate number is 10-80;
The reflux ratio of the product tower is 1-60, and the theoretical plate number is 10-80.
Optionally, the reflux ratio of the recovery tower is independently selected from any value of 1, 9, 10, 20, 30, 40, 50, 60 or a range of values between any two points.
Alternatively, the theoretical plate number of the recovery tower is independently selected from any value of 10, 20, 30, 40, 50, 60, 70, 80 or a range value between any two points.
Alternatively, the reflux ratio of the product column is independently selected from any of 1, 5, 10, 20, 30, 40, 50, 60 or a range between any two of the above.
Alternatively, the theoretical plate number of the product column is independently selected from any of 10, 20, 30, 40, 50, 60, 70, 80 or a range between any two points.
As a specific embodiment, the method for producing benzene by cyclohexane dehydrogenation comprises the following steps:
The production device comprises a raw material heat exchanger, a raw material preheater, a reactor, a condenser, a condensing tank, a deep cooler, a deep cooling tank, a condensate pump, a deep cooling pump, a decanter, a recovery tower, a product tower and a pressurizing pump, and the specific method is as follows:
S01, mixing fresh cyclohexane, air and circulating materials, heating and vaporizing the mixture into superheated steam through a raw material heat exchanger 1, heating the superheated steam to a reaction temperature through a raw material preheater 2, and feeding the superheated steam into a reactor 3;
S02, carrying out oxidative dehydrogenation reaction on the preheated reaction raw materials in a reactor 3 to generate benzene, cyclohexene and water;
s03, cooling the oxidative dehydrogenation reaction product by a reaction raw material through a raw material preheater 2, condensing the cooled product to a lower temperature through a condenser 4, separating the cooled product into gas-liquid two phases, and separating the gas-liquid in a condensing tank 5;
S04, separating the gas phase in the cryogenic tank 7 again after the gas phase obtained in the condensing tank 5 passes through the cryogenic device 6 for cryogenic phase separation to obtain tail gas;
s05, pressurizing liquid phases of the condensation tank 5 and the cryogenic tank 7 through a condensate pump 8 and a cryogenic pump 9 respectively, then delivering the liquid phases into a decanter 10, standing for layering, discharging the obtained water phase which is wastewater from a device, and delivering the oil phase to a recovery tower 11;
S06, a recovery tower 11 obtains non-condensable waste gas and benzene-cyclohexane azeotropic mixture at the tower top through fractional condensation rectification, a liquid phase is sent to a product tower 12, unreacted cyclohexane and cyclohexene which is not completely dehydrogenated are obtained at the tower bottom, and the unreacted cyclohexane and cyclohexene are mixed with fresh raw materials;
S07, obtaining a non-condensable waste gas and benzene-cyclohexane azeotropic mixture at the top of a product tower 12 through fractional condensation and rectification, and returning a liquid phase to a recovery tower 11 for separation to obtain a benzene product at the bottom of the tower.
As a specific embodiment, the process flow of the method for producing unsaturated low-hydrocarbon comprises: a reaction unit and a separation unit. The reaction unit is composed of a circulating flow strand, preheating equipment and a reactor, cyclohexane and air are used as raw materials, and after being mixed with the circulating flow strand, the mixture is heated to the reaction temperature through a heat exchanger and a preheater and subjected to dehydrogenation reaction in the reactor, so that a reaction product containing benzene, cyclohexene and unreacted cyclohexane is obtained. The reaction product is sent to a separation unit consisting of a flash device, a decantation device and a rectification device. The reaction product is subjected to fractional condensation to obtain non-condensable tail gas, the condensate is sent to a decanter, the gravity is used for decanting and layering, fat water is removed, the oil phase is sent to a recovery tower, unreacted cyclohexane and cyclohexene which is not completely dehydrogenated are recovered at the bottom of the tower through azeotropic design, and the cyclic reaction is carried out. The fraction at the top of the recovery tower is sent to a product tower, benzene products are obtained at the bottom of the product tower through azeotropic design, azeotropic mixture of cyclohexene and benzene is obtained at the top of the product tower, and the azeotropic mixture is sent to the recovery tower for separation after being pressurized by a booster pump.
The application has the beneficial effects that:
The method can be used for preparing benzene products by a cyclohexane dehydrogenation method, has continuous process and simple flow, saves high-grade cold energy consumption by fractional condensation, reduces the separation difficulty of azeotropic components by combining gravity decantation, obtains the benzene products by reasonably designing rectification parameters and adopting sequential azeotropic cyclic rectification on the premise of non-total sharp separation, and is suitable for industrialized large-scale continuous operation.
Drawings
FIG. 1 is a schematic diagram of a production apparatus for producing benzene from cyclohexane in an embodiment of the present application.
Wherein:
1. A raw material heat exchanger; 2. a raw material preheater; 3a reactor; 4. a condenser; 5. a condensing tank 6 and a chiller; 7. a cryogenic tank; 8. a condensate pump; 9. a cryogenic pump; 10. a decanter; 11. a recovery tower; 12. a product tower; 13. and a pressurizing pump.
Detailed Description
The present application is described in detail below with reference to examples, but the present application is not limited to these examples.
Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.
Example 1
As shown in FIG. 1, a production device for preparing benzene from cyclohexane comprises the following components:
A raw material heat exchanger 1, a raw material preheater 2, a reactor 3, a condenser 4, a condensing tank 5, a cryocooler 6, a cryotank 7, a condensate pump 8, a cryopump 9, a decanter 10, a recovery tower 11, a product tower 12 and a booster pump 13.
The raw material heat exchanger 1, the raw material preheater 2 and the reactor 3 are sequentially connected, a reaction product outlet I of the reactor 3 is communicated with a reaction product inlet of the raw material heat exchanger 1, and a reaction product outlet II of the raw material heat exchanger 1 is connected with an inlet of the condenser 4.
The outlet of the condenser 4 is connected with a condensing tank 5, and the top gas phase I outlet of the condensing tank 5 is connected with a cryogenic tank 7 through a cryogenic device 6; the bottom of the condensation tank 5 is provided with a condensed liquid phase I outlet, the bottom of the cryogenic tank 7 is provided with a condensed liquid phase II outlet, and the condensed liquid phase I outlet and the condensed liquid phase II outlet are respectively communicated with the decanter 10 through a cryogenic pump 9 and a condensate pump 8; decanter 10 is provided with an aqueous phase outlet and an oil phase outlet; the oil phase outlet is communicated with a recovery tower 11, a gas phase outlet I is arranged at the top of the recovery tower 11, a liquid phase outlet I is arranged on the side wall of the tower, and a cyclohexane II outlet is arranged at the bottom of the tower, wherein the liquid phase outlet I is communicated with a product tower 12, and the cyclohexane II outlet is communicated with a raw material heat exchanger 1; the tower top of the product tower 12 is provided with a gas phase outlet II, the side wall of the tower is provided with a liquid phase outlet II, the tower bottom is provided with a benzene outlet, and the liquid phase outlet II is communicated with the recovery tower 11 through a booster pump 13.
Example 2
By adopting the production device described in the embodiment, the materials containing fresh cyclohexane and recycled unreacted cyclohexane are mixed and then mixed with air according to the mol ratio of 1:7 to obtain a reaction raw material, the reaction raw material is heated to 351 ℃ by a raw material heat exchanger 1 and vaporized into superheated steam, and then the superheated steam is sent into a reactor 3 after being heated to 410 ℃ by a raw material preheater 2, and the oxidative dehydrogenation reaction is carried out at the pressure of 0.13MPaA and the temperature of 410 ℃ to generate a reaction product containing benzene, cyclohexene and water. The reaction product is cooled to 60 ℃ by the reaction raw materials through a raw material preheater 2, condensed to 42 ℃ through a condenser 4, separated into vapor and liquid phases, subjected to vapor-liquid separation under the pressure of 0.12MPaA in a condensing tank 5, subjected to deep cooling to-30 ℃ through a cryogenic refrigerator 6, and subjected to gas-phase separation again in a cryogenic tank 7, wherein the operating pressure of the cryogenic tank 7 is 0.11MPaA, and tail gas is obtained. The liquid phases of the condensation tank 5 and the cryogenic tank 7 are respectively pressurized by a condensate pump 8 and a cryogenic pump 9 and then sent to a decanter 10, and are kept stand and layered at the temperature of 0.6MPaA and the temperature of minus 11 ℃, the obtained water phase is wastewater, the wastewater is discharged out of the device, and the oil phase is sent to a recovery tower 11. The pressure at the bottom of the recovery tower 11 is 0.48MPaA, the temperature at the top of the tower is 42 ℃, 50 theoretical plates are arranged, the reflux ratio is 9, non-condensable waste gas and benzene-cyclohexane azeotropic mixture are obtained at the top of the tower through fractional condensation and rectification, the liquid phase is sent to the product tower 12, unreacted cyclohexane and cyclohexene which is not completely dehydrogenated are obtained at the bottom of the tower, and the unreacted cyclohexane and cyclohexene are mixed with fresh raw materials after circulation. The pressure at the top of the product tower 12 is 50kPaA, the temperature at the top of the tower is 42 ℃, 40 theoretical plates are arranged, the reflux ratio is 5, non-condensable waste gas and benzene-cyclohexane azeotropic mixture are obtained at the top of the tower through fractional condensation and rectification, the liquid phase returns to the recovery tower 11 for separation, and the benzene product with the purity of 99.2%wt is obtained at the bottom of the tower.
While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims (10)

1. A method for producing benzene by cyclohexane dehydrogenation is characterized in that,
(1) Raw materials containing cyclohexane I and air undergo oxidative dehydrogenation reaction to obtain a reaction product containing benzene, cyclohexene and water;
(2) And (3) sequentially obtaining cyclohexane II and benzene after the reaction products are subjected to fractional gas-liquid separation, decantation separation, fractional condensation rectification I and fractional condensation rectification II.
2. The method according to claim 1, wherein,
Step (1) further comprises:
the reaction product exchanges heat with the raw materials;
Preferably, the reaction temperature of the oxidative dehydrogenation reaction is 300-600 ℃ and the reaction pressure is 0.1-3 MPaA.
3. The method according to claim 1, wherein,
The step (2) comprises the following steps:
(a) The reaction product is subjected to fractional condensation to obtain a condensed liquid phase;
(b) Separating the condensed liquid phase by a decanting device to obtain an oil phase and a water phase;
(c) The oil phase is subjected to fractional condensation and rectification I through a recovery tower to obtain a liquid phase I and a mixture containing cyclohexane II;
(d) The liquid phase I is subjected to fractional condensation and rectification II by a product tower to obtain a liquid phase II and benzene;
mixing the liquid phase II with the oil phase in the recovery tower, and repeating the step (3);
Wherein in the step (1), the raw material further comprises the cyclohexane II.
4. The method according to claim 1, wherein,
The grading gas-liquid separation comprises primary gas-liquid condensation and secondary gas-liquid condensation which are sequentially carried out;
the reaction product is subjected to primary gas-liquid cooling to obtain a gas phase I and a condensed liquid phase I;
the gas phase I is subjected to secondary gas-liquid condensation to obtain tail gas and condensed liquid phase II;
Wherein the condensation temperature of the primary gas-liquid condensation is 0-60 ℃ and the condensation pressure is 0.1-3 MPaA;
The condensing temperature of the secondary gas-liquid condensation is-60-0 ℃, and the condensing pressure is 0.1-3 MPaA.
5. The method according to claim 3, wherein,
The operating temperature of the decanting device is-60-0 ℃ and the operating pressure is 0.1-3 MPaA.
6. The method according to claim 3, wherein,
The temperature of the top of the recovery tower is 20-60 ℃, and the operating pressure of the bottom of the recovery tower is 0.1-3 MPaA;
the temperature of the top of the product tower is 20-60 ℃, and the operating pressure of the top of the product tower is 0-500 kPaA.
7. A production device for preparing benzene by cyclohexane dehydrogenation is characterized in that,
The production device comprises an oxidative dehydrogenation reaction unit, a grading gas-liquid separation unit, a decanting device, a recovery tower and a product tower which are sequentially communicated;
The recovery tower and the product tower are rectifying towers;
The bottom of the recovery tower is provided with a mixture outlet containing the cyclohexane II;
And a benzene outlet is arranged at the bottom of the product tower.
8. The apparatus for producing of claim 7, wherein,
The oxidative dehydrogenation reaction unit comprises a heat exchanger, a preheater and an oxidative dehydrogenation reactor which are sequentially communicated;
The reaction product outlet I of the oxidative dehydrogenation reactor is communicated with the reaction product inlet of the heat exchanger; and a dehydrogenation reaction product outlet II of the heat exchanger is communicated with the fractional condensation unit.
9. The apparatus for producing of claim 7, wherein,
The fractional condensation unit comprises a condenser, a condensation tank, a cryocooler and a cryocooler which are sequentially communicated;
the condenser is communicated with the dehydrogenation reaction unit;
The condensing tank is provided with a condensed liquid phase I outlet;
the cryogenic tank is provided with a condensed liquid phase II outlet;
The condensed liquid phase I outlet and the condensed liquid phase II outlet are both communicated with the decanting device;
The cryogenic tank is provided with the tail gas outlet.
10. The apparatus for producing of claim 6, wherein,
The decanting device is provided with an oil phase outlet which is communicated with the recovery tower;
the top of the recovery tower is provided with a gas phase outlet I, the side wall of the recovery tower is provided with a liquid phase outlet I, and the bottom of the recovery tower is provided with a mixture outlet containing cyclohexane II;
the mixture outlet containing the cyclohexane II is communicated with the heat exchanger through a pipeline;
The liquid phase outlet I is communicated with the product tower;
The tower top of the product tower is provided with a gas phase outlet II, the side wall of the tower is provided with a liquid phase outlet II, and the tower bottom is provided with a benzene outlet;
the liquid phase outlet II is communicated with the recovery tower;
Preferably, the reflux ratio of the recovery tower is 1-60, and the theoretical plate number is 10-80;
The reflux ratio of the product tower is 1-60, and the theoretical plate number is 10-80.
CN202211497253.5A 2022-11-25 2022-11-25 Production method and production device for preparing benzene by cyclohexane dehydrogenation Pending CN118084601A (en)

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