High-selectivity cyclohexanol preparation system

Abstract

The utility model provides a system for preparing cyclohexanol with high selectivity, which comprises a hydrogenation reactor, a plurality of strengthening reactors are arranged at the bottom of the hydrogenation reactor, the strengthening reactors are connected through a plurality of channels, and a plurality of stages of fixed reaction beds are arranged at the middle upper part of the hydrogenation reactor; the hydrogenation reactor is connected with the separation device and the rectification device. The system can realize the combined proceeding of hydrogenation reaction and hydration reaction; meanwhile, benzene and cyclohexene can be recycled, and a reinforced reaction unit is combined, so that the reaction efficiency is improved, and the selectivity of cyclohexanol is improved.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering and process technology, and more specifically, to a system for the highly selective preparation of cyclohexanol. Background Technology

[0002] Cyclohexanol is an important organic compound with wide applications. It is a key raw material for the production of various chemical products, including adipic acid, hexamethylenediamine, and cyclohexanone. Cyclohexanol also serves as an organic solvent and plasticizer, among other uses. Existing cyclohexanol preparation processes mainly include phenol hydrogenation, cyclohexane oxidation, and cyclohexene hydration. The phenol hydrogenation method has high raw material costs and high overall costs; the cyclohexane oxidation method suffers from low selectivity, low conversion rate, and poor safety. This invention employs a micro-interface-enhanced method for the hydrogenation and hydration of benzene to produce cyclohexanol, combining the hydrogenation of benzene to produce cyclohexene with the hydration of cyclohexene to produce cyclohexanol. This achieves a 99% selectivity for cyclohexanol production, realizing cost savings and improved product selectivity. In existing benzene hydrogenation reactors, hydrogen gas is initially distributed through a bottom distributor before entering the reactor. The bubble diameter is relatively large, resulting in a small gas-liquid phase interface area. Furthermore, the initially distributed bubbles tend to coalesce and enlarge during their ascent, leading to low gas-liquid mass transfer efficiency and reaction rate.

[0003] In view of the above, this utility model is hereby proposed. Utility Model Content

[0004] The purpose of this invention is to provide a highly selective system for preparing cyclohexanol, which can combine hydrogenation and hydration reactions; at the same time, it can recycle benzene and cyclohexene, and combined with an enhanced reaction unit, it improves reaction efficiency and the selectivity of cyclohexanol.

[0005] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted:

[0006] This invention provides a system for the highly selective preparation of cyclohexanol, comprising: a hydrogenation reactor, wherein multiple enhanced reactors are provided at the bottom of the hydrogenation reactor and the enhanced reactors are connected by multiple channels, and a multi-stage fixed reaction bed is provided in the middle and upper part of the hydrogenation reactor; the hydrogenation reactor is connected to a separation device and a distillation device.

[0007] The hydrogenation reactor incorporates multiple enhanced reactors, the number of which can be adjusted according to actual needs. All enhanced reactors are pneumatically operated to convert the reactants into microbubbles. Channels connect each enhanced reactor; these channels can be perpendicular or non-parallel, depending on the requirements. These channels concentrate the reactants, enabling more efficient mixing and significantly increasing the reaction rate.

[0008] The reaction bed can be a fixed reaction bed, or a suspended bed or slurry bed reactor can be selected to replace the fixed reaction bed depending on the size of the catalyst. After hydrogenation, the set separation and distillation units can better separate the substances and allow the reactants to be recycled.

[0009] Preferably, as a further specific embodiment, a diffusion tube is provided between the enhanced reactor and the multi-stage fixed reaction bed, and the inclination angle of the diffusion tube wall is 4°-5°.

[0010] By placing the catalyst in a fixed bed for the reaction, there is no need for an additional separation device to separate the catalyst from the reactants. Simultaneously, the diffuser further concentrates the reactants, which is more conducive to improving reaction efficiency. The inclination angle of the diffuser wall is set to 4°-5°. If the inclination angle is too small, the diffuser is almost vertical, which cannot effectively slow down the reaction and ensure thorough mixing of the reactants. If the inclination angle is too large, it will inevitably shorten the distance between the diffuser and the reactor, thus reducing the reaction distance. Therefore, a diffuser wall inclination angle of 4°-5° is beneficial for reducing the rate at which reactants enter the fixed bed, allowing the reactants to fully contact the catalyst, reducing the occurrence of side reactions, and improving reaction efficiency.

[0011] Preferably, as a further specific embodiment, the separation device includes a gas-liquid separation tower, which has two separators inside and an inlet in the middle of the two separators. The gas-liquid separation tower is directly connected to the hydrogenation reactor through the inlet.

[0012] The hydrogen separated at the top of the gas-liquid separator is recycled through a hydrogenation reactor, while the liquid material is pumped into a hydration reactor for hydration, thus achieving material recycling. An inlet is located between the two separators to ensure gas-liquid separation; however, the separation efficiency of a single separator may be reduced. Simultaneously, the separator can separate hydrogen from the products, which can then re-enter the reaction system, achieving hydrogen reuse.

[0013] Preferably, as a further specific embodiment, the separation device includes a hydration reactor, and the gas-liquid separation tower is directly connected to the hydration reactor via a circulating pump; the bottom of the hydration reactor is provided with multiple enhanced reactors, which are connected to each other through multiple channels, and the upper middle part of the hydration reactor is provided with multiple fixed reaction beds.

[0014] The setup inside the hydration reactor is basically the same as the internal structure of the hydrogenation reactor, so that after the material enters the hydration reactor, the reactants flow from bottom to top. By strengthening the reactor unit and the pipeline setup, the efficiency of the hydration reaction is improved and the occurrence of side reactions is reduced.

[0015] Preferably, as a further specific embodiment, the separation device further includes an oil-water separator, which is used to connect the gas-liquid separation tower and the distillation device; the bottom of the oil-water separator is provided with a pipeline connected to the upstream of the circulating pump.

[0016] Preferably, as a further specific embodiment, the distillation apparatus includes distillation column a and distillation column b, both of which have condensers connected in parallel at their tops and reboilers connected in parallel at their bottoms; the condenser connected in parallel with distillation column b is connected to a liquid inlet located at the bottom of the hydrogenation reactor, and the reboiler connected in parallel with distillation column b is connected upstream of the circulating pump.

[0017] The setup of water-oil separators and multiple distillation columns can better separate cyclohexanol, cyclohexene, cyclohexane, and benzene. A single distillation cannot separate these substances in one go, or may result in incomplete separation, thereby reducing the purity of the product.

[0018] Preferably, as a further specific embodiment, the top of the gas-liquid separation tower is provided with an outlet, which is connected to the gas inlet of the hydrogenation reactor via a pipeline.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] The hydrogenation reactor of this invention adopts a fixed-bed reactor, which can realize the combined hydrogenation reaction and hydration reaction; at the same time, it can recycle benzene and cyclohexene, and combined with the enhanced reaction unit, it improves the reaction efficiency and the selectivity of cyclohexanol. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0022] Figure 1 Schematic diagram of an enhanced apparatus for the highly selective preparation of cyclohexanol.

[0023] The markings in the attached figure are as follows:

[0024] 1. Hydrogen inlet; 2. Benzene and oxygen-free water inlet; 3. Hydrogenation reactor; 4. Gas-liquid separation tower;

[0025] 5. Hydration reactor; 6. Oil-water separator; 7. Distillation column a; 8. Distillation column b; 9. Reboiler;

[0026] 10. Cyclohexane outlet; 11. Fixed reaction bed; 12. Fixed reaction bed; 13. Enhanced reactor;

[0027] 14. Enhanced reactor; 15. Separator; 16. Separator; 17. Fixed reaction bed;

[0028] 18. Fixed reaction bed; 19. Enhanced reactor; 20. Enhanced reactor; 21. Circulating pump;

[0029] 22. Condenser; 23. Condenser; 24. Reboiler; 25. Channel; 26. Diffuser; 27. Channel. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] To more clearly illustrate the technical solutions in this invention, specific embodiments are described below.

[0034] Example

[0035] like Figure 1 The connection method is shown. In this invention, a hydrogenation reactor 3 is provided, and at the bottom of the hydrogenation reactor 3, an enhanced reactor 14 and an enhanced reactor 13 are provided. Both enhanced reactors 14 and 13 are pneumatic enhanced reaction devices, and they are connected through a channel 25. A fixed reaction bed 12 and a fixed reaction bed 13 are provided at the top of the hydrogenation reactor 3. Both fixed reaction beds are lined with a ruthenium-zinc catalyst. A diffuser 26 is provided on the enhanced reactor 13 and connected to the fixed reaction bed 12. The inclination angle of the diffuser 26 is 4°-5°. A hydrogen inlet 14 is provided in the hydrogenation reactor 3 at a position corresponding to the enhanced reactor 14, and a benzene and oxygen-free water inlet 2 is provided at the bottom of the hydrogenation reactor 3.

[0036] The hydrogenation reactor 3 is connected to the gas-liquid separation tower 4, which contains separators 15 and 16. A pipeline is installed at the top of the hydrogenation reactor 3, with one end connected to the reactor and the other end connected to the gas-liquid separation tower 4. The connection point between the pipeline and the gas-liquid separation tower 4 is located between separators 15 and 16. Additionally, a pipeline is installed at the top of the gas-liquid separation tower 4, which is also connected to the pipeline of the hydrogen inlet 1.

[0037] A pipeline is installed at the bottom of the gas-liquid separator 4, which is connected to the bottom of the hydration reactor 5 via a circulating pump 21. At the bottom of the hydration reactor 5 are two enhanced reactors, 19 and 20, both pneumatically operated, with a channel 27 connecting them. Fixed reaction beds 17 and 18 are installed at the top of the hydration reactor 5. A pipeline outlet at the top of the hydration reactor 5 connects to the oil-water separator 6. A pipeline outlet at the bottom of the oil-water separator 6 connects to the upstream end of the pipeline containing the circulating pump 21.

[0038] Oil-water separator 6 is sequentially connected to distillation column a7 and distillation column b8. Condensers 22 and 23 are connected in parallel at the top of distillation columns a7 and b8, respectively, and reboilers 9 and 24 are connected in parallel at the bottom, respectively. Distillation column b8 also has a cyclohexane outlet in its middle section. Reboiler 24 is also connected to benzene and oxygen-free water inlet 2 via piping, and condenser 23 is connected to the upstream of the piping containing circulating pump 21.

[0039] Work mode:

[0040] Ruthenium-zinc catalyst is loaded into fixed beds 12 and 11 of hydrogenation reactor 3. Benzene, hydrogen, and water in a molar ratio of 6:5:3 are introduced into enhanced reactor 14 through hydrogen inlet 1 and benzene and oxygen-free water inlet 2, respectively. The reactants enter enhanced reactor 13 through channel 25 between the two reactors, and then react with the ruthenium-zinc catalyst packed in fixed beds 12 and 11 through diffuser 26 at a reaction pressure of 4.0 MPa-5.0 MPa and a reaction temperature of 130℃-145℃ to produce cyclohexene.

[0041] The generated cyclohexene flows from the top of the hydrogenation reactor 3 into the gas-liquid separation tower 4. The separated hydrogen gas enters the hydrogenation reactor 3 again through a pipe at the top of the gas-liquid separation tower 4 for recycling. The liquid material enters the hydration reactor 5 through a pipe at the bottom of the gas-liquid separation tower 4 and simultaneously through a circulation pump 21. Crystalline molecular sieve catalyst SiO2 / Al2O3 is fixed on the fixed reaction beds 17 and 18 in the hydration reactor 5. The liquid material enters from the bottom of the hydration reactor 5 and moves upward continuously. After initial crushing in the intensified reactor 20, it enters the intensified reactor 19 through channel 27, forming a micro-interface system before continuing to move upward. It then passes through the catalysts in the fixed reaction beds 18 and 19, and undergoes cyclohexene hydration to produce cyclohexanol at a reaction pressure of 0.5 MPa-0.6 MPa and a reaction temperature of 115℃-120℃. Because the hydration reaction is relatively slow, no additional diffusion tube is needed to enhance the reaction.

[0042] The material after hydration reaction enters the oil-water separator 6 from the hydration reactor 5 and is left to stand for separation. The water flows out of the oil-water separator 6 and is circulated back into the hydration reactor 5 through pipelines for reuse. The oil phase is fed into the distillation column for distillation separation.

[0043] The oil phase undergoes two distillations in distillation columns a7 and b8. The initial distillation in column a7 yields cyclohexanol. The remaining oil phase enters column b8, where the separated cyclohexene can be recycled back into the hydration reactor 5 via the upstream pipeline of the circulating pump 21. The separated benzene can be reintroduced into the reaction system through the benzene and deoxygenated water inlet 2 for further reaction. During the reaction, reboilers 9 and 24 revaporize the oil phase, reducing energy consumption and facilitating energy reuse. Condensers 22 and 23 rapidly convert the vaporized oil phase into a liquid phase and provide timely heat dissipation for the system.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for the production of cyclohexanol with high selectivity, characterized in that, The application relates to a hydrogenation reactor, which comprises the following parts: A hydrogenation reactor, the bottom of which is provided with a plurality of reinforced reactors connected by a plurality of channels, and the middle and upper part of the hydrogenation reactor is provided with a plurality of fixed reaction beds; the hydrogenation reactor is connected with a separation device and a rectification device.

2. The system for the production of cyclohexanol with high selectivity according to claim 1, characterized in that, A diffusion pipe is arranged between the reinforced reactor and the fixed reaction bed, and the inclined angle of the pipe wall is 4-5 degrees.

3. The system for the production of cyclohexanol with high selectivity according to claim 1, characterized in that, The separation device comprises a gas-liquid separation tower, the inside of which is provided with two separators, the middle of which is provided with an inlet, and the gas-liquid separation tower is directly connected with the hydrogenation reactor through the inlet.

4. The system for the production of cyclohexanol with high selectivity according to claim 3, characterized in that, The separation device comprises a hydration reactor, and the gas-liquid separation tower is directly connected with the hydration reactor through a circulating pump; the bottom of the hydration reactor is provided with a plurality of reinforced reactors connected by a plurality of channels, and the middle and upper part of the hydration reactor is provided with a plurality of fixed reaction beds.

5. The system for the production of cyclohexanol with high selectivity according to claim 4, characterized in that, The separation device further comprises an oil-water separation tank, which is used for connecting the gas-liquid separation tower and the rectification device; the bottom of the oil-water separation tank is provided with a pipeline connected with the upstream of the circulating pump.

6. The system for the production of cyclohexanol with high selectivity according to claim 4, characterized in that, The rectification device comprises rectification tower a and rectification tower b, the top of each of the rectification tower a and the rectification tower b is connected with a condenser in parallel, and the bottom of each of the rectification tower a and the rectification tower b is connected with a reboiler in parallel; the condenser connected with the rectification tower b is connected with a liquid inlet arranged at the bottom of the hydrogenation reactor, and the reboiler connected with the rectification tower b is connected with the upstream of the circulating pump.

7. The system for the production of cyclohexanol with high selectivity according to claim 3, characterized in that, The top of the gas-liquid separation tower is provided with an outlet connected with a gas inlet of the hydrogenation reactor through a pipeline. The application relates to a hydrogenation reactor, which comprises the following parts:

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