Process for the selective hydrogenation of benzene

Abstract

The application discloses a benzene selective hydrogenation reactor and a benzene selective hydrogenation reaction method. The reactor comprises a reaction kettle, a feeding pipeline, a stirring device, an insulation jacket, a deceleration plate, a slurry backflow pipeline, a product outlet and an exhaust pipeline. The deceleration plate is arranged in the reaction kettle and divides the reaction kettle into a lower reaction zone and an upper settling zone. The deceleration plate is provided with a deceleration channel, and the lower reaction zone and the upper settling zone are communicated through the deceleration channel. The stirring device is provided with a stirring element, and the stirring element is arranged in the lower reaction zone. The slurry backflow pipeline is arranged outside the reaction kettle, one end of the slurry backflow pipeline is connected with a liquid outlet of the upper settling zone, and the other end of the slurry backflow pipeline is connected with a liquid return port of the lower reaction zone. The product outlet is arranged in the upper settling zone and is higher than the liquid outlet. The exhaust pipeline is arranged at the upper portion of the reaction kettle. The benzene selective hydrogenation reactor and the benzene selective hydrogenation reaction method have improved cyclohexene selectivity.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a benzene selective hydrogenation reactor and a benzene selective hydrogenation reaction method. Background Technology

[0002] Cyclohexene is an important organic chemical raw material with wide applications in the synthesis of pharmaceuticals and fine chemicals, its most important application being the production of synthetic fibers. Cyclohexene can be directly hydrated to produce cyclohexanol, directly oxidized to produce adipic acid, or dehydrogenated from cyclohexanol to produce cyclohexanone, which then undergoes a series of reactions to generate caprolactam. Compared to the traditional route of selective hydrogenation of benzene to produce cyclohexane, which is then catalytically oxidized to a mixture of cyclohexanol and cyclohexanone, the cyclohexene route shortens the production process of nylon-66 and caprolactam, has a high single-pass conversion rate, fewer byproducts, and is more energy-efficient and environmentally friendly. Currently, the selective hydrogenation of benzene to produce cyclohexene has enormous industrial production potential.

[0003] In 1988, Asahi Kasei Corporation of Japan built the world's first plant for the selective production of cyclohexene from benzene. To change Japan's monopoly, by the late 1990s, my country had made significant progress in the research of selective hydrogenation catalysts and industrial-scale equipment for benzene, as evidenced by patents such as CN 1176886C, CN 1597098A, CN 1714932A, CN 1696087A, CN 105056943A, CN 101850225A, CN 102600841A, CN 102744085A, and CN 105126839A.

[0004] The hydrogenation of benzene is a gas-liquid reaction carried out in a high-pressure autoclave reactor. Existing Ru-based catalyst systems typically require the addition of ZnSO4 aqueous solution to ensure high selectivity for cyclohexene. The subsequent separation of the aqueous slurry containing zinc sulfate and catalyst from the oil-phase product cyclohexene is a crucial performance indicator. Currently reported benzene selective hydrogenation units, such as CN 1696087A and CN101850225A, achieve this separation by adding additional settling tanks or separators. Cyclohexene selectivity is a key performance indicator. In traditional reactors, due to the complex separation process, the aqueous slurry and oil-phase product are prone to backmixing, causing cyclohexene to re-contact the catalyst in the aqueous slurry and undergo hydrogenation to form cyclohexane, resulting in reduced cyclohexene selectivity. Furthermore, adding additional tanks inevitably increases costs and complicates the operation. Therefore, simplifying the separation process, further improving cyclohexene selectivity, and reducing equipment costs and maintenance difficulty would represent a significant advancement in the industrial-scale selective hydrogenation of benzene and have broad application prospects. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a novel benzene selective hydrogenation reactor and a benzene selective hydrogenation reaction method, which can achieve integrated reaction and separation.

[0006] In a first aspect, the present invention provides a benzene selective hydrogenation reactor, the reactor comprising: a reaction vessel, a feed pipe, a stirring device, a heat-insulating jacket, a speed reduction plate, a slurry reflux pipe, a product outlet, and an exhaust pipe, wherein...

[0007] The speed reduction plate is installed inside the reactor and divides the reactor into a lower reaction zone and an upper settling zone. The speed reduction plate is provided with a speed reduction channel, especially a speed reduction channel with a diameter that decreases from bottom to top. The lower reaction zone and the upper settling zone are connected through the speed reduction channel.

[0008] One end of the feed pipe is located outside the reactor, and the other end extends into the lower reaction zone;

[0009] The stirring device is equipped with a stirring element, which is disposed within the lower reaction zone;

[0010] The heat-insulating jacket is disposed on the outside of the reactor and surrounds at least a portion of the reactor;

[0011] The slurry return pipe is located outside the reactor, with one end connected to the outlet of the upper settling zone and the other end connected to the return port of the lower reaction zone.

[0012] The product outlet is located in the upper settling zone and is higher than the liquid outlet;

[0013] The exhaust pipe is located at the top of the reactor.

[0014] The benzene selective hydrogenation reactor provided by the present invention can be any known reactor in the art. Typically, the reactor comprises a reactor body and a fitted sealing cap.

[0015] According to the benzene selective hydrogenation reactor provided by the present invention, the feed pipeline includes a gas inlet pipeline and a benzene inlet pipeline.

[0016] In this invention, one end of the gas inlet pipe and the benzene inlet pipe extends into the bottom of the lower reaction zone and the opening faces downward or toward the stirring element. This facilitates uniform mixing of materials.

[0017] In this invention, the gas inlet pipe and the benzene inlet pipe are respectively equipped with a flow meter and a flow regulating valve to regulate the flow rate of the gas and benzene.

[0018] According to the benzene selective hydrogenation reactor provided by the present invention, the deceleration plate is provided with a plurality of deceleration channels, the density of which gradually decreases from the center to the edge. With this arrangement, when the slurry (or liquid) vortex is generated by stirring in the lower reaction zone, the velocity of the slurry (or liquid) is faster at the edges and relatively slower in the center. This ensures that after the slurry passes through the deceleration plate, the overall liquid level rise rate (flux) can tend to be uniform, resulting in a smooth liquid level rise.

[0019] In some embodiments, the spacing of the outermost deceleration channels of the deceleration plate is 1.5 to 10 times the spacing of the central deceleration channels, for example, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10 or any value between them, preferably 1.5 to 5 times.

[0020] According to the benzene selective hydrogenation reactor provided by the present invention, the diameter of the deceleration channel in the deceleration plate is 0.1cm-30cm, preferably 0.1cm-10cm.

[0021] According to the benzene selective hydrogenation reactor provided by the present invention, the aperture of the deceleration channel on the lower surface of the deceleration plate is 2-50 times the aperture of the upper surface, for example, 2, 3, 4, 5, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50 or any value between them, preferably 2-20 times.

[0022] According to the benzene selective hydrogenation reactor provided by the present invention, the deceleration plate includes multiple layers of deceleration plate elements, each layer of the deceleration plate element is provided with a plurality of through holes, and the through holes of the multiple layers of deceleration plate elements are connected to form the deceleration channel.

[0023] According to the benzene selective hydrogenation reactor provided by the present invention, the material of the speed reducer and the speed reducer element is independently stainless steel mesh, porous ceramic material or thin film.

[0024] According to the benzene selective hydrogenation reactor provided by the present invention, a plurality of limiting screws for installing the speed reduction plate are provided on the side wall of the reactor to install the speed reduction plate at different heights. Furthermore, the water-oil interface can be adjusted by changing the placement position of the speed reduction plate, ultimately ensuring that the static liquid level is higher than the speed reduction plate.

[0025] In some implementations, the speed brake is installed at 1 / 2 to 2 / 3 of its height.

[0026] According to the benzene selective hydrogenation reactor provided by the present invention, the slurry reflux pipeline includes a main reflux pipeline and an auxiliary reflux pipeline arranged in parallel, and the auxiliary reflux pipeline is equipped with a pump and a switching valve. The main reflux pipeline can reflux naturally by relying on potential energy difference, while the reflux rate of the auxiliary reflux pipeline can be controlled by the pump and the switching valve.

[0027] According to the benzene selective hydrogenation reactor provided by the present invention, the stirring element is disposed on the lower side of the lower reaction zone, preferably horizontally aligned with the return liquid port. In the present invention, the stirring element can be blade-shaped or rod-shaped, and its rotation ensures sufficient contact between the reactants and the catalyst in the reaction system.

[0028] In some embodiments, the stirring device is a mechanical stirrer, with one end of its stirring rod mounted on a sealing cover, the stirring rod extending through a speed reduction plate, and the other end provided with a blade-shaped or rod-shaped stirring element.

[0029] According to the benzene selective hydrogenation reactor provided by the present invention, a pressure gauge and a pressure regulating valve are provided on the exhaust pipe.

[0030] According to the benzene selective hydrogenation reactor provided by the present invention, a heat exchange medium is circulated within the insulation jacket. The present invention does not have special requirements for the heat exchange medium; any heat exchange medium known in the art can be used.

[0031] Secondly, the present invention provides a method for selective hydrogenation of benzene, characterized in that the method is carried out using the selective hydrogenation reactor of the present invention.

[0032] The selective hydrogenation reaction method for benzene provided by the present invention includes the following steps:

[0033] 1) Prepare a reaction slurry comprising catalyst, water and zinc sulfate and add it to the benzene selective hydrogenation reactor;

[0034] 2) Introduce an inert gas, such as nitrogen, to replace the air in the benzene selective hydrogenation reactor, and then add benzene;

[0035] 3) Heat the benzene selective hydrogenation reactor to 100-200°C, preferably 130-160°C, and introduce hydrogen gas to carry out the reaction. Preferably, the hydrogen gas pressure is controlled at 4-5 MPa.

[0036] 4) Obtain the target product from the product export.

[0037] According to the selective hydrogenation reaction method for benzene provided by the present invention, the average flow rate of benzene is 30-60 kg / h, preferably 30-40 kg / h; and / or the circulation rate of the reaction slurry is 60-160 kg / h, preferably 60-70 kg / h.

[0038] According to the selective hydrogenation reaction method for benzene provided by the present invention, the reaction in step 3) is carried out at a rotation speed of 200-600 r / min, preferably 300-500 r / min.

[0039] According to the selective hydrogenation method for benzene provided by the present invention, the catalyst is selected from metal-modified ZrO2 catalysts, SiO2 catalysts, and Al2O3-based catalysts, and / or the mass ratio of the catalyst, water, and zinc sulfate is 1:(50-500):(0-80). For example, the mass ratio of the catalyst to water can be 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1:120, 1:140, 1:160, 1:200, 1:240, 1:280, 1:300, 1:350, 1:400, 1:500, or any value between them. For example, the mass ratio of catalyst to zinc sulfate can be 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:60, 1:70, 1:80, or any value between them. In some embodiments, the mass ratio of catalyst, water, and zinc sulfate is 1:(50-500):(10-80).

[0040] According to the selective hydrogenation method for benzene provided by the present invention, the reaction slurry further includes an additive selected from one or more of 1,3-propanediol, polyethylene glycol, ethylene glycol, ethanolamine, diethanolamine, diphenylamine, ethylenediamine, and diethylamine. In this invention, the number average molecular weight of the suitable polyethylene glycol can be 700-6000 g / mol. In some embodiments, the additive comprises 1,3-propanediol, ethylene glycol, and monoethanolamine in a mass ratio of (1.5-2.5):(4-6):1.

[0041] When used, the additive is applied at a concentration of 0.01%-10% of the water mass. For example, the additive concentration can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value between these concentrations. In some embodiments, the additive concentration can be 0.01%-4% of the water mass.

[0042] All of the above-mentioned raw materials used in this invention can be prepared in-house or purchased commercially; this invention does not impose any particular limitations on them.

[0043] This invention has the following advantages:

[0044] 1) For existing reactors, the separation of slurry and product requires an additional settling tank or separation tank. However, the benzene selective hydrogenation reactor of the present invention, by setting a speed reduction plate and other matching structures, enables the separation function to be completed simultaneously in the upper part of the reactor.

[0045] 2) The slurry return pipeline can make full use of the potential energy difference, which greatly reduces the energy consumption required for the slurry return process;

[0046] 3) The benzene selective hydrogenation reactor of the present invention exhibits higher cyclohexene selectivity than conventional reaction devices;

[0047] 4) The benzene selective hydrogenation reactor of the present invention can reduce the number of reactors, eliminate the need for additional settlers or separation tanks, and greatly reduce investment costs and simplify the operation of the equipment by simplifying the process flow. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of one embodiment of the benzene selective hydrogenation reactor according to the present invention;

[0049] Figure 2 This is a bottom view of the deceleration plate in the benzene selective hydrogenation reactor according to the present invention;

[0050] Among them, 1-gas inlet pipe, 2-benzene inlet pipe, 3-sealing cover, 4-stirring device, 5-insulation jacket, 6-speed reducer, 7-slurry return pipe, 8-product outlet, and 9-exhaust pipe. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0052] This invention provides a benzene selective hydrogenation reactor.

[0053] Reference Figure 1 The benzene selective hydrogenation reactor of the present invention includes a reaction vessel, a feed pipe, a stirring device 4, a heat insulation jacket 5, a speed reduction plate 6, a slurry return pipe 7, a product outlet 8, and an exhaust pipe 9.

[0054] The reactor is a Hastelloy high-pressure reactor, consisting of a reactor body and a matching sealing cover 3.

[0055] A speed reduction plate 6 is installed inside the reactor, dividing the reactor into a lower reaction zone and an upper settling zone. The speed reduction plate 6 is provided with a speed reduction channel whose aperture decreases from bottom to top, and the lower reaction zone and the upper settling zone are connected through the speed reduction channel.

[0056] The density of the deceleration channels gradually decreases from the center to the edge. This arrangement ensures that when the slurry (or liquid) vortex is generated in the lower reaction zone, the velocity of the slurry (or liquid) is faster at the edges and relatively slower in the center. This guarantees that the overall liquid surface rise rate (flux) is more consistent after passing through the deceleration plate, resulting in a smoother rise. The spacing of the outermost deceleration channels of the deceleration plate 6 can be 1.2-5 times the spacing of the central deceleration channels, for example, 1.2, 1.5, 2, 3, 4, 5, or any value between them. Figure 2 In the implementation scheme shown, the spacing between the outermost two rows of deceleration channels is three times the average spacing between the two central rows of deceleration channels.

[0057] The deceleration channel diameter of the deceleration plate 6 is 0.1cm-30cm, preferably 0.1cm-10cm. The deceleration plate 6 includes multiple layers of deceleration plate elements, each layer of which has several through holes. The through holes of the multiple layers of deceleration plate elements are connected to form a deceleration channel. When the deceleration plate 6 is composed of multiple layers of deceleration plate elements, the deceleration channels from the bottom layer to the top layer are successively the first channel, the second channel, the third channel, etc., and the diameter of the channels gradually decreases. When the liquid (slurry) passes through the first channel, it is separated into several water flows by several first channels, and then flows to the second channel. Since the diameter of the second channel is smaller than that of the first channel, part of the water flow is blocked, and the other part of the water flow passes through the second channel. The same applies when it flows to the third channel, and so on, reducing the flow rate of liquid passing through the deceleration plate 6 in the same amount of time. The diameter of the deceleration channel gradually decreases from bottom to top, so that when the liquid at the bottom passes upward, its flow velocity gradually weakens until it stops. The liquid above the deceleration plate 6 achieves stratification of the product and the reaction slurry.

[0058] The speed reducer 6 and its components are each made of stainless steel mesh, porous ceramic material, or thin film. Several limiting screws are provided on the side wall of the reactor for mounting the speed reducer, allowing it to be installed at different heights. The speed reducer 6 is installed at 1 / 2 to 2 / 3 of its height. Furthermore, the water-oil interface can be adjusted by changing the placement of the speed reducer 6, ultimately ensuring that the level of the static liquid is higher than that of the speed reducer 6.

[0059] The stirring device 4 is equipped with a stirring element, which is located in the lower reaction zone. The stirring element can be blade-shaped or rod-shaped, and its rotation ensures sufficient contact between the reactants and the catalyst in the reaction system.

[0060] One end of the feed pipe is located outside the reactor, and the other end extends into the lower reaction zone. Specifically, the feed pipe includes a gas inlet pipe 1 and a benzene inlet pipe 2. One end of the gas inlet pipe 1 and the benzene inlet pipe 2 extends into the bottom of the lower reaction zone and opens downwards or toward the stirring element. Flow meters and flow regulating valves are respectively installed on the gas inlet pipe 1 and the benzene inlet pipe 2 to regulate the flow rates of the gas and benzene.

[0061] The insulation jacket 5 is set outside the reactor and surrounds the reactor; the insulation jacket 5 can be filled with heat exchange medium, including water, steam or heat transfer oil, etc., which can be adjusted according to the reaction conditions.

[0062] The slurry reflux pipe 7 is located outside the reactor, with one end connected to the outlet of the upper settling zone and the other end connected to the reflux port of the lower reaction zone. The outlet is located above the deceleration plate 6 and below the surface of the stationary liquid above the deceleration plate 6. The slurry reflux pipe includes a main reflux pipe and an auxiliary reflux pipe connected in parallel. The main reflux pipe can be equipped with a flow meter and a flow regulating valve, while the auxiliary reflux pipe is equipped with a pump and a switching valve. The main reflux pipe can naturally reflux due to potential energy difference, and its flow rate can be controlled by the flow regulating valve. The reflux rate of the auxiliary reflux pipe can be controlled by the pump and the switching valve. In particular, if a higher flow rate is required, the switching valve can be opened to allow the slurry to reflux back to the lower reaction zone through the auxiliary reflux pipe.

[0063] Product outlet 8 is located in the upper settling zone and is higher than the liquid outlet.

[0064] The exhaust pipe 9 is located at the top of the reactor, particularly on the sealing cover 3, and is equipped with a pressure gauge and a pressure regulating valve. The pressure in the reactor can be adjusted by regulating the gas discharge.

[0065] The working principle of the device of the present invention is as follows:

[0066] After the reaction slurry prepared with catalyst, water and zinc sulfate is added to the benzene selective hydrogenation reactor, the sealing cap 3 is sealed. A certain amount of nitrogen gas is introduced through the gas inlet pipe 1 to replace the air in the reactor, and then a certain amount of benzene is introduced through the benzene inlet pipe 2. The stirring device 4 is turned on and a certain speed is set. At the same time, the temperature is raised through the heat insulation jacket 5. After the temperature stabilizes, a certain amount of hydrogen gas is introduced through the gas inlet pipe 1, and the flow rate is controlled to maintain the pressure. The reaction is carried out for a certain period of time. The rotation of the blades of the stirring device 4 will cause obvious flow of liquid at the bottom of the reactor. The reactor is equipped with a speed reduction plate 6. After the slurry in the lower reaction zone passes through the speed reduction plate 6, its flow rate gradually decreases until it stops. It achieves stratification in the upper settling zone. The upper layer is a mixture of oil phase cyclohexene and benzene, which is extracted from the product outlet 8. The lower layer is the reaction slurry, which is returned to the lower reaction zone through the slurry return pipe 7. Temperature regulation can be achieved by controlling the medium parameters of the insulation jacket 5; gas emission can be controlled by adjusting the pressure regulating valve on the exhaust pipe 9 to achieve pressure regulation in the reactor; and the liquid level and oil-water interface in the reactor can be regulated by adjusting the position of the deceleration plate 6.

[0067] Example 1

[0068] The reactor is heated to 140°C by the heat exchange medium (steam) inside the insulation jacket 5, the reaction pressure is set to 5.0MPa, and the rotation speed is 300r / min; the deceleration plate 6 is made of 5 layers of stainless steel mesh with mesh counts of 20, 50, 100, 150 and 200 from bottom to top, and is placed at 2 / 3 of the height of the reactor.

[0069] The specific operation process is as follows: After adding the reaction slurry prepared by Ru-Zn / ZrO2 catalyst, water and zinc sulfate (mass ratio 1:140:25) to the reactor, seal the sealing cap 3, introduce nitrogen gas through gas inlet pipe 1 to replace the air in the reactor, and then introduce benzene gas through benzene inlet pipe 2. The average benzene flow rate is 55.4 kg / h, and the slurry circulation rate is 153.6 kg / h. Turn on the stirring device 4, set the speed to 300 r / min, and heat the reactor to 140℃ through the heat insulation jacket 5. After the temperature stabilizes, introduce hydrogen gas through gas inlet pipe 1, and control the flow rate to maintain the pressure at 5.0 MPa.

[0070] In this embodiment, a distinct stratification is formed in the upper settling zone. After the reaction, the product flows out from product outlet 8 and is measured. When the benzene conversion rate is 50.6%, the cyclohexene selectivity is 74.6%.

[0071] Example 2

[0072] In this embodiment, the speed reducer 6 is made of 5 layers of stainless steel mesh, with mesh counts from bottom to top being 100 mesh, 120 mesh, 200 mesh, 240 mesh and 300 mesh, and the average benzene flow rate is 54.5 kg / h. All other conditions are the same as in Example 1.

[0073] In this embodiment, a distinct stratification is formed in the upper settling zone, and the cyclohexene selectivity is 66.5% when the benzene conversion rate is 51.3%.

[0074] Comparative Example 1

[0075] Comparative Example 1 did not use the multi-layer stainless steel mesh speed reducer 6, and the average benzene flow rate was 53.6 kg / h. All other conditions were the same as in Example 1. After 30 min of reaction, the cyclohexene selectivity was 60.2% when the benzene conversion rate was 50.0%.

[0076] Example 3

[0077] The reactor is heated to 150°C by the heat exchange medium (heat transfer oil) inside the insulation jacket 5, the reaction pressure is set to 4.5MPa, and the rotation speed is 400r / min; the deceleration plate 6 is made of porous ceramic material with an average pore diameter of 2cm, the pores of the porous ceramic material are evenly distributed, the thickness is 10cm, and it is placed at 1 / 2 height of the reactor.

[0078] The specific operation process is as follows: After adding the reaction slurry prepared by Ru-Zn / Al2O3 catalyst, water and zinc sulfate (mass ratio 1:100:20) to the reactor, seal the sealing cap 3, introduce a certain amount of nitrogen gas through the gas inlet pipe 1 to replace the air in the reactor, and then introduce benzene gas through the benzene inlet pipe 2. The average benzene flow rate is 34.1 kg / h, and the slurry circulation rate is 68.4 kg / h. Turn on the stirring device 4, set the speed to 400 r / min, and heat the reactor to 140℃ through the heat insulation jacket 5. After the temperature stabilizes, introduce hydrogen gas through the gas inlet pipe 1, and control the flow rate to maintain the pressure at 4.5 MPa.

[0079] In this embodiment, a distinct stratification is formed in the upper settling zone. After the reaction, the product flows out from product outlet 8 and is measured. When the benzene conversion rate is 50.1%, the cyclohexene selectivity is 79.7%.

[0080] Comparative Example 2

[0081] Comparative Example 2 did not use the porous ceramic material deceleration plate 6, and the average benzene flow rate was 35.4 kg / h. All other conditions were the same as in Example 3. After 30 min of reaction, the cyclohexene selectivity was 66.5% at a benzene conversion rate of 50.4%.

[0082] Comparative Example 3

[0083] Comparative Example 3 used a porous ceramic material speed reducer 6 with an average pore size of 15 cm and an average benzene flow rate of 33.9 kg / h. All other conditions were the same as in Example 3. No obvious oil-water separation interface was observed during the experiment.

[0084] Example 4

[0085] In this embodiment, the deceleration plate 6 is made of porous ceramic material. The spacing between the outermost two rows of mesh holes is three times the average spacing between the middle two rows of mesh holes, and the thickness is 10cm. All other conditions are the same as in Embodiment 1.

[0086] A distinct stratification is formed in the upper settling zone. After the reaction, the product flows out from product outlet 8. Measurements show that the cyclohexene selectivity is 80.6% when the benzene conversion rate is 50.2%.

[0087] Example 5

[0088] The reactor is heated to 140°C by the heat exchange medium (steam) inside the insulation jacket 5, the reaction pressure is set to 5.0MPa, and the rotation speed is 300r / min; the deceleration plate 6 is made of 5 layers of stainless steel mesh with mesh counts of 20, 50, 100, 150 and 200 from bottom to top, and is placed at 2 / 3 of the height of the reactor.

[0089] The specific operation process is as follows: A reaction slurry is prepared by mixing Ru-Zn / ZrO2 catalyst, water, zinc sulfate, and additives (1,3-propanediol, ethylene glycol, and monoethanolamine in a mass ratio of 2:5:1), wherein the mass ratio of Ru-Zn / ZrO2 catalyst, zinc sulfate, water, and additives is 1:30:200:7. After the prepared reaction slurry is added to the reactor, the sealing cap 3 is sealed, and nitrogen gas is introduced through the gas inlet pipe 1 to replace the air in the reactor. Then, benzene is introduced through the benzene inlet pipe 2, with an average benzene flow rate of 54.2 kg / h and a slurry circulation rate of 151.4 kg / h. The stirring device 4 is turned on and the speed is set to 300 r / min. The reactor is heated to 140°C through the insulation jacket 5. After the temperature stabilizes, hydrogen gas is introduced through the gas inlet pipe 1, and the flow rate is controlled to maintain a stable pressure of 5.0 MPa.

[0090] In this embodiment, a distinct stratification is formed in the upper settling zone. After the reaction, the product flows out from product outlet 8 and is measured. When the benzene conversion rate is 53.6%, the cyclohexene selectivity is 79.4%.

[0091] Example 6

[0092] In this embodiment, an equal mass mixture of diethylamine and diethanolamine (mass ratio of 2:5) was used instead of the additive mixture in Example 5, and other conditions and reaction parameters were set in the same way as in Example 5.

[0093] In this embodiment, a distinct stratification is formed in the upper settling zone, and the cyclohexene selectivity is 78.6% when the benzene conversion rate is 52.3%.

[0094] By comparing Examples 1-2 and Comparative Example 1, as well as Example 3 and Comparative Example 2, it can be concluded that the reactor of the present invention can achieve higher cyclohexene selectivity compared to a reactor without a deceleration plate. Not wanting to be limited by theory, it is believed that, compared to conventional reactors, the reactor of the present invention further improves the separation efficiency of oil-phase products and aqueous slurry, reduces backmixing, and inhibits the deep hydrogenation reaction of cyclohexene with the catalyst in the aqueous slurry to generate cyclohexane, thus resulting in higher cyclohexene selectivity.

[0095] Furthermore, by comparing Examples 1 and 2, and Examples 1 and 4, it can be found that the pore size, porosity, and pore distribution of the deceleration plate affect the selectivity of the cyclohexene product. By comparing Example 3 and Comparative Example 3, it can be concluded that changing the parameters of the deceleration plate will achieve different deceleration effects, thereby affecting the formation of the oil-water separation interface. Examples 5 and 6 show that the addition of organic additives in the test method has a good effect.

[0096] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A benzene selective hydrogenation reactor characterized by, The reactor comprises a reaction kettle, a feeding pipeline, a stirring device (4), a heat preservation jacket (5), a deceleration plate (6), a slurry backflow pipeline (7), a product outlet (8) and an exhaust pipeline (9), wherein, The deceleration plate (6) is arranged in the reaction kettle and divides the reaction kettle into a lower reaction zone and an upper settling zone, the deceleration plate (6) is provided with a deceleration channel, the lower reaction zone and the upper settling zone are communicated through the deceleration channel, the diameter of the deceleration channel in the deceleration plate (6) is 0.1 cm-10 cm, the aperture of the deceleration channel decreases from bottom to top, the aperture of the deceleration channel on the lower surface is 5-30 times of the aperture on the upper surface; the density of the deceleration channel gradually decreases from the center to the edge, the spacing of the outermost deceleration channel of the deceleration plate is 1.5-10 times of the spacing of the central deceleration channel; One end of the feeding pipeline is located outside the reaction kettle, and the other end extends into the lower reaction zone; The stirring device (4) is provided with a stirring element, and the stirring element is arranged in the lower reaction zone; The heat preservation jacket (5) is arranged outside the reaction kettle and surrounds at least part of the reaction kettle; The slurry backflow pipeline (7) is arranged outside the reaction kettle, one end of which is connected with a liquid outlet of the upper settling zone, and the other end is connected with a liquid return port of the lower reaction zone; The product outlet (8) is arranged in the upper settling zone and is higher than the liquid outlet; The exhaust pipeline (9) is arranged at the upper part of the reaction kettle.

2. The benzene selective hydrogenation reactor of claim 1, wherein: The aperture of the deceleration channel on the lower surface of the deceleration plate is 6-20 times of the aperture on the upper surface; and / or the spacing of the outermost deceleration channel of the deceleration plate is 2-8 times of the spacing of the central deceleration channel; and / or the deceleration plate is installed at 1 / 2-2 / 3 height.

3. The benzene selective hydrogenation reactor of claim 1 or 2, wherein: The aperture of the deceleration channel on the lower surface of the deceleration plate is 8-15 times of the aperture on the upper surface; and / or the spacing of the outermost deceleration channel of the deceleration plate is 3-6 times of the spacing of the central deceleration channel.

4. The benzene selective hydrogenation reactor of claim 3, wherein: The feeding pipeline comprises a gas feeding pipeline (1) and a benzene feeding pipeline (2).

5. The benzene selective hydrogenation reactor of claim 4, wherein: One end of the gas feeding pipeline (1) and the benzene feeding pipeline (2) extends into the bottom of the lower reaction zone and opens downward or towards the stirring element; and / or, a flow meter and a flow regulating valve are respectively arranged on the gas feeding pipeline (1) and the benzene feeding pipeline (2).

6. The benzene selective hydrogenation reactor of claim 1 or 2, wherein: The deceleration plate (6) comprises a plurality of deceleration plate elements, a plurality of through holes are arranged on each deceleration plate element, and the through holes of the plurality of deceleration plate elements are communicated to form the deceleration channel; And / or, the material of the deceleration plate (6) is stainless steel mesh, porous ceramic material or film; And / or, a plurality of limiting screw sets for installing the deceleration plate (6) are arranged on the inner wall of the reaction kettle in the vertical direction, so as to install the deceleration plate (6) at different heights.

7. The benzene selective hydrogenation reactor of claim 1 or 2, wherein: The slurry backflow pipeline (7) comprises a main backflow pipeline and an auxiliary backflow pipeline arranged in parallel, and a pump and an on-off valve are arranged on the auxiliary backflow pipeline; And / or, the stirring element is arranged on the lower side of the lower reaction zone and is horizontally aligned with the liquid return port; And / or, a pressure gauge and a pressure regulating valve are arranged on the exhaust pipe (9). And / or, a heat exchange medium is circulated in the heat preservation jacket (5).

8. A process for the selective hydrogenation of benzene, characterized in that: The method is performed by the selective hydrogenation reactor of benzene according to any one of claims 1-7.

9. The method of selective hydrogenation of benzene according to claim 8, wherein: Specifically comprising the following steps: 1) preparing a reaction slurry comprising a catalyst, water and zinc sulfate and adding it into the selective hydrogenation reactor of benzene; 2) replacing air in the selective hydrogenation reactor of benzene with an inert gas such as nitrogen and adding benzene; 3) heating the selective hydrogenation reactor of benzene to 100-200℃ and passing hydrogen to perform the reaction; 4) obtaining the target product from the product outlet.

10. The method of selective hydrogenation of benzene according to claim 9, wherein: In step 3), the selective hydrogenation reactor of benzene is heated to 130-160℃; and / or the hydrogen pressure is controlled to be 4-5 MPa.

11. The method of selective hydrogenation of benzene according to claim 9, wherein: The average flow rate of benzene is 30-60 kg / h; and / or the circulation amount of the reaction slurry is 60-160 kg / h.

12. The method of claim 10, wherein: The average flow rate of benzene is 30-40 kg / h; and / or the circulation amount of the reaction slurry is 60-70 kg / h.

13. The process for the selective hydrogenation of benzene according to any one of claims 9-12, characterized in that: The reaction of step 3) is performed at a rotation speed of 200-600 r / min.

14. The method of claim 13, wherein the benzene selective hydrogenation reaction is conducted in the presence of a catalyst comprising palladium and a metal selected from the group consisting of silver, gold, copper, zinc, and combinations thereof. The reaction of step 3) is performed at a rotation speed of 300-500 r / min.

15. The process for the selective hydrogenation of benzene according to any one of claims 9-12, characterized in that: The catalyst is selected from a metal-modified ZrO2 catalyst, a SiO2 catalyst and an Al2O3-based catalyst; and / or the mass ratio of the catalyst, water and zinc sulfate is 1: (50-500): (0-80).

16. The process for the selective hydrogenation of benzene according to any one of claims 9-12, characterized in that: The reaction slurry further comprises an additive selected from one or a combination of 1,3-propanediol, polyethylene glycol, ethylene glycol, ethanolamine, diethanolamine, diphenylamine, ethylenediamine and diethylamine.

17. The method of claim 16, wherein the benzene selective hydrogenation reaction is conducted at a temperature of from about 20°C to about 100°C. The amount of the additive accounts for 0.01%-10% of the mass of water.

18. The method of claim 17, wherein: The amount of the additive accounts for 0.01%-4% of the mass of water.

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