Process and system for benzene hydroalkylation
By controlling the circulating stream and hydrogen flow rate and regulating the temperature in a multi-bed alkylation reactor, the problem of unsatisfactory catalyst performance was solved, catalyst life and energy utilization were improved, and the efficiency of benzene hydrogenation alkylation was enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-06
- Publication Date
- 2026-06-09
AI Technical Summary
The existing catalysts used in the hydrogenation alkylation of benzene have unsatisfactory performance and short service life, produce many byproducts, and have low energy utilization.
In a multi-bed alkylation reactor, benzene hydrogenation alkylation is carried out by precisely controlling the inlet and outlet temperatures of each bed through the control of the circulating stream and hydrogen flow rate, thereby achieving optimal catalyst performance and recovering reaction heat.
It improved catalyst lifespan, reduced production energy consumption, and increased selectivity and product yield for cyclohexylbenzene and hydrogenated terphenyl.
Smart Images
Figure HDA0005175459410000011 
Figure HDA0005175459410000012
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical technology, and more specifically to a method and system for the hydrogenation and alkylation of benzene. Background Technology
[0002] Benzene hydroalkylation technology is characterized by readily available and simple raw materials, low cost, and short process. The hydroalkylation product, cyclohexylbenzene, is an important chemical intermediate that can be oxidized to produce phenol and cyclohexanone. It can also be used as an additive in lithium-ion secondary battery electrolytes, providing overcharge protection. Due to its high cetane number, it can also be used as a cetane number blending component in diesel fuel. Another product, hydrogenated terphenyl, is a major base oil feedstock for L-QD340 and has significant industrial application value. Therefore, benzene hydroalkylation is an ideal choice for producing cyclohexylbenzene and hydrogenated terphenyl. However, benzene hydroalkylation reactions often suffer from unsatisfactory catalyst performance and short lifespan; furthermore, the reaction generates numerous byproducts, resulting in low energy utilization of the entire production system. Summary of the Invention
[0003] To address one of the aforementioned technical problems in the prior art, the present invention provides a method and system for the hydrogenation alkylation of benzene.
[0004] In a first aspect, the present invention provides a method for the hydrogenation alkylation of benzene, the method comprising the following steps:
[0005] The benzene-containing feedstock is alkylated with hydrogen in an alkylation reactor with a multi-bed structure to obtain the reaction products and a circulating stream containing the reaction products.
[0006] The circulating stream containing the reaction products is divided into multiple streams and returned to each bed section to be mixed with hydrogen and subjected to alkylation reaction.
[0007] In this invention, benzene-containing feedstock enters the alkylation reactor from the first bed layer for alkylation reaction, and hydrogen gas enters the alkylation reactor from each of the bed layers for alkylation reaction.
[0008] According to some embodiments of the invention, the alkylation reaction is carried out in an alkylation reactor having an N-stage bed. In some embodiments, N ≥ 2. In some preferred embodiments, 2 ≤ N ≤ 5, for example, N is 2, 3, 4, or 5. In some embodiments, N = 3.
[0009] In some embodiments, the benzene-containing feedstock and hydrogen undergo an alkylation reaction in the first bed of the alkylation reactor to obtain reaction products and N+1 circulating streams containing the reaction products. Of the N+1 circulating streams, one stream is mixed with the benzene-containing feedstock and returned to the first bed; the remaining N streams undergo heat exchange with the benzene-containing feedstock and are then cooled. One stream is then mixed with an optional benzene-containing feedstock and returned to the first bed, and the remaining N-1 streams are returned to the second to Nth bed sections respectively. In some embodiments, the cooling temperature is 40–100°C. In some embodiments, the cooling temperature is 50–90°C. In some embodiments, the cooling temperature is 55–65°C.
[0010] In some embodiments, a benzene-containing feedstock undergoes an alkylation reaction with hydrogen in a first bed to obtain reaction products, a first circulating stream containing the reaction products, and a second circulating stream containing the reaction products. The first circulating stream exchanges heat with the benzene-containing feedstock and is then cooled before being divided into N streams. One stream is mixed with an optional benzene-containing feedstock and returned to the first bed, while the other N-1 streams are returned to the second to Nth bed sections respectively. The second circulating stream is mixed with the heat-exchanged benzene-containing feedstock and then returned to the first bed.
[0011] In some embodiments, the ratio of the flow rate of the second circulating stream to the total flow rate of the first and second circulating streams is (0.01–0.05):1. In some embodiments, the ratio of the flow rate of the reaction product to the total flow rate of the first and second circulating streams is (0.5–1.5):1, preferably (0.6–1.2):1.
[0012] In some embodiments, the reaction products obtained in the (N-1)th bed are introduced into the Nth bed, mixed with hydrogen, and subjected to an alkylation reaction.
[0013] In this invention, the inlet temperature of each bed section is controlled by the flow rate of the circulating material entering each bed section, and the outlet temperature of each bed section is controlled by the flow rate of hydrogen entering each bed section.
[0014] In some embodiments, the flow rate of the circulating material entering each bed section is adjusted so that the temperature difference between the inlet of any two bed sections is not higher than 5°C, preferably not higher than 2°C, more preferably not higher than 1°C, further preferably not higher than 0.5°C, and even more preferably 0°C.
[0015] In some embodiments, the flow rate of hydrogen entering each bed section is adjusted so that the temperature difference between the outlets of any two bed sections is not higher than 5°C, preferably not higher than 2°C, more preferably not higher than 1°C, even more preferably not higher than 0.5°C, and even more preferably 0°C.
[0016] In some embodiments, the ratio of the hydrogen flow rate entering the second bed section to the total hydrogen flow rate entering all bed sections is (0.3 to 0.4):1, for example, 0.3:1, 0.32:1, 0.35:1, 0.38:1, 0.4:1, or any value between them. In some embodiments, the ratio of the hydrogen flow rate entering the Nth bed section to the hydrogen flow rate entering the (N-1)th bed section is (1 to 1.5):1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or any value between them.
[0017] In some embodiments, the ratio of the flow rate of the circulating material entering the first bed layer to the total flow rate of the circulating material is (0.25 to 0.3):1, for example, 0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, 0.3:1 or any value between them.
[0018] In some embodiments, the ratio of the flow rate of the circulating material entering the Nth bed segment to the total flow rate of the circulating material is (0.3 to 0.5):1, for example, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1 or any value between them.
[0019] In some implementations, the ratio of the flow rate of the circulating material entering the Nth bed segment to the flow rate of the circulating material entering the (N-1)th bed segment is (1 to 1.5):1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or any value between them.
[0020] In some embodiments, the ratio of the flow rate of the reaction product to the total flow rate of the circulating stream containing the reaction product is (0.5 to 1.5):1, for example, 0.5:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.5:1 or any value between them, preferably (0.6 to 1.2):1.
[0021] In some embodiments, the inlet temperature of each bed section is independently 140 to 160°C, for example 140°C, 145°C, 150°C, 155°C, 160°C or any value between them, preferably 145 to 155°C.
[0022] In some embodiments, the outlet temperature of each bed section is independently 160 to 200°C, for example 160°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C or any value between them, preferably 175 to 185°C.
[0023] According to some embodiments of the present invention, the pressure of the alkylation reaction is 1.4 MPaG to 2.5 MPaG, for example 1.4 MPaG, 1.5 MPaG, 1.8 MPaG, 2.0 MPaG, 2.2 MPaG, 2.5 MPaG or any value between them, preferably 1.5 to 2.0 MPaG.
[0024] According to some embodiments of the present invention, in step (1), the ratio of the total molar amount of benzene in the benzene-containing raw material to the total molar amount of hydrogen entering each bed section is (2-6):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1 or any value between them, preferably (2-4.5):1, more preferably (2-3):1.
[0025] According to some embodiments of the present invention, the reaction products include cyclohexylbenzene and / or hydrogenated terphenyl. According to some embodiments of the present invention, the reaction products further include one or more of hydrogen, benzene, cyclohexane, and methylcyclopentane. According to some embodiments of the present invention, the reaction products include cyclohexylbenzene, hydrogenated terphenyl, hydrogen, benzene, cyclohexane, and methylcyclopentane.
[0026] According to some embodiments of the present invention, the alkylation reaction is carried out in the presence of a catalyst. In some embodiments, the catalyst preferably comprises a catalyst consisting of a metal active component, an inorganic oxide, and a molecular sieve. In some embodiments, the metal active component comprises one or more of Ru, Pd, Pt, Ni, Co, Mo, and W, for example, one or more of Pt, Pd, Ru, and Ni. In some embodiments, the content of the metal active component in the catalyst is 0.1 wt% to 1.0 wt%. In some embodiments, the molecular sieve comprises one or more of β, Y, MCM-22, PSH-3, SSZ-25, MCM-49, and MCM-56, for example, one or more of β, Y, and MCM-22. In some embodiments, the inorganic oxide comprises one or more of Group IIA, Group IVB, Group IIIA, and Group IVA element oxides; for example, one or more of alumina, silicon oxide, and titanium oxide.
[0027] In a second aspect, the present invention provides a system for the hydrogenation alkylation of benzene, comprising:
[0028] An alkylation reactor having multiple bed sections is used to alkylate a benzene-containing feedstock with hydrogen to obtain reaction products and multiple circulating streams containing reaction products. The multiple circulating streams containing reaction products are respectively transported to each bed section to mix with hydrogen and carry out alkylation reactions.
[0029] According to some embodiments of the present invention, the alkylation reactor is provided with a reaction product outlet and a circulating product outlet, and each bed section is provided with a hydrogen inlet and a liquid phase inlet, wherein the circulating product outlet is connected to the liquid phase inlet of each bed section through multiple ports respectively.
[0030] According to some embodiments of the present invention, the alkylation reactor has N bed sections, and the recycle product outlet is connected to the liquid phase inlet of each bed section through N+1 ports, so as to divide the recycle product into N+1 streams and respectively transport them to the N bed sections, where N≥2. In some embodiments, 2≤N≤5, for example, N is 2, 3, 4 or 5. In some embodiments, N=3.
[0031] According to some embodiments of the present invention, each bed section is further provided with a reaction product outlet. In some embodiments, the reaction product outlet of the (N-1)th bed section is connected to the liquid phase inlet of the Nth bed section, so that the reaction product of the (N-1)th bed section enters the Nth bed section for alkylation reaction.
[0032] According to some embodiments of the present invention, the liquid phase feed port of the first bed is used to allow benzene-containing raw materials and circulating streams to enter the first bed, and the liquid phase feed port of the Nth bed is used to allow the reaction products and circulating streams of the N-1th bed to enter the Nth bed.
[0033] According to some embodiments of the present invention, each section of the alkylation reactor is further equipped with a flow controller at the hydrogen inlet and liquid feed inlet to regulate the inlet and outlet temperatures of each section of the bed.
[0034] According to some embodiments of the present invention, a heat exchanger and / or a cooler are further provided between each port of the circulating product and each liquid phase feed port connected thereto. The heat exchanger is used to exchange heat between the circulating product and the benzene-containing raw material, and the cooler is used to cool the circulating product.
[0035] In some embodiments, the circulating product outlet is connected to the outlet of the heat exchanger through a first port, which is used to mix part of the circulating material with the benzene-containing material after heat exchange and then enter the first bed. The circulating product outlet is connected to the heat exchanger and the cooler in sequence through a second port, and at the outlet of the cooler, it is connected to the liquid phase inlet of the second bed to the Nth bed through N-1 ports respectively.
[0036] According to some embodiments of the present invention, the system further includes a separation device connected to the reaction product outlet of the alkylation reactor for separating the obtained reaction products.
[0037] Thirdly, the present invention provides the application of the above system in the hydrogenation alkylation reaction of benzene.
[0038] In some embodiments, the application includes the use in the hydrogenation of benzene to prepare cyclohexylbenzene and / or hydrogenated terphenyl.
[0039] Compared with the prior art, the present invention has the following beneficial effects:
[0040] This invention involves reacting benzene and hydrogen in a multi-stage fixed-bed reactor to produce cyclohexylbenzene and hydrogenated terphenyl. A portion of the reaction products are recycled as feedstock, exchanging heat with the benzene-containing raw material and then circulating in separate streams to each catalyst bed. By controlling the flow rates of the recycled feedstock and hydrogen in each bed stage, the inlet and outlet temperatures of each bed stage can be precisely controlled. This ensures that the inlet temperature and temperature rise of each bed stage are identical, maximizing the catalyst's catalytic performance, increasing its lifespan, and simultaneously recovering the reaction heat, thus reducing production energy consumption. Attached Figure Description
[0041] Figure 1 This is a process flow diagram for the preparation of cyclohexylbenzene and hydrogenated terphenyl by benzene hydrogenation alkylation reaction according to a specific embodiment of the present invention; wherein, R1 is an alkylation reactor with three beds, E1 is a circulating product heat exchanger, E2 is a circulating product cooler, 1 is total hydrogen, 2 is hydrogen entering the second bed, 3 is hydrogen entering the third bed, 4 is the reaction product, 5 is the circulating product, 6 is a portion of the circulating product entering the first bed, 7 is another portion of the circulating product entering the first bed, 9 is the circulating product entering the third bed, 10 is the circulating product entering the second bed, 8 is benzene-containing feedstock, and 11 is the liquid phase feedstock of the first bed.
[0042] Figure 2 The process flow diagram for the preparation of cyclohexylbenzene and hydrogenated terphenyl by the hydrogenation alkylation reaction of benzene in the comparative example is shown. In the diagram, R1 is an alkylation reactor with three beds, 1 is total hydrogen, 2 is hydrogen entering the second bed, 3 is hydrogen entering the third bed, 4 is the reaction product, and 5 is benzene-containing feedstock. Detailed Implementation
[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.
[0044] Unless otherwise specified, all reagents used in the following experiments of this invention are commercially available products or reagents prepared according to conventional methods. Unless otherwise specified, all methods used in the experiments are conventional experimental methods. Unless otherwise specified, all instruments used in the experiments are commercially available.
[0045] Figure 1 A process flow diagram for preparing cyclohexylbenzene and hydrogenated terphenyl by benzene hydrogenation alkylation reaction according to a specific embodiment of the present invention is shown. The method includes the following steps:
[0046] The benzene-containing feedstock 8 is subjected to a hydrogenation alkylation reaction with hydrogen in an alkylation reactor R1 with a three-bed structure to obtain reaction product 4 and recycled product 5.
[0047] The recycled product 5 is divided into two streams. One stream (recycled product 6) is mixed with the benzene-containing raw material 8 at the cold end outlet of the recycled product heat exchanger E1 and then enters the first bed. The other stream enters the recycled product heat exchanger E1 and exchanges heat with the benzene-containing raw material 8 before entering the recycled product cooler E2 for cooling. After cooling, the recycled product is divided into three streams (recycled product 7, recycled product 9, and recycled product 10) at the outlet of E2. One stream (recycled product 7) is mixed with the benzene-containing raw material 8 and then enters the first bed through E1. The other two streams (recycled product 9 and recycled product 10) enter the second and third bed sections, respectively.
[0048] Furthermore, each bed section is loaded with a catalyst, the composition of which includes, for example, metallic Pt, MCM-22 molecular sieve and alumina, wherein the Pt content is 0.5 wt%.
[0049] Furthermore, the outlet of the recycled product 5 is connected to the liquid phase feed port of the first bed of the alkylation reactor through the recycled product heat exchanger E1; the outlet of the recycled product 5 is also connected to the liquid phase feed ports of the second bed and the third bed through the recycled product heat exchanger E1 and the recycled product cooler E2.
[0050] Furthermore, each bed section has a hydrogen inlet and a liquid phase inlet. The liquid phase inlet of the first bed section consists of raw materials containing benzene and some recycled products (recycled product 6 and recycled product 7). The liquid phase inlet of the second bed section consists of some recycled products (recycled product 10) and the reaction products of the first bed section. The liquid phase inlet of the third bed section consists of some recycled products (recycled product 9) and the reaction products of the second bed section.
[0051] Furthermore, the flow rates of hydrogen feed and liquid feed in each bed section are controlled. By controlling the flow rate of hydrogen in each bed section, the outlet temperature of each bed section is made the same. By controlling the flow rate of the circulating products of the liquid feed in each bed section, the inlet temperature of each bed section is made the same.
[0052] Furthermore, the reaction products contain hydrogen, benzene, cyclohexane, methylcyclopentane, cyclohexylbenzene, and hydrogenated terphenyl.
[0053] Furthermore, the reaction product 4 is fed into a subsequent separation system to obtain cyclohexylbenzene and hydrogenated terphenyl.
[0054] Example 1
[0055] A system for producing cyclohexylbenzene and hydrogenated terphenyl by benzene hydrogenation alkylation with a capacity of 10,000 tons / year adopts... Figure 1 The process flow shown and the specific implementation method described above, the catalyst is composed of metal Pt, MCM-22 molecular sieve and alumina, wherein the Pt content is 0.5wt%, and the main process operating parameters of the system during stable operation are listed in Table 1.
[0056] Table 1
[0057] project parameter Number of segments 3 Molar ratio of benzene to total hydrogen in Logistics 8 2.5 Inlet temperature for each segment, ℃ 150 The outlet temperature of each section, in °C 175 Reaction pressure, MPaG 1.8 E2 cooling temperature, °C 85 Hydrogen conversion rate, % 99.9 Cyclohexylbenzene selectivity, % 75 Selectivity of hydrogenated terphenyl, % 15 Flow ratio of Logistics 2 to Logistics 1 0.32 Logistics 3 to Logistics 1 flow ratio 0.42 Logistics 6 to Logistics 5 Flow Ratio 0.02 Logistics 7 to Logistics 5 flow ratio 0.25 Logistics 4 vs. Logistics 5 Flow Ratio 0.67 Logistics 9 to Logistics 5 flow ratio 0.42 Circulating water usage, tons / ton (cyclohexylbenzene + hydrogenated terphenyl) 13 First stage catalyst life, month 23 Second stage catalyst life, month 24 The third stage catalyst lifespan, month 25
[0058] Example 2
[0059] A system for producing cyclohexylbenzene and hydrogenated terphenyl by benzene hydrogenation alkylation with a capacity of 10,000 tons / year adopts... Figure 1 The system and process flow shown above, as well as the specific implementation method described above, are illustrated. The catalyst consists of metallic Pt, MCM-22 molecular sieve, and alumina, with a Pt content of 0.5 wt%. The main process operating parameters for stable operation of the system are listed in Table 2.
[0060] Unlike Example 1, the molar ratio of benzene to hydrogen was increased from 2.5 to 4, and the temperature rise per stage was reduced to 10°C. At this time, the selectivity of cyclohexylbenzene and hydrogenated terphenyl increased. However, due to the increase in the molar ratio of benzene to hydrogen, the benzene feed in the first stage increased, and the catalyst was affected by impurities, resulting in a slight decrease in the catalyst life of the first stage.
[0061] Table 2
[0062] project parameter Number of segments 3 Molar ratio of benzene to total hydrogen in Logistics 8 4 Inlet temperature for each segment, ℃ 150 The outlet temperature of each section, in °C 160 Reaction pressure, MPaG 1.8 E2 cooling temperature, °C 85 Hydrogen conversion rate, % 99.9 Cyclohexylbenzene selectivity, % 78 Selectivity of hydrogenated terphenyl, % 16 Flow ratio of Logistics 2 to Logistics 1 0.33 Logistics 3 to Logistics 1 flow ratio 0.41 Logistics 6 to Logistics 5 Flow Ratio 0.02 Logistics 7 to Logistics 5 flow ratio 0.25 Logistics 4 vs. Logistics 5 Flow Ratio 1.05 Logistics 9 to Logistics 5 flow ratio 0.41 Circulating water usage, tons / ton (cyclohexylbenzene + hydrogenated terphenyl) 1 First stage catalyst life, month 21 Second stage catalyst life, month 24 The third stage catalyst lifespan, month 25
[0063] Comparative Example 1
[0064] A system for producing cyclohexylbenzene and hydrogenated terphenyl by benzene hydrogenation alkylation with a capacity of 10,000 tons / year adopts... Figure 2 The process flow shown involves a hydrogenation alkylation reaction of benzene-containing feedstock 5 and hydrogen in an alkylation reactor R1 with three beds to obtain reaction product 4. Benzene-containing feedstock 5 enters the first bed and reacts with the hydrogen entering the first bed. Each bed has a hydrogen inlet and a catalyst composed of metal Pt, MCM-22 molecular sieve, and alumina, with a Pt content of 0.5 wt%. The molar ratio of benzene to total hydrogen in feedstock 5 is 4. Hydrogen is fed in equal amounts in each bed. The main process operating parameters for stable operation of this system are listed in Table 3.
[0065] Table 3
[0066] project parameter Number of segments 3 Molar ratio of benzene to total hydrogen in logistics 5 4 First inlet temperature, ℃ 150 First-stage outlet temperature, ℃ 180 Second inlet temperature, ℃ 179 Second-stage outlet temperature, ℃ 210 The inlet temperature of the third section, ℃ 209 Fourth stage inlet temperature, ℃ 240 Reaction pressure, MPaG 1.8 Hydrogen conversion rate, % 99.9 Cyclohexylbenzene selectivity, % 70 Selectivity of hydrogenated terphenyl, % 10 First stage catalyst life, month 18 Second stage catalyst life, month 16 The third stage catalyst lifespan, month 14
[0067] As shown in Table 3, after the external circulation was removed, the inlet temperature and temperature rise of each catalyst bed could not be the same under the total benzene / hydrogen molar ratio, resulting in a temperature rise of 90°C for the entire bed. This seriously affected the selectivity of cyclohexylbenzene and hydrogenated terphenyl. Furthermore, due to the increase in temperature rise, the catalyst was severely carbonized, and its lifespan was greatly reduced.
[0068] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. A method for the hydrogenation and alkylation of benzene, comprising the following steps: The benzene-containing feedstock is alkylated with hydrogen in an alkylation reactor with a multi-bed structure to obtain the reaction products and a circulating stream containing the reaction products. The circulating stream containing the reaction products is divided into multiple streams and returned to each bed section to be mixed with hydrogen and subjected to alkylation reaction.
2. The method according to claim 1, characterized in that, The alkylation reaction is carried out in an alkylation reactor with an N-stage bed, where N ≥ 2; preferably 2 ≤ N ≤ 5, more preferably N = 3; Preferably, the benzene-containing feedstock and hydrogen undergo an alkylation reaction in the first bed to obtain reaction products, a first circulating stream containing the reaction products, and a second circulating stream containing the reaction products. The first circulating stream, after heat exchange with the benzene-containing feedstock and cooling, is divided into N streams. One stream is mixed with an optional benzene-containing feedstock and returned to the first bed, while the other N-1 streams are returned to the second to Nth bed sections respectively. The second circulating stream, after heat exchange with the benzene-containing feedstock, is returned to the first bed. Preferably, the reaction product obtained in the (N-1)th bed section enters the Nth bed section, mixes with hydrogen, and undergoes an alkylation reaction.
3. The method according to claim 1 or 2, characterized in that, The flow rate of the circulating stream entering each bed section is adjusted so that the inlet temperature difference between any two bed sections is not higher than 5°C, preferably not higher than 2°C, and more preferably 0°C; and / or, the flow rate of hydrogen entering each bed section is adjusted so that the outlet temperature difference between any two bed sections is not higher than 5°C, preferably not higher than 2°C, and more preferably 0°C. Preferably, the ratio of the hydrogen flow rate entering the second bed to the total hydrogen flow rate entering each bed is (0.3-0.4):1, and the ratio of the hydrogen flow rate entering the Nth bed to the hydrogen flow rate entering the (N-1)th bed is (1-1.5):
1. Preferably, the ratio of the flow rate of the circulating material entering the first bed layer to the total flow rate of the circulating material is (0.25~0.3):1; Preferably, the ratio of the flow rate of the circulating material entering the Nth bed layer to the total flow rate of the circulating material is (0.3~0.5):1; Preferably, the ratio of the flow rate of the circulating material entering the Nth bed layer to the flow rate of the circulating material entering the (N-1)th bed layer is (1~1.5):1; Preferably, the ratio of the flow rate of the reaction product to the total flow rate of the circulating stream containing the reaction product is (0.5-1.5):1, more preferably (0.6-1.2):
1.
4. The method according to any one of claims 1-3, characterized in that, The inlet temperature of each bed section is independently 140–160°C, preferably 145–155°C; the outlet temperature of each bed section is independently 160–200°C, preferably 175–185°C; and / or, The alkylation reaction is carried out at a pressure of 1.4 MPaG to 2.5 MPaG, preferably 1.5 to 2.0 MPaG; and / or, The cooling temperature is 40–100°C, preferably 50–90°C, and more preferably 55–65°C.
5. The method according to any one of claims 1-4, characterized in that, The ratio of the total molar amount of benzene in the benzene-containing feedstock to the total molar amount of hydrogen entering each bed section is (2-6):1, preferably (2-4.5):1, more preferably (2-3):1; and / or, The reaction products include cyclohexylbenzene and / or hydrogenated terphenyl. Optionally, the reaction products also include one or more of hydrogen, benzene, cyclohexane, and methylcyclopentane.
6. The method according to any one of claims 1-5, characterized in that, The alkylation reaction is carried out in the presence of a catalyst, preferably comprising a catalyst composed of a metal active component, an inorganic oxide, and a molecular sieve. Preferably, the metal active component includes one or more of Ru, Pd, Pt, Ni, Co, Mo, and W, and more preferably includes one or more of Pt, Pd, Ru, and Ni; Preferably, the content of the metal active component in the catalyst is 0.1 wt% to 1.0 wt%. Preferably, the molecular sieve includes one or more of β, Y, MCM-22, PSH-3, SSZ-25, MCM-49, and MCM-56, and more preferably one or more of β, Y, and MCM-22; Preferably, the inorganic oxide includes one or more of Group IIA element oxides, Group IVB element oxides, Group IIIA element oxides, and Group IVA element oxides, and more preferably includes one or more of aluminum oxide, silicon oxide, and titanium oxide.
7. A system for the hydrogenation and alkylation of benzene, comprising: An alkylation reactor having multiple bed sections is used to alkylate a benzene-containing feedstock with hydrogen to obtain reaction products and multiple circulating streams containing reaction products. The multiple circulating streams containing reaction products are respectively transported to each bed section to mix with hydrogen and carry out alkylation reactions.
8. The system according to claim 7, characterized in that, The alkylation reactor is provided with a reaction product outlet and a recycled product outlet, and each bed section is provided with a hydrogen inlet and a liquid phase inlet. The recycled product outlet is connected to the liquid phase inlet of each bed section through multiple ports. Preferably, the alkylation reactor has N bed sections, and the recycle product outlet is connected to the liquid phase inlet of each bed section through N+1 ports, so as to divide the recycle product into N+1 streams and transport them to the N bed sections respectively, where N≥2; preferably, 2≤N≤5, more preferably, N=3; Preferably, each bed section is also provided with a reaction product outlet. Preferably, the reaction product outlet of the N-1th bed section is connected to the liquid phase inlet of the Nth bed section, so that the reaction product of the N-1th bed section enters the Nth bed section for alkylation reaction. Preferably, the liquid phase feed inlet of the first bed is used to allow benzene-containing raw materials and circulating streams to enter the first bed, and the liquid phase feed inlet of the Nth bed is used to allow the reaction products and circulating streams of the (N-1)th bed to enter the Nth bed.
9. The system according to claim 7 or 8, characterized in that, The hydrogen inlet and liquid feed inlet of each bed section of the alkylation reactor are also equipped with flow controllers to regulate the inlet and outlet temperatures of each bed section; and / or, A heat exchanger and / or cooler are provided between each port of the circulating product and each liquid phase inlet connected thereto. The heat exchanger is used to exchange heat between the circulating product and the benzene-containing raw material, and the cooler is used to cool the circulating product. Preferably, the circulating product outlet is connected to the outlet of the heat exchanger through a first port, so that a portion of the circulating material is mixed with the benzene-containing material after heat exchange and then enters the first bed. The circulating product outlet is connected to the heat exchanger and the cooler in sequence through a second port, and at the outlet of the cooler, it is connected to the liquid phase inlet of the second bed to the Nth bed through N-1 ports respectively.
10. The use of the system according to any one of claims 7-9 in the hydrogenation alkylation reaction of benzene, preferably in the hydrogenation of benzene to prepare cyclohexylbenzene and / or hydrogenated terphenyl.