A catalyst for the alkylation of benzene with cyclohexene to cyclohexylbenzene and its preparation and use

Abstract

The application discloses a catalyst for benzene and cyclohexene alkylation to prepare cyclohexylbenzene and a preparation method and application thereof. The catalyst comprises an ultrathin layered MWW molecular sieve and a heteropoly acid, the layered thickness of the ultrathin layered MWW molecular sieve is 5-10 nm, and the heteropoly acid is one or more of phosphotungstic acid, silicotungstic acid and phosphomolybdic acid. The catalyst can improve the selectivity and service life, and the benzene and cyclohexene alkylation reaction can be carried out at a lower reaction temperature, so that the selectivity of a key by-product, methylcyclopentylbenzene, is reduced.

Description

Technical Field

[0001] This invention relates to the field of fine chemical production technology, specifically to a catalyst for the alkylation of benzene and cyclohexene to produce cyclohexylbenzene, and its preparation and application. Background Technology

[0002] Cyclohexylbenzene (CHB) can be used as an additive in lithium-ion secondary battery electrolytes to improve overcharge protection, reduce electrolyte conductivity, and enhance battery safety, thus possessing significant value. CHB is also a raw material for synthesizing thin-film transistors (TFTs), improving their photochemical stability and reducing viscosity. Furthermore, cyclohexylbenzene has a high cetane number and can be used as a cetane number modifier in diesel fuel.

[0003] In the phenol and acetone manufacturing industry, cyclohexylbenzene can be used to prepare phenol and cyclohexanone through oxidation and acid decomposition reactions, replacing the cumene method for phenol production and addressing the issue of acetone overcapacity. The downstream product of the co-product cyclohexanone is caprolactam, an important raw material for manufacturing synthetic fibers, and has high application value.

[0004] Cyclohexylbenzene can be prepared by Friedel-Crafts alkylation of benzene, hydrogenation of biphenyl, or hydrogenation alkylation of benzene. However, the latter two methods have problems such as low yield of the target product, difficulty in catalyst manufacturing, and high cost, which need to be improved. Therefore, Friedel-Crafts alkylation of benzene is currently the most economical preparation method.

[0005] CN1982263A discloses a method for preparing cyclohexylbenzene from benzene and cyclohexanol under the catalysis of liquid acids such as sulfuric acid and AlCl3, with a yield of 90%. However, due to the use of inorganic liquid acids, there are prominent problems such as high energy consumption for product separation, large waste production, equipment corrosion, and intermittent reaction, which are only suitable for small-batch production.

[0006] CN101219922A, CN101811924A, CN109369322A, CN110606796A, and other publications disclose a series of methods for preparing cyclohexylbenzene using acidic ionic liquids as catalysts. These methods can achieve the effect of inorganic liquid acid catalysis and have the advantage of multiple catalyst recycling. However, the preparation of ionic liquids requires anhydrous and oxygen-free conditions, resulting in high preparation costs. Currently, these methods remain in the laboratory research and development stage.

[0007] The process of catalyzing the alkylation of benzene and cyclohexene to prepare cyclohexylbenzene under liquid-solid conditions using molecular sieve solid acids as catalysts has advantages such as low product separation difficulty and continuous production capability, and has long been regarded as a potential alternative to liquid acid catalysis. CN108435234A discloses a method for applying a molecular sieve-supported heteropolyacid catalyst in the synthesis of cyclohexylbenzene. Using an ultrastable USY-type molecular sieve as a support, heteropolyacids such as phosphotungstic acid are loaded to prepare a catalyst for catalyzing the alkylation of benzene and cyclohexene in a batch high-pressure reactor at a reaction temperature of 100–200℃, achieving a conversion rate of 99% and a cyclohexylbenzene selectivity of 94%. However, the reaction time is 2–8 hours, and it is a batch reaction with low efficiency, making it unsuitable for large-scale continuous production, reflecting the low catalytic efficiency of the catalyst.

[0008] Because the alkylation products of benzene and cyclohexene have relatively large molecular sizes, molecular sieves are prone to pore blockage and deactivation when used as catalysts. While increasing the reaction temperature can promote the diffusion of these molecules, it also leads to an increase in side reactions and improved selectivity for key impurities such as methylcyclopentylbenzene. Furthermore, the boiling point of methylcyclopentylbenzene is close to that of cyclohexylbenzene, making distillation separation difficult. Therefore, developing a catalytic reaction system that simultaneously possesses high selectivity and a long catalyst lifetime is quite challenging. Summary of the Invention

[0009] To address the prominent problems in existing technologies regarding the alkylation of benzene with cyclohexene to produce cyclohexylbenzene, such as low product selectivity, high content of the byproduct methylcyclopentylbenzene, and short catalyst lifetime, this invention provides a catalyst for the alkylation of benzene with cyclohexene to produce cyclohexylbenzene, as well as its preparation and application. Using the catalyst of this invention improves its selectivity and lifetime, allowing the alkylation reaction of benzene with cyclohexene to proceed at a lower reaction temperature, thereby reducing the selectivity of the key byproduct impurity methylcyclopentylbenzene.

[0010] The first aspect of the present invention provides a catalyst for the alkylation of benzene with cyclohexene to produce cyclohexylbenzene, the catalyst comprising an ultrathin layered MWW molecular sieve and a heteropoly acid, wherein the layer thickness of the ultrathin layered MWW molecular sieve is 5-10 nm; the heteropoly acid is one or more of phosphotungstic acid (HPW), silicotungstic acid (HSiW), and phosphomolybdic acid (HPMo), preferably phosphotungstic acid.

[0011] Furthermore, the SiO2 / Al2O3 molar ratio of the ultrathin layered MWW molecular sieve is 10 to 100, preferably 20 to 40.

[0012] Furthermore, in the catalyst, based on the total weight of MWW molecular sieve and binder as oxides, the heteropoly acid content is 10wt% to 100wt% based on anhydrous heteropoly acid molecules, preferably 40wt% to 80wt%.

[0013] Furthermore, the catalyst also includes a binder, which is one or more of alumina or silicon dioxide.

[0014] Furthermore, in the catalyst, the content of binder, calculated as oxide, is 3% to 15% based on the weight of the catalyst, preferably 5% to 10%.

[0015] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps:

[0016] (1) Mix silicon source, aluminum source, alkali source, water, first template agent (T1) and second template agent (T2), crystallize, and obtain ultrathin layered MWW molecular sieve;

[0017] (2) The ultrathin layered MWW molecular sieve obtained in step (1) is subjected to acid exchange, molding, and calcination to obtain the catalyst intermediate;

[0018] (3) The catalyst intermediate obtained in step (2) is impregnated with a heteropoly acid aqueous solution in the presence of a surfactant and then calcined to obtain the catalyst.

[0019] Further, in step (1), the alkali source, water, first template agent (T1) and second template agent (T2) are mixed first, then the silicon source is added and stirred, and finally the aluminum source is added. After aging at 0-40°C for 1-12 hours, the mixture is crystallized.

[0020] Further, in step (1), the silicon source is selected from at least one of silicon dioxide, silica sol, fumed silica, water glass, sodium silicate or tetraethyl silicate, preferably silicon dioxide.

[0021] Further, in step (1), the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, aluminum isopropoxide, aluminum sol, or aluminum hydroxide, preferably aluminum nitrate.

[0022] Further, in step (1), the alkali source is selected from at least one of sodium hydroxide or potassium hydroxide, preferably sodium hydroxide.

[0023] Further, in step (1), the first template agent (T1) is selected from at least one of hexamethyleneimine (HMI), tetrahydropyrrole, hexahydropyridine (PI), 2-methylhexahydropyridine or heptamethylimine, preferably at least one of hexamethyleneimine (HMI) and hexahydropyridine (PI).

[0024] Further, in step (1), the second template agent (T2) is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, dialcyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride or octadecyltrimethylammonium bromide, preferably at least one of hexadecyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium chloride (DTAC).

[0025] Further, in step (1), the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali as OH. - The molar ratio of SiO2 / Al2O3 is calculated to be 10–100, preferably 20–40; OH - The ratio of H2O / SiO2 is 0 to 0.40, preferably 0.05 to 0.15; the ratio of H2O / SiO2 is 10 to 50, preferably 20 to 30; the ratio of T1 / SiO2 is 0.05 to 1.0, preferably 0.1 to 0.5; and the ratio of T2 / SiO2 is 0.001 to 0.1, preferably 0.01 to 0.04.

[0026] Further, in step (1), the crystallization is dynamic crystallization, with a stirring rate of 10-200 rpm, preferably 20-100 rpm; a crystallization temperature of 100-200℃, preferably 150-180℃; and a crystallization time of 24-144h, preferably 48-96h.

[0027] Furthermore, in step (1), after crystallization, the product is washed and dried for later use. Washing and drying are standard operations in the field.

[0028] Further, in step (1), the SiO2 / Al2O3 molar ratio of the ultrathin layered MWW molecular sieve is 10 to 100, preferably 20 to 40.

[0029] Further, in step (2), the acid exchange conditions include: a temperature of 20–100℃, preferably 65–95℃; a time of 0.5–24 h / time, preferably 3–8 h / time; an acid concentration of 0.001–2 mol / L, preferably 0.01–0.5 mol / L; and 1–6 acid exchange cycles, preferably 2–4 times. The mass ratio of the acid solution to the molecular sieve is 2–20, preferably 5–10.

[0030] Further, in step (2), the acid is an organic acid and / or an inorganic acid; preferably, the acid is at least one of oxalic acid, citric acid, formic acid, acetic acid, propionic acid, sulfuric acid, nitric acid and hydrochloric acid.

[0031] Furthermore, in step (2), after acid exchange, the product is washed and dried for later use. Washing and drying are standard operations in the field.

[0032] Further, in step (2), the binder used in the molding process is at least one of boehmite, silica sol, γ-alumina, aluminum hydroxide, or silica, preferably boehmite or silica sol. The binder, calculated as an oxide, has a weight content of 3% to 15% in the catalyst, preferably 5% to 10%.

[0033] Further, in step (2), the calcination temperature is 350-650℃, preferably 500-600℃, and the calcination time is 1-10h, preferably 2-8h.

[0034] Further, in step (3), the above-mentioned catalyst intermediate, namely the shaped ultrathin MWW-type molecular sieve, is impregnated in a heteropoly acid aqueous solution in the presence of a surfactant, and then drained, dried, and calcined to obtain the catalyst. The impregnation is an equal-volume impregnation. The calcination conditions are: a temperature of 350–550°C, preferably 400–500°C, and a time of 1–12 h, preferably 3–6 h.

[0035] Further, in step (3), the surfactant is at least one of a nonionic surfactant or anionic surfactant. The nonionic surfactant is poly(ethylene glycol). x -Propylene glycol y - Ethylene glycol z The triblock oligomer has a molecular weight range of 1100–14600, preferably 4400–8000. The anionic surfactant is one or more of hexadecylbenzenesulfonic acid, hexadecyltrimethyl-p-toluenesulfonic acid, and dodecylbenzenesulfonic acid. The mass ratio of the surfactant to the MWW-type molecular sieve is 0.001–0.10, preferably 0.01–0.05.

[0036] Further, in step (3), the heteropolyacid is one or more of phosphotungstic acid (HPW), silicotungstic acid (HSiW), and phosphomolybdic acid (HPMo), preferably phosphotungstic acid. The mass concentration of the heteropolyacid aqueous solution is 8.3% to 83.3%, preferably 33.3% to 66.7%. During catalyst preparation, the amount of heteropolyacid used is such that, based on the total weight of MWW molecular sieve and binder (calculated as oxides), the loading of heteropolyacid in the final catalyst is 10 to 100 wt%, preferably 40 to 80 wt%.

[0037] A third aspect of the present invention provides a method for preparing cyclohexylbenzene by alkylation of benzene with cyclohexene, comprising an alkylation reaction of benzene with cyclohexene on the above-mentioned catalyst.

[0038] Furthermore, the method employs a fixed-bed reactor.

[0039] Furthermore, in the method for alkylating benzene with cyclohexene to produce cyclohexylbenzene, the molar ratio of benzene to cyclohexene is 3-30, preferably 5-15; the water content in the raw material is <100 mg / kg, preferably <50 mg / kg; the total nitrogen content is <0.1 mg / kg, preferably <0.05 mg / kg; and the total sulfur content is <0.1 mg / kg, preferably <0.05 mg / kg.

[0040] Furthermore, in the method for producing cyclohexylbenzene by alkylation of benzene and cyclohexene, the raw materials benzene and cyclohexene may be selectively pretreated by dehydration and removal of alkalis, depending on the impurity content. The pretreatment may be carried out by adsorption, for example, using 13X molecular sieve as the adsorbent.

[0041] Furthermore, in the method for alkylating benzene with cyclohexene to produce cyclohexylbenzene, the total mass hourly space velocity (WHSV) of the raw materials benzene and cyclohexene is 0.1–6.0 h⁻¹. -1 Preferably, it is 1.0 to 4.0 h. -1 .

[0042] Furthermore, the pressure of the alkylation reaction is 1.0 to 4.0 MPa, preferably 1.5 to 2.5 MPa.

[0043] Furthermore, the alkylation reaction temperature is 80–200°C, preferably 110–150°C.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The present invention uses heteropoly acid supported on ultrathin layered MWW molecular sieve as catalyst. The ultrathin layered MWW molecular sieve is synthesized by a dual template method. Its excellent diffusion performance and high acid content are used to improve its selectivity and service life, so that the alkylation reaction of benzene and cyclohexene can be carried out at a lower reaction temperature, thereby reducing the selectivity of the key by-product impurity methylcyclopentylbenzene.

[0046] (2) The ultrathin layered MWW molecular sieve supported heteropolyacid catalyst provided by the present invention has better alkylation activity and selectivity. Benzene and cyclohexene can be reacted at a lower temperature (preferably 110-150°C). Cyclohexene does not need to be fed in stages to achieve good selectivity. The selectivity of the key byproduct methylcyclopentanebenzene is significantly reduced to below 1.5%, which can greatly reduce separation energy consumption and improve the purity of the product cyclohexylbenzene.

[0047] (3) Under the reaction process conditions used in this invention, the catalyst has a long service life, with a single-pass life of more than 1500 hours, which can meet the requirements of industrial applications. Attached Figure Description

[0048] Figure 1Example 1: XRD pattern of catalyst M1 synthesized;

[0049] Figure 2 SEM image of catalyst M1 synthesized in Example 1. Detailed Implementation

[0050] The present invention will be further illustrated below through examples.

[0051] In this invention, the loading of heteropolyacids in the catalyst active component is determined by X-ray fluorescence spectroscopy (XRF).

[0052] In this invention, the XRD patterns of the catalyst were characterized by phase analysis using a Bruker D8 Advanced X-ray diffractometer with a scanning range of 3–50°, a step size of 0.05°, and a scanning speed of 4° / min.

[0053] In this invention, the SEM images of the catalyst were observed using a FEI Nova NanoSEM 450 electron microscope.

[0054] In this invention, the product after the alkylation reaction of benzene and cyclohexene is analyzed by gas chromatography-FID, and key indicators such as cyclohexene conversion, cyclohexylbenzene selectivity, cyclohexylation selectivity, and methylcyclopentanebenzene selectivity are calculated according to the following formulas:

[0055] Cyclohexene conversion rate = (mass percentage of cyclohexene before reaction - mass percentage of cyclohexene after reaction) / (mass percentage of cyclohexene before reaction) × 100%;

[0056] Cyclohexylbenzene selectivity = (mass percentage of cyclohexylbenzene) / (sum of mass percentages of all products and byproducts) × 100%;

[0057] Cyclohexylation selectivity = (mass percentage of cyclohexylbenzene + dicyclohexylbenzene) / (sum of mass percentages of all products and byproducts) × 100%;

[0058] Selectivity of methylcyclopentylbenzene = (mass percentage of methylcyclopentylbenzene) / (sum of mass percentages of all products and byproducts) × 100%.

[0059]

Example 1

[0060] (1) Add 3.6g NaOH, 11.88g hexamethyleneimine (HMI), and 1.64g cetyltrimethylammonium bromide (CTAB) to 139.1g water. After thorough dissolution and mixing, add 18.00g silica powder and stir vigorously. Then add 7.50g aluminum nitrate nonahydrate and age at room temperature (25℃) for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0061] (2) The above-mentioned molecular sieve intermediate product (SiO2 / Al2O3 molar ratio of 29.5, thickness of 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525 °C for 5 h.

[0062] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M1 was prepared, in which the phosphotungstic acid loading was 61.2 wt%.

[0063]

Example 2

[0064] Compared with Example 1, the only difference is that in step (3), the above-formed ultrathin MWW molecular sieve is immersed in a 66.7% phosphotungstic acid (HPW) aqueous solution, drained, dried, and calcined at 475°C for 4 hours to prepare alkylation catalyst M2, wherein the HPW loading is 79.6%.

[0065]

Example 3

[0066] Compared with Example 1, the only difference is that in step (3), the above-formed ultrathin MWW molecular sieve is immersed in a 33.3% phosphotungstic acid (HPW) aqueous solution, drained, dried, and calcined at 475°C for 4 hours to prepare alkylation catalyst M3, wherein the HPW loading is 41.0%.

[0067]

Example 4

[0068] (1) Add 4.1g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g cetyltrimethylammonium bromide (CTAB) to 139.8g water. After thorough dissolution and mixing, add 18.0g silica powder and stir vigorously. Then add 9.0g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 155℃, the crystallization time is 84 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 25Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0069] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio determined to be 24.3, thickness 5.0–7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525 °C for 5 h.

[0070] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M4 was prepared, in which the phosphotungstic acid loading was 60.8 wt%.

[0071]

Example 5

[0072] (1) Add 2.5g NaOH, 13.4g hexamethyleneimine (HMI), and 2.18g cetyltrimethylammonium bromide (CTAB) to 121.8g water. After thorough dissolution and mixing, add 18.0g silica powder, stir vigorously, and then add 5.6g aluminum nitrate nonahydrate. Aging at room temperature for 6 hours is performed, followed by crystallization in a high-pressure cryogenic chamber lined with polytetrafluoroethylene. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 40Al2O3:0.06OH- :22H2O:0.45HMI:0.020CTAB.

[0073] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio determined to be 38.9, thickness 5.0–7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525 °C for 5 h.

[0074] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M5 was prepared, in which the phosphotungstic acid loading was 61.0 wt%.

[0075]

Example 6

[0076] (1) Add 3.6g NaOH, 11.88g hexamethyleneimine (HMI), and 2.73g cetyltrimethylammonium bromide (CTAB) to 139.1g water. After thorough dissolution and mixing, add 18.00g silica powder and stir vigorously. Then add 7.50g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 165℃, the crystallization time is 144 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.030CTAB.

[0077] (2) The above-mentioned molecular sieve intermediate product (SiO2 / Al2O3 molar ratio of 29.3, thickness of 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80℃ for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525℃ for 5 h.

[0078] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M6 was prepared, in which the phosphotungstic acid loading was 61.4 wt%.

[0079]

Example 7

[0080] (1) Add 3.6g NaOH, 10.20g hexahydropyridine (PI), and 1.64g cetyltrimethylammonium bromide (CTAB) to 139.1g water. After thorough dissolution and mixing, add 18.00g silica powder and stir vigorously. Then add 7.50g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.4PI:0.015CTAB.

[0081] (2) The above-mentioned molecular sieve intermediate product (SiO2 / Al2O3 molar ratio of 29.7, thickness of 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80℃ for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525℃ for 5 h.

[0082] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M7 was prepared, in which the phosphotungstic acid loading was 60.7 wt%.

[0083]

Example 8

[0084] (1) Add 3.6g NaOH, 11.88g hexamethyleneimine (HMI), and 1.19g dodecyltrimethylammonium chloride (DTAC) to 139.1g water. After thorough dissolution and mixing, add 18.00g silica powder and stir vigorously. Then add 7.50g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015DTAC.

[0085] (2) The above-mentioned molecular sieve intermediate product (SiO2 / Al2O3 molar ratio of 28.9, thickness of 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was then calcined in air at 525 °C for 5 h.

[0086] (3) The above-formed ultrathin MWW molecular sieve is immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M8 was prepared, in which the phosphotungstic acid loading was 61.0 wt%.

[0087]

Example 9

[0088] The only difference from Example 1 is that 0.2 mol / L citric acid was used instead of 0.1 mol / L hydrochloric acid. Alkylation catalyst M9 was prepared, with a phosphotungstic acid loading of 60.8 wt%.

[0089]

Example 10

[0090] The shaped ultrathin MWW-type molecular sieve prepared in step (2) of Example 1 was immersed in a 50.0% phosphotungstic acid (HPW) aqueous solution, and the surfactant poly(ethylene glycol) was added to the aqueous solution. x -Propylene glycol y - Ethylene glycol zA triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.02 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M10 was prepared, in which the phosphotungstic acid loading was 61.3 wt%.

[0091]

Example 11

[0092] Change the type of surfactant used in impregnation

[0093] The shaped ultrathin MWW-type molecular sieve prepared in step (2) of Example 1 was impregnated in a 50.0% phosphotungstic acid (HPW) aqueous solution. The surfactant n-hexadecylbenzenesulfonic acid was added to the aqueous solution, with a surfactant-to-MWW molecular sieve mass ratio of 0.04. After draining, drying, and calcining at 475°C for 4 hours, alkylation catalyst M11 was prepared, wherein the phosphotungstic acid loading was 61.4 wt%.

[0094]

Example 12

[0095] The only difference from Example 1 is that the shaped ultrathin MWW molecular sieve prepared in step (2) of Example 1 is immersed in a 50.0% silicotungstic acid (HSiW) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M12 was prepared, in which the silicotungstic acid loading was 60.5 wt%.

[0096]

Example 13

[0097] The only difference from Example 1 is that the shaped ultrathin MWW molecular sieve prepared in step (2) of Example 1 is immersed in a 50.0% phosphomolybdic acid (HPMo) aqueous solution, and the surfactant poly(ethylene glycol) is added to the aqueous solution. x -Propylene glycol y - Ethylene glycol z A triblock oligomer with a molecular weight of 5800 was prepared by adding a surfactant at a mass ratio of 0.04 to the mass of MWW molecular sieve. After draining, drying, and calcining at 475°C for 4 hours, an alkylation catalyst M13 was prepared, with a phosphomolybdic acid loading of 59.8 wt%.

[0098] Comparative Example 1

[0099] Add 3.6g NaOH, 11.88g hexamethyleneimine (HMI), and 1.64g cetyltrimethylammonium bromide (CTAB) to 139.1g water. After thorough dissolution and mixing, add 18.00g silica powder and stir vigorously. Then add 7.50g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with PTFE for crystallization. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water and dry for later use. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0100] The aforementioned molecular sieve intermediate (SiO2 / Al2O3 molar ratio of 29.5, thickness of 5.0–7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h per exchange, for a total of 4 exchanges. After washing and drying, pseudoboehmite and dilute nitric acid were added to form cylindrical catalyst strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was 10% of the total catalyst weight on a dry basis. The strips were then calcined in air at 525 °C for 5 h to prepare the alkylation catalyst C1.

[0101] Comparative Example 2

[0102] The only difference from Example 1 is that CTAB is not added during the molecular sieve preparation process in step (1).

[0103] Add 3.6g NaOH and 11.88g hexamethyleneimine (HMI) to 139.1g water, dissolve and mix thoroughly, then add 18.00g silica powder, stir vigorously, and then add 7.50g aluminum nitrate nonahydrate. Aging at room temperature for 6 hours is performed, followed by crystallization in a high-pressure cryogenic chamber lined with PTFE. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0CTAB.

[0104] The prepared alkylation catalyst is designated C2, in which the phosphotungstic acid loading is 61.1 wt%.

[0105] Comparative Example 3

[0106] The difference compared to Example 1 is as follows:

[0107] Commercially available USY-type molecular sieve (SiO2 / Al2O3 = 6.1), pseudoboehmite, and dilute nitric acid were mixed and molded to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The mixture was calcined in air at 525 °C for 5 h, then impregnated in a 60.0% phosphotungstic acid (HPW) aqueous solution. After draining, drying, and calcining at 475 °C for 4 h, an alkylation catalyst C3 was prepared, in which the phosphotungstic acid loading was 61.2 wt%.

[0108] Comparative Example 4

[0109] The only difference from Example 1 is that equimolar dipentyldimethylammonium iodide (DPenDMAI) is used instead of hexadecyltrimethylammonium bromide (CTAB).

[0110] Comparative Example 4 prepared an alkylation catalyst C4, wherein the phosphotungstic acid loading was 60.2 wt%.

[0111]

Application Example 1

[0112] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene under the catalysis of the catalyst described above. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkalis using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 10. The water content, total nitrogen content, and total sulfur content of the raw materials were 15 mg / kg, 0.03 mg / kg, and 0.05 mg / kg, respectively. The catalysts prepared in Examples 1-13 and Comparative Examples 1-4 were loaded into fixed-bed reactors at a loading rate of 3.0 g. Under the conditions of a reaction temperature of 130°C and a pressure of 2.0 MPa, the pretreated raw materials were introduced at a flow rate of 6.0 g / h, i.e., a raw material space velocity of 2.0 h⁻¹. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 1.

[0113] Table 1

[0114]

[0115] *Data from a 72-hour reaction time.

[0116] **Reaction time for cyclohexene conversion > 99.8%.

[0117]

Application Example 2

[0118] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene under the catalysis of the catalyst prepared above. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkalis using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 12.5. The water content, total nitrogen content, and total sulfur content of the raw materials were 56 mg / kg, 0.05 mg / kg, and 0.07 mg / kg, respectively. The catalysts prepared in Example 1 and Comparative Example 1 were loaded into fixed-bed reactors at a loading rate of 3.0 g. Under the conditions of a reaction temperature of 145°C and a pressure of 2.5 MPa, the pretreated raw materials prepared above were introduced at a flow rate of 12.0 g / h, i.e., a raw material space velocity of 4.0 h⁻¹. -1 The reaction products were analyzed and calculated using gas chromatography; the results are shown in Figure 2.

[0119] Table 2

[0120]

[0121] *Data from a 72-hour reaction time.

[0122] **Reaction time for cyclohexene conversion > 99.8%.

[0123]

Application Example 3

[0124] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene under the catalysis of the catalyst prepared above. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 10. The water content, total nitrogen content, and total sulfur content of the raw materials were 15 mg / kg, 0.03 mg / kg, and 0.05 mg / kg, respectively. The catalyst prepared in Example 1 and Comparative Example 1 was loaded into a fixed-bed reactor at a loading amount of 3.0 g. Under the conditions of reaction temperature 170 °C and pressure 2.0 MPa, the pretreated raw materials prepared above were introduced at a flow rate of 6.0 g / h, i.e., a raw material space velocity of 2.0 h⁻¹. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 3.

[0125] Table 3

[0126]

[0127] *Data from a 72-hour reaction time.

[0128] **Reaction time for cyclohexene conversion > 99.8%.

[0129] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst for the alkylation of benzene with cyclohexene to produce cyclohexylbenzene, the catalyst comprising an ultrathin layered MWW molecular sieve and a heteropolyacid, wherein the layer thickness of the ultrathin layered MWW molecular sieve is 5-10 nm; the SiO2 / Al2O3 molar ratio of the ultrathin layered MWW molecular sieve is 10-100; the heteropolyacid is one or more selected from phosphotungstic acid, silicotungstic acid, and phosphomolybdic acid; and the preparation method of the ultrathin layered MWW molecular sieve includes: A silicon source, an aluminum source, an alkali source, water, a first template agent T1, and a second template agent T2 are mixed and crystallized to obtain an ultrathin layered MWW molecular sieve. The first template agent T1 is selected from at least one of hexamethyleneimine, tetrahydropyrrole, hexahydropyridine, 2-methylhexahydropyridine, or heptamethyleneimine. The second template agent T2 is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, dialcyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, and octadecyltrimethylammonium bromide.

2. The catalyst according to claim 1, characterized in that: The heteropoly acid is phosphotungstic acid.

3. The catalyst according to claim 1, characterized in that: The ultrathin layered MWW molecular sieve has a SiO2 / Al2O3 molar ratio of 20 to 40.

4. The catalyst according to claim 1, characterized in that: The catalyst includes a binder, which is one or more of alumina or silicon dioxide.

5. The catalyst according to claim 1, characterized in that: In the catalyst, the content of binder, calculated as oxide, is 3% to 15% based on the weight of the catalyst.

6. The catalyst according to claim 5, characterized in that: In the catalyst, the binder content, calculated as oxides, is 5% to 10% based on the weight of the catalyst.

7. The catalyst according to claim 1, characterized in that: In the catalyst, the content of heteropoly acid, based on the total weight of MWW molecular sieve and binder (calculated as oxides), is 10wt% to 100wt% of anhydrous heteropoly acid molecules.

8. The catalyst according to claim 7, characterized in that: In the catalyst, the content of heteropoly acid, based on the total weight of MWW molecular sieve and binder as oxides, is 40wt%~80wt% based on anhydrous heteropoly acid molecules.

9. A method for preparing the catalyst according to any one of claims 1-8, comprising the following steps: (1) Mix silicon source, aluminum source, alkali source, water, first template agent T1 and second template agent T2, crystallize, and obtain ultrathin layered MWW molecular sieve; (2) The ultrathin layered MWW molecular sieve obtained in step (1) is subjected to acid exchange, molding, and calcination to obtain a catalyst intermediate; (3) The catalyst intermediate obtained in step (2) is impregnated with a heteropoly acid aqueous solution in the presence of a surfactant and then calcined to obtain the catalyst.

10. The preparation method according to claim 9, characterized in that: The first template agent T1 is selected from at least one of hexamethyleneimine, tetrahydropyrrole, hexahydropyridine, 2-methylhexahydropyridine, or heptamethyleneimine; the second template agent T2 is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, dialcyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, or octadecyltrimethylammonium bromide. And / or, the silicon source is selected from at least one of silicon dioxide, silica sol, fumed silica, water glass, sodium silicate, or tetraethyl silicate; And / or, the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, aluminum isopropoxide, aluminum sol, or aluminum hydroxide; And / or, the alkali source is selected from at least one of sodium hydroxide or potassium hydroxide.

11. The preparation method according to claim 10, characterized in that: The first template agent T1 is at least one of hexamethyleneimine and hexahydropyridine; the second template agent T2 is at least one of hexadecyltrimethylammonium bromide and dodecyltrimethylammonium chloride; and / or, the silicon source is silicon dioxide; and / or, the aluminum source is aluminum nitrate; and / or, the alkali source is sodium hydroxide.

12. The preparation method according to claim 9, characterized in that: In step (1), the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali as OH. - The molar ratio of the feed materials is calculated to be: SiO2 / Al2O3 = 10~100; OH - The ratio of H2O / SiO2 is 0~0.40; the ratio of H2O / SiO2 is 10~50; the ratio of the first template agent T1 / SiO2 is 0.05~1.0; and the ratio of the second template agent T2 / SiO2 is 0.001~0.

1.

13. The preparation method according to claim 12, characterized in that: In step (1), the silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali as OH. - The molar ratio of the feed materials is calculated to be: SiO2 / Al2O3 = 20~40; OH - The ratio of H2O / SiO2 is 0.05~0.15; the ratio of H2O / SiO2 is 20~30; the ratio of the first template agent T1 / SiO2 is 0.1~0.5; and the ratio of the second template agent T2 / SiO2 is 0.01~0.

04.

14. The preparation method according to claim 9, characterized in that: In step (1), the crystallization is performed using dynamic crystallization with a stirring rate of 10-200 rpm, a crystallization temperature of 100-200°C, and a crystallization time of 24-144 h. And / or, in step (2), the acid exchange conditions include: temperature of 20~100°C; time of 0.5~24h / time; acid concentration of 0.001~2mol / L; and acid exchange times of 1~6 times. And / or, in step (2), the calcination temperature is 350~650°C and the calcination time is 1~10h; And / or, in step (3), the calcination conditions are: temperature of 350~550°C and time of 1~12h.

15. The preparation method according to claim 14, characterized in that: In step (1), the stirring rate is 20~100 rpm; the crystallization temperature is 150~180°C; and the crystallization time is 48~96 h. And / or, in step (2), the acid exchange conditions include: temperature of 65~95°C; time of 3~8h / time; acid concentration of 0.01~0.5mol / L; and acid exchange times of 2~4 times. And / or, in step (2), the calcination temperature is 500~600°C and the calcination time is 2~8h; And / or, in step (3), the calcination conditions are: temperature of 400~500°C and time of 3~6h.

16. The preparation method according to claim 9, characterized in that: In step (2), the acid is an organic acid and / or an inorganic acid; And / or, in step (2), the binder used in the molding process is at least one of boehmite, silica sol, γ-alumina, aluminum hydroxide or silica; And / or, in step (3), the surfactant is at least one of a nonionic surfactant or anionic surfactant; the anionic surfactant is one or more of hexadecylbenzenesulfonic acid, hexadecyltrimethyl-p-toluenesulfonic acid, and dodecylbenzenesulfonic acid.

17. The preparation method according to claim 16, characterized in that: In step (2), the acid is at least one of oxalic acid, citric acid, formic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, and hydrochloric acid; And / or, in step (2), the binder used in the molding process is boehmite or silica sol; And / or, in step (3), the nonionic surfactant is poly(ethylene glycol). x -Propylene glycol y - Ethylene glycol z The triblock oligomer has a molecular weight of 1100-14600; the anionic surfactant is one or more of hexadecylbenzenesulfonic acid, hexadecyltrimethyl-p-toluenesulfonic acid, and dodecylbenzenesulfonic acid.

18. The preparation method according to claim 17, characterized in that: Poly(ethylene glycol) x -Propylene glycol y - Ethylene glycol z The molecular weight of triblock oligomers is 4400~8000.

19. The preparation method according to claim 9, characterized in that: In step (2), the mass ratio of acid solution to molecular sieve is 2~20; And / or, in step (3), the mass ratio of surfactant to MWW-type molecular sieve is 0.001~0.10; And / or, in step (3), the mass concentration of the heteropolyacid aqueous solution is 8.3%~83.3%.

20. The preparation method according to claim 19, characterized in that: In step (2), the mass ratio of acid solution to molecular sieve is 5~10; And / or, in step (3), the mass ratio of surfactant to MWW-type molecular sieve is 0.01~0.05; And / or, in step (3), the mass concentration of the heteropolyacid aqueous solution is 33.3%~66.7%.

21. A method for preparing cyclohexylbenzene by alkylation of benzene and cyclohexene, comprising alkylating benzene and cyclohexene on any one of the catalysts described in claims 1-8 to obtain cyclohexylbenzene.

22. The method according to claim 21, characterized in that: The molar ratio of benzene to cyclohexene is 3 to 30; And / or, the water content in the raw materials benzene and cyclohexene is <100 mg / kg; the total nitrogen content is <0.1 mg / kg; and the total sulfur content is <0.1 mg / kg. And / or, the total mass hourly space velocity (MHV) of benzene and cyclohexene is 0.1–6.0 h⁻¹. -1 The reaction pressure is 1.0~4.0 MPa; the reaction temperature is 80~200°C.

23. The method according to claim 22, characterized in that: The molar ratio of benzene to cyclohexene is 5-15; And / or, the water content in the raw materials benzene and cyclohexene is <50 mg / kg; the total nitrogen content is <0.05 mg / kg; and the total sulfur content is <0.05 mg / kg. And / or, the total mass hourly space velocity (WHSV) of benzene and cyclohexene is 1.0–4.0 h⁻¹. -1 The reaction pressure is 1.5~2.5MPa; the reaction temperature is 110~150°C.

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