A process for the production of cyclohexylbenzene

Abstract

The application discloses a production method of cyclohexylbenzene. The method is to use benzene and dicyclohexylbenzene as raw materials, metal / USY molecular sieve as a catalyst, and hydrogen gas to generate an alkyl transfer reaction to obtain cyclohexylbenzene, wherein the molar ratio of hydrogen to benzene is 0.1-1.0. The method can obtain higher conversion rate of dicyclohexylbenzene and selectivity of cyclohexylbenzene at a lower reaction temperature, and improves the yield of cyclohexylbenzene.

Description

Technical Field

[0001] This invention relates to the field of fine chemical production technology, specifically to a method for producing cyclohexylbenzene from benzene and dicyclohexylbenzene under hydrogen-assisted alkyl transfer. Background Technology

[0002] Cyclohexylbenzene (CHB) can be used to prepare phenol and cyclohexanone through oxidation and acid decomposition reactions. It can partially replace the existing process of preparing phenol by cumene and alleviate the problem of overcapacity in the co-production of acetone. It is a fine chemical with high added value.

[0003] Cyclohexylbenzene can be prepared by Friedel-Crafts alkylation of benzene, hydrogenation of biphenyl, or hydrogenation alkylation of benzene. CN105367371A, CN106518600A, CN108530247A, CN103848710A, CN103848711A, CN104513122A, CN104513123A, etc. disclose some methods for preparing cyclohexylbenzene by Friedel-Crafts alkylation of benzene; CN104105679A, CN110563534A, CN107930682A, CN105233862A, etc. disclose some catalysts or methods for the direct hydrogenation alkylation of benzene to prepare cyclohexylbenzene; CN107185548A, CN107008477A, ​​CN1800121A, etc. disclose some methods for preparing cyclohexylbenzene by selective hydrogenation of biphenyl. All of the above methods will inevitably produce secondary alkylation products—dicyclohexylbenzene, which includes three isomers: 1,4-dicyclohexylbenzene, 1,3-dicyclohexylbenzene, and 1,2-dicyclohexylbenzene. Cyclohexylbenzene can be recovered through alkyl transfer reactions with benzene.

[0004] CN102448915A discloses a method for alkyl transfer from polycyclohexylbenzene to benzene, using a USY-type zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 60 as a catalyst, at a reaction temperature of 170℃ (150~200℃), a pressure of 2.17MPa (1.5~3.0MPa), a benzene / dicyclohexylbenzene molar ratio of 9.1 (weight ratio 6), and a total mass hourly space velocity of 4h⁻¹. -1 Under the same conditions, after 576 h of reaction, the conversion rate of dicyclohexylbenzene was 63%, the selectivity of cyclohexylbenzene was 97.5%, and the selectivity of the key impurity methylcyclopentylbenzene was 1.2%. CN103848710A and CN104513123A disclose a method for preparing cyclohexylbenzene from benzene via alkyl transfer reaction, with a reaction temperature of 160℃ (150–240℃), a pressure of 3.0 MPa (2.0–3.0 MPa), a benzene to polycyclohexylbenzene molar ratio of 15 (weight ratio 9.9), and a total mass hourly space velocity of 2.0 h⁻¹. -1Under the same conditions, the conversion rate of dicyclohexylbenzene was 66.5%. No data on the selectivity of cyclohexylbenzene or methylcyclopentylbenzene or catalyst lifetime were reported.

[0005] Due to the large molecular size of both the reactant dicyclohexylbenzene and the product cyclohexylbenzene, molecular sieves are prone to pore blockage when used as catalysts, leading to catalyst deactivation. While increasing the reaction temperature can promote the diffusion of these molecules, it also increases side reactions and enhances the selectivity of 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

[0006] To address the prominent problems in existing technologies regarding the alkyl transfer reaction of benzene with polycyclohexylbenzene, such as high reaction temperature, low selectivity of cyclohexylbenzene, high selectivity of the byproduct methylcyclopentylbenzene, and short catalyst lifetime, this invention provides a novel method for producing cyclohexylbenzene. This method can reduce the formation of the key impurity methylcyclopentylbenzene and extend its lifespan, allowing the alkyl transfer reaction of benzene with dicyclohexylbenzene to proceed at a lower reaction temperature.

[0007] This invention provides a method for producing cyclohexylbenzene, which uses benzene and dicyclohexylbenzene as raw materials, a metal / USY molecular sieve as a catalyst, and an alkyl transfer reaction under a hydrogen atmosphere to produce cyclohexylbenzene. The molar ratio of hydrogen to benzene is 0.1 to 1.0, preferably 0.2 to 0.6.

[0008] Furthermore, the method employs a fixed-bed reactor.

[0009] Furthermore, the metal is silver and / or copper.

[0010] Furthermore, the SiO2 / Al2O3 molar ratio of the USY molecular sieve is 8–120, preferably 10–50.

[0011] Furthermore, in the catalyst, based on the mass of the catalyst, the content of metal as an element is 0.01% to 0.30%, preferably 0.04% to 0.16%, and the content of USY molecular sieve is 80% to 95%.

[0012] Furthermore, the catalyst also includes a binder, the content of which, based on the weight of the catalyst, is 5% to 20% (calculated as oxides), preferably 7% to 15%. The binder is preferably at least one of alumina or silica.

[0013] Furthermore, the total mass hourly space velocity (MHSV) of the feedstock benzene and dicyclohexylbenzene is 0.1–6.0 h⁻¹. -1 Preferably, it is 1.0 to 4.0 h.-1 .

[0014] Furthermore, the alkyl transfer reaction pressure is 1.0–4.0 MPa, preferably 1.5–2.5 MPa.

[0015] Furthermore, the alkyl transfer reaction temperature is 70–160°C, preferably 100–140°C.

[0016] Furthermore, the catalyst is packed in a fixed-bed reactor and pre-reduced under a hydrogen atmosphere. The pre-reduction temperature is 100–400°C, preferably 150–300°C, and the pre-reduction time is 0.1–10 h, preferably 1–5 h.

[0017] Furthermore, in the method for producing cyclohexylbenzene by alkyl transfer from benzene and dicyclohexylbenzene, the molar ratio of benzene to dicyclohexylbenzene is 3 to 30, preferably 6 to 15; the water content in the raw materials benzene and dicyclohexylbenzene 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.

[0018] Furthermore, in the method for producing cyclohexylbenzene from benzene via alkyl transfer from dicyclohexylbenzene, the raw materials benzene and dicyclohexylbenzene may be selectively pretreated with dehydration and dealkalization based on their impurity content. This pretreatment can be carried out using an adsorption method, for example, employing 13X molecular sieve as the adsorbent.

[0019] Furthermore, the catalyst is prepared by: subjecting USY molecular sieve to acid treatment, impregnation, molding, and calcination to obtain the catalyst.

[0020] Furthermore, the cell parameters of the USY molecular sieve are ≤2.450 nm, preferably 2.428–2.443 nm.

[0021] Further, the acid treatment conditions include: a temperature of 20–100°C, preferably 65–95°C; a treatment 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; 1–6 acid treatments, preferably 2–4 treatments; and a mass ratio of acid solution to molecular sieve of 2–20, preferably 5–10.

[0022] Further, the acid is an organic acid and / or an inorganic acid, and the acid is at least one selected from oxalic acid, citric acid, formic acid, acetic acid, propionic acid, sulfuric acid, nitric acid and hydrochloric acid, preferably at least one selected from sulfuric acid, nitric acid and hydrochloric acid.

[0023] Furthermore, the silver salt used in the impregnation process is silver nitrate, and the copper salt is at least one of copper nitrate or copper sulfate. The mass concentration of the metal salt solution is 0.01% to 0.46%, preferably 0.03% to 0.25%.

[0024] Further, the impregnation process includes: dissolving silver salt and / or copper salt in deionized water, impregnating the USY molecular sieve sample with an equal volume, and drying. The impregnation time is 1–12 h, preferably 2–8 h; the drying temperature is 50–150 °C, preferably 80–120 °C; and the drying time is 2–48 h, preferably 6–24 h.

[0025] Furthermore, the binder used in the molding process is at least one of boehmite, silica sol, γ-alumina, aluminum hydroxide, and silica, preferably boehmite or silica sol. The binder, calculated as an oxide, has a weight content of 5% to 20% in the catalyst, preferably 7% to 15%.

[0026] Furthermore, the calcination temperature is 350–650°C, preferably 500–600°C, and the calcination time is 1–10 h, preferably 2–8 h.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) This invention provides a novel method for the alkyl transfer reaction of benzene with dicyclohexylbenzene to prepare cyclohexylbenzene, using a USY molecular sieve supported on silver and / or copper as a catalyst under hydrogen-assisted conditions. The catalyst using this method exhibits better alkyl transfer activity and selectivity, allowing the reaction of benzene with dicyclohexylbenzene to proceed at a lower reaction temperature. The selectivity of the key byproduct methylcyclopentanebenzene is significantly reduced, resulting in a substantial decrease in separation energy consumption and improved purity of the cyclohexylbenzene product.

[0029] (2) By introducing hydrogen and modifying the catalyst, the present invention can delay the rate of catalyst deactivation due to coking, thereby extending the catalyst life and meeting the requirements of industrial applications. Attached Figure Description

[0030] Figure 1 XRD pattern of catalyst Y2 synthesized in Example 2;

[0031] Figure 2 TEM image of catalyst Y2 synthesized in Example 2. Detailed Implementation

[0032] The present invention will be further illustrated below through examples.

[0033] 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.

[0034] In this invention, TEM images of the catalyst were taken using a JEOL-2010F electron microscope; TEM images were observed using a FEINova NanoSEM 450 electron microscope.

[0035] In this invention, the products of the alkyl transfer reaction between benzene and dicyclohexylbenzene are analyzed by gas chromatography-FID, and key indicators such as the conversion rate of dicyclohexylbenzene, the selectivity of cyclohexylbenzene, and the selectivity of methylcyclopentanehexylbenzene are calculated according to the following formulas:

[0036] Dicyclohexylbenzene conversion rate = (mass percentage of dicyclohexylbenzene before reaction - mass percentage of dicyclohexylbenzene after reaction) / (mass percentage of dicyclohexylbenzene before reaction) × 100%;

[0037] Cyclohexylbenzene selectivity = (mass percentage of cyclohexylbenzene) / (sum of mass percentages of all products and byproducts) × 100%;

[0038] Selectivity of methylcyclopentylbenzene = (mass percentage of methylcyclopentylbenzene) / (sum of mass percentages of all products and byproducts) × 100%.

[0039]

Example 1

[0040] Commercially available USY-type molecular sieves (SiO2 / Al2O3 molar ratio 23.5, cell parameter 2.4391 nm) were selected and acid-treated in 0.2 mol / L hydrochloric acid solution at 80℃ for 5 hours per treatment, for a total of 4 treatments. After washing and drying, silver nitrate solution (0.07% by mass) was added and impregnated by equal volume for 6 hours, followed by drying at 95℃ for 12 hours. Phobospore 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 phiobospore added was 10% of the total catalyst weight on a dry basis. The strips were calcined in air at 525℃ for 5 hours to prepare an alkyl transfer catalyst, designated Y1, with a silver content of 0.04%.

[0041]

Example 2

[0042] The only difference from Example 1 is that the mass percentage concentration of the silver nitrate solution is 0.13%.

[0043] The alkyl transfer catalyst prepared in Example 2, designated Y2, contains 0.08% silver.

[0044]

Example 3

[0045] The only difference from Example 1 is that the mass percentage concentration of the silver nitrate solution is 0.25%.

[0046] The alkyl transfer catalyst prepared in Example 3, designated Y3, contains 0.16% silver.

[0047]

Example 4

[0048] Commercially available USY-type molecular sieves (SiO2 / Al2O3 molar ratio 23.5, cell parameter 2.4391 nm) were selected and acid-treated in 0.2 mol / L hydrochloric acid solution at 80℃ for 5 hours per treatment, for a total of 4 treatments. After washing and drying, copper nitrate solution (0.13% by mass) was added and impregnated by equal volume for 6 hours, followed by drying at 95℃ for 12 hours. Phobophyllite 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 phiophyllite added was 10% of the total catalyst weight on a dry basis. The strips were calcined in air at 525℃ for 5 hours to prepare alkyl transfer catalysts, designated Y4, with a copper content of 0.04%.

[0049]

Example 5

[0050] The only difference from Example 4 is that the mass percentage concentration of the copper nitrate solution is 0.25%.

[0051] The alkyl transfer catalyst prepared in Example 5, designated Y5, contains 0.08% copper.

[0052]

Example 6

[0053] The only difference from Example 4 is that the mass percentage concentration of the copper nitrate solution is 0.45%.

[0054] The alkyl transfer catalyst prepared in Example 6, designated Y6, contains 0.16% copper.

[0055]

Example 7

[0056] Compared with Example 2, the only difference is that the acid exchange conditions are changed: the USY type molecular sieve is acid-treated in a 0.375 mol / L hydrochloric acid solution at a temperature of 70°C for 7 hours per treatment, for a total of 4 treatments. After washing and drying, silver nitrate solution with a mass percentage concentration of 0.13% is added, and the mixture is impregnated for 12 hours at an equal volume, followed by drying at 105°C for 8 hours.

[0057] The alkyl transfer catalyst prepared in Example 7, designated Y7, contains 0.08% silver.

[0058]

Example 8

[0059] The only difference from Example 2 is that the content of the binder boehmite in the molding process is changed to 13.5%.

[0060] The alkyl transfer catalyst prepared in Example 8, designated Y8, contains 0.08% silver.

[0061]

Example 9

[0062] The only difference from Example 2 is that the SiO2 / Al2O3 molar ratio of the USY type molecular sieve is 46, and the cell parameter is 2.4342 nm.

[0063] The alkyl transfer catalyst prepared in Example 9, designated Y9, contains 0.08% silver.

[0064]

Example 10

[0065] The only difference from Example 2 is that the SiO2 / Al2O3 molar ratio of the USY type molecular sieve is 90.7 and the cell parameter is 2.4299 nm.

[0066] The alkyl transfer catalyst prepared in Example 10, designated Y10, contains 0.08% silver.

[0067]

Example 11

[0068] Compared with Example 2, the only difference is that the USY type molecular sieve (SiO2 / Al2O3 molar ratio 23.5, cell parameter 2.4391nm) is acid-treated in 0.2mol / L citric acid solution at a temperature of 80℃ for 5h / time, for a total of 4 treatments.

[0069] The alkyl transfer catalyst prepared in Example 11, designated Y11, contains 0.08% silver.

[0070]

Example 12

[0071] The only difference from Example 2 is that the SiO2 / Al2O3 molar ratio of the USY type molecular sieve is 9.8, and the cell parameter is 2.4488 nm.

[0072] The alkyl transfer catalyst prepared in Example 12, designated Y12, contains 0.08% silver.

[0073] Comparative Example 1

[0074] Commercially available USY-type molecular sieves (SiO2 / Al2O3 molar ratio 23.5, cell parameter 2.4391 nm) were selected and acid-treated in 0.2 mol / L hydrochloric acid solution at 80℃ for 5 hours per treatment, for a total of 4 treatments. Boehmite 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 boehmite added was 10% of the total catalyst weight on a dry basis. The strips were then calcined in air at 525℃ for 5 hours to prepare the alkyl transfer catalyst C1.

[0075] Comparative Example 2

[0076] Cyclohexylbenzene was prepared using the method described in CN102448915A.

[0077] Commercially available USY molecular sieve (SiO2 / Al2O3 = 60, cell parameter 2.4329 nm), boehmite, 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 boehmite added was 30% of the total weight of the catalyst on a dry basis. The mixture was calcined in air at 525 °C for 5 h to prepare alkyl transfer catalyst C2.

[0078] Comparative Example 3

[0079] Cyclohexylbenzene was synthesized using the method described in CN103848710A.

[0080] Commercially available USY-type molecular sieve (SiO2 / Al2O3 = 7.5, cell parameter 2.4552nm), pseudoboehmite, and dilute nitric acid were mixed and molded to form catalyst cylindrical strips with a diameter of 1.5mm and a length of 3-10mm. The amount of pseudoboehmite added was calculated on a dry basis and accounted for 30% of the total weight of the catalyst. The mixture was calcined in air at 525℃ for 5 hours to prepare alkyl transfer catalyst C3.

[0081]

Application Example 1

[0082] In the presence of hydrogen, benzene and dicyclohexylbenzene were subjected to an alkyl transfer reaction to prepare cyclohexylbenzene under the catalysis of the catalyst prepared above. The raw materials, benzene and dicyclohexylbenzene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to dicyclohexylbenzene was 10. The water content, total nitrogen content, and total sulfur content of the raw materials were 23 mg / kg, 0.03 mg / kg, and 0.06 mg / kg, respectively. The catalysts prepared in Examples 1-12 and Comparative Examples 1-3 were respectively loaded into fixed-bed reactors at a loading amount of 3.0 g. Pre-reduction was first carried out under atmospheric pressure and hydrogen conditions at a reduction temperature of 250°C for 4 h. The temperature was then lowered to 120°C, the pressure increased to 2.0 MPa, and the pretreated raw materials prepared above were introduced at a hydrogen / benzene molar ratio of 0.5 at a flow rate of 9.0 g / h, i.e., a raw material space velocity of 3.0 h⁻¹. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 1.

[0083] Table 1

[0084]

[0085] *Data after 72 hours of reaction.

[0086] **Total reaction time for dicyclohexylbenzene conversion greater than 50%.

[0087]

Application Example 2

[0088] In the presence of hydrogen, benzene and dicyclohexylbenzene were subjected to an alkyl transfer reaction to prepare cyclohexylbenzene under the catalysis of the catalyst prepared above. The raw materials, benzene and dicyclohexylbenzene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to dicyclohexylbenzene was 7.5. The water content, total nitrogen content, and total sulfur content of the raw materials were 29 mg / kg, 0.03 mg / kg, and 0.07 mg / kg, respectively. The catalysts prepared in Example 2 and Comparative Example 1 were loaded into fixed-bed reactors at a loading amount of 3.0 g. Pre-reduction was first performed under atmospheric pressure and hydrogen conditions at 250°C for 4 h. The temperature was then lowered to 130°C, the pressure increased to 2.2 MPa, and the pretreated raw materials were introduced at a flow rate of 10.5 g / h (i.e., a raw material space velocity of 3.5 h⁻¹) according to a hydrogen / benzene molar ratio of 0.4. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 2.

[0089] Table 2

[0090]

[0091] *Data after 72 hours of reaction.

[0092] **Total reaction time for dicyclohexylbenzene conversion greater than 50%.

[0093]

Application Example 3

[0094] In the presence of hydrogen, benzene and dicyclohexylbenzene were subjected to an alkyl transfer reaction to prepare cyclohexylbenzene under the catalysis of the catalyst prepared above. The raw materials, benzene and dicyclohexylbenzene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to dicyclohexylbenzene was 20. The water content, total nitrogen content, and total sulfur content of the raw materials were 29 mg / kg, 0.03 mg / kg, and 0.07 mg / kg, respectively. The catalysts prepared in Example 2 and Comparative Example 1 were loaded into fixed-bed reactors at a loading amount of 3.0 g. Pre-reduction was first performed under atmospheric pressure and hydrogen conditions at 250°C for 4 h. The temperature was then lowered to 150°C, the pressure increased to 3.5 MPa, and the pretreated raw materials were introduced at a flow rate of 15.0 g / h (i.e., a raw material space velocity of 5.0 h⁻¹) according to a hydrogen / benzene molar ratio of 0.8. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 3.

[0095] Table 3

[0096]

[0097] *Data after 72 hours of reaction.

[0098] **Total reaction time for dicyclohexylbenzene conversion greater than 50%.

[0099]

Comparative Application Example 1

[0100] Cyclohexylbenzene was prepared by alkyl transfer reaction of benzene and dicyclohexylbenzene under the catalysis of the catalyst described above, without the addition of hydrogen. The raw materials, benzene and dicyclohexylbenzene, were pretreated with 13X molecular sieves for dehydration and removal of alkalis, and then thoroughly mixed. The weight ratio of benzene to dicyclohexylbenzene was 10. The water content of the raw materials was 23 mg / kg, the total nitrogen content was 0.03 mg / kg, and the total sulfur content was 0.06 mg / kg. The catalyst prepared in Example 2 was loaded into a fixed-bed reactor at a loading amount of 3.0 g. The temperature was adjusted to 120°C, the pressure was increased to 2.0 MPa, and 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 4.

[0101] Table 4

[0102]

[0103] *Data after 72 hours of reaction.

[0104] **Total reaction time for dicyclohexylbenzene conversion greater than 50%.

[0105]

Comparative Application Example 2

[0106] In the presence of hydrogen, benzene and dicyclohexylbenzene were subjected to an alkyl transfer reaction to prepare cyclohexylbenzene under the catalysis of the catalyst prepared above. The raw materials, benzene and dicyclohexylbenzene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to dicyclohexylbenzene was 10. The water content in the raw materials was 23 mg / kg, the total nitrogen content was 0.03 mg / kg, and the total sulfur content was 0.06 mg / kg. The catalyst prepared in Example 2 was loaded into a fixed-bed reactor at a loading of 3.0 g. Pre-reduction was first performed under atmospheric pressure and hydrogen conditions at 250°C for 4 h. The temperature was then lowered to 170°C, the pressure increased to 2.0 MPa, and the pretreated raw materials were introduced at a hydrogen / benzene molar ratio of 0.5 at a flow rate of 9.0 g / h (i.e., a raw material space velocity of 3.0 h⁻¹). -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 5.

[0107] Table 5

[0108]

[0109] *Data after 72 hours of reaction.

[0110] **Total reaction time for dicyclohexylbenzene conversion greater than 50%.

[0111] 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 process for the production of cyclohexylbenzene, which comprises subjecting benzene and dicyclohexylbenzene to transalkylation in the presence of a metal / USY molecular sieve catalyst under a hydrogen atmosphere, wherein, the benzene and dicyclohexylbenzene are obtained by the process according to claim 1. The molar ratio of hydrogen to benzene is 0.1-1.0, and the transalkylation reaction temperature is 70-160 °C; the catalyst is pre-reduced before reaction, the reducing gas is hydrogen, the pre-reduction temperature is 100-400 °C, and the pre-reduction time is 0.1-10 h; the molar ratio of SiO2 / Al2O3 of the USY molecular sieve is 8-120, and the metal is silver and / or copper.

2. The production method according to claim 1, characterized by, The molar ratio of hydrogen to benzene is 0.2-0.

6.

3. The production method according to claim 1, characterized by, The method uses a fixed bed reactor.

4. The production method according to claim 1, characterized by, The molar ratio of SiO2 / Al2O3 of the USY molecular sieve is 10-50.

5. The production method according to claim 1, characterized by, In the catalyst, the content of the metal, calculated as an element, is 0.01%-0.30% based on the mass of the catalyst, and the content of the USY molecular sieve is 80%-95%.

6. The production method according to claim 5, characterized by, In the catalyst, the content of the metal, calculated as an element, is 0.04%-0.16% based on the mass of the catalyst.

7. The production method according to claim 1, characterized by, The catalyst comprises a binder, and the content of the binder, calculated as an oxide, is 5%-20% based on the weight of the catalyst.

8. The production method according to claim 7, characterized by, The catalyst comprises a binder, and the content of the binder, calculated as an oxide, is 7%-15% based on the weight of the catalyst.

9. The production method according to claim 7, characterized by, The binder is at least one of alumina and silica.

10. The production method according to claim 1, characterized by, The pre-reduction temperature is 150-300 °C, and the pre-reduction time is 1-5 h.

11. The production method according to claim 1, characterized by, The molar ratio of benzene to dicyclohexylbenzene is 3-30; and / or, the water content in the raw benzene and dicyclohexylbenzene is <100 mg / kg; the total nitrogen content is <0.1 mg / kg; and the total sulfur content is <0.1 mg / kg.

12. The production method according to claim 1, characterized by, The molar ratio of benzene to dicyclohexylbenzene is 6-15; and / or, the water content in the raw benzene and dicyclohexylbenzene is <50 mg / kg; the total nitrogen content is <0.05 mg / kg; and the total sulfur content is <0.05 mg / kg.

13. The production method according to claim 1, characterized by, The benzene and dicyclohexylbenzene are subjected to dehydration and alkaline substance removal treatment.

14. The production method according to claim 1, characterized by, The total mass space velocity of benzene and dicyclohexylbenzene is 0.1-6.0 h -1 ; the transalkylation reaction pressure is 1.0-4.0 MPa; and the transalkylation reaction temperature is 100-140 °C.

15. The production method according to claim 14, characterized by, The total mass space velocity of benzene and dicyclohexylbenzene is 1.0-4.0 h -1 ; the transalkylation reaction pressure is 1.5-2.5 MPa.

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