A method for producing BTX by LCO hydrocracking

Abstract

This invention discloses a method for producing BTX by LCO hydrocracking. The method includes the reaction stream LCO being successively fed into a hydrorefining reactor and a hydrocracking reactor. The hydrocracking reactor has a low-temperature hydrorefining zone and a high-temperature hydrorefining zone along the stream direction. The hydrocracking reactor also has a hydrogenation ring-opening zone, a dealkylation reaction zone, and an alkyl transfer reaction zone along the stream direction. The reactants are separated to obtain BTX. This method utilizes a zoned, intensified hydrocracking process to achieve LCO-guided conversion for direct production of light aromatics. This method has a short process flow, improves the yield of light aromatics, reduces side reactions such as aromatic condensation carbon deposition and aromatic saturation, and extends the operating cycle.

Description

Technical Field

[0001] This invention relates to the field of LCO comprehensive utilization, and to a method for producing high-value products by LCO hydrocracking, specifically a method for producing high-value products BTX by LCO hydrocracking. Background Technology

[0002] Light-cycle crude oil (LCO) from catalytic cracking is one of the main byproducts of the catalytic cracking process, with a yield of approximately 25%. Currently, domestic LCO production exceeds 50 million tons per year. LCO is characterized by high density, high aromatic content, and low cetane number. In the era when the quality requirements for automotive diesel were not high, LCO was commonly used as a blending component. However, with the increasing quality standards for automotive diesel, LCO is no longer suitable as a blending component. Therefore, how to utilize the aromatics in LCO to produce high-value-added petroleum products or chemical feedstocks has attracted considerable attention.

[0003] CN201811246834.5 combines the hydrocracking and catalytic cracking processes of LCO, subjecting the light and middle fraction LCO, a product of catalytic cracking, to hydrocracking, and the heavy fraction LCO, a product of catalytic cracking, to residue hydrogenation. Using the method of this invention, high-value gasoline blending components and other chemical products can be produced.

[0004] CN201510664856.3 describes a process where LCO is mixed with hydrogen and fed into a hydrotreating reactor to remove sulfur and nitrogen impurities, converting polycyclic aromatic hydrocarbons (PAHs) into monocyclic aromatic hydrocarbons (MAHs). The reaction effluent undergoes oil-gas separation and fractionation; the heavy fraction is directly used as diesel fuel, while the middle fraction, recycled toluene, and recycled C9 are processed into diesel fuel. + Aromatics are mixed with hydrogen and introduced into the reactor. The reaction products are sent to the fractionation system. In the fractionation system, benzene and other products are discharged off-site, while toluene and C9 are discharged off-site. + The technical solution of recycling fraction A back to the middle fraction conversion reactor, discharging benzene and xylene as products outside the boundary, and recycling the heavy fraction from the bottom of the tower back to the hydrogenation treatment reactor can be used in the industrial production of benzene and xylene from LCO feedstock.

[0005] The existing LCO conversion methods integrate multiple processes such as hydrogenation, FCC, and alkyl transfer, resulting in a long process flow, complex operation, numerous aromatic condensation side reactions, and short catalyst lifetime. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for producing BTX via LCO hydrocracking. This method utilizes a partitioned, intensified hydrocracking process to achieve LCO-guided conversion directly to produce light aromatics. This method has a short process flow, improves the yield of light aromatics, reduces side reactions such as aromatic condensation carbon deposition and aromatic saturation, and extends the operating cycle.

[0007] A method for producing BTX by LCO hydrocracking, the method comprising feeding LCO reaction stream into a hydrorefining reactor and a hydrocracking reactor sequentially, wherein the hydrocracking reactor is provided with a low-temperature hydrorefining zone and a high-temperature hydrorefining zone along the stream direction, and the hydrocracking reactor is provided with a hydroring-opening zone, a dealkylation reaction zone and an alkyl transfer reaction zone along the stream direction, and the reacted material is separated to obtain BTX.

[0008] Furthermore, the LCO has the following properties: density at 20℃ is 0.85~1.00 kg / cm³. 3 The sulfur content is 30ppm~20000ppm, and the nitrogen content is 30ppm~1000ppm.

[0009] Furthermore, the reaction conditions of the hydrorefining reactor are as follows: reaction pressure of 4.0~10.0 MPa, preferably 5.0~8.0 MPa; hydrogen-to-oil volume ratio of 300:1~600:1, preferably 400:1~500:1; and liquid hourly space velocity of 0.25~3.0 h⁻¹. -1 Preferably 0.5~2.0h -1 .

[0010] Furthermore, the low-temperature hydrorefining zone completes hydrodenitrification, hydrodesulfurization, and hydrogen saturation of polycyclic aromatic hydrocarbons to obtain monocyclic aromatic hydrocarbons, which can remove most of the easily removable nitrogen compounds; the high-temperature hydrorefining zone completes deep denitrification under the condition of minimizing aromatic hydrocarbon loss; the volume ratio of the low-temperature hydrorefining zone to the high-temperature hydrorefining zone is 3:7~7:3.

[0011] Furthermore, the reaction temperature of the low-temperature hydrogenation refining zone is 300~350℃, preferably 320~340℃; the reaction temperature of the high-temperature hydrogenation refining zone is 370~420℃, preferably 390~410℃.

[0012] Furthermore, the hydrorefining reactor is filled with a commercial hydrorefining catalyst, preferably a non-precious metal hydrorefining catalyst, such as FF-56 and FF-66 developed by the Fushun Petrochemical Research Institute. The catalysts filled in the low-temperature hydrorefining zone and the high-temperature hydrorefining zone can be the same or different.

[0013] Furthermore, the reaction conditions of the cracking reactor are as follows: reaction pressure of 4.0~10.0 MPa, preferably 5.0~8.0 MPa; hydrogen-to-oil volume ratio of 300:1~600:1, preferably 400:1~500:1; and liquid hourly space velocity of 0.25~3.0 h⁻¹. -1 Preferably 0.5~2.0h -1 The reaction temperature is 350~450℃, preferably 380~420℃.

[0014] Furthermore, the hydrogenation ring-opening zone completes the cycloalkane ring-opening reaction of tetrahydronaphthalene-based indenhydride molecules; the dealkylation reaction zone completes the dealkylation reaction of long-chain alkylbenzenes; and the alkyl transfer reaction zone completes the conversion of polymethylbenzenes, ultimately yielding the BTX product. The volume ratio of the hydrogenation ring-opening zone, the dealkylation reaction zone, and the alkyl transfer reaction zone is (4~6):(2~3):(2~3).

[0015] Furthermore, the hydrogenation ring-opening reaction zone can be filled with a commercially available hydrocracking catalyst, such as FC-70A developed by the Dalian Petrochemical Research Institute.

[0016] Further, the dealkylation reaction zone is packed with a dealkylation catalyst whose main component is ZSM-5 molecular sieve (preferably modified ZSM-5 molecular sieve). The dealkylation catalyst contains modified ZSM-5 molecular sieve, a binder, and a hydrogenating metal. Based on the weight of the dealkylation catalyst, it contains 50wt%~90wt% modified ZSM-5 molecular sieve and 2.0~15.0wt%, preferably 5.0~10.0wt%, of the hydrogenating metal (as oxide). The total acidity of the dealkylation catalyst is 0.05~0.12mmol / g, the acidity outside the pores is not higher than 5.0μmol / g, preferably 1.0~3.0μmol / g, and the pore volume is 0.18~0.30cm³. 3 / g, wherein the micropore volume is 0.03~0.09cm³. 3 / g,

[0017] Further, the alkyl transfer reaction zone is filled with an alkyl transfer catalyst whose main component is Beta molecular sieve (preferably modified Beta molecular sieve). The alkyl transfer catalyst contains modified Beta molecular sieve, a binder, and a hydrogenation metal, and based on the weight of the alkyl transfer catalyst, contains 20wt%~60wt% modified Beta molecular sieve, 2.0~15.0wt%, preferably 5.0~10.0wt% hydrogenation metal (calculated as oxides). The total acidity of the alkyl transfer catalyst is 0.25~0.45 mmol / g, the acidity outside the pores is not higher than 10.0 μmol / g, preferably 3.0~7.0 μmol / g, and the pore volume is 0.30~0.45 cm³. 3 / g, wherein the micropore volume is 0.15~0.30cm³. 3 / g.

[0018] Furthermore, the hydrogenated metal is a metal of Group VIB and / or Group VIII, wherein the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0019] Compared with the prior art, the method for producing BTX by LCO hydrocracking of the present invention has the following advantages:

[0020] (1) Based on the reaction process of LCO hydrocracking, this invention utilizes the characteristic that the saturated reaction of monocyclic aromatic hydrocarbons is most easily carried out at 350℃~370℃, and sets up a low-temperature denitrification zone and a high-temperature aromatics preservation zone in the refining reactor to achieve deep denitrification while reducing aromatic hydrocarbon loss.

[0021] (2) By taking advantage of the different requirements of the catalyst materials required for hydrogenation ring-opening reaction, dealkylation reaction and alkyl transfer reaction in terms of pore size, acidity and other properties, the hydrogenation ring-opening zone, dealkylation reaction zone and alkyl transfer reaction zone are designed, and the appropriate catalysts are used to guide the reactant molecules to the optimal reaction path, thereby improving the yield of BTX.

[0022] (3) By utilizing the microporous channel characteristics of molecular sieves, acid centers on the outer surface of molecular sieves are selectively removed, avoiding the adsorption and condensation of larger molecules on the mesopores and outer surface, reducing carbon buildup, and improving the service life of the catalyst. Implementation

[0023] In this embodiment of the invention, the preparation of the modified ZSM-5 molecular sieve or the modified Beta molecular sieve includes the following steps:

[0024] (1) Perform hydrothermal treatment on ZSM-5 molecular sieve or Beta molecular sieve raw powder;

[0025] (2) Impregnate the material obtained in step (1) with a channel protection liquid;

[0026] (3) The material obtained in step (2) is treated with a sterically hindered organic acid;

[0027] (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment;

[0028] (5) The material obtained in step (4) is filtered, washed, dried and calcined to obtain modified molecular sieve.

[0029] Further, in step (1), the ZSM-5 molecular sieve can be a commercially available product or a microporous hydrogen-type ZSM-5 molecular sieve prepared according to existing technology. The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 30~100.

[0030] Furthermore, in step (1), the Beta molecular sieve can be a commercially available product or a microporous hydrogen-type Beta molecular sieve prepared according to existing technology. The properties of the Beta molecular sieve are as follows: SiO2 / Al2O3 molar ratio 20~40.

[0031] Furthermore, in step (1), the specific treatment process in the hydrothermal process is as follows: A commercially available molecular sieve is placed in a hydrothermal furnace, steam is introduced, and the process is carried out for 1 to 3 hours at a temperature of 400℃ to 600℃ and a pressure of 0.05 to 0.2 MPa.

[0032] Further, in step (2), the pore protection solution is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, tetrapropylammonium hydroxide solution, etc. The concentration of the pore protection solution is 0.8~2.0 mol / L, preferably 1.1~1.5 mol / L.

[0033] Furthermore, in step (2), the impregnation is preferably an equal-volume impregnation. The impregnation treatment temperature is room temperature, generally 20~25℃.

[0034] Further, in step (3), the sterically hindered organic acid is one or more of 2,4-dimethylbenzenesulfonic acid and 2,5-dimethylbenzoic acid.

[0035] Further, in step (3), the specific operation is as follows: first, the material obtained in step (2) is mixed with water, wherein the liquid-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1, and then organic acid is added until the pH value of the solution drops below 8, preferably 6.5 to 7.5.

[0036] Further, in step (4), the dealuminizing and silicon-replenishing reagent is at least one of ammonium hexafluorosilicate solution, tetraethyl orthosilicate solution, etc. The molar concentration of the dealuminizing and silicon-replenishing reagent is 0.3~1.0 mol / L. The mass ratio of the material obtained in step (4) to the dealuminizing and silicon-replenishing reagent is 1:1~1:5. The mixing temperature is 60~100℃.

[0037] Further, the specific operation process of step (4) is as follows: rapidly heat the material obtained in step (3) to 60~100℃ and continuously stir, add the aluminum removal and silicon replenishment reagent dropwise, and continue stirring for 60~120min after the dropwise addition is completed. Among them, the dropwise addition rate does not exceed 0.5mL / min·g of the material obtained in step (3); preferably 0.2~0.4mL / min·g of the material obtained in step (3).

[0038] Furthermore, in step (5), the filtration and washing can be carried out using conventional methods in the art, the drying temperature is 100℃~150℃, the drying time is 2~4h, the calcination temperature is 400℃~600℃, and the calcination time is 3~5h.

[0039] In this embodiment of the invention, the preparation of the dealkylation catalyst or alkyl transfer catalyst includes the preparation of a catalyst support and a hydrogenation metal loading process: the catalyst support is prepared by mixing, extruding, and molding modified molecular sieves and aluminum sol binder, followed by drying and calcination to obtain the catalyst support; the hydrogenation metal loading process adopts the impregnation method.

[0040] The following examples and comparative examples further illustrate the role and effect of the technical solution of the present invention, but the following examples do not constitute a limitation on the scope of protection of the present invention.

[0041] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0042] In this invention, the total acid content is determined as follows: The powdered catalyst is compressed into tablets, evacuated, and then degassed at 450°C for 2 hours. After the temperature drops to room temperature, a pyridine molecule with a kinetic diameter of 5 Å is used as a probe molecule to measure the infrared spectrum of chemical desorption, and the adsorption amount is calculated. Since the diameter of the pyridine molecule is smaller than that of the molecular sieve pores, this method can yield the total acid content.

[0043] In this invention, the method for determining the amount of acid outside the micropores is as follows: The powdered catalyst is compressed into tablets, evacuated, and then degassed at 450°C for 2 hours. After the temperature drops to room temperature, 2,6-di-tert-butylpyridine molecules are used as probe molecules to measure the infrared spectrum of its chemical desorption, and the adsorption amount is calculated. Since the diameter of 2,6-di-tert-butylpyridine molecules is larger than that of the molecular sieve pores, this method can obtain the amount of acid outside the micropores.

[0044] In this invention, pore volume and micropore volume are determined by physical adsorption: an ASAP 2420 cryogenic liquid nitrogen physical adsorption instrument manufactured by Micrometics, USA, is used. Before measurement, the sample is first calcined at 550℃ for 4 hours to remove the template agent. During testing, the sample is pretreated at 300℃ for 3 hours, and then nitrogen is adsorbed at 77K for testing.

[0045] The formula for calculating BTX yield in this embodiment is as follows:

[0046] BTX yield = (total mass of BTX in product / mass of raw material) * 100%.

[0047] Both the examples and comparative examples used LCO from a certain refinery as raw material, and its composition is shown in Table 1.

[0048] Table 1 LCO Raw Materials

[0049]

[0050] Example 1

[0051] The dealkylation catalyst CAT-1 containing modified ZSM-5 molecular sieve was prepared according to the method of this patent. Its properties are as follows: total acidity is 0.10 mmol / g, external acidity is 2.6 μmol / g, and pore volume is 0.28 cm³. 3 / g, of which the micropore volume is 0.09cm³ 3 / g, NiO content (as oxide) is 2.0wt%, WO3 content (as oxide) is 8.0wt%.

[0052] An alkyl transfer catalyst CAT-2 containing modified Beta molecular sieves was prepared according to the method described in this patent. Its properties are as follows: total acidity is 0.43 mmol / g, external acidity is 3.8 μmol / g, and pore volume is 0.42 cm³. 3 / g, of which the micropore volume is 0.28cm³ 3 / g, NiO content (as oxide) is 2.0wt%, WO3 content (as oxide) is 8.0wt%.

[0053] The dealkylation catalyst CAT-3 containing modified ZSM-5 molecular sieve was prepared according to the method of this patent. Its properties are as follows: total acidity is 0.05 mmol / g, external acidity is 0.8 μmol / g, and pore volume is 0.20 cm³. 3 / g, of which the micropore volume is 0.04cm³ 3 / g, NiO content (as oxide) is 1.0wt%, WO3 content (as oxide) is 4.0wt%.

[0054] An alkyl transfer catalyst CAT-4 containing modified Beta molecular sieves was prepared according to the method of this patent. Its properties are as follows: total acidity is 0.27 mmol / g, external acidity is 3.1 μmol / g, and pore volume is 0.32 cm³. 3 / g, of which the micropore volume is 0.18cm³ 3 / g, NiO content (as oxide) is 1.0wt%, WO3 content (as oxide) is 4.0wt%.

[0055] Example 1-1

[0056] CAT-1B was prepared using commercial ZSM-5 molecular sieve as a raw material. Its properties are as follows: total acidity 0.27 mmol / g, external acidity 0.015 mmol / g, and pore volume 0.39 cm³. 3 / g, of which the micropore volume is 0.11cm³ 3 / g, NiO content (as oxide) is 2.0wt%, WO3 content (as oxide) is 8.6wt%.

[0057] CAT-2B was prepared using commercial Beta molecular sieves as raw material. Its properties are as follows: total acidity 0.54 mmol / g, external acidity 0.024 mmol / g, and pore volume 0.45 cm³. 3 / g, of which the micropore volume is 0.30cm³ 3 / g, NiO content (as oxide) is 2.1wt%, WO3 content (as oxide) is 8.4wt%.

[0058] Example 2

[0059] The hydrorefining reactor, hydroring-opening zone, dealkylation reaction zone, and alkyl transfer reaction zone were respectively filled with FF-66, FC-70A, CAT1, and CAT2. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 2. The fraction with a temperature of 145–210 °C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature above 210 °C was circulated to the inlet of the hydrosaturated reaction zone. The reactor was operated for 168 h. The BTX yield was 33.3 wt%, and the catalyst carbon deposition was 1.4%.

[0060] Table 2 Conditions of each reaction zone in Example 2

[0061]

[0062] Comparative Example 2

[0063] Neither the hydrorefining reactor nor the hydrocracking reactor was divided into reaction zones. Both were charged with FF-66 and FC-70A catalysts, respectively. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 3. The fraction above 145°C was circulated to the inlet of the hydrosaturated reaction zone and operated for 168 hours. The BTX yield was 24.6 wt%, and the catalyst carbon deposition was 2.5%.

[0064] Table 3 Conditions of each reaction zone in Comparative Example 2

[0065]

[0066] Example 3

[0067] The hydrorefining reactor, hydroring-opening zone, dealkylation reaction zone, and alkyl transfer reaction zone were respectively filled with FF-66, FC-70A, CAT1B, and CAT2B. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 4. The fraction with a temperature of 145–210 °C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature above 210 °C was circulated to the inlet of the hydrosaturated reaction zone. The reactor was operated for 168 h. The BTX yield was 31.6 wt%, and the catalyst carbon deposition was 2.7%.

[0068] Table 4 Conditions of each reaction zone in Example 3

[0069]

[0070] Example 4

[0071] The hydrorefining reactor, hydroring-opening zone, dealkylation reaction zone, and alkyl transfer reaction zone were respectively filled with FF-66, FC-70A, CAT3, and CAT4. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 5. The fraction with a temperature of 145–210 °C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature above 210 °C was circulated to the inlet of the hydrosaturated reaction zone. The reactor was operated for 168 h. The BTX yield was 34.4 wt%, and the catalyst carbon deposition was 2.3%.

[0072] Table 5 Conditions of each reaction zone in Example 4

[0073]

[0074] Example 5

[0075] The hydrorefining reactor, hydroring-opening zone, dealkylation reaction zone, and alkyl transfer reaction zone were respectively filled with FF-66, FC-70A, CAT1, and CAT4. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 6. The fraction with a temperature of 145–210 °C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature above 210 °C was circulated to the inlet of the hydrosaturated reaction zone. The reactor was operated for 168 h. The BTX yield was 34.9 wt%, and the catalyst carbon deposition was 1.3%.

[0076] Table 6 Conditions of each reaction zone in Example 5

[0077]

[0078] Example 6

[0079] The hydrorefining reactor, hydroring-opening zone, dealkylation reaction zone, and alkyl transfer reaction zone were respectively filled with FF-66, FC-70A, CAT3, and CAT2. After catalyst sulfidation using jet fuel with a dimethyl disulfide content of 4%, the conditions for each reaction zone were set as shown in Table 7. The fraction with a temperature of 145–210 °C was circulated to the inlet of the dealkylation reaction zone, and the fraction with a temperature above 210 °C was circulated to the inlet of the hydrosaturated reaction zone. The reactor was operated for 168 h. The BTX yield was 35.3 wt%, and the catalyst carbon deposition was 1.5%.

[0080] Table 7 Conditions of each reaction zone in Example 6

[0081]

Claims

1. A method for producing BTX by LCO hydrocracking, characterized in that: The method includes the reaction stream LCO being fed sequentially into a hydrorefining reactor and a hydrocracking reactor. The hydrorefining reactor is provided with a low-temperature hydrorefining zone and a high-temperature hydrorefining zone along the stream direction. The hydrocracking reactor is provided with a hydroring-opening zone, a dealkylation reaction zone and an alkyl transfer reaction zone along the stream direction. The reacted material is separated to obtain BTX. The volume ratio of the low-temperature hydrogenation refining zone to the high-temperature hydrogenation refining zone is 3:7 to 7:

3. The reaction temperature of the low-temperature hydrogenation refining zone is 300 to 350°C, and the reaction temperature of the high-temperature hydrogenation refining zone is 370 to 420°C. The volume ratio of the hydrogenation ring-opening zone, the dealkylation reaction zone, and the alkyl transfer reaction zone is (4~6):(2~3):(2~3); The dealkylation reaction zone is filled with a dealkylation catalyst whose main component is modified ZSM-5 molecular sieve. The total acidity of the dealkylation catalyst is 0.05~0.12 mmol / g, the acidity outside the pores is not higher than 5.0 μmol / g, and the pore volume is 0.18~0.30 cm³. 3 / g, wherein the micropore volume is 0.03~0.09cm³. 3 / g; The alkyl transfer reaction zone is filled with an alkyl transfer catalyst whose main component is modified Beta molecular sieve. The total acidity of the alkyl transfer catalyst is 0.25~0.45 mmol / g, the acidity outside the pores is not higher than 10.0 μmol / g, and the pore volume is 0.30~0.45 cm³. 3 / g, wherein the micropore volume is 0.15~0.30cm³. 3 / g.

2. The method according to claim 1, characterized in that: The properties of the LCO are as follows: density is 0.85~1.00 kg / cm³. 3 The sulfur content is 30ppm~20000ppm, and the nitrogen content is 30ppm~1000ppm.

3. The method according to claim 1, characterized in that: The reaction conditions of the hydrorefining reactor are as follows: The reaction pressure was 4.0–10.0 MPa; the hydrogen-to-oil volume ratio was 300:1–600:1; and the liquid hourly space velocity (LHSV) was 0.25–3.0 h⁻¹. -1 .

4. The method according to claim 1, characterized in that: The reaction conditions of the hydrorefining reactor are as follows: The reaction pressure is 5.0~8.0 MPa, the hydrogen-to-oil volume ratio is 400:1~500:1, and the liquid hourly space velocity is 0.5~2.0 h⁻¹. -1 .

5. The method according to claim 1, characterized in that: The low-temperature hydrorefining zone completes hydrodenitrification, hydrodesulfurization, and hydrogen saturation of polycyclic aromatic hydrocarbons to obtain monocyclic aromatic hydrocarbons; the high-temperature hydrorefining zone completes deep denitrification.

6. The method according to claim 1, characterized in that: The low-temperature hydrogenation refining zone has a reaction temperature of 320~340℃; the high-temperature hydrogenation refining zone has a reaction temperature of 390~410℃.

7. The method according to claim 1, characterized in that: The catalysts packed in the low-temperature hydrorefining zone and the high-temperature hydrorefining zone may be the same or different.

8. The method according to claim 1, characterized in that: The reaction conditions of the hydrocracking reactor are as follows: reaction pressure 4.0~10.0 MPa; hydrogen-to-oil volume ratio 300:1~600:1; liquid hourly space velocity 0.25~3.0 h⁻¹. -1 The reaction temperature is 350~450℃.

9. The method according to claim 1, characterized in that: The reaction conditions of the hydrocracking reactor are as follows: reaction pressure 5.0~8.0 MPa, hydrogen-to-oil volume ratio 400:1~500:1, and liquid hourly space velocity 0.5~2.0 h⁻¹. -1 The reaction temperature is 380~420℃.

10. The method according to claim 1, characterized in that: The hydrogenation ring-opening zone completes the cycloalkane ring-opening reaction of tetrahydronaphthalene and indane molecules; the dealkylation reaction zone completes the dealkylation reaction of long side-chain alkylbenzenes; and the alkyl transfer reaction zone completes the conversion of polymethylbenzenes, ultimately yielding the BTX product.

11. The method according to claim 1, characterized in that: The dealkylation catalyst contains modified ZSM-5 molecular sieve, binder, and hydrogenated metal. Based on the weight of the dealkylation catalyst, it contains 50wt%~90wt% modified ZSM-5 molecular sieve and 2.0~15.0wt% hydrogenated metal as oxides. The acid content outside the pores of the dealkylation catalyst is 1.0~3.0μmol / g.

12. The method according to claim 11, characterized in that: Based on the weight of the dealkylation catalyst, it contains 5.0 to 10.0 wt% of hydrogenation metals as oxides.

13. The method according to claim 1, characterized in that: The alkyl transfer catalyst contains modified Beta molecular sieve, binder, and hydrogenated metal. Based on the weight of the alkyl transfer catalyst, it contains 20wt%~60wt% modified Beta molecular sieve and 2.0~15.0wt% hydrogenated metal as oxides. The acid content outside the pores of the alkyl transfer catalyst is 3.0~7.0μmol / g.

14. The method according to claim 13, characterized in that: Based on the weight of the alkyl transfer catalyst, it contains 5.0 to 10.0 wt% of hydrogenated metals as oxides.

15. The method according to any one of claims 11-14, characterized in that: The hydrogenated metal is a metal from Group VIB and / or Group VIII.

16. The method according to claim 15, characterized in that: The Group VIB metal is molybdenum and / or tungsten.

17. The method according to claim 15, characterized in that: The metals in Group VIII are cobalt and / or nickel.

Images