A method for hydrogenation conversion to produce high yields of chemical feedstocks

Abstract

This invention discloses a hydroconversion method for producing a large amount of chemical feedstock. The method includes the following steps: catalytic diesel fuel is sequentially passed through a hydrorefining reaction zone and a hydrocracking reaction zone 1, where it is contacted with a hydrorefining catalyst and a hydrocracking catalyst, respectively, to undergo hydrorefining and hydrocracking reactions. The hydrocracking residue is separated to obtain light naphtha, heavy naphtha, light diesel fuel, and heavy diesel fuel. The heavy naphtha is then subjected to aromatics extraction to obtain BTX. The light diesel fuel can be recycled back to the hydrocracking reaction zone 1 or enter a separately set hydrocracking reaction zone 2, while the heavy diesel fuel is recycled back to the hydrorefining reaction zone. This method can effectively increase the BTX yield of the hydroconversion unit while reducing aromatics loss during the hydrotreating process.

Description

Technical Field

[0001] This invention relates to a hydroconversion method for producing a large quantity of chemical feedstocks, specifically a hydroconversion method for producing a large quantity of chemical feedstock BTX using catalytic diesel as feedstock. Background Technology

[0002] Light aromatic hydrocarbons, such as benzene, toluene, and xylene, are important basic chemical raw materials. With industrial development and improved living standards, the synthetic fiber, synthetic plastics, and synthetic rubber industries have grown rapidly, leading to a year-on-year increase in demand for bicyclic aromatic hydrocarbons (BTX), resulting in a supply shortage. Hydrocracking is an ideal way to address the diesel surplus and low-carbon aromatic hydrocarbon shortage by converting bicyclic aromatic hydrocarbons in catalytic diesel into light aromatic hydrocarbons (such as BTX). During hydrocracking, bicyclic aromatic hydrocarbons first undergo partial hydrogenation to form tetrahydronaphthalene compounds, followed by ring-opening and side-chain breaking to generate short-chain BTX aromatic hydrocarbons.

[0003] CN201510761954.9 discloses a method for grading hydrocracking catalysts and a catalytic diesel hydroconversion process. The grading method includes the following steps: dividing the hydrocracking reactor into 2 to 8 equal reaction zones along the material flow direction; each reaction zone is loaded with a hydrocracking catalyst containing a regenerator; based on the weight of the hydrocracking catalyst, the regenerator content in the hydrocracking catalyst is 10wt% to 90wt%, with the regenerator content gradually increasing in each reaction zone along the material flow direction. This invention also provides a catalytic diesel hydroconversion process incorporating this hydrocracking catalyst grading method. By grading and loading catalysts with different reactivity within the cracking reactor, this invention improves the hydrogenation selectivity of diesel / gasoline components during the conversion process and increases the yield of high-octane gasoline products.

[0004] CN201711118958.0 discloses a method for producing high-quality gasoline and diesel from catalytic diesel, comprising the following steps: (1) high-aromatic catalytic diesel is mixed with circulating hydrogen and enters the I hydrorefining reaction zone for reaction; (2) the generated oil obtained in step (1) is mixed with circulating hydrogen and enters the II hydrorefining reaction zone for reaction, the reaction temperature being 30~120℃ higher than that of the I hydrorefining reaction zone; (3) the generated oil obtained in step (2) is cut into light components and heavy components; (4) the light components obtained in step (3) are mixed with circulating hydrogen and enter the hydrorefining reaction zone, the generated oil is separated to obtain gasoline fraction and diesel fraction; (5) the heavy components obtained in step (3) are mixed with circulating hydrogen and enter the hydroconversion reaction zone, the generated oil is separated by a separation system to obtain gas, gasoline and diesel fractions; (6) the gasoline obtained in step (4) is mixed with the gasoline obtained in step (5) to obtain qualified gasoline product, the diesel obtained in step (4) is mixed with the diesel obtained in step (5) to obtain qualified diesel product. This method can produce high-quality fuel oil products, and compared with other technologies, it has the advantages of low chemical hydrogen consumption and flexible product structure adjustment.

[0005] CN201711118979.2 discloses a method for catalytic diesel hydroconversion, comprising the following steps: (1) high-aromatic catalytic diesel is mixed with recycled hydrogen and enters the I hydrorefining reaction zone for reaction; (2) the product oil obtained in step (1) is mixed with recycled hydrogen and enters the II hydrorefining reaction zone for further reaction, the reaction temperature being 30~120℃ higher than that of the I hydrorefining reaction zone, and the liquid hourly space velocity being 0.2~1.5h-1 lower than that of the I hydrorefining reaction zone; (3) the product oil obtained in step (2) is mixed with recycled hydrogen and enters the hydrocracking reaction zone for hydrocarbon hydroconversion reaction; (4) the product oil obtained in step (3) is separated and fractionated by a separation and distillation system to obtain gas, light naphtha, heavy naphtha, and diesel fractions, with part of the diesel being recycled back to the II hydrorefining reaction zone and part of the diesel exiting the unit. The catalytic diesel hydroconversion method provided by this method can effectively increase the production of aromatics.

[0006] CN201811264072.1 This invention discloses a method for producing high-quality gasoline by catalytic diesel hydroconversion, comprising the following steps: (1) High-aromatic catalytic diesel is mixed with recycled hydrogen and enters a hydrorefining reaction zone for reaction, wherein the hydrorefining reaction zone is provided with at least two catalyst beds, and the sulfidation degree of the catalyst decreases along the flow direction; (2) The product oil obtained in step (1) enters a hydrocracking reaction zone and contacts at least two sulfidated hydrocracking catalysts to carry out a ring-opening conversion reaction of polycyclic aromatic hydrocarbons; (3) The product oil obtained in step (2) is separated by a separation system to obtain gas, gasoline, and diesel fractions. The method solves the problem of long initial adjustment period and low octane number of the main target product, gasoline fraction, during the production process.

[0007] CN201611045476.2 discloses a method for processing catalytic diesel fuel. The method involves separating the catalytic diesel feedstock into light and heavy components; the light components undergo hydrorefining and hydromodification reactions to obtain gasoline and diesel components; the heavy components undergo hydrorefining and hydroconversion to obtain gasoline and diesel components; the two gasoline and diesel components are mixed to obtain a gasoline product, and the two diesel components are mixed to obtain a diesel product. This invention, through a rational separation and processing procedure, allows for selective processing of different types of feedstocks, thereby enabling the efficient production of qualified gasoline and diesel products from inferior catalytic cracking diesel fuel.

[0008] CN201310540464.7 discloses a method for the hydroconversion of catalytic cracked diesel. Catalytic diesel is mixed with hydrogen and first fed into a hydrorefining reactor for hydrorefining. The effluent from the hydrorefining reaction directly enters a hydrocracking reactor, where it reacts with a graded catalyst bed. The hydrocracking reactor contains at least two cracking catalyst beds, and the hydrocracking catalyst activity decreases according to the flow direction of the reactants. The hydrocracking effluent is then separated and fractionated to obtain naphtha and diesel. This method can reduce excessive hydrogenation and secondary cracking of cracked naphtha while ensuring the effectiveness of diesel hydrocracking, thereby reducing chemical hydrogen consumption and improving the octane number and liquid yield of naphtha.

[0009] CN201811264066.6 discloses a method for catalytic diesel hydroconversion to maximize the production of aromatics, comprising the following steps: (1) high-aromatic catalytic diesel is mixed with recycled hydrogen and enters a hydrorefining reaction zone for reaction, wherein the hydrorefining reaction zone is provided with at least two catalyst beds, and the sulfidation degree of the catalyst decreases along the flow direction; (2) the product oil obtained in step (1) enters a hydrocracking reaction zone and contacts at least two sulfidation state hydrocracking catalysts to carry out a ring-opening conversion reaction of polycyclic aromatics; (3) the product oil obtained in step (2) is separated by a separation system to obtain gas, gasoline and diesel fractions, and all diesel fractions are recycled back to the hydrorefining reaction zone; (4) the naphtha obtained in step (3) enters an aromatics extraction unit and is extracted by solvent to obtain BTX product. This invention solves the problem of long initial adjustment cycle and low octane number of gasoline fraction, the main target product, in the application of the technology by using hydrorefining catalysts with different sulfidation degrees to balance the initial activity of the catalyst.

[0010] In existing technologies for the hydroconversion of catalytic diesel to produce more chemical feedstocks, a full-cycle operation mode of unconverted oil (i.e., diesel fraction produced by hydroconversion) is commonly adopted. This unconverted oil can be recycled to the inlet of the refining reactor or the inlet of the cracking reactor. Improving the yield of BTX products is one of the technical problems that engineers urgently need to solve. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a hydroconversion method for producing more chemical feedstocks. This method can effectively increase the BTX yield of the hydroconversion unit while reducing the loss of aromatics during the hydroconversion process.

[0012] A hydroconversion method for producing multiple chemical feedstocks includes the following steps: catalytic diesel fuel is sequentially passed through a hydrorefining reaction zone and a hydrocracking reaction zone 1, respectively, where it is contacted with a hydrorefining catalyst and a hydrocracking catalyst for hydrorefining and hydrocracking reactions. The hydrocracking material is separated to obtain light naphtha, heavy naphtha, light diesel fuel, and heavy diesel fuel. The heavy naphtha is then subjected to aromatics extraction to obtain BTX. The light diesel fuel can be recycled back to the hydrocracking reaction zone 1 or enter a separately set hydrocracking reaction zone 2, while the heavy diesel fuel is recycled back to the hydrorefining reaction zone.

[0013] In the method of this invention, the catalytic diesel oil generally has an initial boiling point of 60℃~220℃, preferably 170℃~210℃; and a density of generally 0.90 g / cm³. -3 ~0.99 g / cm -3 The nitrogen content is generally 0.03m%~0.2m%; the aromatic content is generally 50m%~90m%, preferably 65m%~85m%.

[0014] In the method of this invention, the hydrorefining catalyst includes a support and a hydrorefining active metal; wherein the support is an inorganic refractory oxide, generally selected from one or more of alumina, amorphous aluminum silicate, silica, or titanium dioxide; the hydrorefining active metal includes group VIB and / or group VIII metal components, wherein the group VIB metal is selected from tungsten and / or molybdenum, and its content in the catalyst is 5% to 30% by mass of oxide, preferably 10% to 20%; and the group VIII metal is selected from nickel and / or cobalt, and its content in the catalyst is 1% to 6% by mass of oxide, preferably 1.5% to 5%.

[0015] In the method of this invention, the reaction conditions in the hydrorefining reaction zone are generally: reaction pressure 3.0–15.0 MPa, preferably 5.0–12.0 MPa; liquid hourly space velocity (LISH) 0.1–15.0 h⁻¹. -1 Preferably 0.2–3.0 h -1 The average reaction temperature in the hydrogenation refining reaction zone is 300℃~450℃, preferably 350℃~400℃.

[0016] In the method of this invention, the hydrocracking catalyst typically comprises a cracking component, a hydrogenation component, and a binder. The catalyst can be a commercially available product or prepared according to existing techniques. The cracking component is a Y-type molecular sieve. The binder is typically alumina or silica. The hydrogenation active metal component is a Group VIB and / or Group VIII metal, such as one or more of Co, Ni, Mo, and W. The hydrogenation component content is typically 3–20 wt%, and the cracking component content is 30%–80 wt%, preferably 40%–70 wt%.

[0017] In the method of this invention, the hydrocracking reaction conditions are as follows: reaction pressure 3.0–15.0 MPa, preferably 5.0–12.0 MPa; liquid hourly space velocity (LHSV) 0.1–15.0 h⁻¹. -1 Preferably 0.2–3.0 h -1 The average reaction temperature in the hydrocracking reaction zone is 300℃~450℃, preferably 380℃~420℃.

[0018] In the method of the present invention, when the light diesel oil can be recycled back to the hydrocracking reaction zone 1, the final boiling point of the light diesel oil fraction is generally 240℃~320℃, preferably 260℃~300℃.

[0019] In the method of this invention, when the light diesel oil enters the separately configured hydrocracking reaction zone 2, the final boiling point of the light diesel oil fraction is generally 200℃~240℃, preferably 210℃~230℃. The reaction conditions are 1MPa~6MPa lower than the reaction pressure in the hydrocracking reaction zone 1, preferably 2MPa~4MPa, and the reaction temperature is 30℃~90℃ lower, preferably 40℃~80℃ lower. The cracking component in the hydrocracking catalyst packed in the hydrocracking reaction zone 2 can be a Y molecular sieve or a Beta molecular sieve, preferably a Beta molecular sieve.

[0020] In step (3) of the above method, the aromatic extraction can be carried out using existing technology. Conventional aromatic extraction methods mainly include liquid-liquid extraction or extractive distillation. This invention selects liquid-liquid extraction, and the extraction solvent is one or more of di(tri)ethylene glycol, tetraethylene glycol, sulfolane, N-methylpyrrolidone, and dimethyl sulfoxide. The extraction temperature is 20℃~200℃, preferably 50℃~150℃; the solvent: heavy naphtha mass ratio is 1:1~8:1, preferably 3:1~5:1; the pressure is 0MPa~2MPa, preferably 0.1~0.5MPa.

[0021] Through in-depth research, the inventors discovered that if the unconverted oil from catalytic diesel hydroconversion is recycled to the inlet of the refining reactor, some components, such as monocyclic aromatics, will be over-hydrogenated and saturated, resulting in the loss of aromatics. If the unconverted oil is recycled to the inlet of the cracking reactor, some components, such as certain bicyclic aromatics, will be difficult to achieve ring-opening cracking in the cracking reactor. At the same time, due to the influence of competitive adsorption, the cracking reaction of monocyclic aromatics will also be inhibited, affecting the yield of aromatics in the hydroconversion products. The method of this invention cuts the hydrocracking tail oil and processes it separately, effectively solving the above problems.

[0022] Compared with the prior art, the hydrogenation conversion method for producing more chemical raw materials according to the present invention has the following beneficial effects:

[0023] (1) Further separate the tail oil fraction obtained by catalytic diesel hydroconversion. Directly hydrocracking the light diesel with high monocyclic aromatic hydrocarbon enrichment prevents the loss of monocyclic aromatic hydrocarbons during the hydrorefining process. Polycyclic aromatic hydrocarbons are hydrosaturated to monocyclic aromatic hydrocarbons before cracking to prevent polycyclic aromatic hydrocarbons from directly cracking and occupying the acidic center of the cracking agent, and thus preventing the ring-opening cracking reaction from occurring.

[0024] (2) Light diesel contains a large amount of small molecule aromatics. These small molecule aromatics are recycled to the inlet of the cracking reaction zone. Due to their small molecular polarity, they are difficult to occupy acidic sites and undergo cracking reactions. Hydrocracking these small molecule aromatics separately can not only achieve effective conversion, but also reduce the loss of aromatics due to the milder operating conditions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the principle flow of a hydrogenation conversion method for producing multiple chemical raw materials, as used in an embodiment of the present invention.

[0026] 1 is catalytic diesel, 2 is hydrogen, 3 is the hydrorefining reaction zone, 4 is the hydrorefined product oil, 5 is the hydrocracking reaction zone, 6 is the hydrocracking product oil, 7 is the separator, 8 is the separated gas phase component, 9 is the separated liquid phase component, 10 is the fractionation tower, 11 is gas, 12 is light naphtha, 13 is heavy naphtha, 14 is light diesel, 15 is heavy diesel, 16 is the aromatics extraction zone, 17 is the BTX component, and 18 is the raffinate oil.

[0027] Figure 2 This is a schematic diagram of the principle flow of another hydrogenation conversion method for producing multiple chemical raw materials, adopted in an embodiment of the present invention.

[0028] 1 is catalytic diesel, 2 is hydrogen, 3 is hydrorefining reaction zone, 4 is hydrorefined product oil, 5 is hydrocracking reaction zone, 6 is hydrocracking product oil, 7 is separator, 8 is gas phase, 9 is liquid phase, 10 is fractionation tower, 11 is gas, 12 is light naphtha, 13 is heavy naphtha, 14 is light diesel, 15 is tail oil, 16 is aromatics extraction zone, 17 is BTX component, 18 is raffinate oil, 19 is low-pressure hydroconversion reaction zone, 20 is hydroconversion product oil, 21 is separator, 22 is gas phase, and 23 is liquid phase. Detailed Implementation

[0029] The following examples further illustrate the function and effect of the present invention, but the following examples do not constitute a limitation on the method of the present invention. Unless otherwise specified, all percentages in this application are mass percentages.

[0030] Figure 1 As shown, catalytic diesel 1 and hydrogen 2 are mixed and enter the hydrorefining reaction zone 3. The hydrorefined product 4 enters the hydrocracking reaction zone 5. The hydrocracking reaction zone product 6 enters the separator 7 to separate the gas phase 8, which is recycled. The liquid phase 9 enters the fractionation tower 10 to separate the gas 11, light naphtha 12, heavy naphtha 13, light diesel 14, and heavy diesel 15. The heavy naphtha 13 enters the aromatics extraction zone 16 to separate the BTX component 17 and raffinate 18. The light diesel 14 is recycled to the inlet of the hydrocracking reaction zone 5, and the heavy diesel 15 is recycled to the inlet of the hydrorefining reaction zone 3.

[0031] Figure 2 The process involves mixing catalytic diesel 1 with hydrogen 2 and entering the hydrorefining reaction zone 3. The hydrorefined product 4 enters the hydrocracking reaction zone 5. The hydrocracking product 6 enters the separator 7 to separate and obtain gas phase 8 for recycling. The liquid phase 9 enters the fractionation tower to separate and obtain gas 11, light naphtha 12, and heavy diesel 15. The heavy naphtha 13 enters the aromatics extraction zone 16 to separate and obtain BTX component 17 and raffinate 18. The light diesel 14 mixes with hydrogen 2 and enters the low-pressure hydrocracking reaction zone 19. The hydrocracking product 20 enters the separator 21 to separate and obtain gas phase 22 for recycling. Gas phase 23 enters the fractionation tower 10. The heavy diesel 15 is recycled to the inlet of the hydrorefining reaction zone 3.

[0032] In this embodiment of the invention, the hydrorefining catalyst used in the hydropretreatment reaction zone is FF-66, with a composition of 22 wt% MoO3, 5 wt% NiO, and the balance being alumina; the hydrocracking catalyst used in hydrocracking reaction zone 1 is FC-70A, with a composition of 12 wt% MoO3, 3 wt% NiO, 60 wt% Y-type molecular sieve, and the balance being alumina; both catalysts are manufactured by Sinopec Catalyst Co., Ltd. The hydrocracking catalyst used in hydrocracking reaction zone 2 is Cat-1, with a composition of 15 wt% MoO3, 5 wt% NiO, 50 wt% Beta-type molecular sieve, and the balance being alumina.

[0033] In the embodiments and comparative examples of the present invention, the process conditions using sulfolane as the extraction solvent are as follows: extraction temperature 80°C; solvent: heavy naphtha mass ratio of 4:1; pressure of 0.3 MPa.

[0034] The properties of catalytic diesel are shown in Table 1; the reaction conditions and results of the examples are shown in Table 2; and the reaction conditions and results of the comparative examples are shown in Table 3.

[0035] Table 1

[0036]

[0037] Table 2

[0038]

[0039] Comparative Example 1

[0040] Catalytic diesel first enters the hydrorefining reaction zone for hydrosaturation reaction. The hydrorefining reaction zone is filled with FF-66 hydrorefining catalyst. The hydrorefined product enters the hydrocracking reaction zone for hydrocracking reaction. The hydrocracking reaction zone is filled with FC-70A hydrocracking catalyst. The diesel fraction obtained by fractionation of the hydrocracking product is recycled to the inlet of the hydrocracking reaction zone.

[0041] Comparative Example 2

[0042] Catalytic diesel first enters the hydrorefining reaction zone for hydrosaturation reaction. The hydrorefining reaction zone is filled with FF-66 hydrorefining catalyst. The hydrorefined product enters the hydrocracking reaction zone for hydrocracking reaction. The hydrocracking reaction zone is filled with FC-70A hydrocracking catalyst. The diesel fraction obtained by fractionation of the hydrocracking product is recycled to the inlet of the hydrorefining reaction zone.

[0043] Table 3

[0044]

[0045] As can be seen from the above examples, the method of the present invention can effectively improve the BTX yield in catalytic diesel products.

Claims

1. A hydroconversion process for the production of chemical feedstocks, characterized in that: The method includes the following steps: catalytic diesel fuel is sequentially passed through a hydrorefining reaction zone and a hydrocracking reaction zone 1, where it is contacted with a hydrorefining catalyst and a hydrocracking catalyst respectively for hydrorefining and hydrocracking reactions. The hydrocracking residue is separated to obtain light naphtha, heavy naphtha, light diesel fuel, and heavy diesel fuel. The heavy naphtha is then subjected to aromatics extraction to obtain BTX. The light diesel fuel is recycled back to hydrocracking reaction zone 1 or enters a separately set hydrocracking reaction zone 2, while the heavy diesel fuel is recycled back to the hydrorefining reaction zone. The initial boiling point of the catalytic diesel fuel is 60℃~220℃, and its density is 0.90 g / cm³. 3 ~0.99 g / cm 3 The nitrogen content is 0.03m%~0.2m%, and the aromatic content is 50m%~90m%; when the light diesel is recycled back to the hydrocracking reaction zone 1, the final boiling point of the light diesel fraction is 240℃~320℃; when the light diesel enters the separately set hydrocracking reaction zone 2, the final boiling point of the light diesel fraction is 200℃~240℃.

2. The method of claim 1, wherein: The catalytic diesel has an initial boiling point of 170-210 DEG C and an aromatic hydrocarbon content of 65-85 m%.

3. The method of claim 1, wherein: The hydrofining catalyst comprises a carrier and a hydrogenation active metal; the carrier is selected from one or more of alumina, amorphous silica-alumina, silica or titania; the hydrogenation active metal comprises Group VIB and / or VIII metal components.

4. The method of claim 3, wherein: The Group VIB metal component in the hydrofining catalyst is selected from tungsten and / or molybdenum, and the content in the catalyst is 5-30% by mass of oxide; the Group VIII metal component is selected from nickel and / or cobalt, and the content in the catalyst is 1-6% by mass of oxide.

5. The method of claim 4, wherein: The Group VIB metal component in the hydrofining catalyst is selected from tungsten and / or molybdenum, and the content in the catalyst is 5-30% by mass of oxide; the Group VIII metal component is selected from nickel and / or cobalt, and the content in the catalyst is 1-6% by mass of oxide.

6. The method of claim 1, wherein: The reaction conditions of the hydrofining reaction zone are: reaction pressure 3.0-15.0 MPa; liquid hourly space velocity 0.1-15.0 h -1 ; average reaction temperature of the hydrofining reaction zone 300℃-450℃.

7. The method of claim 1, wherein: The reaction conditions of the hydrofining reaction zone are: reaction pressure 5.0-12.0 MPa; liquid hourly space velocity 0.2-3.0 h -1 The average reaction temperature of the hydrofining reaction zone is 350℃-400℃.

8. The method of claim 1, wherein: The Group VIB metal component in the hydrofining catalyst is selected from tungsten and / or molybdenum, and the content in the catalyst is 5-30% by mass of oxide; the Group VIII metal component is selected from nickel and / or cobalt, and the content in the catalyst is 1-6% by mass of oxide.

9. The method of claim 1, wherein: The reaction conditions of the hydrocracking zone are as follows: the reaction pressure is 3.0-15.0 MPa, the liquid hourly space velocity is 0.1-15.0 h -1 The average reaction temperature of the hydrocracking reaction zone is 300℃-450℃.

10. The method of claim 9, wherein: The reaction conditions of the hydrocracking zone are as follows: the reaction pressure is 5.0-12.0 MPa; the liquid hourly space velocity is 0.2-3.0 h -1 The average reaction temperature of the hydrocracking reaction zone is 380℃-420℃.

11. The method of claim 1, wherein: The hydrogenation component content in the hydrocracking catalyst is 3-20 wt%, and the cracking component content is 30-80 wt%.

12. The method of claim 1, wherein: The end boiling point of the light diesel fraction is 260-300 DEG C when the light diesel is recycled to the hydrocracking reaction zone 1.

13. The method of claim 9, wherein: The end boiling point of the light diesel fraction is 210-230 DEG C when the light diesel is introduced into the separately arranged hydrocracking reaction zone 2.

14. The method of claim 13, wherein: The reaction pressure of the hydrocracking reaction zone 2 is 1-6 MPa lower than that of the hydrocracking reaction zone 1, and the reaction temperature is 30-90 DEG C lower.

15. The method of claim 1, wherein: The reaction pressure of the hydrocracking reaction zone 2 is 2-4 MPa lower than that of the hydrocracking reaction zone 1, and the reaction temperature is 40-80 DEG C lower.

16. The method of claim 1, wherein: The cracking component in the hydrocracking catalyst loaded in the hydrocracking reaction zone 2 is Y molecular sieve or Beta molecular sieve. The cracking component in the hydrocracking catalyst loaded in the hydrocracking reaction zone 2 is Beta molecular sieve.

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