Hydrocracking method for producing olefin material from light oil

Abstract

The invention relates to the field of conversion and utilization of hydrocarbon oil, and discloses a hydrocracking method for producing an olefin material from light oil. Raw oil I and raw oil II are respectively introduced into the hydrocracking reactor I filled with a hydrocracking catalyst I and the hydrocracking reactor II filled with a hydrocracking catalyst II for hydrocracking reaction, and a hydrocracking product I and a hydrocracking product II are respectively obtained; and separating the hydrocracking product I and the hydrocracking product II to obtain a C3 / C4 product and a light naphtha product of C5 and above. The method provided by the invention can be used for converting light oil (such as naphtha fraction) with lower additional value into a raw material suitable for being used as an olefin material product under a low-pressure hydrogen condition.

Description

Technical Field

[0001] The invention relates to the field of hydrocarbon oil conversion and utilization, and in particular to a hydrocracking method for producing olefin materials from light oil. Background Art

[0002] The sustained development of the national economy has brought about a sustained increase in the demand for chemical products, and along with it the demand for chemical raw materials.

[0003] At present, the production capacity of China's propane dehydrogenation units has reached 9.9 million tons / year, and the production capacity of ethylene units has reached nearly 42 million tons / year. The commissioning of newly built ethylene and propane dehydrogenation units in recent years has also brought about a rapid increase in the demand for chemical light oil and imported propane and butane. my country's current dependence on imported propane and butane is as high as 70%, and there is a very broad market for the production of this type of raw materials.

[0004] In addition, with the impact of new energy sources such as electricity, solar energy and hydrogen energy, the demand for fuel oil has gradually peaked, the demand for gasoline blending has declined, and the light oil of refineries represented by straight-run naphtha, reforming raffinate and coking naphtha has become oversupplied. In particular, products such as C5, C6 light hydrocarbons and light naphtha are generally difficult to use due to their low aromatic potential and octane number. Therefore, converting these low-value-added naphtha fractions into high-quality chemical light hydrocarbons through hydrocracking is of great significance to increasing the added value of oil products.

[0005] CN106062148A discloses a process for converting hydrocarbons into olefins, wherein a hydrocarbon raw material represented by naphtha is separated into multiple streams classified by carbon number through a hydrocracking unit, and the appropriate streams are fed to subsequent steam cracking, propane dehydrogenation and butane dehydrogenation units to produce olefins. The conditions of the hydrocracking unit in the method include a temperature of 470-550°C, a pressure of 0.6-3.0 MPa gauge pressure and a temperature of 0.2-10 h -1 Mass airspeed.

[0006] CN12409121A discloses a method for converting light naphtha into low-carbon olefins and aromatics, wherein light naphtha with a C5 and C6 paraffin content of 99% is separated by normal isomerization, and the isomer components are fed to a hydrocracking unit and separated to obtain refinery dry gas, propane, normal butane and isobutane, and then these components are further converted into ethylene and propylene by steam cracking or propane dehydrogenation. The conditions of the hydrocracking unit in the method include a temperature of 330 to 360°C and a pressure of 6 to 8 MPa gauge pressure. After separation by the hydrocracking unit, the proportions of refinery dry gas, propane, normal butane and isobutane are 6%, 31%, 29% and 34% respectively.

[0007] WO2019162392A1 discloses a method for converting the paraffins and cycloalkanes of naphtha raw materials into propane by hydrocracking. The naphtha raw materials without olefins are mixed with hydrogen and heated at a temperature of 200 to 600°C, a pressure of 1 to 10 MPa, and a feed mass space velocity of 0.1 to 10.0 h / min. -1 The hydrocracking reaction is carried out on a bifunctional catalyst under the condition of a hydrogen-to-oil molar ratio of 1 to 1000, and the catalyst used contains one or more of ZSM, MEL or SAPO type molecular sieves with acidic 10-membered ring channels.

[0008] CN113736516A discloses a process for treating naphtha to produce ethylene raw materials, wherein the naphtha fraction is mixed with hydrogen and then enters a liquid phase hydrogenation reactor, and the products after the hydrogenation reaction are separated by a fractionation tower, and the gas separated at the top of the tower is used as fuel gas, and qualified naphtha is obtained at the bottom of the tower as ethylene raw material. The method is a process for hydrogenation and refining of naphtha, wherein the reaction pressure in the liquid phase hydrogenation reactor is 2.0-6.0 MPa, the reaction temperature is 70-200°C, the liquid volume space velocity is 1-6 / hour, and the chemical hydrogen consumption is 0.2-1.0 weight %.

[0009] At present, the technical reaction conditions for producing ethylene raw materials from low-value-added naphtha are generally harsh, such as the pressure of more than 8MPa and the temperature of more than 400℃. Secondly, the yield of ideal light hydrocarbons such as propane, n-butane and n-pentane obtained under relatively mild conditions is low. Summary of the invention

[0010] The purpose of the present invention is to convert low value-added light oil (such as naphtha fraction) into high quality light hydrocarbons suitable as feedstock for olefin unit under low pressure hydrogenation conditions.

[0011] In order to achieve the above object, the present invention provides a hydrocracking method for producing olefin materials from light oil, which is carried out in a system containing a hydrocracking reactor I and a hydrocracking reactor II arranged in parallel, comprising:

[0012] (1) under low-pressure hydrogenation conditions, introducing the feedstock oil I and feedstock oil II into the hydrocracking reactor I filled with the hydrocracking catalyst I and the hydrocracking reactor II filled with the hydrocracking catalyst II, respectively, to carry out a hydrocracking reaction, thereby obtaining a hydrocracking product I and a hydrocracking product II, respectively;

[0013] (2) separating the hydrocracking product I and the hydrocracking product II to obtain a C3 / C4 product and a C5 and above light naphtha product;

[0014] The feedstock oil I and the feedstock oil II are each independently selected from at least one of light oils; the cycloalkane content in the feedstock oil I is 40wt%-100wt%, and the total saturated hydrocarbon content is ≮70wt%; the cycloalkane content in the feedstock oil II is 0wt%-40wt%, and the total saturated hydrocarbon content is ≮70wt%;

[0015] Controlling the conditions of the hydrocracking reaction so that the conversion rate I of the feedstock oil I is 38% to 95%, and the conversion rate II of the feedstock oil II is 42% to 96%;

[0016] The conversion rate I = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor I * yield of the liquid product of the hydrocracking product of the hydrocracking reactor I / mass percentage of C5 or higher hydrocarbons in the feedstock oil I) * 100%; the conversion rate II = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor II * yield of the liquid product of the hydrocracking product of the hydrocracking reactor II / mass percentage of C5 or higher hydrocarbons in the feedstock oil II) * 100%;

[0017] The hydrocracking catalyst I is different from the hydrocracking catalyst II, and the hydrocracking catalyst II contains at least one of a ZSM molecular sieve and a modified product of a ZSM molecular sieve as an acidic component.

[0018] The method of the present invention can convert light oil with lower added value (such as naphtha fraction) into a raw material suitable for olefin product under low-pressure hydrogenation conditions, for example, it can produce propane, n-butane and a small amount of light naphtha rich in low-carbon hydrocarbons under low-pressure hydrogenation conditions.

[0019] The treatment method provided by the present invention can take into account the activity and stability of the hydrocracking catalyst, and convert low value-added light oil (such as naphtha) into a propane-rich gas product at a high conversion rate. Further, according to a preferred method, according to the different cycloalkane contents of the raw materials, the method of the present invention can be converted in different hydrocracking reaction zones respectively, so as to realize the high-value utilization of cycloalkanes and paraffins in the raw materials and convert them into propane and low-carbon paraffins. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a process flow chart of a preferred specific embodiment of the hydrocracking method for producing olefin materials from light oil.

[0021] Description of Reference Numerals

[0022] 1, 3, 5, 7, 9, 10, 13, 14, 15, 17, 19, 20, 22, 23, 24 are all pipelines

[0023] 2 and 6 are both raw oil pumps

[0024] 4 and 8 are heating furnaces

[0025] 11 and 12 are both cracking reaction zones

[0026] 16. High-pressure separator

[0027] 18. Gas purification unit

[0028] 21. Fractionation unit DETAILED DESCRIPTION

[0029] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0030] As mentioned above, the present invention provides a hydrocracking method for producing olefin feed from light oil, which is carried out in a system comprising a hydrocracking reactor I and a hydrocracking reactor II arranged in parallel, comprising:

[0031] (1) under low-pressure hydrogenation conditions, introducing the feedstock oil I and feedstock oil II into the hydrocracking reactor I filled with the hydrocracking catalyst I and the hydrocracking reactor II filled with the hydrocracking catalyst II, respectively, to carry out a hydrocracking reaction, thereby obtaining a hydrocracking product I and a hydrocracking product II, respectively;

[0032] (2) separating the hydrocracking product I and the hydrocracking product II to obtain a C3 / C4 product and a C5 and above light naphtha product;

[0033] The feedstock oil I and the feedstock oil II are each independently selected from at least one of light oils; the cycloalkane content in the feedstock oil I is 40wt%-100wt%, and the total saturated hydrocarbon content is ≮70wt%; the cycloalkane content in the feedstock oil II is 0wt%-40wt%, and the total saturated hydrocarbon content is ≮70wt%;

[0034] Controlling the conditions of the hydrocracking reaction so that the conversion rate I of the feedstock oil I is 38% to 95%, and the conversion rate II of the feedstock oil II is 42% to 96%;

[0035] The conversion rate I = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor I * yield of the liquid product of the hydrocracking product of the hydrocracking reactor I / mass percentage of C5 or higher hydrocarbons in the feedstock oil I) * 100%; the conversion rate II = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor II * yield of the liquid product of the hydrocracking product of the hydrocracking reactor II / mass percentage of C5 or higher hydrocarbons in the feedstock oil II) * 100%;

[0036] The hydrocracking catalyst I is different from the hydrocracking catalyst II, and the hydrocracking catalyst II contains at least one of a ZSM molecular sieve and a modified product of a ZSM molecular sieve as an acidic component.

[0037] The method of the present invention may further include preheating the feedstock oils before subjecting the feedstock oils I and II to the hydrocracking reaction. The present invention has no particular requirements for the specific operation method for preheating, and it can be performed in a manner known in the art. There are no particular requirements for the target temperature of preheating, and for example, it can be equal to or slightly lower than the temperature of the subsequent hydrocracking reaction.

[0038] The present invention has no special requirements for the specific operation of separation. Those skilled in the art can use methods known in the art to separate the hydrocracking product I and the hydrocracking product II separately, or combine the hydrocracking product I and the hydrocracking product II for separation. Exemplarily, after the hydrocracking product I and the hydrocracking product II are mixed, gas-liquid separation is first performed (for example, in a gas-liquid separator), the gas phase can be returned to the reactor as circulating hydrogen for reuse, and the liquid phase product can enter the fractionation system for fractionation.

[0039] Preferably, the light oil contains no more than 30 wt% of C5-C7 normal hydrocarbons.

[0040] Preferably, the carbon number of the light oil is C5 to C12, and the content of saturated hydrocarbons is 70 wt% to 90 wt%.

[0041] Preferably, the dry point of the light oil is not higher than 200° C., the paraffin content is 30 wt % to 100 wt %, and the aromatic content is 0 wt % to 30 wt %.

[0042] Preferably, the cycloalkane content in the feedstock oil II is 0.1 wt% to 30 wt%.

[0043] According to a preferred specific implementation, the paraffin content in the feed oil I is 30wt% to 60wt%, and the cycloalkane content is 40wt% to 70wt%; the paraffin content in the feed oil II is ≮80wt%, and the cycloalkane content is ≯20wt%.

[0044] More preferably, the content of paraffins in the feedstock oil I is 40 wt% to 55 wt%, and the content of cycloparaffins is 45 wt% to 55 wt%.

[0045] Preferably, the light oil is selected from the group consisting of hydrocracking naphtha, ethylene raffinate, reforming raffinate, and DCC gasoline hydrogenation unit raffinate.

[0046] According to a particularly preferred embodiment, the nitrogen content in the light oil is ≯20 μg / g.

[0047] Preferably, the conditions of the hydrocracking reaction are independently satisfied: temperature is 280-420°C, pressure is 0.2-8.0 MPa, volume space velocity is 0.1-20.0 h -1 , the volume ratio of hydrogen to oil is 100~2000.

[0048] According to a preferred embodiment, the conditions of the hydrocracking reaction in the hydrocracking reactor I are as follows: temperature is 330-420°C, pressure is 1.0-8.0 MPa, volume space velocity is 2.0-16.0 h -1 , the volume ratio of hydrogen to oil is 500~2000.

[0049] According to another preferred embodiment, the conditions of the hydrocracking reaction in the hydrocracking reactor II meet the following conditions: temperature of 280-380°C, pressure of 0.1-6.4 MPa, volume space velocity of 0.5-16.0 h -1 , the volume ratio of hydrogen to oil is 300-1000.

[0050] Preferably, the hydrocracking catalyst I and the hydrocracking catalyst II both contain active metal components and carriers, and the carriers both contain acidic components; in the hydrocracking catalyst I and the hydrocracking catalyst II, the content of the active metal components in terms of oxide is independently 10 wt% to 50 wt%.

[0051] Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, the active metal elements in the active metal component are selected from at least two of Group VIB metal elements and Group VIII metal elements.

[0052] Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, the active metal element includes at least one selected from the metal elements of Group VIB and at least one selected from the metal elements of Group VIII.

[0053] More preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, based on the total weight of the hydrocracking catalyst, the content of the VIB group metal element is independently 5wt% to 35wt%, and the content of the VIII group metal element is independently 1wt% to 8wt% in terms of oxide.

[0054] According to a preferred specific embodiment, in the hydrocracking catalyst I and the hydrocracking catalyst II, the content of the acidic component is independently 45 wt% to 80 wt% based on the total weight of the carrier.

[0055] Preferably, in the hydrocracking catalyst I, the acidic component is at least one of a β-type molecular sieve, a modified product of a β-type molecular sieve, a Y-type molecular sieve, and a modified product of a Y-type molecular sieve.

[0056] Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, the carrier further contains a heat-resistant inorganic oxide, and the heat-resistant inorganic oxide is silicon oxide and / or aluminum oxide.

[0057] Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, the content of the heat-resistant inorganic oxide is independently 20 wt% to 55 wt% based on the weight of the carrier.

[0058] According to a preferred specific embodiment, based on the total volume of the catalysts in the hydrocracking reactor I and the hydrocracking reactor II, the filling volume of the hydrocracking catalyst I is 30% to 70%, and the filling volume of the hydrocracking catalyst II is 30% to 70%.

[0059] The present invention has no particular requirements on the source of the aforementioned catalyst, which can be prepared by methods known in the art, or a catalyst with corresponding characteristics can be purchased commercially. The present invention will not be described in detail herein, and those skilled in the art should not interpret this as a limitation of the present invention.

[0060] The following combination Figure 1 The process flow diagram shown provides a preferred specific embodiment of a hydrocracking method for producing olefin feed from light oil of the present invention. Specifically, the method comprises:

[0061] The raw oil I from pipeline 1 enters the heating furnace 4 through the raw oil pump 2 and pipeline 3, and is mixed with the new hydrogen from pipeline 24; the raw oil II from pipeline 5 enters the heating furnace 8 through the raw oil pump 6 and pipeline 7, and is mixed with the new hydrogen from pipeline 24. The raw oil I and the raw oil II are fed to the cracking reaction zone 11 and the cracking reaction zone 12 through pipeline 9 and pipeline 10 respectively, and mainly undergo hydrocracking reactions. The products obtained from the cracking reaction zone 11 and the cracking reaction zone 12 are respectively drawn out through pipelines 13 and 14 and mixed in pipeline 15 before entering high-pressure separator 16 for gas-liquid phase separation; the gas phase flowing out of the high-pressure separator enters gas purification unit 18 through pipeline 17, and the purified gas can be used as circulating hydrogen to return to the reactor through pipeline 19; the liquid phase flowing out of the high-pressure separator enters fractionation unit 21 through pipeline 20, and the propane-rich gas phase obtained in the fractionation unit exits the device through pipeline 22; after fractionation in the fractionation unit, light naphtha containing C5 and above components is drawn out from pipeline 23, and this part of light naphtha can also be used as unconverted oil according to production needs, mixed with raw oil from the pipeline through a pipeline, and then circulated to the reaction system for full conversion.

[0062] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials used are all common commercially available products.

[0063] Unless otherwise specified, the following examples use Figure 1 The process flow shown is carried out.

[0064] The properties of the light oil used below are listed in Table 1; the properties of the catalyst used are listed in Table 2.

[0065] The catalysts used in the following examples are prepared by methods known in the art, for example, by the method provided in CN112742440A.

[0066] Table 1: Properties of light oil

[0067] Crude oil Light oil A Light oil B Light oil C Light oil D <![CDATA[Density (20 °C) / (g / cm 3 )]]> 0.7106 0.6713 0.7249 0.7368 N mass fraction / (μg / g) 0.4 <0.3 0.3 11 S mass fraction / (μg / g) 0.3 1 0.3 161 Paraffin content, mass % 49.45 91.82 45.15 42.63 Olefins, mass% / / / 13.41 C8 and above cycloalkanes, mass % 11.58 1.25 22.83 5.63 Total cycloalkanes, mass % 49.73 7.44 34.4 6.67 Aromatics, mass% 0.71 0.27 20.45 37.29 Distillation range (ASTM-D86), ℃ IBP 59 61 69 35 10％ 64 65 80 48 50％ 78 72 112 103 90％ 117 98 162 174 FBP 147 122 177 199

[0068] Table 2: Catalyst conditions

[0069]

[0070] Example 1

[0071] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0072] The distribution and properties of the obtained products are listed in Table 4.

[0073] Example 2

[0074] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0075] The distribution and properties of the obtained products are listed in Table 4.

[0076] Example 3

[0077] use Figure 1 The process flow shown is for processing light oil A and light oil C, and the process parameters and other information involved are listed in Table 3.

[0078] The distribution and properties of the obtained products are listed in Table 4.

[0079] Example 4

[0080] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0081] The distribution and properties of the obtained products are listed in Table 4.

[0082] Comparative Example 1

[0083] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0084] The distribution and properties of the obtained products are listed in Table 4.

[0085] Comparative Example 2

[0086] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0087] The distribution and properties of the obtained products are listed in Table 4.

[0088] Comparative Example 3

[0089] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3.

[0090] The distribution and properties of the obtained products are listed in Table 4.

[0091] Comparative Example 4

[0092] use Figure 1 The process flow shown in the figure is carried out, and the process parameters and other information involved are listed in Table 3. The distribution and properties of the obtained products are listed in Table 4.

[0093] Table 3

[0094]

[0095] Table 3 (Continued)

[0096]

[0097] Table 4

[0098]

[0099]

[0100] It can be seen from the results in Table 4 that the method of the present invention for converting low value-added naphtha from a refinery into olefin materials has high propane selectivity while appropriately taking into account the effects of n-butane, C5 and C6.

[0101] In addition, from the results of Examples 3 and 4 above, it can be seen that using a hydrocracking catalyst within the preferred range to convert the target feedstock can obtain a similar product distribution, but the required reaction conditions are slightly different depending on the performance of the catalyst.

[0102] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A hydrocracking method for producing olefins from light oil, characterized in that: The method is carried out in a system comprising a hydrocracking reactor I and a hydrocracking reactor II arranged in parallel, comprising: (1) under low-pressure hydrogenation conditions, introducing the feedstock oil I and feedstock oil II into the hydrocracking reactor I filled with the hydrocracking catalyst I and the hydrocracking reactor II filled with the hydrocracking catalyst II, respectively, to carry out a hydrocracking reaction, thereby obtaining a hydrocracking product I and a hydrocracking product II, respectively; (2) separating the hydrocracking product I and the hydrocracking product II to obtain a C3 / C4 product and a C5 and above light naphtha product; The feedstock oil I and the feedstock oil II are each independently selected from at least one of light oils; the cycloalkane content in the feedstock oil I is 40wt%-100wt%, and the total saturated hydrocarbon content is ≮70wt%; the cycloalkane content in the feedstock oil II is 0wt%-40wt%, and the total saturated hydrocarbon content is ≮70wt%; Controlling the conditions of the hydrocracking reaction so that the conversion rate I of the feedstock oil I is 38% to 95%, and the conversion rate II of the feedstock oil II is 42% to 96%; The conversion rate I = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor I * yield of the liquid product of the hydrocracking product of the hydrocracking reactor I / mass percentage of C5 or higher hydrocarbons in the feedstock oil I) * 100%; the conversion rate II = (1-mass percentage of C5 or higher hydrocarbons in the liquid product of the hydrocracking product of the hydrocracking reactor II * yield of the liquid product of the hydrocracking product of the hydrocracking reactor II / mass percentage of C5 or higher hydrocarbons in the feedstock oil II) * 100%; The hydrocracking catalyst I is different from the hydrocracking catalyst II, and the hydrocracking catalyst II contains at least one of a ZSM molecular sieve and a modified product of a ZSM molecular sieve as an acidic component.

2. The hydrocracking method according to claim 1, wherein: The carbon number of the light oil is C5-C12, and the content of saturated hydrocarbons is 70wt%-90wt%.

3. The hydrocracking reaction according to claim 1 or 2, wherein: The dry point of the light oil is not higher than 200° C., the paraffin content is 30 wt % to 100 wt %, and the aromatic content is 0 wt % to 30 wt %.

4. The hydrocracking reaction according to claim 1 or 2, wherein: The content of paraffin in the feedstock oil I is 30wt% to 60wt%, and the content of cycloparaffin is 40wt% to 70wt%; the content of paraffin in the feedstock oil II is ≮80wt%, and the content of cycloparaffin is ≯20wt%.

5. The hydrocracking reaction according to any one of claims 1 to 4, wherein: The light oil is selected from the group consisting of hydrocracking naphtha, ethylene raffinate, reforming raffinate, and DCC gasoline hydrogenation unit raffinate.

6. The hydrocracking method according to any one of claims 1 to 5, wherein: The nitrogen content in the light oil is ≯20 μg / g.

7. The hydrocracking method according to any one of claims 1 to 6, wherein: The conditions of the hydrocracking reaction are independently satisfied; the temperature is 280-420°C, the pressure is 0.2-8.0 MPa, and the volume space velocity is 0.1-20.0 h -1 , the volume ratio of hydrogen to oil is 100~2000.

8. The hydrocracking method according to any one of claims 1 to 7, wherein: The conditions of the hydrocracking reaction in the hydrocracking reactor I are as follows: temperature of 330-420°C, pressure of 1.0-8.0 MPa, volume space velocity of 2.0-16.0 h -1 , the volume ratio of hydrogen to oil is 500-2000; Preferably, the conditions of the hydrocracking reaction in the hydrocracking reactor II meet the following requirements: temperature of 280-380°C, pressure of 0.1-6.4 MPa, volume space velocity of 0.5-16.0 h -1 , the volume ratio of hydrogen to oil is 300-1000.

9. The hydrocracking method according to any one of claims 1 to 8, wherein: The hydrocracking catalyst I and the hydrocracking catalyst II both contain active metal components and carriers, and the carriers both contain acidic components; in the hydrocracking catalyst I and the hydrocracking catalyst II, the content of the active metal components in terms of oxide is independently 10 wt% to 50 wt%; Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, the active metal element in the active metal component is selected from at least two of the metal elements of Group VIB and the metal elements of Group VIII; Preferably, the active metal element includes at least one selected from the metal elements of Group VIB and at least one selected from the metal elements of Group VIII; Preferably, in the hydrocracking catalyst I and the hydrocracking catalyst II, based on the total weight of the hydrocracking catalyst, the content of the VIB group metal element is independently 5wt% to 35wt%, and the content of the VIII group metal element is independently 1wt% to 8wt% in terms of oxide.

10. The hydrocracking method according to claim 9, wherein: In the hydrocracking catalyst I and the hydrocracking catalyst II, the content of the acidic component is independently 45 wt% to 80 wt% based on the total weight of the carrier.

11. The hydrocracking method according to claim 10, wherein: In the hydrocracking catalyst I, the acidic component is at least one of a β-type molecular sieve, a modified product of a β-type molecular sieve, a Y-type molecular sieve, and a modified product of a Y-type molecular sieve.

12. The hydrocracking method according to claim 9, wherein: The carriers also contain heat-resistant inorganic oxides, which are silicon oxide and / or aluminum oxide; Preferably, based on the weight of the carrier, the content of the heat-resistant inorganic oxide is 20 wt% to 55 wt%.

13. The hydrocracking method according to any one of claims 1 to 12, wherein: Based on the total volume of the catalysts in the hydrocracking reactor I and the hydrocracking reactor II, the loading volume of the hydrocracking catalyst I is 30% to 70%, and the loading volume of the hydrocracking catalyst II is 30% to 70%.

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