A hydrocracking process for producing propane from raffinate oil

Abstract

The present application relates to the field of light oil utilization conversion technology, and discloses a kind of hydrogenolysis method for producing propane from raffinate oil, which comprises: under low-pressure hydrogen condition, raffinate oil is sequentially introduced into hydrogenolysis reaction zone I filled with hydrogenolysis catalyst I and hydrogenolysis reaction zone II filled with hydrogenolysis catalyst II to carry out hydrogenolysis reaction, and hydrogenolysis product is obtained;The paraffin content in the raffinate oil is 48wt%-99wt%, and the total saturated hydrocarbon content is not less than 90wt%;The hydrogenolysis product is separated to obtain C3 / C4 product and light naphtha.The method provided by the present application can produce gas product mainly containing propane and n-butane under low-pressure hydrogen condition, and the raffinate oil fraction has lower added value and almost no aromatic hydrocarbon.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light oil conversion technology, and particularly relates to a hydrocracking method for producing propane from raffinate oil. BACKGROUND

[0002] The continuous development of the national economy brings about the continuous growth of the demand for chemical products, and the demand for chemical raw materials also increases.

[0003] At present, more than 50% of the raw materials of the ethylene cracking device in China are naphtha, but the triene yield of isomeric alkanes and naphthenes in naphtha is low, and the ideal raw material is n-alkane; the main raw material of the dehydrogenation device is propane, butane and the like, which currently depends on import to a great extent.

[0004] The raffinate oil commonly seen in refineries includes reforming raffinate oil, DCC hydrogenated gasoline raffinate oil and the like, and with the development of oil conversion trend in the refining and chemical industry, the demand for gasoline blending has decreased, so it is of great significance to convert these naphtha fractions into propane, n-butane and other low-carbon chemical light hydrocarbons by hydrocracking, to provide raw materials for chemical devices and to improve the added value of oil products.

[0005] CN106062148A discloses a process for converting hydrocarbons into olefins, in which naphtha as a representative of hydrocarbon raw materials is separated into multiple streams classified by carbon number through a hydrocracking unit, and suitable streams are respectively fed into 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℃, a pressure of 0.6-3.0 MPa gauge pressure and a mass space velocity of 0.2-10 h -1 -1.

[0006] CN12409121A discloses a method for converting light naphtha into low-carbon olefins and aromatic hydrocarbons, in which light naphtha with a C5, C6 alkane content of 99% is subjected to normal-isomer separation, the isomer component is fed into a hydrocracking unit and separated to obtain refinery dry gas, propane, n-butane and isobutane, and these components are further converted into ethylene and propylene through steam cracking or propane dehydrogenation units. The conditions of the hydrocracking unit in the method include a temperature of 330-360℃ and a pressure of 6-8 MPa gauge pressure, and after separation through the hydrocracking unit, the proportions of refinery dry gas, propane, n-butane and isobutane are 6%, 31%, 29% and 34% respectively.

[0007] CN108368435A discloses a method for maximum conversion of a feedstock containing middle distillate into C2 and C3 by providing multiple consecutive hydrocracking reaction zones to effectively reduce the carbon number of the feedstock, wherein the first hydrocracking zone requires a feedstock boiling point range of 180-360℃, reaction conditions of 300-400℃ temperature, 3-35MPa, the second hydrocracking reaction zone conditions are 300-450℃, 1200-4000kPa gauge pressure, mass space velocity of 0.1-15h -1 , the molar ratio of hydrogen to hydrocarbon material is 1:1-4:1, and the third hydrocracking reaction zone is carried out at a temperature of 425-580℃.

[0008] However, the prior art methods all have the defects of insufficient feedstock adaptability, harsh operating conditions, and limited propane yield. SUMMARY

[0009] The purpose of the present application is to provide a method for maximum conversion of lower value-added raffinate fraction into propane to solve the problem of excess naphtha such as raffinate in some refining enterprises.

[0010] To achieve the above-mentioned purpose, the present application provides a hydrocracking method for maximizing propane production from raffinate, which comprises:

[0011] (1) under low-pressure hydrogen conditions, the raffinate is sequentially introduced into a hydrocracking reaction zone I filled with a hydrocracking catalyst I and a hydrocracking reaction zone II filled with a hydrocracking catalyst II to carry out a hydrocracking reaction, and a hydrocracking product is obtained; the paraffin content in the raffinate is 48wt%-99wt%, and the total saturated hydrocarbon content is not less than 90wt%;

[0012] The hydrocracking catalyst I and the hydrocracking catalyst II both contain an acidic component, and the acidic component in the hydrocracking catalyst I is selected from at least one of a beta-type molecular sieve, a modified product of a beta-type molecular sieve, a Y-type molecular sieve, and a modified product of a Y-type molecular sieve, and the acidic component in the hydrocracking catalyst II is selected from at least one of a ZSM-type molecular sieve and a modified product of a ZSM-type molecular sieve;

[0013] (2) the hydrocracking product is separated to obtain a C3 / C4 product and light naphtha;

[0014] Wherein, the conditions of the hydrocracking reaction are controlled so that the conversion rate I of the hydrocracking reaction zone I is 5%-50%, and the conversion rate II of the overall hydrocracking reaction is 60%-99%.

[0015] The method provided by the application can produce the gas product mainly containing propane and n-butane in the largest amount from the raffinate oil fraction with low added value and almost no aromatic hydrocarbon under low-pressure hydrogen condition.

[0016] The treatment method provided by the application can balance the activity and stability of the hydrocracking catalyst, and convert the raffinate oil into high-quality chemical materials under high conversion rate. Preferably, the catalyst grading scheme is adjusted according to the content of naphthenes in the raw material, so as to realize the selective conversion of naphthenes and paraffins in the raw material in different zones, and convert the hydrocarbons in the raw material into the gas product rich in propane in the largest amount. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flowchart of the hydrocracking method for producing propane from raffinate oil.

[0018] REFERENCE NUMERALS

[0019] 1, 3, 5, 6, 8, 10, 12, 14, 15, 17, and 18 are pipelines

[0020] 2: raw material oil pump

[0021] 4: heating furnace

[0022] 7: hydrocracking reaction zone I

[0023] 9: hydrocracking reaction zone II

[0024] 11: high-pressure separator

[0025] 13: gas purification unit

[0026] 16: fractionation unit DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the application. The endpoints of the ranges and the values disclosed herein should be understood to be open-ended ranges. The ranges disclosed herein are also intended to cover any and all sub-ranges of the ranges. For example, a stated range of 1 to 10 should be considered to include any and all sub-ranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, as well as all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, i.e., all sub-ranges having a minimum value of equal to or greater than 1 and a maximum value of equal to or less than 10, when combined, are within the scope of the range of 1 to 10. The application includes ranges using a different language than those expressly stated above, such as "between" or "and". For example, a range of "between 1 and 10" should be considered to include any and all sub-ranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, as well as all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, i.e., all sub-ranges having a minimum value of equal to or greater than 1 and a maximum value of equal to or less than 10, when combined, are within the scope of the range of 1 to 10.

[0028] As described above, the application provides a hydrocracking method for producing propane from raffinate oil, which comprises:

[0029] (1) under low pressure and hydrogen condition, the raffinate oil is introduced into a hydrocracking reaction zone I filled with a hydrocracking catalyst I and a hydrocracking reaction zone II filled with a hydrocracking catalyst II in sequence to carry out hydrocracking reaction, and a hydrocracking product is obtained; the content of paraffin in the raffinate oil is 48wt%-99wt%, and the total content of saturated hydrocarbon is not less than 90wt%;

[0030] The hydrocracking catalyst I and the hydrocracking catalyst II both contain an acidic component, and the acidic component in the hydrocracking catalyst I is selected from 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, and the acidic component in the hydrocracking catalyst II is selected from at least one of a ZSM-type molecular sieve and a modified product of a ZSM-type molecular sieve;

[0031] (2) the hydrocracking product is separated to obtain a C3 / C4 product and light naphtha;

[0032] The conditions of the hydrocracking reaction are controlled so that the conversion rate I of the hydrocracking reaction zone I is 5%-50%, and the conversion rate II of the overall hydrocracking reaction is 60%-99%.

[0033] In the present application, the calculation method of the conversion rate I of the hydrocracking reaction zone I is: conversion rate I=(1-mass percentage content of C5+ hydrocarbons in the liquid product of the hydrocracking reaction zone I*yield of the liquid product of the hydrocracking reaction zone I / mass percentage content of C5+ hydrocarbons in the raffinate oil)*100%; and the calculation method of the conversion rate II of the overall hydrocracking reaction is: conversion rate II=(1-mass percentage content of C5+ hydrocarbons in the liquid product of the hydrocracking reaction zone II*yield of the liquid product of the hydrocracking reaction zone II / mass percentage of C5+ hydrocarbons generated by the hydrocracking reaction zone I)*100%.

[0034] The calculation method of the yield of the liquid product is: yield of the liquid product=mass of the liquid product at the outlet of the reaction zone / mass of the raw material at the inlet of the reaction zone*100%.

[0035] The method of the present application can make the mass yield of C3 in the product not less than 45%, and the selectivity of C3 not less than 55%.

[0036] The calculation method of the selectivity of C3 in the present application is: selectivity of C3=mass yield of C3 in the product / sum of mass yield of C3 and C4 in the product*100%.

[0037] The method of the present application can further comprise, before introducing the raffinate oil into the hydrocracking reaction zone for hydrocracking reaction, preheating the raffinate oil alone or together with hydrogen, for example, introducing into a heating furnace for preheating treatment; and then introducing the preheated material into the hydrocracking reaction zone for the hydrocracking reaction. The present application does not have a specific requirement for the temperature of preheating, which can be the temperature required for the hydrocracking reaction or slightly lower than the temperature required for the hydrocracking reaction.

[0038] Preferably, the conditions of the hydrocracking reaction are controlled so that the conversion rate I of the hydrocracking reaction zone I is 10% to 35%, and the conversion rate II of the overall hydrocracking reaction is 75% to 99%.

[0039] The raffinate oil of the present application can be a refinery light oil rich in saturated hydrocarbons.

[0040] Preferably, the raffinate oil has a carbon number of C5 to C12, a paraffin content of 48wt% to 95wt%, a naphthene content of 1wt% to 50wt%, and an aromatic content of 0wt% to 10wt%.

[0041] Particularly preferably, the content of the fraction having a carbon number of C5 to C10 in the raffinate oil is ≧80wt%, and the aromatic content in the raffinate oil is ≦3wt%. The inventors have found that in this preferred case, the propane yield and selectivity of the scheme of the present application are higher.

[0042] Preferably, the raffinate oil is selected from at least one of a reforming raffinate oil and a DCC gasoline hydrogenation device raffinate oil.

[0043] The method of the present application can process raw oil with various nitrogen contents; particularly preferably, the nitrogen content in the raffinate oil is ≦20μg / g.

[0044] Preferably, the nitrogen content in the raffinate oil is not higher than 20μg / g, and in this preferred case, it is not necessary to provide a hydrofining catalyst in the scheme of the present application.

[0045] Preferably, the pressure of the hydrocracking reaction is ≦8.0MPa.

[0046] Preferably, the temperature of the hydrocracking reaction zone I is 330 to 420℃, and the temperature of the hydrocracking reaction zone II is 280 to 420℃.

[0047] Preferably, the pressure of the hydrocracking reaction is 0.2 to 8.0MPa, the total volume space velocity of the feed is 0.1 to 20.0h -1 , and the hydrogen / oil volume ratio is 100 to 2000.

[0048] According to one preferred embodiment, each of the hydrocracking catalyst I and the hydrocracking catalyst II independently has the following characteristics: the hydrocracking catalyst contains a carrier and an active metal component, and the content of the active metal component is 10 to 50 wt% based on 100% by weight of the hydrocracking catalyst in terms of oxide; and the content of an acid component is 45 to 80 wt% based on 100% by weight of the carrier.

[0049] Preferably, the volume fraction of the hydrocracking catalyst I is 10 to 60% and the volume fraction of the hydrocracking catalyst II is 20 to 90% based on 100% of the total volume of the catalysts in the hydrocracking reaction.

[0050] Preferably, in the hydrocracking reaction zone I, a guard catalyst is further packed upstream of the hydrocracking catalyst I in the flow direction of the liquid phase stream in the hydrocracking reaction.

[0051] Preferably, the packing volume of the guard catalyst is ≯ 20% based on 100% of the total volume of the catalysts in the hydrocracking reaction.

[0052] According to one preferred embodiment, each of the hydrocracking catalyst I and the hydrocracking catalyst II independently has the following characteristics:

[0053] In the carrier of the hydrocracking catalyst, a heat-resistant inorganic oxide is further contained, and the heat-resistant inorganic oxide is selected from at least one of silicon oxide and aluminum oxide.

[0054] Particularly preferably, each of the hydrocracking catalyst I and the hydrocracking catalyst II independently has the following characteristics:

[0055] In the carrier of the hydrocracking catalyst, the active metal element in the active metal component is selected from at least two of a Group VIB metal element and a Group VIII metal element; and the content of the Group VIB metal element is 5 to 35 wt% and the content of the Group VIII metal element is 1 to 8 wt% based on 100% of the total weight of the hydrocracking catalyst in terms of oxide.

[0056] Preferably, the guard catalyst is selected from at least one of a hydrogenation guard catalyst, a hydrodearsenization catalyst, a hydrodechlorination catalyst, and a hydrodemetallization catalyst.

[0057] According to one preferred embodiment, the hydrogenation guard catalyst contains a guard catalyst carrier and a guard catalyst active metal component, the guard catalyst carrier is alumina, and the guard catalyst active metal component contains at least one element selected from a Group VIII metal element and at least one element selected from a Group VIB metal element.

[0058] Preferably, in the hydrogen protection catalyst, the content of the Group VIII metal element is 0.3wt% to 5wt% and the content of the Group VIB metal element is 1wt% to 30wt% based on the total weight of the hydrogen protection agent in terms of oxide.

[0059] Preferably, in the hydrogen protection catalyst, the active metal component of the protection agent contains at least one of nickel element and cobalt element, and contains at least one of molybdenum element and tungsten element.

[0060] According to another preferred embodiment, the content of arsenic in the raffinate oil is 1μg / g to 30μg / g, and the protection catalyst contains the hydrogen dearsenization catalyst.

[0061] Preferably, the carrier of the hydrogen dearsenization catalyst is alumina, the active metal component contains at least one of nickel element and cobalt element, and contains at least one of molybdenum element and tungsten element, the total content of the nickel and / or cobalt is 0.1wt% to 6wt% in terms of oxide, and the total content of the molybdenum and / or tungsten is 1wt% to 20wt%.

[0062] According to still another preferred embodiment, the total metal content in the raffinate oil is 0.1wt% to 2wt%, and the protection catalyst contains the hydrogen demetallization catalyst.

[0063] Preferably, the carrier of the hydrogen demetallization catalyst is alumina, the active metal component contains at least one of nickel element and cobalt element, and contains at least one of molybdenum element and tungsten element, the total content of the nickel and / or cobalt is 1wt% to 3wt% in terms of oxide, and the total content of the molybdenum and / or tungsten is 1wt% to 30wt%.

[0064] The present application does not have specific requirements for the separation method in step (2), and those skilled in the art can use the known separation methods in the art, for example, gas-liquid separation, fractionation, etc. The examples of the present application exemplarily provide a specific separation method, and those skilled in the art should not understand it as a limitation on the protection scope of the present application.

[0065] The separation of the present application can be carried out by gas-liquid separation in a separator (for example, a high-pressure separator). The gas product obtained after the gas-liquid separation can be recycled back to the device for the hydrocracking reaction after purification. The liquid product obtained after the gas-liquid separation is preferably further fractionated to obtain the C3 / C4 product and the light naphtha.

[0066] The light naphtha product obtained by the present application can be mixed with the raw oil as unconverted oil according to the production needs, and then recycled to the reaction system for full conversion, or can be introduced into the device. The present application does not have special requirements for this.

[0067] The process flow diagram shown below provides a preferred embodiment of a hydrocracking method for producing propane from raffinate oil according to the present application, and specifically, the method comprises: Figure 1

[0068] (1) Under low-pressure hydrogen conditions, the raffinate oil is introduced into the heating furnace 4 through the pipeline 1, the raw oil pump 2 and the pipeline 3 for preheating, and hydrogen is introduced into the heating furnace 4 through the pipeline 5, to obtain a preheated material; the preheated material is introduced into the hydrocracking reaction zone I 7 filled with hydrocracking catalyst I through the pipeline 6 for hydrocracking reaction, and the stream obtained in the hydrocracking reaction zone I is introduced into the hydrocracking reaction zone II 9 filled with hydrocracking catalyst II through the pipeline 8 for hydrocracking reaction, to obtain a hydrocracking product;

[0069] (2) The hydrocracking product is introduced into the high-pressure separator 11 through the pipeline 10 for gas-liquid phase separation; the gas phase flowing out of the high-pressure separator 11 enters the gas purification unit 13 through the pipeline 12, and the purified gas can be mixed with the new hydrogen through the pipeline 14 and the pipeline 5; the liquid phase flowing out of the high-pressure separator 11 enters the fractionation unit 16 through the pipeline 15, and the gas phase rich in propane is introduced into the device through the pipeline 18; the light naphtha containing C5 and above components is introduced from the pipeline 17 after fractionation in the fractionation unit, and this part of the light naphtha can also be mixed with the raw oil from the pipeline as unconverted oil according to the production needs, and then recycled to the reaction system for full conversion. The present application will be described in detail through examples below. In the examples below, the raw materials used are ordinary commercially available products unless otherwise specified.

[0070] In the examples below, the process flow shown in Figure 1 is used unless otherwise specified.

[0071] The properties of the raffinate oil used below are listed in Table 1; the cases of the catalysts used are listed in Table 2.

[0072] The catalysts provided in Table 2 are all prepared by methods known in the art, for example, the preparation method provided in document CN112742440A can be used.

[0073] Table 1: Properties of raffinate oil

[0074]

[0075] Table 2: Catalyst cases​

[0076]

[0077]

[0078] Example 1

[0079] The process flow shown in Figure 1 was used, and no guard catalyst was provided in the hydrocracking reaction zone. The process parameters involved are listed in Table 3. Figure 1 The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0080] The distribution and properties of the products obtained are listed in Table 4.

[0081] Example 2

[0082] The process flow shown in Figure 1 was used, and no guard catalyst was provided in the hydrocracking reaction zone. The process parameters involved are listed in Table 3. Figure 1 The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0083] The distribution and properties of the products obtained are listed in Table 4.

[0084] Example 3

[0085] The process flow shown in Figure 1 was used, and a hydrodechlorination catalyst and a hydrocracking catalyst were provided in the hydrocracking reaction zone. The process parameters involved are listed in Table 3. Figure 1 The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0086] The distribution and properties of the products obtained are listed in Table 4.

[0087] Comparative Example 1

[0088] The process flow shown in Figure 1 was used, and no guard catalyst was provided in the hydrocracking reaction zone. The process parameters involved are listed in Table 3. Figure 1 The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0089] The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0090] Comparative Example 2

[0091] The process flow shown in Figure 1 was used, and no guard catalyst was provided in the hydrocracking reaction zone. The process parameters involved are listed in Table 3. Figure 1 The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0092] The reaction product was fractionated into gas and a small amount of light naphtha fraction.

[0093] Comparative Example 3

[0094] The process flow shown in the figure is adopted, and no guard catalyst is arranged in the hydrocracking reaction zone, and the process parameters involved are listed in Table 3. Figure 1

[0095] The reaction product can be divided into gas and a small amount of light naphtha fraction by fractionation.

[0096] Table 3

[0097]

[0098] The volume percentage of the catalyst involved in Table 3 is calculated based on the total catalyst loading volume of the hydrocracking reaction.

[0099] Table 4

[0100]

[0101] The method of the present application can maximize the yield of propane, reduce the content of naphthenes, and enrich paraffins by selectively converting naphthenes and paraffins in the raw material. In addition, a small amount of naphtha product can be recycled to further improve the yield of propane.

[0102] In addition, as shown in Example 3, the raffinate oil raw material used contains chlorine due to the processing of the upstream device, and a hydrogenation dechlorination catalyst can be used to remove chlorine in the raw material to prevent device corrosion. After removal, the cracking section feed requirement is met, the production of propane can be maximized, and the product distribution can be consistent with the raw material without the need for dechlorination.

[0103] The present application can maximize the conversion of raw materials with high saturated hydrocarbons.

[0104] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.​

Claims

1. A hydrocracking process for maximizing production of propane from raffinate oil, characterized in that, The method comprises: (1) under low-pressure hydrogen conditions, the raffinate oil is introduced into a hydrocracking reaction zone I filled with a hydrocracking catalyst I and a hydrocracking reaction zone II filled with a hydrocracking catalyst II in sequence to perform a hydrocracking reaction, and a hydrocracking product is obtained; the paraffin content in the raffinate oil is 48wt%-99wt%, the total saturated hydrocarbon content is not less than 90wt%, and the pressure of the hydrocracking reaction is ≯8.0MPa; The hydrocracking catalyst I and the hydrocracking catalyst II both contain an acidic component, and the acidic component in the hydrocracking catalyst I is selected from 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, and the acidic component in the hydrocracking catalyst II is selected from at least one of a ZSM-type molecular sieve and a modified product of a ZSM-type molecular sieve; (2) the hydrocracking product is separated to obtain a C3 / C4 product and light naphtha; The conditions of the hydrocracking reaction are controlled so that the conversion rate I of the hydrocracking reaction zone I is 5%-50%, and the conversion rate II of the overall hydrocracking reaction is 60%-99%; The conversion rate I = (1-the mass percentage content of hydrocarbons with C5 and above in the liquid product of the hydrocracking reaction zone I * the yield of the liquid product of the hydrocracking reaction zone I / the mass percentage content of hydrocarbons with C5 and above in the raffinate oil) * 100%; The conversion rate II = (1-the mass percentage content of hydrocarbons with C5 and above in the liquid product of the hydrocracking reaction zone II * the yield of the liquid product of the hydrocracking reaction zone II / the mass percentage of hydrocarbons with C5 and above generated by the hydrocracking reaction zone I) * 100%; The yield calculation method of the liquid product is: the yield of the liquid product = the mass of the liquid product at the outlet of the reaction zone / the mass of the raw material at the inlet of the reaction zone * 100%.

2. The hydrocracking process of claim 1 wherein, The conditions of the hydrocracking reaction are controlled so that the conversion rate I of the hydrocracking reaction zone I is 10%-35%, and the conversion rate II of the overall hydrocracking reaction is 75%-99%.

3. The hydrocracking process of claim 1 wherein, The raffinate oil has a carbon number of C5-C12, a paraffin content of 48wt%-95wt%, a naphthene content of 1wt%-50wt%, and an aromatic hydrocarbon content of 0wt%-10wt%.

4. The hydrocracking process of claim 3, wherein, The content of the fraction with a carbon number of C5-C10 in the raffinate oil is ≮80wt%, and the aromatic hydrocarbon content in the raffinate oil is ≯3wt%.

5. The hydrocracking process of claim 3 wherein, The raffinate oil is selected from at least one of a reforming raffinate oil and a DCC gasoline hydrogenation device raffinate oil.

6. The hydrocracking process of claim 1 wherein, The nitrogen content in the raffinate oil is ≯20μg / g.

7. The hydrocracking process of any of claims 1-6, wherein, The temperature of the hydrocracking reaction zone I is 330-420℃, and the temperature of the hydrocracking reaction zone II is 280-420℃.

8. The hydrocracking process of any of claims 1-6, wherein, The pressure of the hydrocracking reaction is 0.2-8.0 MPa, the total volume space velocity of the feed is 0.1-20.0 h -1 , and the hydrogen-oil volume ratio is 100-2000.

9. The hydrocracking process of any of claims 1-6, wherein, The hydrogenation cracking catalyst I and the hydrogenation cracking catalyst II each independently has the following characteristics: the hydrogenation cracking catalyst contains a carrier and an active metal component, the content of the active metal component in terms of oxide is 10wt%-50wt% based on 100% by weight of the hydrogenation cracking catalyst; the content of an acid component is 45wt%-80wt% based on 100% by weight of the carrier.

10. The hydrocracking process of any of claims 1-6, wherein, The volume fraction of the hydrogenation cracking catalyst I is 10%-60% and the volume fraction of the hydrogenation cracking catalyst II is 20%-90% based on 100% by volume of the total catalyst in the hydrogenation cracking reaction.

11. The hydrocracking process of claim 10, wherein, In the hydrogenation cracking reaction zone I, a guard catalyst is also packed upstream of the hydrogenation cracking catalyst I in the flow direction of the liquid phase stream in the hydrogenation cracking reaction.

12. The hydrocracking process of claim 11, wherein, The packing volume of the guard catalyst is ≯20% based on 100% by volume of the total catalyst in the hydrogenation cracking reaction.

13. The hydrocracking process of claim 9, wherein, The hydrogenation cracking catalyst I and the hydrogenation cracking catalyst II each independently has the following characteristics: In the carrier of the hydrogenation cracking catalyst, a heat-resistant inorganic oxide is further contained, and the heat-resistant inorganic oxide is selected from at least one of silicon oxide and aluminum oxide.

14. The hydrocracking process of claim 9, wherein, The hydrogenation cracking catalyst I and the hydrogenation cracking catalyst II each independently has the following characteristics: In the hydrogenation cracking catalyst, the active metal element in the active metal component is selected from at least one of a group VIB metal element and at least one of a group VIII metal element; the content of the group VIB metal element is 5wt%-35wt% and the content of the group VIII metal element is 1wt%-8wt% in terms of oxide based on the total weight of the hydrogenation cracking catalyst.

15. The hydrocracking process of claim 11, wherein, The guard catalyst is selected from a hydrogenation guard catalyst.

16. The hydrocracking process of claim 11, wherein, The guard catalyst is selected from at least one of a hydrogenation arsenic removal catalyst, a hydrogenation chlorine removal catalyst and a hydrogenation metal removal catalyst.

17. The hydrocracking process of claim 15, wherein, The hydrogenation guard catalyst contains a guard carrier and a guard active metal component, the guard carrier is aluminum oxide, and the guard active metal component contains at least one element selected from a group VIII metal element and at least one element selected from a group VIB metal element.

18. The hydrocracking process of claim 17, wherein, In the hydrogenation guard catalyst, the content of the group VIII metal element is 0.3wt%-5wt% and the content of the group VIB metal element is 1wt%-30wt% in terms of oxide based on the total weight of the hydrogenation guard catalyst.

19. The hydrocracking process of claim 17, wherein, In the hydrogenation guard catalyst, the guard active metal component contains at least one of a nickel element and a cobalt element, and contains at least one of a molybdenum element and a tungsten element.

20. The hydrocracking process of claim 16, wherein, The content of arsenic in the raffinate oil is 1μg / g-30μg / g, and the guard catalyst contains the hydrogenation arsenic removal catalyst.

21. The hydrocracking process of claim 20, wherein, The carrier of the hydrogenation arsenic removal catalyst is aluminum oxide, the active metal component contains at least one of a nickel element and a cobalt element, and contains at least one of a molybdenum element and a tungsten element, the total content of the nickel and / or cobalt is 0.1wt%-6wt% and the total content of the molybdenum and / or tungsten is 1wt%-20wt% in terms of oxide.

22. The hydrocracking process of claim 15, wherein, The total metal content in the raffinate oil is 0.1wt%-2wt%, and the protection catalyst contains a hydrodemetallization catalyst.

23. The hydrocracking process of claim 22, wherein, The hydrodemetallization catalyst carrier is alumina, the active metal component contains at least one of nickel element and cobalt element, and contains at least one of molybdenum element and tungsten element, the total content of the nickel and / or cobalt is 1wt%-3wt% in terms of oxide, and the total content of the molybdenum and / or tungsten is 1wt%-30wt%.

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