A hydrocracking method for improving the color stability of special oil

Abstract

The application discloses a hydrocracking method for improving color stability of special oil. The method is a one-stage series hydrocracking process, wherein a hydrocracking catalyst bed and a post hydrofining catalyst bed are arranged in sequence along the liquid phase material flow direction in a hydrocracking reactor, and the method comprises the following steps: a wax oil raw material is sequentially introduced into a hydrofining reactor and a hydrocracking reactor, and the obtained product is separated and fractionated to obtain an industrial white oil fraction; wherein, a material P is introduced between the hydrocracking catalyst bed and the post hydrofining catalyst bed, the material P is one or more of C17-C22 phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones and aromatic esters; an air cooling device is arranged before fractionation of the obtained product, wherein the air cooling device is water injected so that the material P in the product is taken out of the reaction system by the water phase. The method can improve the color stability of the special oil under the condition that the hydrocracking device is mainly used for producing the special oil.

Description

Technical Field

[0001] This invention relates to the field of hydrocracking technology, specifically to a hydrocracking method for improving the color stability of specialty oil products. Background Technology

[0002] In recent years, the demand for refined oil products has undergone significant changes, with a gradual decline in demand for diesel and gasoline, while the demand for specialty oils has grown rapidly. The hydrocracking process can produce industrial white oil components such as polyester fiber oil, transformer oil, and white oil, which are essentially hydrocracking diesel fractions. However, these components often suffer from poor color stability, resulting in products that do not meet technical requirements. The conventional hydrocracking process for producing industrial white oil involves: wax oil feedstock and hydrogen sequentially entering a hydrorefining reactor and a hydrocracking reactor. The resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, industrial white oil, and tail oil fractions. Currently, to improve the color stability of industrial white oil, it is generally fed into a separate hydrorefining reactor for further hydrogen saturation to meet quality requirements. This leads to increased production costs and a significant decrease in production efficiency. Therefore, developing technologies to improve the color stability of hydrocracking specialty oil products is of significant practical importance.

[0003] CN116286087A discloses a method for producing high-quality industrial white oil using a wax oil hydrocracking unit. The method involves sequentially feeding wax oil feedstock into a hydrorefining reactor and a hydrocracking reactor. In the hydrocracking reactor, the reaction products undergo gas-liquid separation via a thermal separator and a cold separator, then proceed to a stripping tower, and finally to a fractionation tower. Diesel fuel is drawn from the 45th tray and sent to the diesel stripping tower, where the stripping steam volume is increased by 1-3 times. Light components from the unconverted oil in the unit are extracted as white oil fractions. This method has limitations regarding the proportion of wax oil in the feedstock and has limited applicability. Furthermore, the fractionation tower requires temperature control within a narrow range to maintain the aromatic content of the white oil, making the control process relatively cumbersome.

[0004] CN117660056A discloses a combined method for producing industrial white oil. The method includes: feeding oil into a hydrocracking unit for reaction; solvent extraction of the resulting light diesel oil fraction to obtain raffinate and extracted oil; and mixing the raffinate with the heavy diesel oil fraction obtained from the hydrocracking unit to obtain the industrial white oil product. This method has a cumbersome process flow and low efficiency in producing industrial white oil. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hydrocracking method for improving the color stability of specialty oils. This method can improve the color stability of specialty oils in hydrocracking units where the primary goal is to produce specialty oils.

[0006] This invention provides a hydrocracking method for improving the color stability of specialty oils. The method employs a single-stage tandem hydrocracking process, wherein a hydrocracking catalyst bed and a post-hydrorefining catalyst bed are sequentially arranged in the hydrocracking reactor along the liquid phase stream direction. The method includes: a wax oil feedstock sequentially enters a hydrorefining reactor and a hydrocracking reactor; the resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, industrial white oil, and tail oil fractions; wherein a material P is introduced between the hydrocracking catalyst bed and the post-hydrorefining catalyst bed, wherein material P is one or more of C17-C22 phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, and aromatic esters; an air-cooling device is installed before the fractionation of the resulting products, wherein the air-cooling device is injected with water so that material P in the products is carried out of the reaction system by the aqueous phase.

[0007] In the method of this invention, both the hydrorefining reactor and the hydrocracking reactor are fixed-bed reactors.

[0008] In the method of this invention, the hydrorefining reactor adopts a conventional top-feed, bottom-discharge method. In the hydrocracking reactor, the hydrorefined stream and hydrogen gas adopt a top-feed, bottom-discharge method.

[0009] In the method of this invention, the initial boiling point of the wax oil feedstock is generally 200℃~350℃, and the dry point is generally 500℃~600℃, preferably 530℃~590℃; the nitrogen content is below 2500μg / g, generally 500μg / g~2000μg / g; the sulfur content is not strictly limited, and the content of other impurities only needs to meet conventional requirements. The wax oil feedstock can be at least one of various straight-run or secondary-processed wax oils obtained from processing naphthenic crude oil, intermediate-based crude oil, or paraffinic crude oil, preferably straight-run wax oil components or deasphalted oils from primary-processed paraffinic crude oil, which can be selected from at least one of various vacuum gas oils (VGO) and deasphalted oils (DAO) obtained from processing paraffinic crude oil, such as Daqing VGO, DAO, Changqing VGO, DAO, Shengli VGO, DAO, or several of them. The hydrogen gas is a feedstock with a commonly used industrial impurity content that meets the requirements.

[0010] In the method of this invention, the operating conditions of the hydrorefining reactor are as follows: the reaction temperature is 300℃~420℃, preferably 310℃~390℃; the reactor inlet pressure is 6MPa~20MPa, preferably 8MPa~18MPa; and the volume hourly space velocity is 0.5h⁻¹. -1 ~3.0h -1 0.6h is preferred -1 ~2.5h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–1200, preferably 500–1100.

[0011] In the method of this invention, the hydrorefining catalyst loaded in the hydrorefining reactor and the post-hydrorefining catalyst loaded in the hydrocracking reactor can be conventional hydrocracking pretreatment catalysts, or the required catalysts can be prepared according to common knowledge in the art. Conventional hydrocracking pretreatment catalysts include a support and a hydrogenation metal. Based on the weight of the catalyst, they typically include a Group VIB metal component from the periodic table, such as tungsten and / or molybdenum, with a mass content of 10%–35% (based on oxides), preferably 15%–30%, and a Group VIII metal, such as nickel and / or cobalt, with a mass content of 1%–7% (based on oxides), preferably 1.5%–6%. The support is an inorganic refractory oxide, generally selected from at least one of alumina, amorphous aluminum silicate, silica, titanium dioxide, etc. The preferred metal for the hydrorefining catalyst is a Mo-Ni combination with a specific surface area ≥160 m². 2 / g, pore volume ≥0.3mL / g. The preferred metal catalyst for post-hydrogenation refining is a Mo-Co combination with a specific surface area ≥160m². 2 / g, pore volume ≥0.3mL / g. The conventional hydrocracking pretreatment catalyst can be any of the existing commercial catalysts, such as the 3936, 3996, FF-12, FF-16, FF-26, FF-36, FF-46, and FF-66 catalysts developed by the Fushun Petrochemical Research Institute (FRIPP). The refining reaction is a process of removing impurities such as desulfurization, denitrification, and aromatic saturation. The hydrorefining catalyst and the post-hydrorefining catalyst can be the same or different.

[0012] In the method of this invention, the operating conditions of the hydrocracking catalyst bed in the hydrocracking reactor in step (2) are as follows: the reaction temperature is 350℃~388℃, preferably 365℃~376℃; the reactor inlet pressure is 12MPa~20MPa, preferably 15MPa~17MPa; and the volume hourly space velocity is 0.5h. -1 ~5.0h -1 0.6h is preferred -1 ~3.0h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–2000, preferably 500–1100.

[0013] In the method of this invention, the operating conditions of the hydrorefining catalyst bed after the hydrocracking reactor in step (2) are as follows: the reaction temperature is 360℃~435℃, preferably 375℃~430℃; the volume hourly space velocity of the hydrocracking bed products is 10h. -1 ~25h -1 12h preferred -1 ~20h -1The hydrogen-to-oil volume ratio is 400–2000, preferably 500–1100, and the reactor inlet pressure is 6 MPa–20 MPa, preferably 8 MPa–18 MPa. Generally, the reaction temperature of the post-hydrogenation refining catalyst bed is 390℃–430℃ during the later stages of operation.

[0014] In the method of this invention, the hydrocracking catalyst is a conventional hydrocracking catalyst used for the production of specialty oils (industrial white oil). It can be a flexible hydrocracking catalyst, generally comprising a cracking component and a hydrogenation component, and may also include a binder. The cracking component typically includes at least one amorphous silica-alumina and / or molecular sieves, such as Y-type, β-type, or USY molecular sieves, and the binder is typically alumina and / or silica. The hydrogenation component is selected from at least one metal, metal oxide, or metal sulfide from Group VIB, Group VIIB, or Group VIII, with the hydrogenation metal more preferably being one or more of iron, chromium, molybdenum, tungsten, cobalt, and nickel. Based on the weight of the catalyst, the hydrogenation component, calculated as oxides, has a content of 28%–35%, preferably 25%–31%, the molecular sieve content is 26%–40%, preferably 28%–36%, and the remainder is amorphous silica-alumina and / or binder components. Conventional hydrocracking catalysts can be selected from various existing commercial catalysts, such as the 3976, FC-46, and FC-12 catalysts developed by FRIPP. Specific hydrocracking catalysts can also be prepared according to common knowledge in the field.

[0015] In the method of the present invention, the material P is selected from one or more of phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, and aromatic esters of C17-C22, and is further selected from one or more of phenyl dodecanoate, diphenyl m-phthalate, phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, phenylphenone, and phenolnaphthalene.

[0016] In the method of the present invention, preferably, relative to the post-hydrorefining catalyst, the volume hourly space velocity of the material P accounts for 28% to 72% of the total volume hourly space velocity of the hydrocracking bed products and the material P, more preferably 30% to 60%, for example, but not limited to 30%, 32%, 35%, 40%, 50%, 55%, 60%, etc., and any value within the range formed by any two of these values.

[0017] In the method of the present invention, preferably, the tail oil product obtained from the fractionation system is recycled to the inlet of the hydrorefining reactor.

[0018] The inventors discovered that the main reason for the poor color stability of specialty oil products produced by hydrocracking units is that components such as tetrahydronaphthalenes and indenes undergo dehydrogenation reactions in the post-refining catalyst reaction zone, generating components with higher unsaturation levels, such as naphthalenes and indenes. These components cause a decline in color stability. Effectively retaining components such as tetrahydronaphthalenes and indenes would be highly beneficial to the color stability of specialty oil products. Further research by the inventors revealed that material P will react at relatively low space velocities (1.5–3.0 h⁻¹). -1 The hydrodeoxygenation reaction is carried out at relatively low temperatures (300–330 °C), but post-hydrogenation purification at high space velocities (2.8–18.0 h⁻¹) is necessary. -1 Deoxygenation reactions are difficult to occur under high-temperature (360℃~435℃) reaction environments. Therefore, introducing material P before post-hydrocracking refining in the hydrocracking reactor can inhibit the dehydrogenation reaction of components such as tetrahydronaphthalene and indane in the material during post-refining, which helps to efficiently retain components such as tetrahydronaphthalene and indane. At the same time, material P is highly soluble in water, so material P can be effectively removed before product fractionation. Thus, it will not only not affect the yield and composition of specialty oils, but also ensure that the color stability of specialty oils is effectively improved, so that they can be shipped as high-quality specialty oils.

[0019] Further research by the inventors revealed that the content of C18-C20 bicyclic compounds in the hydrocracking catalyst bed products changes before and after passing through the post-hydrorefining catalyst bed. When the C18-C20 bicyclic compounds undergo dehydrogenation reactions due to contact with the post-hydrorefining catalyst, resulting in a retention rate below 80%, it significantly affects the color stability of specialty oils. Therefore, feedstock P is added to inhibit the dehydrogenation reaction of C18-C20 bicyclic compounds. However, since there is a chemical reaction equilibrium between feedstock P, hydrocracking bed products, and the post-hydrorefining catalyst, the dehydrogenation reaction of C18-C20 bicyclic compounds cannot be completely prevented. Preferably, a certain retention rate is controlled.

[0020] In the method of this invention, preferably, after the hydrocracking bed product stream passes through the post-hydrocracking refining catalyst, the retention rate of C18-C20 bicyclic compounds in the obtained post-refined product is above 80 wt%, more preferably 82 wt% to 97 wt%. Wherein, the retention rate of C18-C20 bicyclic compounds = (concentration of C18-C20 bicyclic compounds in the post-refined product / concentration of C18-C20 bicyclic compounds in the hydrocracking bed product stream) * 100%.

[0021] Hydrocracking units typically involve a separation process (generally including hot high-performance fraction, hot low-performance fraction, cold high-performance fraction, and cold low-performance fraction) before fractionation of the hydrocracking products. This process separates the gaseous components from the products, improving the efficiency of the fractionation process and reducing energy consumption. Specifically, a water injection process occurs after the hot high-performance fraction and before air cooling. This is to prevent the precipitation of ammonium salts during the cooling process, which could clog pipelines and equipment. Since the material P in the method of this invention is highly soluble in water, it can be carried out of the reaction system by the aqueous phase.

[0022] In the method of the present invention, an air cooling device is set up before the fractionation of the obtained product. The air cooling device is injected with water so that the material P in the product is carried out of the reaction system by the aqueous phase. The amount of water injected is 2 to 30 times the mass flow rate of material P, preferably 3 to 9 times the mass flow rate of material P.

[0023] In the method of this invention, the subsequent product separation, fractionation process and various qualified products are all conventional technical contents familiar to those skilled in the art, and will not be described in detail here.

[0024] In the method of this invention, the final boiling point of light naphtha is 50-68℃, preferably 55-62℃; the initial boiling point of heavy naphtha is 55-75℃, preferably 60-68℃, and the final boiling point is 120-190℃, preferably 145-180℃; the initial boiling point of aviation kerosene is 160-200℃, preferably 170-185℃, and the final boiling point is 200-230℃, preferably 205-215℃; the initial boiling point of industrial white oil is 200-270℃, preferably 210-265℃, and the final boiling point is 300-360℃, preferably 310-340℃; and the initial boiling point of tail oil is 320-390℃, preferably 325-385℃.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The catalysts used in the hydrocracking unit in the method of the present invention are all conventional catalysts, and there is no need to develop new catalysts;

[0027] (2) In the method of the present invention, the color stability of special oil is specifically improved by introducing material P, without causing changes in product distribution and other product properties;

[0028] (3) In the method of the present invention, material P is soluble in water and can be discharged from the system with the demineralized water during the separation of hydrocracking products. It will not enter the fractionation system, so that the special oil components will not have any impurities. The process is energy-saving and efficient.

[0029] (4) The method of the present invention has strong applicability and can improve the color stability of special oils for any hydrocracking catalyst and process conditions. The adjustment method is flexible. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process of the present invention;

[0031] The annotations in the attached figures are explained as follows:

[0032] 1-Feedstock oil and hydrogen, 2-Hydrorefining reactor, 3-Hydrorefining product, 4-Hydrocracking reactor, 5-Hydrocracking catalyst bed, 6-Post-hydrorefining catalyst bed, 7-Feed P, 8-Hydrocracking product, 9-Water, 10-Air cooler, 11-Cooled material, 12-Cold high-efficiency fractionator, 13-Cold high-efficiency gas phase component, 14-Acidic water, 15-Cold high-efficiency oil phase component, 16-Cold low-efficiency fractionator, 17-Cold low-efficiency gas phase component, 18-Cold low-efficiency oil phase component, 19-Fracturing system, 20-Naphtha, 21-Jet fuel, 22-Industrial white oil, 23-Tail oil. Detailed Implementation

[0033] The method of the present invention will be described in more detail below with reference to specific embodiments and comparative examples.

[0034] The hydrocracking method for improving the color stability of specialty oils provided by this invention, such as... Figure 1 As shown, it includes:

[0035] Feedstock oil and hydrogen 1 are sequentially passed through hydrorefining reactor 2 and hydrocracking reactor 4 (equipped with hydrocracking catalyst bed 5 and post-hydrorefining catalyst bed 6). Material P7 is introduced between the hydrocracking catalyst bed 5 and the post-hydrorefining catalyst bed 6. The product from the hydrocracking bed and material P7 are passed together through the post-hydrorefining catalyst bed 6 to obtain hydrocracking product 8. Hydrocracking product 8 is mixed with water 9 and then cooled in air cooler 10. The cooled material 11 enters cold high-efficiency separator 12 for separation to obtain cold high-efficiency gas phase component 13, cold high-efficiency oil phase component 15, and acidic water 14. The acidic water 14 contains material P7 dissolved in the water. The cold high-grade oil phase component 15 enters the cold low-grade separator 16 for separation, yielding the cold low-grade gas phase component 17 and the cold low-grade oil phase component 18. The cold low-grade oil phase component 18 enters the fractionation system 19 for separation, yielding naphtha 20, jet fuel 21, industrial white oil 22, and tail oil 23. The tail oil 23 is recycled to the inlet of the hydrorefining reactor.

[0036] In the embodiments and comparative examples of the present invention, the distillation range of light naphtha is the fraction below 62°C, the distillation range of heavy naphtha is 62 to 178°C, the distillation range of jet fuel is 178 to 213°C, the distillation range of industrial white oil is 213 to 340°C, and the tail oil is the fraction above 340°C.

[0037] The properties of the feedstock used in the following examples and comparative examples are shown in Table 1, and the main properties of the catalysts used in the examples and comparative examples are shown in Table 2.

[0038] Table 1 Main Properties of Crude Oil

[0039] project crude oil type Straight-run wax oil <![CDATA[Density, g / cm 3 > 0.9032 Distillation range, °C 305～535 S, wt% 1.37 N, μg / g 1098

[0040] Table 2 Main properties of the catalyst

[0041]

[0042] Example 1

[0043] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used, and post-hydrorefining catalyst A is used again. Feed P uses phenyl dodecanoate and diphenyl m-phthalate (with a mass ratio of phenyl dodecanoate to diphenyl m-phthalate of 0.5:2.1). All tail oil is recycled to the inlet of the hydrorefining reactor, controlling the single-pass conversion rate to approximately 65%. Samples are taken to analyze the properties of the industrial white oil product.

[0044] Example 2

[0045] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used, and post-hydrorefining catalyst C is used. Feed P consists of phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, and phenylphenone (where the mass ratio of phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, and phenylphenone is 0.7:2.2:0.8:1.5). All tail oil is recycled to the inlet of the hydrorefining reactor, controlling the single-pass conversion rate to approximately 65%. Samples are taken to analyze the properties of the industrial white oil product.

[0046] Example 3

[0047] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used, and post-hydrorefining catalyst C is used. Material P consists of diphenyl phthalate, phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, phenylphenone, and phenolnaphthalene (where the mass ratio of diphenyl phthalate, phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, phenylphenone, and phenolnaphthalene is 2.8:1.3:0.6:0.8:0.3:0.9). All tail oil is recycled to the inlet of the hydrorefining reactor, controlling the single-pass conversion rate to approximately 70%. Samples are taken and analyzed to determine the properties of the industrial white oil product.

[0048] Comparative Example 1

[0049] Compared with Example 1, the only difference is that material P is not introduced and water is injected into the air-cooled room in a conventional manner.

[0050] A conventional single-stage series process is adopted. Catalyst A is used for hydrorefining, catalyst B is used for hydrocracking, and catalyst A is used for post-hydrorefining. All tail oil is recycled to the inlet of the hydrorefining reactor, and the single-pass conversion rate is controlled at approximately 65%. Samples are taken and analyzed to determine the properties of the industrial white oil product.

[0051] Comparative Example 2

[0052] Compared with Example 3, the only difference is that material P is not introduced and water is injected into the air-cooled room in a conventional manner.

[0053] A conventional single-stage series process was adopted. Catalyst A was used for hydrorefining, catalyst B for hydrocracking, and catalyst C for post-hydrorefining. All tail oil was recycled to the inlet of the hydrorefining reactor, and the single-pass conversion rate was controlled at approximately 70%. Samples were taken and analyzed to determine the properties of the industrial white oil product.

[0054] Comparative Example 3

[0055] The difference compared to Example 3 is that the material P is different.

[0056] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used, and post-hydrorefining catalyst C is used. Feedstock P consists of propyne aldehyde, pentenal, and 3-buten-1-ol (with a mass ratio of 1:2.5:0.8). All tail oil is recycled to the inlet of the hydrorefining reactor, controlling the single-pass conversion rate to approximately 70%. Samples are taken and analyzed to determine the properties of the industrial white oil product.

[0057] The effects of the above embodiments and comparative examples are compared in Table 3.

[0058] Table 3. Reaction conditions and results for each embodiment and comparative example.

[0059]

[0060]

Claims

1. A hydrocracking method for improving the color stability of specialty oil products, employing a single-stage tandem hydrocracking process, wherein a hydrocracking catalyst bed and a post-hydrorefining catalyst bed are sequentially arranged in the hydrocracking reactor along the liquid phase stream direction, the method comprising: The wax oil feedstock is sequentially fed into a hydrorefining reactor and a hydrocracking reactor. The resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, industrial white oil, and tail oil fractions. A material P is introduced between the hydrocracking catalyst bed and the post-hydrorefining catalyst bed. Material P is one or more of C17-C22 phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, and aromatic esters. An air-cooling device is installed before the fractionation of the resulting products. This air-cooling device is injected with water so that material P in the products is carried out of the reaction system by the aqueous phase.

2. The method according to claim 1, characterized in that, Both the hydrorefining reactor and the hydrocracking reactor are fixed-bed reactors; the hydrorefining reactor adopts a conventional top-feed and bottom-discharge method; in the hydrocracking reactor, the hydrorefining stream and hydrogen gas adopt a top-feed and bottom-discharge method.

3. The method according to claim 1, characterized in that, The initial boiling point of the wax oil raw material is 200℃~350℃, and the dry point is 500℃~600℃, preferably 530℃~590℃; the nitrogen content is below 2500μg / g, preferably 500μg / g~2000μg / g.

4. The method according to claim 1, characterized in that, The operating conditions of the hydrorefining reactor are as follows: reaction temperature 300℃~420℃, preferably 310℃~390℃; reactor inlet pressure 6MPa~20MPa, preferably 8MPa~18MPa; volume hourly space velocity 0.5h⁻¹. -1 ~3.0h -1 0.6h is preferred -1 ~2.5h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–1200, preferably 500–1100.

5. The method according to claim 1, characterized in that, The hydrorefining catalyst packed in the hydrorefining reactor and the post-hydrorefining catalyst packed in the hydrocracking reactor are hydrocracking pretreatment catalysts; preferably, the hydrorefining catalyst is a Mo-Ni combination of metals with a specific surface area ≥160 m². 2 / g, pore volume ≥0.3mL / g; preferably, the post-hydrogenation refining catalyst is a Mo-Co combination of metals with a specific surface area ≥160m². 2 / g, pore volume ≥0.3mL / g.

6. The method according to claim 1, characterized in that, The operating conditions of the hydrocracking catalyst bed in the hydrocracking reactor in step (2) are as follows: reaction temperature is 350℃~388℃, preferably 365℃~376℃; reactor inlet pressure is 12MPa~20MPa, preferably 15MPa~17MPa; volume hourly space velocity is 0.5h. -1 ~5.0h -1 0.6h is preferred -1 ~3.0h -1 The hydrogen-to-oil volume ratio at the reactor inlet is 400–2000, preferably 500–1100.

7. The method according to any one of claims 1, 4-6, characterized in that, The operating conditions for the hydrorefining catalyst bed after the hydrocracking reactor in step (2) are as follows: the reaction temperature is 360℃~435℃, preferably 375℃~430℃; the volume hourly space velocity of the hydrocracking bed products is 10h. -1 ~25h -1 12h preferred -1 ~20h -1 The hydrogen-to-oil volume ratio is 400–2000, preferably 500–1100, and the reactor inlet pressure is 6 MPa–20 MPa, preferably 8 MPa–18 MPa.

8. The method according to claim 1, characterized in that, The hydrocracking catalyst comprises a cracking component and a hydrogenation component; the cracking component comprises amorphous silica-alumina and / or molecular sieves, such as at least one of Y-type, β-type or USY molecular sieves; the hydrogenation component is selected from at least one of metals, metal oxides or metal sulfides of Group VIB, Group VIIB or Group VIII, and the hydrogenation metal is more preferably one or more of iron, chromium, molybdenum, tungsten, cobalt and nickel; Preferably, based on the weight of the catalyst, the content of the hydrogenation component, calculated as oxide, is 28% to 35%, more preferably 25% to 31%, and the content of molecular sieve is 26% to 40%, more preferably 28% to 36%.

9. The method according to claim 1, characterized in that, The material P is selected from one or more of phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, and aromatic esters of C17-C22, and is further selected from one or more of phenyl dodecanoate, diphenyl m-phthalate, phenyl phthalate, benzo[anthracene]-3-ol, cinnamyl phenylacetate, phenylphenone, and phenolnaphthalene.

10. The method according to claim 1 or 9, characterized in that, Compared to the post-hydrocracking catalyst, the volume hourly space velocity of the material P accounts for 28% to 72% of the total volume hourly space velocity of the hydrocracking bed products and the material P, and is more preferably 30% to 60%.

11. The method according to claim 1, characterized in that, After the hydrocracking bed product flows through the post-hydrorefining catalyst, the retention rate of C18-C20 bicyclic compounds in the post-refined product is above 80 wt%, and more preferably 82 wt% to 97 wt%.

12. The method according to claim 1, characterized in that, The tail oil product obtained from the fractionation system is recycled to the inlet of the hydrorefining reactor.

13. The method according to claim 1, characterized in that, An air-cooling device is installed before the fractionation of the obtained product. The air-cooling device is injected with water so that material P in the product is carried out of the reaction system by the aqueous phase. The amount of water injected is 2 to 30 times the mass flow rate of material P, preferably 3 to 9 times the mass flow rate of material P.

Images