A hydrocracking process for producing jet fuel

Abstract

The application discloses a kind of production of marine coal hydrocracking method.The method uses the hydrogenation refining reactor and the hydrogenation cracking reactor of series connection, including the following steps: wax oil raw material is first carried out hydrogenation refining in hydrogenation refining reactor, the obtained hydrogenation refining stream enters hydrogenation cracking reactor, the obtained product is separated and fractionated, to obtain light naphtha, heavy naphtha, marine coal, diesel and tail oil fraction;Wherein along the liquid phase material flow direction, hydrogenation cracking catalyst bed and post-hydrogenation refining catalyst bed are sequentially arranged in hydrogenation cracking reactor;Material P is introduced between hydrogenation cracking catalyst bed and post-hydrogenation refining catalyst bed;Air cooling device is arranged before the obtained product is fractionated, wherein the air cooling device is water injection, so that material P in product is taken out of reaction system by water phase.The method can improve the stability of marine coal product while improving the yield of marine coal product in hydrogenation cracking device.

Description

Technical Field

[0001] This invention relates to the field of hydrocracking technology, and more specifically to a hydrocracking method for producing jet fuel. Background Technology

[0002] In recent years, the demand for refined oil products has undergone significant changes, with diesel and gasoline demand gradually declining, while the demand for jet fuel has grown rapidly. Hydrocracking can convert heavy feedstock into jet fuel. A conventional hydrocracking process for producing jet fuel involves sequentially feeding wax oil feedstock and hydrogen into a hydrorefining reactor and a hydrocracking reactor. The resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, diesel, and tail oil fractions. Currently, to improve jet fuel yield, hydrocracking units typically increase the reaction temperature. However, with increased reaction temperature, the stability of the resulting jet fuel deteriorates. Therefore, developing technologies that can simultaneously increase jet fuel yield and improve product stability is of significant practical importance.

[0003] CN109266390B discloses a method for hydrocracking to maximize jet fuel yield. The method includes the following steps: S1. Feedstock oil and fresh hydrogen are hydrorefined in a first reactor and then enter a high-pressure separator; S2. The liquid stream from the high-pressure separator sequentially enters a low-pressure separator and a fractionation tower, where naphtha and jet fuel fractions are separated; S3. The gaseous product from the high-pressure separator is compressed and then combined with the bottom material from the fractionation tower into a second reactor for hydrocracking; S4. The effluent from the second reactor is recycled back to the first reactor. This method places the fractionation tower between the hydrorefining and hydrocracking reactors to avoid over-cracking that could affect jet fuel yield, while simultaneously saturating the cracked jet fuel fractions with aromatics to improve their properties. However, the effluent from the second reactor is recycled to the first reactor for joint hydrorefining. The aromatics in the feedstock are all polycyclic aromatic hydrocarbons, which have high content and large adsorption energy, preferentially occupying the active sites of the hydrorefining catalyst. In contrast, the aromatics in the effluent from the second reactor are monocyclic aromatic hydrocarbons, which have low content and low adsorption energy, making it difficult for them to achieve hydrogenation saturation at the active sites of the hydrorefining catalyst. Therefore, this method is not effective in improving the quality of jet fuel.

[0004] CN108003927B discloses a hydrocracking method for producing jet fuel. The method includes: reacting feedstock oil sequentially through a hydrorefining reactor and a hydrocracking reactor in the presence of hydrogen to obtain hydrocracking effluent; then introducing the hydrocracking effluent into a separation unit for sequential gas-liquid separation and fractionation to obtain light naphtha fraction, heavy naphtha fraction, jet fuel fraction, middle distillate oil, and tail oil fraction; circulating all the middle distillate oil after the first catalyst bed of the hydrocracking reactor; and circulating at least 60% by weight of the tail oil fraction to undergo hydrorefining and hydrocracking together with the feedstock oil. This method only focuses on the smoke point properties of the jet fuel components obtained from the hydrocracking reactor. However, the jet fuel components have not undergone a hydrosaturation process, and contain a small amount of unsaturated hydrocarbon components, which can lead to a higher iodine value and increased instability, thus affecting the quality of the jet fuel product. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a hydrocracking method for producing jet fuel. This method improves the jet fuel product yield and stability within the hydrocracking unit.

[0006] This invention provides a hydrocracking method for producing jet fuel, wherein a hydrorefining reactor and a hydrocracking reactor are arranged in series, and the method includes the following steps:

[0007] The wax oil feedstock is first hydrorefined in a hydrorefining reactor, and the resulting hydrorefined stream enters a hydrocracking reactor. The resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, diesel, and tail oil fractions. Along the liquid phase stream direction, a hydrocracking catalyst bed and a post-hydrorefining catalyst bed are sequentially arranged in the hydrocracking reactor. Material P is introduced between the hydrocracking catalyst bed and the post-hydrorefining catalyst bed. Material P is one or more of the following C12-C16 compounds: phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, olefin alcohols, olefin aldehydes, alkynyl alcohols, and alkynyl aldehydes. 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.

[0008] In the method of this invention, both the hydrorefining reactor and the hydrocracking reactor are fixed-bed reactors.

[0009] 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.

[0010] 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 oil (VGO) and deasphalted oil (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.

[0011] In the method of this invention, the operating conditions of the hydrorefining reactor are as follows: reaction temperature is 300℃~420℃, preferably 310℃~390℃; reactor inlet pressure is 6MPa~20MPa, preferably 8MPa~18MPa; liquid 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.

[0012] In the method of this invention, the hydrorefining catalyst packed in the hydrorefining reactor and the post-hydrorefining catalyst packed 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 catalyst for post-hydrogenation refining is a Mo-Co metal 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 hydrorefining reaction is a process of removing impurities such as hydrodesulfurization, denitrification, and aromatic saturation. The hydrorefining catalyst and the post-hydrorefining catalyst can be the same or different.

[0013] In the method of this invention, the operating conditions of the hydrocracking catalyst bed in the hydrocracking reactor are as follows: reaction temperature is 350℃~390℃, preferably 360℃~380℃; reactor inlet pressure is 13MPa~20MPa, preferably 17MPa~19MPa; 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.

[0014] In the method of this invention, the operating conditions of the post-hydrocracking catalyst bed in the hydrocracking reactor 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. -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. Generally, the reaction temperature of the post-hydrogenation refining catalyst bed is 390℃–430℃ during the later stages of operation.

[0015] In the method of this invention, the hydrocracking catalyst is a conventional hydrocracking catalyst used for producing jet fuel. The hydrocracking catalyst comprises a cracking component and a hydrogenation component, and may also include a binder. The cracking component typically comprises at least one amorphous silica-alumina and / or molecular sieve, 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, comprises 15%–27%, preferably 18%–26%, the molecular sieve content comprises 20%–35%, preferably 22%–30%, and the remainder is amorphous silica-alumina and / or binder components. Conventional hydrocracking catalysts can be selected from various existing commercial catalysts, such as FC-76, FC-75, and FC-86 catalysts developed by FRIPP. Specific hydrocracking catalysts can also be prepared as needed, based on common knowledge in the field.

[0016] In the method of this invention, the material P is selected from one or more of the following C12-C16 compounds: phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, olefin alcohols, olefin aldehydes, alkynyl alcohols, and alkynyl aldehydes. It is further selected from one or more of the following: succinate, quercetin, galangin, kaempferol, hexadecenol, (E)-11-tetradecenal, dodecadec-11-en-2-one, and (Z,Z)-11,13-hexadecadienal.

[0017] In the method of the present invention, preferably, the volume hourly space velocity of the material P relative to the post-hydrorefining catalyst is 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.

[0018] In the method of the present invention, preferably, the diesel product obtained from the fractionation system is recycled to the inlet of the hydrocracking reactor or between the catalyst beds of the hydrocracking reactor, and / or, the tail oil product is recycled to the inlet of the hydrorefining reactor.

[0019] The inventors discovered that the main reason for the poor stability of jet fuel produced by hydrocracking units is the dehydrogenation reaction of alkanes and alkylcycloalkanes in the post-refining catalyst reaction zone, generating unsaturated carbon-carbon double or triple bonds. Effectively retaining these alkanes and alkylcycloalkanes would significantly improve the stability of the jet fuel. Further research revealed that material P will react at relatively low space velocities (1.0–2.5 h⁻¹). -1The hydrodeoxygenation reaction is carried out at relatively low temperatures (260–300 °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 reaction environments with high temperatures (360℃~435℃). Therefore, introducing material P before post-hydrogenation refining in the hydrocracking reactor can inhibit the dehydrogenation reaction of alkanes and alkylcycloalkanes in the material during post-refining, which helps to efficiently retain alkanes and alkylcycloalkanes. 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 jet fuel, but also ensure that the stability of jet fuel is effectively improved, so that it can be shipped as a high-quality jet fuel product.

[0020] Further research by the inventors revealed that the content of C13-C15 alkylcycloalkanes in the hydrocracking catalyst bed products changes before and after passing through the post-hydrorefining catalyst bed. When the C13-C15 alkylcycloalkanes undergo dehydrogenation reactions due to contact with the post-hydrorefining catalyst, resulting in a retention rate below 90%, it significantly affects the stability of jet fuel products. Therefore, feedstock P is added to inhibit the dehydrogenation reaction of C13-C15 alkylcycloalkanes. However, since there is a chemical reaction equilibrium between feedstock P, hydrocracking bed products, and post-hydrorefining catalyst, the dehydrogenation reaction of C13-C15 alkylcycloalkanes cannot be completely prevented. It is preferable to control a certain retention rate.

[0021] In the method of this invention, preferably, after the hydrocracking bed product flows through the post-hydrocracking catalyst, the C13-C15 alkylcycloalkanes retention rate in the obtained post-refined product is above 90 wt%, more preferably 92 wt% to 97 wt%. Wherein, the C13-C15 alkylcycloalkanes retention rate = (C13-C15 alkylcycloalkanes concentration in the post-refined product / C13-C15 alkylcycloalkanes concentration in the hydrocracking bed product) * 100%.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 120-180℃, preferably 145-150℃; the initial boiling point of jet fuel is 140-200℃, preferably 145-185℃, and the final boiling point is 220-270℃, preferably 225-260℃; the initial boiling point of diesel fuel is 240-270℃, preferably 245-265℃, and the final boiling point is 330-380℃, preferably 340-375℃; and the initial boiling point of tail oil is 350-390℃, preferably 370-385℃.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (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;

[0028] (2) In the method of the present invention, the stability problem of aviation kerosene is specifically improved by introducing material P, without causing changes in product distribution and other product properties;

[0029] (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 jet fuel components will not have any impurities. The process is energy-saving and efficient.

[0030] (4) The method of the present invention has strong applicability and can improve the stability of jet fuel for any hydrocracking catalyst and process conditions. The adjustment method is flexible. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the process of the present invention;

[0032] The annotations in the attached figures are explained as follows:

[0033] 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 feedstock, 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-Fractioning system, 20-Naphtha, 21-Jet fuel, 22-Diesel, 23-Tail oil. Detailed Implementation

[0034] The method of the present invention will be described in more detail below with reference to specific embodiments and comparative examples.

[0035] This invention provides a hydrocracking method for producing jet fuel, such as... Figure 1 As shown, it includes:

[0036] 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 then enters the fractionation system 19 for further separation, yielding naphtha 20, jet fuel 21, diesel fuel 22, and tail oil 23. Diesel fuel 22 can be recycled to the inlet of the hydrocracking reactor 4 or to the catalyst bed, while tail oil 23 can be recycled to the inlet of the hydrorefining reactor.

[0037] 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 148°C, the distillation range of jet fuel is 148 to 249°C, the distillation range of diesel is 249 to 370°C, and the tail oil is the fraction above 370°C.

[0038] 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.

[0039] Table 1 Main Properties of Crude Oil

[0040] 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

[0041] Table 2 Main properties of the catalyst

[0042]

[0043]

[0044] Example 1

[0045] Adopting such Figure 1This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (filled in four hydrocracking catalyst beds, sequentially named first, second, third, and fourth beds along the feed direction), and post-hydrorefining catalyst A is used. Feed material P uses (E)-11-tetradecenoal. All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled between the second and third beds of the hydrocracking reactor. The single-pass conversion rate is controlled at approximately 70%, and jet fuel product properties are sampled and analyzed.

[0046] Example 2

[0047] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (filled in four hydrocracking catalyst beds, sequentially arranged along the feed direction as the first, second, third, and fourth beds), and post-hydrorefining catalyst C is used. Feedstock P consists of galangin, kaempferol, and hexadecenol (with a mass ratio of 0.5:1:2). All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled between the second and third beds of the hydrocracking reactor, controlling the single-pass conversion rate to approximately 70%. Samples are taken and analyzed to determine the properties of the jet fuel.

[0048] Example 3

[0049] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (filled in four hydrocracking catalyst beds, sequentially arranged along the feed direction as the first, second, third, and fourth beds), and post-hydrorefining catalyst C is used. Feedstock P consists of succinate, succinate, (Z,Z)-11,13-hexadecadienal, and dodecano-11-en-2-one (where the mass ratio of succinate, succinate, (Z,Z)-11,13-hexadecadienal, and dodecano-11-en-2-one is 3:1.5:1:0.8). All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled to the inlet of the hydrocracking reactor, controlling the single-pass conversion rate to approximately 60%. Samples are taken and analyzed to determine the properties of the jet fuel.

[0050] Comparative Example 1

[0051] 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.

[0052] A conventional single-stage series process flow is adopted. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (packed in four hydrocracking catalyst beds, sequentially arranged along the stream direction as bed 1, bed 2, bed 3, and bed 4), and post-hydrorefining catalyst A is used. All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled between the second and third beds of the hydrocracking reactor, controlling the single-pass conversion rate to approximately 70%. Jet kerosene product properties are sampled and analyzed.

[0053] Comparative Example 2

[0054] 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.

[0055] A conventional single-stage series process flow is adopted. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (filled in four hydrocracking catalyst beds, sequentially arranged along the stream direction as the first, second, third, and fourth beds), and post-hydrorefining catalyst C is used. All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled to the inlet of the hydrocracking reactor, controlling the single-pass conversion rate at approximately 60%. Jet kerosene product properties are sampled and analyzed.

[0056] Comparative Example 3

[0057] The difference compared to Example 3 is that the material P is different.

[0058] Adopting such Figure 1 This is a series process flow. Hydrorefining catalyst A is used, hydrocracking catalyst B is used (filled in four hydrocracking catalyst beds, sequentially arranged along the feed direction as the first, second, third, and fourth beds), and post-hydrorefining catalyst C is used. Feedstock P consists of propyne aldehyde, pentenal, and 3-buten-1-ol (mass ratio of propyne aldehyde, pentenal, and 3-buten-1-ol is 1:2.5:0.8). All tail oil is recycled to the inlet of the hydrorefining reactor, and diesel fuel is recycled to the inlet of the hydrocracking reactor, controlling the single-pass conversion rate to approximately 60%. Samples are taken to analyze the properties of the jet fuel.

[0059] The effects of the above embodiments and comparative examples are compared in Table 3.

[0060] Table 3. Reaction conditions and results for each embodiment and comparative example.

[0061]

[0062]

Claims

1. A hydrocracking method for producing jet fuel, wherein, The hydrorefining reactor and the hydrocracking reactor, arranged in series, include the following steps: The wax oil feedstock is first hydrorefined in a hydrorefining reactor, and the resulting hydrorefined stream enters a hydrocracking reactor. The resulting products are separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, diesel, and tail oil fractions. Along the liquid phase stream direction, a hydrocracking catalyst bed and a post-hydrorefining catalyst bed are sequentially arranged in the hydrocracking reactor. Material P is introduced between the hydrocracking catalyst bed and the post-hydrorefining catalyst bed. Material P is one or more of the following C12-C16 compounds: phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, olefin alcohols, olefin aldehydes, alkynyl alcohols, and alkynyl aldehydes. 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 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 is 300℃~420℃, preferably 310℃~390℃; reactor inlet pressure is 6MPa~20MPa, preferably 8MPa~18MPa; liquid 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.

5. The method according to claim 1 or 4, 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 metal combination with a specific surface area of ​​≥160 m². 2 / g, pore volume ≥ 0.3mL / g; Preferably, the catalyst for post-hydrogenation refining is a Mo-Co metal combination with a specific surface area of ​​≥160 m². 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 are as follows: reaction temperature 350℃~390℃, preferably 360℃~380℃; reactor inlet pressure 13MPa~20MPa, preferably 17MPa~19MPa; volume hourly space velocity 0.5h⁻¹. -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. And / or, the operating conditions of the post-hydrocracking catalyst bed in the hydrocracking reactor are as follows: reaction temperature of 360℃~435℃, preferably 375℃~430℃; and volume hourly space velocity of the hydrocracking bed products of 10 h⁻¹. -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.

7. The method according to claim 1 or 6, 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 15% to 27%, more preferably 18% to 26%, and the content of molecular sieve is 20% to 35%, more preferably 22% to 30%.

8. The method according to claim 1, characterized in that, The material P is selected from one or more of the following C12-C16 compounds: phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, olefin alcohols, olefin aldehydes, alkynyl alcohols, and alkynyl aldehydes. It is further selected from one or more of the following: flavonoids, galangin, kaempferol, hexadecenol, (E)-11-tetradecenal, dodecadec-11-en-2-one, and (Z,Z)-11,13-hexadecadienal.

9. The method according to claim 1 or 8, characterized in that, Compared 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, and is more preferably 30% to 60%.

10. The method according to claim 1, characterized in that, After the hydrocracking bed product flows through the post-hydrorefining catalyst, the C13-C15 alkylcycloalkanes in the resulting post-refined product retain more than 90 wt%, and more preferably 92 wt% to 97 wt%.

11. The method according to claim 1, characterized in that, The diesel product obtained from the fractionation system is recycled to the inlet of the hydrocracking reactor or between the catalyst beds of the hydrocracking reactor, and / or the tail oil product is recycled to the inlet of the hydrorefining reactor.

12. 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.

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