Method for preparing lubricant base oil from Fischer-Tropsch hydrogenation tail oil

Abstract

The invention relates to the technical field of coal chemical industry, and discloses a method for preparing lubricant base oil from Fischer-Tropsch hydrogenation tail oil. The method comprises the following steps: carrying out a first-stage reaction, a second-stage reaction and a third-stage reaction on the Fischer-Tropsch hydrogenation tail oil and hydrogen in sequence, and rectifying the reacted material, the first-stage reaction is carried out in the presence of a first hydroisomerization catalyst, and the second-stage reaction is carried out in the presence of a second hydroisomerization catalyst; the total acid amount of the first hydroisomerization catalyst is larger than that of the second hydroisomerization catalyst, and the specific surface area and pore volume of the first hydroisomerization catalyst are smaller than those of the second hydroisomerization catalyst; the temperature of the first-stage reaction is less than or equal to the temperature of the second-stage reaction, and the hydrogen partial pressure of the first-stage reaction is less than or equal to the hydrogen partial pressure of the second-stage reaction. According to the method, the Fischer-Tropsch hydrogenation tail oil full fraction can be applied, and it can be guaranteed that the prepared lubricating oil base oil has excellent quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal chemical industry, and particularly relates to a method for preparing lubricating oil base oil by using Fischer-Tropsch hydrogenation tail oil. BACKGROUND

[0002] The coal indirect liquefaction process is a process of generating oil products and chemicals through gasification, shift conversion, purification and Fischer-Tropsch synthesis of coal. The intermediate product of Fischer-Tropsch synthesis is rich in olefins, and after hydrogenation saturation, the main component is linear alkanes. The saturated hydrocarbon content in Fischer-Tropsch hydrogenation tail oil is high (≥90%), the distillation range is wide, and part of the isomeric hydrocarbons exist, which is suitable for producing lubricating oil base oil products with different viscosities.

[0003] Chinese patent CN112111300A discloses a method for preparing lubricating oil base oil from Fischer-Tropsch hydrogenation cracking tail oil, which comprises: (1) cutting and separating the Fischer-Tropsch hydrogenation cracking tail oil to obtain light components and heavy components; (2) carrying out first contact reaction of the heavy components with a first hydrogenation isomerization catalyst to obtain material i; (3) mixing the light components with material i and then carrying out second contact reaction of the mixture with a second hydrogenation isomerization catalyst to obtain material ii; (4) carrying out contact reaction of material ii with a hydrogenation refining catalyst to obtain material iii, and then fractionating material iii. The reaction conditions of the method are mild, the yield of lubricating oil base oil is high, the viscosity index of the obtained lubricating oil base oil is high, and the pour point is low. Chinese patent CN103289738A discloses a method for producing high-grade lubricating oil base oil from hydrogenation cracking tail oil, which comprises: after vacuum distillation of the hydrogenation cracking tail oil, cutting and separating it into two fractions less than 430℃ and greater than 430℃, and then carrying out hydrogenation isomerization dewaxing reaction at high pressure and high temperature by using switching feeding mode or independent feeding mode, and the catalyst is a noble metal supported on an alumina carrier. The products after reaction are cut and separated to obtain lubricating oil base oil. However, in these methods, Fischer-Tropsch hydrogenation cracking tail oil is used as the raw material for preparation, and it is necessary to first carry out fractionation cutting of the Fischer-Tropsch hydrogenation cracking tail oil, and then use the obtained fraction as the raw material for preparation, which increases the energy consumption for preparing the base oil, and part of the heavy component raw material in the Fischer-Tropsch hydrogenation cracking tail oil is lost after fractionation cutting, which makes it impossible to produce base oil products with different viscosities, and it is difficult to solve the technical problem of high pour point and cloud point of the base oil by using Fischer-Tropsch hydrogenation cracking tail oil as the raw material.

[0004] Due to the high content of isomeric hydrocarbons in the Fischer-Tropsch hydrogenation tail oil, the Fischer-Tropsch hydrogenation tail oil has a high condensation point, and it is more difficult to prepare a low pour point base oil lubricant using the Fischer-Tropsch hydrogenation tail oil, so the technology of using the Fischer-Tropsch hydrogenation tail oil as a raw material to prepare base oil is not common at present, and when the Fischer-Tropsch hydrogenation tail oil is used to prepare base oil, the Fischer-Tropsch hydrogenation tail oil is usually first subjected to rectification cutting, and there are problems such as waste of raw materials and inability to produce base oil products with different viscosities. SUMMARY

[0005] The purpose of the present application is to overcome the problems in the prior art that the Fischer-Tropsch hydrogenation tail oil is wasted to some extent in the process of preparing base oil lubricant using the Fischer-Tropsch hydrogenation tail oil, and different viscosity base oil products cannot be produced, and to provide a method for preparing base oil lubricant using Fischer-Tropsch hydrogenation tail oil. The method can apply the whole fraction of the Fischer-Tropsch hydrogenation tail oil, and can ensure that the prepared base oil lubricant has excellent quality.

[0006] In order to achieve the above-mentioned purpose, one aspect of the present application provides a method for preparing base oil lubricant using Fischer-Tropsch hydrogenation tail oil, which comprises: sequentially subjecting the Fischer-Tropsch hydrogenation tail oil and hydrogen to one-stage reaction, two-stage reaction and three-stage reaction, and then subjecting the reacted material to rectification.

[0007] The one-stage reaction is carried out in the presence of a first hydrogen isomerization catalyst, and the two-stage reaction is carried out in the presence of a second hydrogen isomerization catalyst; the total acid amount of the first hydrogen isomerization catalyst is greater than that of the second hydrogen isomerization catalyst, and the specific surface area and pore volume of the first hydrogen isomerization catalyst are smaller than those of the second hydrogen isomerization catalyst.

[0008] The first hydrogen isomerization catalyst contains a first carrier and a first noble metal component supported on the first carrier, and the second hydrogen isomerization catalyst contains a second carrier and a second noble metal component supported on the second carrier; the first carrier comprises a first molecular sieve and a first binder, and the second carrier comprises a second molecular sieve and a second binder; the first molecular sieve and the second molecular sieve are each selected from one or more than two of ZSM-48, ZSM-22, ZSM-23 and SAPO-11; the weak acid amount of the first hydrogen isomerization catalyst and the second hydrogen isomerization catalyst is 0.1-0.35 mmol / g, and the medium strong acid amount is 0.05-0.3 mmol / g.

[0009] The conditions of the one-stage reaction include: temperature 300-350℃, hydrogen partial pressure 2-10 MPa, volume space velocity 0.3-2h -1 ;

[0010] The conditions of the two-stage reaction include: temperature of 300-350℃, hydrogen partial pressure of 2-10 MPa, volume space velocity of 0.3-2 h -1 ; the temperature of the one-stage reaction is ≤ the temperature of the two-stage reaction, and the hydrogen partial pressure of the one-stage reaction is ≤ the hydrogen partial pressure of the two-stage reaction.

[0011] Preferably, the specific surface area of the second hydroisomerization catalyst is 20-60 m 2 / g larger than the specific surface area of the first hydroisomerization catalyst, and the pore volume of the second hydroisomerization catalyst is 0.03-0.18 cm 3 / g larger than the pore volume of the first hydroisomerization catalyst.

[0012] Preferably, the specific surface area of the first and second hydroisomerization catalysts is ≥ 150 m 2 / g, and the pore volume of the first and second hydroisomerization catalysts is ≤ 0.5 cm 3 / g.

[0013] Preferably, the specific surface area of the first hydroisomerization catalyst is 150-250 m 2 / g, and the specific surface area of the second hydroisomerization catalyst is 180-250 m 2 / g.

[0014] Preferably, the pore volume of the first hydroisomerization catalyst is 0.25-0.5 cm 3 / g, and the pore volume of the second hydroisomerization catalyst is 0.3-0.5 cm 3 / g.

[0015] Preferably, the first and second noble metal components are each Pt and / or Pd.

[0016] Preferably, the content of the first noble metal component is 3-5 parts by weight relative to 100 parts by weight of the first carrier.

[0017] Preferably, the content of the second noble metal component is 3-5 parts by weight relative to 100 parts by weight of the second carrier.

[0018] Preferably, the temperature of the one-stage reaction is 5-20℃ lower than the temperature of the two-stage reaction.

[0019] Preferably, the temperature of the one-stage reaction is 305-330℃, and the temperature of the two-stage reaction is 310-340℃.

[0020] Preferably, the hydrogen partial pressure of the one-stage reaction is 0.2-4 MPa lower than the hydrogen partial pressure of the two-stage reaction.

[0021] Preferably, the hydrogen partial pressure in the first stage reaction is 3-5 MPa, and the hydrogen partial pressure in the second stage reaction is 5-8 MPa.

[0022] Preferably, the hydrogen oil volume ratio in the first stage reaction is 200-2000:1.

[0023] Preferably, the hydrogen oil volume ratio in the second stage reaction is 200-2000:1.

[0024] Preferably, the third stage reaction is carried out in the presence of a third hydrogenation catalyst.

[0025] Preferably, the third hydrogenation catalyst contains a carrier and an active metal component, the carrier is large-pore alumina and / or silica alumina, and the metal in the active metal component is selected from one or more than two of Pt, Pd, Ni and W.

[0026] Preferably, the conditions of the third stage reaction include: the temperature is 200-280℃, the volume space velocity is 0.2-2h -1 , the hydrogen oil volume ratio is 200-2000:1, and the hydrogen partial pressure is 2-10 MPa.

[0027] Preferably, the silica alumina ratio of the first molecular sieve is 50-150, and the silica alumina ratio of the second molecular sieve is 0.5-150.

[0028] Preferably, the first molecular sieve is one or more than two of ZSM-48, ZSM-22 and ZSM-23, and the second molecular sieve is one or more than two of ZSM-48, SAPO-11 and ZSM-23.

[0029] Preferably, the silica alumina ratio of the ZSM-22 is 60-90, the silica alumina ratio of the ZSM-23 is 100-140, the silica alumina ratio of the ZSM-48 is 100-150, and the silica alumina ratio of the SAPO-11 is 0.5-1.

[0030] Preferably, in the first hydrogenation isomerization catalyst, the weight ratio of the first binder to the first molecular sieve is 0.3-0.8:1.

[0031] Preferably, in the second hydrogenation isomerization catalyst, the weight ratio of the second binder to the second molecular sieve is 0.28-0.7:1.

[0032] Preferably, in the material after the first stage reaction, the mass content corresponding to the distillation temperature of 350℃ is ≤10%.

[0033] In order to further avoid waste caused by the distillation cutting pretreatment process on the Fischer-Tropsch hydrogenation tail oil when the Fischer-Tropsch hydrogenation tail oil is used to prepare a lubricating oil base oil, the Fischer-Tropsch hydrogenation tail oil is directly subjected to three-stage hydroisomerization, the relationship between the composition, the acid amount, the specific surface area and the pore volume of the catalysts used in the first-stage reaction process and the second-stage reaction process is regulated, and the reaction conditions used in the first-stage reaction and the second-stage reaction are limited, the two-stage hydroisomerization processes are coupled, the acid strength of the first hydroisomerization catalyst is limited to be strong, the first-stage reaction is limited to use a lower hydrogen partial pressure and a lower reaction temperature compared with the second-stage reaction, the heavy components are isomerized in the first-stage reaction while accompanied by a small amount of cracking side reactions, the isomerization and condensation difficulty of the heavy components is reduced, the acid strength of the second hydroisomerization catalyst is limited to be weak, the cracking side reactions are further inhibited, and the base oil selectivity is improved, so that the yield of the base oil product is improved, the degree of hydroisomerization of the Fischer-Tropsch hydrogenation tail oil in the first-stage reaction process is regulated to be low, the degree of hydroisomerization of the Fischer-Tropsch hydrogenation tail oil in the second-stage reaction process is regulated to be high, and the olefins contained in the Fischer-Tropsch tail oil are hydrogenated through the three-stage reaction, so that the product stability of the Fischer-Tropsch tail oil after isomerization is ensured. The lubricating oil base oil prepared by the method has low pour point and different viscosity, high product yield, and excellent product quality.

[0034] In addition, the method has a simple complete process flow and mild operation conditions, the base oil product has the characteristics of high viscosity index, low pour point, high yield, and the like, and industrialized production is more easily realized. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 FIG. 1 is a process flow diagram of the method for preparing a lubricating oil base oil from a Fischer-Tropsch hydrogenation tail oil according to the present application. DETAILED DESCRIPTION

[0036] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0037] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and are understood to be encompassed by the range or value they approximate. For ranges, the endpoints are included within the range unless specifically stated otherwise. For example, a range of "1 to 10" is intended to include "1 to 10" and any value or range of values within this range, such as 1.1 to 10, 1.2 to 10, 1.3 to 10, etc.

[0038] In the prior art, when preparing lubricating oil base oil by using Fischer-Tropsch hydrogenation tail oil, in order to enrich the material for performing hydroisomerization in the Fischer-Tropsch hydrogenation tail oil, facilitate the subsequent hydroisomerization reaction and avoid the influence of impurity components contained in the Fischer-Tropsch hydrogenation tail oil on the product quality, the Fischer-Tropsch hydrogenation tail oil is usually subjected to rectification cutting, and the obtained fraction is used as a raw material to prepare lubricating oil base oil. However, the Fischer-Tropsch hydrogenation tail oil rectification cutting process will cause a loss of a part of alkanes, thereby causing a waste of the raw material to a certain extent. However, since the carbon atom number distribution of the saturated hydrocarbons contained in the Fischer-Tropsch hydrogenation tail oil is wide and the components are complex, directly performing hydroisomerization on the Fischer-Tropsch hydrogenation tail oil will seriously affect the hydroisomerization degree and the reaction rate, thereby causing a reduction in product yield and a reduction in product quality, a reduction in the yield of the prepared lubricating oil base oil and an increase in process cost.

[0039] Therefore, in order to reduce the waste of Fischer-Tropsch hydrogenation tail oil and ensure the preparation of lubricating oil base oil products with low pour point and different viscosities, the present application provides a method for directly using Fischer-Tropsch hydrogenation tail oil as a raw material to prepare lubricating oil base oil without rectification cutting of the Fischer-Tropsch hydrogenation tail oil. The method directly produces lubricating oil base oil with different viscosities and low pour point by hydroisomerization of the Fischer-Tropsch hydrogenation tail oil, and has high product yield, high yield, excellent quality and further saves the preparation cost. Specifically, the process flow of the method for preparing lubricating oil base oil by using Fischer-Tropsch hydrogenation tail oil is shown in Figure 1 The method comprises: sequentially performing one-stage reaction, two-stage reaction and three-stage reaction on the Fischer-Tropsch hydrogenation tail oil and hydrogen, and then performing rectification on the reacted material.

[0040] In the method, the distillation range of the Fischer-Tropsch hydrogenation tail oil is 350-740 DEG C, and the content of saturated hydrocarbons is greater than or equal to 90%. The Fischer-Tropsch hydrogenation tail oil is first subjected to one-stage hydroisomerization reaction to realize shallow isomerization of the raw material, so as to reduce the difficulty of subsequent hydroisomerization and prevent the distillation range of the raw material from being too wide during the two-stage reaction. Then, the material after the one-stage reaction is subjected to two-stage hydroisomerization reaction, so as to deeply isomerize the heavy components in the Fischer-Tropsch hydrogenation tail oil and realize dewaxing treatment of the Fischer-Tropsch hydrogenation tail oil. Then, the material after the two-stage reaction is subjected to three-stage hydrogenation reaction to convert the unsaturated olefins contained in the Fischer-Tropsch hydrogenation tail oil into saturated hydrocarbons, and then rectification is performed to prepare lubricating oil base oil products.

[0041] Specifically, the first stage reaction is carried out in the presence of a first hydroisomerization catalyst, and the second stage reaction is carried out in the presence of a second hydroisomerization catalyst. In the method of the present application, by limiting the composition, the acid amount relationship, and the specific surface area and pore volume of the first hydroisomerization catalyst and the second hydroisomerization catalyst, the degree of isomerization of the Fischer-Tropsch hydroisomerization tail oil in the first stage reaction and the second stage reaction can be controlled, and it is ensured that the impurity elements in the Fischer-Tropsch hydroisomerization tail oil do not affect the quality of the prepared lubricating oil base oil. In a preferred case, the mass content corresponding to the distillation temperature of 350°C in the material after the first stage reaction is ≤10%, for example, it can be 5-10 wt%. By controlling the content of light components (350°C fraction) in the hydroisomerization product after the first stage reaction, the distillation range of the raw material in the second hydroisomerization process in the second stage reaction can be reduced, thereby affecting the pour point and yield of the prepared lubricating oil base oil.

[0042] Specifically, the first hydroisomerization catalyst contains a first carrier and a first noble metal component supported on the first carrier, and the second hydroisomerization catalyst contains a second carrier and a second noble metal component supported on the second carrier, the first carrier comprises a first molecular sieve and a first binder, and the second carrier comprises a second molecular sieve and a second binder; and the first molecular sieve is selected from one or more than two of ZSM-48, ZSM-22, ZSM-23 and SAPO-11; the second molecular sieve is selected from one or more than two of ZSM-48, ZSM-22, ZSM-23 and SAPO-11, it should be noted that the composition of the first molecular sieve and the second molecular sieve can be the same or different, and ZSM-48, ZSM-22, ZSM-23 and SAPO-11 are all commercially available products or can be prepared according to the common method in the art.

[0043] In the method of the present application, the silicon-aluminum ratio of the first molecular sieve is 50-150, and the silicon-aluminum ratio of the second molecular sieve is 0.5-150. There is a direct relationship between the silicon-aluminum ratio of the molecular sieve and its acidity, and by limiting the silicon-aluminum ratio of the first molecular sieve and the second molecular sieve in the present application, the acidity of the first hydroisomerization catalyst and the second hydroisomerization catalyst can be further limited, thereby controlling the catalytic activity of the catalyst used.

[0044] In some preferred embodiments, the first molecular sieve is one or more of ZSM-48, ZSM-22 and ZSM-23, and the second molecular sieve is one or more of ZSM-48, SAPO-11 and ZSM-23. By further limiting the specific component selection of the first molecular sieve and the second molecular sieve, the catalytic activity of the first hydrogen isomerization catalyst and the second hydrogen isomerization catalyst used is further regulated, so as to realize the regulation of the isomerization degree of the Fischer-Tropsch hydrocracking tail oil in different reaction stages.

[0045] In some particularly preferred embodiments, the silicon-aluminum ratio of the ZSM-22 used is further limited to 60-90, the silicon-aluminum ratio of the ZSM-23 is 100-140, the silicon-aluminum ratio of the ZSM-48 is 100-150, and the silicon-aluminum ratio of the SAPO-11 is 0.5-1.

[0046] Specifically, the first noble metal component is the catalytically active component of the first hydrogen isomerization catalyst, and the second noble metal component is the catalytically active component of the second hydrogen isomerization catalyst. In a preferred case, the first noble metal component is Pt and / or Pd, and the content of the first noble metal component in the first hydrogen isomerization catalyst is 0.3-0.5 wt%. The second noble metal component is Pt and / or Pd, and the content of the second noble metal component in the second hydrogen isomerization catalyst is 0.3-0.5 wt%.

[0047] In the method of the present application, the first binder and the second binder are used to bind and shape the molecular sieve, which is more conducive to industrial application. In a preferred case, the weight ratio of the first binder to the first molecular sieve in the first hydrogen isomerization catalyst is 0.3-0.8:1, and the weight ratio of the second binder to the second molecular sieve in the second hydrogen isomerization catalyst is 0.28-0.7:1. In some embodiments, the first binder and the second binder can be alumina.

[0048] In addition, in the method of the present application, the total acid amount of the first hydrogen isomerization catalyst is further limited to be greater than that of the second hydrogen isomerization catalyst, and by further limiting the relationship between the total acid amounts of the two, the isomerization degree of the Fischer-Tropsch hydrocracking tail oil in the two-stage hydrogen isomerization reaction can be further ensured, so as to ensure that the base oil lubricant prepared has a lower pour point and better quality. Specifically, the total acid amount in the present application can be obtained by the NH3-TPD method, and the value of the total acid amount is the integral area of the desorption curve in the NH3-TPD spectrum obtained by testing.

[0049] In some preferred embodiments, to further ensure product quality, the total acid amount of the first hydroisomerization catalyst is greater than that of the second hydroisomerization catalyst. Further preferably, the total acid amount of the first hydroisomerization catalyst is 0.4-0.6 mmol / g, and the total acid amount of the second hydroisomerization catalyst is 0.3-0.5 mmol / g.

[0050] In the manner described in the present application, the weak acid amount of the first hydroisomerization catalyst is 0.1-0.35 mmol / g, and the medium-strong acid amount is 0.05-0.3 mmol / g; the weak acid amount of the second hydroisomerization catalyst is 0.1-0.35 mmol / g, and the medium-strong acid amount is 0.05-0.3 mmol / g. In the present application, on the basis of the relationship between the total acid amount of the first hydroisomerization catalyst and the total acid amount of the second hydroisomerization catalyst, the weak acid amount and the medium-strong acid amount in the first hydroisomerization catalyst and the second hydroisomerization catalyst are further limited, which can further ensure that the influence of the impurity components in the Fischer-Tropsch hydroisomerization tail oil on the quality of the prepared lubricating oil base oil is reduced, and the product yield is improved. It should be noted that the weak acid amount and the medium-strong acid amount described in the present application can be obtained by the NH3-TPD method, the weak acid amount is the integral area corresponding to the NH3-TPD desorption curve of the catalyst at a temperature range of 100-200 ℃, and the medium-strong acid amount is the integral area corresponding to the desorption curve at a temperature range of 200-500 ℃.

[0051] In some preferred embodiments, the weak acid amount of the first hydroisomerization catalyst is higher than that of the second hydroisomerization catalyst, and the medium-strong acid amount of the first hydroisomerization catalyst is higher than that of the second hydroisomerization catalyst. In a particularly preferred case, the weak acid amount of the first hydroisomerization catalyst is 0.01-0.1 mmol / g higher than that of the second hydroisomerization catalyst, preferably 0.01-0.1 mmol / g, more preferably 0.015-0.05 mmol / g; the medium-strong acid amount of the first hydroisomerization catalyst is 0.05-0.15 mmol / g higher than that of the second hydroisomerization catalyst, preferably 0.06-0.13 mmol / g, more preferably 0.07-0.12 mmol / g. In a more preferred case, the weak acid amount of the first hydroisomerization catalyst is 0.23-0.35 mmol / g, and the medium-strong acid amount is 0.15-0.3 mmol / g; the weak acid amount of the second hydroisomerization catalyst is 0.2-0.33 mmol / g, and the medium-strong acid amount is 0.1-0.18 mmol / g.

[0052] In the method described in the present application, on the basis of defining the relationship between the total acid amount, weak acid amount and medium-strong acid amount between the first hydroisomerization catalyst and the second hydroisomerization catalyst, the relationship between the specific surface area and the pore volume between the first hydroisomerization catalyst and the second hydroisomerization catalyst is further defined, the difference in catalytic activity between the first hydroisomerization catalyst and the second hydroisomerization catalyst can be further defined, and by regulating the difference in activity of the two catalysts, the degree of isomerization of the Fischer-Tropsch hydroisomerization tail oil in the one-stage reaction and the two-stage reaction is further regulated, which can further improve the quality and yield of the prepared lubricating oil base oil, and further improve the reaction efficiency. Specifically, the specific surface area of the first hydroisomerization catalyst is less than the specific surface area of the second hydroisomerization catalyst; the pore volume of the first hydroisomerization catalyst is less than the pore volume of the second hydroisomerization catalyst.

[0053] In some preferred embodiments, in order to further improve the product yield, it is further defined that the specific surface area of the second hydroisomerization catalyst is 20-60 m 2 / g larger than the specific surface area of the first hydroisomerization catalyst; the pore volume of the second hydroisomerization catalyst is 0.03-0.1 cm 3 / g larger than the pore volume of the first hydroisomerization catalyst. In a particularly preferred case, the specific surface area of the first hydroisomerization catalyst and the second hydroisomerization catalyst is ≥150 m 2 / g; the pore volume of the first hydroisomerization catalyst and the second hydroisomerization catalyst is ≤0.5 cm 3 / g. In a more preferred case, the specific surface area of the first hydroisomerization catalyst is 150-250 m 2 / g; the specific surface area of the second hydroisomerization catalyst is 180-250 m 2 / g; the pore volume of the first hydroisomerization catalyst is 0.25-0.5 cm 3 / g; the pore volume of the second hydroisomerization catalyst is 0.3-0.5 cm 3 / g.

[0054] In the method of the present application, in addition to the requirement of limiting the grading relationship of the catalysts used in the first-stage reaction and the second-stage reaction, the reaction conditions of the first-stage reaction and the second-stage reaction are further limited. The limited relationship among the components of the catalysts used in the method of the present application, the acid amount, the specific surface area and the pore volume, and the reaction conditions used in the first-stage reaction and the second-stage reaction belong to a mutual matching relationship, and both are indispensable in the method of the present application, and both work together to ensure that the Fischer-Tropsch hydrogenation tail oil can be directly used to prepare the lubricating oil base oil, and ensure that the impurity elements in the Fischer-Tropsch hydrogenation tail oil do not affect the quality of the prepared lubricating oil base oil, and ensure that the prepared product has low pour point, excellent quality, and high yield.

[0055] Specifically, in the method of the present application, the conditions of the first-stage reaction include: the temperature is 300-350℃, the hydrogen partial pressure is 2-10 MPa, and the volume space velocity is 0.3-2 h -1 ; the conditions of the second-stage reaction include: the temperature is 300-350℃, the hydrogen partial pressure is 2-10 MPa, and the volume space velocity is 0.3-2 h -1 . Specifically, the hydrogen partial pressure refers to the partial pressure of hydrogen in the raw material mixed gas.

[0056] In the method of the present application, in order to further ensure the preparation of the lubricating oil base oil with low pour point, the temperature of the first-stage reaction is further limited to be ≤ the temperature of the second-stage reaction, and the hydrogen partial pressure of the first-stage reaction is further limited to be ≤ the hydrogen partial pressure of the second-stage reaction, which ensures that the first-stage reaction is carried out at a lower hydrogen partial pressure and temperature compared with the second-stage reaction, and promotes the isomerization of heavy components in the first-stage reaction accompanied by a small amount of cracking side reaction, thereby reducing the difficulty of isomerization and condensation of heavy components.

[0057] Further preferably, the temperature of the first-stage reaction is 5-20℃ lower than the temperature of the second-stage reaction. In a more preferred case, the temperature of the first-stage reaction is 305-330℃, and the temperature of the second-stage reaction is 315-340℃.

[0058] In some preferred embodiments, in order to further reduce the difficulty of isomerization and condensation of heavy components in the Fischer-Tropsch hydrogenation tail oil and ensure the quality of the prepared product, the hydrogen partial pressure of the first-stage reaction is 0.2-4 MPa lower than the hydrogen partial pressure of the second-stage reaction, preferably 0.2-3 MPa. In a more preferred case, the hydrogen partial pressure of the first-stage reaction is 3-5 MPa, and the hydrogen partial pressure of the second-stage reaction is 5-8 MPa.

[0059] In some embodiments, the volume ratio of hydrogen to oil in the first stage reaction is 200-2000:1, preferably 500-1000:1. In the present application, the hydrogen to oil ratio refers to the volume ratio of hydrogen to oil during the reaction.

[0060] In some embodiments, the volume ratio of hydrogen to oil in the second stage reaction is 200-2000:1, preferably 500-1000:1.

[0061] In the process of the present application, the third stage reaction is used to hydrofinish the unsaturated hydrocarbons contained in the Fischer-Tropsch hydrogenation tail oil with hydrogen, and the third stage reaction is carried out in the presence of a third hydrogenation catalyst. The third hydrogenation catalyst contains a carrier and an active metal component, and the active metal component is supported on the carrier, wherein the carrier is a large-pore alumina and / or silica alumina, preferably a large-pore alumina, and the metal in the active metal component is selected from one or more than one of Pt, Pd, Ni and W, preferably Pt and / or Pd. In some preferred cases, in the third hydrogenation catalyst, the content of the active metal component is 0.3-1 wt%, wherein the active metal component is calculated based on the active metal.

[0062] In some preferred embodiments, the conditions of the third stage reaction include: the temperature is 200-280℃, the volume space velocity is 0.2-2h -1 -1, the volume ratio of hydrogen to oil is 200-200:1, and the hydrogen partial pressure is 2-10 MPa.

[0063] The distillation ranges of the target product prepared by the process of the present application are: naphtha fraction <150℃, aviation kerosene fraction 150-260℃, diesel fraction 260-350℃, and base oil fraction >350℃. The specific process of the distillation can refer to the common techniques in the art.

[0064] In the method described in the present application, the first hydroisomerization catalyst, the second hydroisomerization catalyst and the third hydrogenation catalyst used can be prepared according to the common method in the art (for example, the isometric impregnation method). For example, the preparation method of the first hydroisomerization catalyst can be as follows: the first molecular sieve is mixed with the first binder to form a first carrier, then the first carrier is impregnated in an impregnation solution containing a first noble metal precursor, and then the solid phase obtained by impregnation is calcined to obtain the first hydroisomerization catalyst. For example, the preparation method of the second hydroisomerization catalyst can be as follows: the second molecular sieve is mixed with the second binder to form a second carrier, then the second carrier is impregnated in an impregnation solution containing a second noble metal precursor, and then the solid phase obtained by impregnation is calcined to obtain the second hydroisomerization catalyst. For example, the preparation method of the third hydrogenation catalyst can be as follows: the active metal component precursor is loaded on the carrier by the isometric impregnation method, and then the solid phase obtained by impregnation is calcined to obtain the third hydrogenation catalyst. In the above method, the impregnation can be carried out by the isometric impregnation method, and the temperature of calcination and the conditions of isometric impregnation can all refer to the conventional technical means in the art.

[0065] The method described in the present application realizes the regulation of the isomerization degree of the saturated hydrocarbons in the Fischer-Tropsch hydrogenation tail oil in the one-stage reaction and the two-stage reaction by limiting the relationship between the catalyst components, the acid amount, the specific surface area and the pore volume used in the one-stage reaction and the two-stage reaction, and further matching the limited catalyst with the reaction conditions used in the one-stage reaction and the two-stage reaction, so as to ensure that the light components in the Fischer-Tropsch hydrogenation tail oil realize hydrogenation isomerization in the one-stage reaction without the hydrogenation isomerization of the heavy components, the heavy components in the material obtained by the one-stage reaction are subjected to hydrogenation isomerization in the two-stage reaction, so as to ensure that the lubricating oil base oil with different viscosities and low pour points is prepared, the product yield is high, the Fischer-Tropsch hydrogenation tail oil is fully utilized, the raw material cost is further saved on the basis of preparing the product with high quality, and the method described in the present application omits the pretreatment process of the Fischer-Tropsch hydrogenation tail oil, further simplifies the preparation process, and is more conducive to industrialization.

[0066] The present application will be described in detail below through examples, but the protection scope of the present application is not limited thereto.

[0067] The distillation range of the Fischer-Tropsch hydrogenation tail oil used in the following examples and comparative examples is 350-740℃, and the content of saturated hydrocarbons is ≥90%, and the simulated distillation range data of the raw material are shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] The component information of the catalysts used in the following examples and comparative examples is shown in Table 2, the specific surface area, pore volume, weak acid amount, medium strong acid amount and total acid amount of the catalysts used are shown in Table 3, and the binder contained in the first hydroisomerization catalysts A1 to A5 is all alumina, the binder contained in the second hydroisomerization catalysts B1 to B5 is all alumina, and the binder contained in the hydroisomerization catalysts D1, the first hydroisomerization catalyst D3 and the second hydroisomerization catalyst D4 is all alumina.

[0072] In the following examples and comparative examples, the pour point of the base oil is tested according to the national standard GB / T 3535-2006 "Determination of pour point of petroleum products", and the kinematic viscosity at 100°C and the viscosity index are tested according to the national standard GB / T 265-1988 "Determination of kinematic viscosity of petroleum products and calculation of dynamic viscosity".

[0073] Example 1

[0074] The Fischer-Tropsch hydrocracking tail oil is subjected to a one-stage reaction with hydrogen in the presence of the first hydroisomerization catalyst A1, then the obtained reaction material is subjected to a two-stage reaction with hydrogen in the presence of the second hydroisomerization catalyst B1, and then the obtained reaction material is subjected to a three-stage reaction with hydrogen in the presence of the third hydroisomerization catalyst C1 (the carrier is large-pore alumina, the active metal is Pd, and the active metal loading is 0.5 wt%), and then the obtained material is subjected to rectification, and the product is cut as follows: naphtha < 150°C, light white oil fraction 150-260°C, diesel fraction 260-350°C, base oil fraction > 350°C, 3 cSt base oil 350-400°C, 4 cSt base oil 400-450°C, 6 cSt base oil 450-530°C, 30 cSt base oil > 530°C, and the properties of the obtained base oil are tested, and the results are shown in Table 3.

[0075] The reaction temperature of the one-stage reaction is 330°C, the volume space velocity is 1.0 h -1 -1, the hydrogen partial pressure is 3 MPa, and the hydrogen / oil volume ratio is 600:1; the reaction temperature of the two-stage reaction is 335°C, the volume space velocity is 0.9 h -1 -1, the hydrogen partial pressure is 5 MPa, and the hydrogen / oil volume ratio is 600:1; the reaction temperature of the three-stage reaction is 250°C, the hydrogen partial pressure is 5 MPa, and the hydrogen / oil volume ratio is 600:1.

[0076] Table 3

[0077]

[0078] Example 2

[0079] In the presence of the first hydroisomerization catalyst A2, the Fischer-Tropsch hydrotreated tail oil was reacted with hydrogen in a first-stage reaction. The resulting reactants were then reacted with hydrogen in a second-stage reaction in the presence of the second hydroisomerization catalyst B2. Finally, the resulting reactants were reacted with hydrogen in a third-stage reaction in the presence of the third hydroisomerization catalyst C2 (supported by macroporous alumina, with Pd as the active metal and an active metal loading of 0.5 wt%). The resulting material was then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, and 30cSt base oil >530℃. The performance of the obtained base oils was tested, and the results are shown in Table 4.

[0080] The reaction temperature of the first stage was 325℃, and the volume hourly space velocity was 1.2 h⁻¹. -1 The hydrogen partial pressure was 3.5 MPa, and the hydrogen-to-oil volume ratio was 800:1; the reaction temperature of the second-stage reaction was 338℃, and the volume hourly space velocity was 1.0 h⁻¹. -1 The hydrogen partial pressure is 6 MPa, and the hydrogen-to-oil volume ratio is 800:1; the reaction temperature of the three-stage reaction is 250℃, the hydrogen partial pressure is 6 MPa, and the hydrogen-to-oil volume ratio is 800:1.

[0081] Table 4

[0082]

[0083] Example 3

[0084] In the presence of the first hydroisomerization catalyst A3, the Fischer-Tropsch hydrotreated tail oil was reacted with hydrogen in a first-stage reaction. The resulting reactants were then reacted with hydrogen in a second-stage reaction in the presence of the second hydroisomerization catalyst B3. Finally, the resulting reactants were reacted with hydrogen in a third-stage reaction in the presence of the third hydroisomerization catalyst C3 (supported by macroporous alumina, with Pd as the active metal and an active metal loading of 0.5 wt%). The resulting material was then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, and 30cSt base oil >530℃. The properties of the obtained base oils were tested, and the results are shown in Table 5.

[0085] The reaction temperature of the first stage was 335℃, and the volume hourly space velocity was 1.4 h⁻¹. -1 The hydrogen partial pressure was 4 MPa, and the hydrogen-to-oil volume ratio was 800:1; the reaction temperature of the second-stage reaction was 340℃, and the volume hourly space velocity was 1.2 h⁻¹. -1The hydrogen partial pressure is 7 MPa, and the hydrogen-to-oil volume ratio is 800:1; the reaction temperature of the three-stage reaction is 240℃, the hydrogen partial pressure is 7 MPa, and the hydrogen-to-oil volume ratio is 800:1.

[0086] Table 5

[0087]

[0088] Example 4

[0089] In the presence of the first hydroisomerization catalyst A4, the Fischer-Tropsch hydrotreated tail oil was reacted with hydrogen in a first-stage reaction. The resulting reactants were then reacted with hydrogen in a second-stage reaction in the presence of the second hydroisomerization catalyst B4. Finally, the resulting reactants were reacted with hydrogen in a third-stage reaction in the presence of the third hydroisomerization catalyst C4 (supported by macroporous alumina, with Pd as the active metal and an active metal loading of 0.5 wt%). The resulting material was then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, and 30cSt base oil >530℃. The properties of the obtained base oils were tested, and the results are shown in Table 6.

[0090] The reaction temperature of the first stage was 320℃, and the volume hourly space velocity was 0.8 h⁻¹. -1 The hydrogen partial pressure was 4.5 MPa, and the hydrogen-to-oil volume ratio was 600:1; the reaction temperature of the second-stage reaction was 330℃, and the volume hourly space velocity was 0.8 h⁻¹. -1 The hydrogen partial pressure was 5 MPa, and the hydrogen-to-oil volume ratio was 600:1; the reaction temperature of the three-stage reaction was 240℃, the hydrogen partial pressure was 5 MPa, and the hydrogen-to-oil volume ratio was 600:1.

[0091] Table 6

[0092]

[0093] Example 5

[0094] In the presence of the first hydroisomerization catalyst A5, the Fischer-Tropsch hydrotreated tail oil was reacted with hydrogen in a first-stage reaction. The resulting reactants were then reacted with hydrogen in a second-stage reaction in the presence of the second hydroisomerization catalyst B5. Finally, the resulting reactants were reacted with hydrogen in a third-stage reaction in the presence of the third hydroisomerization catalyst C5 (supported by macroporous alumina, with Pd as the active metal and an active metal loading of 0.5 wt%). The resulting product was then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, and 30cSt base oil >530℃. The properties of the obtained base oils were tested, and the results are shown in Table 7.

[0095] The reaction temperature of the first stage was 325℃, and the volume hourly space velocity was 1.0 h⁻¹. -1 The hydrogen partial pressure was 5 MPa, and the hydrogen-to-oil volume ratio was 600:1; the reaction temperature of the second-stage reaction was 335℃, and the volume hourly space velocity was 0.7 h⁻¹. -1 The hydrogen partial pressure is 8 MPa, and the hydrogen-to-oil volume ratio is 600:1; the reaction temperature of the three-stage reaction is 260℃, the hydrogen partial pressure is 8 MPa, and the hydrogen-to-oil volume ratio is 600:1.

[0096] Table 7

[0097]

[0098] Comparative Example 1

[0099] In the presence of hydroisomerization catalyst D1, Fischer-Tropsch hydrotreated tail oil and hydrogen were subjected to hydroisomerization reaction. Then, the resulting reactants and hydrogen were subjected to hydrogenation reaction in the presence of catalyst D2 (supported by macroporous alumina, active metal is Pd, active metal loading is 0.5 wt%). The resulting materials were then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, 30cSt base oil >530℃. The performance of the obtained base oils was tested, and the results are shown in Table 8.

[0100] The hydroisomerization reaction was carried out at a temperature of 330°C and a volume hourly space velocity (VHSV) of 1.0 h⁻¹. -1 The hydrogen partial pressure is 3 MPa, and the hydrogen-to-oil volume ratio is 600:1; the reaction temperature of the hydrogenation reaction is 250℃, the hydrogen partial pressure is 3 MPa, and the hydrogen-to-oil volume ratio is 600:1.

[0101] Table 8

[0102]

[0103]

[0104] Comparative Example 2

[0105] In the presence of the first hydroisomerization catalyst D3, the Fischer-Tropsch hydrotreated tail oil was reacted with hydrogen in a first-stage reaction. The resulting reactants were then reacted with hydrogen in a second-stage reaction in the presence of the second hydroisomerization catalyst D4. Finally, the resulting reactants were reacted with hydrogen in a third-stage reaction in the presence of the third hydroisomerization catalyst D5 (supported by macroporous alumina, with Pd as the active metal and an active metal loading of 0.5 wt%). The resulting product was then distilled, and the products were divided as follows: naphtha <150℃, light white oil fraction 150-260℃, diesel fraction 260-350℃, base oil fraction >350℃, 3cSt base oil 350-400℃, 4cSt base oil 400-450℃, 6cSt base oil 450-530℃, and 30cSt base oil >530℃. The properties of the obtained base oils were tested, and the results are shown in Table 9.

[0106] The reaction temperature of the first stage was 345℃, and the volume hourly space velocity was 1.0 h⁻¹. -1 The hydrogen partial pressure was 3 MPa, and the hydrogen-to-oil volume ratio was 600:1; the reaction temperature of the second-stage reaction was 320℃, and the volume hourly space velocity was 0.9 h⁻¹. -1 The hydrogen partial pressure is 3 MPa, and the hydrogen-to-oil volume ratio is 600:1; the reaction temperature of the three-stage reaction is 250℃, the hydrogen partial pressure is 3 MPa, and the hydrogen-to-oil volume ratio is 600:1.

[0107] Table 9

[0108]

[0109]

[0110] Table 2

[0111]

[0112]

[0113] Note: The Si / Al ratio in parentheses after the molecular sieve model number is the Si / Al ratio of the molecular sieve. For example, ZSM-48(110) indicates that the selected ZSM-48 molecular sieve has a Si / Al ratio of 110, ZSM-48(100) indicates that the selected ZSM-48 molecular sieve has a Si / Al ratio of 100, ZSM-48(130) indicates that the selected ZSM-48 molecular sieve has a Si / Al ratio of 130, ZSM-48(120) indicates that the selected ZSM-48 molecular sieve has a Si / Al ratio of 120, and ZSM-22(80) indicates that the selected ZSM-22 molecular sieve... The silicon-to-aluminum ratio in the selected ZSM-22 molecular sieve is 80. ZSM-22(100) indicates that the silicon-to-aluminum ratio in the selected ZSM-22 molecular sieve is 100. ZSM-23(70) indicates that the silicon-to-aluminum ratio in the selected ZSM-23 molecular sieve is 70. ZSM-23(120) indicates that the silicon-to-aluminum ratio in the selected ZSM-23 molecular sieve is 120. SAPO-11(0.6) indicates that the silicon-to-aluminum ratio in the selected SAPO-11 molecular sieve is 0.6. SAPO-11(0.75) indicates that the silicon-to-aluminum ratio in the selected SAPO-11 molecular sieve is 0.75.

[0114] Table 3

[0115]

[0116]

[0117] Comparative Example 3

[0118] The method was implemented according to Example 1, except that the first hydroisomerization catalyst had a total acid content of 0.64 mmol / g, a weak acid content of 0.36 mmol / g, a moderately strong acid content of 0.28 mmol / g, and a specific surface area of ​​130 m². 2 / g, pore volume 0.22cm 3 / g, the total acidity of the second hydroisomerization catalyst is 0.57 mmol / g, the weak acidity is 0.37 mmol / g, the moderately strong acidity is 0.2 mmol / g, and the specific surface area is 145 m² / g. 2 / g, pore volume 0.26cm 3 / g, the properties of the obtained base oil were tested, and the results are shown in Table 10.

[0119] Table 10

[0120]

[0121]

[0122] Comparative Example 4

[0123] The method was implemented according to Example 1, except that the temperature of the first-stage reaction was 295°C and the temperature of the second-stage reaction was 355°C. The properties of the obtained base oil were tested, and the results are shown in Table 11.

[0124] Table 11

[0125]

[0126] Comparative Example 5

[0127] The method was implemented according to Example 1, except that the hydrogen partial pressure of the first-stage reaction was 8 MPa and the hydrogen partial pressure of the second-stage reaction was 10 MPa. The properties of the obtained base oil were tested, and the results are shown in Table 12.

[0128] Table 12

[0129]

[0130] Test data from the examples and comparative examples show that the method described in this invention can directly prepare base oil products by hydroisomerization of Fischer-Tropsch hydrotreated tail oil without the need for distillation and cutting, thus reducing raw material waste. Furthermore, the prepared base oil has a low pour point, good product quality, and high yield, further simplifying the preparation process and making it more conducive to industrial production.

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing lubricating oil base oil using Fischer-Tropsch hydrotreated tail oil, characterized in that, The method includes: sequentially subjecting Fischer-Tropsch hydrotreated tail oil to hydrogen through a first-stage reaction, a second-stage reaction, and a third-stage reaction, and then distilling the reacted material. The first-stage reaction is carried out in the presence of the first hydroisomerization catalyst, and the second-stage reaction is carried out in the presence of the second hydroisomerization catalyst; the total acid content of the first hydroisomerization catalyst is greater than the total acid content of the second hydroisomerization catalyst, and the specific surface area and pore volume of the first hydroisomerization catalyst are smaller than the specific surface area and pore volume of the second hydroisomerization catalyst. The first hydroisomerization catalyst contains a first support and a first noble metal component supported on the first support, and the second hydroisomerization catalyst contains a second support and a second noble metal component supported on the second support. The first support contains a first molecular sieve and a first binder, and the second support contains a second molecular sieve and a second binder. The first molecular sieve and the second molecular sieve are each selected from one or more of ZSM-48, ZSM-22, ZSM-23 and SAPO-11; the weak acid content of the first hydroisomer catalyst and the second hydroisomer catalyst is 0.1-0.35 mmol / g, and the medium-strong acid content is 0.05-0.3 mmol / g; The conditions for the first-stage reaction include: a temperature of 300-350℃, a hydrogen partial pressure of 2-10 MPa, and a volume hourly space velocity of 0.3-2 h⁻¹. -1 ; The conditions for the two-stage reaction include: a temperature of 300-350℃, a hydrogen partial pressure of 2-10 MPa, and a volume hourly space velocity of 0.3-2 h⁻¹. -1 The temperature of the first-stage reaction is less than or equal to the temperature of the second-stage reaction, and the hydrogen partial pressure of the first-stage reaction is less than or equal to the hydrogen partial pressure of the second-stage reaction.

2. The method according to claim 1, characterized in that, The specific surface area of ​​the second hydroisomerization catalyst is 20-60 m² larger than that of the first hydroisomerization catalyst. 2 / g, the pore volume of the second hydroisomerization catalyst is 0.03-0.18 cm³ larger than that of the first hydroisomerization catalyst. 3 / g; Preferably, the specific surface area of ​​the first hydroisomerization catalyst and the second hydroisomerization catalyst is ≥150 m². 2 / g, the pore volume of the first and second hydroisomerization catalysts is ≤0.5cm³. 3 / g; Preferably, the specific surface area of ​​the first hydroisomerization catalyst is 150-250 m². 2 / g, the specific surface area of ​​the second hydroisomerization catalyst is 180-250m². 2 / g; Preferably, the pore volume of the first hydroisomerization catalyst is 0.25-0.5 cm³. 3 / g, the pore volume of the second hydroisomerization catalyst is 0.3-0.5 cm³. 3 / g.

3. The method according to claim 1 or 2, characterized in that, The first noble metal component and the second noble metal component are each Pt and / or Pd; Preferably, the content of the first noble metal component is 3-5 parts by weight relative to 100 parts by weight of the first carrier; Preferably, the content of the second noble metal component is 3-5 parts by weight relative to 100 parts by weight of the second carrier.

4. The method according to any one of claims 1-3, characterized in that, The temperature of the first-stage reaction is 5-20°C lower than the temperature of the second-stage reaction; Preferably, the temperature of the first-stage reaction is 305-330℃, and the temperature of the second-stage reaction is 310-340℃.

5. The method according to any one of claims 1-4, characterized in that, The hydrogen partial pressure of the first-stage reaction is 0.2-4 MPa lower than that of the second-stage reaction; Preferably, the hydrogen partial pressure in the first stage reaction is 3-5 MPa, and the hydrogen partial pressure in the second stage is 5-8 MPa.

6. The method according to any one of claims 1-5, characterized in that, The hydrogen-to-oil volume ratio in the first-stage reaction is 200-2000:1; and / or The hydrogen-to-oil volume ratio in the two-stage reaction is 200-2000:

1.

7. The method according to any one of claims 1-6, characterized in that, The three-stage reaction is carried out in the presence of a third hydrogenation catalyst; Preferably, the third hydrogenation catalyst contains a support and an active metal component, wherein the support is macroporous alumina and / or silica-alumina, and the metal in the active metal component is selected from one or more of Pt, Pd, Ni and W.

8. The method according to claim 1 or 7, characterized in that, The conditions for the three-stage reaction include: a temperature of 200-280℃ and a volume hourly space velocity of 0.2-2 h⁻¹. -1 The hydrogen-to-oil volume ratio is 200-2000:1, and the hydrogen partial pressure is 2-10 MPa.

9. The method according to any one of claims 1-8, characterized in that, The first molecular sieve has a silica-to-alumina ratio of 50-150, and the second molecular sieve has a silica-to-alumina ratio of 0.5-150. Preferably, the first molecular sieve is one or more of ZSM-48, ZSM-22 and ZSM-23, and the second molecular sieve is one or more of ZSM-48, SAPO-11 and ZSM-23; Preferably, the silicon-to-aluminum ratio of ZSM-22 is 60-90, the silicon-to-aluminum ratio of ZSM-23 is 100-140, the silicon-to-aluminum ratio of ZSM-48 is 100-150, and the silicon-to-aluminum ratio of SAPO-11 is 0.5-1.

10. The method according to any one of claims 1-9, characterized in that, In the first hydroisomerization catalyst, the weight ratio of the first binder to the first molecular sieve is 0.3-0.8:1; Preferably, in the second hydroisomerization catalyst, the weight ratio of the second binder to the second molecular sieve is 0.28-0.7:

1.

11. The method according to any one of claims 1-10, characterized in that, In the material after the first stage of reaction, the mass content corresponding to a distillation temperature of 350℃ is ≤10%.

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