Method for producing lubricating base oil from coal liquefaction oil

Abstract

The invention discloses a method for producing lubricating base oil from coal liquefaction oil, and belongs to the technical field of coal chemical industry. The method comprises the following steps: firstly, by taking coal liquefaction hydrogenation stabilized oil as raw material oil, fractionating the raw material oil to obtain liquefied oil medium fraction and heavy fraction; mixing the medium fraction and the heavy fraction according to a certain proportion; the obtained mixed fraction is subjected to hydrofining, and a hydrogenation catalyst used in hydrofining is prepared by taking modified Al-SBA-15 as a carrier and loading active metal Mo through an impregnation method; and finally, carrying out hydrodewaxing and product fractionation on the hydrofined material to obtain the product. The acidity and hydrogenation activity of the catalyst can be adjusted by adjusting the preparation conditions of the Al-SBA-15 carrier and the loaded active components, so that the hydrogenation requirements of different liquefied oil fractions can be met. The performance of the lubricating base oil is improved, the service life of the lubricating base oil is prolonged, and the requirement of modern industry for high-quality lubricating oil is met.

Description

Technical Field

[0001] The invention belongs to the technical field of coal chemical industry, and in particular relates to a method for producing lubricating base oil from coal liquefaction oil. Background Art

[0002] The production of lubricating oil components from coal liquefaction heavy oil fractions is an important technology involving multiple key steps and technical links, including raw material pretreatment, catalytic hydrotreating, isomerization, distillation separation, post-processing processes, etc. Finally, a series of physical and chemical tests are performed to ensure that the viscosity, oxidation stability, low-temperature fluidity and other indicators of the lubricating oil components meet the standards.

[0003] The relevant research of existing technology mainly includes:

[0004] Application No. 202211393401.9 discloses a method and application of producing lubricating base oil by hydrogenating heavy oil from Fischer-Tropsch, which includes: cutting Fischer-Tropsch hydrogenated heavy oil into fractions of different temperature ranges, and performing hydrogenation isomerization, atmospheric distillation cutting, supplementary refining and vacuum distillation on specific fractions, and finally obtaining a variety of lubricating base oils, and improving the yield and viscosity of the base oil by narrow distillation range cutting. Application No. 201310103189.2 discloses a method of hydrogenating full-fraction coal tar to produce fuel oil and lubricating base oil, which is to hydrogenate the full-fraction coal tar, depressurize it through a pressure reducing valve, and then flash separate the light product and the heavy product, and further isomerize and dewax the heavy product, and then successively pass through hot and cold high-fraction separators, cold low-fraction separators and fractionation towers with the light product to obtain fuel oil and lubricating base oil. Through this technology, low-cost coal tar can be efficiently converted into high-value-added fuel oil and lubricating base oil, and resources are effectively utilized. The fuel oil and lubricant base oil produced have better physical and chemical properties, such as high saturation, low aromatic content and excellent low temperature performance.

[0005] The prior art has made certain research progress in the preparation of lubricating oil, but there are still the following technical problems:

[0006] Some of the above methods involve more process units and can only supplement and refine specific fractions, affecting the quality of the lubricating oil; some involve multiple complex process steps, such as pretreatment, catalytic hydrogenation, hydrocracking, hydrogenation saturation, etc., with a deeper hydrogenation depth and more stringent conditions for sulfur and nitrogen removal. Summary of the invention

[0007] The object of the present invention is to provide a method for producing lubricating base oil from coal liquefied oil, which uses coal liquefied hydrogenated and stabilized oil as raw material, mixes the middle fraction and the heavy fraction in the liquefied oil, and then hydrogenates the mixed fractions, improves the performance and service life of the lubricating base oil by optimizing the process and adding a specific modifier, and meets the demand of modern industry for high-quality lubricating oil.

[0008] The above-mentioned method for producing lubricating base oil from coal liquefaction oil comprises the following steps:

[0009] S1, using coal liquefaction hydrogenation stabilized oil as raw oil, fractionating the raw oil at 200-230°C and 400-430°C, and obtaining a liquefied oil middle fraction and a heavy fraction through fractionation;

[0010] S2, mixing the middle fraction and the heavy fraction in a certain proportion;

[0011] S3, performing hydrofining on the mixed fraction obtained in S2, wherein the hydrogenation catalyst used in the hydrofining is prepared by using modified Al-SBA-15 as a carrier and loading active metal Mo by an impregnation method;

[0012] S4. The hydrorefined material is subjected to hydrodewaxing and product fractionation to obtain lubricating base oil.

[0013] In the above method for producing lubricating base oil from coal liquefaction oil, in step S2, the middle fraction and the heavy fraction are mixed according to the mass percentages of 10-30% and 70-90%.

[0014] In the above-mentioned method for producing lubricating base oil from coal liquefaction oil, in step S3, the hydrorefining is carried out in a fixed reaction bed, the reaction pressure is 9-11 MPa, the reaction temperature is 310-340°C, and the liquid hourly space velocity is 0.6-1.2h -1 .

[0015] In the above method for producing lubricating base oil from coal liquefaction oil, in step S3, the loading amount of the active metal is 5-20% based on the weight of the hydrogenation catalyst.

[0016] In the above method for producing lubricating base oil from coal liquefaction oil, in step S3, the preparation step of the hydrogenation catalyst is:

[0017] Preparation of a carrier: including preparation of an aluminum source, preparation of a template solution, mixing and acidification steps to obtain an HCl-modified Al-SBA-15 carrier;

[0018] Loading: impregnating the HCl-modified Al-SBA-15 carrier with the ammonium molybdate solution by an equal volume method, and mixing the two uniformly by stirring and shaking to obtain an impregnated mixture;

[0019] Drying treatment: Dry the impregnated mixture to remove moisture;

[0020] Calcination activation: The sample obtained after drying is calcined at a certain temperature. During the calcination process, ammonium molybdate decomposes to form MoO3, which is firmly attached to the modified Al-SBA-15 carrier.

[0021] In the above method for producing lubricating base oil from coal liquefaction oil, the preparation steps of the aluminum source are:

[0022] Aluminum isopropoxide is dried to remove moisture adsorbed on its surface; a dispersant is added to the dried aluminum isopropoxide to ensure that the aluminum isopropoxide particles are evenly dispersed; the evenly dispersed aluminum isopropoxide is then placed in a ball mill for crushing treatment, so that the crushed particle size is uniform and the particle size reaches nanometer level; the aluminum isopropoxide after ball milling treatment is dispersed in anhydrous ethanol for ultrasonic treatment; the ethanol in the aluminum isopropoxide solution after ultrasonic dispersion is evaporated, and the obtained aluminum isopropoxide is dried to obtain the treated aluminum isopropoxide powder as an aluminum source.

[0023] In the above-mentioned method for producing lubricating base oil from coal liquefaction oil, the template solution is prepared by adding a certain amount of triblock copolymer P123 into anhydrous ethanol for dissolution, and the mass ratio of the triblock copolymer P123 to anhydrous ethanol is 1:5-10.

[0024] The above-mentioned method for producing lubricating base oil from coal liquefaction oil comprises the following steps of mixing and acidifying: adding a certain amount of ethyl silicate, treated aluminum isopropoxide powder and hydrochloric acid to a template solution for mixing and stirring, starting stirring and controlling the temperature during the acidification process with hydrochloric acid, and maintaining the acidification temperature at room temperature to 30°C; when the mixture is stirred until it becomes a light white translucent liquid, reacting for a period of time, covering the reaction mixture with a polyethylene film, and performing an aging treatment, and obtaining an HCl-modified Al-SBA-15 carrier after drying and calcining.

[0025] The above-mentioned method for producing lubricating base oil from coal liquefaction oil comprises placing aluminum isopropoxide in a vacuum drying oven for drying, setting the temperature to 90-110° C., and drying time to 1-3 hours; the dispersant is one or two of sodium polyacrylate, polycarboxylate, lignin sulfonate, fatty acid polyethylene glycol ester, alkylphenol polyoxyethylene ether, polyvinyl pyrrolidone, and Tween; and the dispersant accounts for 0.5-2% of the aluminum isopropoxide after drying in terms of mass percentage.

[0026] In the above-mentioned method for producing lubricating base oil from coal liquefaction oil, the molar ratio of hydrochloric acid to ethyl silicate is 0.1:1 to 1:1, the aging treatment temperature is 45 to 55°C, and the aging treatment time is 20 to 25 hours; the drying temperature after aging is 100 to 110°C, and the drying time is 6 to 9 hours; the roasting temperature is 450 to 550°C, and the roasting time is 3 to 5 hours.

[0027] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0028] (1) The present invention proposes a method for producing lubricating base oil from coal liquefaction oil, using coal liquefaction hydrogenated and stabilized oil as raw material, mixing the middle fraction and the heavy fraction in the liquefied oil, and then hydrogenating and modifying the mixed fraction. The coal direct liquefaction oil rich in aromatics has a specific chemical structure after hydrogenation modification. These alkyl aromatic structures can enhance the strength of the oil film and improve the lubrication performance in the lubricating oil. The coal direct liquefaction oil fraction has a relatively uniform molecular structure and a certain molecular weight, so it can still maintain stable and excellent lubrication performance under high temperature conditions. This stability enables it to provide continuous and effective lubrication in extreme working environments.

[0029] (2) The modified Al-SBA-15 carrier has a very high internal surface area, which is 10,000 to 100,000 times higher than the surface area of ​​the particles. This structural feature enables SBA-15 to load more active components and provide more reaction sites, thereby enhancing catalytic activity. The uniform pore structure is conducive to the diffusion of reactants and products, reduces mass transfer resistance, and improves reaction efficiency. More importantly, it has significant low-temperature hydrogenation activity, which can significantly reduce the temperature of hydrorefining; secondly, it has good thermal and chemical stability, and can maintain structural stability under the harsh conditions of hydrogenation of liquefied oil and heavy oil fractions, ensuring the long-term operation of the catalyst. By adjusting the preparation conditions of the Al-SBA-15 carrier and the active components loaded, the acidity and hydrogenation activity of the catalyst can be adjusted to meet the hydrogenation requirements of different liquefied oil fractions. DETAILED DESCRIPTION

[0030] The present invention provides a method for producing lubricating base oil from coal liquefaction oil. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is further described below in conjunction with specific embodiments.

[0031] First, the preparation of the hydrogenation catalyst of the present invention is described in detail.

[0032] The preparation steps of the hydrogenation catalyst mainly include the preparation of the catalyst carrier and the loading steps of the active metal on the catalyst carrier.

[0033] 1. Preparation of catalyst carrier:

[0034] 1.1. Preparation of aluminum source: Dry and crushed ultrafine aluminum isopropoxide is used as an aluminum source, which is added to tetraethyl silicate (TEOS). The mixture is recorded as TEOS-Al, and the mixture is mixed at a molar ratio of 5 to 20:1 between tetraethyl silicate and aluminum isopropoxide.

[0035] Furthermore, the above aluminum source preparation steps are:

[0036] (1) The raw material is selected from high-purity aluminum isopropoxide (Al(OC3H7)3), and its purity is ensured to be above 99.9% to reduce the influence of impurities on the catalyst performance.

[0037] (2) Drying the aluminum isopropoxide in a vacuum drying oven at 90 to 110° C. for 1 to 3 hours using a drying unit, the purpose of which is to remove moisture adsorbed on the surface. In order to further refine the particles and prevent agglomeration, an appropriate amount of dispersant is added to the dried aluminum isopropoxide to ensure uniform dispersion of the particles, specifically: the weighed dispersant is evenly sprinkled on the surface of the aluminum isopropoxide powder, and the dispersant accounts for 0.5 to 2% of the dried aluminum isopropoxide in terms of mass percentage, and is pre-mixed manually to ensure that the dispersant is initially evenly distributed.

[0038] (3) placing aluminum isopropoxide in a ball mill, setting the ball milling time to 4 hours, the rotation speed to 300 rpm, the ball milling medium to zirconia beads, the mass ratio to 1:10, to ensure that the particle size after crushing is uniform and the particle size reaches the nanometer level; dispersing the crushed aluminum isopropoxide in anhydrous ethanol, using ultrasonic treatment for 30 minutes to further refine the particles and improve the dispersion uniformity; evaporating the ethanol from the aluminum isopropoxide solution after ultrasonic dispersion in a rotary evaporator, and then drying in a vacuum drying oven at 60° C. for 12 hours to obtain dried and crushed ultrafine aluminum isopropoxide powder; placing the prepared ultrafine aluminum isopropoxide powder in a dryer to avoid contact with air and moisture to ensure its stability

[0039] 1.2 Preparation of template solution: Take an appropriate amount of Pluronic triblock copolymer P123, add it into anhydrous ethanol to dissolve it, the mass ratio of triblock copolymer P123 to anhydrous ethanol is 1:5-10, and a light white translucent solution is obtained.

[0040] 1.3. Mixing and acidification: Add appropriate amount of TEOS-Al and hydrochloric acid to the P123 solution, wherein the molar ratio of HCl to TEOS is 0.1:1 to 1:1. Slowly add the hydrochloric acid solution drop by drop into the mixed solution, and increase the stirring rate appropriately to avoid excessive reaction caused by excessive local concentration.

[0041] Temperature control is required during acidification: During the acidification process, the solution temperature is maintained between room temperature and 30°C to prevent excessive temperature from affecting the uniformity of the reaction. In order to achieve a better mixing effect, a stirrer can be used for continuous stirring. After the acidification is completed, continue stirring for 30 minutes to ensure that the reaction is uniform. Observation state: Observe the state of the solution to ensure that it presents a uniform light white translucent liquid. Stir the above P123 solution with a mixture of TEOS and aluminum isopropoxide and react for 30 minutes. Cover the mixture with a microporous polyethylene film and age it in a drying oven at a temperature of 45 to 55°C for 20 to 25 hours. After aging, the sample is dried at a temperature of 100 to 110°C for 6 to 9 hours. The dried sample is calcined at 450 to 550°C for 3 to 5 hours to finally prepare an HCl-modified Al-SBA-15 carrier.

[0042] 2. Preparation of Catalysts by Loading Active Metals

[0043] In the process of preparing Mo series catalysts by equal volume impregnation method, modified Al-SBA-15 is used as a carrier, and ammonium molybdate ((NH4)6Mo7O4·4H2O) is used as a Mo source. The specific preparation steps are as follows:

[0044] 2.1. Prepare ammonium molybdate aqueous solution: According to the predetermined MoO3 loading (5.0-20%), accurately calculate and weigh the corresponding mass of ammonium molybdate. Dissolve ammonium molybdate in deionized water to prepare a series of ammonium molybdate aqueous solutions with different concentrations.

[0045] 2.2. Isocratic impregnation: Isocratize an equal volume of the dried modified Al-SBA-15 in the prepared aqueous solution of ammonium molybdate. Ensure uniform mixing by sufficient stirring or shaking so that the ammonium molybdate can be evenly loaded on the carrier.

[0046] 2.3 Drying: The impregnated mixture is placed in a vacuum oven at 100°C for 24 hours for drying. This step is to remove moisture from the mixture and prepare for the subsequent roasting process.

[0047] 2.4. Calcination and activation: After drying, the sample was placed in a muffle furnace and calcined at 500°C for 4 hours in an air atmosphere. During the calcination process, ammonium molybdate will decompose to form MoO3, which will be firmly attached to the modified Al-SBA-15 carrier, thus completing the preparation of the catalyst.

[0048] Sample labeling and storage: After calcination, the catalyst samples were taken out, labeled as MoO3 / Al-SBA-15, and classified and stored according to different MoO3 loading amounts (5%, 10%, 15%) for subsequent use.

[0049] 3. The hydrogenation catalyst prepared above is applied to a method of producing lubricating base oil from coal liquefaction oil of the present invention, and the specific steps are as follows:

[0050] First, the coal liquefaction hydrogenation stabilized oil is used as the raw oil, and the raw oil is fractionated at 200-230°C and 400-430°C to obtain the liquefied oil middle fraction and heavy fraction through fractionation; then, the middle fraction and the heavy fraction are mixed according to the mass percentage of 10-30% and 70-90%. The obtained mixed fraction is subjected to hydrogenation refining, and the above-mentioned hydrogenation catalyst is used in the hydrogenation refining; finally, the material after hydrogenation refining is subjected to hydrogenation dewaxing and product fractionation to obtain the lubricating base oil.

[0051] In the above-mentioned method for producing lubricating base oil from coal liquefaction oil, the reaction pressure during hydrofining is preferably 9-11 MPa. This reaction pressure helps to increase the solubility of hydrogen in the feedstock oil, thereby improving the rate and efficiency of the hydrogenation reaction. The reaction temperature is preferably 310-340°C. This temperature can not only ensure the smooth progress of the hydrogenation reaction, but also avoid the deactivation of the catalyst due to high temperature, thereby extending the service life of the catalyst. The liquid hourly space velocity (LHSV) is preferably 0.6-1.2h -1 , which means that the residence time of the crude oil in the reactor is moderate, which not only ensures sufficient reaction time but also avoids side reactions that may be caused by too long residence time.

[0052] The present invention is described in detail below with reference to specific embodiments.

[0053] Embodiment 1:

[0054] Step 1: Preparation of hydrogenation catalyst:

[0055] The aluminum isopropoxide is dried in a vacuum drying oven at 100°C for 2 hours to remove the moisture adsorbed on the surface; 20% mass concentration of fatty acid polyethylene glycol ester is added, wherein the amount of fatty acid polyethylene glycol ester added is 1% relative to the aluminum isopropoxide, and the weighed dispersant is evenly sprinkled on the surface of the aluminum isopropoxide powder, and manually premixed to make the dispersant initially evenly distributed to ensure that the particles are evenly dispersed; the aluminum isopropoxide is placed in a ball mill, and the ball milling time is set to 4 hours, the speed is 300rpm, and the ball milling medium is zirconium oxide beads, and the mass ratio is 1:10. The crushed aluminum isopropoxide is dispersed in anhydrous ethanol and treated with ultrasound for 30 minutes; the aluminum isopropoxide solution after ultrasonic dispersion is evaporated in a rotary evaporator to remove ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain dry and crushed ultrafine aluminum isopropoxide powder; the prepared ultrafine aluminum isopropoxide powder is placed in a dryer to avoid contact with air and moisture to ensure its stability.

[0056] Ethyl silicate (TEOS, molar mass 208.33 g / mol) was used as a silicon source and mixed with dried and crushed ultrafine aluminum isopropoxide (molar mass 204.33 g / mol) at a molar ratio of 20:1. Pluronic triblock copolymer P123 was selected as a template reagent, and an appropriate amount of P123 was dissolved in anhydrous ethanol to obtain a light white translucent solution. Then, an appropriate amount of hydrochloric acid was added to the solution to ensure that the molar ratio of HCl to TEOS was maintained at 4:1, and stirred with the previous mixture for 30 minutes. After that, it was covered with a microporous polyethylene film and aged in a drying oven at 50°C for 24 hours. Finally, after drying at 105°C for 8 hours and calcining at 500°C for 4 hours, the HCl-modified Al-SBA-15 carrier was finally prepared.

[0057] The Mo source is ammonium molybdate, and the specific steps are as follows: the dried modified A1-SBA-15 is immersed in an aqueous solution of ammonium molybdate, mixed evenly, dried in a vacuum oven at 100°C for 24 hours, and calcined in a muffle furnace at 500°C for 4 hours under an air atmosphere to obtain a catalyst sample, which is recorded as MoO / A1SBA-15, and the MoO loading amounts are 5%, 10%, and 15%, respectively.

[0058] Step 2: Coal liquefaction oil production lubricating base oil

[0059] The raw material oil is liquefied oil stabilized by hydrogenation, and its main properties are shown in Table 1. The liquefied oil is distilled to cut out a fraction of <230°C, a fraction of 230-400°C, and a fraction of >400°C. The middle fraction and the heavy fraction are mixed in a mass ratio of 1:3 as the raw material of this embodiment.

[0060] Table 1 Properties of raw materials (hydrogenated stabilized liquefied oil)

[0061]

[0062]

[0063] The hydrogenation reaction conditions of this embodiment are shown in Table 2, wherein the pre-hydrogenation reactor (coal liquefaction hydrogenation step) is filled with commercial pre-hydrogenation protective agent RGC-1, and the upgrading reactor (hydrogenation refining step) is filled with the catalyst MoO / A1SBA-15 of the present invention.

[0064] Table 2 Example 1 Hydrogenation Experiment Conditions

[0065]

[0066] Basic properties of lubricant base oil components:

[0067] The properties of the lubricating base oil components of the liquefied oil after hydrogenation are shown in Table 3, and a typical lubricating base oil 150SN base oil is added as a comparison.

[0068] Table 3 Properties of lubricating oil base oil components after hydrogenation modification in Example

[0069]

[0070] As can be seen from Table 3, the present invention can effectively utilize the coal liquefaction oil fraction to prepare a lubricating oil base oil with better quality, especially compared with the existing typical lubricating oil base 150SN; the oil product obtained by using the hydrogenation catalyst of the present invention has a lower sulfur content and nitrogen content, and a lower viscosity index and kinematic viscosity, and can replace 150SN and be widely used in the fields of industrial lubrication to metal processing.

[0071] Comparative Example 1:

[0072] The difference from Example 1 is that the catalyst is different. Comparative Example 1 uses a commercially available industrial catalyst, the properties of the catalyst are shown in Table 4, and the reaction conditions refer to Table 5.

[0073] Table 4 Main properties of commercial catalyst RNC-2

[0074] project RNC-2 Chemical composition (w), % NiO ≮2.6 <![CDATA[MoO3]]> ≮2.3 <![CDATA[WO3]]> ≮25.0

[0075] Table 5 Comparative Example Hydrogenation Experiment Conditions

[0076]

[0077] Basic properties of lubricant base oil components:

[0078] The properties of the liquefied oil lubricant base oil components after hydrogenation are shown in Table 6.

[0079] Table 6 Properties of lubricating oil base oil components after hydro-modification in comparative examples

[0080]

[0081] From the above-mentioned Example 1 and Comparative Example 1, it can be seen that the present invention can effectively use coal liquefaction oil fractions to prepare lubricating oil base oils with better quality, especially compared with the existing typical lubricating oil base 150SN; the oil product obtained by using the hydrogenation catalyst of the present invention has low sulfur content and nitrogen content, low viscosity index and low kinematic viscosity, and can replace 150SN and be widely used in fields such as industrial lubrication and metal processing. From the implementation effect of the comparative example, it can be seen that the catalyst used in the present invention has significant low-temperature hydrorefining performance, the product S and N content is much lower than that of commercial catalysts under the same reaction conditions, and the indicators such as oxidation stability are also better than those of Comparative Example 1.

[0082] In summary, the method for producing lubricating base oil from coal liquefied oil proposed in the present invention, and the coal liquefied oil heavy oil after hydrogenation stabilization to make lubricating base oil have the following significant advantages: (1) Through hydrogenation treatment, impurities in coal liquefied oil and heavy oil, such as sulfur, nitrogen, oxygen, etc., can be effectively removed. These impurities in lubricating oil will affect its performance and stability. (2) The base oil obtained after hydrogenation treatment has higher purity and significantly reduced impurity content. (3) Excellent low-temperature performance: Hydrogenation treatment makes the olefin and aromatic components in the base oil saturated to form more saturated hydrocarbon substances. These saturated hydrocarbons have good low-temperature performance, so that the lubricating oil can still maintain good fluidity and lubrication performance under low temperature environment. (4) Improved oxidation stability: Hydrogenation treatment improves the antioxidant properties of the base oil, making the lubricating oil more stable at high temperature, not easy to oxidize and deteriorate, thereby extending the service life of the lubricating oil. This is particularly important for mechanical equipment that needs to work for a long time and operate at high temperature. (5) Environmental friendliness: Hydrogenation treatment reduces the sulfur content in the base oil, reduces the sulfur oxide emissions after the lubricating oil is burned, and is more environmentally friendly. This helps meet increasingly stringent environmental regulations. (6) Improved lubrication performance: Hydrotreated base oils have a better viscosity index and lower volatility. These properties can improve the overall lubrication performance of the lubricant, enabling it to provide reliable lubrication protection under different working conditions.

[0083] In general, lubricant base oil made from hydrogenated coal liquefaction heavy oil shows significant advantages in purity, performance and environmental protection, and can meet the needs of modern industry for high-performance lubricants.

[0084] Parts not described in the present invention can be implemented by those skilled in the art by referring to the existing technology.

[0085] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A method for producing lubricating base oil from coal liquefaction oil, characterized in that: The method comprises the following steps: S1, using coal liquefaction hydrogenation stabilized oil as raw oil, fractionating the raw oil at 200-230°C and 400-430°C, and obtaining a liquefied oil middle fraction and a heavy fraction through fractionation; S2, mixing the middle fraction and the heavy fraction in a certain proportion; S3, performing hydrofining on the mixed fraction obtained in S2, wherein the hydrogenation catalyst used in the hydrofining is prepared by using modified Al-SBA-15 as a carrier and loading active metal Mo by an impregnation method; S4. The hydrorefined material is subjected to hydrodewaxing and product fractionation to obtain lubricating base oil.

2. The method for producing lubricating base oil from coal liquefaction oil according to claim 1, characterized in that: In step S2, the middle fraction and the heavy fraction are mixed according to mass percentages of 10-30% and 70-90%.

3. The method for producing lubricating base oil from coal liquefaction oil according to claim 1, characterized in that: In step S3, the hydrotreating is carried out in a fixed reaction bed, the reaction pressure is 9-11 MPa, the reaction temperature is 310-340°C, and the liquid hourly space velocity is 0.6-1.2 h -1 .

4. The method for producing lubricating base oil from coal liquefaction oil according to claim 1, characterized in that: In step S3, the loading amount of the active metal is 5-20% based on the weight of the hydrogenation catalyst.

5. The method for producing lubricating base oil from coal liquefaction oil according to claim 1, characterized in that: In step S3, the preparation steps of the hydrogenation catalyst are: Preparation of a carrier: including preparation of an aluminum source, preparation of a template solution, mixing and acidification steps to obtain an HCl-modified Al-SBA-15 carrier; Loading: impregnating the HCl-modified Al-SBA-15 carrier with the ammonium molybdate solution by an equal volume method, and mixing the two uniformly by stirring and shaking to obtain an impregnated mixture; Drying treatment: Dry the impregnated mixture to remove moisture; Calcination activation: The sample obtained after drying is calcined at a certain temperature. During the calcination process, ammonium molybdate decomposes to form MoO3, which is firmly attached to the modified Al-SBA-15 carrier.

6. The method for producing lubricating base oil from coal liquefaction oil according to claim 5, characterized in that: The preparation steps of the aluminum source are: The aluminum isopropoxide is dried, and a dispersant is added to the dried aluminum isopropoxide to ensure that the aluminum isopropoxide particles are evenly dispersed; the evenly dispersed aluminum isopropoxide is then placed in a ball mill for crushing treatment, so that the crushed particle size is uniform and the particle size reaches the nanometer level; the aluminum isopropoxide after the ball milling treatment is dispersed in anhydrous ethanol for ultrasonic treatment; the ethanol in the aluminum isopropoxide solution after ultrasonic dispersion is evaporated, and the obtained aluminum isopropoxide is dried to obtain the treated aluminum isopropoxide powder as an aluminum source.

7. The method for producing lubricating base oil from coal liquefaction oil according to claim 6, characterized in that: The template solution is prepared by adding a certain amount of triblock copolymer P123 into anhydrous ethanol for dissolution, wherein the mass ratio of the triblock copolymer P123 to the anhydrous ethanol is 1:5-10.

8. The method for producing lubricating base oil from coal liquefaction oil according to claim 7, characterized in that: The mixing and acidification steps are as follows: adding a certain amount of ethyl silicate, treated aluminum isopropoxide powder and hydrochloric acid to the template solution for mixing and stirring, starting stirring and controlling the temperature during the acidification process with hydrochloric acid, and maintaining the acidification temperature at room temperature to 30°C; when the mixed solution is stirred until it becomes a light white translucent liquid, reacting for a period of time, covering the reaction mixture with a polyethylene film, and performing an aging treatment, and after drying and calcining, obtaining an HCl-modified Al-SBA-15 carrier.

9. The method for producing lubricating base oil from coal liquefaction oil according to claim 6, characterized in that: Aluminum isopropoxide is placed in a vacuum drying oven for drying, the set temperature is 90-110° C., and the drying time is 1-3 hours; the dispersant is one or two of sodium polyacrylate, polycarboxylate, lignin sulfonate, fatty acid polyethylene glycol ester, alkylphenol polyoxyethylene ether, polyvinyl pyrrolidone, and Tween; in terms of mass percentage, the dispersant accounts for 0.5-2% of the aluminum isopropoxide after drying.

10. The method for producing lubricating base oil from coal liquefaction oil according to claim 8, characterized in that: The molar ratio of hydrochloric acid to ethyl silicate is 0.1:1 to 1:1, the aging treatment temperature is 45 to 55°C, and the aging treatment time is 20 to 25 hours; the drying temperature after aging is 100 to 110°C, and the drying time is 6 to 9 hours; the roasting temperature is 450 to 550°C, and the roasting time is 3 to 5 hours.

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