Preparation method of lubricant base oil

Abstract

The invention provides a preparation method of lubricant base oil. The preparation method comprises the steps that Fischer-Tropsch hydrogenated heavy oil is subjected to a hydroisomerization reaction under the action of a hydroisomerization catalyst, a hydroisomerization product is obtained, and the mass content of isoparaffin in the hydroisomerization product is larger than 80%; the hydroisomerization product is subjected to hydrofining under the action of a hydrofining catalyst, a hydrofining product is obtained, and the mass content of isoparaffin in the hydrofining product is larger than 90%; carrying out atmospheric distillation on the hydrofining product to obtain tower top light components, isomerized gasoline, W-TB white oil and atmospheric tower kettle oil; cutting the atmospheric tower kettle oil under reduced pressure to obtain lubricating oil base oil and tower bottom heavy oil, and recycling the tower bottom heavy oil as a raw material of a hydroisomerization reaction. The lubricating oil base oil product prepared by the method is high in quality, low in pour cloud point and transparent in color.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating oil base oil processing, and in particular to a method for preparing lubricating oil base oil. Background Art

[0002] The invention relates to a lubricating oil base oil mainly produced from Fischer-Tropsch hydrogenated heavy oil and a high-efficiency utilization scheme.

[0003] my country's energy structure is rich in coal, less in oil, and poor in gas, which is different from my country's demand for petroleum products, resulting in an increase in my country's dependence on foreign oil and natural gas. In order to ensure my country's energy security and supply-demand relationship, my country has vigorously developed the coal chemical industry. Coal indirect liquefaction based on Fischer-Tropsch synthesis can not only effectively and cleanly utilize my country's abundant coal resources, but also ensure national energy security and provide other options for energy supply. Fischer-Tropsch hydrogenated heavy oil has the characteristics of low sulfur, nitrogen and aromatic content, high chain alkane content, and long carbon chain. The hydrogenation isomerization process is used to isomerize normal alkanes into branched alkanes for the preparation of lubricant base oils, providing a new solution for special lubricants.

[0004] Since the 21st century, the global lubricant market has seen a continuous increase in demand for API III lubricant base oils, and the requirements for the properties of lubricants have become increasingly stringent. my country's API III and IV base oil production capacity is relatively weak, and its external dependence is relatively high. There are physical and chemical methods for the production of lubricant base oils. Among them, the traditional three sets of lubricant base oil production processes (solvent refining, solvent dewaxing, and clay refining) use physical separation methods to remove non-ideal components to obtain lubricant base oils. This method has relatively high requirements for the properties of the raw oil. Chemical methods include: hydroisomerization, hydrocracking, hydrorefining, etc., which change the chain structure of hydrocarbons in the raw oil to transform non-ideal components into ideal components, thereby improving the performance of lubricant base oils. For the characteristics of high paraffin content and high saturation of Fischer-Tropsch synthetic oils, hydroisomerization can effectively isomerize the long-branched normal alkanes in its components into single-chain or multi-chain alkanes, and can produce lubricant base oils of better quality.

[0005] CN102533329A discloses a method for producing lubricating base oil from Fischer-Tropsch wax. The prior art method can appropriately improve the base oil yield by gradually slowing down the pour point through two isomerization reaction zones. However, since the Fischer-Tropsch wax contains a large amount of normal alkanes with a high carbon number, direct isomerization reaction will cause excessive cracking reaction, resulting in a decrease in the lubricating base oil yield and a decrease in the viscosity index. CN107760375A discloses a method for converting heavy Fischer-Tropsch wax, wherein the Fischer-Tropsch wax is divided into a light and heavy part according to the carbon 40 fraction, the heavy fraction is converted to light by hydrogenation treatment, and then mixed with the aforementioned light fraction, and hydrogenated together to obtain a base oil product with a wide fraction, which limits the later blending of lubricating oil. CN111690434A discloses a method for preparing lubricating oil base oil from Fischer-Tropsch wax, wherein the Fischer-Tropsch wax reacts with a hydrocracking catalyst, and a fraction of 370-430°C and a fraction greater than 430°C are separated by distillation, wherein the second fraction is wide, and the base oil yield is reduced, and in industrial production, it is difficult for the wide fraction raw material to directly produce a high-viscosity base oil (>500 fraction) with a qualified cloud point. CN1761734A discloses a method for preparing base oil from a Fischer-Tropsch synthesis product, wherein the Fischer-Tropsch full distillate is cut into different fraction sections: a fraction less than 370°C, a fraction of 370-540°C, and a fraction greater than 540°C. The method of the prior art can produce qualified lubricating oil base oil through multiple fractionation and hydrogenation conversion. The heavy tail oil fraction is subjected to hydrogenation conversion, fractionation, catalytic hydrogenation isomerization, and then catalytic dewaxing to produce base oil, and the process is complicated, which will result in a reduction in the yield of lubricating oil base oil and an increase in viscosity index loss.

[0006] At present, the patent for producing base oil using Fischer-Tropsch wax as raw material has the following main process routes: Fischer-Tropsch wax is treated by hydrocracking, and the whole fraction or cut fraction of the cracked tail oil is used as raw material, and the base oil is produced by isomerization dewaxing, supplementary refining and product cutting. In actual industrial production, it is difficult for the catalyst to achieve high base oil yield and performance when the whole fraction or wide fraction is fed, and the light fraction in the wide fraction is prone to cracking reaction to generate unsaturated hydrocarbons, resulting in high hydrogen consumption and increased production costs. At the same time, the properties of the base oil produced by the fraction feed are unstable, and floccules exist in the high-viscosity base oil. In addition, the process flow of refining first and then cutting, due to the high temperature of the atmospheric and vacuum tower kettle, is easy to cause thermal cracking of the oil product and the target product has color, and it needs to be refined again to ensure that the base oil product color is qualified, which increases production costs. Moreover, since these main reactions will have hydrocracking side reactions, the dry gas concentration in the product will increase, reducing the added value of the product. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for preparing a lubricating oil base oil, so as to solve the technical problems of the existence of floccules in high-viscosity base oil and the color of the product in the prior art.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a method for preparing a lubricating oil base oil, the preparation method comprising: subjecting Fischer-Tropsch hydrogenated heavy oil to a hydroisomerization reaction under the action of a hydroisomerization catalyst to obtain a hydroisomerization product, wherein the mass content of isoparaffins in the isomerization product is greater than 80%; subjecting the hydroisomerization product to a hydrorefining catalyst to a hydrorefining product to obtain a hydrorefining product, wherein the mass content of isoparaffins in the hydrorefining product is greater than 90%; subjecting the hydrorefining product to atmospheric distillation to obtain a light component at the top of a tower, isomerized gasoline, W-TB white oil and atmospheric tower bottom oil; subjecting the atmospheric tower bottom oil to a reduced pressure cutting to obtain a lubricating oil base oil and a tower bottom heavy oil, and recycling the tower bottom heavy oil as a raw material for a hydroisomerization reaction.

[0009] Further, the Fischer-Tropsch hydrogenated heavy oil includes any one or more of hydrofining reduced bottom oil, hydrocracking reduced bottom oil and hydrofining tail oil narrow fraction;

[0010] Preferably, the content of metal element impurities in the Fischer-Tropsch hydrogenated heavy oil is less than 20 ppm.

[0011] Further, the hydroisomerization catalyst comprises a molecular sieve support and a first active metal, the molecular sieve support comprises any one or more of SAPO-11, SAPO-31, ZSM-22, ZSM-23, ZSM-35, ZSM-48 and EU-1, and the first active metal comprises any one or more of Pt, Pd, Ni and W;

[0012] The temperature of the hydroisomerization reaction is 270-350°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , the hydrogen-oil ratio is (400~2000):1.

[0013] Further, the hydrotreating catalyst comprises a carrier and a second active metal, the carrier comprises any one or more of Al2O3, all-silicon molecular sieve, silicon oxide and graphite, and the second active metal is any one or more of Pt, Pd, Ni and W;

[0014] The temperature of the hydrorefining reaction is 200-300°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , hydrogen-oil ratio is (400-2000):1;

[0015] Preferably, the specific surface area of ​​the carrier is 160 m 2 / g-180m 2 / g, acid content is 0.3mmol·g -1 -0.5mmol·g -1 .

[0016] Further, the cutting temperature of the light components at the top of the tower is IBP-150°C, the cutting temperature of isomerized gasoline is 150-250°C, and the cutting temperature of W-TB white oil is 230-310°C;

[0017] The pressure of the reduced pressure cutting is 0.2KPa(G)-0.1KPa(G); 2cSt base oil, 3cSt base oil, 4cSt base oil and 6cSt base oil are obtained by reduced pressure cutting, the cutting temperature of 2cSt base oil is 310-380°C, the cutting temperature of 3cSt base oil is 370-410°C, the cutting temperature of 4cSt base oil is 410-450°C, and the cutting temperature of 6cSt base oil is 450-570°C;

[0018] Preferably, the cutting temperature of isomerized gasoline is 180°C-200°C;

[0019] Preferably, the cutting temperature of white oil is 230-300°C;

[0020] Preferably, the cutting temperature of 2cSt base oil is 300-370°C;

[0021] Preferably, the cutting temperature of 3cSt base oil is 390-410°C;

[0022] Preferably, the cutting temperature of 4cSt base oil is 410-445°C;

[0023] Preferably, the cutting temperature of 6 cSt base oil is 450-560°C.

[0024] Furthermore, the preparation method also includes: passing the light components at the top of the tower through a pressure swing adsorption unit to obtain hydrogen and dry gas; the dry gas and water vapor are converted into a first synthesis gas through a steam conversion unit; the synthesis gas is subjected to a medium-temperature conversion treatment to make the molar ratio of hydrogen to carbon monoxide 2-4:1 to obtain a second synthesis gas; and the second synthesis gas is subjected to a Fischer-Tropsch reaction to obtain a Fischer-Tropsch synthetic oil.

[0025] Further, the adsorbent of the pressure swing adsorption unit is any one or more of silica gel, activated alumina, activated carbon and molecular sieve;

[0026] The dry gas includes C1-C6 alkanes with a mass fraction of 2%-5% and H2 with a mass fraction of 95%-98%.

[0027] Further, the pressure of the steam reforming unit is 3.5-4 MPa and the temperature is 700-900°C;

[0028] Preferably, the catalyst used in the steam reforming unit includes any one or more of a pure alumina sintered catalyst, a magnesium oxide alumina sintered catalyst and a Ni / Al2O3 catalyst;

[0029] Preferably, the carbon ratio of the steam reforming unit is 3:1-5:1;

[0030] Preferably, the molar content of CO in the first synthesis gas is 15%-19%, the molar content of CO2 is 1%-5%, and the molar content of H2 is 20%-40%.

[0031] Further, the catalysts for the medium temperature shift treatment include iron-chromium, copper-zinc and cobalt-molybdenum catalysts;

[0032] The temperature of medium temperature shift treatment is 200-550℃ and the pressure is 2-4MPa;

[0033] In the second synthesis gas, the molar content of H2 is 50%-70%, the molar content of CO is 12%-18%, and the molar content of CO2 is 5%-10%.

[0034] Furthermore, the catalyst for Fischer-Tropsch synthesis is any one or more of an iron-based catalyst and a cobalt-based catalyst.

[0035] Preferably, the temperature of Fischer-Tropsch synthesis is 200-280°C and the pressure is 2.5-3.2 MPa.

[0036] By applying the technical solution of the present invention, the long-chain normal alkanes in the Fischer-Tropsch hydrogenated heavy oil are isomerized into single-chain or multi-chain alkanes through hydroisomerization reaction and hydrofining reaction, and further through specific atmospheric distillation and vacuum cutting methods, isomerized gasoline, W-TB white oil and lubricating oil base oil and other products are obtained, thereby achieving a more comprehensive utilization of the Fischer-Tropsch oil, and further improving the utilization rate of the raw material oil by refining the heavy oil at the bottom of the vacuum cutting tower. In addition, the lubricating oil base oil product prepared by the method of the present application has high quality, low pour cloud point, and bright color, especially the quality of high-viscosity base oil is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 A schematic diagram of the process flow of a method for preparing a lubricating oil base oil according to Example 1 of the present invention is shown.

[0039] Among them, the above drawings include the following figure marks: 01, hydroisomerization reactor; 02, hydrorefining reactor; 03, atmospheric pressure tower; 04, vacuum tower; 05, pressure swing adsorption unit; 06, steam conversion unit; 07, medium temperature shift reactor; 08, Fischer-Tropsch reactor. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] As analyzed in the background technology of this application, the prior art has the technical problems of floccules and colored products in high-viscosity base oil. In order to solve this problem, this application provides a method for preparing lubricating oil base oil, which comprises: subjecting Fischer-Tropsch hydrogenated heavy oil to a hydroisomerization reaction under the action of a hydroisomerization catalyst to obtain a hydroisomerization product, wherein the mass content of isoparaffins in the isomerization product is greater than 80%; subjecting the hydroisomerization product to a hydrorefining catalyst to a hydrorefining product, wherein the mass content of isoparaffins in the hydrorefining product is greater than 90%; subjecting the hydrorefining product to atmospheric distillation to obtain a light component at the top of the tower, isomerized gasoline, W-TB white oil and atmospheric tower bottom oil; subjecting the atmospheric tower bottom oil to a reduced pressure cutting to obtain a lubricating oil base oil and a tower bottom heavy oil, and recycling the tower bottom heavy oil as a raw material for the hydroisomerization reaction.

[0042] The preparation method of the lubricating oil base oil of the present application isomerizes the long-chain normal alkanes in the Fischer-Tropsch hydrogenated heavy oil into single-chain or multi-chain alkanes through hydrogenation isomerization reaction and hydrofining reaction, and further obtains isomerized gasoline, W-TB white oil and lubricating oil base oil and other products through specific atmospheric distillation and vacuum cutting methods, thereby achieving a more comprehensive utilization of the Fischer-Tropsch oil, and further improving the utilization rate of the raw material oil by refining the heavy oil at the bottom of the vacuum cutting tower. Not only that, the lubricating oil base oil product prepared by the method of the present application has high quality, low pour cloud point, and bright color, especially the quality of high-viscosity base oil is significantly improved.

[0043] In some embodiments of the present application, the Fischer-Tropsch hydrogenated heavy oil includes any one or more of hydrofining reduced bottom oil, hydrocracking reduced bottom oil and hydrofining tail oil narrow fraction; preferably, the content of metal element impurities in the Fischer-Tropsch hydrogenated heavy oil is less than 20 ppm.

[0044] In some embodiments of the present application, the Fischer-Tropsch hydrogenated heavy oil is a heavy oil with a final boiling point of >500°C.

[0045] The above hydroisomerization catalyst can be selected from the prior art. In some embodiments of the present application, the hydroisomerization catalyst includes a molecular sieve carrier and a first active metal, the molecular sieve carrier includes any one or more of SAPO-11, SAPO-31, ZSM-22, ZSM-23, ZSM-35, ZSM-48 and EU-1, and the first active metal includes any one or more of Pt, Pd, Ni and W; the hydroisomerization catalyst having the above molecular sieve carrier and active metal has a good hydroisomerization effect, especially based on the Fischer-Tropsch hydrogenated heavy oil of the present application, the catalytic effect of isomerizing the long-branched normal alkanes into single-side chain or multi-side chain alkanes is better, which helps to produce lubricating oil base oil with better quality.

[0046] In some embodiments of the present application, the temperature of the hydroisomerization reaction is 270-350°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , the hydrogen-oil ratio is (400~2000):1.

[0047] In some embodiments of the present application, in the hydroisomerization product, the mass content of normal alkanes is less than 10%, the mass content of isoalkanes is greater than 80%, and the mass content of unsaturated hydrocarbons (such as olefins) is less than 10%.

[0048] The above-mentioned hydrofining catalyst can be selected from the prior art. In some embodiments of the present application, the hydrofining catalyst includes a carrier and a second active metal, the carrier includes any one or more of Al2O3, all-silicon molecular sieve, silicon oxide and graphite, and the second active metal is any one or more of Pt, Pd, Ni and W; the hydrofining effect is better. In some embodiments, the specific surface area of ​​the carrier is 160m 2 / g-180m 2 / g, acid content is 0.3mmol·g -1 -0.5mmol·g -1 .

[0049] In some embodiments of the present application, the temperature of the hydrofining reaction is 200-300°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , the hydrogen-oil ratio is (400~2000):1.

[0050] In some embodiments of the present application, in the hydrorefined product, the normal alkane content is less than 10%, and the isoalkane content is greater than 90%.

[0051] The present application obtains overhead light components, isomerized gasoline, W-TB white oil and atmospheric bottom oil by atmospheric distillation. In some embodiments of the present application, the cutting temperature of the overhead light components is IBP (initial boiling point) -150°C, the cutting temperature of isomerized gasoline is 150-250°C, and the cutting temperature of W-TB white oil is 230-310°C; the present application obtains isomerized gasoline by atmospheric distillation cutting, further improving the economic value of Fischer-Tropsch hydrogenated heavy oil.

[0052] In some embodiments of the present application, in order to further improve the quality of isomerized gasoline, the cutting temperature of isomerized gasoline is 180° C.-200° C. Those skilled in the art can understand that after the isomerized gasoline is cut at the above temperature, white oil can be cut out from the remaining components.

[0053] In some embodiments of the present application, in order to further improve the quality of white oil, the cutting temperature of white oil is 230-300°C.

[0054] In some embodiments of the present application, the process parameters of the atmospheric distillation include: a tower top temperature of 100-160°C, a tower bottom temperature of 300-320°C, a theoretical number of plates of 50, a saturated feed method, feed from the middle of the tower, and an operating reflux ratio of 4 / 1-2 / 1.

[0055] The atmospheric tower bottom oil obtained by the atmospheric distillation is subjected to reduced pressure cutting to obtain lubricating oil base oil and tower bottom heavy oil, and the tower bottom heavy oil is recycled as a raw material for hydroisomerization reaction.

[0056] In some embodiments of the present application, the pressure of the decompression cutting is 0.2 KPa (G) - 0.1 KPa (G).

[0057] In some embodiments of the present application, 2cSt base oil, 3cSt base oil, 4cSt base oil, and 6cSt base oil are obtained by vacuum cutting, and the cutting temperature of 2cSt base oil is 310-380° C., the cutting temperature of 3cSt base oil is 370-410° C., the cutting temperature of 4cSt base oil is 410-450° C., and the cutting temperature of 6cSt base oil is 450-570° C. The cutting temperature during vacuum cutting is not specifically stated, and is the distillation temperature corresponding to normal pressure.

[0058] In some embodiments of the present application, in order to further improve the quality of the 2cSt base oil, the cutting temperature of the 2cSt base oil is 300-370°C.

[0059] In some embodiments of the present application, in order to further improve the quality of 3 cSt base oil, the cutting temperature of 3 cSt base oil is 390-410°C.

[0060] In some embodiments of the present application, in order to further improve the quality of 4 cSt base oil, the cutting temperature of 4 cSt base oil is 410-445°C.

[0061] In some embodiments of the present application, in order to further improve the quality of 6 cSt base oil, the cutting temperature of 6 cSt base oil is 450-560°C.

[0062] Those skilled in the art will appreciate that in order to improve the quality of one or more oil products obtained by reduced pressure cutting, this can be achieved by balancing the cutting temperature of the oil products cut adjacent to the oil products.

[0063] In some typical embodiments of the present application, the above-mentioned preparation method also includes: passing the light components at the top of the tower through a pressure swing adsorption unit to obtain hydrogen and dry gas; the dry gas and water vapor are converted into a first synthesis gas through a steam conversion unit; the synthesis gas is subjected to a medium-temperature conversion treatment to make the molar ratio of carbon monoxide and hydrogen 2-4 to obtain a second synthesis gas; the second synthesis gas is subjected to a Fischer-Tropsch reaction to obtain a Fischer-Tropsch synthetic oil.

[0064] The above method converts the light components at the top of the tower into synthesis gas with an appropriate proportion through a pressure swing adsorption unit, a steam conversion unit, and a medium-temperature conversion process, and then performs a Fischer-Tropsch reaction to prepare Fischer-Tropsch synthetic oil. The recovery and treatment of the light components at the top of the tower by the above method further improves the raw material utilization rate and the added value of the product, ensuring that the oil is fully utilized.

[0065] The hydrogen and small molecule alkanes (i.e. dry gas) in the light components at the top of the tower are separated by pressure swing adsorption. The separated hydrogen can be used in hydrogenation isomerization reaction or hydrogenation refining process.

[0066] In some embodiments of the present application, the adsorbent of the pressure swing adsorption unit is any one or more of silica gel, activated alumina, activated carbon and molecular sieve.

[0067] In some embodiments of the present application, the dry gas comprises 2%-5% by mass of C1-C6 alkanes and 95%-98% by mass of H2.

[0068] In the steam reforming unit, the dry gas separated in the previous step reacts with water vapor to be converted into CO, CO2, and H2, i.e., the first synthesis gas. The main reactions that occur are as follows:

[0069] CH4+H2O=CO+3H2;

[0070] CH4+2H2O=CO2+4H2;

[0071] CH4+CO2=2CO+2H2;

[0072] CH4+2CO2=3CO+H2+H2O;

[0073] CH4+3CO2=4CO+2H2O;

[0074] CO+H2O=CO2+H2.

[0075] In addition, the reaction process may be accompanied by some side reactions, such as:

[0076] CH4=C+2H2;

[0077] 2CO=C+CO2;

[0078] CO+H2=C+2H2O.

[0079] In some embodiments of the present application, in order to improve the efficiency of the steam conversion unit and reduce the occurrence of side reactions, the pressure of the steam conversion unit is 3.5-4 MPa, and the temperature is 700-900°C, preferably 750-800°C.

[0080] In some embodiments of the present application, the water-to-carbon ratio in the steam conversion unit is 3:1-5:1, wherein the water-to-carbon ratio represents the ratio of the number of carbon atoms in water vapor to that in dry gas, i.e., H2O / C. Specifically, the carbon ratio in the steam conversion unit may be 3:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.7:1, 4.9:1, etc., and may also be other values ​​within the above range.

[0081] In some embodiments of the present application, the catalyst used in the steam conversion unit includes any one or more of a pure alumina sintered catalyst, a magnesium oxide alumina sintered catalyst and a Ni / Al2O3 catalyst, which has a good catalytic effect on the steam conversion reaction, can effectively reduce the occurrence of side reactions and improve the conversion efficiency.

[0082] In some embodiments of the present application, the molar content of CO in the first synthesis gas is 15%-19%, the molar content of CO2 is 1%-5%, the molar content of H2 is 20%-40%, and the rest is unreacted dry gas.

[0083] Since the ratio of CO and H2 in the above-mentioned first synthesis gas is not suitable for direct Fischer-Tropsch synthesis reaction, medium-temperature conversion treatment is adopted to make the CO and H2O in the above-mentioned first synthesis gas react into CO2 and H2, thereby adjusting the H2 / CO ratio in the synthesis gas.

[0084] In some embodiments of the present application, the catalysts for medium-temperature conversion treatment include iron-chromium series (active main body Fe3O4), copper-zinc series (active main body Cu Mn2O4) and cobalt-molybdenum series (active components are mainly Co-Mo, and the carrier is MgO-Al2O3 with spinel structure) catalysts, which have better catalytic effect.

[0085] In some embodiments of the present application, the temperature of the medium temperature shift treatment is 200-550°C and the pressure is 2-4 MPa. Preferably, the temperature of the medium temperature shift treatment is 350-550°C.

[0086] In some preferred embodiments, in order to improve the yield of Fischer-Tropsch synthesis, the water in the obtained second synthesis gas after the medium temperature shift treatment is separated by pressurizing and cooling. Preferably, the water content of the second synthesis gas subjected to the Fischer-Tropsch synthesis reaction is ≤20ppm.

[0087] In some embodiments of the present application, in the second synthesis gas used for the Fischer-Tropsch reaction, the molar content of H2 is 50%-70%, the molar content of CO is 12%-18%, and the molar content of CO2 is 5%-10%.

[0088] The second synthesis gas obtained after the medium-temperature conversion treatment enters the Fischer-Tropsch reactor for Fischer-Tropsch reaction to synthesize liquid fuels mainly including gasoline, diesel, paraffin hydrocarbons, etc. The recombinant fraction generated after the Fischer-Tropsch synthesis reactor is Fischer-Tropsch heavy oil, realizing the process cycle.

[0089] The specific process parameters of Fischer-Tropsch synthesis can refer to the prior art, and there is no particular limitation in this application. For example, the temperature of Fischer-Tropsch synthesis is 200-280° C. and the pressure is 2.5-3.2 Mpa.

[0090] In some embodiments of the present application, the catalyst for Fischer-Tropsch synthesis is any one or more of an iron-based catalyst and a cobalt-based catalyst.

[0091] The beneficial effects that can be achieved by the present application will be further illustrated below in combination with embodiments and comparative examples.

[0092] Example 1

[0093] The raw material is 60# wax produced by the hydrorefining reduced oil narrow fraction produced by the oil processing unit in the 4 million tons / year coal indirect liquefaction project of Ningmei. The distillation range of the raw material is 350℃-560℃. Figure 1 The process flow shown is for preparing lubricating base oil and coupling with a Fischer-Tropsch reactor to prepare Fischer-Tropsch synthetic oil.

[0094] Hydroisomerization: The catalyst loaded in the hydroisomerization reactor 01 is Pt / ZSM-48. The raw materials are introduced into the hydroisomerization reactor 01 with a hydrogen partial pressure of 4 MPa, a hydrogen-to-oil ratio of 1000:1, and a volume space velocity of 1 h-1 The reaction temperature is 330°C. The obtained hydroisomerization product has a normal alkane content of 2.3%, an isoalkane content of 96.2% and an unsaturated hydrocarbon content of 1.5%.

[0095] Hydrofining: The catalyst loaded in the hydrofining reactor 02 is Pt / Al2O3. The hydrogenated isomerized product is introduced into the hydrofining reactor 02 with a hydrogen partial pressure of 4 MPa, a hydrogen-to-oil ratio of 1000:1, and a volume space velocity of 1 h -1 The reaction temperature is 250°C. The obtained hydrorefined oil has a normal alkane content of 2.9% and an isoalkane content of 97.1%.

[0096] Atmospheric distillation: The hydrofining product is subjected to atmospheric distillation cutting in atmospheric tower 03 to obtain light components at the top of the tower with a cutting temperature less than 150°C, isomerized gasoline, W-TB white oil and atmospheric tower bottom oil, wherein the yields of isomerized gasoline and W-TB white oil relative to the hydrogenation liquid phase product and the performance test results are shown in Table 1, wherein the light components at the top of the atmospheric tower account for about 10% of the refined oil product.

[0097] Vacuum cutting: The atmospheric tower bottom oil is vacuum cut in the vacuum tower 04, and the pressure of the vacuum cutting is 0.2KPa (G) to obtain 2cSt base oil, 3cSt base oil, 4cSt base oil, 6cSt base oil and tower bottom heavy oil. The tower bottom heavy oil is recycled, wherein the vacuum tower bottom heavy oil accounts for about 5% of the refined oil product. The yields of 2cSt base oil, 3cSt base oil, 4cSt base oil and 6cSt base oil and the performance test results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] Pressure swing adsorption: The light components at the top of the tower obtained by atmospheric distillation enter the pressure swing adsorption unit 05. The adsorbent used in the pressure swing adsorption unit 05 is activated alumina, and dry gas and hydrogen are obtained. The hydrogen is used in the hydroisomerization reaction and the hydrofining reaction.

[0102] Steam reforming: The dry gas is passed into the steam reforming unit 06. The catalyst used in the unit is a pure alumina sintered catalyst with a water-to-carbon ratio of 3.2. The pressure of the steam reforming unit is 3.6 MPa and the temperature is 800° C. The molar content of CO in the obtained first syngas is 19%, the molar content of CO2 is 4.5%, and the molar content of H2 is 36.5%.

[0103] Medium-temperature conversion: The first synthesis gas is introduced into the medium-temperature conversion reactor 07. The catalyst loaded in the medium-temperature conversion reactor 07 is an iron-chromium catalyst. The reaction temperature is 320°C and the pressure is 2Mpa. The product coming out of the medium-temperature conversion reactor is pressurized, cooled and dehydrated. The second synthesis gas obtained has a molar content of CO of 17%, a molar content of CO2 of 6.2%, a molar content of H2 of 65.2%, and a water content of 10ppm.

[0104] Fischer-Tropsch synthesis: The second synthesis gas is introduced into a Fischer-Tropsch reactor 8 filled with an iron-based catalyst for Fischer-Tropsch synthesis reaction at a temperature of 220° C. and a pressure of 2.7 MPa to obtain a Fischer-Tropsch synthesis oil C5+ product with a selectivity of 87.4%.

[0105] Comparative Example 1

[0106] The difference from Example 1 is that the fourth-line oil and the bottom oil of the tower are discharged from the device together, that is, the fraction after the 4 cSt base oil is used as the 6 cSt base oil to the final distillation point, and the heavy oil at the bottom of the vacuum tower is not recycled. The yield and performance of the obtained oil products are shown in Table 2 below.

[0107] Table 2

[0108]

[0109]

[0110] Example 2

[0111] The base oil lubricating oil was prepared using the same raw materials as in Example 1, and the specific steps were as follows:

[0112] Hydroisomerization: The catalyst loaded in the hydroisomerization reactor 01 is Pt / ZSM-22. The raw materials are introduced into the hydroisomerization reactor 01 with a hydrogen partial pressure of 10 MPa, a hydrogen-to-oil ratio of 1500:1, and a volume space velocity of 0.7 h -1 The reaction temperature was 325°C. The mass content of normal alkanes, isoalkanes and unsaturated hydrocarbons in the obtained hydrogenated isomerization product was 5.2%, 93.3% and 1.5%, respectively.

[0113] Hydrofining: The catalyst loaded in the hydrofining reactor 02 is Ni / Al2O3. The hydrogenated isomerized product is introduced into the hydrofining reactor 02 with a hydrogen partial pressure of 10 MPa, a hydrogen-to-oil ratio of 1500:1, and a volume space velocity of 0.7 h -1 The reaction temperature is 280°C, and the mass content of normal alkanes in the obtained hydrorefined oil is 5.2%, and the mass content of isoalkanes is 94.8%.

[0114] Atmospheric distillation: The hydrorefined product is subjected to atmospheric distillation cutting in atmospheric tower 03 to obtain light components at the top of the tower with a cutting temperature less than 150°C, isomerized gasoline, W-TB white oil and atmospheric tower bottom oil, wherein the yields of isomerized gasoline and W-TB white oil relative to the hydrogenation liquid phase product and the performance test results are shown in Table 3, wherein the light components at the top of the atmospheric tower account for about 10% of the refined oil product.

[0115] Vacuum cutting: The atmospheric tower bottom oil is vacuum cut in the vacuum tower 04, and the pressure of the vacuum cutting is 0.2 KPa (G) to obtain 2cSt base oil, 3cSt base oil, 4cSt base oil, 6cSt base oil and tower bottom heavy oil. The tower bottom heavy oil is recycled, wherein the vacuum tower bottom heavy oil accounts for about 5% of the refined oil product. The yields of 2cSt base oil, 3cSt base oil, 4cSt base oil and 6cSt base oil and the performance test results are shown in Table 3.

[0116] Table 3

[0117]

[0118]

[0119] Example 3

[0120] The difference from Example 1 is that the cutting temperature of isomerized gasoline and white oil in atmospheric cutting, and the cutting temperature in reduced pressure cutting, the cutting temperature of the oil products and the performance test results of the oil products are shown in Table 4. The light components at the top of the atmospheric tower account for about 13% of the refined oil products.

[0121] Table 4

[0122]

[0123] Example 4

[0124] The difference from Example 1 is that during the steam reforming process, the pressure of the steam reforming unit is 4 MPa and the temperature is 700° C. The molar content of CO in the obtained first synthesis gas is 7.9%, the molar content of CO2 is 10.4%, and the molar content of H2 is 30.8%.

[0125] Example 5

[0126] The difference from Example 1 is that during the medium temperature conversion process, the catalyst loaded is an iron-chromium catalyst, the reaction temperature is 450°C, the pressure is 3Mpa, and after removing water in the same manner as in Example 1, the molar content of CO in the obtained second synthesis gas is 15%, the molar content of CO2 is 7.2%, the molar content of H2 is 62.1%, and the water content is 30ppm. According to the same method as in Example 1, the selectivity of the obtained Fischer-Tropsch synthetic oil C5+ product is 75.1%.

[0127] Example 6

[0128] The difference from Example 1 is that the second synthesis gas obtained after the medium-temperature conversion is not dehydrated and is directly used for Fischer-Tropsch synthesis. The process of Fischer-Tropsch synthesis is the same as that of Example 1, and the selectivity of the obtained Fischer-Tropsch synthesis oil C5+ product is 80.4%.

[0129] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the above-mentioned method for preparing lubricating oil base oil isomerizes the long-chain normal alkanes in the Fischer-Tropsch hydrogenated heavy oil into single-chain or multi-chain alkanes through hydrogenation isomerization reaction and hydrogenation refining reaction, and further obtains isomerized gasoline, W-TB white oil and lubricating oil base oil and other products through specific atmospheric distillation and vacuum cutting methods, thereby achieving a more comprehensive utilization of Fischer-Tropsch oil, and further improving the utilization rate of raw material oil by refining the heavy oil at the bottom of the vacuum cutting tower. In addition, the lubricating oil base oil product prepared by the method of the present application has high quality, low pour cloud point, and bright color, especially the quality of high-viscosity base oil is significantly improved.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a lubricating oil base oil, characterized in that: include: Carrying out a hydroisomerization reaction on the Fischer-Tropsch hydrogenated heavy oil under the action of a hydroisomerization catalyst to obtain a hydroisomerization product, wherein the mass content of isoparaffins in the isomerization product is greater than 80%; The hydroisomerization product is subjected to hydrorefining under the action of a hydrorefining catalyst to obtain a hydrorefining product, wherein the mass content of isoparaffins in the hydrorefining product is greater than 90%; The hydrorefined product is subjected to atmospheric distillation to obtain overhead light components, isomerized gasoline, W-TB white oil and atmospheric bottom oil; The atmospheric tower bottom oil is subjected to reduced pressure cutting to obtain lubricating oil base oil and tower bottom heavy oil, and the tower bottom heavy oil is recycled as a raw material for the hydroisomerization reaction.

2. The method for preparing a lubricating oil base oil according to claim 1, characterized in that: The Fischer-Tropsch hydrogenated heavy oil includes any one or more of hydrofining reduced bottom oil, hydrocracking reduced bottom oil and hydrofining tail oil narrow fraction; Preferably, the content of metal element impurities in the Fischer-Tropsch hydrogenated heavy oil is less than 20 ppm.

3. The method for preparing a lubricating oil base oil according to claim 1, characterized in that: The hydroisomerization catalyst comprises a molecular sieve carrier and a first active metal, wherein the molecular sieve carrier comprises any one or more of SAPO-11, SAPO-31, ZSM-22, ZSM-23, ZSM-35, ZSM-48 and EU-1, and the first active metal comprises any one or more of Pt, Pd, Ni and W; The temperature of the hydroisomerization reaction is 270-350°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , the hydrogen-oil ratio is (400~2000):

1.

4. The method for preparing a lubricating oil base oil according to claim 1, characterized in that: The hydrotreating catalyst comprises a carrier and a second active metal, wherein the carrier comprises any one or more of Al2O3, all-silicon molecular sieve, silicon oxide and graphite, and the second active metal is any one or more of Pt, Pd, Ni and W; The temperature of the hydrofining reaction is 200-300°C, the hydrogen pressure is 3-17 MPa, and the volume space velocity is 0.2-3 h -1 , hydrogen-oil ratio is (400-2000):1; Preferably, the specific surface area of ​​the carrier is 160 m 2 / g-180m 2 / g, acid content is 0.3mmol·g -1 -0.5mmol·g -1 .

5. The method for preparing a lubricating oil base oil according to claim 1, characterized in that: The cutting temperature of the light component at the top of the tower is IBP-150°C, the cutting temperature of the isomerized gasoline is 150-250°C, and the cutting temperature of the W-TB white oil is 230-310°C; The pressure of the reduced pressure cutting is 0.2KPa(G)-0.1KPa(G); 2cSt base oil, 3cSt base oil, 4cSt base oil and 6cSt base oil are obtained by reduced pressure cutting, the cutting temperature of the 2cSt base oil is 310-380°C, the cutting temperature of the 3cSt base oil is 370-410°C, the cutting temperature of the 4cSt base oil is 410-450°C, and the cutting temperature of the 6cSt base oil is 450-570°C; Preferably, the cutting temperature of the isomerized gasoline is 180°C-200°C; Preferably, the cutting temperature of the white oil is 230-300°C; Preferably, the cutting temperature of the 2cSt base oil is 300-370°C; Preferably, the cutting temperature of the 3cSt base oil is 390-410°C; Preferably, the cutting temperature of the 4cSt base oil is 410-445°C; Preferably, the cutting temperature of the 6cSt base oil is 450-560°C.

6. The method for preparing a lubricating oil base oil according to claim 1, characterized in that: The preparation method further comprises: The light component at the top of the tower is passed through a pressure swing adsorption unit to obtain hydrogen and dry gas; The dry gas and water vapor are converted into a first synthesis gas through a water vapor reforming unit; The synthesis gas is subjected to medium temperature shift treatment to make the molar ratio of hydrogen to carbon monoxide be 2-4:1 to obtain a second synthesis gas; The second synthesis gas is subjected to Fischer-Tropsch reaction to obtain Fischer-Tropsch synthesis oil.

7. The method for preparing a lubricating oil base oil according to claim 6, characterized in that: The adsorbent of the pressure swing adsorption unit is any one or more of silica gel, activated alumina, activated carbon and molecular sieve; The dry gas includes 2%-5% by mass of C1-C6 alkanes and 95%-98% by mass of H2.

8. The method for preparing a lubricating oil base oil according to claim 6, characterized in that: The pressure of the steam conversion unit is 3.5-4MPa and the temperature is 700-900°C; Preferably, the catalyst used in the steam reforming unit includes any one or more of a pure alumina sintered catalyst, a magnesium oxide alumina sintered catalyst and a Ni / Al2O3 catalyst; Preferably, the carbon ratio of the steam reforming unit is 3:1-5:1; Preferably, the molar content of CO in the first synthesis gas is 15%-19%, and the molar content of CO2 is 1%-5%. The molar content of H2 is 20%-40%.

9. The method for preparing a lubricating oil base oil according to claim 6, characterized in that: The catalysts for the medium temperature shift treatment include iron-chromium, copper-zinc and cobalt-molybdenum catalysts; The medium temperature conversion treatment has a temperature of 200-550°C and a pressure of 2-4MPa; In the second synthesis gas, the molar content of H2 is 50%-70%, the molar content of CO is 12%-18%, and the molar content of CO2 is 5%-10%.

10. The method for preparing a lubricating oil base oil according to claim 6, characterized in that: The catalyst for Fischer-Tropsch synthesis is any one or more of an iron-based catalyst and a cobalt-based catalyst. Preferably, the temperature of the Fischer-Tropsch synthesis is 200-280°C and the pressure is 2.5-3.2Mpa.

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