API Group III base oil and its preparation method

Abstract

The present invention relates to the technical field of lubricant base oils, and specifically relates to an API-Class III lubricating oil and a preparation method thereof. An API-Class III base oil is characterized in that the base oil is obtained by sequentially passing a feedstock oil through a hydroisomerization fixed-bed reactor and a hydrorefining fixed-bed reactor, and then separating through a separation unit. A feedstock oil, the components of which include: 50-70 wt% of hydrocracked tail oil of Fischer-Tropsch wax, 20-40 wt% of petroleum-based hydrocracked tail oil, 5-15 wt% of Fischer-Tropsch wax. The feedstock oil undergoes hydroisomerization and hydrorefining reactions, and the obtained API-Class III base oil has a high viscosity index, a low pour point, a low cloud point, high oxidation stability and excellent low-temperature performance, and can be used as a high-quality lubricant base oil. The specific indicators of the base oil are as follows: the kinematic viscosity at 100 °C is 2.0-9.0 mm 2 / s, the viscosity index > 125, wherein, for the base oil with a kinematic viscosity above 4.0 mm 2 / s, the viscosity index ≥ 130, the pour point ≤ -10 °C, the cloud point ≤ 0 °C, the oxidation stability RBOT > 320 min, and the low-temperature fluidity CCS (-30 °C) < 4200 mPa·s.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricant base oils, and particularly relates to an API-III type lubricating oil and a preparation method thereof. Background Art

[0002] With the development of environmental protection and the machinery industry, more stringent requirements are put forward for lubricating oil products for various purposes, requiring lubricating oils to have properties such as high oxidation resistance, higher viscosity index, good low-temperature fluidity, excellent shear stability and cleanliness. Therefore, the demand for high-quality lubricant base oils is gradually increasing.

[0003] Viscosity index and pour point are important indicators for evaluating lubricant base oil products. The higher the viscosity index, the smaller the change in the viscosity of the base oil with temperature, and the better the stability of the lubrication function. The lower the pour point, the better the fluidity of the product at low temperatures, and it can meet the normal use under harsh conditions such as extremely cold environments. Polyalphaolefin (PAO, API-IV type oil) fully synthetic base oil can meet the requirements of high viscosity index and low pour point, and at the same time has higher oxidation stability. However, the cost of fully synthetic base oil is significantly higher, and the price does not have a competitive advantage. The performance of API-III type base oil after hydroisomerization treatment is close to that of fully synthetic base oil, but the price is significantly lower than that of fully synthetic base oil, and it can be produced in large quantities, having the advantages of low cost and high cost performance.

[0004] Fischer-Tropsch synthesis, abbreviated as F-T reaction, is a process for synthesizing liquid fuels and chemicals mainly composed of long-chain alkanes from syngas (CO and H2) as raw materials under the action of catalysts such as Fe-based and Co-based catalysts and appropriate reaction conditions. In the products of low-temperature Fischer-Tropsch synthesis, the wax-containing components, including soft wax of C20-C30 and hard wax of >C30, account for more than 40%. Its main component is straight-chain alkane, almost free of sulfur, nitrogen and aromatics, and can be used as the raw material oil for high-quality lubricant base oil. Through hydrocracking and hydroisomerization reactions, the low-temperature fluidity of the raw material oil is improved, and at the same time, the loss of viscosity index is avoided as much as possible, so as to convert it into high-quality lubricant base oil.

[0005] At present, the prior arts disclosed at home and abroad for preparing with Fischer-Tropsch wax as raw material are as follows. For example, US5834522 discloses a method for producing lubricating oil base oil with Fischer-Tropsch synthesis product as raw material. The Fischer-Tropsch synthesis product is hydroisomerized in a hydroisomerization reaction zone. After the produced oil is separated by distillation, the bottoms of the distillation column are dewaxed to obtain oil and non-oil fractions. US5882505 discloses a method for producing lubricating oil base oil by converting Fischer-Tropsch wax with a boiling point greater than 370 °C using a countercurrent reactor. The raw material contacts with a hydroisomerization catalyst in a fixed-bed reactor, and the reaction product contacts with a hydrodewaxing catalyst in at least one fixed-bed reactor to obtain the target product. Among them, the hydroisomerization reaction product and the hydrogen-containing gas flow in reverse. CN1688674 discloses a multi-step method for preparing heavy lubricating oil base oil from Fischer-Tropsch wax, which includes hydrodewaxing the wax in the first hydrodewaxing step to obtain an isomerization product of a partially dewaxed heavy base oil fraction, and then hydrodewaxing the heavy lubricating oil fraction in one or more successive hydrodewaxing steps to remove hydrocarbons below the heavy lubricating oil fraction to obtain heavy lubricating oil base oil. CN1703488 discloses a method for preparing fuel and lubricating oil base oil from Fischer-Tropsch wax, including (1) hydrodewaxing Fischer-Tropsch wax to prepare an isomerization product containing fuel and a partially hydrodewaxed base oil fraction, (2) separating these two fractions, (3) separating the partially hydrodewaxed base oil fraction into a heavy fraction and a lower boiling point fraction, (4) further hydrodewaxing the lower boiling point fraction and the heavy fraction respectively to prepare lubricating oil base oil including heavy lubricating oil base stock. CN101230290 discloses a method for producing solvent oil, lubricating oil base oil and heavy wax with Fischer-Tropsch wax. The whole fraction product obtained by converting the wax in the hydrofining zone is fractionated to obtain a solvent oil light fraction, and then the base oil fraction product is separated and then subjected to hydroisomerization conversion, and the remaining heavy fraction is directly hydrofined to obtain decolorized wax.

[0006] The disadvantages of the above prior arts in the hydroisomerization reaction process are as follows: when the raw material oil mainly composed of Fischer-Tropsch wax is fed, due to the wide carbon number distribution of Fischer-Tropsch wax itself and the presence of a certain amount of high-carbon number straight-chain alkanes, it is difficult to balance the high viscosity index and low pour point of API-III type base oil, and the light and heavy base oil components cannot meet the requirements of pour point and viscosity index at the same time. When the pour point of the heavy base oil component is qualified, the viscosity index loss of the light base oil component is relatively large, resulting in a significant decrease in the yield of high viscosity index base oil produced, and it is difficult to produce light base oil products with a viscosity index > 125; when the viscosity index of the light base oil component is qualified, the pour point of the heavy component is too high and cannot be used as a qualified lubricating oil base oil product.

[0007] It can be seen from this that it is still difficult to use Fischer-Tropsch wax to produce lubricating oil base oil with high viscosity index, low pour point, low cloud point, high oxidation stability and excellent low-temperature performance in the prior art. The current Fischer-Tropsch wax mainly relies on the hydrocracking process to produce high-quality gasoline and diesel products, and the industry has been exploring new technologies for the efficient conversion of Fischer-Tropsch wax into lubricating oil base oil. Summary of the Invention

[0008] Aiming at the defects of the prior art, the present invention proposes to first hydrocrack Fischer-Tropsch wax, and use the hydrocracked tail oil of Fischer-Tropsch wax, petroleum-based hydrocracked tail oil, and Fischer-Tropsch wax after compounding as raw material oil, and then carry out hydroisomerization, hydrorefining, and fractionation. The obtained API-III type base oil has high viscosity index, low pour point, low cloud point, high oxidation stability and excellent low-temperature performance, and can be used as high-quality lubricating oil base oil.

[0009] The present invention provides the following technical solutions:

[0010] In the first aspect, the present invention provides a raw material oil, and its components include:

[0011] 50-70 wt% of hydrocracked tail oil of Fischer-Tropsch wax

[0012] 20-40 wt% of petroleum-based hydrocracked tail oil

[0013] 5-15 wt% of Fischer-Tropsch wax;

[0014] Among them, the distillation cut temperature range of the hydrocracked tail oil of Fischer-Tropsch wax is 260-730 °C; further, the initial boiling point temperature range of the distillation cut is 260-290 °C, and the final boiling point temperature range is 700-730 °C.

[0015] Among them, the density of the hydrocracked tail oil of Fischer-Tropsch wax at 20 °C is 810-830 kg / m 3 , and the kinematic viscosity at 100 °C is 5.0-7.0 mm 2 / s, and the viscosity index is 180-220.

[0016] The hydrocracked tail oil of Fischer-Tropsch wax contains straight-chain and isoparaffins, and a considerable part of the straight-chain alkanes are isomerized. The molecular weight of the straight-chain alkanes is reduced on the basis of Fischer-Tropsch wax through hydrocracking. If the hydrocracked tail oil of Fischer-Tropsch wax is too little, the viscosity index of the obtained base oil is too low and the oxidation stability is not high enough; if the dosage of the hydrocracked tail oil of Fischer-Tropsch wax is too much, the pour point and cloud point of the API-III type base oil are high.

[0017] Among them, the distillation cut temperature range of the petroleum-based hydrocracked tail oil is 360-570 °C; further, the initial boiling point temperature range of the distillation cut is 360-380 °C, and the final boiling point temperature range is 550-570 °C.

[0018] Among them, the density of the petroleum-based hydrocracked tail oil at 20 °C is 830-840 kg / m 3 , and the kinematic viscosity at 100 °C is 4.0-6.0 mm 2 / s, and the viscosity index is 130-160.

[0019] The petroleum-based hydrocracked tail oil contains branched alkanes and cycloalkanes with high carbon numbers. Excessive use leads to too low viscosity index of API-III base oil products, especially light base oils, usually lower than 125; the supply of petroleum-based hydrocracked tail oil that can be used to produce category III base oils is relatively small, resulting in limited supply of global API-III base oil products. In particular, the viscosity index of heavy base oils is insufficient, the evaporation loss is too high, and the low-temperature fluidity is also affected. Therefore, appropriately increasing the usage amount of petroleum-based hydrocracked tail oil can increase the production capacity of API-III base oils.

[0020] Among them, the rectification cutting temperature range of the Fischer-Tropsch wax is 360-580 °C; further, the initial boiling point temperature range of the rectification cutting is 360-380 °C, and the final boiling point temperature range is 540-550 °C.

[0021] Among them, the density of the Fischer-Tropsch wax at 20 °C is 810-820 kg / m 3 , and the kinematic viscosity at 100 °C is 4.0-6.0 mm 2 / s, and the viscosity index is 150-210.

[0022] The Fischer-Tropsch wax is mainly composed of straight-chain alkanes and branched alkanes with carbon numbers greater than 20. Excessive use requires a higher temperature for hydroisomerization reaction, approaching the limit use temperature of commercial hydroisomerization catalysts, resulting in more cracking reactions. Eventually, there are too many light components such as naphtha, and the yield of API-III base oil obtained after separation is low. In addition, when the amount of Fischer-Tropsch wax used is too much, the pour point and cloud point of the obtained API-III base oil are higher, and the low-temperature fluidity is reduced. Too little amount of Fischer-Tropsch wax leads to too low viscosity index of API-III base oil products, especially light base oils with a kinematic viscosity of 2.0-4.0 mm 2 / s, usually lower than 125.

[0023] Among them, the density of the feedstock oil at 20 °C is 820-840 kg / m 3 , preferably 830-840 kg / m 3 ; the kinematic viscosity at 100 °C is 4.0-6.0 mm 2 / s, preferably 5.0-6.0 mm 2 / s; the viscosity index is 150-210, preferably 155-185.

[0024] In a second aspect, a method for preparing API Group III base oil includes: sequentially passing the above raw material oil through a hydroisomerization fixed-bed reactor and a hydrorefining fixed-bed reactor, and then separating through a separation unit to obtain API Group III base oils with different kinematic viscosities.

[0025] Among them, the separation unit includes: a debutanizer, an atmospheric distillation column, and a vacuum distillation column.

[0026] Among them, the hydroisomerization catalyst and the hydrorefining catalyst are respectively loaded in the hydroisomerization fixed-bed reactor and the hydrorefining fixed-bed reactor.

[0027] Furthermore, the hydroisomerization catalyst can be obtained commercially, can be prepared according to the prior art, or the two can be used in combination.

[0028] Among them, the hydroisomerization catalyst includes a carrier and a hydroisomerization component loaded on the carrier; the carrier includes an inorganic porous material and a binder. Preferably, the inorganic porous material is a molecular sieve, and the binder is alumina and / or silica; the hydroisomerization component is a noble metal element, preferably Pt and / or Pd. Preferably, the mass ratio of the hydroisomerization component to the carrier is 0.1 - 0.5%. More preferably, the mass ratio of the hydroisomerization component to the carrier is 0.3%.

[0029] Preferably, the model of the commercially available hydroisomerization catalyst is one or a combination of more than one of RDW-1, SLD-800, SLD-821, SLD-861, ICR-400, ICR-404, or ICR-408.

[0030] Furthermore, the hydrorefining catalyst can be obtained commercially, can be prepared according to the prior art, or the two can be used in combination.

[0031] Among them, the hydrorefining catalyst includes a carrier, an active component, a promoter, and an optional carrier modifier. The carrier is alumina and / or silica-alumina; the active component is selected from at least one of Group VIII and Group VIB metal elements; the promoter is selected from at least one of Group IA and Group IIA elements; the carrier modifier is selected from at least one of Ce, Zr, Ti, and Si.

[0032] Preferably, the model of the commercially available hydrorefining catalyst is one or a combination of more than one of LN-5, LN-6, RLF-10, or ICR-407.

[0033] Among them, in the hydroisomerization reaction, the feeding rate of the raw material oil is 250 - 300 g / h, preferably 290 g / h, and the hydrogen-oil ratio is 1000 - 1500 m 3 / t, preferably 1200 m 3 / t, the newly introduced hydrogen gas amount is 300 - 500 L / h, preferably 400 L / h, the reaction temperature is 320 - 360 °C, preferably 330 - 355 °C, the reaction pressure is 13 - 15 MPa, the volume space velocity is 1.2 - 2.0 / h, preferably 1.3 / h.

[0034] Among them, for the hydrofining reaction, the feeding rate of the feedstock oil is 250 - 300 g / h, preferably 290 g / h, and the hydrogen-oil ratio is 1000 - 1500 m 3 / t, preferably 1200 m 3 / t, the newly introduced hydrogen gas amount is 300 - 500 L / h, preferably 400 L / h, the reaction temperature is 220 - 280 °C, preferably 240 °C, the reaction pressure is 13 - 15 MPa, the volume space velocity is 1.2 - 2.0 / h, preferably 1.8 / h.

[0035] In the third aspect, an API-Class III base oil prepared by using the above method, the kinematic viscosity of the base oil at 100 °C is 2.0 - 9.0 mm 2 / s, the viscosity index is greater than 125. Among them, the viscosity index of the base oil with a kinematic viscosity above 4.0 mm 2 / s is greater than or equal to 130, the pour point is less than or equal to -10 °C, the cloud point is less than or equal to 0 °C, the oxidation stability RBOT is greater than 320 min, and the low-temperature fluidity CCS is less than 4200 mPa·s at -30 °C.

[0036] The technical solution of the present invention has achieved the following beneficial effects:

[0037] First, hydrocrack the Fischer-Tropsch wax, and obtain a feedstock oil with a higher viscosity index by rectifying and cutting the hydrocracked tail oil of the Fischer-Tropsch wax and blending it with the petroleum-based hydrocracked tail oil and the Fischer-Tropsch wax. Subsequently, carry out hydroisomerization and hydrofining reactions on the feedstock oil, thereby obtaining an API-Class III base oil with a kinematic viscosity at 100 °C of 2.0 - 9.0 mm 2 / s, the viscosity index > 125. Among them, the viscosity index of the base oil with a viscosity above 4.0 mm 2 / s is ≥ 130, the pour point ≤ -10 °C, the cloud point ≤ 0 °C, the oxidation stability RBOT > 320 min, the low-temperature fluidity CCS (-30 °C) < 4200 mPa·s, and it can be used as a high-quality lubricating oil base oil. Compared with the prior art, the preparation method of the present invention can take into account the viscosity index, pour point and cloud point of the API-Class III base oil, and the base oil also has higher oxidation stability and low-temperature fluidity. At the same time, the obtained base oil has a clear and transparent appearance, no turbidity and no insoluble flocculent impurities. Specific embodiments

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe in detail the embodiments of the present invention in combination with specific examples. It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for this application. Unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0039] Feedstock oils for hydroisomerization and hydrorefining:

[0040] Petroleum-based hydrocracked tail oil, with a yellow solid appearance, a kinematic viscosity of 4.94 mm 2 / s at 100 °C and a kinematic viscosity of 22.76 mm 2 / s at 40 °C, a viscosity index of 148, and a density of 836.8 kg / m 3 (at 20 °C). Among them, the distillation range data of the petroleum-based hydrocracked tail oil obtained by fractional distillation are as follows:

[0041]

[0042] Coal-based Fischer-Tropsch wax, with a light yellow solid appearance, a kinematic viscosity of 4.48 mm 2 / s at 100 °C and a kinematic viscosity of 16.52 mm 2 / s at 40 °C, a viscosity index of 203, and a density of 815.3 kg / m 3 (at 20 °C). Among them, the distillation range data of the coal-based Fischer-Tropsch wax obtained by fractional distillation are as follows:

[0043] Initial boiling point 5％ 10％ 20％ 30％ 40％ 50％ 60％ 70％ 80％ 90％ Final boiling point Coal-based Fischer-Tropsch wax 362 396 413 432 443 454 462 468 475 482 491 524

[0044] Coal-based Fischer-Tropsch wax hydrocracked tail oil, obtained by subjecting the above-mentioned coal-based Fischer-Tropsch wax to a hydrocracking reaction and performing fractional distillation. Among them, the cracked product data obtained by fractional distillation are as described in the following table:

[0045]

[0046]

[0047]

[0048] Based on the above-mentioned coal-based Fischer-Tropsch wax hydrocracked tail oil, petroleum-based hydrocracked tail oil and coal-based Fischer-Tropsch wax are added as feedstock oils for the hydroisomerization and hydrorefining reactions.

[0049] Component of the feedstock oil in Example 1: 60 wt% of coal-based Fischer-Tropsch wax hydrocracked tail oil + 30 wt% of petroleum-based hydrocracked tail oil + 10 wt% of coal-based Fischer-Tropsch wax.

[0050] Feedstock oil components of Example 2: 25 wt% of coal-based Fischer-Tropsch wax hydrocracking tail oil + 35 wt% of petroleum-based hydrocracking tail oil + 10 wt% of coal-based Fischer-Tropsch wax.

[0051] Feedstock oil components of Example 3: 36.5 wt% of coal-based Fischer-Tropsch wax hydrocracking tail oil + 25 wt% of petroleum-based hydrocracking tail oil + 10 wt% of coal-based Fischer-Tropsch wax.

[0052] Feedstock oil components of the comparative example: 90 wt% of petroleum-based hydrocracking tail oil + 10 wt% of coal-based Fischer-Tropsch wax.

[0053] Commercially available base oil: S-OIL "aramco ULTRA" series API Group-III base oil, including base oils with different kinematic viscosities of 2 mm² / s, 4 mm² / s, and 6 mm² / s at 100 °C. 2 / s, 4 mm 2 / s, 6 mm 2 / s at 100 °C.

[0054] Among them, the specific steps of hydroisomerization and hydrorefining in Examples 1-3 and Comparative Example 1 are as follows:

[0055] S1. Contact the feedstock oil with a hydroisomerization catalyst to carry out a hydroisomerization reaction to obtain hydroisomerized oil;

[0056] S2. Contact the hydroisomerized oil with a hydrorefining catalyst to carry out a hydrorefining reaction to obtain hydrorefined oil;

[0057] S3. Separate the hydrorefined oil through a separation unit to obtain API Group-III base oil.

[0058] Among them, the indexes of the above-mentioned feedstock oil components are as follows.

[0059]

[0060] Among them, the process parameters of the above-mentioned hydroisomerization and hydrorefining reactions are as follows:

[0061]

[0062]

[0063] The product after the hydroisomerization and hydrorefining reactions enters the separation unit, and the separation unit includes: a debutanizer, a fractionating tower, and a vacuum tower.

[0064] The debutanizer has an operating pressure of 1.5 - 2.3 MPa, a bottom temperature of 200 - 240 °C, separates C4-hydrocarbons at the top, and collects the bottom material into the fractionating tower for atmospheric distillation.

[0065] The fractionating column has an operating pressure of 25 - 35 KPa, a bottom temperature of 330 - 360 °C. The naphtha separated at the top of the column contains C5 - C7. The material collected at the bottom of the column enters the vacuum tower for vacuum rectification.

[0066] The vacuum tower has an operating pressure of 4 - 10 KPa. API - III base oils of 2 mm 2 / s, 4 mm 2 / s, and 6 mm 2 / s are obtained from the first side line, the second side line, and the third side line respectively; the bottom product of the tower is 8 mm 2 / s of API - III base oil;

[0067] Among them, the discharge temperature of the first side line is 200 - 220 °C; the discharge temperature of the second side line is 260 - 280 °C, the discharge temperature of the third side line is 330 - 350 °C, and the discharge temperature of the bottom of the tower is 430 - 450 °C.

[0068] Among them, the preparation method of the self - made hydroisomerization catalyst is as follows:

[0069] The molar ratio of the phosphorus source calculated as P2O5, the aluminum source calculated as Al2O3, the silicon source calculated as SiO2, di - n - propylamine, di - isopropylamine, and water is 1:1.1:0.2:0.6:0.2:30. The dosage of the surfactant polyethylene glycol - 400 is 5.5 wt% of the dosage of the phosphorus source.

[0070] (1) At 25 °C, 270 g of deionized water and 230.59 g of concentrated phosphoric acid solution (phosphoric acid concentration is 85 wt%) are mixed, and then 7.8 g of polyethylene glycol - 400 is added thereto, and the mixture is stirred at a speed of 500 rpm for 40 min;

[0071] (2) 160.22 g of aluminum oxide monohydrate and 270 g of deionized water are mixed and slurried, and slowly added to the product of step (1), and the mixture is stirred at a speed of 800 rpm for 30 min;

[0072] (3) 40 g of basic silica sol (pH = 9.6, the effective content of SiO2 is 30 wt%) is added to the product obtained in step (2), and after stirring evenly, a mixed template agent of 60.7 g of di - n - propylamine and 20.24 g of di - isopropylamine is slowly added thereto, and the mixture is stirred at a speed of 800 rpm for 30 min to obtain a precursor gel;

[0073] (4) The precursor gel obtained in step (3) is poured into a paddle - type dynamic high - pressure crystallization kettle, crystallized at a constant temperature of 170 °C for 36 h, and the stirring speed is 600 rpm;

[0074] (5) Wash the product obtained in step (4) with deionized water, then dry it at 100 °C for 20 h and calcine it at 500 °C for 8 h to obtain molecular sieve. Grind the prepared molecular sieve into powder. The crystal grain size of the molecular sieve is between 0.1 - 1.0 μm. Conduct a nitrogen adsorption experiment at -196 °C to quantitatively analyze the BET surface area, external surface area and micropore volume of the prepared molecular sieve. The measured results are as follows:

[0075] <![CDATA[BET specific surface area (m 2 / g)]]> <![CDATA[External surface area (m 2 / g)]]> Micropore volume (mL / g) 266 83 0.084

[0076] (6) Weigh 25.5 g of the above molecular sieve powder and mix it with 45.5 g of aluminum oxide monohydrate. Add 11.5 g of citric acid solution (citric acid concentration is 5.2 wt%) as an acidic peptizing agent, knead in a kneader, then extrude it into strips with an extruder, and dry it at 80 °C for 4 h, 120 °C for 12 h, and then calcine it at 550 °C for 4 h to obtain a molecular sieve / Al2O3 support;

[0077] (7) Impregnate 10 g of the molecular sieve / Al2O3 support with 6.0 g of H2PtCl6 solution (the mass of Pt in the solution is 0.03 g) by the equal-volume impregnation method, dry it at 80 °C for 4 h, 120 °C for 12 h, and then calcine it at 500 °C for 2 h to obtain a Pt-molecular sieve / Al2O3 hydroisomerization catalyst. The mass ratio of Pt to the molecular sieve / Al2O3 support is 0.3%.

[0078] The indicators of API Group III base oil obtained in Example 1 are as follows:

[0079]

[0080] Note: After adding 0.3 wt% of phenolic antioxidant to the base oil, conduct the oxidation stability test according to the SH / T 0193 standard

[0081] The indicators of API Group III base oil obtained in Example 2 are as follows:

[0082]

[0083]

[0084] Note: After adding 0.3 wt% of phenolic antioxidant to the base oil, conduct the oxidation stability test according to the SH / T 0193 standard. The indicators of API Group III base oil obtained in Example 3 are as follows:

[0085]

[0086] Note: The indexes of API Group-III base oil obtained from the comparative example by conducting oxidation stability test according to SH / T 0193 standard after adding 0.3 wt% phenolic antioxidant into the base oil are shown as follows:

[0087]

[0088]

[0089] Note: The indexes of commercially available API Group-III base oil products obtained from conducting oxidation stability test according to SH / T 0193 standard after adding 0.3 wt% phenolic antioxidant into the base oil are shown as follows:

[0090]

[0091] Note: It can be seen from the table that, compared with the comparative example and commercially available S-OIL series samples, for the API Group-III base oils of Examples 1-3 obtained by using the coal-based Fischer-Tropsch wax hydrocracked tail oil, petroleum-based hydrocracked tail oil and coal-based Fischer-Tropsch wax in compound as raw oil components and through hydroisomerization and hydrorefining processes, the viscosity index is higher. Especially when compared with the comparative example under the same kinematic viscosity, the advantage is obvious. The viscosity index represents the degree of change of the viscosity of all fluids with temperature. The higher the viscosity index, the smaller the influence of the fluid viscosity on temperature, that is, the less sensitive the fluid viscosity is to temperature. The lubricating oil base oil with a high viscosity index can fully lubricate the engine within a large temperature range, and at the same time saves the viscosity index improver added in the formula to improve the viscosity index of the lubricating oil.

[0092] The pour point refers to the lowest temperature at which the cooled fluid can flow. Too high pour point indicates that the fluid is difficult to flow and pour at low temperature, which is not conducive to its storage and use at low temperature. Through comparison, it can be seen that the API Group-III base oils of Examples 1-3 have a lower pour point than the comparative example and commercially available S-OIL series samples under the same kinematic viscosity, which is conducive to their use at extremely low temperatures.

[0093] The base oil will become turbid as the temperature decreases, and the temperature at which it becomes turbid is the cloud point. The reason for the appearance of the cloud point is that a part of the paraffins exist in the base oil in the form of flocs and precipitate as the temperature decreases, resulting in the turbidity of the base oil. In the present invention, the Fischer-Tropsch wax is pre-hydrocracked to reduce the molecular weight of the paraffins, and then hydroisomerization and hydrorefining reactions are carried out, thereby reducing the cloud point of the API Group-III base oil. Compared with the comparative example with the same kinematic viscosity, the cloud points of Examples 1-3 of the present invention are significantly lower and are close to the cloud points of commercially available S-OIL series samples.

[0094] In the present invention, the molecular weight of the straight-chain alkanes in coal-based Fischer-Tropsch wax is first degraded by hydrocracking, and then the straight-chain alkanes are converted into highly stable isoparaffin structures through hydroisomerization reaction. Subsequently, the hydrorefining reaction basically removes the unstable components and impurities. The API Group III base oil prepared by this process shows higher oxidation stability and can extend the service life of lubricating oils. The oxidation stability of Examples 1-3 is significantly higher than that of the comparative examples and also has a slight advantage compared with the commercially available S-OIL series samples.

[0095] Finally, the base oils of Examples 1-3 of the present invention also show extremely excellent low-temperature performance. It can be characterized by the low-temperature kinematic viscosity. The low-temperature kinematic viscosity is determined by the cold start simulation test (CCS). CCS simulates the cold start conditions of the piston part of the engine cylinder liner and has a good correlation with the cold start of the engine. The lower the low-temperature kinematic viscosity, the higher the cold start performance of the lubricating oil, which can be used as a viscosity index to predict whether the engine can start smoothly under low-temperature conditions. Examples 1-3 of the present invention have lower low-temperature kinematic viscosities compared with the comparative examples and the commercially available S-OIL series samples under the same kinematic viscosity, especially for the low-temperature kinematic viscosities of the base oils at the three levels of 4 mm 2 / s, 6 mm 2 / s, and 8 mm 2 / s are significantly lower, indicating that such base oils can be used to formulate multi-grade engine oils with lower low-temperature kinematic viscosities.

[0096] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of them. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. Although the specific implementation manners of the present invention have been described above, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative labor on the basis of the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A preparation method of API Group III base oil, characterized in that, The base oil is obtained by successively passing the feedstock oil through a hydroisomerization fixed-bed reactor and a hydrorefining fixed-bed reactor, and then separating it through a separation unit; The feedstock oil includes the following components: Hydrocracked Fischer-Tropsch wax tail oil: 50 - 70 wt% Petroleum-based hydrocracked tail oil: 20 - 40 wt% Fischer-Tropsch wax: 5 - 15 wt%; The rectification cutting temperature range of the Fischer-Tropsch wax hydrocracking tail oil is 260~730 °C; the density of the Fischer-Tropsch wax hydrocracking tail oil at 20 °C is 810~830 kg / m 3 , and the kinematic viscosity at 100 °C is 5.0~7.0 mm 2 / s, and the viscosity index is 180~220; The rectification cutting temperature range of the petroleum-based hydrocracked tail oil is 360~570 °C, and the density of the petroleum-based hydrocracked tail oil at 20 °C is 830~840 kg / m 3 , and the kinematic viscosity at 100 °C is 4.0~6.0 mm 2 / s, and the viscosity index is 130~160; The rectification cutting temperature range of the Fischer-Tropsch wax is 360~580°C; the density of the Fischer-Tropsch wax at 20°C is 810~820 kg / m 3 , and the kinematic viscosity at 100°C is 4.0~6.0 mm 2 / s, and the viscosity index is 150~210; For the hydroisomerization reaction, the feeding rate of the feedstock oil is 250 - 300 g / h, the hydrogen / oil ratio is 1000 - 1500 m 3 / t, the newly introduced hydrogen volume is 300 - 500 L / h, the reaction temperature is 320 - 360 °C, the reaction pressure is 13 - 15 MPa, and the volume space velocity is 1.2 - 2.0 / h; For the hydrofining reaction, the feed rate of the feedstock oil is 250 - 300 g / h, the hydrogen-oil ratio is 1000 - 1500 m 3 / t, the newly introduced hydrogen gas volume is 300 - 500 L / h, the reaction temperature is 220 - 280 °C, the reaction pressure is 13 - 15 MPa, and the volume space velocity is 1.2 - 2.0 / h; The kinematic viscosity of the base oil at 100 °C is 2.0 - 9.0 mm 2 / s, the viscosity index is greater than 125. Among them, for the base oil with a kinematic viscosity above 4.0 mm 2 / s, the viscosity index is greater than or equal to 130, the pour point is less than or equal to -10 °C, the cloud point is less than or equal to 0 °C, the oxidation stability RBOT is greater than 320 min, and the low-temperature fluidity CCS is less than 4200 mPa·s at -30 °C.

2. The preparation method of an API Group III base oil according to claim 1, wherein The initial boiling point temperature range of the distillation cut of the hydrocracked Fischer-Tropsch wax tail oil is 260 - 290°C, and the final boiling point temperature range is 700 - 730°C; the initial boiling point temperature range of the distillation cut of the petroleum-based hydrocracked tail oil is 360 - 380°C, and the final boiling point temperature range is 550 - 570°C; the initial boiling point temperature range of the distillation cut of the Fischer-Tropsch wax is 360 - 380°C, and the final boiling point temperature range is 540 - 550°C.

3. The preparation method of an API Group III base oil according to claim 1, wherein, The density of the feedstock oil at 20 °C is 820 - 840 kg / m 3 ; the kinematic viscosity at 100 °C is 4.0 - 6.0 mm 2 / s; the viscosity index is 150 - 210.

4. The preparation method of an API Group III base oil according to claim 1, characterized in that, The density of the feedstock oil at 20 °C is 830 - 840 kg / m 3 ; the kinematic viscosity at 100 °C is 5.0 - 6.0 mm 2 / s; the viscosity index is 155 - 185.

5. The preparation method of an API Group III base oil according to claim 1, characterized in that, This method uses the above-mentioned feedstock oil to successively pass through a hydroisomerization fixed-bed reactor and a hydrorefining fixed-bed reactor, and then separates it through a separation unit; among them, the separation unit includes: a debutanizer, an atmospheric fractionating column, and a vacuum fractionating column; among them, the hydroisomerization catalyst and the hydrorefining catalyst are respectively loaded in the hydroisomerization fixed-bed reactor and the hydrorefining fixed-bed reactor.

6. The method according to claim 5, characterized in that, The hydroisomerization catalyst includes a carrier and a hydroisomerization component loaded on the carrier; the carrier includes an inorganic porous material and a binder, and the hydroisomerization component is a noble metal element.

7. The method according to claim 6, wherein The inorganic porous material is a molecular sieve, and the binder is alumina and / or silica.

8. The method according to claim 6, wherein The hydroisomerization component is Pt and / or Pd.

9. The method according to claim 6, characterized in that The mass ratio of the hydroisomerization component to the carrier is 0.1 - 0.5%.

10. The method according to claim 6, wherein The mass ratio of the hydroisomerization component to the carrier is 0.3%.

11. The method according to claim 5, wherein The model of the hydroisomerization catalyst is one or more combinations of RDW-1, SLD-800, SLD-821, SLD-861, ICR-400, ICR-404, or ICR-408.

12. The method according to claim 5, wherein The hydrorefining catalyst includes a carrier, an active component, a promoter, and a carrier modifier. The carrier is alumina and / or silica-alumina; the active component is selected from at least one of Group VIII and Group VIB metal elements; the promoter is selected from at least one of Group IA and Group IIA elements; the carrier modifier is selected from at least one of Ce, Zr, Ti, and Si.

13. The method according to claim 5, characterized in that The model of the hydrorefining catalyst is one or more combinations of LN-5, LN-6, RLF-10, or ICR-407.

14. The method according to claim 5, wherein For the hydroisomerization reaction, the feeding rate of the feedstock oil is 290 g / h, the hydrogen-oil ratio is 1200 m 3 / t, the newly introduced hydrogen gas volume is 400 L / h, the reaction temperature is 330 - 355 °C, the reaction pressure is 13 - 15 MPa, and the volume space velocity is 1.3 / h.

15. The method according to claim 5, characterized in that For the hydrofining reaction, the feed rate of the feedstock oil is 290 g / h, the hydrogen-oil ratio is 1200 m 3 / t, the newly introduced hydrogen gas volume is 400 L / h, the reaction temperature is 240 °C, the reaction pressure is 13 - 15 MPa, and the volume space velocity is 1.8 / h.

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