A method for preparing medium-viscosity PAO lubricating oil base oil by using Fischer-Tropsch synthesis middle distillates

Abstract

The present invention provides a method for preparing a medium-viscosity PAO lubricant base oil using a Fischer-Tropsch synthesis intermediate oil product. The method comprises deoxygenating the Fischer-Tropsch synthesis intermediate oil product to obtain an oxygen-containing compound and a deoxygenated Fischer-Tropsch synthesis intermediate oil product. The deoxygenated Fischer-Tropsch synthesis intermediate oil product is then fractionated. The resulting medium-temperature distillate oil and high-temperature distillate oil are subjected to a polymerization reaction, and the product is then subjected to a hydrorefining reaction and fractionation treatment to obtain a medium-viscosity PAO lubricant base oil. The method can effectively utilize the Fischer-Tropsch synthesis intermediate oil product to prepare a polymerization catalyst, thereby improving the economic and ecological benefits of Fischer-Tropsch synthesis and obtaining a medium-viscosity PAO lubricant base oil having a high viscosity index and a low pour point.

Description

Technical Field

[0001] The invention belongs to the field of deep processing of Fischer-Tropsch synthesis products and relates to a method for preparing medium-viscosity PAO lubricant base oil by utilizing Fischer-Tropsch synthesis intermediate oil products. Background Art

[0002] Currently, the α-olefins used in PAO production in my country are primarily obtained through paraffin cracking, while overseas α-olefins are primarily obtained through ethylene oligomerization. This process offers significant advantages over the Chinese paraffin cracking method, but there are currently no ethylene oligomerization production facilities in China, and its production technology has long been monopolized by a few foreign chemical companies. Due to the complex composition, wide distillation range, and low α-olefin content of the raw materials produced by the paraffin cracking method, the quality of the resulting PAO products still lags significantly behind that of overseas products, resulting in my country's long-term reliance on imports for high-quality PAO base oils.

[0003] α-olefins in Fischer-Tropsch intermediates account for nearly 70% of the liquid phase product, with the remainder consisting of normal alkanes and oxygen-containing compounds, primarily alcohols. After separation, suitable components can be used to produce PAO. Therefore, Fischer-Tropsch intermediates can improve the quality and diversity of raw materials for PAO production in my country, addressing the current situation of low-quality and limited raw materials. Using Fischer-Tropsch intermediates to produce PAO base oils can improve the quality of PAO base oil products, fill the gap in my country's production of high-quality PAO lubricant base oils, reduce dependence on imports, ensure energy security, promote the healthy and stable development of the coal-to-liquids industry, and create greater economic and social value.

[0004] CN104152176B discloses a method for producing poly-α-olefin synthetic oil using coal-based feedstocks. This method involves separating the crude α-olefin product produced in an indirect coal liquefaction process into α-olefin components with a distillation range of 80°C-275°C and a carbon number of C5-C12. These components are then polymerized in the presence of a catalyst such as AlCl3 or its alcohol complexes to produce a product with a viscosity index greater than 145. The coal-based α-olefin feedstock in this patent contains isomeric and aromatic components and is not a typical coal indirect liquefaction feedstock. Therefore, the comprehensive application of oxygen-containing compounds in the feedstock is not addressed.

[0005] CN104560189A discloses a method for preparing a high-viscosity lubricant base oil, wherein a Fischer-Tropsch synthetic oil is polymerized in the presence of a Lewis acid catalyst, and the polymer product is hydrotreated to obtain a product. However, because the oxygenates in the Fischer-Tropsch synthetic oil are not separated beforehand, excessive oxygenates can poison the catalyst, making it impossible to efficiently prepare the lubricant base oil. Furthermore, the patent application utilizes a single bulk polymerization process, resulting in a low viscosity index for the PAO.

[0006] In summary, in view of the shortcomings of the existing technology, it is necessary to provide different methods to better utilize the intermediate oil products of Fischer-Tropsch synthesis to prepare medium-viscosity PAO lubricant base oil. Summary of the Invention

[0007] Through research, the inventors have developed a method for preparing a medium-viscosity PAO lubricant base oil from a Fischer-Tropsch intermediate oil. This method allows for the reuse of oxygenated compounds in the feedstock and the flexibility to adjust the composition of the reaction feedstock and catalyst as needed, significantly reducing energy consumption.

[0008] Therefore, the present invention provides a method for preparing a medium-viscosity PAO lubricant base oil using a Fischer-Tropsch synthesis intermediate oil, comprising the following steps:

[0009] (1) deoxygenating the Fischer-Tropsch synthesis intermediate oil to obtain an oxygen-containing compound and a deoxygenated Fischer-Tropsch synthesis intermediate oil;

[0010] (2) fractionating the deoxygenated Fischer-Tropsch synthesis intermediate oil to obtain a low-temperature distillate, a medium-temperature distillate, and a high-temperature distillate;

[0011] (3) mixing an additive with a portion of the optional Fischer-Tropsch oxygenate to obtain a polymerization catalyst containing 0 wt % to 15 wt % of the oxygenate; wherein the additive comprises AlCl 3 , an optional C 5 -C 10 alkane solvent, and an optional oxygenate, and the oxygenate contained in the additive is at least one selected from alcohol, aldehyde, ketone, acid, or ether;

[0012] (4) mixing the medium-temperature distillate oil and the high-temperature distillate oil with the polymerization catalyst to carry out a polymerization reaction, and post-treating the reaction product to obtain a polymerization product to be hydrogenated and a recycled catalyst;

[0013] (5) subjecting the to-be-hydrogenated polymer product to a hydrorefining reaction to obtain a crude polymer oil product;

[0014] (6) fractionating the crude polymerized oil product to obtain a medium-viscosity PAO lubricant base oil.

[0015] The method provided by the present invention for preparing a medium-viscosity PAO lubricant base oil using a Fischer-Tropsch synthesis intermediate oil product can, for example, have the following beneficial effects:

[0016] 1. Improve the quality and diversity of raw materials for PAO production to make up for the current situation of low quality and single variety of domestic raw materials;

[0017] 2. Achieve flexible adjustments based on product orientation and form a multi-dimensional match between products, raw materials and conditions;

[0018] 3. Effectively utilize Fischer-Tropsch synthesis intermediate oils, such as oxygen-containing compounds in Fischer-Tropsch light oil, to prepare polymerization catalysts to obtain medium-viscosity PAO lubricant base oil with a high viscosity index and low pour point, thereby improving the economic and ecological benefits of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are a part of the specification and provide further explanation of the present invention together with the specific embodiments, but are not intended to limit the scope of protection of the present invention.

[0020] Figure 1 The figure is an exemplary process flow chart for preparing medium viscosity PAO lubricant base oil from coal indirect liquefaction products according to the present invention.

[0021] Description of the reference numerals is as follows:

[0022] 1. Fischer-Tropsch intermediate oil; 2. Fischer-Tropsch oxygenates; 3. Deoxygenated Fischer-Tropsch intermediate oil; 4. Extracted oxygenates; 5. Additives; 6. Low-temperature distillate oil; 7. Medium-temperature distillate oil; 8. High-temperature distillate oil; 9. High-viscosity PAO lubricant base oil;

[0023] I, deoxygenation unit; II, polymerization catalyst preparation unit; III, raw material fractionation unit; IV, storage unit; V, tank reactor 1; VI, tank reactor 2; VII, post-processing unit; VIII, hydrofining unit; IX, product distillation unit. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in detail below. The specific embodiments described herein are only used to illustrate and explain the present invention, but are not used to limit the scope of protection of the present invention.

[0025] Based on the composition characteristics of Fischer-Tropsch synthetic oil products (α-olefins account for about 70wt%), if a method can be developed to effectively use Fischer-Tropsch synthetic oil products to prepare medium-viscosity PAO lubricant base oils, it will not only increase the added value of the products, but also help improve the quality of the prepared medium-viscosity PAO lubricant base oils and reduce dependence on high-quality PAO base oils imported from abroad.

[0026] The present invention provides a method for preparing a medium-viscosity PAO lubricant base oil using an intermediate oil product from Fischer-Tropsch synthesis, comprising the following steps:

[0027] (1) deoxygenating the Fischer-Tropsch synthesis intermediate oil to obtain an oxygen-containing compound and a deoxygenated Fischer-Tropsch synthesis intermediate oil;

[0028] (2) fractionating the deoxygenated Fischer-Tropsch synthesis intermediate oil to obtain a low-temperature distillate, a medium-temperature distillate, and a high-temperature distillate;

[0029] (3) mixing an additive with a portion of the optional Fischer-Tropsch oxygenate to obtain a polymerization catalyst containing 0 wt % to 15 wt % of the oxygenate; wherein the additive comprises AlCl 3 , an optional C 5 -C 10 alkane solvent, and an optional oxygenate, and the oxygenate contained in the additive is at least one selected from alcohol, aldehyde, ketone, acid, or ether;

[0030] (4) mixing the medium-temperature distillate oil and the high-temperature distillate oil with the polymerization catalyst to carry out a polymerization reaction, and post-treating the reaction product to obtain a polymerization product to be hydrogenated and a recycled catalyst;

[0031] (5) subjecting the to-be-hydrogenated polymer product to a hydrorefining reaction to obtain a crude polymer oil product;

[0032] (6) fractionating the crude polymerized oil product to obtain a medium-viscosity PAO lubricant base oil.

[0033] Herein, unless otherwise specified, the term "a portion" refers to any value within the range of greater than 0% and less than 100% relative to the total amount of the object it modifies.

[0034] In some embodiments, in step (1), the intermediate oil product of Fischer-Tropsch synthesis is Fischer-Tropsch light oil, and its distillation range is less than 350°C, preferably less than 280°C.

[0035] In some embodiments, in step (1), the Fischer-Tropsch light oil contains 0.1 wt% to 10 wt% of oxygenates, wherein the oxygenates in the Fischer-Tropsch light oil may be one or more of C1-C12 alcohols, aldehydes, ketones, acids, or ethers.

[0036] In step (1), the deoxygenation can be performed according to conventional operation methods known in the art. In some embodiments, in step (1), the deoxygenation can be performed by any one of extraction, physical adsorption, chemical adsorption or hydrogenation.

[0037] In step (2), the fractionation can be carried out according to conventional operating conditions known in the art. In some embodiments, in step (2), the fractionation can be carried out by atmospheric distillation and vacuum distillation. Herein, both the atmospheric distillation and the vacuum distillation can be carried out under conventional operating conditions known in the art. As an example, the top temperature of the atmospheric distillation can be 105°C-125°C, the bottom temperature can be 210°C-260°C, and the number of plates can be 40-60; the vacuum degree of the vacuum distillation can be 10-150 torr (e.g., 30-150 torr), the top temperature can be 160°C-240°C, the bottom temperature can be 200°C-300°C, and the number of plates can be 40-60.

[0038] In some embodiments, in step (2), the low-temperature fraction oil, medium-temperature fraction oil, and high-temperature fraction oil are fraction oils with an end boiling point < 125°C (<C8), fraction oils with an end boiling point between 126°C and 216°C (C8-C12), and fraction oils with an end boiling point between 217°C and 280°C (C13-C14), respectively.

[0039] In some embodiments, in step (3), the polymerization catalyst contains 0 wt% to 5 wt% (such as 0 wt% to 4.5 wt%, 0 wt% to 3.5 wt%) of oxygen-containing compounds.

[0040] The additive described herein is a mixture of AlCl3, an optional oxygen-containing compound, and an optional C5-C10 alkane solvent, and the oxygen-containing compound may include at least one of alcohols, aldehydes, ketones, acids, and ethers. In some embodiments, in step (3), the alcohols include n-propanol, n-butanol, n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, 2,2-dimethylbutanol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, trimethylolpropane, glycerol, pentaerythritol, 2-phenyl-2-propanol; the aldehydes include propionaldehyde, butyraldehyde; the ketones include acetone, butanone; the acid is acetic acid, and the ether is diethyl ether.

[0041] In some embodiments, in step (3), the C5-C10 alkane solvent includes one or more of hexane, cyclohexane, heptane, octane, nonane, and decane.

[0042] In some embodiments, in step (3), the additive contains 0.5 wt% - 100 wt% of AlCl3, 0 wt% - 5 wt% of oxygen-containing compounds, and 0 wt% - 99 wt% of C5-C10 alkane solvents. As a preferred embodiment, the additive may contain 5 wt% - 100 wt% (such as 6.5 wt% - 100 wt%) of AlCl3, 0 wt% - 2.5 wt% of oxygen-containing compounds, and 0 wt% - 95 wt% (such as 0 wt% - 91 wt%) of C5-C10 alkane solvents, wherein the oxygen-containing compound is at least one selected from n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, acetone, and butanone, and the C5-C10 alkane solvent includes one or more of heptane, octane, nonane, and decane.

[0043] In some embodiments, in step (4), the medium-temperature fraction oil and the high-temperature fraction oil are mixed at a mass ratio of 0:1 to 20:1 (such as 5:1 to 15:1).

[0044] In some embodiments, in step (4), the medium-temperature distillate oil and the high-temperature distillate oil are mixed with the polymerization catalyst according to a mass ratio of distillate oil to polymerization catalyst of 100:0.5 to 100:10 (e.g., 100:1 to 100:6, 100:1.5 to 100:5).

[0045] In some embodiments, in step (4), the polymerization reaction is carried out under the following conditions: reaction temperature is 5-80° C., and reaction pressure is 0-1.0 MPa.

[0046] In some embodiments, in step (4), the post-treatment includes: filtering to recover the catalyst, and alkali washing. As an example, Ca(OH)2 powder can be used for the alkali washing. For example, the alkali washing can be performed at 320°C-380°C (e.g., 330°C-360°C).

[0047] In some embodiments, in step (4), the recycled catalyst can be reused in the polymerization reaction.

[0048] In some embodiments, in step (5), a fixed bed is used to carry out the hydrofining reaction. In some specific embodiments, the polymer product to be hydrogenated is heated and then enters from the top of the fixed bed. After hydrogen and the polymer product to be hydrogenated are fully mixed and reacted in the catalyst bed, they are separated by an oil-gas separator, and the resulting polymer oil crude product is discharged from the bottom (for example, the discharge enters the finished product tank through a constant pressure valve). In some preferred embodiments, the hydrofining reaction is carried out under the following conditions: the reaction pressure is 8.0-15.0MPa (for example, 8.0-13.0MPa, 8.0-12.0MPa), the reaction temperature is 300℃-400℃ (for example, 300℃-390℃, 300℃-370℃), and the air velocity is 0.5-2.0h -1 (e.g. 0.8-1.8h -1 ), the catalyst is a Ni-Mo catalyst.

[0049] In this article, the medium viscosity PAO lubricant base oil is a base oil with a viscosity greater than 20 mm at 100 ° C. 2 / s and less than 40mm 2 / s products.

[0050] In some embodiments, in step (6), the main grades of the medium-viscosity PAO lubricant base oil obtained are PAO20, PAO30, PAO40, etc.

[0051] The exemplary technical solutions of the present invention can be described by the following numbered paragraphs:

[0052] 1. A method for preparing a medium-viscosity PAO lubricant base oil using a Fischer-Tropsch intermediate oil product, comprising the following steps:

[0053] (1) deoxygenating the Fischer-Tropsch synthesis intermediate oil to obtain an oxygen-containing compound and a deoxygenated Fischer-Tropsch synthesis intermediate oil;

[0054] (2) fractionating the deoxygenated Fischer-Tropsch synthesis intermediate oil to obtain a low-temperature distillate, a medium-temperature distillate, and a high-temperature distillate;

[0055] (3) mixing an additive with a portion of the optional Fischer-Tropsch oxygenate to obtain a polymerization catalyst containing 0 wt % to 15 wt % of the oxygenate; wherein the additive comprises AlCl 3 , an optional C 5 -C 10 alkane solvent, and an optional oxygenate, and the oxygenate contained in the additive is at least one selected from alcohol, aldehyde, ketone, acid, or ether;

[0056] (4) mixing the medium-temperature distillate oil and the high-temperature distillate oil with the polymerization catalyst to carry out a polymerization reaction, and post-treating the reaction product to obtain a polymerization product to be hydrogenated and a recycled catalyst;

[0057] (5) subjecting the to-be-hydrogenated polymer product to a hydrorefining reaction to obtain a crude polymer oil product;

[0058] (6) fractionating the crude polymerized oil product to obtain a medium-viscosity PAO lubricant base oil.

[0059] 2. The method as described in paragraph 1, wherein, in step (1), the Fischer-Tropsch synthesis intermediate oil product is Fischer-Tropsch light oil, and its distillation range is less than 350°C.

[0060] 3. The method as described in paragraph 1 or 2, wherein, in step (1), the Fischer-Tropsch light oil contains 0.1 wt% to 10 wt% of oxygen-containing compounds.

[0061] 4. The method as described in any one of paragraphs 1 to 3, wherein in step (1), the deoxygenation is carried out by any one of extraction, physical adsorption, chemical adsorption or hydrogenation.

[0062] 5. The method as described in any one of paragraphs 1 to 4, wherein in step (2), the fractionation is performed by atmospheric distillation and reduced pressure distillation.

[0063] 6. The method according to paragraph 5, wherein the top temperature of the atmospheric distillation is 105°C-125°C, the bottom temperature is 210°C-260°C, and the number of plates is 40-60; and the vacuum degree of the reduced pressure distillation is 10-150 torr, the top temperature is 160°C-240°C, the bottom temperature is 200°C-300°C, and the number of plates is 40-60.

[0064] 7. The method of any one of paragraphs 1 to 6, wherein in step (3), the polymerization catalyst contains 0 wt% to 5 wt% of an oxygen-containing compound.

[0065] 8. The method of any one of paragraphs 1 to 7, wherein in step (3), the alcohol comprises n-propanol, n-butanol, n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, 2,2-dimethylbutanol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, trimethylolpropane, glycerol, pentaerythritol, and 2-phenyl-2-propanol; the aldehyde comprises propionaldehyde and butyraldehyde; the ketone comprises acetone and butanone; the acid is acetic acid, and the ether is diethyl ether.

[0066] 9. The method of any one of paragraphs 1 to 8, wherein in step (3), the C5-C10 alkane solvent comprises one or more of hexane, cyclohexane, heptane, octane, nonane, and decane.

[0067] 10. The method of any one of paragraphs 1 to 9, wherein in step (3), the additive comprises 0.5 wt% to 100 wt% of AlCl3, 0 wt% to 5 wt% of an oxygen-containing compound, and 0 wt% to 99 wt% of a C5-C10 alkane solvent.

[0068] 11. The method of paragraph 10, wherein the additive comprises 5 wt%-100 wt% of AlCl3, 0 wt%-2.5 wt% of an oxygen-containing compound, and 0 wt%-95 wt% of a C5-C10 alkane solvent, wherein the oxygen-containing compound is at least one selected from n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, acetone, and butanone, and the C5-C10 alkane solvent comprises one or more of heptane, octane, nonane, and decane.

[0069] 12. The method of any one of paragraphs 1 to 11, wherein in step (4), the medium-temperature distillate oil and the high-temperature distillate oil are mixed in a mass ratio of 0:1 to 20:1.

[0070] 13. The method of any one of paragraphs 1 to 12, wherein in step (4), the medium-temperature distillate oil and the high-temperature distillate oil are mixed with the polymerization catalyst at a mass ratio of distillate oil to polymerization catalyst of 100:0.5 to 100:10.

[0071] 14. The method as described in any one of paragraphs 1 to 13, wherein in step (4), the polymerization reaction is carried out under the following conditions: reaction temperature is 5-80° C., and reaction pressure is 0-1.0 MPa.

[0072] 15. The method as described in any one of paragraphs 1-14, wherein in step (4), the post-treatment includes: filtration and caustic washing.

[0073] 16. The method as described in paragraph 15, wherein Ca(OH)2 powder is used for the caustic washing.

[0074] 17. The method as described in any one of paragraphs 1-16, wherein in step (4), the recycled catalyst is reused in the polymerization reaction.

[0075] 18. The method as described in any one of paragraphs 1-17, wherein in step (5), a fixed bed is used for the hydrorefining reaction.

[0076] 19. The method as described in paragraph 18, wherein after being heated, the product to be hydrorefined enters from the top of the fixed bed. After the hydrogen gas and the product to be hydrorefined are fully mixed and reacted in the catalyst bed, they are separated by an oil-gas separator, and the obtained crude polymerized oil product is discharged from the bottom.

[0077] 20. The method as described in any one of paragraphs 1-19, wherein the hydrorefining reaction is carried out under the following conditions: the reaction pressure is 8.0 - 15.0 MPa, the reaction temperature is 300°C - 400°C, the space velocity is 0.5 - 2.0 h -1 , and the catalyst is a Ni-Mo series catalyst.

[0078] 21. The method as described in any one of paragraphs 1-20, wherein in step (6), the main grades of the obtained medium-viscosity PAO lubricating oil base oil are PAO20, PAO30, and PAO40.

[0079] The present invention will be further described below through specific descriptions, but the scope of the present invention is not limited thereto.

[0080] The oxygenates in the Fischer-Tropsch intermediate oil product are removed by any one of the extraction method, physical adsorption method, chemical adsorption method or hydrogenation method to obtain Fischer-Tropsch oxygenates and deoxygenated Fischer-Tropsch synthesis intermediate oil product. Among them, the deoxygenated Fischer-Tropsch synthesis intermediate oil product is subjected to atmospheric distillation and vacuum distillation (for example, the vacuum degree is 10 - 150 torr) under the conventional conditions in the art to obtain a low-temperature distillate oil with an end boiling point < 125°C (<C8), a medium-temperature distillate oil with an end boiling point between 126 - 216°C (C8 - C12), and a high-temperature distillate oil with an end boiling point between 217 - 280°C (C13 - C14); a part of the optional Fischer-Tropsch oxygenates is mixed with an additive to obtain a polymerization catalyst, wherein the content of AlCl3 in the additive is 5 wt% - 100 wt%, the content of oxygenates is 0 wt% - 5 wt%, and the content of C5 - C10 alkane solvent is 0 wt% - 99.9 wt%.

[0081] The medium-temperature distillate oil and the high-temperature distillate oil are mixed and the polymerization catalyst is added thereto. A polymerization reaction is carried out at a reaction temperature of 5-80° C. and a reaction pressure of 0-1.0 MPa. The reaction product is filtered to recover the catalyst and subjected to post-treatment such as alkali washing to obtain a polymerization product to be hydrogenated and a recycled catalyst. Preferably, the recycled catalyst can be reused in the polymerization reaction.

[0082] The hydrogenated polymer product is placed in a fixed bed hydrogenation reactor at a reaction pressure of 8.0-15.0 MPa, a reaction temperature of 300°C-400°C, and a space velocity of 0.5-2.0 h -1 A hydrorefining reaction is carried out under conditions of a Ni-Mo catalyst to obtain a crude polymer oil product with stable properties. Specifically, during the hydrorefining reaction, the hydrogenated polymer product is heated and then introduced into the top of the fixed bed. The hydrogen and the hydrogenated polymer product are thoroughly mixed and reacted in the catalyst bed before being separated by an oil-gas separator. The crude polymer oil product is discharged from the bottom and enters the finished product tank through a constant pressure valve. The stable crude polymer oil product is fractionated to obtain a medium-viscosity PAO lubricant base oil.

[0083] Example

[0084] Unless otherwise specified, the reagents, materials and devices involved in the following examples are all commercially available in the art; the conventional operations involved in the following examples can be found in patents, patent applications and publications disclosed in the art (for example, He Yongde, ed., "Modern Coal Chemical Technology Handbook", Chemical Industry Press, 2003; Zhang Dexiang, ed., "Basics and Applications of Coal-to-Liquid Technology", Shanghai Science and Technology Press, 2013, but not limited thereto).

[0085] In the present invention, the PAO lubricant base oil performance test method is as follows:

[0086] Determination of kinematic viscosity of petroleum products: GB / T 265

[0087] Calculation method for viscosity index of petroleum products: GB / T 1995

[0088] Determination of pour point of petroleum products: GB / T 3535

[0089] Determination of flash point of lubricating oil: GB / T 3536-2008.

[0090] The properties of the Fischer-Tropsch light oil used in the following examples are shown in the following table:

[0091]

[0092] Example 1

[0093] The Fischer-Tropsch light oil is subjected to an extraction method (the extraction agent is cyclopentane, the volume ratio of the Fischer-Tropsch light oil to the Fischer-Tropsch light oil is 1: 1, and the extraction time is 2h) to remove oxygenated compounds to obtain Fischer-Tropsch oxygenated compounds and deoxygenated Fischer-Tropsch light oil. Then, the deoxygenated Fischer-Tropsch light oil is subjected to atmospheric distillation (tower top temperature 110°C, tower bottom temperature 230°C, tower plate number 50) and vacuum distillation (vacuum degree is 150torr, tower top temperature 220°C, tower bottom temperature 280°C, tower plate number 50) to obtain medium-temperature distillate oil and high-temperature distillate oil. 0.9wt% of the Fischer-Tropsch oxygenated compound is mixed with an additive to obtain a polymerization catalyst. The amount of AlCl3 added in the additive is 6.5wt%, the amount of n-octanol added is 2.5wt%, and the amount of solvent heptane added is 91wt%. The amount of oxygenated compounds in the obtained polymerization catalyst is 3.5wt%.

[0094] The medium-temperature distillate oil and the high-temperature distillate oil are mixed in a mass ratio of 5:1, and then 1.5 wt% of the above-mentioned polymerization catalyst is added relative to the total mass of the medium-temperature distillate oil and the high-temperature distillate oil. The polymerization reaction is carried out at a reaction temperature of 30°C and a reaction pressure of 0.1 MPa. The reaction product is filtered to recover the catalyst and alkali-washed with Ca(OH)2 powder at 335°C until it is neutral, thereby obtaining a polymerization product to be hydrogenated and a recycled catalyst.

[0095] The polymer product to be hydrogenated is placed in a fixed bed hydrogenation reactor at a reaction pressure of 8.0 MPa, a reaction temperature of 300°C, and a space velocity of 1 h -1 , a Ni-Mo catalyst (wherein the Ni content is 2.7wt%, the Mo content is 23.5wt%, and the rest is an aluminum oxide carrier) is used for a hydrorefining reaction to obtain a crude polymer oil product with stable properties. Thereafter, a true boiling point apparatus is used for fractionation under a vacuum degree of 10 torr to obtain a distillate oil with a temperature greater than 330° C., which is the PAO-20 lubricant base oil product. The specific results are shown in Table 1.

[0096] Example 2

[0097] The Fischer-Tropsch light oil is subjected to physical adsorption (the adsorbent is aluminum oxide, and the adsorption time is 5h) to remove oxygenated compounds to obtain Fischer-Tropsch oxygenated compounds and deoxygenated Fischer-Tropsch light oil. Then, the deoxygenated Fischer-Tropsch light oil is subjected to atmospheric distillation (tower top temperature 112°C, tower bottom temperature 230°C, tower plate number 50) and vacuum distillation (vacuum degree is 100torr, tower top temperature 220°C, tower bottom temperature 282°C, tower plate number 50) to obtain medium-temperature distillate oil and high-temperature distillate oil. 0.6wt% of the Fischer-Tropsch oxygenated compounds are mixed with additives to obtain a polymerization catalyst. The amount of AlCl3 added in the additive is 8wt%, the amount of the oxygenated compound n-pentanol added is 2wt%, and the amount of the solvent n-octane added is 90wt%. The amount of oxygenated compounds in the obtained polymerization catalyst is 2.5wt%.

[0098] The medium-temperature distillate oil and the high-temperature distillate oil are mixed in a mass ratio of 10:1, and then 2.5 wt% of the above-mentioned polymerization catalyst is added relative to the total mass of the medium-temperature distillate oil and the high-temperature distillate oil. The polymerization reaction is carried out at a reaction temperature of 20°C and a reaction pressure of 0.2 MPa. The reaction product is filtered to recover the catalyst and alkali-washed with Ca(OH)2 powder at 340°C to neutrality to obtain a polymerization product to be hydrogenated and a recycled catalyst.

[0099] The polymer product to be hydrogenated is placed in a fixed bed hydrogenation reactor at a reaction pressure of 10.0 MPa, a reaction temperature of 350°C, and a space velocity of 1.5 h -1 , a hydrorefining reaction was carried out under the conditions of a Ni-Mo catalyst (wherein the Ni content was 3.8wt%, the Mo content was 25.6wt%, and the rest was an aluminum oxide carrier) to obtain a crude polymer oil product with stable properties. Thereafter, a true boiling point apparatus was used for fractional distillation under a vacuum degree of 2 torr to obtain a distillate oil with a temperature greater than 350°C, which is the PAO-30 lubricant base oil product. The specific results are shown in Table 1.

[0100] Example 3

[0101] The Fischer-Tropsch light oil is subjected to chemical adsorption (the adsorbent is a microporous molecular sieve, and the adsorption time is 3 hours) to remove oxygenated compounds to obtain Fischer-Tropsch oxygenated compounds and deoxygenated Fischer-Tropsch light oil. Subsequently, the deoxygenated Fischer-Tropsch light oil is subjected to atmospheric distillation (top temperature 115°C, bottom temperature 240°C, number of plates 50) and vacuum distillation (vacuum degree 30 torr, top temperature 175°C, bottom temperature 216°C, number of plates 45) to obtain medium-temperature distillate oil and high-temperature distillate oil. 0.7wt% of the Fischer-Tropsch oxygenated compounds are mixed with additives to obtain a polymerization catalyst. The amount of AlCl3 added in the additive is 9.5wt%, the amount of the oxygenated compound butanone added is 1.5wt%, and the amount of the solvent n-decane added is 89wt%. The amount of oxygenated compounds in the obtained polymerization catalyst is 2wt%.

[0102] The medium-temperature distillate oil and the high-temperature distillate oil are mixed in a mass ratio of 15:1, and then 4 wt% of the above-mentioned polymerization catalyst is added relative to the total mass of the medium-temperature distillate oil and the high-temperature distillate oil. The polymerization reaction is carried out at a reaction temperature of 10°C and a reaction pressure of 0.5 MPa. The reaction product is filtered to recover the catalyst and alkali-washed with Ca(OH)2 powder at 360°C to neutrality to obtain a polymerization product to be hydrogenated and a recycled catalyst.

[0103] The polymer product to be hydrogenated is placed in a fixed bed hydrogenation reactor at a reaction pressure of 12.0 MPa, a reaction temperature of 370°C, and a space velocity of 1.8 h -1 , a hydrogenation refining reaction was carried out under the conditions of a Ni-Mo catalyst (wherein the Ni content was 3.7wt%, the Mo content was 27.6wt%, and the rest was an aluminum oxide carrier) to obtain a crude polymer oil product with stable properties. Thereafter, a true boiling point apparatus was used for fractional distillation under a vacuum degree of 2 torr to obtain a distillate oil with a temperature greater than 360°C, which is the PAO-40 lubricant base oil product. The specific results are shown in Table 1.

[0104] Example 4

[0105] The Fischer-Tropsch light oil was extracted using methanol in a 1:1 volume ratio to the Fischer-Tropsch light oil for 1.5 hours to remove oxygenated compounds, yielding Fischer-Tropsch oxygenated compounds and deoxygenated Fischer-Tropsch light oil. The deoxygenated Fischer-Tropsch light oil was then subjected to atmospheric distillation (top temperature 115°C, bottom temperature 238°C, 49 plates) and vacuum distillation (vacuum 100 torr, top temperature 220°C, bottom temperature 282°C, 50 plates) to yield medium-temperature distillate and high-temperature distillate.

[0106] Medium-temperature distillate oil and high-temperature distillate oil are mixed in a mass ratio of 12:1, and then a polymerization catalyst is added in an amount of 5 wt% relative to the total mass of the medium-temperature distillate oil and the high-temperature distillate oil, wherein the polymerization catalyst comprises 100 wt% of AlCl3. A polymerization reaction is carried out at a reaction temperature of 80°C and a reaction pressure of 1 MPa, and the reaction product is filtered to recover the catalyst and alkali-washed with Ca(OH)2 powder at 340°C until it is neutral, thereby obtaining a polymerization product to be hydrogenated and a recycled catalyst.

[0107] The polymer product to be hydrogenated is placed in a fixed bed hydrogenation reactor at a reaction pressure of 8.0 MPa, a reaction temperature of 340°C, and a space velocity of 0.8 h -1, a hydrogenation refining reaction was carried out under the conditions of a Ni-Mo catalyst (wherein the Ni content was 3.0wt%, the Mo content was 26.5wt%, and the rest was an aluminum oxide carrier) to obtain a crude polymer oil product with stable properties. Thereafter, a true boiling point apparatus was used for fractional distillation under a vacuum degree of 10 torr to obtain a distillate oil with a temperature greater than 350°C, which is the PAO-30 lubricant base oil product. The specific results are shown in Table 1.

[0108] Table 1 Analysis results of products in various embodiments

[0109] Example Brand <![CDATA[Viscosity at 100 °C, mm 2 / s]]> Viscosity Index Pour point / ℃ Example 1 PAO-20 20.5 155 <-50 Example 2 PAO-30 29.8 165 <-50 Example 3 PAO-40 41.5 168 <-50 Example 4 PAO-30 30.2 145 <-50

Claims

1. A method for preparing medium-viscosity PAO lubricant base oil from Fischer-Tropsch synthesis intermediate oil products, comprising the following steps: (1) Deoxygenating the Fischer-Tropsch synthesis intermediate oil to obtain Fischer-Tropsch oxygenated compounds and deoxygenated Fischer-Tropsch synthesis intermediate oil, wherein: The Fischer-Tropsch synthesis intermediate oil product is Fischer-Tropsch light oil with a distillation range less than 350 °C, and the Fischer-Tropsch light oil contains 0.1 wt% - 10 wt% of oxygen-containing compounds; (2) Fractionate the deoxygenated Fischer-Tropsch synthesis intermediate oil product to obtain a low-temperature fraction oil with <C8, a medium-temperature fraction oil with C8 - C12, and a high-temperature fraction oil with C13 - C14; (3) Mix an additive with or without a part of the Fischer-Tropsch oxygen-containing compounds to obtain a polymerization catalyst containing 0 wt% to 15 wt% of oxygen-containing compounds; wherein, the additive contains AlCl3; (4) Mix the medium-temperature fraction oil and the high-temperature fraction oil with the polymerization catalyst for a polymerization reaction, and post-treat the reaction product to obtain a hydrogenation polymerization product to be treated and a recycled catalyst, wherein the medium-temperature fraction oil and the high-temperature fraction oil are mixed in a mass ratio of 5:1 to 20:1; (5) Perform a hydrorefining reaction on the hydrogenation polymerization product to be treated to obtain a crude polymerization oil product; (6) Fractionate the crude polymerization oil product to obtain a medium-viscosity PAO lubricant base oil.

2. The method according to claim 1, wherein In step (1), the deoxygenation is carried out by any one of extraction method, physical adsorption method, chemical adsorption method or hydrogenation method.

3. The method according to claim 1 or 2, wherein In step (2), the fractionation is carried out by atmospheric distillation and vacuum distillation.

4. The method according to claim 3, wherein: The top temperature of the atmospheric distillation is 105 °C - 125 °C, the bottom temperature is 210 °C - 260 °C, and the number of trays is 40 - 60; the vacuum degree of the vacuum distillation is 10 - 150 torr, the top temperature is 160 °C - 240 °C, the bottom temperature is 200 °C - 300 °C, and the number of trays is 40 - 60.

5. The method according to claim 1, wherein The additive further contains a C5 - C10 alkane solvent, an oxygen-containing compound, or a C5 - C10 alkane solvent and an oxygen-containing compound, and the oxygen-containing compound contained in the additive is at least one selected from alcohols, aldehydes, ketones, acids or ethers.

6. The method according to claim 5, wherein: In step (3), the polymerization catalyst contains 0 wt% to 5 wt% of the oxygen-containing compound.

7. The method according to claim 5, wherein: In step (3), the alcohols include n-propanol, n-butanol, n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, 2,2-dimethylbutanol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, trimethylolpropane, glycerol, pentaerythritol, 2-phenyl-2-propanol; the aldehydes include propionaldehyde, butyraldehyde; the ketones include acetone, butanone; the acid is acetic acid, and the ether is diethyl ether.

8. The method of claim 5, wherein: In step (3), the C5 - C10 alkane solvent includes one or more of hexane, cyclohexane, heptane, octane, nonane, decane.

9. The method according to any one of claims 5 to 8, wherein In step (3), the additive contains 0.5 wt% - 100 wt% of AlCl3, 0 wt% - 5 wt% of the oxygen-containing compound, 0 wt% - 99 wt% of the C5 - C10 alkane solvent.

10. The method of claim 9, wherein: The additive comprises 5wt%-100wt% of AlCl3, 0wt%-2.5wt% of an oxygen-containing compound, and 0wt%-95wt% of a C5-C10 alkane solvent, wherein the oxygen-containing compound is at least one selected from n-pentanol, isopentanol, n-hexanol, isohexanol, n-heptanol, isoheptanol, n-octanol, acetone, and butanone, and the C5-C10 alkane solvent includes one or more of heptane, octane, nonane, and decane.

11. The method according to claim 1 or 2, wherein: In step (4), the medium-temperature distillate oil and the high-temperature distillate oil are mixed with the polymerization catalyst according to a mass ratio of distillate oil to polymerization catalyst of 100:0.5 to 100:

10.

12. The method according to claim 1 or 2, wherein: In step (4), the polymerization reaction is carried out under the following conditions: reaction temperature is 5-80° C., and reaction pressure is 0-1.0 MPa.

13. The method according to claim 1 or 2, wherein: In step (4), the post-treatment includes: filtration and alkali washing.

14. The method of claim 13, wherein: The alkaline washing is carried out using Ca(OH)2 powder.

15. The method according to claim 1 or 2, wherein: In step (4), the recycled catalyst is reused in the polymerization reaction.

16. The method according to claim 1 or 2, wherein: In step (5), a fixed bed is used to carry out the hydrofining reaction.

17. The method of claim 16, wherein: The polymer product to be hydrogenated is heated and enters from the top of the fixed bed. The hydrogen and the polymer product to be hydrogenated are fully mixed and reacted in the catalyst bed, and then separated by an oil-gas separator. The obtained polymerized crude oil product is discharged from the bottom.

18. The method according to claim 1 or 2, wherein: The hydrofining reaction is carried out under the following conditions: reaction pressure of 8.0-15.0 MPa, reaction temperature of 300°C-400°C, space velocity of 0.5-2.0 h -1 , the catalyst is a Ni-Mo catalyst.

19. The method according to claim 1 or 2, wherein: In step (6), the grades of the medium-viscosity PAO lubricating oil base oil obtained are PAO20, PAO30, and PAO40.

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