Process for producing high viscosity base oil

Abstract

The present disclosure relates to a method for producing high viscosity base oil, comprising: subjecting mineral oil to first atmospheric and vacuum distillation to obtain a first high-boiling fraction; the distillation range of the first high-boiling fraction is between 450-600 DEG C; subjecting Fischer-Tropsch synthesis wax to first hydroprocessing and second atmospheric and vacuum distillation to obtain a second high-boiling fraction; the distillation range of the second high-boiling fraction is between 470-700 DEG C; mixing the first high-boiling fraction and the second high-boiling fraction, subjecting to second hydroprocessing and third atmospheric and vacuum distillation to obtain a third high-boiling fraction; the distillation range of the third high-boiling fraction is between 430-700 DEG C; subjecting the third high-boiling fraction to isodewaxing, hydrofining and fourth atmospheric and vacuum distillation in sequence to obtain a fourth high-boiling fraction; the distillation range of the fourth high-boiling fraction is between 450-700 DEG C; mixing the fourth high-boiling fraction with an organic coagulant aid and subjecting to solvent dewaxing. The method is simple in process and high in product quality.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of lubricating oil base oil production and processing of Fischer-Tropsch synthesis wax, in particular, a method for producing high viscosity base oil. BACKGROUND

[0002] Lubricating oil base oils are generally classified by viscosity, and there is a category of base oils with kinematic viscosity at 100°C temperature not less than 10 mm 2 / s base oil, which is usually referred to as high viscosity base oil, and is usually obtained by solvent deasphalting process from heavy vacuum gas oil, such as four-line cut gas oil, and vacuum residue. The high viscosity base oil produced from deasphalted oil is usually also referred to as bright stock. The traditional bright stock production method is known to those skilled in the art, and the process includes the following steps: (1) a suitable quality mineral oil, usually a medium base crude oil with good viscosity-temperature performance, is subjected to atmospheric and vacuum distillation to obtain vacuum residue; (2) the vacuum residue is subjected to solvent deasphalting to obtain deasphalted oil as a raw material component for producing bright stock; (3) the deasphalted oil is subjected to solvent refining, usually furfural extraction refining to remove non-ideal components such as condensed ring aromatics in the deasphalted oil to obtain furfural refined deasphalted oil, which is referred to as furfural refined oil; (4) the furfural refined oil is subjected to low-temperature dewaxing process with a mixture of methyl ethyl ketone and toluene in a certain proportion as solvent to separate the high condensation point wax component to obtain dewaxed oil; (5) the dewaxed oil is subjected to clay adsorption refining or hydrogenation after refining to obtain bright stock product. The process for producing high viscosity base oil from vacuum gas oil usually includes furfural refining, ketone-toluene dewaxing and clay adsorption refining, etc. The above processes are mainly physical separation processes. In order to meet the requirements of high viscosity base oil on viscosity, viscosity-temperature performance, i.e. viscosity index, and oxidation stability, in addition to the higher requirements for the combination of the process, the raw material also has higher quality requirements, and the product quality and yield are greatly affected by the limitation of crude oil resources. With the trend of global crude oil resources becoming poorer, the source of bright stock is greatly limited. On the other hand, in order to obtain bright stock raw material components from poor residue, the traditional bright stock production method needs to use solvent deasphalting process, which is limited by the quality limitation index such as residual carbon, resulting in a low yield of deasphalted oil, which affects the production efficiency and economy of bright stock.

[0003] In order to improve the adaptability of high viscosity base oil production to raw materials, the developed production method also introduces a chemical conversion process with partial conversion of non-ideal components in the raw material into the above process, usually before or after the furfural refining, a hydroprocessing reaction unit is introduced, through hydrogenation reaction, the polycyclic aromatic hydrocarbons and polycyclic naphthenes which affect the viscosity-temperature performance of the product are converted, and the heteroatom elements in the heterocyclic compounds containing sulfur and nitrogen in the raw material which affect the performance of the product are removed, in order to improve the viscosity-temperature performance and oxidation stability performance of the product, etc. CN102079994B discloses a preparation method of bright stock, which comprises (1) contacting light deasphalted oil with a solvent having selective solubility for macromolecular polycyclic aromatic hydrocarbons to obtain wax-containing refined oil; (2) contacting the wax-containing refined oil with a dewaxing solvent to obtain dewaxed oil and microcrystalline wax paste; (3) contacting a mixture of the dewaxed oil and hydrogen with a hydrotreating catalyst to obtain a first hydrogenated full-range oil; (4) contacting a mixture of the first hydrogenated full-range oil and hydrogen with a hydroisomerization catalyst and a hydrofining catalyst respectively to obtain a second hydrogenated full-range oil; (5) separating a fraction with a boiling point higher than 500°C from the second hydrogenated full-range oil as a bright stock product; obtaining a bright stock product with required kinematic viscosity, high viscosity index, low pour point and no flocculation at room temperature, and by-product microcrystalline wax. However, in this process, in order to control the reaction depth of the hydroprocessing process and avoid excessive loss of viscosity of the target product, resulting in a decrease in the yield of bright stock, it is still necessary to use the furfural refining process to remove polycyclic aromatic hydrocarbons which need to be effectively converted under harsh conditions of hydroprocessing process in advance, resulting in a long production process of bright stock, high energy consumption and low yield.

[0004] To expand the production of bright stock sources, even the mineral oil atmospheric residue is used for high pressure hydrogenation, and then combined with the existing traditional methods or hydrogenation isomerization dewaxing and other methods known in the art to produce bright stock, in order to obtain qualified bright stock. For example, CN102732301B discloses a method for producing bright stock, comprising: (1) under a residue hydrotreating reaction unit and residue hydrotreating reaction conditions, hydrogen, residue feedstock and residue hydrotreating catalyst are contacted and reacted, and a hydrogenated residue with a distillation range of 470°C or more is obtained after separation; (2) under a solvent deasphalting unit and solvent deasphalting conditions, the hydrogenated residue with a distillation range of 470°C or more obtained in step (1) is solvent refined to obtain a solvent refined residue; (3) under a hydrotreating reaction unit and hydrotreating reaction conditions, hydrogen, the solvent refined residue obtained in step (2) and hydrotreating catalyst are contacted and reacted to obtain a hydrotreated solvent refined oil; (4) under a catalytic dewaxing reaction unit and catalytic dewaxing reaction conditions, the hydrotreated solvent refined oil obtained in step (3) is catalytically dewaxed, and bright stock product oil is obtained after separation. It adds a high pressure hydrogenation step to the deasphalting raw material, and further hydrotreating and catalytic dewaxing steps are used after the solvent refining step. This process not only has a complex process, but also requires high sulfur and nitrogen impurities in the isomerization dewaxing step, which leads to harsh hydrotreating conditions, resulting in large viscosity loss of the product, low product yield, and due to incomplete isomerization of macromolecules, the product is prone to generate flocculation, affecting the appearance and performance of the product.

[0005] The hydrogenated product obtained by removing oxygen and olefin double bond in the product obtained by Fischer-Tropsch synthesis reaction using coal, biomass or natural gas as raw material is saturated paraffin. The paraffin with a boiling point higher than 370 DEG C or a carbon number greater than 22 is theoretically a raw material for producing lubricating oil base oil. The raw material basically does not contain aromatic hydrocarbon and naphthenic hydrocarbon. After isomerization dewaxing process, high-quality lubricating oil base oil is obtained. For the high-boiling point component in Fischer-Tropsch synthesis wax, such as paraffin with a distillation range greater than 450 DEG C or a carbon number greater than 30, the component is theoretically a potential raw material for producing high-viscosity base oil or bright stock due to its high boiling point and high viscosity. However, due to the limitation of the development degree of isomerization dewaxing process, after isomerization conversion, a part of long-chain n-alkanes has a low isomerization conversion degree and still has a high condensation point, resulting in high turbidity of the obtained high-viscosity base oil including bright stock, opaque appearance at ambient temperature, so-called "flocculation" in the product, and the like, which affect the quality and use performance of the product. The component with high turbidity in the product has a certain isomerization degree and no longer has the property of wax crystallization at a certain low temperature. The component forms a kind of gelled viscous fluid and is difficult to separate by traditional dewaxing method, which affects the processing and utilization of high-boiling point Fischer-Tropsch synthesis wax and the production of high-viscosity lubricating oil base oil including bright stock. SUMMARY

[0006] The purpose of the present disclosure is to provide a method for producing high-viscosity base oil, which has a simple process and high product quality.

[0007] In order to achieve the above-mentioned purpose, the present disclosure provides a method for producing high-viscosity base oil, which comprises:

[0008] The mineral oil is subjected to first atmospheric and vacuum distillation to obtain a first high-boiling point fraction; the distillation range of the first high-boiling point fraction is between 450 DEG C and 600 DEG C;

[0009] The Fischer-Tropsch synthesis wax is subjected to first hydroprocessing and second atmospheric and vacuum distillation to obtain a second high-boiling point fraction; the distillation range of the second high-boiling point fraction is between 470 DEG C and 700 DEG C;

[0010] The first high-boiling point fraction and the second high-boiling point fraction are mixed, subjected to second hydroprocessing and third atmospheric and vacuum distillation to obtain a third high-boiling point fraction; the distillation range of the third high-boiling point fraction is between 430 DEG C and 700 DEG C;

[0011] The third high-boiling point fraction is subjected to isomerization dewaxing, hydrofining and fourth atmospheric and vacuum distillation in sequence to obtain a fourth high-boiling point fraction; the distillation range of the fourth high-boiling point fraction is between 450 DEG C and 700 DEG C;

[0012] The fourth high-boiling point fraction is mixed with an organic coagulant aid and subjected to solvent dewaxing.

[0013] Optionally, 5wt% of the first high-boiling fraction has a distillation point temperature no less than 450°C, preferably no less than 460°C, further preferably no less than 470°C, based on the total weight of the first high-boiling fraction; 95wt% of the first high-boiling fraction has a distillation point no higher than 600°C, preferably no higher than 580°C, further preferably no higher than 570°C;

[0014] The properties of the first high-boiling fraction include: an open flash point no less than 250°C, preferably no less than 260°C; a carbon residue content no higher than 1.5wt%, preferably no higher than 1wt%; a freezing point no less than 45°C, preferably no less than 50°C; a kinematic viscosity at 100°C no less than 12mm 2 / s, preferably no less than 14mm 2 / s; a n-heptane insoluble content no higher than 200μg / g, preferably no higher than 100μg / g, further preferably no higher than 80μg / g; a viscosity index no less than 45, preferably no less than 55, further preferably no less than 60.

[0015] Optionally, the conditions of the first hydroprocessing include: a hydrogen partial pressure of 5-14MPa, preferably 6-12MPa, further preferably 6-10MPa; a reaction temperature of 260-380°C, preferably 280-360°C, further preferably 300-350°C; a liquid hourly space velocity of 0.4-2.0h -1 , preferably 0.6-1.5h -1 , further preferably 0.8-1.2h -1 ; a hydrogen to oil volume ratio of (300-1200):1, preferably (500-1000):1, further preferably (600-800):1.

[0016] Optionally, the properties of the second high-boiling fraction include: a carbon number no less than 30, preferably no less than 33, further preferably no less than 36; a kinematic viscosity at 100°C no less than 28mm 2 / s, preferably no less than 31mm 2 / s, further preferably no less than 33mm 2 / s; a total metal content no greater than 20μg / g, with an iron ion content no greater than 10μg / g, preferably a total metal content no greater than 15μg / g, with an iron ion content no greater than 6μg / g, further preferably a total metal content no greater than 10μg / g, with an iron ion content no greater than 3μg / g; a n-heptane insoluble content no greater than 200μg / g, preferably no greater than 150μg / g, further preferably no greater than 100μg / g.

[0017] Optionally, the content of the second high-boiling fraction is 10 to 70 parts by weight, based on 100 parts by weight of the mixture of the first high-boiling fraction and the second high-boiling fraction.

[0018] Optionally, the conditions of the second hydroprocessing include: hydrogen partial pressure is 8 to 18 MPa, preferably 12 to 18 MPa, further preferably 14 to 18 MPa; reaction temperature is 330 to 420°C, preferably 350 to 400°C, further preferably 350 to 380°C; liquid hourly space velocity is 0.2 to 1.4 h -1 , preferably 0.3 to 1.2 h -1 , further preferably 0.4 to 0.8 h -1 ; hydrogen to oil volume ratio is (300 to 1200) : 1, preferably (500 to 1000) : 1, further preferably (600 to 900) : 1.

[0019] Optionally, the properties of the third high-boiling fraction include: sulfur content is not more than 30 μg / g, nitrogen content is not more than 10 μg / g, preferably sulfur content is not more than 20 μg / g, nitrogen content is not more than 5 μg / g, further preferably sulfur content is not more than 15 μg / g, nitrogen content is not more than 3 μg / g.

[0020] Optionally, the conditions of the isodewaxing include: reaction temperature is 310 to 380°C, preferably 320 to 380°C, further preferably 350 to 375°C; volume liquid hourly space velocity is 0.5 to 2.0 h -1 , preferably 0.6 to 1.4 h -1 , further preferably 0.8 to 1.2 h -1 ; reaction pressure is 4 to 16 MPa, preferably 6 to 14 MPa, further preferably 8 to 14 MPa; hydrogen to oil volume ratio is (500 to 1200) : 1, preferably (600 to 1000) : 1, further preferably (800 to 1000) : 1.

[0021] Optionally, the conditions of the hydrofining include: reaction temperature is 200 to 280°C, preferably 210 to 260°C, further preferably 220 to 260°C; volume liquid hourly space velocity is 0.3 to 2 h -1 , preferably 0.4 to 1.6 h -1 , further preferably 0.5 to 1 h -1 ; reaction pressure is 2 to 16 MPa, preferably 4 to 14 MPa, further preferably 6 to 12 MPa; hydrogen to oil volume ratio is (500 to 1200) : 1, preferably (600 to 1200) : 1, further preferably (800 to 1200) : 1.

[0022] Optionally, the distillation point temperature of 5% by weight of the fourth high-boiling point fraction is not lower than 450℃, preferably not lower than 500℃, based on the total weight of the fourth high-boiling point fraction;

[0023] The properties of the fourth high-boiling point fraction include: the kinematic viscosity at 100℃ is not lower than 24mm 2 / s, preferably not lower than 28mm 2 / s; the open flash point is not lower than 280℃, preferably not lower than 290℃; the pour point is not higher than -18℃, preferably not higher than -20℃.

[0024] Optionally, the organic coagulant is a wax derived from mineral oil and / or Fischer-Tropsch synthesis oil, preferably paraffin wax and / or microcrystalline wax and mixtures thereof in any proportion;

[0025] The content of the organic coagulant is 10-20 parts by weight, based on 100 parts by weight of the mixture of the fourth high-boiling point fraction and the organic coagulant.

[0026] Optionally, the solvent dewaxing conditions include: the solvent is a mixture of methyl ethyl ketone-toluene; the filtration temperature is -25℃ to 20℃, preferably -20℃ to 15℃.

[0027] By the above technical solution, the present disclosure uses mineral oil and Fischer-Tropsch synthesis wax as raw materials to produce high-viscosity base oil, which has the following technical features:

[0028] (1) Compared with the traditional process method, the method provided by the present disclosure does not contain the propane deasphalting process, and no longer contains the solvent refining process, greatly simplifying the process;

[0029] (2) The raw material for producing high-viscosity base oil by the method provided by the present disclosure is no longer limited to propane deasphalting oil from vacuum residue, but is directly obtained from the vacuum tower of the distillation device;

[0030] (3) The high-viscosity base oil produced by the method of the present disclosure has a higher content of isoparaffin than the traditional method, has better viscosity-temperature performance, i.e., has a higher viscosity index, which is higher than the index specified in the product standard by more than 10 units;

[0031] (4) Eliminate the shortcomings of existing high-boiling point Fischer-Tropsch wax fraction, such as opaque appearance, high turbidity, and easy to produce flocculent substances, when producing high-viscosity base oil.

[0032] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0033] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not intended to limit the present disclosure.

[0034] The present disclosure provides a method for producing high viscosity base oil, comprising:

[0035] subjecting mineral oil to first atmospheric and vacuum distillation to obtain a first high boiling fraction; the distillation range of the first high boiling fraction is between 450-600℃;

[0036] subjecting Fischer-Tropsch synthesis wax to first hydroprocessing and second atmospheric and vacuum distillation to obtain a second high boiling fraction; the distillation range of the second high boiling fraction is between 470-700℃;

[0037] mixing the first high boiling fraction and the second high boiling fraction, subjecting to second hydroprocessing and third atmospheric and vacuum distillation to obtain a third high boiling fraction; the distillation range of the third high boiling fraction is between 430-700℃;

[0038] subjecting the third high boiling fraction to isodewaxing, hydrofining and fourth atmospheric and vacuum distillation in sequence to obtain a fourth high boiling fraction; the distillation range of the fourth high boiling fraction is between 450-700℃;

[0039] mixing the fourth high boiling fraction with an organic coagulant aid and subjecting to solvent dewaxing.

[0040] The conventional process for producing high viscosity base oil (including bright stock) from mineral oil is to use vacuum residue of mineral oil as raw material, to obtain deasphalted oil from the vacuum residue by propane deasphalting method as raw material, and then to go through a series of processes such as solvent refining (e.g. furfural refining), solvent dewaxing (e.g. ketone benzene dewaxing), and supplemental refining (e.g. clay adsorption refining). This process mainly combines a series of physical separation processes, respectively using the selective solubility of different solvents for different components in petroleum to achieve the refining treatment of the raw material; using the selective solubility of solvents for non-paraffin hydrocarbons at low temperature to achieve the separation of high freezing point components, so as to improve the low temperature fluidity of the product; and finally using adsorption method to improve the color and stability of the product.

[0041] This conventional method for producing bright stock is based on the process of removing non-ideal components from the raw material, so the quality of the raw material has an important influence on the yield and quality of the final bright stock. With the development of global crude oil deterioration trend, the production of bright stock is facing the problem of raw material shortage, which cannot meet the market demand.

[0042] With the development of Fischer-Tropsch synthesis technology, synthesis gas can be obtained from coal, natural gas, biomass and the like, so as to further obtain long-chain normal alkanes, i.e. Fischer-Tropsch synthesis wax or Fischer-Tropsch wax, through the Fischer-Tropsch synthesis process. The Fischer-Tropsch wax with a high carbon number has the characteristics of high viscosity and high viscosity index, and is a potential raw material for producing bright stock. However, since the Fischer-Tropsch synthesis product is basically composed of normal alkanes, it has a very high freezing point, and the oil component with a low freezing point cannot be obtained through the traditional ketone-benzene dewaxing method. Therefore, the traditional method is not suitable for the production of base oil, especially high-viscosity base oil or bright stock, using Fischer-Tropsch wax as the raw material.

[0043] The application of the development of normal alkane isomerization technology makes it possible to produce high-quality lubricating base oil using Fischer-Tropsch wax. However, due to the current development level of isomerization technology, the isomerization degree of part of the long-chain normal alkane molecules cannot meet the requirement of reaching a low pour point when the technology is used to produce base oil from Fischer-Tropsch wax with a high carbon number. The high-viscosity product obtained has a high cloud point, is not transparent at ambient temperature, and has flocculent substances precipitated, which affects the appearance and use performance of the product.

[0044] When the traditional ketone-benzene dewaxing process is directly combined with the isomerization dewaxing process to produce high-viscosity base oil or bright stock from high-boiling Fischer-Tropsch wax, the quality of the wax cake cannot be good in the filtration unit of the ketone-benzene dewaxing process due to the change in the properties of the high-freezing-point wax component after isomerization, which causes difficulty in filtration and cannot produce normally.

[0045] In view of the problems of the existing technical method, such as the limitation of raw material sources, the complexity of the process, and the unstable operation of the production process, the present disclosure provides a method for producing high-viscosity base oil (including bright stock) using mineral oil and Fischer-Tropsch synthesis wax as raw materials. The method eliminates the propane deasphalting process and the furfural refining process in the traditional production method, simplifies the process of obtaining raw materials and the limitation on the quality of raw materials, widens the sources of raw materials, and provides a method for producing high-quality high-viscosity base oil (including bright stock) with high viscosity, low cloud point and high viscosity index in a simplified process.

[0046] In the present disclosure, the mineral oil is usually a type of intermediate-base crude oil or a mixed crude oil with intermediate-base characteristics. The properties of intermediate-base crude oil are known to those skilled in the art, and will not be described herein.

[0047] The first high-boiling point fraction can be obtained from the side line of the vacuum tower by first atmospheric-vacuum distillation of mineral oil, which is a high-boiling point (≥450℃) vacuum wax oil fraction. The distillation range of the first high-boiling point fraction is between 450-600℃, preferably between 450-580℃, and further preferably between 460-570℃. In a preferred embodiment of the present disclosure, 5% by weight of the first high-boiling point fraction has a distillation point temperature of no less than 450℃, preferably no less than 460℃, and further preferably no less than 470℃, based on the total weight of the first high-boiling point fraction; 95% by weight of the first high-boiling point fraction has a distillation point of no more than 600℃, preferably no more than 580℃, and further preferably no more than 570℃. The physicochemical properties of the first high-boiling point fraction can include: an open flash point of no less than 250℃, preferably no less than 260℃; a carbon residue content of no more than 1.5% by weight, preferably no more than 1% by weight; a freezing point of no less than 45℃, preferably no less than 50℃; a 100℃ kinematic viscosity of no less than 12.0mm 2 / s, preferably no less than 14.0mm 2 / s; a n-heptane insoluble content of no more than 200μg / g, preferably no more than 100μg / g, and further preferably no more than 80μg / g; and a viscosity index of no less than 45, preferably no less than 55, and further preferably no less than 60.

[0048] In the present disclosure, the carbon number of the Fischer-Tropsch synthesis wax can vary within a large range, for example, can be C14-C100, and the distillation temperature range can be 250-700℃. The properties of the Fischer-Tropsch synthesis wax have no special requirements except for mechanical impurities and metal content, wherein the mechanical impurity content is no more than 100mg / kg, the particle size is no more than 25μm, and the total metal content is no more than 10mg / kg.

[0049] The Fischer-Tropsch synthesis wax is subjected to first hydroprocessing, and the obtained Fischer-Tropsch wax full fraction is subjected to second atmospheric-vacuum distillation cutting, and the second high-boiling point fraction can be obtained from the bottom of the vacuum tower, which is a high-carbon number Fischer-Tropsch vacuum tower bottom fraction. The conditions of the first hydroprocessing can include: a hydrogen partial pressure of 5-14MPa, preferably 6-12MPa, and further preferably 6-10MPa; a reaction temperature of 260-380℃, preferably 280-360℃, and further preferably 300-350℃; a liquid hourly space velocity of 0.4-2.0h -1 , preferably 0.6-1.5h -1 , and further preferably 0.8-1.2h -1; the hydrogen to oil volume ratio is (300-1200): 1, preferably (500-1000): 1, and further preferably (600-800): 1. The catalyst used can be a refined type hydrogenation catalyst with Ni, W, Mo and other metal active components supported on alumina.

[0050] The distillation range of the second high-boiling fraction is between 470-700°C, preferably between 500-700°C, and further preferably between 510-700°C. The properties of the second high-boiling fraction can include: carbon atom number not less than 30, preferably not less than 33, and further preferably not less than 36; 100°C kinematic viscosity not less than 28 mm 2 / s, preferably not less than 31 mm 2 / s, and further preferably not less than 33 mm 2 / s; total metal content not more than 20 μg / g, in which the iron ion content is not more than 10 μg / g, preferably total metal content not more than 15 μg / g, in which the iron ion content is not more than 6 μg / g, and further preferably total metal content not more than 10 μg / g, in which the iron ion content is not more than 3 μg / g; n-heptane insoluble content not more than 200 μg / g, preferably not more than 150 μg / g, and further preferably not more than 100 μg / g.

[0051] The first high-boiling fraction and the second high-boiling fraction are mixed to obtain a mixed fraction. The mixing method of the first high-boiling fraction and the second high-boiling fraction can adopt mechanical mixing methods, including stirring, pump circulation, mixing with static mixers, etc. The content of the second high-boiling fraction can be 10-70 parts by weight, for example 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, etc., based on 100 parts by weight of the mixture of the first high-boiling fraction and the second high-boiling fraction, and is preferably 30-60 parts by weight.

[0052] The mixture of the first high-boiling fraction and the second high-boiling fraction is contacted with a hydrogenation catalyst in the presence of hydrogen to perform a second hydroprocessing. The conditions of the second hydroprocessing can include: hydrogen partial pressure in the reaction zone is 8-18 MPa, preferably 12-18 MPa, and further preferably 14-18 MPa; reaction temperature is 330-420°C, preferably 350-400°C, and further preferably 350-380°C; liquid hourly space velocity is 0.2-1.4 h -1 , preferably 0.3-1.2 h -1 , and further preferably 0.4-0.8 h -1; the hydrogen to oil volume ratio is (300-1200): 1, preferably (500-1000): 1, and further preferably (600-900): 1. The catalyst used in the second hydroprocessing reaction system can be a catalyst containing Ni or / and W and Mo metals. The obtained hydrogenated product is subjected to a third atmospheric and vacuum distillation to obtain a third high-boiling fraction as a raw material for further isodewaxing. The third high-boiling fraction has a distillation range of 430-700°C, preferably 450-700°C, and further preferably 470-700°C. The properties of the third high-boiling fraction can include: a sulfur content of not more than 30 μg / g, a nitrogen content of not more than 10 μg / g, preferably a sulfur content of not more than 20 μg / g, a nitrogen content of not more than 5 μg / g, and further preferably a sulfur content of not more than 15 μg / g, a nitrogen content of not more than 3 μg / g.

[0053] The third high-boiling fraction is sequentially contacted with an isodewaxing catalyst and a hydrofining catalyst in the presence of hydrogen, and the product is subjected to a fourth atmospheric and vacuum distillation to remove light components and obtain a fourth high-boiling fraction at the bottom of the vacuum tower. The isodewaxing conditions can include: a reaction temperature of 310-380°C, preferably 320-380°C, and further preferably 350-375°C; a volume liquid hourly space velocity of 0.5-2.0 h -1 , preferably 0.6-1.4 h -1 , and further preferably 0.8-1.2 h -1 ; a reaction pressure of 4-16 MPa, preferably 6-14 MPa, and further preferably 8-14 MPa; and a hydrogen to oil volume ratio of (500-1200): 1, preferably (600-1000): 1, and further preferably (800-1000): 1. The hydrofining conditions can include: a reaction temperature of 200-280°C, preferably 210-260°C, and further preferably 220-260°C; a volume liquid hourly space velocity of 0.3-2 h -1 , preferably 0.4-1.6 h -1 , and further preferably 0.5-1 h -1; the reaction pressure is 2-16 MPa, preferably 4-14 MPa, and further preferably 6-12 MPa; and the hydrogen / oil volume ratio is (500-1200): 1, preferably (600-1200): 1, and further preferably (800-1200): 1. The catalysts used in the isodewaxing and hydrofinishing reactions can be those known in the art, for example, the isodewaxing catalyst can be a noble metal reduced catalyst containing Pt, and the hydrofinishing catalyst can be a double noble metal reduced catalyst containing Pt / Pd. The fourth high-boiling fraction has a distillation range of 430-700°C, preferably 450-700°C, and further preferably 470-700°C. Further, the distillation point of 5% by weight of the fourth high-boiling fraction is not less than 450°C, and preferably not less than 500°C, based on the total weight of the fourth high-boiling fraction. The properties of the fourth high-boiling fraction can include: a kinematic viscosity at 100°C of not less than 24 mm 2 / s, preferably not less than 28 mm 2 / s; an open flash point of not less than 280°C, preferably not less than 290°C; a pour point of not higher than -18°C, preferably not higher than -20°C; and a cloud point in the range of 5-40°C, preferably 10-35°C, and further preferably 20-35°C.

[0054] The fourth high-boiling fraction is mixed with an organic coagulant to perform solvent dewaxing, and the high-coagulation-point components are removed, so that a high-viscosity base oil or bright stock having qualified kinematic viscosity, pour point and cloud point, and being clear and transparent without "flocculation" at ambient temperature can be obtained.

[0055] The organic coagulant is a wax that can be derived from mineral oil and / or Fischer-Tropsch synthetic oil, and is preferably paraffin wax and / or microcrystalline wax and a mixture thereof in any ratio, and functions to assist in the formation of a wax cake during dewaxing at low temperature filtration, so as to facilitate the normal operation of the filtration separation process, and can also form a co-crystal with the components in the high-boiling fraction that are prone to form flocculation, so as to achieve the separation purpose. The melting point of the paraffin wax can be not less than 54°C, and preferably not less than 56°C; and the melting point of the microcrystalline wax can be not less than 65°C, and preferably not less than 70°C. The fourth high-boiling fraction and the organic coagulant can be mixed in a mechanical mixing manner, and the content of the organic coagulant can be 10-20 parts by weight, such as 10 parts by weight, 15 parts by weight, 20 parts by weight, and the like, based on 100 parts by weight of the mixture of the fourth high-boiling fraction and the organic coagulant, and is preferably 12-18 parts by weight.

[0056] The solvent dewaxing is well known to those skilled in the art, and the solvent used is commonly used by those skilled in the art, for example, it can be a ketone benzene dewaxing solvent, preferably one or more of benzene, acetone, toluene and butanone; preferably, the solvent used is a ketone benzene complex solvent, for example, a butanone-toluene mixed solvent, the ketone benzene dewaxing solvent contains benzene compounds and ketone compounds, and the weight ratio of the content of the benzene compounds and the ketone compounds can be 1:(1-3), preferably 1:(1-2). In a preferred specific embodiment, the ketone benzene dewaxing solvent is a methyl ethyl ketone-toluene mixed solvent, and the weight ratio of methyl ethyl ketone and toluene can be 1:(1-2), preferably 1:(1-1.5). The weight ratio of the mixture of the fourth high-boiling fraction and the organic coagulant to the amount of solvent used can vary within a wide range, for example, it can be 1:(1-1.5), preferably 1:(1-1.2). The conditions of the solvent dewaxing can also include that the filtration temperature is -25℃ to 20℃, preferably -20℃ to 15℃. After the solvent dewaxing, the solvent can be recovered, and the recovery method is not specifically limited, for example, the solvent can be recovered by evaporation.

[0057] After the solvent dewaxing and evaporation recovery of the filtrate, a high-viscosity base oil or bright stock with qualified kinematic viscosity, pour point and cloud point, clear and transparent without "flocculation" at ambient temperature is obtained, and the 100℃ kinematic viscosity range of the high-viscosity base oil or bright stock can be 17-34mm 2 / s, the viscosity index can be not less than 100, the cloud point can be not higher than -5℃, and the pour point can be not higher than -15℃.

[0058] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited in any way by the examples.

[0059] In the examples, the source of mineral oil is a Middle East intermediate base crude oil, and the source of Fischer-Tropsch synthetic wax is a commercially available Fischer-Tropsch synthetic oil (carbon number range C14-C90, distillation temperature range 250-700°C, mechanical impurity content 80 mg / kg, mechanical impurity particle size not greater than 25 μm after filtration using a 25 μm filter element; total metal content 8 mg / kg). The pour point is determined according to the Petroleum Products Pour Point Test Method in GB / T3535-2006 standard; the cloud point is determined according to the Petroleum Products Cloud Point Test Method in GB / T6986-2014 standard; the 100°C kinematic viscosity is determined according to the Petroleum Products Kinematic Viscosity Test Method and Kinematic Viscosity Calculation Method in GB / T265-1988 standard; the viscosity index is determined according to the Petroleum Products Viscosity Index Calculation Method in GB / T1995-1998 standard; the open flash point is determined according to the Petroleum Products Flash Point and Ignition Point Test Method (Open Cup Method) in GB / T276-1988 standard; the freezing point is determined according to the Petroleum Products Freezing Point Test Method in GB / T510-2018 standard; the melting point is determined according to the Paraffin Wax Melting Point Test Method in GB / T2539-1981 standard; the carbon residue content is determined according to the Petroleum Products Carbon Residue Test Method in GB / T17144-2021 standard; the n-heptane insoluble content is determined by the Membrane Filtration Method; the total metal content and iron ion content are determined by the Inductively Coupled Plasma Atomic Emission Spectrometry Method in GB / T17476-1998 standard; the sulfur content is determined by the Sulfur Content Test Method in Petroleum and Petroleum Products in GB / T17040-2019 standard; and the nitrogen content is determined by the Nitrogen Content Test Method in Petroleum and Petroleum Products in SH / T0704-2001 standard.

[0060] Example 1

[0061] The intermediate base crude oil is subjected to first atmospheric and vacuum distillation to obtain a first high-boiling fraction with 5% by weight distillation point > 460°C and 95% by weight distillation point < 580°C, and the properties thereof are shown in Table 1.

[0062] The Fischer-Tropsch synthetic wax is subjected to first hydroprocessing and second atmospheric and vacuum distillation to obtain a second high-boiling fraction with 5% by weight distillation point not less than 470°C and minimum carbon number not less than 33 carbon atoms, and the properties thereof are shown in Table 2. The catalyst used for the first hydroprocessing is a hydrofining catalyst of Ni, W and Mo (purchased from Sinopec Catalyst Company, trade name RJW-2), and the reaction conditions are: hydrogen partial pressure 10 MPa, reaction temperature 330°C, liquid hourly space velocity 0.8 h -1 , hydrogen to oil volume ratio 500:1.

[0063] The first high-boiling fraction and the second high-boiling fraction were mixed by mechanical stirring at a mixing ratio of 70:30 by weight, and the mixing temperature was 150°C to obtain a mixture. The mixture was subjected to a second hydroprocessing, and was subjected to a third atmospheric and vacuum distillation to obtain a third high-boiling fraction, the properties of which are shown in Table 3. The second hydroprocessing was performed using a catalyst containing Ni, W and Mo (purchased from Sinopec Catalyst Co., Ltd., product number RL-2), and the reaction conditions were: hydrogen partial pressure 15.0 MPa, reaction temperature 365°C, liquid hourly space velocity 0.4 h -1 , hydrogen to oil volume ratio 1000:1.

[0064] The third high-boiling fraction was sequentially contacted with an isodewaxing catalyst and a hydrofinishing catalyst in the presence of hydrogen, wherein the isodewaxing catalyst was a noble metal reduced catalyst containing Pt (purchased from Sinopec Catalyst Co., Ltd., product number RIW-2), and the hydrofinishing catalyst was a double noble metal reduced catalyst containing Pt / Pd (purchased from Sinopec Catalyst Co., Ltd., product number RLF-20). The isodewaxing conditions were: pressure 12.0 MPa, temperature 352°C, volume liquid hourly space velocity 0.8 h -1 , hydrogen to oil volume ratio 1000:1. The hydrofinishing conditions were: pressure 10.0 MPa, temperature 230°C, volume liquid hourly space velocity 1.0 h -1 , hydrogen to oil volume ratio 1000:1. The resulting oil was subjected to a fourth atmospheric and vacuum distillation to obtain a fourth high-boiling fraction, the properties of which are shown in Table 4.

[0065] The fourth high-boiling fraction was mixed with paraffin wax to obtain a mixture, wherein the mixing ratio of the fourth high-boiling fraction to paraffin wax was 85:15 by weight, and the paraffin wax was a full refining wax with a Saybolt color of +30 and a melting point of 56°C. The resulting mixture was subjected to solvent dewaxing using a mixed solvent of methyl ethyl ketone-toluene, the weight ratio of methyl ethyl ketone to toluene being 1:1.5, and the weight ratio of the mixture to the solvent used being 1:1.2, and a filtration temperature of -20°C to obtain a high viscosity base oil, the properties of which are shown in Table 5.

[0066] Example 2

[0067] A high viscosity base oil was produced according to the method of Example 1, except that the mixing ratio of the first high-boiling fraction to the second high-boiling fraction was 80:20 by weight, and the properties of the product are shown in Table 5.

[0068] Example 3

[0069] A high viscosity base oil was produced according to the method of Example 1, except that the mixing ratio of the first high-boiling fraction to the second high-boiling fraction was 30:70 by weight, and the properties of the product are shown in Table 5.

[0070] Example 4

[0071] The high viscosity base oil was produced according to the method of Example 1, except that the mixing ratio of the fourth high-boiling fraction to paraffin wax was 90:10 by weight, and the product properties are shown in Table 5.

[0072] Example 5

[0073] The high viscosity base oil was produced according to the method of Example 1, except that the same weight of microcrystalline wax was used to replace paraffin wax, and the melting point of the microcrystalline wax was 68°C, and the product properties are shown in Table 5.

[0074] Comparative Example 1

[0075] The bright stock was prepared using petroleum-based vacuum residue as raw material and a traditional propane deasphalting-furfural refining-ketone-toluene dewaxing- clay method, including the following steps: (1) mixing the vacuum residue with propane solvent, the solvent mass ratio was 2.5:1, the operating pressure was 3.6 MPa, the top temperature of the settling column was 65°C, and the bottom temperature of the settling column was 42°C, and the light deasphalted oil was obtained after solvent recovery of the overhead product; (2) mixing the light deasphalted oil with furfural solvent, the solvent mass ratio was 3.5:1, the overhead temperature of the extraction column was 110°C, and the bottom temperature of the extraction column was 65°C, and the furfural refined oil was obtained after solvent recovery of the overhead product; (3) sequentially diluting the furfural refined oil with a mixture of butanone and toluene at different temperatures of -20°C to 75°C, and uniformly mixing and gradually cooling to crystallize, and then filtering and separating at -20°C, wherein the mass ratio of butanone to toluene in the mixed solvent was 50:50, and the total solvent mass ratio was 4.8:1, and the obtained filtrate was subjected to solvent recovery to obtain the dewaxed oil; (4) mixing the dewaxed oil with activated clay at 118°C, maintaining the temperature and stirring for 30 minutes, and then filtering, wherein the amount of clay was 5.2% by weight of the dewaxed oil, and the filtrate was the prepared bright stock, and the product properties are shown in Table 5.

[0076] Comparative Example 2

[0077] The high viscosity base oil was produced according to the method of Example 1, except that no paraffin wax was added in the solvent dewaxing process, and the product properties are shown in Table 5.

[0078] Table 1 Properties of the first high-boiling fraction

[0079]

[0080]

[0081] Table 2 Properties of the second high-boiling fraction

[0082] Density (20°C) / (kg / m3) 3 )]> 899.2 100 °C kinematic viscosity / (mm 2 / s) 32.64 Melting point / °C 117 Carbon number distribution range C35 to C98 n-Heptane insolubles / (μg / g) 73 Total metal content / (μg / g) 5.2 Iron ion content / (μg / g) 2.1 Distillation range / °C 5％ 473 95％ 689

[0083] Table 3 Properties of the third high-boiling fraction

[0084] Density (20°C) / (kg / m3) 3 ​ 917.4 100 °C kinematic viscosity / (mm 2 / s) 19.57 Solidification point / °C >50 Sulfur content / (μg / g) 8.3 Nitrogen content / (μg / g) 2.6 Distillation range / °C 5％ 463 95％ 672

[0085] Table 4 Fourth high-boiling fraction properties

[0086]

[0087]

[0088] Table 5 High viscosity base oil product properties

[0089]

[0090] From the above results of Examples 1-5, it can be seen that the high viscosity base oil with qualified kinematic viscosity, viscosity index, pour point and cloud point, clear and transparent without "floc" at ambient temperature can be obtained by using the method of the present disclosure. The process of Comparative Example 1 is complex, the viscosity index of the obtained product is low, and the pour point is high; in Comparative Example 2, no organic coagulant is added in the solvent dewaxing process, the obtained product has high cloud point and turbid appearance.

[0091] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0092] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present disclosure will not further describe various possible combination manners.

[0093] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as it does not deviate from the idea of the present disclosure, and it should be considered as disclosed by the present disclosure.

Claims

1. A method of producing a high viscosity base oil, characterized by, The method comprises: mineral oil is subjected to first atmospheric and vacuum distillation to obtain a first high-boiling fraction; the distillation range of the first high-boiling fraction is between 450-600℃; Fischer-Tropsch synthesis wax is subjected to first hydroprocessing and second atmospheric and vacuum distillation to obtain a second high-boiling fraction; the distillation range of the second high-boiling fraction is between 470-700℃; the first high-boiling fraction and the second high-boiling fraction are mixed, subjected to second hydroprocessing and third atmospheric and vacuum distillation to obtain a third high-boiling fraction; the distillation range of the third high-boiling fraction is between 430-700℃; wherein, based on 100 parts by weight of the mixture of the first high-boiling fraction and the second high-boiling fraction, the content of the second high-boiling fraction is 30-60 parts by weight; the third high-boiling fraction is subjected to isomerization dewaxing, hydrofining and fourth atmospheric and vacuum distillation in sequence to obtain a fourth high-boiling fraction; the distillation range of the fourth high-boiling fraction is between 450-700℃; the fourth high-boiling fraction is mixed with an organic coagulant aid and subjected to solvent dewaxing; wherein, the organic coagulant aid is paraffin wax and / or microcrystalline wax, and based on 100 parts by weight of the mixture of the fourth high-boiling fraction and the organic coagulant aid, the content of the organic coagulant aid is 10-20 parts by weight.

2. The method of claim 1, wherein, based on the total weight of the first high-boiling fraction, the distillation point temperature of 5% by weight of the first high-boiling fraction is not lower than 450℃; the distillation point of 95% by weight of the first high-boiling fraction is not higher than 600℃; The properties of the first high-boiling fraction include: an open flash point of not less than 250°C, a carbon residue content of not more than 1.5% by weight, a freezing point of not less than 45°C, a kinematic viscosity at 100°C of not less than 12 mm 2 / s, a n-heptane insolubles content of not more than 200 μg / g, and a viscosity index of not less than 45.

3. The method of claim 2, wherein, based on the total weight of the first high-boiling fraction, the distillation point temperature of 5% by weight of the first high-boiling fraction is not lower than 460℃; the distillation point of 95% by weight of the first high-boiling fraction is not higher than 580℃; The properties of the first high-boiling fraction include: an open-cup flash point of not less than 260°C; a carbon residue content of not more than 1 wt%; a freezing point of not less than 50°C; a kinematic viscosity at 100°C of not less than 14 mm 2 / s; a n-heptane insolubles content of not more than 100 μg / g; a viscosity index of not less than 55.

4. The method of claim 3, wherein, based on the total weight of the first high-boiling fraction, the distillation point temperature of 5% by weight of the first high-boiling fraction is not lower than 470℃; the distillation point of 95% by weight of the first high-boiling fraction is not higher than 570℃; the properties of the first high-boiling fraction include: the n-heptane insoluble content is not higher than 80μg / g, and the viscosity index is not lower than 60.

5. The method of claim 1, wherein, The first hydroprocessing conditions include: hydrogen partial pressure of 5-14 MPa, reaction temperature of 260-380℃, liquid hourly space velocity of 0.4-2.0h -1 , hydrogen to oil volume ratio of (300-1200):

1.

6. The method of claim 5, wherein, The first hydroprocessing conditions include: hydrogen partial pressure of 6-12 MPa, reaction temperature of 280-360℃, liquid hourly space velocity of 0.6-1.5h -1 , hydrogen to oil volume ratio of (500-1000):

1.

7. The method of claim 6, wherein, The first hydroprocessing conditions include: hydrogen partial pressure of 6-10 MPa, reaction temperature of 300-350℃, liquid hourly space velocity of 0.8-1.2h -1 , hydrogen to oil volume ratio of (600-800):

1.

8. The method of claim 1, wherein, The properties of the second high-boiling fraction include: a carbon atom number of not less than 30, a kinematic viscosity at 100°C of not less than 28 mm 2 / s, a total metal content of not more than 20 μg / g, in which the iron ion content is not more than 10 μg / g, and a n-heptane insoluble content of not more than 200 μg / g.

9. The method of claim 8, wherein, The properties of the second high-boiling fraction include: a carbon atom number of not less than 33, a kinematic viscosity at 100°C of not less than 31 mm 2 / s, a total metal content of not more than 15 μg / g, in which the iron ion content is not more than 6 μg / g, and a n-heptane insoluble content of not more than 150 μg / g.

10. The method of claim 9, wherein, The properties of the second high-boiling fraction include: a carbon atom number of not less than 36, a kinematic viscosity at 100°C of not less than 33 mm 2 / s, a total metal content of not more than 10 μg / g, in which the iron ion content is not more than 3 μg / g, and a n-heptane insoluble content of not more than 100 μg / g.

11. The method of claim 1, wherein, The conditions of the second hydroprocessing include: hydrogen partial pressure of 8-18 MPa, reaction temperature of 330-420℃, liquid hourly space velocity of 0.2-1.4h -1 , hydrogen to oil volume ratio of (300-1200):

1.

12. The method of claim 11, wherein, The conditions of the second hydroprocessing include: hydrogen partial pressure of 12-18 MPa, reaction temperature of 350-400℃, liquid hourly space velocity of 0.3-1.2h -1 , hydrogen to oil volume ratio of (500-1000):

1.

13. The method of claim 12, wherein, The conditions of the second hydroprocessing include: hydrogen partial pressure of 14-18 MPa, reaction temperature of 350-380℃, liquid hourly space velocity of 0.4-0.8h -1 , hydrogen to oil volume ratio of (600-900):

1.

14. The method of claim 1, wherein, the properties of the third high-boiling fraction include: the sulfur content is not more than 30μg / g, and the nitrogen content is not more than 10μg / g.

15. The method of claim 14, wherein, the properties of the third high-boiling fraction include: the sulfur content is not more than 20μg / g, and the nitrogen content is not more than 5μg / g.

16. The method of claim 15, wherein, the properties of the third high-boiling fraction include: the sulfur content is not more than 15μg / g, and the nitrogen content is not more than 3μg / g.

17. The method of claim 1, wherein, The conditions of the isomerization dewaxing include: reaction temperature is 310-380℃, volume liquid hourly space velocity is 0.5-2.0h -1 -1, reaction pressure is 4-16MPa, hydrogen / oil volume ratio is (500-1200):1; The conditions of the hydrofining include: reaction temperature is 200-280℃, volume liquid hourly space velocity is 0.3-2h -1 , reaction pressure is 2-16MPa, hydrogen oil volume ratio is (500-1200):

1.

18. The method of claim 17, wherein, The conditions of the isomerization dewaxing include: reaction temperature is 320-380℃, volume liquid hourly space velocity is 0.6-1.4h -1 , reaction pressure is 6-14MPa, hydrogen oil volume ratio is (600-1000):1; The conditions of the hydrofining include: reaction temperature is 210-260℃, volume liquid hourly space velocity is 0.4-1.6h -1 , reaction pressure is 4-14MPa, hydrogen oil volume ratio is (600-1200):

1.

19. The method of claim 18, wherein, The conditions of the isomerization dewaxing include: reaction temperature is 350-375℃, volume liquid hourly space velocity is 0.8-1.2h -1 , reaction pressure is 8-14MPa, hydrogen oil volume ratio is (800-1000):1; The conditions of the hydrofining include: reaction temperature is 220-260℃, volume liquid hourly space velocity is 0.5-1h -1 , reaction pressure is 6-12MPa, hydrogen oil volume ratio is (800-1200):

1.

20. The method of claim 1, wherein, based on the total weight of the fourth high-boiling fraction, the distillation point temperature of 5% by weight of the fourth high-boiling fraction is not lower than 450℃; The properties of the fourth high-boiling fraction include kinematic viscosity at 100°C not less than 24 mm 2 / s, open flash point not less than 280°C, and pour point not higher than -18°C.

21. The method of claim 20, wherein, based on the total weight of the fourth high-boiling fraction, the distillation point temperature of 5% by weight of the fourth high-boiling fraction is not lower than 500℃; The properties of the fourth high-boiling fraction include: kinematic viscosity at 100°C not less than 28 mm 2 / s, open flash point not less than 290°C, and pour point not higher than -20°C.

22. The method of claim 1, wherein, the conditions of the solvent dewaxing include: the solvent is a mixture of methyl ethyl ketone-toluene; the filtration temperature is -25℃ to 20℃.

23. The method of claim 22, wherein, the conditions of the solvent dewaxing include: the filtration temperature is -20℃ to 15℃.

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