A system and method for hydroprocessing of used lubricating oil

Abstract

The present disclosure relates to a system and method for waste lubricating oil hydrogenation regeneration, which comprises: S1, contacting waste lubricating oil, carbon carrier catalyst and promoter in a slurry bed for hydrogenation pretreatment to obtain a hydrogenation mixture; S2, performing solid-liquid separation on the hydrogenation mixture to obtain waste agent and lubricating oil base oil fraction; S3, contacting the lubricating oil base oil fraction with a first hydrogenation catalyst in a medium-pressure fixed-bed hydrogenation device for medium-pressure hydrogenation reaction to obtain a medium-pressure hydrogenation product; S4, fractionating the medium-pressure hydrogenation product to obtain gas, distillate oil, light lubricating oil fraction and heavy lubricating oil fraction; and S5, contacting the light lubricating oil fraction and the heavy lubricating oil fraction with a second hydrogenation catalyst respectively in a high-pressure fixed-bed hydrogenation device for high-pressure hydrogenation reaction. The method of the present disclosure can remove chlorine and heavy metals while ensuring high liquid yield, and the recovery rate of lubricating oil base oil and bright stock is high and the quality is good.

Description

Technical Field

[0001] This disclosure relates to a system and method for the hydrogenation regeneration of waste lubricating oil. Background Technology

[0002] In recent years, the consumption of lubricating oil products has been increasing year by year. In 2023, my country's apparent consumption of lubricating oil was approximately 7.48 million tons, which will generate approximately 4.7 million tons of waste lubricating oil. Researching and developing methods suitable for the regeneration of waste lubricating oil has significant social and economic benefits and huge market potential. Therefore, the recycling of waste lubricating oil has received widespread attention in recent years, with the expectation that recycled oil will reach the quality level of new lubricating oil base oil.

[0003] The development of waste lubricating oil regeneration processes has generally gone through stages such as the acid-earth method (sulfuric acid-clay process), the acid-free method (distillation-clay process), and the distillation-hydrogenation method. The biggest drawback of traditional waste lubricating oil recycling technologies is that the waste generated during the process easily pollutes the environment. Currently, many oil companies both domestically and internationally are researching and developing new waste lubricating oil hydrogenation recovery technologies. To date, representative technologies include the distillation-solvent refining-hydrogenation refining type, the demetallization-fixed-bed hydrogenation refining type, and the distillation-hydrogenation refining type.

[0004] Various mechanical equipment places increasingly higher demands on the performance of lubricating oil products. To meet the stringent operating conditions of these machines, manufacturers are adding more and more additives to their finished lubricating oils, such as antioxidants, anti-wear agents, friction modifiers, extreme pressure additives, detergents, dispersants, foaming agents, corrosion and rust inhibitors, flow improvers, pour point depressants, and viscosity index promoters. These additives typically contain metallic compounds such as calcium, zinc, copper, and barium. Because waste oil contains heavy metal compounds from these additives, these compounds can easily deposit on the surface of the hydrogenation catalyst during hydrogenation reactions, causing rapid catalyst poisoning, deactivation, and shortened lifespan. They can also easily deposit on the outer surface of catalyst particles or accumulate between particles, leading to catalyst bed agglomeration and blockage, resulting in a rapid increase in reactor pressure drop and shutdown. Furthermore, due to the diverse sources of waste lubricating oil and its complex composition, especially its high metal content, hydrogenation technologies commonly suffer from equipment blockage and corrosion, placing higher demands on the continuity of the production process and the stability of long-term operation. Therefore, effectively removing heavy metals, avoiding their impact on catalysts and equipment, and ensuring stable long-term operation of the hydrogenation process are the challenges of waste lubricating oil regeneration technology.

[0005] CN106398765A discloses a method for the hydrogenation and recycling of waste lubricating oil. The process includes: removing mechanical impurities from the waste lubricating oil and then flash-separating free water and some light hydrocarbons; mixing the bottom material of the flash tower with hydrogen and a self-sulfurized oil-soluble transition metal catalyst, followed by hydrogen pretreatment in a slurry bed reactor; separating the liquid product from the reaction effluent, and then removing solid residues through hydrocyclone separation and solvent washing to obtain pretreated lubricating oil components; mixing these components with hydrogen and then entering a series of hydrorefining reactors—an isomerization dewaxing reactor and a supplementary refining reactor—for hydrogenation treatment; and separating the reaction products to obtain high-quality naphtha, diesel oil, and lubricating oil base oil. This method involves a single-pass flow of the oil-soluble catalyst, resulting in low utilization, and requires solvent recovery after hydrocyclone separation, making the process complex and energy-intensive. Summary of the Invention

[0006] The purpose of this disclosure is to provide a system and method for the hydrogenation regeneration of waste lubricating oil, which can remove chlorine and heavy metals while ensuring high liquid recovery, and achieve high recovery rates and good quality of lubricating oil base oil and bright oil.

[0007] To achieve the above objectives, the first aspect of this disclosure provides a method for hydroregeneration of lubricating oil, the method comprising:

[0008] S1. Waste lubricating oil, carbon-supported catalyst and accelerator are contacted in a slurry bed for hydrogenation pretreatment to obtain a hydrogenated mixture;

[0009] S2. Perform solid-liquid separation on the hydrogenated mixture to obtain waste agent and lubricating oil base oil fraction;

[0010] S3. In a medium-pressure fixed-bed hydrogenation unit, the lubricating oil base oil fraction is brought into contact with the first hydrogenation catalyst to carry out a medium-pressure hydrogenation reaction to obtain a medium-pressure hydrogenation product.

[0011] S4. The medium-pressure hydrogenation product is fractionated so that the obtained lubricating oil fraction is contacted with the second hydrogenation catalyst in a high-pressure fixed-bed hydrogenation unit to carry out a high-pressure hydrogenation reaction.

[0012] Optionally, in step S1, the conditions for the hydrogen pretreatment include: a reaction temperature of 300-480℃; a reaction pressure of 2-25 MPa; and a liquid hourly space velocity of 0.2-4 h⁻¹. -1 The volume ratio of hydrogen to the waste lubricating oil is 100-3000 Nm³. 3 / m 3 .

[0013] Optionally, in step S1, the carbon-supported catalyst comprises a carbon-based support and an active metal component; based on the total weight of the carbon-supported catalyst and calculated by metal element, the content of the active metal component is 1-50% by weight.

[0014] The carbon-based carrier comprises carbon-containing materials with a carbon content greater than 80% by weight; the metal elements in the active metal component include one or more of Fe, Co, Mo, W and Ni.

[0015] Optionally, in step S1, the amount of the carbon-supported catalyst, calculated as metal element, relative to 1g of the waste lubricating oil is 20-10000μg, preferably 50-5000μg, and more preferably 100-3000μg.

[0016] Optionally, in step S1, the accelerator contains a sulfur-containing substance; preferably, the sulfur-containing substance is selected from one or more of carbon disulfide, sulfur, dimethyl disulfide and di-tert-butyl polysulfide.

[0017] The amount of the accelerator is 10-20000 μg relative to 1g of the waste lubricating oil, preferably 50-6000 μg.

[0018] Optionally, in step S3, the conditions for the medium-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-20 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm. 3 / m 3 The reaction temperature is 260-380℃, and the volume hourly space velocity is 0.2-5h. -1 ;

[0019] Preferably, the hydrogen partial pressure is 5-12 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature is 280-360℃, and the volume hourly space velocity is 0.3-3h. -1 .

[0020] Optionally, in step S3, along the flow direction of the lubricating oil base oil fraction, the first hydrogenation catalyst includes catalyst A, catalyst B and catalyst C arranged sequentially; by volume and based on the total volume of the first hydrogenation catalyst, the content of catalyst A in the first hydrogenation catalyst is 5-20%, the content of catalyst B is 10-50%, and the content of catalyst C is 30-85%.

[0021] The catalyst A contains a first hydrogenation active metal and a first support; the first hydrogenation active metal includes a Group VIB metal and optionally a Group VIII metal, and the first support is selected from alumina and / or silica; the first support contains phosphorus, and the phosphorus content, based on the total weight of the first support and calculated as P2O5, is 0.1-8.0% by weight; based on the total weight of the catalyst A and calculated as oxides, the content of the Group VIB metal is greater than 0 and less than 10% by weight, and the content of the Group VIII metal is 0.2-5% by weight;

[0022] The catalyst B contains a second hydrogenation active metal and a second support; the second hydrogenation active metal includes a Group VIB metal and optionally a Group VB metal, and the second support is selected from alumina and / or silicon oxide; the second support contains phosphorus and halogens, with the phosphorus content (based on the total weight of the second support, calculated as P2O5) being 0.1-8.0% by weight and the halogen content (based on the element) being 0.1-6% by weight; based on the total weight of the catalyst B and calculated as oxides, the content of the Group VIB metal is greater than 0.2% and less than 12% by weight, and the content of the Group VB metal is 0-12% by weight;

[0023] The catalyst C contains a third hydrogenation active metal and a third support; the third hydrogenation active metal includes Group VIB metals and optionally Group VIII metals, and the third support is selected from alumina and / or silicon oxide; the third support contains phosphorus and halogens, with the phosphorus content (based on the total weight of the third support, calculated as P2O5) being 0.1-8.0% by weight and the halogen content (based on the elemental content) being 0.1-6% by weight; based on the total weight of the catalyst C and calculated as oxides, the content of the Group VIB metal is 0.2-10% by weight and the content of the Group VIII metal is less than 5% by weight;

[0024] Preferably, the volume ratio of catalyst A, catalyst B and catalyst C is 1:(1-10):(1.5-17), more preferably 1:(2-5):(3-15).

[0025] Optionally, in step S4, the fractionation conditions include: a pressure of -90 kPa to -99 kPa and a bottom temperature of 320-370 °C.

[0026] The cutoff point between the distillate oil and the light lubricating oil fraction is 300-320℃; the cutoff point between the light lubricating oil fraction and the heavy lubricating oil fraction is 500-540℃.

[0027] Optionally, in step S5, along the flow direction of the light lubricating oil fraction and the heavy lubricating oil fraction, the second hydrogenation catalyst includes catalyst I and catalyst II in sequence;

[0028] The catalyst I comprises a hydrogenation catalyst Ia, which contains a first promoter, a fourth hydrogenation active metal component, and a fourth support; the first promoter comprises one or more of fluorine, boron, and phosphorus; the metal element in the first hydrogenation active metal component comprises one or more of Co, Mo, Ni, and W; the fourth support is selected from alumina and / or silicon oxide; based on the dry weight of the hydrogenation catalyst Ia, the content of the fourth hydrogenation active metal component, calculated as metal oxide, is 22-32% by weight, and the content of the first promoter is 3-10% by weight;

[0029] Preferably, the catalyst I further includes a hydrogenation catalyst Ib disposed upstream of the hydrogenation catalyst Ia; the hydrogenation catalyst Ib contains a fifth hydrogenation active metal component and a fifth support, and the content of the fifth hydrogenation active metal component is 2-15% by weight based on the dry weight of the hydrogenation catalyst Ib; the fifth hydrogenation active metal component is selected from one or more of Co, Mo, Ni and W; the fifth support is selected from alumina and / or silicon oxide;

[0030] Preferably, the volume ratio of the hydrogenation catalyst Ia to the hydrogenation catalyst Ib is (3-10):1.

[0031] Optionally, in step S5, the second hydrogenation catalyst further includes catalyst II disposed downstream of catalyst I;

[0032] Catalyst II comprises a second promoter, a sixth hydrogenation active metal component, and a sixth support; the second promoter contains boron and / or phosphorus, and the content of the sixth hydrogenation active metal component, calculated as metal oxide, is 22-36% by weight based on the dry weight of catalyst II; the content of the second promoter is 2-8% by weight; the sixth hydrogenation active metal component is selected from one or more of Co, Mo, Ni, and W; the sixth support is selected from alumina and / or silicon oxide; the hydrogenation catalyst II is a fluorine-free hydrogenation catalyst; the content of the sixth hydrogenation active metal component of the hydrogenation catalyst II is greater than or equal to the content of the fourth hydrogenation active metal component of the hydrogenation catalyst Ia;

[0033] Preferably, the volume ratio of catalyst I to catalyst II is (30:70)-(60:40).

[0034] Optionally, in step S5, the conditions for the high-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-25 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm. 3 / m 3 The reaction temperature of catalyst I is 260-420℃, and the volume hourly space velocity is 0.2-3h. -1The reaction temperature of catalyst II is 240-380℃, and the volume hourly space velocity is 0.2-3h. -1 ;

[0035] Preferably, the hydrogen partial pressure is 5-20 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature of catalyst I is 280-360℃, and the volume hourly space velocity is 0.3-2h. -1 The reaction temperature of catalyst II is 260-340℃, and the volume hourly space velocity is 0.3-2h. -1 .

[0036] The second aspect of this disclosure provides a system for hydrogenation regeneration of waste lubricating oil used in the first aspect of this disclosure. The system includes: a slurry bed, a solid-liquid separation device, a medium-pressure fixed-bed hydrogenation device, a fractionation tower, and a high-pressure fixed-bed hydrogenation device.

[0037] The product outlet of the slurry bed is fluidly connected to the inlet of the solid-liquid separation device, the liquid outlet of the solid-liquid separation device is fluidly connected to the inlet of the medium-pressure fixed-bed hydrogenation device, the outlet of the medium-pressure fixed-bed hydrogenation device is fluidly connected to the inlet of the fractionation tower, and the outlets of the light lubricating oil fraction and the heavy lubricating oil fraction of the fractionation tower are each independently fluidly connected to the inlet of the high-pressure fixed-bed hydrogenation device.

[0038] The advantages of this disclosure through the above technical solution are as follows:

[0039] (1) This disclosure uses a slurry bed to perform hydropretreatment on the entire fraction of waste lubricating oil, which can effectively remove metal and non-metal heteroatoms from the waste oil and saturate some polycyclic aromatic hydrocarbons, reducing the severity of subsequent processing and improving the operating cycle of the subsequent fixed bed unit. At the same time, the carbon-supported catalyst used can effectively reduce the catalyst cost while ensuring the recovery and impurity removal requirements of the hydropretreatment liquid.

[0040] (2) After the slurry bed reaction, the medium-pressure fixed bed hydrogenation can further transform the impurities that have not been transformed in the slurry bed reaction, protect the stable operation of the subsequent high-pressure fixed bed hydrogenation reaction system, and avoid the situation where the uncertainty of the source of waste lubricating oil causes fluctuations in the previous slurry bed hydrogenation reaction, poor impurity removal effect, which leads to poor effect of subsequent high-pressure hydrogenation or forced shutdown.

[0041] (3) In this disclosure, light lubricating oil fraction and heavy lubricating oil base oil fraction are subjected to high-pressure fixed-bed hydrogenation, and different hydrogenation conditions and product fractionation conditions are adopted to enhance the aromatic saturation of the product. The hydrogenation feedstock is subjected to a first fractionation-then hydrogenation-then fractionation method to prevent the heavy base oil after hydrogenation from oxidizing and deteriorating due to excessively high fractionation temperature during the product fractionation stage, thereby ensuring the long-term operation of the catalyst and the improvement of product quality.

[0042] (4) The method disclosed herein can produce bright oil products with high recovery rate and good quality of light lubricating oil base oil and bright oil.

[0043] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0044] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0045] Figure 1 This is a flowchart illustrating a specific embodiment of the waste lubricating oil hydrogenation regeneration method disclosed herein. Detailed Implementation

[0046] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0047] like Figure 1 As shown, the first aspect of this disclosure provides a method for hydrogenating and regenerating waste lubricating oil. The method includes: S1, contacting waste lubricating oil, a carbon-supported catalyst, and an accelerator in a slurry bed for hydrogen pretreatment to obtain a hydrogenated mixture; S2, performing solid-liquid separation on the hydrogenated mixture to obtain waste catalyst and lubricating oil base oil fraction; S3, in a medium-pressure fixed-bed hydrogenation device, contacting the lubricating oil base oil fraction with a first hydrogenation catalyst for a medium-pressure hydrogenation reaction to obtain a medium-pressure hydrogenation product; S4, fractionating the medium-pressure hydrogenation product to obtain gas, distillate oil, light lubricating oil fraction, and heavy lubricating oil fraction; S5, in a high-pressure fixed-bed hydrogenation device, contacting the light lubricating oil fraction and the heavy lubricating oil fraction with a second hydrogenation catalyst for a high-pressure hydrogenation reaction.

[0048] This disclosed method employs a slurry bed for hydrogenation pretreatment of the entire fraction of waste lubricating oil, effectively removing metal and non-metal heteroatoms from the waste oil and saturating some polycyclic aromatic hydrocarbons, thus reducing the severity of subsequent processing and improving the operating cycle of the subsequent fixed-bed unit. Simultaneously, the carbon-supported catalyst used effectively reduces catalyst costs while ensuring the recovery and impurity removal requirements of the hydrogenation pretreatment liquid. This disclosure separately hydrogenates the light lubricating oil fraction and the heavy lubricating oil base oil fraction in a high-pressure fixed bed, ensuring long-term catalyst operation and improved product quality, resulting in high recovery rates and high quality of lubricating oil base oil and bright oil.

[0049] In one specific embodiment of this disclosure, the conditions for the hydrogen pretreatment in step S1 include: a reaction temperature of 300-480℃; a reaction pressure of 2-25 MPa; and a liquid hourly space velocity of 0.2-4 h⁻¹. -1 The volume ratio of hydrogen to the waste lubricating oil (i.e., the hydrogen-to-oil volume ratio) is 100-3000 Nm³. 3 / m 3 Preferably, the reaction temperature is 350-420℃, the reaction pressure is 3-18MPa, and the liquid hourly space velocity is 0.3-2h. -1 The volume ratio of hydrogen to the waste lubricating oil is 300-3000 Nm³. 3 / m 3 In this disclosure, by controlling the reaction conditions of hydrogen pretreatment and using a carbon-supported catalyst, the conversion rate of the lubricating oil base oil fraction (280-520℃) in waste lubricating oil can be kept below 15%, and the yield of the lubricating oil base oil fraction obtained from the regeneration process is high.

[0050] In one specific embodiment of this disclosure, in step S1, the carbon-supported catalyst comprises a carbon-based support and an active metal component; based on the total weight of the carbon-supported catalyst and calculated by metal element, the content of the active metal component is 1-50% by weight, preferably 5-40% by weight, and more preferably 20-40% by weight; the carbon-based support comprises carbon-containing materials with a carbon content greater than 80% by weight, and the carbon-based support may include, but is not limited to, carbon black, activated carbon, coal powder, deoiled asphalt, etc.; the metal element in the active metal component includes one or more of Fe, Co, Mo, W and Ni, and preferably, the active metal component includes metal oxides.

[0051] According to this disclosure, the accelerator contains a sulfur-containing substance well known to those skilled in the art, such as one or more of carbon disulfide, sulfur, dimethyl disulfide, and di-tert-butyl polysulfide. The amount of the accelerator relative to 1g of the waste lubricating oil is 10-20000μg, preferably 50-6000μg.

[0052] In one specific embodiment of this disclosure, in step S1, the amount of the carbon-supported catalyst, calculated as metal element, is 20-10000 μg, preferably 50-5000 μg, and more preferably 100-3000 μg, relative to 1g of the waste lubricating oil.

[0053] In one specific embodiment of this disclosure, in step S1, superheated steam and / or alkaline solution are introduced into the slurry bed to slow down coking in the heating furnace and to facilitate the dechlorination treatment of waste lubricating oil.

[0054] According to this disclosure, in step S2, the solid-liquid separation can be performed using methods well known to those skilled in the art, such as one or more combinations of filtration separation, centrifugal separation, membrane separation, and solvent extraction separation. In one specific embodiment of this disclosure, the solid-liquid separation is performed using solvent extraction separation, in which the hydrogenated mixture is contacted with an extractant for solvent extraction separation; the conditions for solvent extraction separation include: a temperature of 40-300°C; a pressure of 0.1-14 MPa; and the amount of extractant used relative to 1 part by weight of the hydrogenated mixture is 1-10 parts by weight, preferably 1-5 parts by weight. The extractant can be anything well known to those skilled in the art, such as at least one of C3-C8 alkanes, C3-C8 olefins, toluene, and light naphtha, preferably selected from C3-C5 alkanes and / or toluene.

[0055] In one specific embodiment of this disclosure, the total metal content of the lubricating oil base oil fraction obtained in step S2 is not greater than 20 μg / g, the content of n-heptane insoluble matter is not greater than 100 μg / g, and the chlorine content is 1-50 μg / g.

[0056] According to this disclosure, there can be one or more medium-pressure hydrogenation units, with multiple medium-pressure hydrogenation units connected in series. In one specific embodiment of this disclosure, in step S3, the conditions for the medium-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-20 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm³. 3 / m 3 The reaction temperature is 260-380℃, and the volume hourly space velocity is 0.2-5h. -1 Preferably, the hydrogen partial pressure is 5-12 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature is 280-360℃, and the volume hourly space velocity is 0.3-3h. -1 .

[0057] According to this disclosure, a medium-pressure fixed-bed hydrogenation unit employs a variety of catalyst gradations. In one specific embodiment of this disclosure, in step S3, along the flow direction of the lubricating oil base oil fraction, the first hydrogenation catalyst comprises catalyst A, catalyst B, and catalyst C arranged sequentially; by volume and based on the total volume of the first hydrogenation catalyst, the content of catalyst A in the first hydrogenation catalyst is 5-20%, the content of catalyst B is 10-50%, and the content of catalyst C is 30-85%.

[0058] The catalyst A contains a first hydrogenation active metal and a first support; the first hydrogenation active metal includes a Group VIB metal and optionally a Group VIII metal, and the first support is selected from alumina and / or silica; the first support contains phosphorus, and the phosphorus content, based on the total weight of the first support and calculated as P2O5, is 0.1-8.0% by weight; based on the total weight of the catalyst A and calculated as oxides, the content of the Group VIB metal is greater than 0 and less than 10% by weight, preferably 0.5-8% by weight, and the content of the Group VI II metal is 0.2-5% by weight, preferably 0.3-4% by weight.

[0059] The catalyst B contains a second hydrogenation active metal and a second support; the second hydrogenation active metal includes a Group VIB metal and optionally a Group VB metal, and the second support is selected from alumina and / or silicon oxide; the second support contains phosphorus and halogens, and based on the total weight of the second support, the phosphorus content, calculated as P2O5, is 0.1-8.0% by weight, preferably 0.2-5% by weight, and the halogen content, calculated as an element, is 0.1-6% by weight, preferably 0.2-5% by weight; based on the total weight of the catalyst B and calculated as oxides, the content of the Group VIB metal is greater than 0.2% and less than 12% by weight, and the content of the Group VB metal is 0-12% by weight.

[0060] The catalyst C contains a third hydrogenation active metal and a third support; the third hydrogenation active metal includes Group VIB metals and optionally Group VIII metals, and the third support is selected from alumina and / or silicon oxide; the third support contains phosphorus and halogen elements, and based on the total weight of the third support, the phosphorus content, calculated as P2O5, is 0.1-8.0% by weight, preferably 0.2-5% by weight, and the halogen content, calculated as an element, is 0.1-6% by weight, preferably 0.2-5% by weight; based on the total weight of the catalyst C and calculated as oxides, the content of the Group VIB metal is 0.2-10% by weight, and the content of the Group VIII metal is less than 5% by weight.

[0061] In a preferred embodiment of this disclosure, the volume ratio of catalyst A, catalyst B and catalyst C is 1:(1-10):(1.5-17), preferably 1:(2-5):(3-15).

[0062] In one specific embodiment of this disclosure, in step S4, the fractionation conditions include: a pressure of -90 kPa to -99 kPa, a bottom temperature of 320-370°C; the cutoff point between the distillate oil and the light lubricating oil fraction is 300-320°C; and the cutoff point between the light lubricating oil fraction and the heavy lubricating oil fraction is 500-540°C. In one embodiment, the distillation range of the light lubricating oil fraction is 300-540°C, preferably 320-520°C; and the distillation range of the heavy lubricating oil fraction is greater than 500°C, preferably greater than 520°C.

[0063] In one specific embodiment of this disclosure, in step S5, along the flow direction of the light lubricating oil fraction and the heavy lubricating oil fraction, the second hydrogenation catalyst includes catalyst I and catalyst II in sequence;

[0064] The catalyst I comprises a hydrogenation catalyst Ia, which contains a first promoter, a fourth hydrogenation active metal component, and a fourth support; the first promoter comprises one or more of fluorine, boron, and phosphorus; the metal element in the first hydrogenation active metal component comprises one or more of Co, Mo, Ni, and W; the fourth support is selected from alumina and / or silicon oxide; based on the dry weight of the hydrogenation catalyst Ia, the content of the fourth hydrogenation active metal component, calculated as metal oxide, is 22-32% by weight, and the content of the first promoter is 3-10% by weight.

[0065] In one specific embodiment of this disclosure, in step S5, the catalyst I further includes a hydrogenation catalyst Ib disposed upstream of the hydrogenation catalyst Ia; the hydrogenation catalyst Ib contains a fifth hydrogenation active metal component and a fifth support, and the content of the fifth hydrogenation active metal component is 2-15% by weight based on the dry basis weight of the hydrogenation catalyst Ib; the fifth hydrogenation active metal component is selected from one or more of Co, Mo, Ni and W; the fifth support is selected from alumina and / or silicon oxide;

[0066] Preferably, the volume ratio of the hydrogenation catalyst Ia to the hydrogenation catalyst Ib is (3-10):1.

[0067] In one specific embodiment of this disclosure, the second hydrogenation catalyst further includes a catalyst II disposed downstream of the catalyst I; the catalyst II contains a second promoter, a sixth hydrogenation active metal component, and a sixth support; the second promoter contains boron and / or phosphorus, and the content of the sixth hydrogenation active metal component, based on the dry weight of the catalyst II and calculated as metal oxide, is 22-36% by weight; the content of the second promoter is 2-8% by weight; the sixth hydrogenation active metal component is selected from one or more of Co, Mo, Ni, and W; the sixth support is selected from alumina and / or silicon oxide; the hydrogenation catalyst II is a fluorine-free hydrogenation catalyst; the content of the sixth hydrogenation active metal component of the hydrogenation catalyst II is greater than or equal to the content of the fourth hydrogenation active metal component of the hydrogenation catalyst Ia; preferably, the volume ratio of the catalyst I and the catalyst II is (30:70)-(60:40).

[0068] In a preferred embodiment of this disclosure, the catalyst II is a fluorine-free hydrogenation catalyst, which can be commercially available or prepared in-house. Commercially available catalyst II can be, for example, a catalyst with the designation RJW-2 or RJW-3.

[0069] The method disclosed herein employs a high-performance first and second hydrogenation catalyst and uses a novel catalyst gradation scheme, which can prevent the pressure drop of the fixed-bed hydrogenation reactor from rising rapidly, extend the operating cycle of the unit, and improve product quality.

[0070] In one specific embodiment of this disclosure, the method further includes step S6: introducing the reaction product obtained from the high-pressure hydrogenation reaction into a product fractionation tower for fractionation. Preferably, the light lubricating oil fraction obtained in step S5 is stored in a storage tank, and / or the heavy lubricating oil fraction obtained in step S5 is stored in a storage tank, so that the light lubricating oil fraction and the heavy lubricating oil fraction are respectively fed into a high-pressure fixed-bed hydrogenation unit to contact with the second hydrogenation catalyst for high-pressure hydrogenation reaction. This can reduce the bottom temperature of the product fractionation tower, prevent the formation of unstable substances at high temperatures, and improve the product color and stability.

[0071] According to this disclosure, there can be one or more high-pressure hydrogenation devices, with multiple high-pressure hydrogenation devices connected in series. In one specific embodiment of this disclosure, in step S5, the conditions for the high-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-25 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm³. 3 / m 3 The reaction temperature of catalyst I is 260-420℃, and the volume hourly space velocity is 0.2-3h. -1 The reaction temperature of catalyst II is 240-380℃, and the volume hourly space velocity is 0.2-3h. -1Preferably, the hydrogen partial pressure is 5-20 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature of catalyst I is 280-360℃, and the volume hourly space velocity is 0.3-2h. -1 The reaction temperature of catalyst II is 260-340℃, and the volume hourly space velocity is 0.3-2h. -1 .

[0072] In one specific embodiment of this disclosure, the method further includes step S6: fractionating the reaction product obtained by high-pressure hydrogenation reaction to obtain lubricating oil base oil.

[0073] In this disclosure, the reaction pressure of the medium-pressure hydrogenation reaction is lower than that of the high-pressure hydrogenation reaction.

[0074] like Figure 1 As shown, the second aspect of this disclosure provides a system for the hydrogenation regeneration of waste lubricating oil using the method provided in the first aspect of this disclosure. The system includes: a slurry bed, a solid-liquid separation device, a medium-pressure fixed-bed hydrogenation device, a fractionation tower, and a high-pressure fixed-bed hydrogenation device. The product outlet of the slurry bed is fluidly connected to the inlet of the solid-liquid separation device; the liquid outlet of the solid-liquid separation device is fluidly connected to the inlet of the medium-pressure fixed-bed hydrogenation device; the outlet of the medium-pressure fixed-bed hydrogenation device is fluidly connected to the inlet of the fractionation tower; and the outlets of the light lubricating oil fraction and the heavy lubricating oil fraction of the fractionation tower are each independently fluidly connected to the inlet of the high-pressure fixed-bed hydrogenation device.

[0075] The present disclosure is further described in detail below through examples.

[0076] The properties of the waste lubricating oil regenerated in the following examples and comparative examples are shown in Table 1. Unless otherwise specified, all reagents used were commercially available.

[0077] Table 1 Properties of waste lubricating oil

[0078]

[0079]

[0080] The carbon-supported catalyst C1 in the slurry bed was prepared by the following method:

[0081] (1) Preparation of carrier: Activated carbon (carbon content of more than 95% by weight) is dried and dehydrated at 120℃ and then pulverized into powder with a particle size of 20-60μm;

[0082] (2) Using Fe2(SO4)3 to prepare an aqueous solution of ferric sulfate as the metal source solution, the Fe content in the aqueous solution of ferric sulfate is 2.4g relative to 100mL of active metal source solution; after mixing 125mL of aqueous solution of ferric sulfate with 5g of carrier evenly, 20.16g of 28wt% ammonia solution is added while stirring to carry out precipitation reaction; the precipitation reaction conditions are: reaction temperature of 60℃ and reaction time of 60min; after the precipitation is washed, the precipitation reaction product is subjected to solid-liquid separation to obtain solid material;

[0083] (3) After drying the solid material at 110℃ for 300 min, it was placed in a tube furnace and calcined at 490℃ for 300 min under N2 gas protection to obtain carbon-supported catalyst C1, the properties of which are shown in Table 2.

[0084] The preparation method of carbon-supported catalyst C2 is similar to that of carbon-supported catalyst C1. The difference is that in step (3), carbon-supported catalyst C2 is obtained after drying at 110℃ for 300 min and is no longer placed in a tube furnace for calcination. Its properties are shown in Table 2.

[0085] Table 2 Properties of carbon-supported catalysts C1 and C2

[0086] Fe, weight % <![CDATA[Specific surface area, m 2 / g]]> Particle size, μm metallic phase Metal particle size, nm C1 35.40 50.3 24.5 <![CDATA[Fe3O4]]> 22.37 C2 27.75 51.7 29.3 <![CDATA[Fe(OH)3]]> 31.59

[0087] Example 1

[0088] S1. Waste lubricating oil, carbon-supported catalyst C1 and accelerator are mixed and introduced into a slurry bed for hydrogenation pretreatment to obtain a hydrogenated mixture;

[0089] S2. Perform solid-liquid separation on the hydrogenated mixture to obtain waste agent and lubricating oil base oil fraction;

[0090] S3. In a medium-pressure fixed-bed hydrogenation unit, the lubricating oil base oil fraction is brought into contact with the first hydrogenation catalyst to carry out a medium-pressure hydrogenation reaction to obtain the medium-pressure hydrogenation product.

[0091] S4. The medium-pressure hydrogenation product is fractionated to obtain gas, distillate oil, light lubricating oil fraction and heavy lubricating oil fraction;

[0092] S5. In the high-pressure fixed-bed hydrogenation unit, the light lubricating oil fraction and the heavy lubricating oil fraction are respectively contacted with the second hydrogenation catalyst to carry out high-pressure hydrogenation reaction. The high-pressure hydrogenation reaction product of the light lubricating oil fraction is introduced into the product fractionation tower for separation to obtain the medium lubricating oil product; the high-pressure hydrogenation reaction product of the heavy lubricating oil fraction is introduced into the product fractionation tower for separation to obtain the heavy lubricating oil product.

[0093] The reaction conditions, product results, and product property analysis results for the above steps are shown in Tables 5 and 6.

[0094] Along the flow direction of the lubricating oil base oil fraction, the first hydrogenation catalyst includes catalyst A, catalyst B and catalyst C arranged in sequence, and the composition of the catalyst is shown in Table 3.

[0095] Catalyst A contains 3.0 wt% MoO3, 0.5 wt% NiO and the balance support, wherein the P2O5 content in the support accounts for 3.5 wt% of the support.

[0096] The alumina was prepared as follows: 2 L of aluminum sulfate solution with an Al2O3 concentration of 90 g / L was prepared, and 6 mL of concentrated phosphoric acid was added to obtain a phosphorus-containing aluminum sulfate solution. The phosphorus-containing aluminum sulfate solution and an 8% ammonia solution were added concurrently to a 5 L reaction vessel to allow precipitation. The precipitate was then filtered (XRD characterization showed the hydrated alumina precipitate to be amorphous). The reaction temperature was 45 °C, and the flow rate of the ammonia solution was controlled to maintain the pH of the reaction system at 6.0. In a 5-liter reaction vessel, filter cake, deionized water, and ammonium bicarbonate were mixed and slurried. The amount of ammonia added was adjusted to a pH of 9.2. The slurry was aged at 40°C for 240 minutes and then filtered. The filter cake was washed twice with deionized water and dried at 120°C for 14 hours to obtain hydrated alumina P1. XRD characterization showed that P2 had a boehmite-like structure. P1 was calcined at 600°C for 4 hours to obtain alumina A1. XRD characterization showed that A1 had a γ-alumina structure. 1000 grams of the prepared hydrated alumina P1 was weighed and added to 1440 ml of an aqueous solution containing 10 ml of nitric acid (a product of Tianjin Chemical Reagent Factory No. 3). The mixture was extruded on a twin-screw extruder to form a product with an outer diameter of... The butterfly-shaped strips were dried at 120°C for 4 hours to obtain a molded product. The molded product was then calcined at 600°C for 3 hours to obtain support Z1. 200 g of support Z1 was impregnated with 220 mL of a mixed solution of ammonium heptamolybdate and nickel nitrate with a MoO3 content of 28.8 g / L and a NiO5 content of g / L for 1 hour, dried at 120°C for 4 hours, and calcined at 400°C for 3 hours to obtain catalyst A.

[0097] Catalyst B contains 8.0 wt% MoO3, 1.6 wt% V2O5, and the balance support. Based on the dry weight of the support, the phosphorus content (calculated as P2O5) is 4.9 wt%, and the halogen content (calculated as fluorine) is 1.0 wt%.

[0098] The preparation method is as follows: 2 L of aluminum sulfate solution with an Al2O3 concentration of 50 g / L was prepared, and 5 mL of concentrated phosphoric acid (85% by weight, the same below) was added to obtain a phosphorus-containing aluminum sulfate solution. The above aluminum sulfate solution and an 8% ammonia solution were added concurrently to a 5 L reaction vessel for precipitation. The mixture was then filtered (XRD characterization showed the hydrated alumina precipitate to be amorphous). The reaction temperature was 40 °C, and the flow rate of the ammonia solution was controlled to maintain the pH of the reaction system at 5.5. In another 5 L reaction vessel, filter cake, deionized water, and ammonia were mixed and slurried. The amount of ammonia used was adjusted to maintain the pH of the slurry at 8.0. The slurry was aged at 65 °C for 60 minutes and then filtered. The filter cake was then treated with deionized water... The alumina was slurryed and washed twice with water, and the filter cake was dried at 120℃ for 24 hours to obtain hydrated alumina P2. P2 was calcined at 600℃ for 4 hours to obtain alumina A2. XRD characterization showed that P2 had a pseudoboehmite structure, and A2 had a γ-alumina structure. 1000g of the prepared hydrated alumina P2 was weighed and added to 1440ml of an aqueous solution containing 10ml of nitric acid (from Tianjin Chemical Reagent Factory No. 3) and 9.8g of ammonium fluoride. The solution was extruded into a butterfly-shaped strip with an outer diameter of φ1.4mm on a twin-screw extruder. The wet strip was dried at 120℃ for 4 hours to obtain a molded product. This molded product was calcined at 600℃ for 3 hours to obtain support Z2. 200g of support Z2 was impregnated in 220ml of a mixed solution of ammonium heptamolybdate and ammonium vanadate containing 80g / L MoO3 and 16g / L V2O5 for 1 hour, dried at 120℃ for 4 hours, and calcined at 400℃ for 3 hours to obtain catalyst B.

[0099] Catalyst C contains 8.0 wt% WO3, 1.6 wt% NiO, and the balance support. Based on the total weight of the support, the phosphorus content (calculated as P2O5) is 1.5 wt%, and the halogen content (calculated as fluorine) is 1.0 wt%.

[0100] The alumina was prepared as follows: 2 L of aluminum sulfate solution with an Al2O3 concentration of 50 g / L was prepared, and 5 mL of concentrated phosphoric acid (85% by weight) was added to obtain a phosphorus-containing aluminum sulfate solution. The aluminum sulfate solution and an 8% ammonia solution were added concurrently to a 5 L reaction vessel to allow precipitation. The precipitate was then filtered (XRD characterization showed the hydrated alumina precipitate to be amorphous). The reaction temperature was 40 °C, and the flow rate of the ammonia solution was controlled to maintain the pH of the reaction system at 5.5. In a 5-liter reaction vessel, filter cake, deionized water, and ammonia were mixed and slurried. The amount of ammonia was adjusted to a pH of 8.0. The slurry was aged at 65°C for 60 minutes and then filtered. The filter cake was washed twice with deionized water and dried at 120°C for 24 hours to obtain hydrated alumina P3. P3 was calcined at 600°C for 4 hours to obtain alumina A3. XRD characterization showed that P3 had a boehmite-like structure and A3 had a γ-alumina structure. 1000g of the prepared hydrated alumina P3 was weighed and added to 1440ml of an aqueous solution containing 10ml of nitric acid (from Tianjin Chemical Reagent Factory No. 3) and 9.8g of ammonium fluoride. The solution was extruded into a butterfly-shaped strip with an outer diameter of φ1.4mm on a twin-screw extruder. The wet strip was dried at 120°C for 4 hours to obtain a molded product. This molded product was calcined at 600°C for 3 hours to obtain carrier Z3.

[0101] Take 200 g of support Z3, impregnate it with 220 mL of a mixed solution of ammonium heptamolybdate and nickel nitrate containing 80 g / L MoO3 and 16 g / L NiO for 1 hour, dry it at 120 °C for 4 hours, and calcine it at 400 °C for 3 hours to obtain catalyst C.

[0102] Table 3 Composition of catalysts A, B, and C

[0103]

[0104] Along the flow direction of distillate oil or heavy lubricating oil base oil, the second hydrogenation catalyst sequentially includes hydrogenation catalyst Ib, hydrogenation catalyst Ia and catalyst II, and the composition of the catalyst is shown in Table 4.

[0105] The hydrogenation catalyst Ia contains 2.4 wt% NiO, 2.1 wt% MoO3, 21 wt% WO3, 0.8 wt% P2O5 and 73.7 wt% silica-alumina support.

[0106] The solution was prepared by dissolving 3127g of Al2(SO4)3·18H2O (analytical grade, [Al2(SO4)3·18H2O] content ≥99 wt%, water-insoluble matter ≤0.02 wt%, chloride (Cl) ≤0.002 wt%, iron (Fe) ≤0.003 wt%, the same below) and 845g of 98% sulfuric acid (concentration 98 wt%, analytical grade, the same below) in 4968g of deionized water to prepare solution I (pH value 0.34, Al2O3 content 85 g / L). 2070g of sodium silicate solution (analytical grade, molecular formula: Na2SiO3·9H2O, content (as Na2O): 19.3-22.8 wt%, iron ≤0.02 wt%, heavy metals (as Pb) ≤0.001 wt%, the same below) was diluted with water to prepare solution II (containing 40 g / L SiO2, pH value 13.58). Under vigorous stirring, solution II and 1.75g ​​of ferrous sulfate (analytical grade, Beijing Yili Fine Chemicals Co., Ltd., the same below) were added to solution I to prepare a transparent silicon-aluminum mixed solution III. The pH of silicon-aluminum mixed solution III was 3.1, and the SiO2 / Al2O3 mass ratio was 3.0. Dilute ammonia water (containing 5 wt% NH3) was mixed with the above silicon-aluminum solution III at a stirring speed of 3000 RPM, wherein the ammonia water was added at a rate that adjusted the pH of the mixture to within the range of 8.0 ± 0.3.

[0107] After the ammonia water was added, the resulting product was stirred at 55-60℃ for 5 hours, filtered, and the resulting filter cake was mixed with hot deionized water, slurried, and filtered. This step was repeated 4 times. The filter cake was dried at 120℃ overnight to obtain the precursor SAS-1 of the silicon-aluminum composite material carrier. Based on the weight of the added ferrous sulfate and the obtained precursor SAS-1 of the silicon-aluminum composite material carrier, the iron content in the precursor of the silicon-aluminum composite material carrier, calculated as Fe2O3, was 0.09% by weight.

[0108] 1000 grams of the precursor of the above-mentioned silicon-aluminum composite material carrier SAS-1 was extruded into strips to obtain clover-shaped strips with a diameter of 1.3 mm. The wet clover-shaped strips were then dried at 120°C for 4 hours and then calcined in a tube furnace at 600°C for 4 hours with air to obtain catalyst carrier strips.

[0109] 3.12 g of concentrated phosphoric acid (85% by weight, analytical grade, Beijing Chemical Plant, hereinafter the same) and 40 mL of deionized water were heated to 75 °C, then mixed with 2.76 g of basic nickel carbonate (industrial grade, from Changling Catalyst Plant, hereinafter the same) and 5.73 g of molybdenum trioxide (industrial grade, from Changling Catalyst Plant, hereinafter the same), and the mixture was heated and stirred until dissolved. The solution was clear and transparent, and cooled to room temperature to obtain solution I. 62.96 g of ammonium metatungstate (industrial grade, Sichuan Zigong Hard Alloy Plant, hereinafter the same) and 20.68 g of nickel nitrate (analytical grade, Beijing Shuanghuan Chemical Reagent Plant, hereinafter the same) were added to 80 mL of deionized water and stirred until dissolved to obtain solution II. Solutions I and II were mixed at room temperature and adjusted to 160 mL with deionized water to obtain solution III. 200 g of the above support strip was impregnated with solution III for 1 hour, then removed and dried at 120 °C for 4 hours, and then calcined in air at 450 °C for 4 hours to obtain hydrogenation catalyst I.

[0110] The hydrogenation catalyst Ib uses commercially available RG-1 catalyst, produced by Changling Catalyst Factory, containing 1.0 wt% NiO, 5.5 wt% MoO3, and the remainder alumina support.

[0111] Catalyst II contains 3.2 wt% NiO, 1.1 wt% CoO, 15.1 wt% WO3, 13.6 wt% MoO3 and 5.0 wt% P2O5 and the balance alumina support.

[0112] The catalyst was prepared as follows: 200.0 g of industrial alumina support was weighed and impregnated with 168.0 mL of an aqueous solution containing 59.1 g of ammonium metatungstate, 51.9 g of ammonium paramolybdate, and 3.4 g of phosphoric acid for 1 hour. It was then dried at 120°C for 6 hours and calcined at 330°C for 6 hours to obtain catalyst intermediate Z1. Half the weight of intermediate Z1 was sulfided with H2 containing 10.0% H2S by volume at 380°C and atmospheric pressure for 5 hours to obtain catalyst intermediate Z2. Intermediate Z2 was further impregnated with 53.0 mL of an aqueous solution containing 10.8 g of basic nickel carbonate, 3.4 g of basic cobalt carbonate, and 10.1 g of phosphoric acid for 1 hour, and then dried at 100°C under nitrogen purging for 8 hours to obtain catalyst II.

[0113] Table 4 Properties of hydrogenation catalysts Ia, II, and Ib

[0114]

[0115] Examples 2-7

[0116] Waste lubricating oil was treated using the same method as in Example 1, except that the reaction conditions were different, as shown in Table 5. The base oil yield is shown in Table 6.

[0117] Comparative Example 1

[0118] Waste lubricating oil was processed using a conventional vacuum fractionation-hydrorefining process. The properties of the base oil intermediates obtained from vacuum fractionation are shown in Table 7. The yield of the base oil intermediates after vacuum fractionation was 82%. After hydrorefining, the yield of the base oil was approximately 93.9%. Specific process parameters are shown in Table 8.

[0119] Table 5

[0120]

[0121]

[0122]

[0123] In Table 5, catalyst dosage (μg / g) refers to the amount of carbon-supported catalyst, calculated as metal element, relative to 1g of the waste lubricating oil. Accelerator dosage (μg / g) refers to the amount of accelerator relative to 1g of the waste lubricating oil.

[0124] In the solid-liquid separation step, the total liquid yield = distillate oil yield + heavy lubricating oil base oil yield.

[0125] Catalyst I includes hydrogenation catalyst Ia and hydrogenation catalyst Ib. The reaction conditions for hydrogenation catalyst Ia and hydrogenation catalyst Ib are the same, as shown in the table for catalyst I.

[0126] Table 6 Base Oil Yield

[0127]

[0128]

[0129] In Table 6, the total yield = yield of 150N base oil fraction treated with medium-pressure hydrotreating × yield of 150N base oil treated with high-pressure hydrotreating + yield of 120BS base oil fraction treated with medium-pressure hydrotreating × yield of 120BS base oil treated with high-pressure hydrotreating

[0130] The data corresponding to the hydrotreated liquid yield in Comparative Example 1 is actually the distillation pretreated liquid yield, and the data corresponding to the 150N base oil fraction yield in medium-pressure hydrotreated oil is actually the distillation pretreated lubricating oil base oil yield.

[0131] Table 7

[0132] nature Chlorine content, mg / kg 70 Sulfur content, mg / kg 674 Total acid value, mgKOH / g 0.24 Fe, mg / kg <1 Ni, mg / kg <1 V, mg / kg <1 Na, mg / kg <1 Ca, mg / kg <1 Si, mg / kg 61 Nitrogen content, mg / kg 245 <![CDATA[Viscosity at 40℃, mm 2 / s]]> 31.71 <![CDATA[Viscosity at 100°C, mm 2 / s]]> 5.535 <![CDATA[Density at 20°C, kg / m 3 > 854.5 Refractive index at 20℃ 1.4718 Residual char, % (w) <0.05 Total aromatics, % (w) 7.7

[0133] Table 8

[0134]

[0135]

[0136] As can be seen from the above, the method disclosed herein can effectively remove metal and non-metal heteroatoms from waste oil, produce high-quality lubricating oil base oil and bright oil, and has a high overall yield.

[0137] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0138] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0139] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for hydroregeneration of waste lubricating oil, the method comprising: S1. Waste lubricating oil, carbon-supported catalyst and accelerator are contacted in a slurry bed for hydrogenation pretreatment to obtain a hydrogenated mixture; S2. Perform solid-liquid separation on the hydrogenated mixture to obtain waste agent and lubricating oil base oil fraction; S3. In a medium-pressure fixed-bed hydrogenation unit, the lubricating oil base oil fraction is brought into contact with the first hydrogenation catalyst to carry out a medium-pressure hydrogenation reaction to obtain a medium-pressure hydrogenation product. S4. The medium-pressure hydrogenation product is fractionated to obtain gas, distillate oil, light lubricating oil fraction and heavy lubricating oil fraction; S5. In the high-pressure fixed-bed hydrogenation unit, the light lubricating oil fraction and the heavy lubricating oil fraction are respectively brought into contact with the second hydrogenation catalyst to carry out high-pressure hydrogenation reaction.

2. The method according to claim 1, wherein, In step S1, the conditions for the hydrogen pretreatment include: a reaction temperature of 300-480℃; a reaction pressure of 2-25 MPa; and a liquid hourly space velocity of 0.2-4 h⁻¹. -1 The volume ratio of hydrogen to the waste lubricating oil is 100-3000 Nm³. 3 / m 3 .

3. The method according to claim 1, wherein, In step S1, the carbon-supported catalyst comprises a carbon-based support and an active metal component; based on the total weight of the carbon-supported catalyst and calculated by metal element, the content of the active metal component is 1-50% by weight. The carbon-based carrier comprises carbon-containing materials with a carbon content greater than 80% by weight; the metal elements in the active metal component include one or more of Fe, Co, Mo, W and Ni.

4. The method according to claim 1, wherein, In step S1, the amount of the carbon-supported catalyst, calculated as metal element, is 20-10000 μg relative to 1g of the waste lubricating oil, preferably 50-5000 μg, and more preferably 100-3000 μg.

5. The method according to claim 1, wherein, In step S1, the accelerator contains a sulfur-containing substance; preferably, the sulfur-containing substance is selected from one or more of carbon disulfide, sulfur, dimethyl disulfide and di-tert-butyl polysulfide. The amount of the accelerator is 10-20000 μg relative to 1g of the waste lubricating oil, preferably 50-6000 μg.

6. The method according to claim 1, wherein, In step S3, the conditions for the medium-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-20 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm. 3 / m 3 The reaction temperature is 260-380℃, and the volume hourly space velocity is 0.2-5h. -1 ; Preferably, the hydrogen partial pressure is 5-12 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature is 280-360℃, and the volume hourly space velocity is 0.3-3h. -1 .

7. The method according to claim 1, wherein, In step S3, along the flow direction of the lubricating oil base oil fraction, the first hydrogenation catalyst includes catalyst A, catalyst B and catalyst C arranged sequentially; by volume and based on the total volume of the first hydrogenation catalyst, the content of catalyst A in the first hydrogenation catalyst is 5-20%, the content of catalyst B is 10-50%, and the content of catalyst C is 30-85%. The catalyst A contains a first hydrogenation active metal and a first support; the first hydrogenation active metal includes a Group VIB metal and optionally a Group VIII metal, and the first support is selected from alumina and / or silica; the first support contains phosphorus, and the phosphorus content, based on the total weight of the first support and calculated as P2O5, is 0.1-8.0% by weight; based on the total weight of the catalyst A and calculated as oxides, the content of the Group VIB metal is greater than 0 and less than 10% by weight, and the content of the Group VIII metal is 0.2-5% by weight; The catalyst B contains a second hydrogenation active metal and a second support; the second hydrogenation active metal includes a Group VIB metal and optionally a Group VB metal, and the second support is selected from alumina and / or silicon oxide; the second support contains phosphorus and halogens, with the phosphorus content (based on the total weight of the second support, calculated as P2O5) being 0.1-8.0% by weight and the halogen content (based on the element) being 0.1-6% by weight; based on the total weight of the catalyst B and calculated as oxides, the content of the Group VIB metal is greater than 0.2% and less than 12% by weight, and the content of the Group VB metal is 0-12% by weight; The catalyst C contains a third hydrogenation active metal and a third support; the third hydrogenation active metal includes Group VIB metals and optionally Group VIII metals, and the third support is selected from alumina and / or silicon oxide; the third support contains phosphorus and halogens, with the phosphorus content (based on the total weight of the third support, calculated as P2O5) being 0.1-8.0% by weight and the halogen content (based on the elemental content) being 0.1-6% by weight; based on the total weight of the catalyst C and calculated as oxides, the content of the Group VIB metal is 0.2-10% by weight and the content of the Group VIII metal is less than 5% by weight; Preferably, the volume ratio of catalyst A, catalyst B and catalyst C is 1:(1-10):(1.5-17), more preferably 1:(2-5):(3-15).

8. The method according to claim 1, wherein, In step S4, the fractionation conditions include: a pressure of -90 kPa to -99 kPa and a bottom temperature of 320-370 °C. The cutoff point between the distillate oil and the light lubricating oil fraction is 300-320℃; the cutoff point between the light lubricating oil fraction and the heavy lubricating oil fraction is 500-540℃.

9. The method according to claim 1, wherein, In step S5, along the flow direction of the light lubricating oil fraction and the heavy lubricating oil fraction, the second hydrogenation catalyst includes catalyst I and catalyst II in sequence; The catalyst I comprises a hydrogenation catalyst Ia, which contains a first promoter, a fourth hydrogenation active metal component, and a fourth support; the first promoter comprises one or more of fluorine, boron, and phosphorus; the metal element in the first hydrogenation active metal component comprises one or more of Co, Mo, Ni, and W; the fourth support is selected from alumina and / or silicon oxide; based on the dry weight of the hydrogenation catalyst Ia, the content of the fourth hydrogenation active metal component, calculated as metal oxide, is 22-32% by weight, and the content of the first promoter is 3-10% by weight; Preferably, the catalyst I further includes a hydrogenation catalyst Ib disposed upstream of the hydrogenation catalyst Ia; the hydrogenation catalyst Ib contains a fifth hydrogenation active metal component and a fifth support, and the content of the fifth hydrogenation active metal component is 2-15% by weight based on the dry weight of the hydrogenation catalyst Ib; the fifth hydrogenation active metal component is selected from one or more of Co, Mo, Ni and W; the fifth support is selected from alumina and / or silicon oxide; Preferably, the volume ratio of the hydrogenation catalyst Ia to the hydrogenation catalyst Ib is (3-10):

1.

10. The method according to claim 9, wherein, In step S5, the second hydrogenation catalyst further includes catalyst II disposed downstream of catalyst I; Catalyst II comprises a second promoter, a sixth hydrogenation active metal component, and a sixth support; the second promoter contains boron and / or phosphorus, and the content of the sixth hydrogenation active metal component, calculated as metal oxide, is 22-36% by weight based on the dry weight of catalyst II; the content of the second promoter is 2-8% by weight; the sixth hydrogenation active metal component is selected from one or more of Co, Mo, Ni, and W; the sixth support is selected from alumina and / or silicon oxide; the hydrogenation catalyst II is a fluorine-free hydrogenation catalyst; the content of the sixth hydrogenation active metal component of the hydrogenation catalyst II is greater than or equal to the content of the fourth hydrogenation active metal component of the hydrogenation catalyst Ia; Preferably, the volume ratio of catalyst I to catalyst II is (30:70)-(60:40).

11. The method according to claim 9, wherein, In step S5, the conditions for the high-pressure hydrogenation reaction include: a hydrogen partial pressure of 3-25 MPa and a hydrogen-to-oil volume ratio of 200-3000 Nm³. 3 / m 3 The reaction temperature of catalyst I is 260-420℃, and the volume hourly space velocity is 0.2-3h. -1 The reaction temperature of catalyst II is 240-380℃, and the volume hourly space velocity is 0.2-3h. -1 ; Preferably, the hydrogen partial pressure is 5-20 MPa, and the hydrogen-to-oil volume ratio is 300-1800 Nm. 3 / m 3 The reaction temperature of catalyst I is 280-360℃, and the volume hourly space velocity is 0.3-2h. -1 The reaction temperature of catalyst II is 260-340℃, and the volume hourly space velocity is 0.3-2h. -1 .

12. A system for hydrogenating and regenerating waste lubricating oil using any one of claims 1-11, the system comprising: Slurry bed, solid-liquid separation unit, medium-pressure fixed bed hydrogenation unit, fractionation tower and high-pressure fixed bed hydrogenation unit; The product outlet of the slurry bed is fluidly connected to the inlet of the solid-liquid separation device, the liquid outlet of the solid-liquid separation device is fluidly connected to the inlet of the medium-pressure fixed-bed hydrogenation device, the outlet of the medium-pressure fixed-bed hydrogenation device is fluidly connected to the inlet of the fractionation tower, and the outlets of the light lubricating oil fraction and the heavy lubricating oil fraction of the fractionation tower are each independently fluidly connected to the inlet of the high-pressure fixed-bed hydrogenation device.

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