Upgrading of used lubricating oil to group ii / iii base stock at high yield

Abstract

Methods relate to processing a used lubricating oil, to form high quality Group II base stocks and Group III base stocks from pre-processed used lubricating oil.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of U.S. Provisional Patent Application No. 63 / 684,219, filed Aug. 16, 2024, which is incorporated by reference in its entirety.FIELD

[0002] This disclosure relates to base stocks, and more particularly, example embodiments relate to base stocks made from used lubricating oils, blends of base stocks, formulated lubricant compositions containing the base stocks, and uses of base stocks.BACKGROUND

[0003] Base stocks are the major constituent in finished lubricants and contribute significantly to their properties. For example, engine oils are finished crankcase lubricants intended for use in automobile engines and diesel engines and contain two general components, namely, a base stock (one base stock or a blend of base stocks) and additives. In general, a few lubricating base stocks are used to manufacture a variety of engine oils by varying the mixtures of individual lubricating base stocks and individual additives. Base stocks are also used for other purposes and industries such as processing oils for manufacturing and industrial oils in the marine and paper industries.

[0004] According to the American Petroleum Institute (API) classifications, base stocks are categorized in five groups based on their saturated hydrocarbon content, sulfur level, and viscosity index (Table 1). Lubricant base stocks are typically produced on a large scale from petroleum sources. Group I, II, and III base stocks are all derived from crude oil via extensive processing, such as solvent extraction, solvent or catalytic dewaxing, and hydroisomerization. Group III base stocks can also be produced from synthetic hydrocarbon liquids obtained from natural gas, coal or other fossil resources, Group IV base stocks are polyalphaolefins (PAOs), and are produced by oligomerization of alpha olefins, such as 1-decene. Group V base stocks include all base stocks that do not belong to Groups I-IV, such as naphthenics, polyalkylene glycols (PAG), and esters.TABLE 1APIGroupGroupGroupclassificationIIIIIIGroup IVGroup V% Saturates<90≥90≥90PolyalphaolefinsAll others% Sulfur>0.03≤0.03≤0.03(PAOs)notViscosity80-12080-120120belongingIndex (VI)to group I-IV

[0005] Base stocks are the key building blocks of lubricants and greases. A base stock is typically defined as a single lubricant component produced by a single manufacturer. The terms base stocks and base oils are often used interchangeably, but there are differences. A base stock is a single product, usually defined by its viscosity grade. A mixture of one or more base stocks in a finished lubricant is a base oil. A base oil is always defined in the context in the formulated lubricant. Base oil properties can vary depending on their API group. Base stocks are generally produced from the higher boiling fractions recovered from a vacuum distillation operation. They may be prepared from either petroleum-derived or from syncrude-derived feed stocks or from synthesis of lower molecular weight molecules. Base stocks are blended to form a base oil to which additives are added to form the finished lubricant. Additives are chemicals which are added to base stock to improve certain properties in the finished lubricant so that it meets the minimum performance standards for the grade of the finished lubricant. For example, additives added to engine oils may be used to improve oxidation stability of the lubricant, increase its viscosity, raise the viscosity index, and control deposits.

[0006] Lubricating oils are utilized in machinery for various purposes such as to lubricate surfaces, cool components, provide anti-corrosion and other modifiers to surfaces, and catch contaminants from combustion. Lubricating oils are utilized in a variety of applications including, but not limited to, vehicle engines, industrial gearboxes and pumps, compressors, and hydraulic units. When the lubricating oil is circulated throughout the machinery, the lubricating oil becomes contaminated with metal shavings and debris from the machinery as well as chemical impurities such as water, fuel, and combustion products.

[0007] Lubricating oils are changed when the oil no longer meets the specification requirements or at regular intervals. The lubricating oil becomes “used up” when the additive package in the lubricating oil is depleted and the oil becomes contaminated. However, the base oils which make up the bulk volume of the lubricating oils are not used up under normal engine conditions and thus can be recycled to form new base oils. Re-refiners may utilize the used lubricating oil in a reclamation process to recover the base stock fractions in the used lubricating oil. The reclamation process typically includes multiple cleaning and stripping steps to remove physical and chemical contaminants from the used lubricating oil followed by liquid-liquid extraction processes to recover a Group I base stock and low pressure hydrotreating to recover group II base stocks.SUMMARY OF THE INVENTION

[0008] The invention includes methods for producing group II and / or group III base stocks as blended or neat at high yields by tailoring the hydroprocessing steps and conditions from used oils such as pre-processed used lubricating oils. According to an embodiment, the invention includes a method for producing base stock from pre-processed used lubricating oil comprising: introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section; contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section; contacting an effluent from the demetallization section with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating the effluent to form a hydrotreated oil; introducing the hydrotreated oil into a first separation unit and separating a light end fraction from the hydrotreated oil; introducing the hydrotreated oil into a hydrofinishing unit comprising a hydrofinishing section; contacting the hydrotreated oil with a hydrofinishing catalyst in the hydrofinishing section to hydrofinish at least a portion of the hydrotreated oil to form a hydrofinished oil; and introducing the hydrofinished oil into a second separation unit and separating a base stock fraction from the hydrofinished oil.

[0009] According to a further embodiment, the invention includes a method for producing base stock from pre-processed used oils comprising: introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section; contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section and demetallizing at least a portion of the pre-processed used lubricating oil; contacting the pre-processed used lubricating oil with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating at least a portion of the pre-processed used lubricating oil to form a hydrotreated oil; introducing the hydrotreated oil into a hydrodewaxing unit comprising a hydrodewaxing section and contacting the hydrotreated oil with a dewaxing catalyst in the hydrodewaxing section to form a dewaxed oil; introducing the dewaxed oil into a hydrofinishing unit comprising a hydrofinishing section and hydrofinishing the dewaxed oil to form a hydrofinished lubricant boiling range product; and introducing the hydrofinished lubricant boiling range product into a separation unit and separating a Group II / III base stock fraction.

[0010] These and other features and attributes of the disclosed methods for producing base stocks from pre-processed used lubricating oils, base stocks made from used lubricating oils, blends of base stocks, formulated lubricant compositions containing the base stocks, and uses of base stocks of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:

[0012] FIG. 1 is a schematic illustration of a process for processing used lubricating oil in accordance with certain embodiments of the present disclosure.

[0013] FIG. 2 is a schematic illustration of a process for processing used lubricating oil in accordance with certain embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] Disclosed herein are methods of processing a used lubricating oil, and more particularly, example embodiments relate to methods to increase the production of high quality Group II base stocks and Group III base stocks from used lubricating oil. The example embodiments disclosed herein have several advantages over previously disclosed methods of processing a used lubricating oil, only some of which may be allude to herein. The Group II and Group III base stocks produced according to the example embodiments disclosed herein have no blending debit when combined with Group II and Group III base stocks produced by conventional fractionation distillation and processing of crude oil. The Group II and Group III base stocks produced according to the example embodiments disclosed herein have viscosity index (VI), cold crank simulator (CCS), and other relevant physical properties within range of conventionally produced Group II and Group III base stocks, thereby allowing the Group II and Group III base stocks produced from the used lubricating oil to be integrated into existing blending schemes.Feedstocks

[0015] In various embodiments, the used lubricating oil employed in the present process may be collected from various sources including industrial, commercial, and / or residential sources and may include mixtures of used lubricating oils from these sources. In embodiments, the used lubricating oil has been used in an engine, transmission, or other lubricating application. The used lubricating oil may include, without limitation, oils such as transmission oil, gear oil, engine oil, crankcase oil, compressor oil, pump oil, hydraulic oil, or any combination thereof. The used lubricating oil in some examples includes a mixture of petroleum mineral oils derived from the processing of petroleum crude and / or oils, used lubricating oil containing base stocks derived from Fischer Tropsch waxes, used lubricating oil containing base stocks derived from polyolefin processing, used mineral oils, and used synthetic base oils. It should be noted that a polyalphaolefin or unsaturated PAO of the present disclosure can be introduced into a stream during the re-refining process, for example before or after distillation / hydrogenation. As used herein, “polyalpha-olefin(s)” (“PAO(s)”) includes any oligomer(s) and polymer(s) of one or more alpha-olefin monomer(s). PAOs are oligomeric or polymeric molecules produced from the polymerization reactions of alpha-olefin monomer molecules in the presence of a catalyst system, optionally further hydrogenated to remove residual carbon-carbon double bonds therein. Thus, the PAO can be a dimer, a trimer, a tetramer, or any other oligomer or polymer comprising two or more structure units derived from one or more alpha-olefin monomer(s). In embodiments, the used lubricating oil includes additive packages including but not limited to antiwear additives, detergents, dispersants, viscosity modifiers, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, other viscosity modifiers, fluid-loss additives, seal compatibility agents, lubricity agents, anti-staining agents, chromophoric agents, anti-foam agents, antioxidants, anti-rust additives, anti-wear additives, pour point depressant, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. In embodiments the used lubricating oil includes water and insoluble particulates such as carbon, metal shavings, and combustion deposits.

[0016] In embodiments, the used lubricating oil is subjected to a series of pre-processing steps whereby the used lubricating oil is cleaned of at least a portion of the contaminants such as additives, water, and insoluble particles. For example, water may be removed in a dehydration unit whereby water may be stripped, decanted, or otherwise removed from the bulk used lubricating oil. In embodiments, a filtration unit is utilized to filter solid particulates from the used lubricating oil. In embodiments, the used lubricating oil may be subjected to vacuum distillation, chemical addition, or other separation steps.

[0017] In embodiments, pre-processed used lubricating oil is utilized as a feedstock in the disclosed methods of producing base stocks. The feedstock for the process can have any viscosity. In various embodiments, the pre-processed used lubricating oil has a kinematic viscosity at 100° C. (KV100) of at least 3 centistokes (cSt). In various embodiments, the feedstock has a KV100 at a point in a range of 3 cSt to 8 cSt. Alternatively, the feedstock has a KV100 at a point in a range of 3 cSt to 5.5 cSt, at a point in a range of 5.5 cSt to 8 cSt, at a point in a range of 4 cSt to 6 cSt or any ranges therebetween. Although the feedstock can have any viscosity index (VI), in various embodiments the used lubricating oil has a VI of at least 90, preferably in a range of 100-120. In some embodiments, the feedstock has a VI at a point in a range of from 90 to 130. Alternatively, the feedstock has a VI at a point in a range of from 90 to 115, at a point in a range of from 115 to 130, or any ranges therebetween. In embodiments, the pre-processed used lubricating oil has an initial boiling point (T5) at a point in a range of 330° C. to 380° C. and a final boiling point (T95) in a range of 450° C. to 560° C. In further embodiments the pre-processed used lubricating oil contains low levels of contaminants, including spent additives and wear materials, such as about 0.00 wt. %, 0.01 to 5.0 wt. %, 0.05 to 2.0 wt. % contaminant loading, or any ranges there-between.

[0018] In some embodiments, the pre-processed used lubricating oil contains greater than 500 wppm sulfur as determined by ASTM 2622. When the pre-processed used lubricating oil contains greater than 500 wppm sulfur, the oil is considered a “sour” feed. In embodiments, the pre-processed used lubricating oil contains sulfur in an amount of 500 wppm to 5,000 wppm sulfur. In example embodiments including a hydrotreatment process and / or a sour hydrocracking process, the feed can have a sulfur content of 500 wppm to 1000 wppm, or 1000 wppm to 2500 wppm, 2500 wppm to 5000 wppm, or any ranges therebetween. Additionally or alternately, the nitrogen content may be in a range of 0 wppm to 1000 wppm, 50 wppm to 500, 500 to 1000 wppm, or any ranges therebetween. In some embodiments, the feed can correspond to a “sweet” feed, so that the sulfur content of the feed is about 10 wppm to about 200 wppm and / or the nitrogen content is about 1 wppm to about 20 wppm.

[0019] In embodiments, the pre-processed used lubricating oil contains halides in an amount of 0 wppm to 100 wppm, such as from 0 wppm to 25 wppm, 25 wppm to 50 wppm, 50 wppm to 100 wppm, or any ranges therebetween. In further embodiments, the pre-processed used lubricating oil contains a total content of metal contaminants by D5185 such as phosphorus, calcium, zinc and silicon is typically between from 0 wppm to 200 wppm, such as from 0 wppm to 25 wppm, 25 wppm to 100 wppm, 100 wppm to 200 wppm, or any ranges therebetween.Process for Producing Base Stocks

[0020] FIG. 1 is a block flow diagram of a process 100 to produce base stocks in accordance with some embodiments of the present disclosure. As discussed above, pre-processed used lubricating oil can come from many sources. As shown in FIG. 1, a first pre-processed used lubricating oil 102 and a second pre-processed used lubricating oil 104 are introduced into storage tank 106 where each of the pre-processed used lubricating oils are sourced from different places. From storage tank 106, feed stream 108 is introduced into furnace 110 and heated before being introduced into hydrotreatment unit 114 as heated feed stream 112. In embodiments, process 100 utilizes only pre-processed used lubricating oil as a feed whereby feed stream 108 corresponds to 100 wt. % pre-processed used lubricating oils. Further in embodiments, feed stream 108 corresponds to a combined feed stream containing 500 wppm or more sulfur.

[0021] Hydrotreatment unit 114 includes at least two sections, a first section including a demetallization catalyst, and a second section including a hydrotreatment catalyst. In hydrotreatment unit 114 the pre-processed used lubricating oil is mixed with hydrogen and contacted with the demetallization catalyst at conditions suitable to remove contaminants from the oil. Without being limited by theory, it is believed that the hydrogen facilitates the reaction by reducing the metal components present in the oil to the corresponding metallic form and thereafter the reduced metals are then adsorbed onto the demetallization catalyst and removed from the oil. In embodiments, the demetallization catalyst includes an active metal such as molybdenum and / or cobalt supported on alumina.

[0022] From the demetallization section, the effluent having a reduced metal content as compared to the feed, is passed to the hydrotreatment section. The effluent can include sulfur in an amount of greater than 500 wppm such that the hydrotreatment section corresponds to sour stage hydrotreatment. Hydrotreatment reduces the sulfur, nitrogen, and aromatic content of the effluent oil.

[0023] In embodiments, the hydrotreatment unit 114 is operated at a temperature at a point in a range of 300° C. to 450° C. Alternatively, the hydrotreatment unit is operated at a temperature at a point in a range of 300° C. to 350° C., at a point in a range of 350° C. to 375° C., at a point in a range of 375° C. to 400° C., at a point in a range of 400° C. to 450° C., or any ranges therebetween.

[0024] In embodiments, the hydrotreatment unit 114 is operated at hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 3000 psig (20.68 MPa). Alternatively, the hydrotreatment unit 114 is operated at a hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 1000 psig (6.89 MPa), a hydrogen partial pressure at a point in a range of 1000 psig (6.89 MPa) to 2000 psig (13.78 MPa), a hydrogen partial pressure at a point in a range of 2000 psig (13.78 MPa) to 3000 psig (20.68 MPa), or any ranges therebetween.

[0025] In embodiments, the hydrotreatment unit 114 is operated at a Liquid Hourly Space Velocity (LHSV) at a point in a range of 0.1-5.0 h−1. Alternatively, at a LHSV at point in a range of 0.1-1.0 h−1, at a LHSV at a point in a range of 2.0-3.0 h−1, at a LHSV at a point in a range of 3.0-5.0 h−1, or any ranges therebetween in the hydrotreatment section.

[0026] In embodiments, the hydrotreatment unit 114 is operated at a total treat gas ratio, i.e. the treat gas at reactor inlet and all inter-bed gas quenches, at a point in a range of 1000 scf / B to 6000 scf / B. Alternatively, the hydrotreatment section is operated at a total treat gas ratio at a point in a range of 1000 scf / B to 2000 scf / B, at a point in a range of 2000 scf / B to 4000 scf / B, at a point in a range of 4000 scf / B to 6000 scf / B, or any ranges therebetween.

[0027] In embodiments, hydrotreating section includes a hydrotreating catalyst such as those catalysts containing Group VIB metals, such as molybdenum and / or tungsten, and non-noble Group VIII metals, such as, iron, cobalt and nickel and mixtures thereof. These metals or mixtures of metals are typically present as oxides or sulfides on refractory metal oxide supports. Alternatively, the hydrotreating catalyst includes a bulk metal catalyst, or a combination of stacked beds of supported and bulk metal catalyst.

[0028] Hydrotreatment is carried out in the presence of hydrogen. A hydrogen stream is, therefore, fed or injected into a vessel or reaction zone or hydrotreating section in which the hydrotreating catalyst is located. Hydrogen, which is contained in a hydrogen “treat gas,” is provided to the reaction zone. Treat gas can be either pure hydrogen or a hydrogen-containing gas, which is a gas stream containing hydrogen in an amount that is sufficient for the intended reaction(s), optionally including one or more other gasses (e.g., and light hydrocarbons such as methane), and which will not adversely interfere with or affect either the reactions or the products. The effluent from the demetallization section is contacted with the hydrogen in the presence of the hydrotreating catalyst to reduce amount the sulfur, nitrogen, and / or aromatic.

[0029] The hydrotreated oil is withdrawn from hydrotreatment unit 114 as stream 116 which is then introduced into a light end separation unit 118. Light end separation unit 118 is configured to separate the hydrotreated oil from a light ends fraction such as hydrogen sulfide, ammonia, water, and light hydrocarbons (including hydrocarbons with boiling points less than 370° C.) generated in hydrotreatment unit 114. Light ends are withdrawn from separation unit 118 as light ends stream 136. In embodiments, light end separation unit 118 includes equipment such as strippers, distillation columns, fractionators, or any other equipment suitable for separating the hydrotreated oil from the light ends.

[0030] The oil having the light ends removed is withdrawn from light end separation unit 118 as stream 120 and introduced into hydrofinishing unit 122. In embodiments, the hydrofinishing unit also performs hydrogenation of aromatics. In embodiments, hydrofinishing unit 122 includes a hydrofinishing catalyst that includes Pt, Pd, or a combination thereof on a support such as alumina or titania. In embodiments the hydrofinishing catalyst includes hydrotreating catalysts with Pt or Pd supported on alumina, amorphous alumina / silica, and / or zeolite. In embodiments, the hydrofinishing catalyst can include from 0.1 wt. % to 2.0 wt. % of hydrogenation metal relative to the weight of the support. Due to the low acidity support, this type of catalyst causes little or no cracking of feed while being effective for reduction of single ring and multi-ring aromatics.

[0031] In some embodiments, an aromatic saturation process can optionally include multiple beds and / or sections of hydrofinishing catalyst. The multiple beds or sections can be organized in a single reactor or in a plurality of reactors. Optionally, the hydrofinishing reactor has the inter-bed quench to operate in a descending temperature profile to maximize the saturation of single ring and multi-ring aromatics. Optionally, the hydrofinishing reactor has the inter-bed quench to operate in a descending temperature profile to maximize the saturation of single ring and multi-ring aromatics.

[0032] In embodiments, hydrofinishing unit 122 is operated at hydrofinishing conditions. In embodiments, the hydrofinishing section is operated at a temperature at a point in a range of 200° C. to 280° C. Alternatively, the hydrofinishing unit 122 is operated at a temperature at a point in a range of 200° C. to 230° C., a temperature at a point in a range of 230° C. to 250° C., a temperature at a point in a range of 250° C. to 280° C., or any ranges therebetween.

[0033] In embodiments, hydrofinishing unit 122 is operated at is operated at hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 3000 psig (20.68 MPa). Alternatively, the hydrofinishing unit 122 is operated at a hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 1000 psig (6.89 MPa), a hydrogen partial pressure at a point in a range of 1000 psig (6.89 MPa) to 2000 psig (13.78 MPa), a hydrogen partial pressure at a point in a range of 2000 psig (13.78 MPa) to 3000 psig (20.68 MPa), or any ranges therebetween.

[0034] In embodiments, hydrofinishing unit 122 is operated at a total treat gas ratio, i.e. the treat gas at reactor inlet and all inter-bed gas quenches, at a point in a range of 1000 scf / B to 5000 scf / B. Alternatively, the hydrotreatment section is operated at a total treat gas ratio at a point in a range of 1000 scf / B to 2000 scf / B, at a point in a range of 2000 scf / B to 4000 scf / B, at a point in a range of 4000 scf / B to 5000 scf / B, or any ranges therebetween.

[0035] In embodiments, hydrofinishing unit 122 is operated at an LHSV at a point in a range of 0.5-5.0 h−1 in the hydrofinishing section. Alternatively, the hydrofinishing unit is operated at an LHSV at a point in a range of 0.5-1.0 h−1, at a LHSV point in a range of 1.0-3.0 h−1, at a LHSV point in a range of 3.0-5.0 h−1, or any LHSV ranges therebetween in the hydrofinishing section.

[0036] After hydrofinishing, the aromatics content of the hydrofinished lubricant boiling range product (hydrofinished oil) can be in a range of 0.0 wt. % to 3.0% wt. %. In embodiments, the aromatics content is 1.5 wt. % or less, or 1.0 wt. % or less, or 0.5 wt. % or less, or 0.4 wt. % or less, or 0.3 wt. % or less, or 0.2 wt. % or less, or 0.1 wt. % or less. Additionally, or alternatively, the 3-ring aromatics content of the hydrofinished lubricant boiling range product can be at a point in a range of 0.000 wt. % to 0.100 wt. %. In embodiments, the 3-ring aromatics content is 0.050 wt. % or less, or 0.040 wt. % or less, or 0.035 wt. % or less, or 0.030 wt. % or less, or 0.025 wt. % or less, or 0.020 wt. % or less, or 0.015 wt. % or less, or 0.010 wt. % or less. In embodiments, the aromatics content is determined according to ASTM D-2007.

[0037] As used herein, the naphtha boiling range is defined as 50° F. (10° C., corresponding to the lowest boiling point of a pentane isomer) to 315° F. (157° C.). The jet boiling range is defined as 315° F. (157° C.) to 460° F. (238° C.). The diesel boiling range is defined as 460° F. (238° C.) to 650° F. (343° C.). The distillate fuel boiling range (jet plus diesel) is defined as 315° F. (157° C.) to 650° F. (343° C.). The fuels boiling range is defined as ˜10° C. to 343° C. The lubricant boiling range is defined as 650° F. (343° C.) to 1050° F. (566° C.). Optionally, when forming a lubricant boiling portion by fractionation after one or more stages of hydroprocessing (e.g., hydrotreating, hydrocracking, catalytic dewaxing, hydrofinishing), a lubricant boiling range portion can optionally correspond to a bottoms fraction, so that higher boiling range compounds may also be included in the lubricant boiling range portion. Compounds (C4−) with a boiling point below the naphtha boiling range can be referred to as light ends. It is noted that due to practical consideration during fractionation (or other boiling point-based separation) of hydrocarbon-like fractions, a fuel fraction formed according to the methods described herein may have T5 and T95 distillation points corresponding to the above values (or T10 and T90 distillation points), as opposed to having initial / final boiling points corresponding to the above values.

[0038] From hydrofinishing unit 122 the hydrofinished lubricant boiling range product is withdrawn as stream 124 and introduced into separation unit 126. The hydrofinished lubricant boiling range product corresponds to a Group II / III base stock. In embodiments, separation unit 126 is configured to separate the hydrofinished lubricant boiling range product from light ends such as fuel boiling point range hydrocarbons generated in hydrofinishing unit 122. The fuel boiling point range hydrocarbons are withdrawn as fuel stream 130. In embodiments, separation unit 126 includes equipment such as strippers, distillation columns, fractionators, or any other equipment suitable for separating hydrofinished lubricant boiling range product from the fuel range light ends. Fuel range light ends include gasoline range hydrocarbons with approximately 4-12 carbon atoms typically with a boiling range between 30° C. and 210° C. as well as diesel range hydrocarbons with approximately 12-20 carbon atoms with a boiling range between 170° C. and 360° C.

[0039] The hydrofinished lubricant boiling range product is withdrawn from separation unit 126 as product stream 128. In optional embodiments, product stream 128 is transferred to lubricant blending pool 134. Optionally, conventionally produced lubricant boiling range product produced from distillation and processing of crude can be directly blended with the product stream as shown in FIG. 1 by conventional lubricant boiling range product 132 being introduced into lubricant blending pool 134.

[0040] FIG. 2 is a block flow diagram of a process 200 to produce base stocks in accordance with some embodiments of the present disclosure. Process 200 is identical to process 100 with the addition of a dewaxing section 140.

[0041] From light end separation unit 118, stream 120 is withdrawn and introduced into dewaxing section 140. In embodiments, dewaxing section 140 includes one or more of catalytic dewaxing or hydrodewaxing processes or combinations of such processes in any sequence. In catalytic dewaxing the hydrofinished lubricant boiling range is reacted with hydrogen in the presence of a suitable dewaxing catalyst at conditions effective to lower the pour point of the hydrotreated lubricant boiling range. Catalytic dewaxing can also convert a portion of the hydrotreated lubricant boiling range to lower boiling materials which are separated from the heavier base stock fraction in separation unit 126. In embodiments, a first heat exchanger 142 is disposed between light end separation unit 118 and dewaxing section 140 to increase the temperature of stream 120 prior to dewaxing and a second heat exchanger 144 is disposed after dewaxing section 140 and hydrofinishing unit 122 to cool product stream 138 before hydrofinishing.

[0042] In embodiments, dewaxing section 140 includes a dewaxing catalyst that performs dewaxing primarily by isomerizing a hydrocarbon feedstock. In embodiments, the catalysts are zeolites with a unidimensional pore structure. In some embodiments, the catalyst includes 10-member ring pore zeolites, such as EU-1, ZSM-35 (or ferrierite), ZSM-11, ZSM-57, NU-87, SAPO-11, and ZSM-22. In embodiments, the dewaxing catalyst includes Theta-1, NU-10, EU-13, KZ-1, and NU-23, EU-2, EU-11, ZBM-30, ZSM-48, or ZSM-23. In embodiments, the dewaxing catalyst includes a metal hydrogenation component. The metal hydrogenation component is typically a Group VI and / or a Group VIII metal. In embodiments, the metal hydrogenation component is Pt, Pd, or a mixture thereof. In an alternative embodiment, the metal hydrogenation component can be a combination of a non-noble Group VIII metal with a Group VI metal. Suitable combinations can include Ni, Co, or Fe with Mo or W and / or Ni with Mo or W.

[0043] In embodiments, dewaxing section 140 is operated at catalytic dewaxing conditions including a temperature at a point in a range of from 300° C.-400° C. Alternatively, a temperature at a point in a range of from 200° C. to 250° C., a temperature a point in a range of from 250° C. to 350° C., a temperature a point in a range of from 350° C. to 450° C., or a temperature any ranges therebetween.

[0044] In embodiments, the dewaxing section 140 is operated at hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 3000 psig (20.68 MPa). Alternatively, the dewaxing section 140 is operated at a hydrogen partial pressure at a point in a range of 500 psig (3.44 MPa) to 1000 psig (6.89 MPa), a hydrogen partial pressure at a point in a range of 1000 psig (6.89 MPa) to 2000 psig (13.78 MPa), a hydrogen partial pressure at a point in a range of 2000 psig (13.78 MPa) to 3000 psig (20.68 MPa), or any ranges therebetween.

[0045] In embodiments, the dewaxing section 140 is operated at a LHSV at a point in a range of 0.5 to 5.0 v / v / hr. Alternatively, a LHSV at a point in a range of 0.5 to 1 v / v / hr, a LHSV at a point in a range of 1.0 to 3.0 v / v / hr, a LHSV at a point in a range of 3.0 to 5.0 v / v / hr., or any ranges therebetween.

[0046] In embodiments, the dewaxing section 140 is operated at a total treat gas ratio, i.e. the treat gas at reactor inlet and all inter-bed gas quenches, at a point in a range of 1000 scf / B to 5000 scf / B. Alternatively, the dewaxing section 140 is operated at a total treat gas ratio at a point in a range of 1000 scf / B to 2000 scf / B, at a point in a range of 2000 scf / B to 4000 scf / B, at a point in a range of 4000 scf / B to 5000 scf / B, or any ranges therebetween.

[0047] From dewaxing section 140 dewaxed lubricant boiling range product is withdrawn as product stream 138 and introduced into separation unit 126. The dewaxed lubricant boiling range product corresponds to a Group II / III base stock. Separation unit 126 is configured to separate the dewaxed lubricant boiling range product from light ends such as fuel boiling point range hydrocarbons generated in hydrofinishing unit 122 and dewaxing section 140. The fuel boiling point range hydrocarbons are withdrawn as fuel stream 130. In embodiments, separation unit 126 includes equipment such as strippers, distillation columns, fractionators, or any other equipment suitable for separating hydrofinished lubricant boiling range product from the fuel range light ends. In embodiments, product stream 128 is not blended and is the final product.Properties of Base Stock

[0048] The viscosity-temperature relationship of a lubricating oil is one of the criteria which is considered when selecting a lubricant for a particular application. Viscosity Index (VI) is an empirical, unitless number which indicates the rate of change in the viscosity of an oil within a given temperature range. Fluids exhibiting a relatively large change in viscosity with temperature are said to have a low viscosity index. A low VI oil, for example, will thin out at elevated temperatures faster than a high VI oil. Usually, the high VI oil is more desirable because it has higher viscosity at higher temperature, which translates into better or thicker lubrication film and better protection of the contacting machine elements. In embodiments, the base stocks of the present disclosure have a viscosity index (VI) of at least 80, such as a VI at a point in a range of 80-120. Alternatively, the base stocks of the present disclosure have a viscosity index at a point in a range of 80-90, at a point in a range of 90-100, at a point in a range of 100-110, at a point in a range of 110-120, at a point in a range of 120-130 or any ranges therebetween. Viscosity index is determined according to ASTM method ASTM D2270-10 (2016). In further embodiments, the base stock of the present disclosure is a Group II base stock and has a VI at a point in a range of 115-122. In further embodiments, the base stock of the present disclosure is a Group III base stock and has a VI at a point in a range of 120-124.

[0049] As used herein, “kinematic viscosity at 100° C.” will be used interchangeably with “KV100” and “kinematic viscosity at 40° C.” will be used interchangeably with “KV40”. KV100 is determined according to ASTM D445-24 and KV40 is determined according to ASTM D445-24. In embodiments, the base stock has a kinematic viscosity at 100° C. (KV100) at a point in a range of 3 cSt (centistokes) to about 8 cSt. Alternatively, the base stock has a kinematic viscosity at 100° C. at a point in a range of 3 cSt to 4 cSt, at a point in a range of 4 cSt to 5 cSt, at a point in a range of 5 cSt to 6 cSt, at a point in a range of 6 cSt to 7 cSt, at a point in a range of 7 cSt to 8 cSt, or any ranges therebetween. In embodiments, the base stock has a kinematic viscosity at 40° C. (KV40) at a point in a range of 20 cSt to about 40 cSt. Alternatively, the base stock has a kinematic viscosity at 40° C. at a point in a range of 20 cSt to 25 cSt, at a point in a range of 25 cSt to 30 cSt, at a point in a range of 30 cSt to 35 cSt, at a point in a range of 35 cSt to 40 cSt, or any ranges therebetween.

[0050] In embodiments, the base stock of the present disclosure has a pour point at a point in a range of 0° C. to −25° C. Alternatively, the base stock of the present disclosure has pour point at a point in a range of from 0° C. to −10° C., at a point in a range of from −10° C. to −20° C., at a point in a range of from −20° C. to −25° C., or any ranges therebetween. The pour point is measured according to ASTM D7346-15 (2021).

[0051] In embodiments, the base stock of the present disclosure has a density at 15° C. at a point in a range of 0.820 g / cm3 to 0.850 g / cm3. Alternatively the base stock of the present disclosure has a density at a point in a range of 0.820 g / cm3 to 0.835 g / cm3, at a point in a range of 0.835 g / cm3 to 0.840 g / cm3, at a point in a range of 0.840 g / cm3 to 0.845 g / cm3, at a point in a range of 0.845 g / cm3 to 0.850 g / cm3, or any ranges therebetween. The density is measured according to ASTM ASTMD9052.

[0052] The high temperature stability of a lubricating oil is often an important consideration when selecting a base stock for a particular application. The Noack volatility of a base stock measures the evaporative loss of engine oils exposed to elevated temperatures. The Noack volatility is measured by ASTM D5800-21, Method B test. In embodiments, the base stocks of the present disclosure have a Noack volatility of less than 15. wt. %. In embodiments, the base stock has a Noack volatility at a point in a range of 0 wt. % to 15. wt. %. Alternatively, the base stock has a Noack volatility a point in a range of 0 wt. % to 4. wt. %, a point in a range of 4 wt. % to 8. wt. %, a point in a range of 8 wt. % to 12. wt. %, or any ranges therebetween.

[0053] The low temperature viscosity of a lubricating oil is often an important consideration when selecting a base stock for a particular application. The cold cranking simulator (CCS) as outlined in ASTM D5293-20 can be used to estimate the low temperature performance of the base stock at −20° C. In embodiments, the base stock of the present application has a CCS at −20° C. at a point in a range of 500 cP to 2000 cP. Alternatively, the base stock of the present application has a CCS at −20° C. at a point in a range of 500 cP to 1000 cP, at a point 1000 cP to 1500 cP, at a point 1500 cP to 2000 cP, or any ranges therebetween.

[0054] In embodiments, the base stock of the present application has a saturates content as measured according to ASTM D7419-18 of greater than 90 wt. %. Alternatively, the base stock of the present application has a saturates content of greater than 95 wt. % or greater than 99 wt. %.

[0055] Petroleum product color serves as an indication of the degree of refinement of the petroleum product. Color is determined according to ASTM D6045-20 (Saybolt color) which has a range of 0 to +30. In embodiments, the base stock of the present application has a Saybolt color of 30 and / or +30.

[0056] In embodiments, the base stock of the present application has a total sulfur content of less than 5 parts per million (ppm) such as in a range of 0 ppm to 5 ppm as measured according to ASTM D2622-21. Alternatively, at a point in a range of 0 ppm to 1 ppm, a point in a range of 1 ppm to 3 ppm, a point in a range of 3 ppm to 5 ppm, or a point in a range of any ranges therebetween.Lubricant Compositions

[0057] In embodiments, the base stock of the present application is included in a lubricant composition. A base stock constitutes the major component of the engine or other mechanical component oil lubricant composition of the present disclosure and typically is present in an amount at a point in a range of from about 50 to about 99 weight percent, preferably at a point in a range of from about 70 to about 95 weight percent, and more preferably at a point in a range of from about 85 to about 95 weight percent, based on the total weight of the composition. As described herein, additives constitute the minor component of the engine or other mechanical component oil lubricant composition of the present disclosure and typically are present in an amount ranging from about less than 50 weight percent, preferably less than about 30 weight percent, and more preferably less than about 15 weight percent, based on the total weight of the composition.

[0058] Mixtures of base stocks may be used if desired, for example, a base stock component and a co-base stock component. The co-base stock component is present in the lubricating oils of this disclosure at a point in a range of from 1 to about 99 weight percent, preferably from about 5 to about 95 weight percent, and more preferably from about 10 to about 90 weight percent, based on the total weight of the composition. The base stock blend can be present in the engine or other mechanical component oil lubricant composition from 15 wt. % to 99 wt. %, based on the total weight of the oil lubricant composition. Alternatively, from 15 wt. % to 30 wt. %, 30 wt. % to 60 wt. %, 60 wt. % to 80 wt. %, 80 wt. % to 90 wt. %, 90 wt. % to 95 wt. %, 95 wt. % to 99 wt. %, or any ranges therebetween.

[0059] In embodiments, the base stocks further include an additional base stock such as a group I, group II, group III, group IV, group V, or combinations thereof. In embodiments, the additional base stock is present in an amount of 1 wt. % to 99 wt. % by weight of the base stock. Alternatively, from 1 wt. % to 20 wt. %, 20 wt. % to 50 wt. %, 50 wt. % to 70 wt. %, 70 wt. % to 99 wt. %, or any ranges therebetween.

[0060] The formulated lubricating oil useful in the present disclosure may contain one or more of the other commonly used lubricating oil performance additives including but not limited to antiwear additives, detergents, dispersants, viscosity modifiers, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, other viscosity modifiers, fluid-loss additives, seal compatibility agents, lubricity agents, anti-staining agents, chromophoric agents, anti-foam agents, antioxidants, anti-rust additives, anti-wear additives, pour point depressant, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. These additives are commonly delivered with varying amounts of diluent oil that may range from 5 weight percent up to greater than 90 weight percent.

[0061] When lubricating oil compositions contain one or more additives, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. As stated above, additives are typically present in lubricating oil compositions as a minor component, typically in an amount of less than 50 weight percent, preferably less than about 30 weight percent, and more preferably less than about 15 weight percent, based on the total weight of the composition. Additives are most often added to lubricating oil compositions in an amount of at least 0.1 weight percent, preferably at least 1 weight percent, more preferably at least 5 weight percent.

[0062] The lube base stocks and lubricant compositions can be employed in the present disclosure in a variety of lubricant-related end uses, such as a lubricant oil or grease for a device or apparatus requiring lubrication of moving and / or interacting mechanical parts, components, or surfaces. Useful apparatuses include engines and machines. The lube base stocks of the present disclosure are suitable for use in the formulation of automotive crank case lubricants, automotive gear oils, transmission oils, many industrial lubricants including circulation lubricant, industrial gear lubricants, grease, compressor oil, pump oils, refrigeration lubricants, hydraulic lubricants and metal working fluids. Furthermore, the lube base stocks of this disclosure may be derived from renewable sources; such base stocks may qualify as sustainable product and can meet “sustainability” standards set by industry groups or government regulations. The lube base stocks and lubricant compositions can be useful to reduce wear between surfaces such as metal surfaces in internal combustion engines, electric motors, crankcases, gearboxes, transmissions, differentials, and other mechanical devices. The base stock or lubricant composition containing the base stock can form a film on the surfaces of mechanical devices to protect the surfaces from wear.ADDITIONAL EMBODIMENTS

[0063] Accordingly, the present disclosure provides methods to form high quality Group II base stocks and Group III base stocks from used lubricating oil. The methods s may include any of the various features disclosed herein, including one or more of the following embodiments.

[0064] Embodiment 1. A method for producing base stocks comprising: introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section; contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section; contacting an effluent from the demetallization section with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating the effluent to form a hydrotreated oil; introducing the hydrotreated oil into a first separation unit and separating a light end fraction from the hydrotreated oil; introducing the hydrotreated oil into a hydrofinishing unit comprising a hydrofinishing section; contacting the hydrotreated oil with a hydrofinishing catalyst in the hydrofinishing section to hydrofinish at least a portion of the hydrotreated oil to form a hydrofinished oil; and introducing the hydrofinished oil into a second separation unit and separating a base stock fraction from the hydrofinished oil.

[0065] Embodiment 2. The method of embodiment 1 wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms the light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, and combinations thereof.

[0066] Embodiment 3. The method of any of embodiments 1-2 wherein the light end fraction comprises at least one species selected form the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof.

[0067] Embodiment 4. The method of embodiments 3 wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the first separation unit to form a fuel stream.

[0068] Embodiment 5. The method of any of embodiments 1-4 wherein hydrofinishing the portion of the hydrotreated oil further forms a second light end fraction having a boiling point at a point in a range of about 30° C. to about 370° C.

[0069] Embodiment 6. The method of any of embodiments 1-5 wherein the base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01.

[0070] Embodiment 7. The method of any of embodiments 1-6 wherein the base stock fraction has a viscosity index of about 115 to about 125 as measured according to ASTM D2270-10.

[0071] Embodiment 8. The method of any of embodiments 1-7 wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622.

[0072] Embodiment 9. The method of any of embodiments 1-8 wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18.

[0073] Embodiment 10. The method of any of embodiments 1-9 wherein the base stock fraction has a metal content less than 10 ppm as measured according to ASTM D5185-18.

[0074] Embodiment 11. The method of any of embodiments 1-10 wherein the pre-processed used lubricating oil is subjected to at least one pre-processing step prior to introducing the pre-processed used lubricating oil into the hydrotreatment unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof.

[0075] Embodiment 12. The method of any of embodiments 1-11 wherein the pre-processed used lubricating oil has a sulfur content of less than 500 ppm as measured according to ASTM D2622.

[0076] Embodiment 13. The method of any of embodiments 1-12 further comprising blending the base stock fraction with a second base stock to form a Group II base stock and wherein the base stock fraction has a saturates content of greater than 90 wt. %, a sulfur content of less than 0.03 wt. % as measured according to ASTM D2622, and a viscosity index in a range of about 80 to about 120 as measured according to ASTM D2270-10.

[0077] Embodiment 14. A method for producing base stocks comprising: introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section; contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section and demetallizing at least a portion of the pre-processed used lubricating oil; contacting the pre-processed used lubricating oil with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating at least a portion of the pre-processed used lubricating oil to form a hydrotreated oil; introducing the hydrotreated oil into a hydrodewaxing unit comprising a hydrodewaxing section and contacting the hydrotreated oil with a dewaxing catalyst in the hydrodewaxing section to form a dewaxed oil; introducing the dewaxed oil into a hydrofinishing unit comprising a hydrofinishing section and hydrofinishing the dewaxed oil to form a hydrofinished lubricant boiling range product; and introducing the hydrofinished lubricant boiling range product into a separation unit and separating a Group II / III base stock fraction.

[0078] Embodiment 15. The method of embodiment 14 wherein the base stock fraction has a viscosity index of about 80 to about 120 as measured according to ASTM D2270-10.

[0079] Embodiment 16. The method of any of embodiments 14-15 wherein the Group III base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01.

[0080] Embodiment 17. The method of any of embodiments 14-16 wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18.

[0081] Embodiment 18. The method of any of embodiments 14-17 wherein the base stock fraction has a sulfur content of less than 0.03 wt. % as measured according to ASTM D2622.

[0082] Embodiment 19. The method of any of embodiments 14-18 wherein the pre-processed used lubricating oil is subjected to at least one pre-processing step prior to introducing the pre-processed used lubricating oil into the hydrotreatment unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof.

[0083] Embodiment 20. The method of any of embodiments 14-19 wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622.

[0084] Embodiment 21. The method of any of embodiments 14-20 wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms a light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof.

[0085] Embodiment 22. The method of embodiments 21 wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the separation unit to form a fuel stream.

[0086] To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the entire scope of the disclosure.EXAMPLES

[0087] In this example, pre-processed used lubricating oil was utilized to produce Group II base stock in a pilot plant under various hydrotreating conditions. The used lubricating oil was provided as pre-processed oil having water and physical / chemical contaminants removed. Four test runs were performed. One test included a first hydrotreating catalyst at 320° C. A second test included the first hydrotreating catalyst at 329° C. A third test included a second hydrotreating catalyst at 308° C. A fourth test included the second hydrofinishing catalyst at 316° C. The results of the tests are shown in Table 1. It was observed that each of the samples have favorable properties including viscosity index above 120.TABLE 1TestGrp IImethodUnitstandardSample 1Sample 2Sample 3Sample 4CatalystCatalyst 1Catalyst 1Catalyst 2Catalyst 2System° C.320329308316kv40D445cSt29.9828.0728.4927.3627.38kV100D445cSt5.3235.275.335.175.18VI110.7121.3122.1120.5120.7SayboltD604530>30>30>3030Pour PointD7346C.−21−16.2−13.4−15−13.9density0.85060.8450.83830.84520.8448NoackD5800%11.19.178.5110.2810.07CCS @ −20 C.D529314021175116611361126SaturatesD-20007%98.999.699.799.599.5Phosphorus / D5185ppmNon-<5<5<5<5Iron / Calcium / UniqueSilicon YieldMethod

[0088] While the disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the disclosure as disclosed herein. Although individual embodiments are discussed, the present disclosure covers all combinations of all those embodiments.

[0089] While compositions, methods, and processes are described herein in terms of “comprising,”“containing,”“having,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. The phrases, unless otherwise specified, “consists essentially of” and “consisting essentially of” do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.

[0090] All numerical values within the detailed description are modified by “about” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0091] Many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure and that when numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated

Claims

1. A method for producing base stocks comprising:introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section;contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section;contacting an effluent from the demetallization section with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating the effluent to form a hydrotreated oil;introducing the hydrotreated oil into a first separation unit and separating a light end fraction from the hydrotreated oil;introducing the hydrotreated oil into a hydrofinishing unit comprising a hydrofinishing section;contacting the hydrotreated oil with a hydrofinishing catalyst in the hydrofinishing section to hydrofinish at least a portion of the hydrotreated oil to form a hydrofinished oil; andintroducing the hydrofinished oil into a second separation unit and separating a base stock fraction from the hydrofinished oil.

2. The method of claim 1 wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms the light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, and combinations thereof.

3. The method of claim 1 wherein the light end fraction comprises at least one species selected form the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof.

4. The method of claim 3 wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the first separation unit to form a fuel stream.

5. The method of claim 1 wherein hydrofinishing the portion of the hydrotreated oil further forms a second light end fraction having a boiling point at a point in a range of about 30° C. to about 370° C.

6. The method of claim 1 wherein the base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01.

7. The method of claim 1 wherein the base stock fraction has a viscosity index of about 115 to about 125 as measured according to ASTM D2270-10.

8. The method of claim 1 wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622.

9. The method of claim 1 wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18.

10. The method of claim 1 wherein the base stock fraction has a metal content less than 10 ppm as measured according to ASTM D5185-18.

11. The method of claim 1 wherein the pre-processed used lubricating oil is subjected to at least one pre-processing step prior to introducing the pre-processed used lubricating oil into the hydrotreatment unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof.

12. The method of claim 1 wherein the pre-processed used lubricating oil has a sulfur content of less than 500 ppm as measured according to ASTM D2622.

13. The method of claim 1 further comprising blending the base stock fraction with a second base stock to form a Group II base stock and wherein the base stock fraction has a saturates content of greater than 90 wt. %, a sulfur content of less than 0.03 wt. % as measured according to ASTM D2622, and a viscosity index in a range of about 80 to about 120 as measured according to ASTM D2270-10.

14. A method for producing base stocks comprising:introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section;contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section and demetallizing at least a portion of the pre-processed used lubricating oil;contacting the pre-processed used lubricating oil with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating at least a portion of the pre-processed used lubricating oil to form a hydrotreated oil;introducing the hydrotreated oil into a hydrodewaxing unit comprising a hydrodewaxing section and contacting the hydrotreated oil with a dewaxing catalyst in the hydrodewaxing section to form a dewaxed oil;introducing the dewaxed oil into a hydrofinishing unit comprising a hydrofinishing section and hydrofinishing the dewaxed oil to form a hydrofinished lubricant boiling range product; andintroducing the hydrofinished lubricant boiling range product into a separation unit and separating a Group II / III base stock fraction.

15. The method of claim 14 wherein the base stock fraction has a viscosity index of about 80 to about 120 as measured according to ASTM D2270-10.

16. The method of claim 14 wherein the Group III base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01.

17. The method of claim 14 wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18.

18. The method of claim 14 wherein the base stock fraction has a sulfur content of less than 0.03 wt. % as measured according to ASTM D2622.

19. The method of claim 14 wherein the pre-processed used lubricating oil is subjected to at least one pre-processing step prior to introducing the pre-processed used lubricating oil into the hydrotreatment unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof.

20. The method of claim 14 wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622.

21. The method of claim 14 wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms a light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof.

22. The method of claim 21 wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the separation unit to form a fuel stream.

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