Method for producing high quality lubricant base oil using refined oil fraction of waste lubricant

Abstract

The present application provides a method for manufacturing high-quality lubricating oil base oil using a refined oil fraction obtained from waste lubricants as a raw material. The method comprises purifying the waste lubricants to obtain a refined oil fraction, pre-treating the refined oil fraction, and blending the pre-treated refined oil fraction with unconverted oil (UCO) before or after vacuum distillation and catalytic dewaxing of the unconverted oil (UCO), or between vacuum distillation and catalytic dewaxing of the unconverted oil.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Korean Patent Application No. 10-2021-0108145 filed on August 17, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a method for manufacturing high-quality lubricant base oil by treating waste lubricants through a series of processing steps. More particularly, the present disclosure relates to a method for manufacturing Group III or higher grade lubricant base oil by pre-treating a refined oil fraction obtained by refining waste lubricants, blending the refined oil fraction with unconverted oil (UCO) obtained by hydrogenation reaction of fuel oil, and subjecting the mixture to vacuum distillation and catalytic dewaxing. Background Art

[0004] In the past, waste lubricants were subjected to a series of refining processes to obtain refined oil. In Korea, all refined oil was used as fuel oil. However, in other countries, a portion of refined oil was used as fuel oil, while the remaining portion was used as low-grade recycled base oil.

[0005] Generally, waste lubricants contain additives containing a large amount of impurities such as sulfur (at a concentration of about 1000 ppm to 5000 ppm), nitrogen (at a concentration of about 500 ppm to 5000 ppm), and chlorine (at a concentration of about 100 ppm to 5000 ppm). When waste lubricants are refined and used as fuel oil, there are problems in that the fuel oil causes environmental pollution during its combustion and is economically disadvantageous due to its low density and calorific value.

[0006] On the other hand, a good lubricant base oil has a high viscosity index, high stability (oxidation resistance, heat resistance, UV resistance, etc.) and low volatility. The American Petroleum Institute (API) classifies lubricant base oils according to their quality, as shown in Table 1 below.

[0007] [Table 1]

[0008]

[0009] In the above classification, the quality of lubricating base oil is evaluated as getting better and better from Class I to Class V. Among them, Class III lubricating base oil is usually manufactured by high-level hydrocracking reaction. Usually, Class III or higher grade lubricating base oil is manufactured by unconverted oil, and unconverted oil is a heavy fraction remaining without being converted into fuel oil in the fuel oil hydrocracking process. Korean Patent Publication No.1996-0013606 and the like disclose a method for manufacturing high-grade lubricating base oil from unconverted oil. As mentioned above, compared with the case of using waste lubricants as fuel oil, in the case of using waste lubricants as raw materials for the method of manufacturing Class III or higher grade lubricating base oil, there are significant advantages in environmental protection and economy. Therefore, people have actively carried out research on this technology. However, due to the limitations of the characteristics of waste lubricants (such as high impurity content and chemical composition), it is difficult to use only waste lubricants as raw materials to manufacture Class III or higher grade lubricating base oils.

[0010] (Patent Document) Korean Patent Publication No. 1996-0013606 Summary of the invention

[0011] Therefore, the present disclosure aims to provide a method for obtaining high-quality lubricant base oil through a series of steps, including: refining waste lubricants to prepare a refined oil fraction, which is used as a raw material in a method for preparing Group III or higher-grade lubricant base oil; pre-treating the refined oil; blending the pre-treated refined oil with unconverted oil so that the mixture has suitable properties and a suitable composition for use as a raw material in a method for preparing high-grade lubricant base oil; and vacuum distilling and catalytically dewaxing the mixture to obtain a final product.

[0012] In one aspect of the present disclosure, there is provided a method for manufacturing a high-quality lubricating oil base oil using a refined oil fraction obtained from a waste lubricant as a feedstock, the method comprising the steps of: purifying the waste lubricant to manufacture a refined oil fraction; pretreating the refined oil fraction; and blending the pretreated refined oil fraction with unconverted oil (UCO) before or after vacuum distillation and catalytic dewaxing of the unconverted oil or between vacuum distillation and catalytic dewaxing of the unconverted oil.

[0013] In one embodiment of the present disclosure, the step of preparing the refined oil fraction may include centrifuging the waste lubricant, distilling at atmospheric pressure, distilling at reduced pressure, and combinations thereof.

[0014] In one embodiment of the present disclosure, the pretreatment of the refined oil fraction may include subjecting the refined oil fraction to solvent extraction or hydrotreatment.

[0015] In one embodiment of the present disclosure, the solvent used for solvent extraction may be selected from the group consisting of N-methyl-2-pyrrolidone, sulfolane, DMSO, furfural, phenol, acetone, and combinations thereof.

[0016] In one embodiment of the present disclosure, the temperature may be in the range of 40°C to 120°C and the pressure may be in the range of atmospheric pressure to 10 kg / cm 2 Solvent extraction can be performed within a pressure range of 200 ℃ to 400 ℃.

[0017] In one embodiment of the present disclosure, the solvent extraction may be performed at a volume ratio of solvent to oil of 1:1 to 6:1.

[0018] In one embodiment of the present disclosure, the temperature range of the heating element may be 200°C to 400°C and the pressure may be 200 kg / cm 2 The hydrogenation reaction can be carried out within a pressure range of .

[0019] In one embodiment of the present disclosure, vacuum distillation may be performed prior to catalytic dewaxing.

[0020] In one embodiment of the present disclosure, catalytic dewaxing may be performed in the presence of a catalyst comprising a EU-2 zeolite support.

[0021] In one embodiment of the present disclosure, the blending amount of the refined oil fraction may be 3% by volume or more and 50% by volume or less relative to the unconverted oil.

[0022] In one embodiment of the present disclosure, the sulfur content in the mixture in which the refined oil fraction is blended with the unconverted oil may be less than 50 ppm, the nitrogen content may be less than 10 ppm, and the chlorine content may be less than 2 ppm.

[0023] In one embodiment of the present disclosure, the viscosity index of the lubricating base oil may be 120 or more, and the saturation may be 90% or more.

[0024] In one embodiment of the present disclosure, the lubricating oil base oil may have a Saybolt color value of 27 or more.

[0025] In one embodiment of the present disclosure, the saturation of the lubricating oil base oil may be 99%.

[0026] above.

[0027] In one embodiment of the present disclosure, the lubricating oil base oil may contain sulfur, nitrogen, and chlorine at concentrations of less than 1 ppm each.

[0028] According to the present disclosure, waste lubricants can be regenerated so that they can be used as high-quality lubricant base oil instead of fuel oil, thereby enabling the waste lubricants to be used more economically and environmentally friendly. In addition, according to the present disclosure, the refined oil fraction obtained by refining the waste lubricant is blended with the unconverted oil, and then the mixture is introduced into catalytic dewaxing. Since the refined oil fraction (or waste lubricant) contains almost no or substantially no wax components, the method of the present disclosure can produce lubricant base oil at a relatively high yield compared to the method of producing lubricant base oil using only unconverted oil as a raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart showing the steps of refining spent lubricants to prepare a refined oil fraction according to the present disclosure;

[0030] Figure 2 is a process flow chart according to one embodiment of the present disclosure;

[0031] Figure 3 is a process flow chart according to one embodiment of the present disclosure;

[0032] Figure 4 is a process flow chart according to one embodiment of the present disclosure;

[0033] Figure 5 is a process flow chart according to one embodiment of the present disclosure;

[0034] Figure 6 is a process flow diagram according to one embodiment of the present disclosure; and

[0035] Figure 7 is a process flow diagram according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] As used herein, the term "unconverted oil (UCO)" refers to the heavy fraction remaining without being converted into fuel oil by a fuel oil hydrocracking process.

[0037] As used herein, the term "waste lubricant" refers to a used lubricant. Typically, a lubricant comprises a lubricant base oil and various additives. The additives include a large number of impurities that are not suitable for use in lubricant base oils. Therefore, waste lubricants also contain a large number of impurities. For example, waste lubricants may contain 1000ppm to 5000ppm of sulfur, 500ppm to 5000ppm of nitrogen, 100ppm to 5000ppm of chlorine, and other metal impurities that may be introduced during the lubrication process. In addition, the waste lubricant has a specific gravity of 0.8 to 0.9, a kinematic viscosity (at 100°C) of 2cSt to 20cSt, a viscosity index of 60 to 150, a pour point of -18°C to 12°C, and an aromatic compound content of 10% by weight or more, a black color of 8 to 10 according to ASTM standards, and a high sediment content, and may contain some moisture.

[0038] As used herein, the term "refined oil fraction" refers to an oil component produced from waste lubricants by processes of centrifugal separation, atmospheric distillation, vacuum distillation, and combinations thereof. The refined oil fraction has a reduced impurity content compared to the original waste lubricant. For example, the sulfur content of the refined oil fraction may be less than 1000 ppm, the nitrogen content may be less than 500 ppm, and the chlorine content may be less than 2000 ppm.

[0039] In one aspect of the present disclosure, there is provided a method for manufacturing a high-quality lubricant base oil using a refined oil fraction of a waste lubricant, and the method may include refining the waste lubricant to prepare the refined oil fraction.

[0040] The step of preparing the refined oil fraction may include centrifugal separation of the spent lubricant, atmospheric distillation, vacuum distillation, and combinations thereof.

[0041] Centrifugal separation is to separate and remove impurities present in the waste lubricant by sedimentation, and can be performed at a rotation speed of about 100 rpm to 3000 rpm. Natural sedimentation can be used instead of centrifugal separation to remove impurities. However, centrifugal separation is more preferred in terms of separation speed and performance.

[0042] After most of the high-density solid impurities immiscible with the waste lubricant are removed by centrifugal separation, the waste lubricant is subjected to atmospheric distillation at atmospheric pressure. The atmospheric distillation is performed at a temperature of about 50° C. to 350° C. As the atmospheric distillation temperature increases, the fractions in the waste lubricant are distilled and fractionated in order of lower boiling points. Among the fractions fractionated by the atmospheric distillation step, the fractions having a boiling point of about 150° C. or more are collected to produce a refined oil fraction.

[0043] The oil fraction collected in the atmospheric distillation step is subjected to vacuum distillation. Vacuum distillation is performed to further fractionate the oil fraction obtained in the atmospheric distillation step. When the distillation temperature is increased at atmospheric pressure to fractionate the oil fraction, the oil fraction will crack. Therefore, this step is performed under reduced pressure and mild temperature conditions. Vacuum distillation can be performed at a pressure of less than 10 Torr and a temperature of 150°C to 350°C. In the vacuum distillation step, a fraction with a boiling point of 300°C to 550°C is collected, and the collected fraction is referred to as a refined oil fraction. The refined oil fraction has a specific gravity of about 0.8 to 1.0, a kinematic viscosity of about 4cSt to 6cSt at a temperature of 100°C, a viscosity index (VI) of about 80 to 150, and a pour point of about -20°C to 0°C. In addition, the refined oil fraction has a sulfur content of about 200ppm to 1000ppm, a nitrogen content of about 200ppm to 500ppm, and a chlorine content of about 30ppm to 2000ppm. That is, the refined oil fraction has a reduced impurity content compared to the waste lubricant. According to the ASTM standard, the refined oil fraction shows a brown color of about 5 to 6. Through centrifugal separation and two-step distillation, the refined oil fraction has a reduced content of sediment and moisture compared to the original waste lubricant.

[0044] The method of the present disclosure may include pre-treating the refined oil fraction. Pre-treating refers to a step of additionally treating the refined oil fraction to minimize the effect of the refined oil on the method and catalyst before the refined oil fraction is blended with unconverted oil and then introduced into the lubricating oil base oil manufacturing method. Pre-treating includes extracting the oil component by solvent, and hydrotreating the refined oil fraction.

[0045] Solvent extraction of refined oil fractions is: a step of blending refined oil fractions and solvents in a blending tank; a step of allowing the mixture to stand to achieve phase separation, thereby obtaining a phase in which oil is the main component; and a step of removing a phase containing a large amount of impurities. The solvent used for solvent extraction is a solvent having a higher affinity for impurities than the oil component in the refined oil fraction. As solvents, N-methyl-2-pyrrolidone (NMP), sulfolane, DMSO, furfural, phenol and acetone are generally used. The solvent has a high affinity for impurities and a low affinity for the oil component in the refined oil fraction so that the solvent is phase-separated from the oil component in the refined oil fraction. Any solvent can be used without limitation as long as it exhibits different volatility in the subsequent solvent separation step.

[0046] At a temperature of about 30°C to 200°C, preferably about 30°C to 150°C, and more preferably about 40°C to 120°C, and at atmospheric pressure to 20 kg / cm 2 In the range of atmospheric pressure to 15 kg / cm 2 In the range of atmospheric pressure to 10 kg / cm 2 The solvent extraction of the refined oil fraction is carried out at a pressure within a range of .

[0047] Furthermore, the volume ratio of the solvent used in the solvent extraction step of the refined oil fraction to the oil component in the refined oil fraction is 1: 1 to 6: 1, preferably 1: 1 to 5: 1, 1: 1 to 4: 1, 1: 1 to 3: 1, 1: 1 to 2: 1, 2: 1 to 5: 1, 2: 1 to 4: 1, 2: 1 to 3: 1, 3: 1 to 5: 1, 3: 1 to 4: 1, or 4: 1 to 5: 1. The above volume ratio is preferred from the viewpoint of the balance between the level of impurity removal by solvent extraction and the yield of the lubricating base oil subsequently produced from the pretreated refined oil fraction.

[0048] After the solvent extraction step, the refined oil fraction has a specific gravity of 0.8 to 0.9, a kinematic viscosity (at 100° C.) of 4 to 6 cSt, a viscosity index of 110 to 130, a pour point of -18° C. to -3° C., and a sulfur content of less than 150 ppm, a nitrogen content of less than 100 ppm, and a chlorine content of less than 20 ppm. That is, after solvent extraction, the refined oil fraction may have improved characteristics and reduced impurity content, may exhibit a light brown color of about 2 to 4 according to ASTM standards, and may have a reduced sediment content, compared to the original refined oil that has not been subjected to solvent extraction.

[0049] The hydrotreatment of the refined oil fraction is a step of hydrogenating the refined oil fraction at high temperature and high pressure in the presence of a catalyst to remove sulfur, nitrogen, chlorine and other metal impurities contained in the refined oil fraction, and to saturate unsaturated hydrocarbons present in the refined oil fraction.

[0050] Hydroprocessing can be carried out in the presence of a catalyst. As the catalyst for hydroprocessing, Ni-Mo based catalysts, Co-Mo based catalysts, Raney nickel, Raney cobalt and platinum based catalysts can be used, but the catalyst for hydroprocessing is not limited thereto. Any hydrogenation catalyst having the effect of promoting hydrogen saturation reaction and impurity removal reaction can be used without limitation.

[0051] The hydrotreatment is performed under the following conditions: a temperature range of about 200°C to 500°C, preferably about 250°C to 450°C, and more preferably about 300°C to 400°C; a pressure range of 50 kg / cm 2 Up to 300kg / cm 2 , preferably 50kg / cm 2 Up to 250kg / cm 2 , and more preferably 100 kg / cm 2 Up to 200kg / cm 2 ; Liquid hourly space velocity (LHSV) range is 0.1hr -1 Up to 5.0hr -1 , preferably 0.3hr -1Up to 4.0hr -1 , and more preferably 0.5 hr -1 Up to 3.0hr -1 ; The volume ratio of hydrogen to refined oil fraction ranges from 300Nm 3 / m 3 Up to 3000Nm 3 / m 3 , preferably 500Nm 3 / m 3 Up to 2500Nm 3 / m 3 , and more preferably 1000 Nm 3 / m 3 Up to 2000Nm 3 / m 3 The above conditions are within the range that does not affect the life of the dewaxing catalyst, minimizes the level of impurities such as sulfur and nitrogen present in the refined oil fraction after removal, and minimizes the yield loss of the final product as a lubricating oil base oil.

[0052] After the hydroprocessing step, the refined oil fraction has a specific gravity of 0.8 to 0.9, a kinematic viscosity (at 100°C) of 4 cSt to 6 cSt, a viscosity index of 110 to 130, a pour point of -18°C to -3°C, and a sulfur content of less than 150 ppm (preferably less than 20 ppm), a nitrogen content of less than 50 ppm (preferably less than 20 ppm), and a chlorine content of less than 1 ppm. That is, after hydroprocessing, the refined oil fraction can have improved properties and a reduced impurity content. In addition, according to the ASTM standard (corresponding to a Saybolt color scale of 16), after hydroprocessing, the refined oil can exhibit a yellow color of about 0.5 to 1.

[0053] The method may further include the step of blending unconverted oil and pretreated refined oil fraction. The blending step may be performed before the vacuum distillation and catalytic dewaxing step of the unconverted oil, after the vacuum distillation and catalytic dewaxing step, or between the vacuum distillation step and the catalytic dewaxing step. In addition, the method may include the step of blending the unrefined oil fraction with the unconverted oil before the vacuum distillation and catalytic dewaxing step of the unconverted oil. The details of the method of the present disclosure in each case are as follows, but are not limited thereto.

[0054] Model 1. Blending of pretreated refined oil fractions with unconverted oil prior to vacuum distillation and catalytic dewaxing of the unconverted oil

[0055] refer to Figure 2 and Figure 3, the refined oil fraction subjected to solvent extraction and hydrotreatment as pretreatment is blended with the unconverted oil, and then the mixture is subjected to a vacuum distillation step and a catalytic dewaxing step. According to the method of Model 1, the refined oil fraction of the pretreated waste lubricant is fractionated according to the boiling point distribution in the vacuum distillation step, thereby obtaining a final product ( Figure 2 and 3 70N, 100N and 150N fractions).

[0056] Model 2. Blending of the pretreated refined oil fraction with the unconverted oil between vacuum distillation and catalytic dewaxing of the unconverted oil

[0057] refer to Figures 4 to 6 , the refined oil fraction that has been subjected to solvent extraction and hydrotreatment as pretreatment can be blended with a portion of the fraction of unconverted oil fractionated by vacuum distillation. For example, the pretreated refined oil fraction can be blended with the 70 fraction obtained by vacuum distillation fractionation ( Figure 5 ), or can be blended with the 100 and 150 fractions obtained by vacuum distillation fractionation ( Figure 4 and 6 ). As described above, when the pre-treated refined oil fraction of the waste lubricant is blended with each fraction obtained by vacuum distillation fractionation, a lubricating base oil having a desired boiling point can be prepared by blending the refined oil fraction with an unconverted oil fraction having a specific boiling point. In the step of blending the refined oil fraction with each fraction of the unconverted oil and catalytically dewaxing each mixture, even if there is a problem in processing any one of the blending stocks, it does not affect the lubricating base oil manufacturing method in which the other blending stocks are also processed.

[0058] In this method configuration, relative to unconverted oil, the blending amount of the pretreated refined oil fraction ranges from about 3 volume % to 50 volume %, preferably from about 5 volume % to 45 volume %, from about 5 volume % to 40 volume %, from about 5 volume % to 35 volume %, from about 5 volume % to 30 volume %, from about 5 volume % to 25 volume %, from about 5 volume % to 20 volume %, from about 5 volume % to 15 volume %, from about 5 volume % to 10 volume %, from about 7 volume % to 40 volume %, from about 7 volume % to 35 volume %, from about 7 volume % to 25 volume %, from about 7 volume % to 20 volume % or from about 7 volume % to 15 volume %. More preferably, relative to unconverted oil, the blending amount of the pretreated refined oil fraction is in the range of about 7 volume % to 10 volume %. The pretreated refined oil fraction contains almost no wax component. Therefore, as mentioned above, the pour point is as low as -18°C to -3°C. When the pretreated refined oil fraction is blended with an unconverted oil having a high pour point of about 42°C, the fluidity of the blended raw material increases, so that the raw material can be easily transported even at low temperatures. When the blending amount of the pretreated refined oil fraction is less than 3% by volume, the effect of increasing fluidity is not significant, so that the blended raw material cannot be easily transported from one step to another. When the blending amount of the pretreated refined oil fraction exceeds 20% by volume, the blended raw material is not suitable as a raw material for manufacturing high-grade lubricant base oil due to impurities and low viscosity index contained in the refined oil fraction.

[0059] In Models 1 and 2, the blended stock prepared by blending the unconverted oil and the refined oil fraction of the waste lubricant has a specific gravity of 0.8 to 0.9, a kinematic viscosity (at 100° C.) of 3 cSt to 8 cSt, a viscosity index of 120 to 140, a pour point of -18° C. to 45° C., a sulfur content of less than 20 ppm, a nitrogen content of less than 5 ppm, and a chlorine content of less than 1 ppm. That is, the blended stock of Models 1 and 2 is similar in performance to the Group III base oil, except for the pour point. In addition, the blended stock exhibits a yellow color of about 0.5 to 1 according to the ASTM standard.

[0060] Model 3. Blending of unpretreated refined oil fractions with unconverted oil prior to vacuum distillation and catalytic dewaxing of the unconverted oil

[0061] refer to Figure 7 , the blended raw material of the unpretreated refined oil fraction and the unconverted oil blend is introduced into the vacuum distillation step, thus fractionated according to the boiling point, and each fraction is introduced into the catalytic dewaxing step. Thus, the lubricating oil base oil is obtained. In this way, when the refined oil fraction is blended with the unconverted oil without pretreatment, the advantage is that the process can be simplified. However, in order to control the impurity content in the blended raw material, the blending amount of the refined oil fraction needs to be lower than the blending amount in models 1 and 2.

[0062] In the case of Model 3, since the refined oil fraction is not subjected to a pretreatment step such as solvent extraction or hydrotreatment, the impurity content of the blended stock in Model 3 is higher than that of the blended stock in Models 1 and 2. This is a process limitation of the entire advanced lubricant base oil manufacturing method. In Model 3, the blending amount of the refined oil fraction is limited to 5% by volume or less relative to the unconverted oil.

[0063] In addition, the blending stock of Model 3 has similar properties to the blending stocks of Models 1 and 2, but has a sulfur content of 100 ppm to 300 ppm, a nitrogen content of 50 ppm to 100 ppm, and a chlorine content of 5 ppm to 20 ppm. That is, the blending stock of Model 3 exhibits a higher impurity content than each of Models 1 and 2.

[0064] A vacuum distillation step of the unconverted oil may be performed before the catalytic dewaxing step. In the case where the unconverted oil and the refined oil fraction are blended before the vacuum distillation step, a vacuum distillation step of the blended raw material may be performed before the catalytic dewaxing step. Typically, the general process sequence is to fractionate and obtain a lubricating base oil with a desired boiling point by distilling the product produced by catalytic dewaxing under reduced pressure. However, in the method disclosed herein, vacuum distillation is first performed, and only the fraction with the desired boiling point is catalytically dewaxed. Therefore, only products with a desired boiling point can be produced, the output of the product can be controlled, and the process scale can be reduced, thereby reducing the operating cost of the process.

[0065] The vacuum distillation step for the unconverted oil may be performed under the same process conditions as the vacuum distillation of the spent lubricant in the step of producing the refined oil fraction, thereby fractionating the unconverted oil or the blending stock according to boiling points.

[0066] Catalytic dewaxing selectively isomerizes the wax components contained in the unconverted oil or blended stock to improve low temperature performance (to ensure a low pour point) and maintain a high viscosity index (VI). The present disclosure is intended to achieve improvements in efficiency and yield by improving the catalyst used in the catalytic dewaxing process. The catalytic dewaxing step may include a dewaxing reaction and a subsequent hydrofinishing reaction.

[0067] Generally, the main reaction of the catalytic dewaxing reaction is to convert normal paraffins into isoparaffins through isomerization reaction to improve low temperature performance. It is reported that the catalyst used here is mainly a bifunctional catalyst. The bifunctional catalyst consists of two active components: a metal active component (metal site) for hydrogenation / dehydrogenation reaction and a carrier (acidic site) for skeletal isomerization using carbon cations. The catalyst with a zeolite structure is usually composed of an aluminosilicate carrier and at least one metal selected from Group 8 metals and Group 6 metals.

[0068] The dewaxing catalyst used in the present disclosure comprises a carrier having an acidic site selected from molecular sieves, alumina and silica-alumina, and one or more hydrogenation metals selected from elements of Groups 2, 6, 9 and 10 of the periodic table. In particular, among the metals of Groups 9 and 10 (i.e., Group VIII), Co, Ni, Pt and Pd are preferably used, and among the metals of Group 6 (i.e., Group VIB), Mo and W are preferably used.

[0069] The types of carriers with acidic sites include molecular sieves, alumina, silica-alumina, etc. Among them, molecular sieves refer to crystalline aluminosilicates (zeolites), SAPO, ALPO, etc. Medium-pore molecular sieves with 10-membered oxygen rings are used, such as SAPO-11, SAPO-41, ZSM-11, ZSM-22, ZSM-23, ZSM-35 and ZSM-48, and macroporous molecular sieves with 12-membered oxygen rings can be used.

[0070] In particular, in the present disclosure, EU-2 zeolite with a controlled phase transition degree can be preferably used as a carrier. After the pure zeolite is generated, the synthesis conditions may change, or if the synthesis continues for more than a predetermined time, the synthesized zeolite crystals may gradually transform into a more stable phase. This phenomenon is called the phase transition of the zeolite. It is confirmed that according to the phase transition degree of the zeolite, the isomerization selectivity is improved, and excellent performance is also shown in the catalytic dewaxing reaction using the zeolite.

[0071] The lubricating base oil produced by the above method may be a high-grade lubricating base oil having Group III or higher in the above API classification. More specifically, the lubricating base oil has a viscosity index of 120 or more, preferably 120 to 140, 120 to 135, 120 to 130, 120 to 125, 125 to 140, 125 to 135, 125 to 130, 130 to 140 or 130 to 135, and a saturation of 90% or more, preferably 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more or 99% or more.

[0072] Furthermore, since the contents of impurities such as sulfur, nitrogen, and chlorine are each 1 ppm or less, the lubricating base oil can contain almost no impurities.

[0073] The lubricating base oil may have a Saybolt color value of 27 or more when measured by ASTM D 156. When the Saybolt color value of the lubricating base oil is 27 or more, the lubricating base oil is considered to be a lubricating base oil having stability equivalent to a colorless grade. The colorless grade lubricating base oil has a sulfur and nitrogen content of less than 1 ppm, a saturation of 99% or more, and an aromatic compound content of less than 1%. The lubricating base oil is more stable than a conventional API Group III lubricating base oil.

[0074] As measured by ASTM D 2008, the lubricating base oil may show an absorbance of 2.5 or less at UV260nm to 350nm, and an absorbance of 0.7 or less at UV325nm. Here, the absorbance at a wavelength of 260nm to 350nm indicates that the test material contains a component having 3 or more aromatic rings, and the absorbance at a wavelength of 325nm indicates that the test material contains a component having 3 to 7 aromatic rings. The lubricating base oil shows low absorbance at these wavelengths. That is, the lubricating base oil has a low aromatic compound content and thus has high stability.

[0075] The properties and impurity levels of exemplary oils at various steps of the process are shown in the table below.

[0076] [Table 2]

[0077]

[0078] (Here, preprocessing 1 or preprocessing 2 is selectively performed)

[0079] Hereinafter, preferred embodiments are presented to help understand the present disclosure, but the following embodiments are provided only for easier understanding of the present disclosure, and thus the present disclosure is not limited thereto.

[0080] Example

[0081] 1. Determination of the properties of the lubricating base oil produced by the method of the present disclosure

[0082] Waste lubricants having a sulfur content of about 2000 ppm, a nitrogen content of about 1500 ppm, and a chlorine content of about 1500 ppm were centrifuged at a speed of about 300 rpm, and then subjected to atmospheric distillation and vacuum pressure distillation to obtain a refined oil fraction of the waste lubricant. The obtained refined oil fraction was hydrotreated, and the treated refined oil fraction was blended with unconverted oil as in Model 1, so that the blending ratio of the treated refined oil fraction to the unconverted oil was 25 volume %. The obtained mixture was subjected to vacuum distillation and catalytic dewaxing to produce a lubricating oil base oil. Here, atmospheric distillation was performed at a temperature of 50° C. to 350° C. and at atmospheric pressure. The process conditions of vacuum distillation are shown in Table 3 below.

[0083] [Table 3]

[0084] Vacuum distillation process conditions

[0085] temperature 100℃ to 350℃ pressure 10Tor

[0086] The process conditions for the hydrotreating are shown in Table 4 below.

[0087] [Table 4]

[0088] Hydrotreating process conditions

[0089] temperature 350℃ pressure <![CDATA[150kg / cm 2 ]]> catalyst Ni-Mo catalyst

[0090] In addition, in the presence of a hydrogenation catalyst, at a temperature of 300°C and a pressure of 150 kg / cm 2 The catalytic dewaxing was carried out using EU-2 zeolite as a carrier at a pressure of 100°C. During the process, the performance and various characteristics of the lubricating base oil prepared by the method of Model 1 were measured. The measurement results showed that the lubricating base oil had a specific gravity of 0.84, a kinematic viscosity of 7.3 cSt at 100°C, a viscosity index (VI) of 129, and a pour point of -33°C. In the lubricating base oil, the contents of sulfur, nitrogen, and chlorine were each less than 1 ppm. That is, no impurities were contained except for trace amounts of unavoidable impurities.

[0091] In addition to the above, the properties of the lubricating base oils were measured and are shown in Table 5 below.

[0092] [Table 5]

[0093] Properties of Lubricating Oil Base Oils Produced by the Method of Model 1 of the Present Disclosure

[0094] project Test Method Specification Appearance Visual observation Bright & Clean Saybolt color value ASTM D 156 Min.+27 Saturation, % ASTM D 7419 Min.99 UV 260nm to 350nm ASTM D 2008 Max.3.0 UV 325nm ASTM D 2008 Max.1.0 Viscosity Index ASTM D 2270 Min.120

[0095] The viscosity index of the lubricating base oil is at least 120, and the saturation is at least 95%, indicating that the lubricating base oil meets the conditions required for the Group III lubricating base oil shown in Table 1. When visually observed and evaluated, the base oil has a bright and clean color. When measured according to ASTM D 156, the color is a Saybolt color value of 27 or more. That is, the lubricating base oil is a lubricating base oil with a colorless grade, and the lubricating base oil has high thermal stability at high temperatures.

[0096] Furthermore, the lubricating base oil exhibited a low absorbance of at most 3.0 (at most 1.0 at a wavelength of 325 nm) when measured for UV at a wavelength of 260 nm to 350 nm, and particularly at a wavelength of 325 nm according to ASTM D 2008. It was confirmed that the lubricating base oil had high stability to UV.

[0097] 2. Evaluation of product yield of lubricating base oil blended or not blended with refined oil fraction of waste lubricant

[0098] Lubricating oil base oil was obtained under the same process conditions as in Example 1, except that the refined oil fraction of the waste lubricant was blended with the unconverted oil. The results of comparing the yield of this case with the yield of Example 1 are shown in Table 6 below.

[0099] [Table 6]

[0100]

[0101] As described above, when the raw material blended with the unconverted oil is used as a raw material to manufacture the lubricating base oil, the lubricating base oil shows a yield equal to or slightly higher than the case where only the unconverted oil is used as the raw material. The reason is considered to be the fact that the refined oil fraction does not contain wax components such as normal paraffins, while the unconverted oil contains about 15% normal paraffins. As described above, when a predetermined amount of the refined fraction of the waste lubricant is blended with the unconverted oil and the mixture is used as a raw material for preparing the lubricating base oil, the stability and yield of the final product as the lubricating base oil can be improved. In addition, the method is also advantageous in terms of environmental protection because the waste lubricant is recycled as the lubricating base oil.

Claims

1. A method for producing high-quality lubricating oil base oil using a refined oil fraction of waste lubricants, the method comprising: preparing a refined oil fraction by refining waste lubricants; Pretreating the refined oil fraction; as well as The pretreated refined oil fraction is blended with the unconverted oil prior to vacuum distillation and catalytic dewaxing of the unconverted oil or between the vacuum distillation and the catalytic dewaxing, wherein the vacuum distillation is performed prior to the catalytic dewaxing.

2. The method according to claim 1, wherein the preparation of the refined oil fraction comprises: Centrifuging the waste lubricant; performing atmospheric distillation; Perform vacuum distillation; or a combination thereof.

3. The method according to claim 1, wherein the pretreatment of the refined oil fraction comprises subjecting the refined oil fraction to solvent extraction or hydrotreatment.

4. The method according to claim 3, wherein the solvent used for the solvent extraction is selected from the group consisting of: N-methyl-2-pyrrolidone, sulfolane, DMSO, furfural, phenol, acetone and combinations thereof.

5. The method according to claim 3, wherein the temperature ranges from 40°C to 120°C and the pressure ranges from atmospheric pressure to 10 kg / cm 2 The solvent extraction is performed within a pressure range of .

6. The method of claim 3, wherein the solvent extraction is performed at a volume ratio of solvent to oil ranging from 1:1 to 6:

1.

7. The method according to claim 3, wherein the temperature ranges from 200°C to 400°C and the pressure is 100 kg / cm 2 Up to 200kg / cm 2 The hydroprocessing is carried out within a pressure range of 8. The process of claim 1, wherein the catalytic dewaxing is carried out in the presence of a catalyst comprising a EU-2 zeolite support.

9. The method according to claim 1, wherein the amount of the refined oil fraction blended with the unconverted oil is 3 volume % or more and 50 volume % or less.

10. The method of claim 1, wherein the blended feed obtained by blending the refined oil fraction with the unconverted oil has a sulfur content of less than 50 ppm, a nitrogen content of less than 10 ppm, and a chlorine content of less than 2 ppm.

11. The method according to claim 1, wherein the lubricating base oil has a viscosity index of 120 or more and a saturation of 90% or more.

12. The method according to claim 11, wherein the lubricating oil base oil has a Saybolt color value of 27 or more.

13. The method according to claim 11, wherein the saturation of the lubricating oil base oil is 99% or more.

14. The method of claim 11, wherein the lubricating oil base stock contains sulfur, nitrogen, and chlorine at concentrations each of less than 1 ppm.

Images