Lubricating base oil manufacturing process utilizing waste lubricating oil purification fraction, and lubricating base oil manufactured thereby

Abstract

To provide a lubricating base oil manufacturing process utilizing a waste lubricating oil purification fraction.SOLUTION: The process includes the steps of: providing a purification fraction by refining waste lubricating oil; pretreating the purification fraction, in which the purification fraction has a nitrogen content of less than 30 ppm; and blending the pretreated purification fraction with unconverted oil (UCO) before or after subjecting the unconverted oil to vacuum distillation and catalytic dewaxing or between the vacuum distillation and the catalytic dewaxing of the unconverted oil. The process makes it possible to recycle waste lubricating oil into high-grade lubricating base oil rather than fuel oil, thereby making it possible to use waste lubricating oil in a more economical and environmentally friendly way.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a process for producing lubricant base oil utilizing waste lubricant refinery fractions and the lubricant base oil produced thereby. [Background technology]

[0002] Waste lubricating oil goes through a series of refining processes and is entirely used as fuel oil in Japan, while part of it is used as fuel oil and another part is used as low-grade recycled base oil overseas.

[0003] Usually, waste lubricating oil contains additives, which contain large amounts of impurities such as sulfur (about 1000 to 5000 ppm), nitrogen (about 500 to 5000 ppm), and chlorine (about 100 to 5000 ppm). Therefore, if this is refined and used as fuel oil, it will cause environmental pollution when burned, and since it has a low density and calorific value, using it as fuel oil is also economically disadvantageous.

[0004] On the other hand, generally speaking, a good lubricant base oil has a high viscosity index, excellent stability (oxidation, heat, UV, etc.), and low volatility. The American Petroleum Institute (API) classifies lubricant base oils according to their quality as shown in Table 1 below.

[0005] [Table 1]

[0006] In the above classification, the quality of the lubricant base oil is evaluated as being superior from Group I to Group V, and among them, Group III lubricant base oils are generally produced by advanced hydrocracking reactions. Usually, unconverted oil, which is a heavy fraction that is not converted to fuel oil in the fuel oil hydrocracking process, is used as a feedstock for producing high-grade lubricant base oils of Group III or higher, and Patent Document 1 and the like disclose a method for producing high-grade lubricant base oils using unconverted oil as a feedstock. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-1996-0013606 Summary of the Invention [Problem to be solved by the invention]

[0008] The present disclosure aims to provide a process for producing a lubricant base oil utilizing a waste lubricant refinery fraction and the lubricant base oil produced thereby. [Means for solving the problem]

[0009] According to one aspect of the disclosure, there is provided a process for producing lubricant base oils utilizing a used lubricant refinery fraction, the process including refining a used lubricant to produce a refined fraction, pre-treating the refined fraction, wherein the pre-treated refined fraction contains less than 30 ppm nitrogen, and blending the pre-treated refined fraction with unconverted oil (UCO) prior to, after, or between vacuum distillation and catalytic dewaxing of the unconverted oil.

[0010] According to one embodiment, the step of producing the refined fraction may include centrifuging the used lubricating oil, atmospheric distilling, first and second vacuum distilling, or a combination thereof.

[0011] According to one embodiment, the pre-treatment step of the refined fraction may comprise a step of solvent extraction of the refined fraction.

[0012] According to one embodiment, the solvent used in the solvent extraction may include N-Methyl-2-Pyrrolidone, Sulfolane, DMSO, Furfural, Phenol, Acetone, or a combination thereof.

[0013] According to one embodiment, the solvent extraction is carried out at a temperature of 50 to 150°C and at atmospheric pressure of 5 kg / cm 2 The reaction can be carried out under pressure.

[0014] According to one embodiment, the solvent extraction may be carried out under a volume ratio of solvent to oil of 1:1 to 10:1.

[0015] According to one embodiment, the vacuum distillation may be carried out prior to the catalytic dewaxing.

[0016] According to one embodiment, the catalytic dewaxing may be carried out in the presence of a catalyst comprising an EU-2 zeolite support.

[0017] According to one embodiment, the blending amount of the refined fraction relative to the unconverted oil may be 1% to 10% by volume based on the total blending loss.

[0018] According to one embodiment, the blended stock after blending of the refined distillate with the unconverted oil may have 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.

[0019] According to one embodiment, there is provided a lubricant base oil produced by the process described above, and the lubricant base oil may have a viscosity index of 120 or greater and a saturation level of 90% or greater.

[0020] According to one embodiment, the lubricant base oil may have a saybolt color value of 27 or greater.

[0021] According to one embodiment, the lubricant base oil may have a saturation level of 99% or greater.

[0022] According to one embodiment, the lubricant base oil may have a sulfur, nitrogen and chlorine content of less than 1 ppm each. Effect of the Invention

[0023] According to the manufacturing process of lubricant base oil using the waste lubricant refined fraction of the present disclosure, the waste lubricant can be recycled into high-grade lubricant base oil instead of fuel oil, so that the waste lubricant can be used more economically and environmentally friendly. In addition, the refined fraction obtained by refining the waste lubricant is blended with unconverted oil, which is then introduced into catalytic dewaxing, where the refined fraction (or the waste lubricant) contains little or essentially no wax components, so that the lubricant base oil can be obtained at a higher yield than in the process of manufacturing the lubricant base oil using only unconverted oil as a feedstock. [Brief description of the drawings]

[0024] [Figure 1] 1 is a flow diagram illustrating a process for refining used lubricating oil to produce a refined fraction according to one embodiment. [Diagram 2] 1 is a process flow diagram according to one embodiment. [Diagram 3] 1 is a process flow diagram according to one embodiment. [Figure 4] 1 is a process flow diagram according to one embodiment. [Diagram 5] 1 is a process flow diagram according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] As used herein, the term "unconverted oil (UCO)" refers to the heavy fraction remaining in a fuel oil hydrocracking process that is not converted into fuel oil.

[0026] The term "used lubricating oil" used in this application refers to lubricating oil after use. Generally, various additives are added to lubricating base oil, but the additives contain a large amount of impurities that are not suitable for use as lubricating base oil, so the used lubricating oil can also contain a large amount of impurities. For example, the used lubricating oil can contain 1000 to 5000 ppm of sulfur, 500 to 5000 ppm of nitrogen, 100 to 5000 ppm of chlorine, and other metal impurities that can flow into the lubricating action. In addition, the used lubricating oil has a specific gravity of 0.8 to 0.9, a kinematic viscosity at 100 ° C of 2 to 20 cSt, a viscosity index of 60 to 150, a pour point of -18 to 12 ° C, and an aromatic content of 10 wt% or more, is black in color with an ASTM standard of about 8 to 10, has a high sediment content, and contains some water.

[0027] The term "refined fraction" as used herein refers to a fraction obtained after the used lubricating oil is subjected to centrifugation, atmospheric distillation, first and second vacuum distillation, or a combination thereof, and has a reduced impurity content compared to the used lubricating oil. For example, the refined fraction may have a sulfur content of less than 1000 ppm, a nitrogen content of less than 500 ppm, and a chlorine content of less than 2000 ppm.

[0028] According to one aspect of the present invention, there is provided a process for producing lubricant base oil utilizing a waste lubricant refinery fraction, said process comprising refining the waste lubricant to produce a refinery fraction.

[0029] The step of refining the used lubricant to produce a refined fraction may include centrifuging the used lubricant, distilling it at atmospheric pressure, distilling it at first and second reduced pressures, or a combination thereof.

[0030] The centrifugal separation step is for separating and removing impurities present in the waste lubricating oil by precipitation, and can be performed at a rotation speed of about 100 rpm to 3000 rpm. Although natural precipitation of impurities is also possible instead of the centrifugation, centrifugation is more preferable in terms of separation speed and performance.

[0031] The waste lubricating oil after the solid phase impurities that are high density and not mixed with the waste lubricating oil are primarily removed by centrifugation can be introduced into atmospheric distillation under atmospheric pressure. Atmospheric distillation is carried out at a temperature of about 50°C to 350°C, and as the atmospheric distillation temperature increases, the fractions in the waste lubricating oil are distilled and separated in order of decreasing boiling point. Among the fractions separated in the atmospheric distillation step, fractions having a boiling point of about 150°C or higher can be collected for producing refined fractions. In addition, fractions having a boiling point of less than 150°C can be used for other purposes, such as fuel oil, rather than as a feedstock for the subsequent lubricating base oil production process.

[0032] The fraction collected in the atmospheric distillation step can be introduced into the first vacuum distillation step. This is for more detailed fractionation of the fraction obtained in the atmospheric distillation step, and can be carried out under reduced pressure and mild temperature conditions because cracking of the fraction may occur if the distillation temperature is increased for detailed fractionation of the fraction under atmospheric pressure. The first vacuum distillation can be carried out at a pressure of 10 torr or less and at a temperature of 150 to 350°C. During the first vacuum distillation step, a fraction having a boiling point of 300 to 550°C is collected, which is called vacuum refined oil. The vacuum refined oil can have a specific gravity of about 0.8 to 1.0, a kinematic viscosity of about 4 to 6 cSt 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 vacuum refined oil has a sulfur content of about 200 to 1000 ppm, a nitrogen content of about 200 to 500 ppm, and a chlorine content of about 30 to 2000 ppm, and therefore has a reduced impurity content compared to the waste lubricating oil. The vacuum refined oil has a color close to brown, about 5 to 6 based on ASTM, and due to the centrifugation and two-step distillation, the vacuum refined oil can have a sediment and moisture content that is significantly reduced compared to the sediment and moisture content that existed in the waste lubricating oil before refining.

[0033] The vacuum refined oil obtained after the first vacuum refinement can be introduced into the second vacuum refinement step. The second vacuum refinement is a step for removing a light fraction that may be present in the vacuum refined oil but has a boiling point in a range overlapping with the solvent used in the subsequent solvent extraction. The second vacuum distillation can be performed at a pressure of 10 torr or less and a temperature of 150 to 300°C. The refined fraction obtained by the second vacuum distillation can have a kinematic viscosity at 100°C of about 4.5 to 6 cSt, a viscosity index of about 110 to 150, and a pour point of about -20°C to -8°C at a temperature of 100°C. In addition, the refined fraction has a sulfur content of about 200 to 500 ppm, a nitrogen content of about 200 to 400 ppm, and a chlorine content of about 30 to 200 ppm, and therefore can have a reduced impurity content compared to the vacuum refined oil. That is, the second vacuum distillation step removes fractions having a boiling point that overlaps with the solvent used in the subsequent solvent extraction step, thereby enabling the purity of the solvent recovered during recovery of the solvent used after the solvent extraction to be maintained at a high level, and the impurity content of the refined fraction, which is the feedstock, to be further reduced. In addition, the second vacuum distillation step removes fractions having a low boiling point that are not required for the production of base oil in advance, thereby reducing the amount of feed introduced into the solvent extraction step, thereby reducing the process load.

[0034] The process can include pre-treating the refined fraction, which refers to further processing the refined fraction to minimize its effects on the process and catalysts before it is introduced into the lubricant base oil production process by blending with unconverted oil, and can include solvent extraction of the refined fraction.

[0035] Solvent extraction of the refined fraction is a step of mixing the refined fraction and a solvent in a mixing tank, and then allowing the mixture to stand to separate into phases, thereby obtaining a phase mainly composed of the fraction to be obtained, and removing a phase containing a large amount of impurities. The solvent used in the solvent extraction may be a solvent having a higher affinity for impurities than the oil components in the refined fraction. In one embodiment, the solvent used in the solvent extraction may include N-Methyl-2-Pyrrolidone (NMP), Sulfolane, DMSO, Furfural, phenol, acetone, or a combination thereof. The solvent has a high affinity for impurities and a low affinity for the refined fraction, so it can be used without restrictions as long as there is a difference in volatility for subsequent solvent separation, since it is phase-separated from the refined fraction.

[0036] The solvent extraction of the purified fraction can be carried out at a temperature of about 50 to 150° C., preferably about 55 to 120° C., and more preferably about 60 to 100° C. The solvent extraction of the purified fraction can be carried out at a pressure of atmospheric pressure to 5 kg / cm. 2 , preferably 1 to 4 kg / cm 2 , more preferably 2 to 3 kg / cm 2 Solvent extraction under the above conditions is effective in reducing the impurity content, especially the nitrogen content, in the refined fraction, and the reduction in the impurity content in the refined fraction can make the operating conditions of the subsequent process steps milder, thereby increasing the efficiency of the entire lubricant base oil production process.

[0037] The volume ratio of the solvent used in the solvent extraction step of the refined fraction to the oil component in the refined fraction may be 1:1 to 10:1, preferably 2:1 to 8:1, 2:1 to 7:1, 2:1 to 6:1, 2:1 to 5:1, 3:1 to 8:1, 3:1 to 7:1, 3:1 to 6:1, 4:1 to 8:1, 4:1 to 7:1, and 5:1 to 8:1. The volume ratio of the solvent used in the solvent extraction step of the refined fraction to the oil component in the refined fraction may be most preferably 1:1 to 1.5:1. The volume ratio is preferable from the viewpoint of the balance between the level of removal of impurities by solvent extraction and the yield of lubricating base oil produced from the refined fraction pretreated thereafter.

[0038] The refined fraction after the solvent extraction step may have a specific gravity of 0.8-0.9, a kinematic viscosity at 100°C of 4-6 cSt, a viscosity index of 110-130, a pour point of -18 to -3°C, a sulfur content of less than 150 ppm, and a chlorine content of less than 20 ppm.

[0039] In particular, the refined fraction after the solvent extraction step, i.e., the pretreated refined fraction, may contain less than 30 ppm nitrogen, preferably less than 20 ppm, more preferably less than 10 ppm. Thus, the pretreated refined fraction may have improved properties and reduced impurity content due to the solvent extraction, and may exhibit a light brown color of about 2-4 on the ASTM scale and have a reduced sediment content compared to the refined fraction.

[0040] The process includes blending the unconverted oil with the pretreated refinery fraction, the blending step being performed before the vacuum distillation and catalytic dewaxing step for the unconverted oil; after the vacuum distillation and catalytic dewaxing step, or between the vacuum distillation and catalytic dewaxing step. Furthermore, the process can include blending the unpretreated refinery fraction with the unconverted oil before the vacuum distillation and catalytic dewaxing step for the unconverted oil. The configuration of the above process in each case is illustratively as follows, but is not limited thereto.

[0041] Model 1. Pretreated refinery fraction blended with unconverted oil prior to vacuum distillation and catalytic dewaxing of unconverted oil Referring to Figure 2, the refinery fraction introduced into the solvent extraction as pretreatment is blended with unconverted oil and then introduced into the vacuum distillation and catalytic dewaxing steps. According to the process of Model 1, the pretreated waste lubricant refinery fraction is fractionated according to boiling point distribution in the vacuum distillation step, and can be dispersed into all the final products of Group III or higher lubricant base oil (70N, 100N and 150N fractions in Figure 2).

[0042] Model 2. Blending of pretreated refinery fraction with unconverted oil between vacuum distillation and catalytic dewaxing of unconverted oil 3 and 4, the refined fraction after being introduced into the solvent extraction step as a pretreatment can be blended with a part of the components of the unconverted oil fractionated by vacuum distillation. For example, the pretreated refined fraction can be blended with the 70D (distillate) fraction fractionated by vacuum distillation (FIG. 4), or with the 100 and 150D (distillate) fractions fractionated by vacuum distillation (FIG. 3). As described above, when the pretreated waste lubricant refined fraction is blended individually with each fraction fractionated after vacuum distillation of the unconverted oil, it is possible to produce a lubricant base oil having a desired boiling point by blending the refined fraction with a fraction of the unconverted oil having a specific boiling point, and in the step of blending the refined fraction with each fraction and catalytically dewaxing it, even if there is a problem in the processing of any one blending raw material, this has the advantage that it does not affect the lubricant base oil manufacturing process by processing the other blending raw materials.

[0043] In the above process configuration, the blending amount of the pretreated refined fraction relative to the entire blended raw material may be about 1% to 10% by volume. The blending amount of the pretreated refined fraction relative to the entire blended raw material may be preferably about 1.2% to 8%, more preferably about 1.5% to 5%, by volume. The blending amount of the pretreated refined fraction relative to the entire blended raw material may be most preferably about 2% to 4% by volume. Since the pretreated refined fraction contains almost no wax components, as described above, it has a low pour point of -18°C to -3°C, and when blended with unconverted oil having a high pour point of about 42°C, the fluidity of the blended raw material increases and it is easy to transport even at low temperatures. However, when the blending amount of the pretreated refined fraction is less than 1% by volume, such a fluidity increasing effect is not large, so that it is not easy to transport at each step of the process. When the blending amount of the pretreated refined fraction exceeds 10%, the blended raw material may not be suitable as a raw material for producing high-grade lubricant base oil due to impurities contained in the refined fraction and a low viscosity index.

[0044] As mentioned above, the blended stock obtained by blending the pretreated refinery fraction having a low impurity content with the unconverted oil also has a low impurity content, which can reduce the load on the catalyst in the subsequent dewaxing step. That is, the low impurity content of the blended stock has the advantage that the process temperature of the dewaxing step can be reduced.

[0045] In the models 1 and 2, the blended stock produced by blending the unconverted oil with the refined fraction has a specific gravity of 0.8-0.9, a kinematic viscosity at 100°C of 3-8 cSt, a viscosity index of 120-140, a pour point of 12-45°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 stocks of the models 1 and 2 are similar to Group III lubricant base oils in properties other than the pour point. The blended stocks also exhibit a yellow color of about 0.5-1 based on ASTM.

[0046] Model 3. Unpretreated refinery fraction blended with unconverted oil prior to vacuum distillation and catalytic dewaxing of unconverted oil 5, a blended feedstock containing refined fractions that have not been pretreated and unconverted oil is introduced into a vacuum distillation step and fractionated according to boiling point, and each fraction is introduced into a catalytic dewaxing step to obtain each lubricant base oil product. Blending refined fractions with unconverted oil without pretreatment has the advantage of simplifying the process, but the blending amount of refined fractions must be adjusted to be lower than that of Models 1 and 2 above in order to control the impurity content in the blended feedstock.

[0047] In the case of Model 3, the refined fraction does not undergo pretreatment steps such as solvent extraction, so the impurity content of the blended raw material is higher than in Models 1 and 2, which corresponds to a process limiting factor for the entire high-grade lubricant base oil manufacturing process. In Model 3, the blending amount of refined fraction to unconverted oil is limited to 5% or less by volume.

[0048] The blended raw material of Model 3 has properties similar to those of the blended raw materials of Models 1 and 2, but has a sulfur content of 100 to 300 ppm, a nitrogen content of 50 to 100 ppm, and a chlorine content of 5 to 20 ppm, and therefore has a higher impurity content than Models 1 and 2.

[0049] The vacuum distillation step for the unconverted oil (corresponding to the vacuum distillation step for the blended feedstock when the unconverted oil and the refined fraction are blended before this step) can be performed before the catalytic dewaxing step. Usually, the product obtained after catalytic dewaxing is distilled under reduced pressure to obtain a lubricating base oil having a desired boiling point by fractionation, but in the process of the present invention, the vacuum distillation is performed first, and only the fraction having the desired boiling point is introduced into the catalytic dewaxing step, so that only the product having the desired boiling point can be produced, and not only the production amount of the product can be adjusted, but also the operation cost of the process can be reduced by further reducing the process scale.

[0050] The vacuum distillation step for the unconverted oil can be carried out under the same process conditions as the vacuum distillation of the waste lubricating oil in the refined fraction production step, whereby the unconverted oil or blended feedstock is fractionated by boiling point.

[0051] The catalytic dewaxing selectively isomerizes the wax components contained in unconverted oil or blended stock to improve low temperature properties (ensuring a low pour point) and maintain a high viscosity index (VI). The present invention aims to improve efficiency and yield by improving the catalyst used in the catalytic dewaxing process. The catalytic dewaxing step includes a dewaxing reaction and a subsequent hydrofinishing reaction.

[0052] In general, the main reaction of catalytic dewaxing is to convert N-paraffins to isoparaffins for improving low-temperature properties through isomerization, and it has been reported that the catalysts used here are mainly bifunctional catalysts. Bifunctional catalysts are composed of two active components: a metal active component (Metal Site) for hydrogenation / dehydrogenation reactions and a support (Acid Site) having an acid site for skeletal isomerization via carbenium ions, and zeolite-structured catalysts are generally composed of an aluminosilicate support and one or more metals selected from Group 8 metals and Group 6 metals.

[0053] The dewaxing catalyst usable in the present invention comprises a support having an acid site selected from a molecular sieve, alumina and silica-alumina, and one or more metals having a hydrogenation function selected from elements of Groups 2, 6, 9 and 10 of the periodic table. Among the metals of Groups 9 and 10 (i.e., Group VIII), Co, Ni, Pt and Pd are preferred, and among the metals of Group 6 (i.e., Group VIB), Mo and W are preferred.

[0054] The types of carriers having acid sites include molecular sieves, alumina, silica-alumina, etc., among which molecular sieves refer to crystalline aluminosilicates (zeolites), SAPO, ALPO, etc., and medium pore molecular sieves (SAPO-11, SAPO-41, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, etc.) having 10-membered oxygen rings and large pore molecular sieves having 12-membered oxygen rings can be used.

[0055] In particular, in the present disclosure, it is preferable to use EU-2 zeolite with a controlled degree of phase transition as a carrier. If the synthesis conditions are changed after a pure zeolite is produced, or if the synthesis is continued for a certain period of time even if the hydrothermal synthesis conditions are the same, the synthesized zeolite crystals may gradually undergo a transition to a more stable phase. This phenomenon is called zeolite phase transformation, and it has been confirmed that the isomerization selectivity is improved according to the degree of the phase transformation of the zeolite, and that the catalytic dewaxing reaction using the zeolite can also exhibit excellent performance.

[0056] The lubricant base oil produced by the above process may be a high-grade lubricant base oil having a grade of Group III or higher in the above-mentioned API classification. More specifically, the lubricant base oil may have a viscosity index of 120 or more, preferably 120-140, 120-135, 120-130, 120-125, 125-140, 125-135, 125-130, 130-140, and 130-135, and a degree of 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, and 99% or more.

[0057] Furthermore, the lubricating base oil may contain almost no impurities, such as sulfur, nitrogen, and chlorine, each of which is 1 ppm or less.

[0058] The lubricant base oil may have a Saybolt color of 27 or more, as measured according to ASTM D156. If the Saybolt color value is 27 or more, the lubricant base oil is treated as having the stability of Water White grade. Water White grade lubricant base oils have sulfur and nitrogen contents of less than 1 ppm, a saturation level of 99% or more, and an aromatic content of less than 1%, and are more stable than typical API Group III lubricant base oils.

[0059] The lubricating base oil can exhibit a UV260-350nm absorbance of 2.5 or less and a UV325nm absorbance of 0.7 or less, measured according to ASTM D2008. Here, the absorbance at wavelengths of 260-350nm indicates that the lubricating base oil contains components having 3 or more aromatic rings, and the absorbance at wavelengths of 325nm indicates that the lubricating base oil contains components having 3-7 aromatic rings. Since the lubricating base oil has low absorbance at these wavelengths, it has a low aromatic content and thus has high stability.

[0060] Exemplary oil properties and impurity contents at each step of the process are shown in Table 2 below.

[0061] [Table 2]

[0062] Preferred examples are presented below to aid in understanding the present disclosure. However, the following examples are provided merely to facilitate understanding of the present disclosure, and the present disclosure is not limited thereto.

[0063] Working Example 1. Measurement of the properties and characteristics of the lubricating base oils produced by the process of the present invention Waste lubricating oil having a sulfur content of about 2000 ppm, a nitrogen content of about 1500 ppm, and a chlorine content of about 1500 ppm was centrifuged at a speed of about 300 rpm, and this was subjected to atmospheric distillation and first and second vacuum distillation to obtain a refined fraction. The obtained refined fraction was solvent extracted, and blended with unconverted oil as in the above-mentioned Model 1 in a blending amount of 2.3% based on volume, and then subjected to vacuum distillation and catalytic dewaxing to obtain a lubricating base oil. Here, the atmospheric distillation was performed at a temperature of 50°C to 350°C and at atmospheric pressure. The process conditions of the first and second vacuum distillations are as shown in Tables 3 and 4 below.

[0064] [Table 3]

[0065] [Table 4]

[0066] The process conditions for the solvent extraction are as shown in Table 5 below.

[0067] [Table 5]

[0068] The catalytic dewaxing is carried out at a temperature of 300°C and a pressure of 150 kg / cm 2 The process was carried out under a pressure of 1000 psi and in the presence of a hydrogenation catalyst supported by EU-2 zeolite. The properties and various characteristics of the lubricant base oil produced by the process having the configuration of model 1 among the above processes were measured. As a result of the measurements, the lubricant base oil had a specific gravity of 0.84, a kinematic viscosity at 100°C of 7.3 cSt, a viscosity index (VI) of 129, and a kinematic viscosity at -33°C, and contained sulfur, nitrogen, and chlorine contents each less than 1 ppm, and contained almost no impurities except for unavoidable trace amounts. In addition to the above, the properties measured for the lubricant base oil are as shown in Table 6 below.

[0069] [Table 6]

[0070] The lubricant base oil was found to have a viscosity index of at least 120 and a saturation level of at least 95%, and thus met the criteria for Group III lubricant base oil in Table 1. The lubricant base oil had a bright and clear color when evaluated by the naked eye and exhibited a Saybolt Color of at least 27 as measured in accordance with ASTM D156. That is, the lubricant base oil is a lubricant base oil having a water white rating and has high thermal stability at high temperatures.

[0071] In addition, the lubricating base oil exhibits a low absorbance of up to 3.0 (up to 1.0 for a wavelength of 325 nm) measured in accordance with ASTM D2008 for UV having a wavelength of 260 to 350 nm, and particularly for UV having a wavelength of 325 nm, and therefore, it can be confirmed that the lubricating base oil has high stability against UV.

[0072] 2. Evaluation of lubricant base oil yield with and without blending waste lubricant refinery fraction A lubricating base oil was obtained under the same process conditions as in Example 1, except that the refined fraction of the waste lubricating oil was blended with the unconverted oil. The yield was compared with that of Example 1, and the results are shown in Table 7 below.

[0073] [Table 7]

[0074] As described above, when lubricant base oil is produced using a blending stock obtained by blending a waste lubricant refinery fraction with unconverted oil as a feedstock, the yield is equivalent to or slightly higher than that when only unconverted oil is used as a feedstock. This is thought to be due to the fact that unconverted oil contains about 15% N-paraffin, whereas refined fraction does not contain any wax components such as N-paraffin. In this way, when a certain amount of waste lubricant refinery fraction is blended with unconverted oil and used as a feedstock for lubricant base oil production, the stability and yield of the final product lubricant base oil can be increased.

Claims

1. A process for producing a lubricant base oil using a waste lubricant refinery fraction, comprising: refining the used lubricating oil to produce a refined fraction; pre-treating said refined fraction, wherein the pre-treated refined fraction contains less than 30 ppm nitrogen; and blending the pretreated refinery fraction with unconverted oil (UCO) prior to vacuum distillation and catalytic dewaxing, after vacuum distillation and catalytic dewaxing, or between vacuum distillation and catalytic dewaxing of the unconverted oil.

2. 2. The process for producing lubricant base oil using a waste lubricant refinery fraction according to claim 1, wherein the step of producing the refinery fraction comprises centrifuging the waste lubricant, distilling the waste lubricant at atmospheric pressure, distilling the waste lubricant at first and second reduced pressures, or a combination thereof.

3. The process for producing lubricant base oil using a waste lubricant refinery fraction according to claim 1 , wherein the pretreatment step of the refinery fraction comprises a step of solvent extraction of the refinery fraction.

4. The solvent used in the solvent extraction comprises N-methyl-2-pyrrolidone, sulfolane, DMSO, furfural, phenol, acetone, or a combination thereof. A process for producing a lubricating base oil using a waste lubricating oil refinery fraction according to claim 3.

5. The solvent extraction is carried out at a temperature of 50 to 150°C and at atmospheric pressure of 5 kg / cm ２ The process for producing a lubricating base oil using the waste lubricating oil refinery fraction according to claim 3, wherein the process is carried out under a pressure of 0.1 to 1000 MPa.

6. The process for producing lubricating base oil using waste lubricating oil refinery fraction according to claim 3, wherein the solvent extraction is carried out under a volume ratio of solvent to oil of 1:1 to 10:

1.

7. 2. The process for producing lubricant base oils utilizing waste lubricant refinery fractions according to claim 1, wherein the vacuum distillation is carried out prior to the catalytic dewaxing.

8. The process for producing lubricant base oils utilizing waste lubricant refinery fractions according to claim 1, wherein the catalytic dewaxing is carried out in the presence of a catalyst comprising an EU-2 zeolite carrier.

9. The process for producing lubricating base oil using a waste lubricating oil refinery fraction according to claim 1, wherein the blending amount of the refinery fraction relative to the unconverted oil is 1% to 10% by volume of the total blended raw material.

10. 2. A lubricating base oil produced by the process of claim 1, The lubricating base oil has a viscosity index of 120 or more and a degree of saturation of 90% or more.

11. 11. The lubricant base oil of claim 10, wherein the lubricant base oil has a saybolt color value of 27 or greater.

12. 11. The lubricant base oil of claim 10, wherein the lubricant base oil has a saturation level of 99% or greater.

13. 11. The lubricant base oil of claim 10, wherein the lubricant base oil has a sulfur, nitrogen, and chlorine content of less than 1 ppm each.

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