Patent Application
20250026996
The present application claims priority to Korean Patent Application No. 10-2023-0093263, filed on Jul. 18, 2023, the entire contents of which are incorporated herein for all purposes by this reference.
Embodiments of the present disclosure relate to a method of recycling waste lubricant.
Waste lubricant may undergo a series of refining processes to obtain refined oil. The entire amount of the refined oil may be used as fuel oil in Korea. However, in overseas countries, only a portion of the refined oil is typically used as fuel oil, and the remainder is used as low-grade regenerated base oil.
On the other hand, good lube base oils have a high viscosity index, high stability (resistant to oxidation, heat, UV, etc.), and low volatility. The American Petroleum Institute (API) classifies lube base oils according to their quality as shown in Table 1 below.
In the above classification, the quality of lube base oils increases from Group I to V, of which Group III lube base oils are generally produced by advanced hydrocracking reactions. Typically, unconverted oil, which is a heavy oil fraction that is not converted to fuel oil during a fuel oil hydrocracking process, is used as a feedstock for the production of Group III and higher lube base oils.
Embodiments of the present disclosure provide a method of recycling waste lubricant.
A method of recycling waste lubricant according to a first embodiment of the present disclosure includes: providing a waste lubricant-derived oil fraction (“WLDOF”); pretreating the waste lubricant-derived oil fraction; and hydrocracking the pretreated waste lubricant-derived oil fraction.
The waste lubricant-derived oil fraction may have a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of 0° C.
The pretreatment operation may include performing solvent extraction on the waste lubricant-derived oil fraction.
According to an embodiment, the method may further include a first blending operation of blending the waste lubricant-derived oil fraction with a hydrocarbon feedstock prior to the hydrocracking operation to produce a first formulation.
According to an embodiment, the first formulation may include 1% to 10% by volume of the waste lubricant-derived oil fraction with respect to the total volume.
According to an embodiment, the method may further include recovering a plurality of fractions including a first fraction and a second fraction, from the product of the hydrocracking operation.
According to an embodiment, the first fraction may have a boiling point in a boiling point range of fuel oil.
According to an embodiment, the boiling point of the second fraction may be higher than the boiling point of the first fraction.
According to an embodiment, the method may further include a second blending operation of blending the second fraction with a separate waste lubricant-derived oil fraction to produce a second formulation.
According to an embodiment, the amount of the separate waste lubricant-derived oil used in the second blending operation may be 3% to 50% by volume with respect to the volume of the second formulation.
According to an embodiment, the method may further include an operation of catalytically dewaxing the second formulation.
According to an embodiment, the method may further include an operation of hydrofinishing the catalytically dewaxed second formulation and an operation of recovering the product of the hydrofinishing operation as a lube base oil.
A method of recycling waste lubricant according to a second embodiment of the present disclosure comprise: providing a first waste lubricant-derived oil fraction; blending the waste lubricant-derived oil fraction with a hydrocarbon feedstock to produce a first formulation; pretreating the first formulation by subjecting the first formulation to a solvent extraction operation; hydrocracking the pretreated first formulation; recovering a first fraction and a second fraction from the hydrocracking operation; blending the second fraction with a second waste lubricant-derived oil fraction to produce a second formulation; catalytically dewaxing the second formulation, and hydrofinishing the dewaxed second formulation to produce a lube base oil.
According to an embodiment, the first waste lubricant-derived oil fraction has a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of −21° C. to 0° C.
According to an embodiment, the waste lubricant-derived oil fraction is a refined oil fraction from a process in which waste lubricant undergoes at least one of a centrifugal separation, atmospheric distillation, vacuum distillation, or any combination thereof, and wherein the refined oil fraction has a sulfur content of less than 200 ppm, a nitrogen content of less than 100 ppm, and a chlorine content of less than 2000 ppm.
According to embodiments of the present disclosure, since waste lubricant can be reclaimed into fuel oil and advanced lube base oils, the embodiments of the present disclosure have the advantage of being economically beneficial, and an advantage that waste lubricant can be utilized as a feedstock for producing products for various applications.
The above and other objectives, features, and advantages of the embodiments of the present disclosure will be more clearly understood from the following detailed description, but the embodiments are not limited thereto. In describing the embodiments of the present disclosure, when the detailed description of the relevant known technology is determined to unnecessarily obscure the gist of the present disclosure, the detailed description may be omitted.
According to a first embodiment of the present disclosure, there is provided a method of recycling waste lubricant, the method including providing a waste lubricant-derived oil fraction 10, pretreating the waste lubricant-derived oil fraction 20, and hydrocracking the pretreated waste lubricant-derived oil fraction 30. Recycling waste lubricant, in a broadest sense, means reclaiming waste lubricant as a feedstock for the manufacture of a usable oil, however, in the context of the present disclosure, it means reusing waste lubricant as a feedstock for the manufacture of fuel oils and lube base oils.
As used herein, the term “waste lubricant-derived oil fraction” refers to a used lubricant. In general, a used lubricant contains a lube base oil and various additives. The additives may include large amounts of impurities that are not suitable for use in a lube base oil. For this reason, the waste lubricant contains large amounts of impurities. For example, the used lubricant (WLDOF) may contain 200 to 3000 ppm of sulfur, 200 to 2000 ppm of nitrogen, 20 to 2000 ppm of chlorine, and other metallic impurities that may be introduced during lubrication.
The waste lubricant-derived oil fraction may have a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of −21° C. to 0° C. The waste lubricant-derived oil fraction may have a kinematic viscosity at 40° C. in a range of 20 to 60 cSt and a pour point of lower than 0° C. The waste lubricant-derived oil fraction may have a kinematic viscosity in a range of 25 to 50 cSt when measured at 40° C. and a pour point of −5° C. The waste lubricant-derived oil fraction may have a kinematic viscosity in a range of 26 to 40 cSt measured at 40° C. and a pour point in a range of −21° C. to −6° C.
In one embodiment, the waste lubricant-derived oil fraction may be a refined oil fraction. As used herein, the term “refined oil fraction” refers to an oil component resulting from a process in which waste lubricant undergoes centrifugal separation, atmospheric distillation, vacuum distillation, or any combination thereof. The refined oil fraction may have a reduced impurity content compared to the original waste lubricant. For example, the refined oil fraction may have a sulfur content of less than 200 ppm, a nitrogen content of less than 100 ppm, and a chlorine content of less than 2000 ppm.
The method includes an operation of pretreating the waste lubricant-derived oil fraction. The pretreatment refers to the operation of treating the waste lubricant-derived oil fraction prior to the hydrocracking process, to minimize the impact of impurities contained in the waste lubricant-derived oil fraction on the process and the catalyst.
In one embodiment, the pretreatment operation may include an operation of performing solvent extraction on the waste lubricant-derived oil fraction.
The solvent extraction of the waste lubricant-derived refined oil fraction is an operation of blending the refined oil fraction and a solvent in a blending tank, an operation of maintaining the mixture in a stationary state to reach phase separation, thereby obtaining a phase in which oil is a main component, and an operation of removing a phase containing a large amount of impurity. The solvent used for the solvent extraction may be a solvent having a higher affinity to impurities than the oil component in the waste lubricant-derived refined oil fraction. As the solvent, N-methyl-2-pyrrolidone (NMP), sulfolane, DMSO, furfural, phenol, and acetone may be commonly used. As the solvent, any solvent that has a high affinity to impurities and a low affinity to the waste lubricant-derived refined oil fraction so as to be phase-separated from the waste lubricant-derived refined oil fraction may be used. In addition, the solvent may exhibit a different volatility from the oil fraction in the subsequent solvent separation process.
The solvent extraction of the waste lubricant-derived refined oil fraction may be carried out at a temperature of about 30° C. to 200° C., or about 40° C. to 150° C., or about 60° C. to 100° C. The solvent extraction of the waste lubricant-derived refined oil fraction may be carried out at a pressure in a range of atmospheric pressure to 20 kg/cm2, or in a range of atmospheric pressure to 15 kg/cm2, or in a range of atmospheric pressure to 10 kg/cm2.
The volume ratio of a solvent used in the solvent extraction operation of the waste lubricant-derived refined oil fraction with respect to the oil component contained in the waste lubricant-derived oil fraction may be 1:1 to 10:1, or 2:1 to 8:1, or 2:1 to 7:1, or 2:1 to 6:1, or 2:1 to 5:1, or 3:1 to 8:1, or 3:1 to 7:1, or 3:1 to 6:1, or 4:1 to 8:1, or 4:1 to 7:1, or 5:1 to 8:1. The volume ratio of the solvent used in the solvent extraction operation of the refined oil fraction to the oil component contained in the refined oil fraction may be in a range of 1:1 to 1.5:1. The above volume ratio is preferable in terms of the balance between the level of impurity removal through the solvent extraction and the yield of the hydrocracking product produced from the pretreated waste lubricant-derived oil fraction.
After the solvent extraction operation, the waste lubricant-derived oil fraction may have a specific gravity of 0.8 to 0.9, a kinematic viscosity at 100° C. in a range of 4 to 6 cSt, a viscosity index of 110 to 130, a pour point of −18° C. to −3° C., 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 the solvent extraction, the waste lubricant-derived oil fraction may have improved characteristics, and a reduced impurity content. After the solvent extraction, the waste lubricant-derived oil fraction may exhibit a light brown color of about 2 to 4 according to the ASTM standards, and may have a reduced sediment content compared to the original refined oil fraction which has not yet undergone the solvent extraction.
The method includes hydrocracking the pretreated waste lubricant-derived oil fraction. The hydrocracking is an operation in which long-chain hydrocarbons in the pretreated waste lubricant-derived oils are broken down into shorter-chain hydrocarbons by a catalyzed hydrogenation reaction. For example, in the hydrocracking operation, the C30+ hydrocarbon chains contained in the pretreated waste lubricant-derived oil fraction can be broken down into chains having fewer carbons. The hydrocracking operation may be performed at a reaction pressure of about 25 to 320 atm, or about 80 to 250 atm, and at a temperature of about 200° C. to 500° C., or 250° C. to 400° C. The hydrocracking operation may be performed at a liquid hourly space velocity (LHSV) in a range of, for example, about 0.1 to 8 hr−1, or of about 0.5 to 5 hr−1.
In an embodiment, the method may further include a first blending operation of blending the waste lubricant-derived oil fraction with a hydrocarbon feedstock prior 40 to the hydrocracking operation to produce a first formulation. The first blending operation may be performed prior to the pretreatment operation, or between the pretreatment operation and the hydrocracking operation. In an embodiment, the first blending operation may be performed prior to the pretreatment operation. As used herein, the term “hydrocarbon feedstock” refers to any material that may be an input for a refining, conversion, or other industrial processes in which hydrocarbons are a major component. The hydrocarbon feedstock may be provided at a temperature above its pour point, so that the hydrocarbon feedstock may be in a liquid state. The hydrocarbon feedstock may contain a non-hydrocarbon component such as organic and inorganic materials containing heteroatoms (for example, S, N, O, P, and metals). Crude oil, refinery streams, chemical plant streams (for example, steam cracked tar), and recycling plant streams (for example, pyrolysis oil from tires or municipal solid waste) are non-limiting examples of the hydrocarbon feedstock. The hydrocarbon feedstock may be a feedstock fed to the hydrocracking operation for the generation of a fraction having a boiling point within the boiling point range of fuel oils. Referring to
In an embodiment, the first formulation may include 1% to 10% by volume of the waste lubricant-derived oil fraction with respect to the total volume thereof. When the amount of waste lubricant-derived oil that is blended with the hydrocarbon feedstock in the first blending operation is less than 1% by volume of the total volume of the first formulation, the proportion of the high-carbon waste lubricant-derived oils in the formulation may be relatively low, so that hydrocracking of the high-carbon waste lubricant-derived oil may not be easily performed. When the amount of the waste lubricant-derived oil fraction that is blended with the hydrocarbon feedstock in the first blending operation exceeds 10% with respect to the total volume of the first formulation, the feedstock introduced into the hydrocracking operation may contain a high proportion of heavy oils containing catalyst deactivating impurities, resulting in increases in hydrocracking temperature and pressure conditions, and consequently, a strain on the hydrocracking catalyst. The first formulation may include the waste lubricant-derived oil fraction in an amount of 2% to 9% by volume or, 4% to 8% by volume, with respect to the total volume thereof. The first formulation may include a hydrocarbon feedstock other than the waste lubricant-derived oil fraction.
According to an embodiment, the method may further include recovering a plurality of fractions including a first fraction and a second fraction from the product of the hydrocracking operation 60. The hydrocracked waste lubricant-derived oil, or the hydrocracked first formulation is separated into components according to boiling point by separation distillation. Specifically, the product of the hydrocracking operation is separated by fractional distillation in the order of lower boiling point fractions to higher boiling point fractions. The plurality of fractions thus separated includes at least first and second fractions having different boiling points, which are recovered and used for appropriate purposes.
In an embodiment, the first fraction may have a boiling point in a boiling point range of fuel oils. For example, fuel oils include liquefied petroleum gas (LPG), gasoline, kerosene, diesel, and heavy fuel oil that are in order of decreasing boiling point. The first fraction may correspond to a fraction having a boiling point within the range of boiling points of fuel oils as described above, and may be further separated as necessary to include a specific fraction of the fuel oil. In an embodiment, the first fraction may have a boiling point lower than 400° C.
In an embodiment, the second fraction may have a boiling point higher than the boiling point of the first fraction. For example, the second fraction may have a boiling point of 450° C. or higher. Aside from the fuel oil, which is the oil fraction cracked in the hydrocracking operation, the product of the hydrocracking operation may also include an uncracked oil fraction. “Unconverted oil” (UCO) refers to heavy oil that remains from the hydrocracking operation and which is not converted to fuel oil as described above. The unconverted oil (UCO) may have a higher boiling point than fuel oil. The unconverted oil may be separated from the first fraction having a boiling point in the boiling point range of the fuel oil upon fractional distillation, and may be recovered. The second fraction may be a fraction including unconverted oil and may have a higher boiling point than the first fraction described above. The second fraction including the unconverted oil as described above may be recovered and introduced into the process operations for the preparation of the lube base oil. In an embodiment, the second fraction may exhibit a high pour point of 30° C. to 45° C. due to the high wax content of the unconverted oil but may contain impurities such as sulfur and nitrogen in a low content of less than 10 ppm.
Referring to
In an embodiment, the amount of the separate waste lubricant-derived oil used in the second blending operation may be 3% to 50% by volume with respect to the volume of the second formulation. For example, the amount of the separate waste lubricant-derived oil fraction introduced into the second blending may be about 5% to 45%, or about 5% to 40%, or about 5% to 35%, or about 5% to 30%, or about 5% to 25%, or about 5% to 20%, or about 5% to 15%, or about 5% to 10%, or about 7% to 40%, or about 7% to 35%, or about 7% to 25%, or about 7% to 20%, or about 7% to 15%, or about 7% to 10% of the volume of the second formulation. The pretreated waste lubricant-derived oil fraction may contain almost no wax component. Therefore, as described above, the pour point of the pretreated waste lubricant-derived oil fraction may be as low as −18° C. to −3° C. When the pretreated waste lubricant-derived oil fraction is blended with the second formulation containing unconverted oil having a high pour point of about 42° C., the fluidity of the blended raw material may be increased, so that the raw material may be easily transported even at low temperatures. When the blending amount of the pretreated waste lubricant-derived oil fraction is lower than 3% by volume, the effect of increasing the fluidity may not be significant, so that the blended raw material may not be easily transported from one operation to another. When the blending amount of the pretreated waste lubricant-derived oil fraction exceeds 20% by volume, the blended raw material is not suitable as a raw material for producing a high-grade lube base oil due to impurities contained in the pretreated waste lubricant-derived oil fraction and a low viscosity index.
Referring to
In general, the main reaction of the catalytic dewaxing may convert N-paraffin to iso-paraffin through an isomerization reaction to improve low-temperature properties. The catalyst used may mainly be a bi-functional catalyst. A bi-functional catalyst is composed of two active components: a metal active component (metal site) for hydrogenation/dehydrogenation reaction and a carrier (acid site) for skeletal isomerization using carbynium ions. A catalyst having a zeolite structure is generally composed of an aluminosilicate carrier and at least one metal selected from Group 8 metals and Group 6 metals.
The dewaxing catalyst used in embodiments of the present disclosure includes a carrier having an acid site selected from molecular sieve, alumina, and silica-alumina, and one or more hydrogenating metals selected from elements of Groups 2, 6, 9 and 10 of the Periodic table. In particular, among the metals in Group 9 and Group 10 (i.e., Group VIII), Co, Ni, Pt, and Pd may be used, and among the metals in Group 6 (i.e., Group VIB), Mo and W may be used.
The types of carriers having acid sites include molecular sieves, alumina, silica-alumina, and the like. Among these, the molecular sieves refer to crystalline aluminosilicates (zeolite), SAPO, ALPO, and the like. A medium pore molecular sieve with a 10-membered oxygen ring, such as SAPO-11, SAPO-41, ZSM-11, ZSM-22, ZSM-23, ZSM-35, and ZSM-48 is used, and a large pore molecular sieve with a 12-membered oxygen ring may be used.
In particular, in the embodiments of the present disclosure, EU-2 zeolite having a controlled phase transition degree may be used as the carrier. After pure zeolite is generated, the synthesis conditions are likely to change, or the synthesized zeolite crystal is likely to gradually transition to a more stable phase if the synthesis continues over a predetermined period time. This phenomenon is referred to as phase transformation of zeolite. It was confirmed that isomerization selection performance was improved according to the degree of phase transformation of the zeolite, and excellent performance was also exhibited in the catalytic dewaxing reaction using the same.
In an embodiment, the method may further include an operation of hydrofinishing the catalytically dewaxed second formulation 90 and an operation of recovering the product of the hydrofinishing operation as a lube base oil. The hydrofinishing 90 is an operation of removing aromatics, olefins, and solvents from the blended raw material to improve the oxidative stability and UV stability of the second formulation. The catalytically dewaxed second formulation is hydrofinished in the presence of a hydrofinishing catalyst. The hydrofinishing catalyst has the function of saturating the unsaturated hydrocarbons contained in the catalytically dewaxed second formulation, thereby improving color and storage stability. In an embodiment, the hydrofinishing catalyst may be the same as the dewaxing catalyst described above. The products of the hydrofinishing operation may be separated according to their viscosity, and among the products, a lube base oil with the desired properties can be recovered.
Specifically, the lube base oil produced by the method described above may be a high-grade lube base oil in Group III or higher according to the API classification described above. More specifically, the lube base oil may have a viscosity index of 120 or more, or 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 the degree of saturation is 90% or more, or 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.
In addition, the lube base oil may contain almost no impurities since the content of each of the impurities such as sulfur, nitrogen, and chlorine is 1 ppm or less.
The lube base oil may have a Saybolt color value of 27 or greater, when measured by the ASTM D 156 method. When the lube base oil has a Saybolt color value of 27 or greater, it is considered that this lube base oil is a lube base oil having stability corresponding to Water White grade. Water White grade lube base oils have a sulfur content of less than 1 ppm, a nitrogen content of less than 1 ppm, a saturation degree of 99% or more, and an aromatic content of less than 1%. These lube base oils are more stable than conventional API Group III lube base oils.
The lube base oil may exhibit a UV 260-350 nm absorbance of 2.5 or less and a UV 325 nm absorbance of 0.7 or less, as measured by ASTM D 2008. Here, the absorbance at a wavelength of 260 to 350 nm indicates that the test material contains a component having 3 or more aromatic rings, and the absorbance at a wavelength of 325 nm indicates that the test material contains a component having 3 to 7 aromatic rings. The lube base oil exhibits a low absorbance at these wavelengths. That is, the lube base oil may have a low aromatic content, thereby having high stability.
Hereinafter, some examples are presented to aid in the understanding of the embodiments of the present disclosure. However, the following examples are provided only to facilitate easier understanding of the embodiments of the present disclosure, and the embodiments of the present disclosure are not limited thereto.
Measurement of behavior and properties of fuel oil and lube base oil produced according to an embodiment.
Waste lubricant 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, followed by atmospheric distillation and vacuum distillation, to obtain a refined oil fraction. The resulting refined oil fraction was hydrotreated and subjected to hydrocracking.
Subsequently, the hydrocracked refined oil fraction was introduced into fractional distillation to obtain fuel oil and unconverted oil with different boiling points.
Like the refined oil fraction, a separate waste lubricant-derived oil fraction having undergone atmospheric distillation and vacuum distillation was subjected to hydrotreatment, and the hydrotreated oil was blended with the unconverted oil in a volume ratio of 25 (separate waste lubricant-derived oil fraction):75 (unconverted oil), and the blended oil was subjected to vacuum distillation, catalytic dewaxing, and hydrofinishing to produce a lube 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 vacuum distillation are shown in Table 2 below.
Process conditions of the hydrotreatment are shown in Table 3 below.
In addition, the catalytic dewaxing is carried out at a temperature of 300° C. and a pressure of 150 kg/cm2, in the presence of a hydrogenation catalyst with EU-2 zeolite as a carrier. The lube base oil prepared by the above-described production processes was measured for various properties, and as a result of the measurements, the lube 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, a kinematic viscosity of −33° C., a sulfur content of less than 1 ppm, and a nitrogen content of less than 1 ppm, and contained almost no impurities except for unavoidable trace amounts of impurities. In addition to the properties described above, other properties of the lube base oil were measured, and the measurement results are shown in Table 4 below.
The lube base oil had a viscosity index of at least 120 and a saturation degree of at least 95%, indicating that the lube base oil satisfies the conditions required for Group III lube base oil shown in Table 1. The base oil had a bright and clean color when visually evaluated by eye. The color was a Saybolt color value of 27 or more, when measured according to ASTM D 156. That is, the lube base oil is a lube base oil having a water white grade, and the lube base oil has high thermal stability at high temperatures.
In addition, the lube base oil exhibits a low absorbance of up to 3.0 (up to 1.0 at a wavelength of 325 nm) when measured according to ASTM D 2008 for UV having a wavelength of 260 to 350 nm, and especially for UV having a wavelength of 325 nm. It was confirmed that the lube base oil had high stability against UV.
As described above, blending waste lubricant-derived oil with unconverted oil and using the blended oil as a feedstock for the production of lube base oil can increase the stability and yield of the final product lube base oil.
It is noted that although the invention has been described in reference to specific embodiments, the invention is not limited to the described embodiments, and that many variations, and modifications of the described embodiments as well as other embodiments may be envisioned by the skilled person in this art without departing from the scope of the invention. Furthermore, the embodiments may be combined to form additional embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0093263 | Jul 2023 | KR | national |
