Method for refining pyrolysis oil

Abstract

The present invention relates to a method for refining pyrolysis oil, the method comprising: supplying pyrolysis oil comprising a silicon compound to a distillation column; discharging a liquid pyrolysis oil stream comprising the silicon compound through a side portion of the distillation column, and then reacting same with a basic solution, thereby producing a slurry comprising silicon; separating and removing the slurry from the liquid pyrolysis oil stream from which the slurry was produced, and refluxing the slurry-removed liquid pyrolysis oil stream to the distillation column; and discharging a gas-phase light oil through the top of the distillation column, and then condensing same, thereby obtaining a liquid-phase light oil.

Description

Pyrolysis oil refining method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0006134 dated January 15, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present application relates to a method for refining pyrolysis oil, and more specifically, to a method for removing silicon compounds from naphtha, which is an effective fraction obtained from pyrolysis oil.

[0005] With the recent increase in the development and use of plastics possessing properties required for various applications and purposes, the amount of plastic waste generated from various products is also gradually rising. Consequently, due to environmental pollution caused by plastic waste and the enormous disposal costs involved, methods for recycling waste plastics have become a significant social issue.

[0006] Waste plastic recycling methods can be broadly classified into mechanical recycling, chemical recycling, and thermal recycling. Among these, chemical recycling is attracting attention for its ability to reduce greenhouse gas emissions compared to waste plastic incineration and for enabling the development of alternative fuels.

[0007] Specifically, for the chemical recycling of waste plastics, a molten waste plastic is supplied to a reactor and pyrolyzed at a specific temperature, and the pyrolyzed product is supplied to a separation tower and subjected to a purification process for separation according to boiling point, thereby obtaining a light oil (LO) of C5 to C12 such as naphtha, a heavy oil (HO) with longer chains than this, and a residual oil (RO).

[0008] However, naphtha obtained from the pyrolysis oil produced by pyrolyzing waste plastics contains impurities such as silicon compounds. Therefore, a hydrogen reforming process is generally used to remove impurities from naphtha. However, the hydrogen reforming process has problems such as high investment costs and the need to use expensive hydrogen, so there was a need to develop a process that could reduce costs.

[0009] Accordingly, a method has been proposed to remove impurities from naphtha obtained from waste plastic pyrolysis oil by separating naphtha from crude pyrolysis oil and then reheating it to the reaction temperature to react it with caustic substances; however, this method has the problem of requiring separate energy consumption for impurity removal.

[0010] The problem to be solved in this disclosure is to provide a method for purifying pyrolysis oil that can remove silicon compounds, which are impurities in naphtha, by minimizing energy consumption in a process of recovering naphtha by distilling and purifying pyrolysis oil obtained by pyrolyzing waste plastics, in order to solve the problem mentioned in the background technology above.

[0011] However, the problems that this invention seeks to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0012] According to one embodiment of the present disclosure for solving the above problem, a method for purifying pyrolysis oil is provided, comprising the steps of: supplying pyrolysis oil containing a silicon compound to a distillation column; discharging a liquid pyrolysis oil stream containing the silicon compound to the side of the distillation column and reacting it with a basic solution to produce a silicon-containing slurry; separating and removing the slurry from the liquid pyrolysis oil stream from which the slurry was produced and recirculating the liquid pyrolysis oil stream from which the slurry was removed to the distillation column; and discharging a gaseous light oil fraction to the top of the distillation column and condensing it to obtain a liquid light oil fraction.

[0013] According to the pyrolysis oil refining method of the present disclosure, silicon compounds in naphtha can be removed by minimizing energy consumption during pyrolysis oil refining.

[0014] The effects obtainable from this invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which this disclosure pertains from the description below.

[0015] FIG. 1 is a process flow diagram of a pyrolysis oil purification method according to the present disclosure.

[0016] Terms and words used in the description and claims of this disclosure shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical idea of ​​this disclosure, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention.

[0017] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0018] The singular form of the noun corresponding to the item may include one or more of the said item unless the relevant context clearly indicates otherwise.

[0019] In the present disclosure, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0020] The term "and / or" includes a combination of multiple related described components or any of the multiple related described components.

[0021] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0022] In addition, terms such as 'front,' 'rear,' 'top,' 'bottom,' 'side,' 'left,' 'right,' 'top,' and 'bottom' used herein are defined based on the drawings, and the shape and location of each component are not limited by these terms.

[0023] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this disclosure, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0024] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0025] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0026] Additionally, terms such as "about," "substantially," etc., as used herein are used to mean at or near the numerical values ​​where inherent manufacturing and material tolerances are presented in the stated meanings, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content where precise or absolute numerical values ​​are mentioned to aid in understanding the present disclosure.

[0027] As used herein, the term 'stream' may refer to the flow of fluid within a process, and may also refer to the fluid itself flowing within the piping. Specifically, the stream may simultaneously refer to the fluid itself flowing within the piping connecting each device and the flow of the fluid. Additionally, the fluid may include one or more components among gas, liquid, and solid.

[0028] In the present disclosure, the term “C#”, where “#” is a positive integer, represents any hydrocarbon having # carbon atoms. For example, “C20” represents a hydrocarbon compound having 20 carbon atoms.

[0029] As used herein, “pressure” refers to gauge pressure measured relative to atmospheric pressure.

[0030] In addition, the term "boiling point" as used herein refers to the boiling point at atmospheric pressure.

[0031] Meanwhile, in the present disclosure, the operating temperature of the distillation column may refer to the temperature at the bottom of the apparatus unless otherwise specified. Likewise, the operating pressure of the distillation column may refer to the pressure at the top of the apparatus unless otherwise specified.

[0032] A method for purifying pyrolysis oil according to one embodiment of the present disclosure comprises: a step of supplying pyrolysis oil containing a silicon compound to a distillation column; a step of discharging a liquid pyrolysis oil stream containing the silicon compound to the side of the distillation column and reacting it with a basic solution to produce a silicon-containing slurry; a step of separating and removing the slurry from the liquid pyrolysis oil stream from which the slurry was produced and recirculating the liquid pyrolysis oil stream from which the slurry was removed to the distillation column; and a step of discharging a gaseous light oil fraction to the top of the distillation column and condensing it to obtain a liquid light oil fraction.

[0033] According to the present disclosure, when separating an effective fraction (a fraction with a boiling point of about 40°C to 200°C), i.e., naphtha, from crude pyrolysis oil obtained by pyrolyzing waste plastic, a method for refining pyrolysis oil can be provided in which a stream discharged to the side of a distillation column is reacted with a basic solution without changing temperature and pressure, and then refluxed back into the distillation column, thereby enabling the recovery of naphtha with reduced silicon content without using additional energy to heat to the reaction temperature.

[0034] Hereinafter, a method for refining pyrolysis oil according to the present disclosure is described in detail step by step with reference to the drawings.

[0035] FIG. 1 is a flowchart of a pyrolysis oil refining process according to one embodiment.

[0036] Referring to FIG. 1, pyrolysis oil (1) containing a silicon compound is supplied to a distillation tower (20).

[0037] At this time, the pyrolysis oil (1) containing the silicon compound may be obtained by pyrolyzing waste plastic raw materials, and the pyrolysis may be performed in a reactor (10).

[0038] Specifically, the waste plastic raw material may include natural polymers, synthetic polymers, or mixtures thereof, and the synthetic polymer may be selected from the group consisting of polyvinyl chloride (PVC) resin, polyethylene (PE) resin, polypropylene (PP) resin, polystyrene (PS) resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, and combinations thereof. In addition, the waste plastic raw material may contain impurities such as silicon (silicon-based compounds).

[0039] In addition, the waste plastic raw material may include silicon-containing additives, silicone resins, and / or compounds having siloxane bonds. When waste plastic containing elements other than carbon (C) and hydrogen (H) is fed into a pyrolysis process, impurities including sulfur (S), nitrogen (N), chlorine (Cl), silicon (Si), metals, etc. may be generated, and it is necessary to reduce such impurities for the utilization of pyrolysis oil. In particular, when a material containing silicon (Si) as described above is fed into the pyrolysis process described later, silicon compounds having siloxane bonds may be generated.

[0040] After being collected and sorted, waste plastic raw materials of this material may undergo a pretreatment process including crushing, washing, drying, and melting. The said pretreatment process may be carried out in a manner conventional in the field.

[0041] According to one embodiment, the pyrolysis reaction of the waste plastic raw material may be carried out at a temperature of about 400°C to 450°C, specifically about 420°C to 430°C, but is not limited thereto. Considering that the waste plastic is a thermoplastic resin, if the pyrolysis temperature is about 400°C or lower, the pyrolysis rate may be slow, and if it is about 450°C or higher, the pyrolysis rate may be fast, but due to the high heat, an excess amount of solid carbides such as char may be produced.

[0042] According to one embodiment, the pyrolysis oil (1) is a pyrolysis product obtained by pyrolyzing waste plastic raw materials, and may be a mixed oil comprising light oil (LO), middle oil (MO), and heavy oil (HO). Here, the light oil may be a C5 to C12 hydrocarbon, the middle oil may be a C13 to C22 hydrocarbon, and the heavy oil may be a C23 to C40 hydrocarbon. Specifically, the pyrolysis oil (1) is a non-condensing C1 to C4 It may include components; light components of C5 to C12 and medium and heavy components of C13 or higher that can be converted into liquid oil fractions by condensation; and high-boiling point residues that are not completely decomposed and therefore cannot be vaporized.

[0043] In addition, the light fraction may be a hydrocarbon component having a boiling point of about 40°C to 200°C, the medium fraction may be a hydrocarbon component having a boiling point of about 200°C to 350°C, and the heavy fraction may be a hydrocarbon component having a boiling point of about 350°C to 570°C.

[0044] In addition, the above pyrolysis oil (1) contains a silicon compound, and more specifically, the silicon compound may be a compound having a siloxane bond (Si-O-Si). For example, compounds having a siloxane bond may include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), or dodecamethylcyclohexasiloxane (D6), but are not limited thereto.

[0045] According to one embodiment, a purification process of the unrefined pyrolysis oil may be performed in the distillation column (20), and the purification process may be performed in a manner conventional in the art, without any particular limitations. For example, the feed stream supplied to the distillation column is unrefined pyrolysis oil obtained from the pyrolysis of waste plastic, and a stream containing light hydrocarbons with a low boiling point may be discharged from the top of the distillation column, and a stream containing medium and heavy hydrocarbons with a high boiling point may be discharged from the bottom of the distillation column.

[0046] The number and size of the distillation column (20) are not particularly limited and can be set based on theoretical stages derived from a distillation curve considering the composition of unrefined pyrolysis oil. Here, "theoretical stages" refers to a hypothetical region or number of stages in which two phases, such as gaseous and liquid phases, are in equilibrium with each other in the distillation column. For example, the distillation column (20) may have a multi-stage structure of 10 to 50 stages. As the upper stages of the distillation column are moved, the temperature is progressively lower, allowing hydrocarbon components with a relatively high boiling point to be separated in the stages located relatively lower, and hydrocarbon components with a relatively low boiling point to be separated in the stages located relatively higher.

[0047] Referring to FIG. 1, a liquid pyrolysis oil stream (2) containing the silicon compound can be discharged to the side of the distillation tower (20) and then reacted with a basic solution (A) to produce a slurry (4) containing silicon (Si).

[0048] At this time, the temperature of the liquid pyrolysis oil stream (2) discharged from the side of the distillation tower (20) may be about 40°C to 300°C, about 100°C to 300°C, or about 100°C to 250°C. Here, the temperature may be the same as the temperature of the stage at which the liquid pyrolysis oil stream (2) is discharged from the side of the distillation tower (20), and may be the same as the temperature at which the liquid pyrolysis oil stream (2) containing the silicon compound reacts with the basic solution (A). The higher the temperature of the side discharge stream, the higher the reaction temperature with the basic solution, and the silicon compound removal effect may be improved. However, if the temperature of the side discharge stream (2) is too high, the ratio of the middle oil and heavy oil in the side discharge stream increases, and consequently, silicon compounds in the middle oil and heavy oil are removed, so the final desired silicon compound removal effect in the light oil may be reduced.

[0049] Additionally, the reaction between the liquid pyrolysis oil stream (2) containing the silicon compound and the basic solution (A) can be carried out under a pressure of about 0 bar.g to 35 bar.g, preferably about 1 bar.g to 35 bar.g, more preferably about 10 bar.g to 35 bar.g. Specifically, the reaction pressure may refer to a pressure range in which the liquid pyrolysis oil stream (2) is pressurized by a pump for transporting the liquid pyrolysis oil stream (2) discharged to the side of the distillation tower (20). The higher the reaction pressure, the better the silicon compound removal effect may be.

[0050] By satisfying the above temperature and pressure ranges, when a basic solution (A) is introduced into the liquid pyrolysis oil stream (2) discharged from the side of the distillation tower (20) to react, a silicon compound can be reacted with the basic solution to produce a slurry (4) containing Si without using additional energy.

[0051] According to one embodiment, the liquid pyrolysis oil stream (2) containing the silicon compound may be discharged from the top of the distillation column at a stage greater than 0% and less than or equal to 50% of the theoretical stage, preferably between 2% and 30%, wherein the theoretical stage may be 1 to 50 stages. By satisfying the above range, the liquid pyrolysis oil stream (2) may have a temperature suitable for reaction with a basic solution (A) when discharged from the side of the distillation column. Within the distillation column, the temperature increases as the stage is located relatively lower, but the proportion of intermediate and heavy fractions with relatively high boiling points also increases. Therefore, the number of side discharge stages can be determined by considering the proportion of light fractions in the side discharge stream and the reaction temperature with the basic solution.

[0052] The above basic solution (A) reacts with a silicon compound contained in the pyrolysis oil to produce a slurry, and may be selected from the group consisting of, for example, sodium hydroxide (NaOH), potassium hydroxide (KOH), and combinations thereof.

[0053] At this time, the ratio of the mass flow rate of the basic solution (A) to the mass flow rate of the liquid pyrolysis oil stream (2) containing the silicon compound may be about 1:0.02 to 1:0.1, preferably about 1:0.02 to 1:0.05. When the above range of mass flow rate ratios is satisfied, the silicon compound removal efficiency can be further improved.

[0054] According to one embodiment, the liquid pyrolysis oil stream (2) discharged to the side of the distillation tower can be discharged and transported by a pump.

[0055] Referring to FIG. 1, the slurry (4) can be separated and removed from the liquid pyrolysis oil stream in which the slurry is generated, and the liquid pyrolysis oil stream (3) from which the slurry has been removed can be recirculated to the distillation tower (20).

[0056] According to one embodiment, the liquid pyrolysis oil stream in which the slurry is generated may be fed into a solid-liquid separation device (30), such as a decanter, to separate and remove the slurry (4) from the liquid pyrolysis oil stream (3). At this time, the solid-liquid separation may be performed at the same temperature and pressure as during the basic solution reaction.

[0057] Additionally, the liquid pyrolysis oil stream (3) from which the slurry has been removed may be recirculated to a stage above or the same stage as the stage from which the liquid pyrolysis oil stream (2) was discharged. Since the liquid pyrolysis oil stream (3) from which the slurry has been removed has a lower temperature than the liquid pyrolysis oil stream (2), if it is recirculated to a stage below the discharge stage, the operating efficiency of the distillation tower may be reduced.

[0058] Referring to FIG. 1, a gaseous light oil fraction (5) can be discharged from the top of the distillation tower (20) and then condensed to obtain a liquid light oil fraction (6). Here, the light oil fraction may refer to a hydrocarbon component having a boiling point of 40°C to 200°C.

[0059] Specifically, the upper discharge stream (5) of the distillation column comprises a hydrocarbon component having a boiling point of 200°C or lower, and more specifically, may comprise a light hydrocarbon component (6) having a boiling point of 40°C to 200°C and a hydrocarbon component (7) having a boiling point of less than 40°C.

[0060] The upper discharge stream (5) of the distillation tower is fed into a condenser (40) to perform a condensation process, so that light hydrocarbon components (6) having a boiling point of 40°C to 200°C are condensed and recovered as naphtha, and hydrocarbon components (7) having a boiling point of less than 40°C are uncondensed and discharged as gas, and if necessary, some of the condensate can be recirculated to the distillation tower (20).

[0061] Meanwhile, a liquid stream (8) containing a high-boiling point intermediate fraction and a heavy fraction can be discharged from the bottom of the distillation column. More specifically, the distillation column bottom discharge stream (8) may include hydrocarbon components with a boiling point exceeding 200°C, for example, intermediate hydrocarbon components having a boiling point between 200°C and less than 350°C and heavy hydrocarbon components having a boiling point between 350°C and 570°C.

[0062] Although the pyrolysis oil purification method according to the present disclosure has been described and illustrated in the drawings above, the description and drawings above describe and illustrate only the essential components for understanding the present disclosure. In addition to the processes and devices described and drawings above, processes and devices not separately described and illustrated may be appropriately applied and utilized to carry out the pyrolysis oil purification method according to the present disclosure.

[0063] The present disclosure will be explained in more detail below through examples. However, the following examples are intended to explain the present disclosure more specifically, and the scope of the present disclosure is not limited by the following examples.

[0064] [Example]

[0065] Example 1

[0066] According to the process flow diagram shown in Fig. 1, the pyrolysis oil (1) obtained by pyrolyzing waste plastic in the reactor (10) was supplied to the distillation tower (20) to perform a distillation purification process.

[0067] At this time, in the distillation column (20), a liquid pyrolysis oil stream (2) having a temperature of 170°C to 200°C and a pressure of 0 bar.g to 0.3 bar.g was discharged from the top of the distillation column to 20% of the theoretical number of stages using a pump, and an aqueous NaOH solution (A) with a concentration of 50 wt% was introduced into the liquid pyrolysis oil stream (2) to react. The reaction product was separated into solid and liquid in a decanter (30) to remove the slurry (4), and the liquid oil fraction (3) from which the slurry was removed was refluxed to the distillation column (20).

[0068] Meanwhile, after the gaseous fraction (5) was discharged from the top of the distillation tower, it was supplied to a condenser (40), and after undergoing a condensation process, naphtha (6) with reduced silicon compound content was obtained.

[0069] [Experimental Example]

[0070] Lab-scale experiments were conducted to determine the temperature range of the side discharge stream that is effective in removing silicon compounds from naphtha, which is the effective fraction. Specifically, using light pyrolysis oil obtained by pyrolyzing waste plastic, the Si content in the fraction was determined according to the reaction temperature with a basic solution and whether distillation occurred. Here, the reaction temperature with the basic solution corresponds to the temperature of the side discharge stream, and whether distillation occurs corresponds to the process in which the side discharge stream is refluxed to a distillation tower after reacting with the basic solution.

[0071] Experimental Example 1

[0072] 50 g of light pyrolysis oil obtained by pyrolyzing waste plastic was reacted with 2.5 g of an aqueous NaOH solution (concentration 50 wt%) at a temperature of 100°C and a pressure of 1.2 bar.g for 1 hour. The reaction mixture was allowed to stand to separate the oil layer, slurry, and water layer, after which the oil layer was recovered and distilled at 180°C. After condensing the oil vaporized by the distillation, the Si concentration in the oil was measured using ICP-OES.

[0073] Experimental Example 2

[0074] 50 g of light pyrolysis oil obtained by pyrolyzing waste plastic was reacted with 2.5 g of an aqueous NaOH solution (concentration 50 wt%) at a temperature of 250°C and a pressure of 32 bar.g for 1 hour. The reaction mixture was allowed to stand to separate the oil layer, slurry, and water layer, after which the oil layer was recovered and distilled at 180°C. After condensing the oil vaporized by the distillation, the Si concentration in the oil was measured using ICP-OES.

[0075] Comparative Experiment Example 1

[0076] The Si concentration in 50 g of light pyrolysis oil produced by pyrolyzing waste plastic was measured using ICP-OES.

[0077] Comparative Experiment Example 2

[0078] 2.5 g of an aqueous NaOH solution (concentration 50 wt%) was added to 50 g of light pyrolysis oil obtained by pyrolyzing waste plastic, and the mixture was reacted for 1 hour at a temperature of 20°C and atmospheric pressure. The reaction mixture was allowed to stand to separate the oil layer, slurry, and water layer, after which the Si concentration of the oil layer was measured by ICP-OES.

[0079] Comparative Experiment Example 3

[0080] 50 g of light pyrolysis oil obtained by pyrolyzing waste plastic was reacted with 2.5 g of an aqueous NaOH solution (concentration 50 wt%) at a temperature of 20°C and atmospheric pressure for 1 hour. The reaction mixture was allowed to stand to separate the oil layer, slurry, and water layer (approximately 5 wt% to 15 wt%), after which the oil layer was recovered and distilled at 180°C. After condensing the oil vaporized by the distillation, the Si concentration in the oil was measured using ICP-OES.

[0081] Table 1 below shows the Si concentration in the oil finally obtained in Experimental Examples 1 and 2 and Comparative Experimental Examples 1 and 3.

[0082] Reaction Temperature (°C) Reaction Pressure (bar.g) Distillation Status Si Concentration (ppm) Comparison Experiment Example 1 --X220 Comparison Experiment Example 2 200X210 Comparison Experiment Example 3 200O85 Experiment Example 1 1001.2O57 Experiment Example 2 25032O22

[0083] Referring to Table 1 above, the Si concentration was significantly reduced as the unrefined pyrolysis oil was distilled after reacting with a basic solution. In addition, the higher the reaction temperature between the pyrolysis oil and the basic solution, the better the effect of removing silicon compounds from the light fraction.

[0084] In particular, Experimental Examples 1 and 2 correspond to cases where a liquid pyrolysis oil stream is discharged at a temperature range of 100°C to 250°C in a distillation column and reacted with a basic solution, and it was confirmed that in this case, an excellent silicon compound removal effect can be achieved without additional heating.

[0085] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope and concept of the claims set forth below.

[0086] [Explanation of the symbol]

[0087] 10: Reactor

[0088] 20: Distillation tower

[0089] 30: High-liquid separator

[0090] 40: Condenser

Claims

1. A step of supplying pyrolysis oil containing silicon compounds to a distillation tower; A step of discharging a liquid pyrolysis oil stream containing the silicon compound to the side of the distillation tower and then reacting it with a basic solution to produce a silicon-containing slurry; A step of separating and removing the slurry from the liquid pyrolysis oil stream in which the slurry is generated, and recirculating the liquid pyrolysis oil stream from which the slurry has been removed to the distillation tower; and A method for refining pyrolysis oil comprising the step of discharging a gaseous light oil fraction from the top of the distillation tower and then condensing it to obtain a liquid light oil fraction.

2. In Paragraph 1, A method for refining pyrolysis oil, wherein the temperature of the liquid pyrolysis oil stream discharged from the side of the distillation tower is 100°C to 250°C.

3. In Paragraph 1, A method for purifying pyrolysis oil, wherein the above basic solution is selected from the group consisting of sodium hydroxide, potassium hydroxide, and combinations thereof.

4. In Paragraph 1, A method for refining pyrolysis oil, wherein the light fraction has a boiling point of 40°C to 200°C.

5. In Paragraph 1, A method for refining pyrolysis oil, wherein the pyrolysis oil containing the above silicon compound is obtained by pyrolyzing waste plastic raw materials.

6. In Paragraph 5, A method for purifying pyrolysis oil, wherein the above-mentioned waste plastic raw material is selected from the group consisting of polyvinyl chloride resin, polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and combinations thereof.

7. In Paragraph 1, The above pyrolysis oil is a mixed oil containing light fractions and heavy fractions, and The above light fraction is a C5 to C12 hydrocarbon, and The above heavy oil fraction is a C13 to C22 hydrocarbon, and A method for refining pyrolysis oil in which the above heavy oil fraction is a C23 to C40 hydrocarbon.

8. In Paragraph 7, A method for refining pyrolysis oil, comprising discharging a liquid stream containing an intermediate fraction and a heavy fraction to the bottom of the distillation tower.

9. In Paragraph 1, A method for refining pyrolysis oil, wherein the reaction between the liquid pyrolysis oil stream containing the silicon compound and the basic solution is carried out under a pressure of 0 bar.g to 35 bar.g.

10. In Paragraph 1, A method for refining pyrolysis oil, wherein the liquid pyrolysis oil stream containing the above silicon compound is discharged from the top of the distillation tower at a stage greater than 0% and less than or equal to 50% of the theoretical number of stages.

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