Method for refining pyrolytic oil

Abstract

The invention provides a method for refining pyrolytic oil, which comprises the following steps of: supplying a waste plastic raw material to a pyrolysis reactor for pyrolysis, and upwards discharging a gaseous material flow generated by the pyrolysis; supplying an upper discharge stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream having a reduced heavy oil fraction content from the distillation column; and feeding the pyrolysis oil stream to an anion exchange resin column to contact the stream with an anion exchange resin and remove impurities contained in the pyrolysis oil stream.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0124333, filed on September 11, 2024, the entire contents of which are incorporated herein by reference as part of the specification. Technical Field

[0003] This invention relates to a method for refining pyrolysis oil, and more specifically, to a method for removing impurities contained in pyrolysis oil made from waste plastics. Background Technology

[0004] Waste plastics made from petroleum have low recyclability and are mostly disposed of as garbage. Because these wastes take a long time to decompose under natural conditions, they pollute the soil and cause serious environmental pollution.

[0005] As a method of recycling waste plastics, waste plastics are pyrolyzed to convert them into usable oil fractions, and the resulting oil fractions are called waste plastic pyrolysis oil.

[0006] However, compared with oil fractions produced from crude oil by conventional methods, pyrolysis oil obtained by pyrolysis of waste plastics has a higher content of impurities such as nitrogen (N), chlorine (Cl), and silicon (Si). Therefore, it cannot always be used directly as high-value-added fuels such as gasoline and diesel, and must undergo post-processing.

[0007] As an existing post-processing step, waste plastic pyrolysis oil is hydrogenated in the presence of a hydrogenation catalyst to remove chlorine, nitrogen, or other metallic impurities. However, this process generates excessive HCl due to the high chlorine content in the waste plastic pyrolysis oil. HCl can cause equipment corrosion, abnormal reactions, and product performance degradation. In particular, HCl reacts with nitrogen compounds to produce ammonium salts (NH4Cl), which leads to reactor corrosion and reduced durability, as well as various process problems such as pressure differentials, reactor blockage, and reduced process efficiency.

[0008] Meanwhile, waste plastic pyrolysis oil is a mixture of hydrocarbon oil fractions with various boiling points and molecular weight distributions. Because the composition and reactivity of impurities in the pyrolysis oil vary depending on the boiling point and molecular weight distribution of the hydrocarbon mixture, waste plastic pyrolysis oil cannot be directly used in the petrochemical industry or related fields. Instead, it undergoes high-value-added processes such as boiling point separation or light-weighting processes. Among the hydrocarbon oil fraction mixtures, olefins, especially light olefins such as ethylene and propylene, are widely used in the petrochemical industry.

[0009] To increase the added value of waste plastic pyrolysis oil, the ongoing light-grade process is hydrogenation decomposition. However, compared with crude oil, natural gas, and naphtha fractions, waste plastic pyrolysis oil contains too many impurities. Therefore, due to the impurities in the hydrogenation decomposition process, the reactivity is significantly reduced. Thus, in addition to the hydrogenation treatment process, a separate hydrogenation decomposition process is required, which also reduces the process efficiency.

[0010] Therefore, since pyrolysis oil containing many impurities has limitations in its use, in order to use pyrolysis oil as a petrochemical feedstock, the impurities in pyrolysis oil should be removed, and a technology is needed to remove the impurities in pyrolysis oil without using post-treatment processes such as hydrogenation or hydrogen decomposition. Summary of the Invention

[0011] Technical issues

[0012] In order to solve the problems mentioned in the background art, the object of the present invention is to provide a method for removing impurities from pyrolysis oil.

[0013] That is, the present invention removes heavy oil fractions from pyrolysis oil by distillation column, which allows for fluidity even at room temperature and atmospheric pressure, so that impurities in pyrolysis oil can be continuously removed by anion exchange resin column with a small amount of energy.

[0014] However, the purpose of this application is not limited to the above-mentioned purposes, and other purposes not mentioned can be clearly understood by those skilled in the art from the following description.

[0015] Technical solution

[0016] In one general aspect, a method for refining pyrolysis oil includes: feeding waste plastic raw material into a pyrolysis reactor for pyrolysis and discharging the gaseous stream generated by the pyrolysis upwards; supplying the upper discharge stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream having a reduced heavy oil fraction content from the distillation column; and supplying the pyrolysis oil stream to an anion exchange resin column so that the stream contacts the anion exchange resin and removes impurities contained in the pyrolysis oil stream.

[0017] Beneficial effects

[0018] According to the method for refining pyrolysis oil of the present invention, when using anion exchange resin to remove impurities from pyrolysis oil, pyrolysis oil with adjusted C20+ heavy oil fraction content can be added to the anion exchange resin column to continuously remove impurities at room temperature and atmospheric pressure. The impurity removal capability is excellent, and the manufacturing cost can be reduced by reducing energy consumption, thereby improving cost competitiveness.

[0019] The effects that can be obtained in this application are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of a method for refining pyrolysis oil according to an exemplary embodiment of the present invention.

[0021] Figure 2 This is a process flow diagram of the refining method for pyrolysis oil in a comparative example. Detailed Implementation

[0022] The terms and words used in the specification and claims of this invention should not be construed as having a general or dictionary meaning, but should be interpreted as having a meaning and concept consistent with the technical idea of ​​the invention, based on the principle that the inventors are able to properly define the concepts of the terms in order to best describe their own invention.

[0023] The meaning of “contains” or “includes” as used in this article refers to a specific feature, region, integer, step, action, element or component, and does not exclude the addition of other specific features, regions, integers, steps, actions, elements or components.

[0024] As used herein, the term "flow" can refer to the fluid flow in a process or to the fluid itself flowing in a pipe. Specifically, flow can refer to the fluid itself flowing in the pipes connecting each device and the fluid flow. Additionally, the fluid can include any one or more components of gas, liquid, and solid.

[0025] Unless otherwise stated, the term "upper part" as used herein refers to a point 0% to 20% of the height measured downwards from the top of the apparatus, and specifically may refer to the top (top of the column). Conversely, the term "lower part" refers to a point 80% to 100% of the height measured downwards from the top of the apparatus, and specifically may refer to the bottom (bottom of the column). Furthermore, the term "sidecut fraction" refers to the middle portion located on the side of the apparatus. That is, the component flowing out as a sidecut fraction can represent the component flowing out from the middle portion of several trays excluding the top and bottom of the apparatus.

[0026] In this invention, the term "C#", where "#" is a positive integer, represents all hydrocarbons having # carbon atoms. Therefore, the term "C20" represents a hydrocarbon compound having 20 carbon atoms. Furthermore, the term "C#-" represents all hydrocarbon molecules having # or fewer carbon atoms. Therefore, the term "C20-" represents a mixture of hydrocarbons having less than 20 carbon atoms. Furthermore, the term "C#+" represents all hydrocarbon molecules having # or more carbon atoms. Therefore, the term "C20+" represents a mixture of hydrocarbons having more than 20 carbon atoms.

[0027] Terms such as “first,” “second,” “first,” or “second” used in this application may be used only to distinguish the corresponding constituent element from other corresponding constituent elements, and the corresponding constituent element is not limited in any other respect (e.g., importance or order).

[0028] The term "pressure" as used in this application refers to gauge pressure measured based on atmospheric pressure.

[0029] Unless otherwise defined herein, all terms used herein (including technical and scientific terms) may have the meaning commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, unless explicitly or specifically defined otherwise, terms defined in common dictionaries will not be interpreted ideally or excessively.

[0030] The present disclosure will be described in more detail below with reference to the accompanying drawings in order to provide a better understanding of the invention.

[0031] According to the present invention, a method for refining pyrolysis oil includes: feeding waste plastic raw material into a pyrolysis reactor for pyrolysis and discharging the gaseous stream generated by pyrolysis upward; supplying the upper discharge stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream having a reduced heavy oil fraction content from the distillation column; and supplying the pyrolysis oil stream to an anion exchange resin column so that the stream contacts the anion exchange resin and removes impurities contained in the pyrolysis oil stream.

[0032] Figure 1 This is a process flow diagram of a method for refining pyrolysis oil according to an exemplary embodiment of the present invention. Figure 1 In this process, waste plastic raw materials are fed into pyrolysis reactor 10 for pyrolysis, and the gaseous stream generated by pyrolysis is discharged upwards. The upper discharge stream from pyrolysis reactor 10 is supplied to distillation column 20, and the pyrolysis oil stream with a reduced heavy oil fraction content is discharged from distillation column 20. The pyrolysis oil stream is then supplied to anion exchange resin 30, allowing it to contact with the anion exchange resin and remove impurities contained in the pyrolysis oil stream.

[0033] The following is for reference Figure 1 The method will be explained in detail step by step.

[0034] In an exemplary embodiment of the present invention, the waste plastic raw material may include natural polymers, synthetic polymers, or mixtures thereof, and as a synthetic polymer, it may include one or more thermoplastic resins selected from the group consisting of polyethylene (PE) and polypropylene (PP). Additionally, the thermoplastic resin may be blended with other types of resins such as polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). For example, based on the total amount of the waste plastic raw material, the waste plastic raw material may be a thermoplastic resin having a total content of more than 80% by weight of polyethylene (PE) and polypropylene (PP), and containing less than 20% by weight of any one or more of PET and PVC.

[0035] After collection and sorting, waste plastics of this material can undergo pretreatment processes, including chopping, washing, drying, and melting. These pretreatment processes can be carried out using methods commonly found in the field.

[0036] For example, there are no particular restrictions on the size of the shredded waste plastics, which can range from 0.5 cm to 6.0 cm. The washed and dried shredded waste plastics are then added to a tubular melter such as an extruder for melting. The extruder has the functions of melting, mixing, and extruding, and can be, for example, a twin-screw extruder. When the waste plastics are thermoplastic resins such as polyethylene, polypropylene, or mixtures thereof, the melting temperature can be from 120°C to 350°C or from 150°C to 250°C, but is not limited to these.

[0037] In order to pyrolyze crushed or molten waste plastics used as raw materials for waste plastics, they can be fed into pyrolysis reactor 10.

[0038] In an exemplary embodiment of the present invention, the pyrolysis reactor 10 can be a stirred tank reactor with a stirrer. The stirrer is not particularly limited as long as it can sufficiently stir the waste plastic material supplied as raw material; for example, it can be a spiral ribbon type or an anchor type. Advantageously, it is kept at a distance of about 5 mm to 1 cm from the inner wall of the reactor to maximize the stirring of the waste plastic material and heat transfer through the reactor wall. Furthermore, the pyrolysis reactor 10 can be operated in a batch or continuous manner. In addition, nitrogen purging can be performed in the pyrolysis reactor to maintain an anaerobic or oxygen-deficient atmosphere during the pyrolysis reaction of the waste plastic material.

[0039] Waste plastic raw material is supplied to the pyrolysis reactor 10 equipped with a stirrer, and the waste plastic raw material is pyrolyzed while the stirrer is running.

[0040] Heating of waste plastic raw materials can be achieved by passing high-temperature / high-pressure steam, hot water, or heat transfer fluid through a jacket located outside the pyrolysis reactor to transfer high-temperature heat to the waste plastic raw materials, and there are no particular limitations on this.

[0041] The pyrolysis reactor 10 can stably and efficiently carry out pyrolysis in a non-oxidizing atmosphere, that is, in an atmosphere where waste plastics are not oxidized (burned).

[0042] The pyrolysis reactor 10 can operate at temperatures above 400°C and below 500°C. Specifically, the pyrolysis reactor 10 can operate at temperatures above 400°C and below 450°C. Furthermore, the pyrolysis reactor 10 can operate under pressures above atmospheric pressure. When the pyrolysis reactor 10 operates under these conditions, sufficient pyrolysis can be carried out at a adequate rate, and excessive generation of solid carbides such as coke due to high temperatures can be prevented.

[0043] When solid waste plastic is fed into the pyrolysis reactor 10 for pyrolysis, the C1 to C2 gaseous components, naphtha and other C5 to C12 light hydrocarbons and long-chain hydrocarbons in the waste plastic raw material are gasified and discharged from the pyrolysis reactor 10 as the upper discharge stream. The ungasified liquid components or high-viscosity residual wax such as coke are discharged to the lower part of the pyrolysis reactor 10.

[0044] The gaseous components produced by pyrolysis include a mixture of hydrocarbon oil fractions with various molecular weight distributions, including heavy oil fractions. Heavy oil fractions refer to hydrocarbon mixtures that are insoluble in water or have relatively high boiling points during the reaction or transportation process, such as high molecular weight C20+ wax components. However, this is just one example; the criteria for heavy oil fractions can vary depending on the separation and removal environment, such as the production or usage conditions of the pyrolysis oil. When recovering pyrolysis oil refined in an anion exchange resin column 30 while still containing heavy oil fractions, operational difficulties sometimes arise due to column blockage or transport challenges. Furthermore, the high heavy oil fraction content in the refined pyrolysis oil makes it difficult to achieve the high added value of waste plastic pyrolysis oil.

[0045] Therefore, in this invention, the upper discharge stream from the pyrolysis reactor 10 can be supplied to the distillation column 20 to separate the upper discharge stream from the pyrolysis reactor 10 by composition according to boiling point. Specifically, the stream containing C20+ heavy oil fraction can be separated and discharged to the lower part of the distillation column 20, the stream containing C1 to C4 gaseous components can be separated and discharged to the upper part of the distillation column 20, and the stream containing C4 to C25 middle oil fraction can be separated and discharged to the side-cut fraction of the distillation column 20. If necessary, the middle oil fraction can be separated and discharged into 1 to 3 side-cut fractions. Here, the stream containing the middle oil fraction can be supplied as pyrolysis oil stream to the anion exchange resin column 30.

[0046] The distillation column 20 can have a multi-plate structure with 10 to 50 plates, wherein the temperature gradually decreases as the number of plates increases, and hydrocarbon components with relatively high boiling points can be separated at the lower plates, hydrocarbon components with relatively low boiling points can be separated at the upper plates, and hydrocarbon components with relatively medium boiling points can be separated between those plates.

[0047] As needed, the vapor generated by heating in the distillation column 20 moves to the upper part of the column and is discharged. The discharged vapor can be partially or completely condensed in a condenser connected to the upper part of the column. A portion of the condensate can be recycled back into the column.

[0048] In the distillation column 20, heavy oil fraction, light oil fraction and middle oil fraction can be separated. The middle oil fraction is supplied as pyrolysis oil stream to the anion exchange resin column 30 to remove impurities. Thus, even under room temperature and atmospheric pressure conditions, the pyrolysis oil stream in the anion exchange resin of the anion exchange resin column 30 can have sufficient fluidity and can effectively remove impurities, thereby facilitating the use of refined pyrolysis oil.

[0049] The heavy oil fraction may have a C20+ content of 15% to 100% by weight, and the light oil fraction may have a C1 to C4 content of 50% to 100% by weight. Furthermore, based on the total amount of the middle oil fraction, the middle oil fraction may have a C1-C4 content of 0% to 10% by weight, 1% to 8% by weight, or 1% to 5% by weight, and a C20+ middle oil fraction content of less than 40% by weight, less than 30% by weight, 1% to 25% by weight, or 5% to 20% by weight. When the stream containing the middle oil fraction of the composition is supplied as a pyrolysis oil stream to the anion exchange resin column 30 to remove impurities, a separate heating device for maintaining flowability is not required, and the anion exchange resin column can operate with high removal performance. Furthermore, even if the middle oil fraction is not continuously supplied to the anion exchange resin column 30 in the distillation column 20, but is stored in a pyrolysis tank and then supplied to the anion exchange resin column 30, the anion exchange resin column can be operated without additional heating devices.

[0050] The distillation column can operate under both atmospheric and pressurized conditions. Specifically, distillation column 20 can operate at a pressure greater than 0 barg and less than 10 barg, or at a pressure greater than 0 barg and less than 5 barg. The operating temperature of the distillation column can be below 400°C to prevent additional pyrolysis. When distillation column 20 operates under these conditions, it can effectively separate heavy oil fractions, light oil fractions, and middle oil fractions, and can control the C20+ content in the middle oil fraction below the desired level.

[0051] The desired carbon range of the pyrolysis oil stream can be altered by adjusting the operating temperature of the upper part of the distillation column 20. Specifically, as the operating temperature of the upper part of the distillation column 20 increases, the carbon range of the pyrolysis oil can shift to a higher boiling point, and as the operating temperature of the upper part of the distillation column 20 decreases, the carbon range of the pyrolysis oil can shift to a lower boiling point. For example, by adjusting the operating temperature of the upper part of the distillation column 20 to the range of 30°C to 50°C, the middle oil fraction with the above-mentioned composition can be discharged as a side-cut fraction from the distillation column 20.

[0052] In an exemplary embodiment of the present invention, the pyrolysis oil stream is cooled to below 40°C by the heat exchanger 40, and the light oil fraction can be fully condensed and supplied to the anion exchange resin column 30. The type of heat exchanger 40 is not particularly limited; it can be a shell-and-tube type, a double-tube type, a plate type, etc., and refrigerants commonly used in chemical processes, such as cooling water or chilled water, can be used as the cooling refrigerant.

[0053] In an exemplary embodiment of the present invention, the anion exchange resin column 30 can operate at temperatures above 20°C, 20°C to 40°C, 20°C to 35°C, or 20°C to 30°C, and at pressures above 0 barg, 0 barg to 3 barg, 0 barg to 2 barg, or 0 barg to 1 barg. Even when the anion exchange resin column 30 operates under the above-mentioned operating conditions, the pyrolysis oil stream exhibits good fluidity and can effectively remove impurities from the pyrolysis oil stream while reducing energy consumption.

[0054] Meanwhile, when the pyrolysis oil stream contains a large amount of C20+ heavy oil fraction, in order to impart fluidity in the anion exchange resin column 30, the pyrolysis oil stream needs to be heated to a high temperature. However, in this case, a large amount of heating energy is consumed, and due to the characteristic that the adsorption equilibrium capacity decreases when the adsorption temperature of the anion exchange resin increases, it is difficult to effectively remove impurities in the pyrolysis oil stream at high temperatures.

[0055] The anion exchange resin filling the interior of the anion exchange resin column 30 can be a resin containing any one or more exchange groups selected from the group consisting of primary amine, secondary amine, tertiary amine, and quaternary ammonium groups. For example, the anion exchange resin can be one or more selected from styrene-based resins and acrylic resins, containing any one or more exchange groups selected from primary amine, secondary amine, tertiary amine, and quaternary ammonium groups.

[0056] As a specific example, the anion exchange resin can be a styrene-based resin containing a primary amine group as an exchange group. As a more specific example, the primary benzylamine can include, but is not limited to, benzylamine, 2-chlorobenzylamine, 3-chlorobenzylamine, 4-chlorobenzylamine, 2-fluorobenzylamine, 3-fluorobenzylamine, 4-fluorobenzylamine, 2,4-dichlorobenzylamine, 3,4-dichlorobenzylamine, 2,6-dichlorobenzylamine, 2,4-difluorobenzylamine, 3,4-difluorobenzylamine, 2,6-difluorobenzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 2,4-dimethylbenzylamine, 4-tert-butylbenzylamine, or 3-methoxybenzylamine.

[0057] As a specific example, anion exchange resin can be a styrene-based resin containing quaternary ammonium groups as exchange groups; as a more specific example, it can contain reactive groups in the form of hydroxides.

[0058] For example, the average particle size (D50) can be determined using laser diffraction or scanning electron microscopy (SEM). The average particle size (D50) is defined as the particle size at the 50% baseline of the particle size distribution (equivalent to 50% of the volumetric size of the particle size distribution).

[0059] The weight ratio of anion exchange resin in the anion exchange resin column 30 to pyrolysis oil with reduced heavy oil fraction content can be 1:1 or higher, 1:1 to 1:5, 1:1 to 1:4, 1:1 to 1:3, or 1:2 to 1:3. By maintaining the weight ratio of anion exchange resin in the anion exchange resin column 30 to pyrolysis oil within the above range, impurities in the pyrolysis oil stream can be effectively removed without excessively increasing costs.

[0060] Impurities may include one or more selected from the group consisting of chlorine (Cl), nitrogen (N), and silicon (Si). When refining pyrolysis oil by the method according to the invention, the chlorine content in the refined pyrolysis oil may be from 300 mg / kg to 950 mg / kg, 500 mg / kg to 900 mg / kg, or 600 mg / kg to 880 mg / kg. Additionally, the nitrogen content in the refined pyrolysis oil may be from 100 mg / kg to 3000 mg / kg, 200 mg / kg to 700 mg / kg, or 300 mg / kg to 600 mg / kg. Furthermore, the silicon content in the refined pyrolysis oil may be from 10 mg / kg to 400 mg / kg, 50 mg / kg to 400 mg / kg, or 100 mg / kg to 400 mg / kg.

[0061] Such refined pyrolysis oil can be used as a raw material for petrochemical processes, reducing greenhouse gas emissions caused by supply, improving process efficiency such as reducing energy consumption, and promoting a virtuous cycle of resources through waste plastic treatment.

[0062] The method for refining pyrolysis oil according to the present invention has been described and illustrated above in the accompanying drawings; however, the descriptions and illustrations in the drawings are only for understanding the core structure of the present invention, and there are no other separately described and illustrated methods and apparatuses that can be suitably applied and used to implement the method for refining pyrolysis oil according to the present invention, in addition to the methods and apparatuses described above and illustrated in the accompanying drawings.

[0063] The present invention will now be described in more detail through embodiments. However, while the following embodiments are provided to illustrate the invention, it will be apparent to those skilled in the art that various modifications and alterations can be made without departing from the scope and spirit of the invention, and the scope of the invention is not limited thereto.

[0064] Example

[0065] Example 1

[0066] Municipal solid waste containing PE and PP totaling 80% or more as waste plastic raw materials is fed into pyrolysis reactor 10 and pyrolyzed at 430°C to generate an upward-discharged gaseous stream. The upper discharge stream from pyrolysis reactor 10 is supplied to distillation column 20 and heated to 400°C to separate and discharge a stream containing C20+ heavy oil fractions, a stream containing C1 to C4 light oil fractions, and a stream containing C4 to C25 medium oil fractions.

[0067] A middle oil fraction stream containing a portion of the C20+ heavy oil fraction is passed through a heat exchanger 40 and cooled to below 40°C before being supplied to an anion exchange resin column 30. Here, the C20+ heavy oil fraction content in the middle oil fraction stream is determined to be 15% by weight.

[0068] The anion exchange resin column 30 uses styrene resin containing primary amine groups as the anion exchange resin and operates at a temperature of 20°C and a pressure of 0 barg. A middle oil fraction stream containing partially condensed C20+ heavy oil fraction is passed through the anion exchange resin to remove impurities. The weight ratio between the anion exchange resin and the middle oil fraction stream containing a portion of the C20+ heavy oil fraction is adjusted to 1:1.3.

[0069] Refined pyrolysis oil is obtained from a middle oil fraction stream containing a portion of the C20+ heavy oil fraction, which passes through an anion exchange resin.

[0070] Example 2

[0071] The refined pyrolysis oil was obtained in the same manner as in Example 1, except that a styrene resin containing a quaternary ammonium group in hydroxide form was used as the anion exchange resin.

[0072] Example 3

[0073] The refined pyrolysis oil was obtained in the same manner as in Example 1, except that the weight ratio between the anion exchange resin and the feed stream containing oil fractions from C4 to C25 was adjusted to 1:3.

[0074] Comparative example

[0075] Comparative Example 1

[0076] Figure 2 This is a process flow diagram of the refining method for the pyrolysis oil of Comparative Example 1.

[0077] Specifically, municipal solid waste comprising 80% by weight of PE and PP as waste plastic raw materials is fed into pyrolysis reactor 10 and pyrolyzed at 430°C. The waste is then cooled to below 40°C via heat exchanger 41 without separate separation. The oil fraction, excluding the stream containing uncondensed C1 to C4 light oil fractions, is fed into anion exchange resin column 31. Here, the C20+ heavy oil fraction content in the stream fed to the anion exchange resin column 31 is determined to be 49% by weight.

[0078] The anion exchange resin column 31 uses styrene resin with primary amines as functional groups and operates at a temperature of 20°C and a pressure of 0 barg. The top discharge stream from the pyrolysis reactor 11 is passed through the anion exchange resin to remove impurities. The weight ratio of the anion exchange resin in the anion exchange resin column to the top discharge stream from the pyrolysis reactor 11 is adjusted to 1:1.3.

[0079] In this situation, due to the high content of C20+ heavy oil fraction in the upper discharge stream of pyrolysis reactor 11, the resin and oil fractions cannot be well separated due to flowability issues, making operation difficult.

[0080] Comparative Example 2

[0081] Except that the anion exchange resin column 31 is operated at a temperature of 60°C and a pressure of 2 barg, refined pyrolysis oil is obtained from the top discharge stream from the pyrolysis reactor 11 through the anion exchange resin in the same manner as in Comparative Example 1.

[0082] Experimental Example

[0083] Experimental Example 1

[0084] The impurity content in the pyrolysis oil streams of Examples 1 to 3 and Comparative Examples 1 and 2 before and after treatment with anion exchange resin in anion exchange resin columns was determined, and the results are shown in Table 1 below.

[0085] [Table 1]

[0086] Referring to Table 1, it was confirmed that when refining pyrolysis oil using the methods of Examples 1 to 3, impurities contained in the pyrolysis oil stream are removed by supplying the pyrolysis oil stream containing a reduced heavy oil fraction content to the anion exchange resin column, thereby achieving fluidity and enabling the anion exchange resin column to operate under ambient temperature and pressure conditions. Therefore, energy consumption is reduced and the impurity removal capability is excellent.

[0087] In particular, it has been confirmed that by adjusting the weight ratio of the anion exchange resin to the feed stream containing oil fractions from C4 to C25 to 1:1 to 1:3, excessive cost increases are prevented, and the impurity removal capacity in the anion exchange resin column is better. Furthermore, when using styrene resin containing quaternary ammonium groups in the form of hydroxides as the anion exchange resin, the impurity removal capacity is better than that when using styrene resin containing primary amine groups.

[0088] However, in Comparative Example 1, the C20+ heavy oil fraction in the upper discharge stream of the pyrolysis reactor was high, and the anion exchange resin column was difficult to operate due to flowability issues, making it difficult to determine the impurity content after anion exchange resin treatment.

[0089] In addition, in Comparative Example 2, it was confirmed that the top discharge stream of the pyrolysis reactor with a high C20+ heavy oil fraction was given fluidity and allowed to operate, but the anion exchange resin column operated under high temperature and high pressure conditions, thus consuming a lot of energy and reducing the ability to remove impurities.

[0090] The exemplary embodiments of the present invention have been described above, but the present invention is not limited thereto. Those skilled in the art will understand that various changes and modifications can be made without departing from the concept and scope of the following claims.

[0091] [List of Reference Symbols]

[0092] 10, 11: Pyrolysis reactor

[0093] 20: Distillation column

[0094] 30, 31: Anion exchange resin columns

[0095] 40, 41: Heat exchangers

Claims

1. A method for refining pyrolysis oil, the method comprising: Waste plastic raw materials are fed into a pyrolysis reactor for pyrolysis, and the gaseous material generated by the pyrolysis is discharged upwards. The upper discharge stream from the pyrolysis reactor is supplied to the distillation column, and a pyrolysis oil stream with a reduced heavy oil fraction content is discharged from the distillation column. and The pyrolysis oil stream is supplied to an anion exchange resin column so that the stream comes into contact with the anion exchange resin and removes impurities contained in the pyrolysis oil stream.

2. The method for refining pyrolysis oil according to claim 1, wherein, The waste plastic raw material is a mixture containing one or more of polyethylene (PE) and polypropylene (PP).

3. The method for refining pyrolysis oil according to claim 1, wherein, The pyrolysis reactor operates at a temperature of 400°C to 500°C.

4. The method for refining pyrolysis oil according to claim 1, wherein, The upper part of the distillation column operates at a temperature of 30°C to 50°C.

5. The method for refining pyrolysis oil according to claim 1, wherein, In the distillation column, the upper discharge stream from the pyrolysis reactor is separated according to boiling point into a stream containing C20+ heavy oil fraction, a stream containing C1 to C4 light oil fraction, and a stream containing C4 to C25 medium oil fraction, and discharged accordingly. The pyrolysis oil stream is a feed stream containing the middle oil fraction.

6. The method for refining pyrolysis oil according to claim 1, wherein, The heavy oil fraction contained in the pyrolysis oil stream is less than 40% by weight.

7. The method for refining pyrolysis oil according to claim 1, wherein, The pyrolysis oil stream is cooled to below 40°C by a heat exchanger and then supplied to the anion exchange resin column.

8. The method for refining pyrolysis oil according to claim 1, wherein, The anion exchange resin column operates at a temperature above 20°C and a pressure above 0 barg.

9. The method for refining pyrolysis oil according to claim 1, wherein, The anion exchange resin filling the interior of the anion exchange resin column is a resin containing any one or more exchange groups selected from primary amine, secondary amine, tertiary amine and quaternary ammonium groups.

10. The method for refining pyrolysis oil according to claim 9, wherein, The anion exchange resin is selected from any one or more resins selected from styrene-based resins and acrylic-based resins.

11. The method for refining pyrolysis oil according to claim 1, wherein, The weight ratio of the anion exchange resin to the pyrolysis oil in the anion exchange resin column is 1:1 or higher.

12. The method for refining pyrolysis oil according to claim 1, wherein, The impurities include one or more selected from the group consisting of nitrogen (N), chlorine (Cl), and silicon (Si).

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