Method for removing chlorine from pyrolysis oil

Abstract

The present invention relates to a method for removing chlorine from pyrolysis oil, comprising the steps of: introducing waste plastic raw materials containing polyvinyl chloride resin and additives containing metal carbonates and metal hydroxides into a reactor; raising the temperature of the reactor to a range of 420°C to 440°C to perform a pyrolysis reaction and obtaining crude pyrolysis oil; and introducing the crude pyrolysis oil into a column to separate and recover it into an upper discharge stream containing light oil, a side discharge stream containing medium oil, and a lower discharge stream containing heavy oil, respectively.

Description

Technology Field

[0001] The present application relates to a method for removing chlorine from pyrolysis oil, and more specifically, to a method for removing chlorine from pyrolysis oil using an additive during the pyrolysis of waste plastic raw materials containing polyvinyl chloride resin. Background Technology

[0002] The pyrolysis reaction of waste plastics containing polyvinylchloride (PVC) can be carried out by obtaining pyrolysis oil in the form of distillation during the reaction using cylinders, or by utilizing the characteristic of PVC that decomposition begins at low temperatures to first remove the waste PVC and then react it at the reaction temperature to obtain the pyrolysis oil. However, in such distillation methods, chlorine (Cl) may vaporize and be obtained along with the pyrolysis oil before the waste PVC reacts with additives to form salts after decomposition; consequently, a large amount of Cl may be present in the available oil fraction. Furthermore, when waste PVC is decomposed at low temperatures, insufficient decomposition may result in Cl remaining within the pyrolysis oil instead of being lost as a low-molecular-weight gas.

[0003] Generally, the pyrolysis of waste PVC is carried out in a two-stage process: first, it is decomposed at a relatively low temperature of 200 to 350°C using a screw reactor or an auger reactor, and then reacted again at a temperature of 400°C or higher. In the case of screw-type reactors, there are issues with the complexity of the process system due to difficulties in scaling up and heat transfer. Additionally, Cl gas lost as gas during pyrolysis can be removed using a scrubber; however, as the amount of generated Cl gas increases, the size and cost of the scrubber also increase.

[0004] Therefore, to simplify the process, it is necessary to develop a technology that can effectively remove Cl in a single step by minimizing the generation of Cl gas during the pyrolysis process. Prior art literature

[0005] Republic of Korea Published Patent No. 10-2023-0056352 The problem to be solved

[0006] The problem to be solved in this disclosure is to provide a method that maximizes the yield of effective oil fractions while removing chlorine from the pyrolysis oil in a single step using an additive during the pyrolysis of waste plastics containing polyvinyl chloride resin, in order to solve the problem mentioned in the technology forming the background of the invention.

[0007] However, the problems that this application aims 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. means of solving the problem

[0008] According to one embodiment of the present disclosure for solving the above problems, a method for removing chlorine from pyrolysis oil is provided, comprising the steps of: introducing a waste plastic raw material containing a polyvinyl chloride-based resin and an additive containing a metal carbonate and a metal hydroxide into a reactor; raising the temperature of the reactor to a range of 420°C to 440°C to perform a pyrolysis reaction and obtaining crude pyrolysis oil; and introducing the crude pyrolysis oil into a column to separate and recover it into an upper discharge stream containing a light oil fraction, a side discharge stream containing a medium oil fraction, and a lower discharge stream containing a heavy oil fraction, respectively. Effects of the invention

[0009] According to the method for removing chlorine from pyrolysis oil of the present disclosure, a method can be provided that maximizes the yield of effective oil fractions while removing chlorine from the pyrolysis oil in one step by using an additive comprising metal carbonates and metal hydroxides during the pyrolysis of waste plastic raw materials containing polyvinyl chloride-based resins.

[0010] More specifically, by controlling the above additive and pyrolysis temperature, the Cl gas generated during the pyrolysis process of waste plastic raw materials including PVC can be reacted in the form of salt to effectively reduce the generation of Cl gas, and accordingly, it is possible to minimize the size of the scrubber for removing Cl gas and reduce costs.

[0011] The effects obtainable from the present application are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below. Brief explanation of the drawing

[0012] FIG. 1 is a process diagram illustrating a chlorine removal process for pyrolysis oil according to one embodiment. Specific details for implementing the invention

[0013] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which this disclosure pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0014] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0015] 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.

[0016] 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.

[0017] The term “and / or” includes a combination of multiple related described components or any of the multiple related described components.

[0018] 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).

[0019] Additionally, terms such as 'front,' 'rear,' 'top,' 'bottom,' 'side,' 'left,' 'right,' 'top,' and 'bottom' used in this disclosure are defined based on the drawings, and the shape and location of each component are not limited by these terms.

[0020] 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.

[0021] When it is said that one 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.

[0022] 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.

[0023] Additionally, terms such as "about," "substantially," etc., as used in this disclosure 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 this disclosure.

[0024] As used in this disclosure, 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 selected from gas, liquid, and solid.

[0025] Unless otherwise specified, the term "upper" as used in this disclosure refers to a point at a height of 0% to 20% downward from the top of the device, and specifically may refer to the top (top of the tower). Additionally, the term "lower" refers to a point at a height of 80% to 100% downward from the top of the device, and specifically may refer to the bottom (bottom of the tower).

[0026] In the present disclosure, the term “C#”, where “#” is a positive integer, represents any hydrocarbon having # carbon atoms. For example, the term “C20” represents a hydrocarbon compound having 20 carbon atoms.

[0027] The term “pressure” as used in this disclosure refers to gauge pressure measured relative to atmospheric pressure.

[0028] In the present disclosure, “crude pyrolysis oil” is a pyrolysis product obtained by pyrolyzing waste plastic raw materials, and is a mixed oil comprising light oil (LO), middle oil (MO), and heavy oil (HO), i.e., unrefined pyrolysis oil.

[0030] A method for removing chlorine from pyrolysis oil according to the present invention comprises the steps of: introducing waste plastic raw material containing a polyvinyl chloride-based resin and an additive containing a metal carbonate and a metal hydroxide into a reactor; raising the temperature of the reactor to a range of 420°C to 440°C to perform a pyrolysis reaction and obtaining crude pyrolysis oil; and introducing the crude pyrolysis oil into a column to separate and recover it into an upper discharge stream containing light oil, a side discharge stream containing medium oil, and a lower discharge stream containing heavy oil, respectively.

[0031] Hereinafter, a method for removing chlorine from pyrolysis oil according to the present disclosure is described in detail step by step with reference to the drawings.

[0032] Figure 1 is a flowchart of a chlorine removal process for pyrolysis oil according to one embodiment.

[0033] Referring to FIG. 1, waste plastic raw material (1) and an additive (2) containing metal carbonate and metal hydroxide are introduced into a reactor (100).

[0034] The above waste plastic raw material (1) includes a polyvinyl chloride (PVC)-based resin. More specifically, the above waste plastic raw material (1) may include a synthetic resin selected from the group consisting of polyvinyl chloride-based resin, polyethylene (PE)-based resin, polypropylene (PP)-based resin, polystyrene (PS)-based resin, polyethylene terephthalate (PET)-based resin, polybutylene terephthalate (PBT)-based resin, and combinations thereof.

[0035] More specifically, the waste plastic raw material (1) may include a PVC recovery polymer obtained through a mechanical recycling process.

[0036] The above mechanical recycling process can be carried out by conventional methods in the industry and may include, for example, steps of collection, sorting, crushing, melting, secondary crushing, cooling, and packaging.

[0037] The additive (2) includes a metal carbonate and a metal hydroxide. In this case, the molar ratio of the metal carbonate and the metal hydroxide in the additive (2) may be 1:0.5 to 1:3, preferably 1:1 to 1:2. The molar ratio may be a ratio that allows for complete reaction when reacting the metal carbonate and the metal hydroxide.

[0038] Additionally, the metal carbonate may be selected from the group consisting of, for example, sodium carbonate (Na2CO3), calcium carbonate (CaCO3), potassium carbonate (K2CO3), CaNa2(CO3)2, and combinations thereof. The metal hydroxide may be selected from the group consisting of, for example, sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), and combinations thereof.

[0039] According to one embodiment, before introducing the additive (2) into the reactor (100), the metal carbonate and the metal hydroxide may be mixed and then introduced, and more specifically, the metal carbonate and the metal hydroxide may be physically mixed or chemically reacted.

[0040] In one embodiment, when the chemically reacted additive (2) is introduced into the reactor (100), the chlorine removal effect may be further enhanced by the reaction product generated by the chemical reaction. For example, when CaCO3, a metal carbonate, and NaOH, a metal hydroxide, are mixed and reacted, not only are Ca(OH)2 and Na2CO3 produced as reaction products, but CaNa2(CO3)2 is also produced, and some CaCO3 may remain as unreacted products. These three types of reaction products have excellent reactivity with chlorine, which can further improve the chlorine reduction rate in crude pyrolysis oil. At this time, it may be preferable for CaCO3 and NaOH to be mixed in a molar ratio that allows for complete reaction, for example, 1:2.

[0041] More specifically, the reaction between the metal carbonate and the metal hydroxide can be carried out at 150°C to 250°C, preferably 170°C to 230°C, and more preferably 190°C to 210°C. By satisfying the above reaction temperature range, the synthesis of the metal carbonate and the metal hydroxide can be carried out at a low temperature without a high-temperature calcination process.

[0042] Meanwhile, the reactor (100) may be, for example, a batch reactor. By pyrolyzing waste PVC within a closed reaction system at a high temperature, not only can it be sufficiently cracked, but chlorine and additives can also be sufficiently reacted, thereby improving the Cl reduction effect in the pyrolysis oil.

[0043] Referring to FIG. 1, the reactor (100) is heated to a predetermined temperature to perform a pyrolysis reaction and obtain crude pyrolysis oil (3).

[0044] According to one embodiment, the operating temperature of the reactor (100), i.e., the pyrolysis reaction temperature, is 420°C to 440°C or 430°C to 440°C, and the operating pressure may be 20 to 100 bar or 30 to 90 bar. If the pyrolysis reaction temperature is too low, the pyrolysis reaction is not performed sufficiently, resulting in a problem where the yield of light and middle fractions is low and the yield of low-value heavy fractions is high. If the pyrolysis reaction temperature is too high, chlorine vaporizes before reacting with the additive, increasing the amount of chlorine gas generated, and consequently, an additional process may be required to remove the chlorine gas. Furthermore, as the operating temperature of the reactor increases, the operating pressure also increases, which may lead to a change in the reactor material or an increase in operating costs in order to ensure the safety of reactor operation.

[0045] According to one embodiment, the heating rate of the reactor may be 5°C / min to 10°C / min or 5°C / min to 8°C / min. Additionally, considering the thermal decomposition reaction of the waste plastic raw material (1) and the chlorine reduction efficiency, the thermal decomposition reaction may be carried out for 0.5 to 3 hours or 1 to 1.5 hours based on the time after reaching the reaction temperature.

[0046] The above crude pyrolysis oil (3) is a pyrolysis product obtained by pyrolyzing waste plastic raw material (1), and is a mixed oil comprising a light fraction, a medium fraction, and a heavy fraction. Here, the light fraction may be a relatively low boiling point fraction, specifically a fraction having a boiling point of 20°C or higher and less than 210°C, for example, a C5 to C12 hydrocarbon; the medium fraction may be a relatively medium boiling point fraction, specifically a fraction having a boiling point of 210°C or higher and less than 360°C, for example, a C13 to C22 hydrocarbon; and the heavy fraction may be a relatively high boiling point fraction, specifically a fraction having a boiling point of 360°C or higher, for example, a C23 to C40 hydrocarbon.

[0047] Additionally, the crude pyrolysis oil (3) may further include non-condensable gas and residue. Here, the non-condensable gas is a component with a lower boiling point than the light oil fraction, and may be, for example, a C1 to C4 hydrocarbon. Additionally, the residue may include undigested material that has not been completely decomposed and salt formed by the reaction of the additive with chlorine.

[0048] Meanwhile, during the above pyrolysis reaction, the additive (2) may react with chlorine (Cl) contained in the waste plastic raw material (1) to form salt. Accordingly, the above crude pyrolysis oil (3) contains the salt, and the lower discharge stream of the column (200) to be described later may also contain the salt.

[0049] Referring to FIG. 1, the crude pyrolysis oil (3) is fed into a column (200) and separated into an upper discharge stream (4) containing light oil, a side discharge stream (5) containing middle oil, and a lower discharge stream (6) containing heavy oil, respectively, for recovery.

[0050] According to one embodiment, a purification process of the crude pyrolysis oil (3) may be performed in the column (200), and the purification process may be performed in a manner conventional in the field, such as distillation using a distillation tower, and there are no particular limitations. For example, the feed stream supplied to the column (200) includes crude pyrolysis oil obtained from the pyrolysis of waste plastic, and depending on the boiling point of the components contained in the crude pyrolysis oil, a stream containing light oil fractions may be discharged to the top of the column, a stream containing medium oil fractions may be discharged to the side of the column, and a stream containing heavy oil fractions may be discharged to the bottom of the column.

[0051] The column (200) may be, for example, a distillation column, and the number and size of the column (200) are not particularly limited and may be set based on theoretical stages derived from a distillation curve considering the composition of crude 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 column. For example, the column (200) may have a multi-stage structure of 10 to 50 stages. As the upper stages of the column are moved, the temperature is progressively lower, allowing hydrocarbon components with a relatively high boiling point to be separated in the lower stages and hydrocarbon components with a relatively low boiling point to be separated in the upper stages.

[0052] According to one embodiment, the upper discharge stream (4) of the column (200) comprises a light fraction (7) and a non-condensable gas (8), and the light fraction (7) and the non-condensable gas (8) can be separated through additional processes such as condensation. Here, the light fraction may be a relatively low-boiling point fraction, specifically a hydrocarbon having a boiling point of 20°C or higher and less than 210°C, and the non-condensable gas may be a component having a lower boiling point than the light fraction, for example, a C1 to C4 hydrocarbon, and may further include chlorine gas.

[0053] According to one embodiment, the side discharge stream (5) of the column (200) includes an intermediate fraction. Here, the intermediate fraction may be a fraction with a relatively intermediate boiling point, specifically a hydrocarbon having a boiling point of 210°C or higher and less than 360°C, and may be, for example, a C13 to C22 hydrocarbon.

[0054] According to one embodiment, the lower discharge stream (6) of the column (200) comprises a heavy oil fraction (9) and a residue (10), and the heavy oil fraction (9) and the residue (10) can be separated using a membrane filter or the like. Here, the heavy oil fraction (9) may be a relatively high boiling point oil fraction, specifically a hydrocarbon having a boiling point of 360°C or higher, for example, a C23 to C40 hydrocarbon, and the residue (10) may include undissolved material that is not completely decomposed by a thermal decomposition reaction and a salt formed by the reaction of an additive with chlorine.

[0055] Although the method for removing chlorine from pyrolysis oil 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 illustrated above, processes and devices not separately described and illustrated may be appropriately applied and utilized to implement the method for removing chlorine from pyrolysis oil according to the present disclosure.

[0057] 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.

[0058] [ Examples and Comparative example ]

[0059] Comparative example 1

[0060] 100 g of waste plastic raw material containing 1 wt% PVC, 59.4 wt% PE, and 39.6 wt% PP was introduced into a reactor, heated to 420°C at a heating rate of 6°C / min, and then subjected to a pyrolysis reaction for 1 hour to obtain crude pyrolysis oil.

[0061] The above crude pyrolysis oil was fed into a column to recover light oil through the column top discharge stream, recover medium oil through the column side discharge stream, and recover heavy oil (9) through the column bottom discharge stream.

[0063] Comparative example 2

[0064] Except for the fact that the pyrolysis reaction was carried out at 430°C, the same as in Comparative Example 1 was performed to separate and recover light oil, medium oil, and heavy oil.

[0066] Comparative example 3

[0067] Except for the fact that the pyrolysis reaction was carried out at 440°C, the same as in Comparative Example 1 was performed to separate and recover light oil, medium oil, and heavy oil.

[0069] Comparative example 4

[0070] 100 g of waste plastic raw material containing 1 wt% PVC, 59.4 wt% PE, and 39.6 wt% PP and 7 g of CaO additive were introduced into a reactor, heated to 430°C at a heating rate of 6°C / min, and then subjected to a pyrolysis reaction for 1 hour to obtain crude pyrolysis oil.

[0071] The above crude pyrolysis oil was fed into a column to recover light oil fractions through the column top discharge stream, medium oil fractions through the column side discharge stream, and heavy oil fractions through the column bottom discharge stream.

[0073] Comparative example 5

[0074] The light fraction, medium fraction, and heavy fraction were separated and recovered in the same manner as Comparative Example 4, except that 16.8 g of K2CO3 was used as an additive.

[0076] Comparative example 6

[0077] The light fraction, medium fraction, and heavy fraction were separated and recovered in the same manner as Comparative Example 4, except that 29.4 g of Ca(OH)2 was used as an additive.

[0079] Comparative example 7

[0080] The light fraction, medium fraction, and heavy fraction were separated and recovered in the same manner as Comparative Example 4, except that 12.9 g of Na2CO3 was used as an additive.

[0082] Table 1 below summarizes the pyrolysis reaction process conditions of the above comparative examples, the amount of Cl gas generated by the pyrolysis reaction and the Cl content in the crude pyrolysis oil, and the Cl content of each fraction after the purification of the crude pyrolysis oil, and Table 2 below summarizes the yield of each fraction after the purification of the crude pyrolysis oil.

[0083] Here, the Cl content in the above oil was analyzed using combustion ion chromatography.

[0084] Reaction temperature (°C) additives Cl gas (mg) Cl content (ppm) in crude pyrolysis oil LO Cl content (ppm) MO Cl content (ppm) Comparative Example 1 420 - 460 1,150 1,380 420 Comparative Example 2 430 - 484 950 1,150 400 Comparative Example 3 440 - 489 910 1,060 220 Comparative Example 4 430 CaO 326 2,590 52 29 Comparative Example 5 430 K2CO3 355 2,270 19 14 Comparative Example 6 430 Ca(OH)2 187 4,100 19 12 Comparative Example 7 430 Na2CO3 460 1,150 15 20

[0085] * waste plastic Raw material (PVC 1 wt% My total Cl content: 570 mg (5,700 ppm)

[0086] LO (%) MO (%) HO (%) gas (%) Residue (%) Comparative Example 1 10.3 26.1 57.5 5.8 0.4 Comparative Example 2 20.4 37.3 33.3 7.8 1.2 Comparative Example 3 29.4 44.7 12.4 13.5 0.0 Comparative Example 4 20.6 33.7 39.1 6.6 0.0 Comparative Example 5 15.9 34.7 43.3 6.0 0.0 Comparative Example 6 20.2 38.6 35.4 5.7 0.0 Comparative Example 7 18.6 37.1 38.6 5.6 0.0

[0087] Referring to Table 1 above, it was confirmed that when waste plastic raw materials containing low-concentration PVC and additives are fed together and pyrolyzed, the Cl content in the light and middle fractions can be reduced by more than 90% compared to when additives are not used.

[0088] More specifically, referring to Comparative Examples 1 to 3, the concentration of Cl in the crude pyrolysis oil decreased as the pyrolysis reaction temperature increased. In addition, as in Comparative Example 2, when the reaction was carried out at 430°C for 1 hour without using additives, it was confirmed that about 85% of Cl was lost in the form of gas.

[0089] In addition, among the comparative examples using a single additive, Comparative Example 6 using Ca(OH)2 had the highest Cl gas reduction rate and Cl reduction rate in the middle fraction, and Comparative Example 7 using Na2CO3 as a single additive had the highest Cl reduction rate in the light fraction.

[0090] Referring to Table 2 above, it can be seen that when the pyrolysis reaction temperature is low, the yield of light and middle fractions decreases, while the yield of low-value heavy fractions increases. In other words, while the yield of high-value light and middle fractions can be increased as the pyrolysis temperature increases, if the pyrolysis temperature becomes too high, the internal pressure of the reactor increases significantly, leading to increased operating costs for the reactor and an increase in the amount of Cl gas generated.

[0091] In addition, when the pyrolysis reaction temperature conditions were the same, the gas yield decreased slightly when the additive was used compared to Comparative Example 2, which did not use the additive. This confirms that the additive reacts with Cl gas during pyrolysis and then forms or adsorbs a salt.

[0092] However, due to the limitations of the Cl content measuring equipment, it was difficult to confirm differences in content of 15 to 20 ppm or less. Accordingly, it was found that in order to confirm the difference in Cl removal effects between the mixed additive and the single additive according to the present invention, it is necessary to confirm the Cl removal effect under high concentration Cl conditions.

[0093] Accordingly, experiments were conducted below using waste plastic raw materials containing 10 weight% of PVC.

[0095] Comparative example 8 and 9

[0096] The Cl reduction rate under high concentration Cl conditions was confirmed using Ca(OH)2 and Na2CO3, which had relatively superior Cl reduction rates among Comparative Examples 4 to 7 above, respectively.

[0097] Specifically, Comparative Example 8 introduced 60 g of waste plastic raw material containing 10 wt% PVC, 54 wt% PE, and 36 wt% PP, and 38 g of Ca(OH)2 as an additive into a reactor (100), heated to 430°C at a heating rate of 6°C / min, and then performed a pyrolysis reaction for 1 hour to obtain crude pyrolysis oil.

[0098] The above crude pyrolysis oil was fed into a column to recover light oil fractions through the column top discharge stream, medium oil fractions through the column side discharge stream, and heavy oil fractions through the column bottom discharge stream.

[0099] In addition, Comparative Example 9 was carried out in the same manner as Comparative Example 8, except that 5.1 g of Na2CO3 was used as an additive, and light oil, medium oil, and heavy oil were separated and recovered.

[0101] Examples 1

[0102] First, an additive (2) was prepared by mixing 1.9 g of Na2CO3 and 2.6 g of Ca(OH)2 so that the molar ratio was 1:1.

[0103] 60 g of waste plastic raw material (1) containing 10 wt% PVC, 54 wt% PE, and 36 wt% PP, and 4.5 g of the prepared additive (2) were introduced into a reactor (100), heated to 430°C at a heating rate of 6°C / min, and then subjected to a pyrolysis reaction for 1 hour to obtain crude pyrolysis oil (3).

[0104] The above crude pyrolysis oil (3) was introduced into a column (200) to recover light oil fraction (7) through the column upper discharge stream (4), recover medium oil fraction through the column side discharge stream (5), and recover heavy oil fraction (9) through the column lower discharge stream (6).

[0106] Examples 2

[0107] The light oil, medium oil, and heavy oil were separated and recovered in the same manner as in Example 1, except that 6.2 g of additive (2) was used, which is a mixture of 2.4 g of CaCO3 and 3.8 g of NaOH solution (50% w / w) so that the molar ratio is 1:2.

[0109] Examples 3

[0110] 2.4 g of CaCO3 and 1.9 g of NaOH solution (50% w / w) were mixed so that the molar ratio was 1:2, and then 4.3 g of additive (2) synthesized at 200°C was used, and the same procedure as in Example 1 was carried out to separate and recover light oil, medium oil, and heavy oil.

[0111] Meanwhile, when recovering the oil after the above reaction, some of the water (1.9 g) contained in the NaOH solution was recovered along with the oil, and this was removed by centrifugation.

[0112] In addition, the result (wt%) of XRD analysis of the additive (2) prepared in Example 3 above is as shown in Table 3 below.

[0113] Additive composition Phase Ratio (%) Ca(OH)2 35 CaCO3 1 Na2CO3·H2O 55 CaNa2(CO3)2·H2O 5 etc 4

[0115] Comparative Examples 8 and 9 and Examples 1 to 3 above are cases in which waste plastic raw materials containing high-concentration PVC and additives were added together and then pyrolyzed. Table 4 below summarizes the types of additives used in each comparative example and example, as well as the Cl content of the light and middle fractions.

[0116] additives Cl content in LO (ppm) Cl content in MO (ppm) type situation Comparative Example 8 Ca(OH)2 - 59 67 Comparative Example 9 Na2CO3 - 41 143 Example 1 Na2CO3 + Ca(OH)2 1:1 molar ratio mixture 40 108 Example 2 CaCO3 + NaOH 1:2 molar ratio mixture 41 110 Example 3 CaCO3 + NaOH React at 200℃ after mixing in a molar ratio of 1:2 33 80

[0117] * waste plastic Raw material (PVC 10 wt% Total Cl content: 3,400 mg (57, 000 ppm )

[0119] Referring to Table 4 above, it was confirmed that when using an additive mixed with metal carbonates and metal hydroxides, the reduction rate of Cl in high-value light and middle fractions was generally improved.

[0120] In particular, Example 3, which used an additive produced by chemically reacting CaCO3 and NaOH, showed the best effect in reducing Cl in high-value light fractions. This is believed to be because reaction products such as Ca(OH)2, Na2CO3, and CaNa2(CO3)2, generated by the reaction of CaCO3 and NaOH as shown in Table 3 above, further reduced Cl in the light fractions.

[0121] In detail, Example 1 above used an additive that was physically mixed with Na2CO3 and Ca(OH)2, and compared to Comparative Example 8, which used only Ca(OH)2, the Cl content in the light fraction with the highest value was reduced. In addition, compared to Comparative Example 9, which used only Na2CO3 and had the highest Cl reduction rate for the light fraction among the additives, Example 1 had a similar level of Cl content in the light fraction, but the Cl content in the middle fraction was further reduced.

[0122] Example 2 above is a case where an additive obtained by physically mixing CaCO3 and NaOH was used, and the Cl content in the light fraction, which has the highest value, was reduced compared to Comparative Example 8, which used only Ca(OH)2. In addition, compared to Comparative Example 9, which used only Na2CO3 and had the highest Cl reduction rate for the light fraction among the additives, the Cl content in Example 2 was at a similar level, but the Cl content in the middle fraction was further reduced. This is expected to be because some of the additives reacted during the pyrolysis process even when CaCO3 and NaOH were physically mixed.

[0123] 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. Explanation of the symbols

[0124] 1: Waste plastic raw materials 2: Additives 3: Crude pyrolysis oil 4: Column top discharge stream 5: Column side discharge stream (middle fraction) 6: Column bottom discharge stream 7: Light oil 8: Uncondensed gas 9: Heavy oil 10: Residue 100: Reactor 200: Column

Claims

Claim 1 A method for removing chlorine from pyrolysis oil, comprising: a step of introducing waste plastic raw material including a polyvinyl chloride-based resin and an additive including a metal carbonate and a metal hydroxide into a reactor; a step of raising the temperature of the reactor to a range of 420°C to 440°C to perform a pyrolysis reaction and obtaining crude pyrolysis oil; and a step of introducing the crude pyrolysis oil into a column to separate and recover it into an upper discharge stream containing a light oil fraction, a side discharge stream containing a medium oil fraction, and a lower discharge stream containing a heavy oil fraction, respectively. Claim 2 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the metal carbonate is selected from the group consisting of sodium carbonate (Na2CO3), calcium carbonate (CaCO3), potassium carbonate (K2CO3), CaNa2(CO3)2 and combinations thereof. Claim 3 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the metal hydroxide is selected from the group consisting of sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2) and combinations thereof. Claim 4 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the additive reacts with chlorine contained in the waste plastic raw material to form salt, and the lower discharge stream contains said salt. Claim 5 A method for removing chlorine from pyrolysis oil according to claim 1, further comprising mixing and reacting the metal carbonate and the metal hydroxide before introducing the additive into the reactor. Claim 6 A method for removing chlorine from pyrolysis oil according to claim 5, wherein the reaction between the metal carbonate and the metal hydroxide is carried out at 150°C to 250°C. Claim 7 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the waste plastic raw material further comprises a synthetic resin selected from the group consisting of polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and combinations thereof. Claim 8 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the light fraction is a hydrocarbon having a boiling point of 20°C or higher and less than 210°C, the middle fraction is a hydrocarbon having a boiling point of 210°C or higher and less than 360°C, and the heavy fraction is a hydrocarbon having a boiling point of 360°C or higher. Claim 9 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the operating temperature of the reactor is 430℃ to 440℃. Claim 10 A method for removing chlorine from pyrolysis oil according to claim 1, wherein the operating pressure of the reactor is 20 to 100 bar. Claim 11 A method for removing chlorine from pyrolysis oil, wherein the reactor is a batch reactor in claim 1.

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