Method for producing waste plastic pyrolysis oil

Abstract

Provided is a technique whereby it is possible to stably produce a pyrolysis oil while preventing problems such as corrosion even when waste plastic having a high content ratio of a chlorine-containing resin is used as a raw material. The present invention provides a method for producing a waste plastic pyrolysis oil, the method being characterized by including performing pyrolysis of a waste plastic raw material containing a chlorine-containing resin to obtain a waste plastic pyrolysis oil, and by the nitrogen content in the waste plastic raw material being adjusted so that the pH of water used to wash the pyrolysis oil becomes higher than 5.0.

Description

Waste plastic pyrolysis oil manufacturing method

[0001] The present invention relates to a method for producing waste plastic pyrolysis oil.

[0002] In recent years, there has been a growing trend toward recycling waste plastics in order to protect the global environment and make effective use of resources. Recycling methods for waste plastics can be broadly divided into three categories: material recycling, which reuses plastics as raw materials for plastic products; chemical recycling, which reuses plastics as raw materials for chemical products; and thermal recycling, which recovers the heat generated when waste plastics are burned. Chemical recycling, which breaks down plastics and recycles them into various chemical substances, is expected to improve recycling rates. In particular, oil-recycling technology, which thermally decomposes waste plastics and recycles them into pyrolysis oil, has attracted attention as a highly efficient recycling method. The resulting pyrolysis oil can be refined and used as a raw material for various fuel oils and chemical products, or directly combusted for thermal recycling.

[0003] Olefin resins such as polyethylene (PE) and polypropylene (PP) are considered suitable waste plastics for use in the oil-to-energy process. However, waste plastics subjected to thermal decomposition are generally mixtures of many different resins. Therefore, a pretreatment process is usually carried out before the thermal decomposition process to separate and remove resins that are not suitable for the thermal decomposition process.

[0004] Among the resins that can be separated are chlorine-containing resins such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC). When chlorine-containing resins are fed to a thermal cracker, a portion of them is converted to inorganic chlorine, such as hydrogen chloride (HCl), or other acidic substances (acid gases), at temperatures between 400 and 600°C. This causes corrosion of the equipment and significantly hinders stable operation. Furthermore, pyrolysis oil obtained from waste plastics containing excessive amounts of chlorine components has a high chlorine concentration, and excessive HCl is generated during hydrotreatment in the pyrolysis oil refining process, causing problems such as corrosion of the equipment, abnormal reactions, and deterioration of product properties.

[0005] To address these issues, chlorine-containing resins are separated and removed in a pretreatment process prior to pyrolysis. However, it is extremely difficult to completely remove these chlorine-containing resins using this separation method in the pretreatment process. In particular, in the case of multilayer film, it is impossible to separate the chlorine-containing resins in the pretreatment process, and some of the chlorine-containing resin inevitably ends up in the pyrolysis equipment. To address this issue, various methods have been proposed, including using high-quality corrosion-resistant materials to prevent or avoid corrosion caused by acidic gases, adding alkaline substances such as hydrated lime or hot sand to waste plastics for pyrolysis (see, for example, Patent Documents 1 and 2), and washing (neutralizing) the pyrolysis oil with alkaline substances, such as sodium hydroxide (NaOH), in downstream processes prior to refining after pyrolysis. However, all of these methods increase construction and auxiliary material costs, thereby reducing the viability of waste plastic recycling.

[0006] JP 2023-021101 A JP 2001-107058 A

[0007] In this situation, there is a need for a technology that can prevent problems such as corrosion and enable stable production of pyrolysis oil, even when waste plastics containing chlorine-containing resins are used as raw materials.

[0008] The present invention includes, for example, the following embodiments. [1] A method for producing waste plastic pyrolysis oil, comprising pyrolyzing a waste plastic raw material containing a chlorine-containing resin to obtain the waste plastic pyrolysis oil, and adjusting the nitrogen content in the waste plastic raw material so that the pH of the water used to wash the pyrolysis oil is above 5.0. [2] The production method according to [1], in which the waste plastic pyrolysis oil is not neutralized and / or treated to decompose and remove chlorine-containing compounds after pyrolysis. [3] The production method according to [1] or [2], in which the nitrogen content in the waste plastic raw material is adjusted by (i) adding a nitrogen-containing substance and / or (ii) adjusting the content ratio of the nitrogen-containing substance in the waste plastic raw material to be subjected to pyrolysis. [4] The production method according to [3], in which the content ratio of the nitrogen-containing substance in the waste plastic raw material is adjusted by adjusting the constituent ratio of waste plastic obtained by separation from a waste plastic raw material mixture and / or adjusting the separation conditions of the waste plastic raw material mixture. [5] The manufacturing method according to [3] or [4], wherein the nitrogen-containing substance includes a nitrogen-containing compound and / or a nitrogen-containing resin, the nitrogen-containing compound being an amine, and the nitrogen-containing resin being at least one selected from the group consisting of polyamide resin, ABS resin, polyurethane resin, AS resin, urea resin, and melamine resin. [6] The manufacturing method according to any one of [3] to [5], wherein the nitrogen-containing substance is a substance that does not contain a nitrogen-oxygen bond. [7] The manufacturing method according to any one of [1] to [6], wherein the thermal decomposition comprises catalytic decomposition of the waste plastic raw material in the presence of an FCC catalyst at a temperature of 400°C or higher. [8] The manufacturing method according to [7], wherein the waste plastic raw material includes an alkaline earth metal-containing substance that reacts with the chlorine component contained in the waste plastic raw material. [9] The manufacturing method according to any one of [1] to [7], wherein a basic substance derived from the nitrogen component produced by the thermal decomposition of the waste plastic raw material reacts with the chlorine component contained in the waste plastic raw material, thereby causing the pH of the water used to wash the pyrolysis oil to exceed 5.0.

[10] The method according to any one of [1] to [9], wherein the waste plastic raw material contains at least one selected from polyethylene, polypropylene, and polystyrene, and the chlorine atom content in the waste plastic raw material is 0.1% by weight or more.

[11] A method for producing LPG, naphtha, or fuel oil, comprising mixing the waste plastic pyrolysis oil obtained by any one of [1] to

[10] with a petroleum fraction derived from crude oil, and treating the mixture in an oil refining step.

[12] The method according to

[11] , wherein the petroleum refining step includes at least one step of hydrorefining, hydrocracking, and catalytic cracking.

[0009] According to the present invention, even when waste plastics contain chlorine-containing resins, basic substances such as ammonia are produced from the nitrogen components contained in the waste plastics during the pyrolysis process, and these basic substances neutralize acidic corrosive substances such as hydrogen chloride produced from the chlorine components, thereby reducing or preventing problems such as corrosion. This not only makes it possible to stably produce pyrolysis oil, but also greatly relaxes restrictions on the weight of chlorine-containing substances in waste plastic raw materials, significantly improving the flexibility of waste plastic sources to be recycled.

[0010] 1 is a diagram showing the relationship between pH and corrosion rate for corrosion of carbon steel by an aqueous HCl solution at 57°C, as described in FIGURE 16-1 on page 176 of the Crude Unit Corrosion Guide 2016 by NACE International. 2 is a diagram showing an outline of a method for producing pyrolysis oil according to one embodiment of the present invention. 3 is a diagram showing an outline of the configuration of a pyrolysis apparatus used in the examples.

[0011] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments and can be implemented with any modifications within the scope of the present invention. The upper and lower limit values ​​of the numerical ranges described in this specification can be combined arbitrarily. For example, when "A to B" and "C to D" are described, the ranges "A to D" and "C to B" are also included as numerical ranges in the scope of the present invention. Furthermore, the numerical range "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value.

[0012] [Method for Producing Waste Plastic Pyrolysis Oil] One aspect of the present invention relates to a method for producing waste plastic pyrolysis oil containing a chlorine-containing resin. The production method includes pyrolyzing a waste plastic raw material containing a chlorine-containing resin to obtain waste plastic pyrolysis oil, and is characterized by adjusting the nitrogen content of the waste plastic raw material so that the pH of the water used to wash the pyrolysis oil exceeds 5.0. That is, the present invention is characterized in that the pH of the waste plastic pyrolysis oil is controlled to exceed 5.0 by adjusting the nitrogen content of the waste plastic supplied to the pyrolysis process.

[0013] (Waste Plastic Raw Materials) Examples of waste plastic raw materials include waste materials containing plastic as a main component, which are separated from general waste and industrial waste. Examples include waste materials containing thermoplastic resins as a main component, such as polyolefins such as polyethylene (PE) and polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and ABS (acrylonitrile butadiene styrene).

[0014] In particular, the waste plastic raw material preferably contains at least one selected from polyolefins such as PE and PP, and PS, in terms of producing little pyrolysis residue upon pyrolysis and not generating corrosive substances that could corrode equipment. In terms of suppressing coking, it is more preferable to contain at least one polyolefin such as PE and PP. In terms of ensuring flowability, it is even more preferable to contain PP. In some embodiments, the total content of polyolefins such as PE and PP (preferably PP) and PS in the waste plastic raw material is preferably 50% by weight or more, more preferably 75% by weight or more, and even more preferably 90% by weight or more, in terms of reducing residue. There is no particular upper limit to the total content of polyolefins such as PE and PP (preferably PP) and PS, but from the perspective of utilizing the waste plastic raw material as a chemically recycled raw material, the content of resins other than PE, PP, and PS is preferably 10% by weight or less, more preferably 5% by weight or less, and even more preferably 1% by weight or less. In some embodiments, the total content of polyolefins such as PE and PP (preferably PP) in the waste plastic raw material is preferably 50% by weight or more, more preferably 75% by weight or more, and even more preferably 90% by weight or more, in terms of reducing residue.

[0015] (Chlorine-containing resin) In the present invention, the waste plastic raw material contains a chlorine-containing resin. In the present invention, the nitrogen component contained in the waste plastic raw material neutralizes the chlorine component, thereby reducing or preventing problems such as corrosion, and therefore the restrictions on the weight of chlorine-containing substances in the waste plastic raw material are significantly relaxed, which can significantly improve the flexibility of waste plastic discharge sources that are the target of the waste plastic raw material.

[0016] In some embodiments, when the content of chlorine atoms in the waste plastic raw material is 0.1 wt% or more based on the total amount of the waste plastic raw material, the chlorine components can be neutralized with nitrogen components, and a decrease in the pH of the resulting pyrolysis oil can be suppressed. Furthermore, from the viewpoint of corrosion, the lower the content of chlorine atoms in the waste plastic raw material, the more preferable. The content of chlorine atoms in the waste plastic raw material can be measured by combustion ion chromatography (IC).

[0017] In some embodiments, the content of the chlorine-containing resin in the waste plastic raw material may be 0.1 wt % or more, or 0.5 wt % or more, based on the total amount of the waste plastic raw material. Within this range, the chlorine component contained in the chlorine-containing resin can be neutralized by the nitrogen component, and a decrease in the pH of the resulting pyrolysis oil can be suppressed.

[0018] The chlorine-containing resin is not particularly limited as long as it is a resin containing chlorine atoms in its structure, and examples thereof include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and chlorinated polyethylene (CPE).

[0019] (pH of pyrolysis oil) In this specification, the "pH of pyrolysis oil" is used synonymously with the "pH of water used to wash pyrolysis oil" and refers to the pH of water obtained by washing the oil produced in the pyrolysis step with an equal volume of water. The pH of the pyrolysis oil can be measured by the method described in the examples below.

[0020] If waste plastics contain chlorine-containing resins, a portion of the resins may be converted into inorganic chlorine, e.g., acidic substances (acid gases) such as hydrogen chloride (HCl), during the thermal decomposition process, potentially resulting in corrosion of the thermal decomposition equipment and impaired stable operation. Furthermore, the resulting pyrolysis oil also contains a high concentration of chlorine, which can generate excessive amounts of HCl during hydrotreating in the petroleum refining process after pyrolysis, resulting in equipment corrosion, reaction abnormalities, and deterioration of product properties. In particular, in atmospheric distillation units used in petroleum refining, it is known that carbon steel corrosion progresses significantly at pH levels of 5 or lower, and pH adjustment is an important factor in preventing corrosion. For example, as shown in the graph showing the relationship between pH and corrosion rate for carbon steel corrosion in aqueous HCl solution at 57°C in Reference 1 (Crude Unit Corrosion Guide 2016 by NACE International), it is confirmed that corrosion progresses rapidly at pH levels of 5 or lower. For this reason, when waste plastics contain chlorine-containing resins, methods have been taken such as removing as much chlorine as possible through separation before thermal decomposition, neutralizing the pyrolysis oil obtained by thermal decomposition with a neutralizing agent or the like before the oil refining process to adjust the pH to a target of 5.5 to 6.0 to suppress corrosion, decomposing and removing chlorine-containing compounds, or using high-quality corrosion-resistant materials.

[0021] In contrast, in the method of the present embodiment, the waste plastic raw material contains nitrogen-containing substances, which generate basic substances such as ammonia from the nitrogen components contained in the waste plastic raw material. These basic substances then neutralize with acidic corrosive substances such as hydrogen chloride generated from the chlorine-containing resin (chlorine component) contained in the waste plastic raw material, thereby increasing the pH of the pyrolysis oil (gas) and raising the pH of the water used to wash the pyrolysis oil to above 5.0. This prevents problems such as corrosion even when using waste plastic raw materials containing chlorine-containing resin, enabling stable production of pyrolysis oil. As a result, the use of high-quality corrosion-resistant materials and the downstream processes required for neutralizing the waste plastic pyrolysis oil and / or decomposing and removing chlorine-containing compounds can be omitted. In some embodiments, the neutralization and / or decomposition and removal of chlorine-containing compounds in the waste plastic pyrolysis oil are not performed after pyrolysis.

[0022] In some embodiments, the pH of the pyrolysis oil is preferably in the range of 5.5 to 13, more preferably in the range of 5.5 to 12.0, even more preferably in the range of 5.8 to 11.0, even more preferably in the range of 6.0 to 11.0, and particularly preferably in the range of 6.0 to 10.0. Having the pH of the pyrolysis oil within the above range can suppress corrosion caused by acidic substances such as chlorine. pH: If the pH of the pyrolysis oil exceeds 13.0, corrosion caused by alkaline substances progresses. In some embodiments, the pH of the pyrolysis oil is preferably 5.5 or higher, more preferably 5.8 or higher, and even more preferably 6.0 or higher. From the viewpoint of further suppressing corrosion caused by alkaline substances, the pH of the pyrolysis oil is preferably 13 or lower, preferably 12.0 or lower, even more preferably 11.0 or lower, and particularly preferably 10.0 or lower.

[0023] (Adjustment of Nitrogen Content) The method for adjusting the nitrogen content in the waste plastic raw material is not particularly limited, but is carried out, for example, by (i) adding a nitrogen-containing substance, and / or (ii) adjusting the content ratio of the nitrogen-containing substance in the waste plastic raw material to be subjected to pyrolysis. In some embodiments, the adjustment of the nitrogen content in the waste plastic raw material is carried out in a pretreatment (pretreatment step described below) before the pyrolysis step.

[0024] The content of nitrogen atoms in the waste plastic raw material is appropriately adjusted so that the pH of the pyrolysis oil falls within the above range, depending on the type of nitrogen-containing substance and the amount of chlorine components contained in the waste plastic raw material. In some embodiments, the content of nitrogen atoms in the waste plastic raw material is preferably 0.1 wt% or more, more preferably 0.3 wt% or more, based on the total amount of the waste plastic raw material. Within this range, the chlorine components contained in the chlorine-containing resin can be neutralized, and a decrease in the pH of the resulting pyrolysis oil can be suppressed. Furthermore, the content of nitrogen atoms in the waste plastic raw material is preferably an amount that results in an environment where the pH of the pyrolysis oil is less than 13, preferably 20 wt% or less, more preferably 10 wt% or less. The content of nitrogen atoms in the waste plastic raw material can be measured using CHN analysis.

[0025] In some embodiments, the content of nitrogen-containing substances in the waste plastic raw material is preferably 0.1 wt% or more, more preferably 0.3 wt% or more, and even more preferably 0.5 wt% or more, based on the total amount of the waste plastic raw material. Within this range, the chlorine components contained in the chlorine-containing resin can be neutralized, and a decrease in the pH of the resulting pyrolysis oil can be suppressed. Furthermore, the content of nitrogen-containing substances in the waste plastic raw material is preferably an amount that results in an environment where the pH of the pyrolysis oil is less than 13, and may be 50 wt% or less, 20 wt% or less, or 10 wt%.

[0026] In some embodiments, the weight ratio of the chlorine-containing resin to the nitrogen-containing substance in the waste plastic raw material is preferably in the range of 1:1 to 1:10, more preferably in the range of 1:1 to 1:8, and even more preferably in the range of 1:1 to 1:5. Within such a range, the chlorine components contained in the chlorine-containing resin are efficiently neutralized, and a decrease in the pH of the resulting pyrolysis oil can be suppressed.

[0027] In some embodiments, the nitrogen content of the waste plastic feedstock is adjusted by adding a nitrogen-containing substance. The nitrogen-containing substance is preferably added to the waste plastic feedstock before the pyrolysis step (e.g., in a pretreatment step) or during the pyrolysis step (preferably before the pyrolysis step) so as to have a neutralizing effect on acidic corrosive substances derived from chlorine components in the pyrolysis step.

[0028] A feedback process may be included to adjust the nitrogen content in the waste plastic raw material by measuring the pH of the pyrolysis oil during the pyrolysis process or in a small-scale pyrolysis process so that the pH of the pyrolysis oil is within the desired range, and then, based on the measurement results, (i) adding a nitrogen-containing substance and / or (ii) adjusting the content ratio of the nitrogen-containing substance in the waste plastic raw material to be subjected to pyrolysis (i.e., increasing the pH and decreasing the pH), as necessary. Alternatively, the nitrogen content and / or chlorine content in the waste plastic raw material may be measured before pyrolysis, and the nitrogen content in the waste plastic raw material may be adjusted by (i) adding a nitrogen-containing substance and / or (ii) adjusting the content ratio of the nitrogen-containing substance in the waste plastic raw material to be subjected to pyrolysis (i.e., increasing the pH and decreasing the pH), as necessary.

[0029] (Nitrogen-containing substance) The nitrogen-containing substance used to adjust the nitrogen content is a substance having nitrogen atoms, which is decomposed under pyrolysis conditions to produce NH ３There are no particular limitations on the nitrogen-containing substance as long as it generates an alkali that contributes to neutralization of the above. Examples of nitrogen-containing substances include low-molecular-weight compounds containing nitrogen atoms (nitrogen-containing compounds) and high-molecular-weight compounds containing nitrogen atoms (nitrogen-containing resins). In this specification, compounds with a molecular weight of 10,000 or less are referred to as low-molecular-weight compounds (nitrogen-containing compounds), and compounds with a molecular weight of more than 10,000 are referred to as high-molecular-weight compounds (nitrogen-containing resins).

[0030] Examples of the nitrogen-containing compound include amines, ammonium compounds, amide compounds, hydrazine or its derivatives, ureas, triazines, uracils, and cytosines.

[0031] Examples of amines include aliphatic amines (primary amines, aliphatic secondary amines, aliphatic tertiary amines), aromatic amines (aromatic primary amines, aromatic secondary amines, aromatic tertiary amines), hindered amines, etc. Examples of aliphatic amines include monoethanolamine, diethanolamine, ethylenediamine, diethylenetriamine, tetraethylenepentamine, aminoethylethanolamine, aminoethylpiperazine, diglycolamine, morpholine, dimethylethanolamine, methyldiethanolamine, monomethylethanolamine, aminopropylmorpholine, polyetheramine, etc. Examples of aromatic amines include o-toluidine, p-toluidine, p-phenylenediamine, aniline, 2,4,6-trimethylamine, anisidine, 3-(trifluoro)aniline, etc. Examples of hindered amines include poly C １－３ Alkylpiperidine or its derivative (bis(tri- to penta-C) such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate) １－３ Alkylpiperidyl) C ２－２０Examples of ammonium compounds include ammonium salts of oxygen acids such as ammonium phosphate. Examples of amide compounds include polycarboxylic acid amides such as malonamide and isophthalic acid diamide, and p-aminobenzamide. Examples of hydrazine or its derivatives include hydrazine, hydrazones such as acetone hydrazone and benzphenone hydrazone, and polycarboxylic acid hydrazides such as malondihydrazide. Examples of ureas include acyclic urea compounds (urea, methylenediurea, biuret, biurea, etc.), cyclic urea compounds (ethyleneurea, hydantoin, allantoin, uric acid, acetyleneurea, etc.), thiourea or its derivatives, etc. Examples of triazines include melamine compounds (e.g., melamine, 2-methylmelamine, guanylmelamine, melamine condensates (melam, melem, melon, etc.)), guanamine compounds (e.g., guanamine, methylguanamine, acetoguanamine, benzoguanamine, succinoguanamine, CTU-guanamine, etc.), salts of these triazines with (iso)cyanuric acid (e.g., melamine cyanuric acid), and salts of these triazines with oxyacids (e.g., melamine phosphate). Examples of uracils include uracil and uridine. Examples of cytosines include cytosine and cytidine. Among these, amines are preferred as the nitrogen-containing compound in terms of easy availability.

[0032] Nitrogen-containing compounds can be used alone or in combination. Many of these nitrogen-containing compounds are used as resin additives (e.g., antistatic agents). Nitrogen-containing compounds contained in waste plastic raw materials can be used, or new nitrogen-containing compounds can be added to waste plastic raw materials. Examples of nitrogen-containing compounds used as resin additives include neutralizers, antioxidants, metal deactivators, antistatic agents, antifogging agents, plasticizers, light stabilizers, flame retardants, lubricants, colorants, foaming agents, antiblocking agents, nucleating agents, processing aids, decomposing agents, and crosslinking agents.

[0033] Examples of the nitrogen-containing resin include polyamide resin, ABS (acrylonitrile butadiene styrene) resin, polyurethane resin, AS (acrylonitrile styrene) resin, urea resin, melamine resin, urea resin, thiourea resin, melamine-based resin, amino resin, aromatic amine-formaldehyde resin, polyesteramide, polyamideimide, polyacrylamide, polyaminothioether, etc. Examples of the polyamide resin include homo- or copolymer polyamides such as nylon 3, nylon 6, nylon 66, nylon 11, nylon 12, nylon MXD6, nylon 4-6, nylon 6-10, nylon 6-11, nylon 6-12, and nylon 6-66-610, and substituted polyamides having a methylol group or an alkoxymethyl group. Examples of melamine-based resins include homocondensation resins such as melamine resin (melamine-formaldehyde resin) and guanamine resin; and cocondensation resins such as urea-melamine resin, urea-benzoguanamine resin, phenol-melamine resin, benzoguanamine-melamine resin, and aromatic polyamine-melamine resin. Examples of aromatic amine-formaldehyde resins include aniline resins. Among these, polyamide resins are preferred as nitrogen-containing resins in terms of availability. The nitrogen-containing resins can be used alone or in combination.

[0034] In some embodiments, the nitrogen-containing substance includes a nitrogen-containing compound and / or a nitrogen-containing resin, the nitrogen-containing compound is an amine, and the nitrogen-containing resin is at least one selected from the group consisting of a polyamide resin, an ABS resin, a polyurethane resin, an AS resin, a urea resin, and a melamine resin.

[0035] In some embodiments, the nitrogen-containing substance is a substance that does not contain a nitrogen-oxygen bond. Substances that do not contain a nitrogen-oxygen bond can suppress the amount of nitrogen oxides (NOx) produced during the pyrolysis process. Because nitrogen oxides (NOx) can produce explosive NOx gum, a prior NOx treatment process is required to prevent this. Furthermore, because nitrogen oxides are believed to cause environmental problems such as air pollution, greenhouse effect, and ozone layer depletion, it is necessary to minimize the nitrogen content in the pyrolysis oil. Suppressing the amount of nitrogen oxides (NOx) produced not only eliminates the need for such an additional NOx treatment process, but also facilitates olefin recovery in existing ethylene units, which is preferable.

[0036] From the viewpoint of suppressing the amount of NOx generated, it is desirable that the nitrogen-containing substance does not contain a structure containing a nitrogen-oxygen bond in the molecule, as described above. However, if the light gas is not purified and recovered by a cryogenic purification process such as an ethylene unit, there is no particular problem even if the nitrogen-containing substance contains a structure containing a nitrogen-oxygen bond. Nitrogen-containing substances having a structure containing a nitrogen-oxygen bond include nitro compounds (e.g., nitrobenzene, mono- and dinitrotoluene, trinitrotoluene (TNT), tetryl, mononitrochlorobenzene, nitroaniline, nitrochlorotoluene, nitronaphthalene, dinitrophenol, picric acid (trinitrophenol), dinitrocresol, etc.); nitroso compounds (e.g., nitrosamines), N-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), N-nitrosodimethylamine (NDMA), N,N'-dinitrosopentamethylenetetramine (DPT), etc.).

[0037] As described above, from the viewpoint of suppressing the amount of NOx produced, it is desirable that the nitrogen-containing substance does not have a nitrogen-oxygen bond in the molecule. However, if the light gas is not purified and recovered by a cryogenic purification process such as an ethylene unit, there is no particular problem even if the nitrogen-oxygen bond is present.

[0038] (Alkaline earth metal-containing substance) In some embodiments, the waste plastic raw material may contain an alkaline earth metal-containing substance that reacts with the chlorine component contained in the waste plastic raw material. By containing such an alkaline earth metal-containing substance, acidic corrosive substances such as hydrogen chloride generated from the chlorine-containing resin (chlorine component) contained in the waste plastic raw material during the pyrolysis step can be neutralized, thereby further increasing the pH of the pyrolysis oil.

[0039] The alkaline earth metal-containing substance is not particularly limited as long as it can neutralize acidic corrosive substances such as hydrogen chloride. Examples include hydroxides, oxides, and carbonates of alkaline earth metals. Among these, hydroxides or oxides of alkaline earth metals are preferred, and hydroxides of alkaline earth metals are more preferred. Examples of alkaline earth metals include magnesium, calcium, strontium, barium, and radium. Magnesium reacts violently with water to generate hydrogen gas, which can cause fires. Barium is toxic. Radium is radioactive and therefore subject to radiation protection regulations. Therefore, calcium, magnesium, or barium is preferred in terms of ease of handling, and calcium is more preferred in terms of availability and price. In some embodiments, the alkaline earth metal-containing substance is selected from magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium oxide, calcium oxide, barium oxide, and strontium oxide. The alkaline earth metal-containing substance is more preferably selected from magnesium hydroxide, calcium hydroxide, and barium hydroxide, and even more preferably calcium hydroxide, calcium carbonate, or calcium oxide. Among these, calcium hydroxide is particularly preferred in terms of its "desalting effect."

[0040] The amount of alkaline earth metal-containing substance added is adjusted as appropriate depending on the type of plastic constituting the waste plastic raw material, the component ratio, the processing temperature, etc., but is preferably 0.01 to 4 parts by weight, more preferably 0.1 to 3.5 parts by weight, and even more preferably 0.5 to 3 parts by weight, per 100 parts by weight of the waste plastic raw material. An amount of 0.1 part by weight or more can exhibit the effect of neutralizing acidic corrosive substances. The greater the amount of alkaline earth metal-containing substance added, the higher the cost of auxiliary materials. Furthermore, adding too much alkaline earth metal-containing substance can increase the pH, leading to alkaline corrosion and potentially causing problems in terms of continuous operation. From this perspective, the smaller the amount of alkaline earth metal-containing substance added, the better. Adding 4 parts by weight or less is expected to be cost-effective and can suppress excessive increases in pH.

[0041] The alkaline earth metal-containing substance is preferably added to the waste plastic raw material before the pyrolysis process (e.g., after the separation process in the pretreatment process) or during the pyrolysis process so as to neutralize acidic corrosive substances derived from chlorine components in the pyrolysis process. In some embodiments, the method includes adding an alkaline earth metal-containing substance to the waste plastic raw material before the pyrolysis process. However, in the method of the present invention, the waste plastic raw material does not need to contain an alkaline earth metal-containing substance because the nitrogen components contained in the waste plastic can neutralize acidic corrosive substances. The present invention eliminates the need for a neutralization process, thereby reducing costs and reducing construction costs and the required site area, thereby providing excellent site location options. Furthermore, when an alkaline earth metal-containing substance is added in a process prior to the pyrolysis process, if there is a small amount or no acidic substance, the pH will increase, leading to alkaline corrosion, which may be detrimental to continuous operation.

[0042] (Other Components) In addition to the above, the waste plastic raw material may contain impurities such as thermosetting resin, FRP, paper, etc. Furthermore, examples of waste rubber include synthetic rubber waste such as waste tires, natural rubber waste, etc.

[0043] Examples of the shape of the waste plastic raw material include fluff, beads, flakes, chips, particles, powder, pellets, and the like.

[0044] (Production Method) Hereinafter, the production method of waste plastic pyrolysis oil of the present invention will be described with reference to the drawings.

[0045] 2 shows an example of a method for producing waste plastic pyrolysis oil according to one embodiment of the present invention. This production method includes pretreating a waste plastic raw material (a pretreatment step) and pyrolyzing the pretreated waste plastic raw material to obtain waste plastic pyrolysis oil (a pyrolysis step). If necessary, after the pyrolysis step, the waste plastic pyrolysis oil may be mixed with a petroleum fraction derived from crude oil and processed in an oil refining step.

[0046] (1) Pretreatment Process Since waste plastic raw materials are generally resin mixtures (waste plastic raw material mixtures) having various materials and shapes, if necessary, the waste plastic raw materials to be subjected to pyrolysis are crushed into shapes suitable for pyrolysis treatment, and / or the waste plastic raw materials are separated to separate resins and impurities that are not suitable for pyrolysis. In some embodiments, the pretreatment process includes at least one of a foreign matter removal process, a crushing process, and a separation process.

[0047] (Foreign Matter Removal Process) When waste plastic raw materials contain foreign matter such as metals or non-plastic materials, it is preferable to remove the foreign matter such as metals or non-plastic materials before the pyrolysis process. Foreign matter removal can be performed, for example, by removing metals by magnetic separation or by removing foreign matter such as other non-plastic materials by visual or manual sorting. Furthermore, since waste plastic raw materials generally have environmental substances such as dust and oil attached, the surface may be cleaned, if necessary, by a dry cleaning method using air blowing or a wet cleaning method using water, an organic solvent, or a surfactant before the pyrolysis process.

[0048] (Crushing step) From the viewpoint of improving the sorting efficiency, it is preferable to crush the waste plastic raw material to a size of preferably 5 to 50 mm, more preferably 10 to 40 mm, and even more preferably 15 to 25 mm in the longest diameter before the pyrolysis step. The crushing means is not particularly limited, and can be, for example, a single-shaft crusher, a double-shaft crusher, a crusher, or the like.

[0049] (Sorting Step) Before the thermal decomposition step, the waste plastic raw material is preferably subjected to at least one sorting process selected from, for example, an optical sorting step, an electrostatic separation step, and a specific gravity differential sorting step.

[0050] Optical fractionation is a method for sorting waste plastic raw materials based on differences in wavelength absorbance depending on the material. In some embodiments, when near-infrared light is irradiated onto waste plastic raw materials, the wavelength at which the absorbance peaks varies depending on the type of plastic. Taking advantage of this, near-infrared light of a specific wavelength is irradiated onto the waste plastic, and the type of plastic is identified based on the absorbance, and a sorting process is performed. In some embodiments, the type of plastic and additives contained in the plastic, such as flame retardants, are identified based on the Raman scattered light spectrum generated when a focused laser beam is irradiated onto the waste plastic raw materials, and a sorting process is performed.

[0051] Electrostatic separation is a method of separating plastics into those with a high charge and those without, utilizing the inherent charging properties of plastics. In some embodiments, electrostatic separation separates chlorine-containing plastics that have a high charge from those without.

[0052] Gravity differential sorting is a method of separating waste plastic raw materials based on differences in specific gravity between materials. In some embodiments, flotation sorting (gravity sorting using a liquid such as water) separates plastics with low specific gravity (floating matter), such as polyolefins (polypropylene, polyethylene, etc.), and plastics with high specific gravity (sediment), such as condensation synthetic films (polyester, nylon, etc.) with heavier specific gravities than polyolefins, chlorine-containing resins, and nitrogen-containing resins. Further separation can be performed by appropriately changing the specific gravity of the liquid used in flotation sorting, for example, by changing the blending ratio of water to organic solvent or salt, thereby separating plastics with different specific gravities. In some embodiments, plastics with different specific gravities are separated by centrifugation. Nitrogen-containing substances, such as nitrogen-containing resins, separated in this sorting process may be added to the waste plastic raw materials to adjust the nitrogen content.

[0053] In some embodiments, the content ratio of nitrogen-containing substances in the waste plastic raw material is adjusted in the separation process. For example, the content ratio of nitrogen-containing substances in the waste plastic raw material is adjusted by adjusting the constituent ratio of the waste plastic obtained by separation from the waste plastic raw material mixture and / or adjusting the separation conditions of the waste plastic raw material mixture.

[0054] In some embodiments, the content ratio of nitrogen-containing substances in the waste plastic raw material is adjusted by controlling the residual amount of nitrogen-containing resin by changing the pretreatment conditions of the waste plastic raw material. In a specific embodiment, the fractionation process includes an optical fractionation process and a specific gravity differential separation process, in which polystyrene is separated in the optical fractionation process, and the optical fractionation residue is separated into low-specific gravity plastics such as polyolefins such as polypropylene and polyethylene, and high-specific gravity plastics such as nitrogen-containing resins, and the content ratio of nitrogen-containing substances in the waste plastic raw material can be adjusted by adjusting the constituent ratios of the waste plastics obtained by this separation.

[0055] In another embodiment, the separation process includes a specific gravity differential separation process, and by adjusting the separation conditions (e.g., crushing particle size) of the waste plastic raw material mixture in the specific gravity differential separation, optical separation process, and electrostatic separation process, the mixture is separated into plastics with low specific gravity, such as polyolefins such as polypropylene and polyethylene, and plastics with high specific gravity, such as nitrogen-containing resins, and by adjusting the constituent ratios of each waste plastic obtained by separation in this manner, the content ratio of nitrogen-containing substances in the waste plastic raw material can be adjusted.

[0056] In addition, when waste plastic raw materials contain chlorine-containing resins, it is generally difficult to completely remove the chlorine-containing resins even after physical separation processes (e.g., foreign matter removal process, pulverization process, optical separation process, flotation separation process, and centrifugation process), and waste plastic raw materials usually contain a certain amount of chlorine-containing resins.

[0057] In some embodiments, in the pretreatment step, the nitrogen content in the waste plastic raw material may be adjusted by adding a nitrogen-containing substance to the waste plastic raw material after the separation step. In some embodiments, in the pretreatment step, the nitrogen content in the waste plastic raw material may be adjusted by adding a nitrogen-containing substance to the waste plastic raw material without going through the separation step.

[0058] The waste plastic raw material and its pre-processed products may be transported to each process using a transporter suitable for transporting powder, such as a blower, or a belt conveyor.

[0059] (2) Pyrolysis process The pyrolysis process is a process in which waste plastic raw materials are thermally decomposed at high temperatures to produce pyrolysis oil. There are no particular limitations on the pyrolysis method as long as it can convert waste plastic raw materials into oil. However, a method in which waste plastic raw materials are catalytically decomposed in the presence of an FCC (fluidized-bed catalytic cracking) catalyst is preferred because it can be decomposed at low temperatures and therefore produces high-quality products with little wax.

[0060] The pyrolysis temperature in the pyrolysis step is not particularly limited, but from the viewpoint of "improving oil yield," it is preferably carried out at a temperature of 350°C or higher, more preferably 400°C or higher, and even more preferably 420°C or higher. The upper limit of the pyrolysis temperature is not particularly limited, but from the viewpoint of "oil recovery rate," it is preferably 600°C or lower, more preferably 500°C or lower, and even more preferably 480°C or lower. The pyrolysis temperature is, for example, preferably 400 to 600°C, more preferably 350 to 600°C, more preferably 400 to 500°C, and even more preferably 420 to 480°C. It is preferable that a heat transfer medium is inserted into the reactor. The pressure in the pyrolysis step is, for example, preferably -0.1 to 0.1 MPa, more preferably -0.05 to 0.05 MPa, from the viewpoint of decomposition rate, and more preferably atmospheric pressure from the viewpoint of preventing air contamination. In some embodiments, the pressure in the pyrolysis step is atmospheric pressure.

[0061] In the thermal decomposition step, the FCC catalyst and the waste plastic raw material are preferably mixed and stirred by a stirring means. By mixing and stirring by the stirring means, the waste plastic comes into contact with the heat transfer medium, and the decomposition and gasification of the waste plastic occurs efficiently.

[0062] Examples of FCC catalysts include silica-alumina catalysts and zeolite catalysts, among which zeolite catalysts are preferred, and more preferably synthetic zeolite-based solid acid catalysts granulated into 40-80 μm particles used in the fluid catalytic cracking process of petroleum. FCC catalysts have an average specific gravity of 0.74-0.91, which is almost the same as that of waste plastics, so they can be thoroughly mixed with waste plastics in the reactor.

[0063] The FCC catalyst may be either a new catalyst or a used FCC catalyst (spent FCC catalyst). Spent FCC catalysts are regenerated catalysts used in the fluid cracking process, which selectively catalytically cracks a wide range of petroleum fractions, from light oil to atmospheric residue. They are also called equilibrium catalysts or regenerated catalysts. In petroleum refineries, catalysts are circulated between the catalytic cracking zone and the regeneration zone. To compensate for catalyst degradation, a predetermined amount of new catalyst is constantly replenished, and an amount of catalyst equivalent to this replenishment is discharged outside the system. The discharged spent catalyst still retains sufficient catalytic activity and is recycled within the system. Specifically, for example, a catalyst from a crude oil refinery is removed with coke and other particles attached. The accompanying hydrocarbons are stripped with steam, and then the catalyst is sent to a regeneration tower where air is blown in to burn the coke and activate the catalyst.

[0064] The amount of catalyst used is preferably 0.01 to 25 parts by weight, more preferably 0.05 to 20 parts by weight, and even more preferably 0.1 to 15 parts by weight per 100 parts by weight of waste plastic raw material. There are no particular restrictions on mixing the catalyst into the waste plastic raw material as long as it is done before the thermal decomposition is completed, but it is preferable to mix it in advance before the thermal decomposition starts because this results in high reaction efficiency. Note that although it is preferable to use an FCC catalyst in the thermal decomposition step, a catalyst other than an FCC catalyst may be used, or the thermal decomposition step may be carried out without using a catalyst.

[0065] The thermal decomposition reaction is preferably carried out under an inert gas atmosphere. Examples of the inert gas include hydrogen, helium, argon, nitrogen, and carbon dioxide, either singly or in a mixed gas of multiple inert gases in any ratio. Nitrogen is preferred, as it is industrially easy to handle, readily available, and relatively inexpensive. The inert gas may contain a trace amount of oxygen, but the oxygen content is preferably 0.1% or less, more preferably 100 ppm or less, in order to prevent oxidative degradation, coloration, and odor generation of the thermally decomposed wax.

[0066] There are no particular restrictions on the apparatus (pyrolysis apparatus) used to carry out the pyrolysis step, and any commonly used apparatus may be used, including a hot plate heater, an electric furnace, a tubular electric furnace, a quartz mantle heater, a kiln-type reactor such as a gas furnace, a gas-heated kiln, or an electrically heated kiln, a single-screw or twin-screw extruder, a stainless steel autoclave equipped with a stirrer, a quartz flask, a fluidized bed reactor, a solid-low bed reactor, a tubular reactor, a microwave heating furnace, etc. The pyrolysis apparatus preferably comprises a reactor for carrying out a catalytic cracking reaction, a heating means for heating the waste plastic raw material and the FCC catalyst in the reactor, a stirring means for stirring the waste plastic raw material and the FCC catalyst in the reactor, and a cooling device for cooling the cracked gas.

[0067] After pyrolysis, waste plastic pyrolysis oil is recovered from the products generated in the pyrolysis process. The pyrolysis products are separated into, for example, gaseous components at room temperature and liquid components at room temperature, and then utilized. If the recovered product after condensation contains an aqueous phase, it is preferable to separate the aqueous phase using a separatory funnel and recover the pyrolysis oil. Generally, the gaseous components of the pyrolysis products (waste plastic pyrolysis oil) at room temperature contain olefins such as ethylene, and can be used as light hydrocarbon gas after purification and recovery using an existing ethylene unit. Furthermore, the liquid components of the pyrolysis products (waste plastic pyrolysis oil) at room temperature can generally be used as crude oil equivalents. After pyrolysis, liquid pyrolysis oil can be recovered from the pyrolysis products (gas) by condensing them in a cooling tube. Furthermore, after pyrolysis, the pyrolysis products may be separated into LPG (liquefied petroleum gas), naphtha, or fuel oil (light oil fraction) by distillation.

[0068] The product of pyrolysis may contain ammonia (gas). According to some embodiments of the present invention, the product of pyrolysis may contain 0.1 vol ppm or more of ammonia. The upper limit of the ammonia contained in the product is not particularly limited, but from the viewpoint of alkaline corrosion, it is preferably 10,000 vol ppm or less, more preferably 5,000 vol ppm or less, and even more preferably 3,000 vol ppm or less. By keeping the amount of ammonia within the above range, corrosive substances derived from chlorine components can be neutralized. The ammonia contained in the product can also be removed by neutralizing it with an acid, if necessary.

[0069] The waste plastic pyrolysis oil obtained in the above-mentioned thermal decomposition process can be used as it is as a petroleum product such as fuel oil (e.g., light oil). However, since waste plastic pyrolysis oil generally contains a relatively large amount of impurities such as chlorine and nitrogen, the waste plastic pyrolysis oil may be refined to remove the impurities before use as a petroleum product.

[0070] (3) Petroleum Refining Process After the pyrolysis process, the waste plastic pyrolysis oil may be processed in a petroleum refining process. By refining in the petroleum refining process, impurities such as chlorine and nitrogen contained in the waste plastic pyrolysis oil can be removed, and the oil can be used as a variety of petroleum products. In addition, after the pyrolysis process, the waste plastic pyrolysis oil obtained above may be mixed with petroleum fractions derived from crude oil to obtain a mixed feedstock oil, which may be processed in a petroleum refining process. Petroleum products such as LPG (liquefied petroleum gas), naphtha, or fuel oil are produced by the petroleum refining process.

[0071] In some embodiments, the petroleum refining process includes at least one of hydrorefining, hydrocracking, and catalytic cracking. The petroleum refining process preferably includes a hydrorefining process, which reduces the sulfur, nitrogen, and metal contents of crude oil-derived components and also reduces the nitrogen, chlorine, and metal contents of pyrolysis oil. A preferred refining process involves mixing a petroleum fraction with a sulfur content of 0.5 to 5% by weight, particularly 1% by weight or more, with waste plastic pyrolysis oil, and subjecting the resulting mixture to hydrorefining to reduce the sulfur content to 1% by weight or less, particularly 0.5% by weight or less.

[0072] (Petroleum Fraction) The petroleum fraction is not particularly limited as long as it is a fraction consisting of hydrocarbons obtained using crude oil as a raw material, and examples thereof include straight-run naphtha, vacuum naphtha, thermally cracked naphtha, straight-run kerosene, vacuum kerosene, thermally cracked kerosene, straight-run diesel, vacuum diesel, thermally cracked diesel, and any mixtures thereof.

[0073] Regarding the distillation properties of the petroleum fraction, the 90% distillation temperature is preferably 300 to 600°C, particularly 400 to 600°C, and the difference from the 90% distillation temperature of the plastic cracked oil is preferably 200°C or less, particularly 100°C or less. The aromatic content of the petroleum fraction is preferably 10 to 50%, particularly 20 to 40%. If the 90% distillation temperature of the petroleum fraction is within this range, the petroleum fraction will have a large amount of aromatics and will have high solubility, which is preferable because it can be processed while suppressing coking.

[0074] The petroleum fraction preferably has a sulfur content of 0.05 to 10 wt%, particularly 0.1 to 5 wt%, a nitrogen content of 10 to 5,000 wt ppm, particularly 20 to 2,000 wt ppm, and a metal content (calcium, titanium, silicon, magnesium, iron, aluminum, copper, nickel, and vanadium) of 500 wt ppm or less, particularly 50 wt ppm or less.

[0075] (Mixed feedstock oil) A mixed feedstock oil obtained by mixing plastic cracking oil and petroleum fraction has a calcium content of 2 ppm by weight or less, preferably 1 ppm by weight or less, calculated as metal. It is desirable that the titanium and silicon contents are each 2 ppm by weight or less, preferably 1 ppm by weight or less, calculated as metal. The mixing ratio of waste plastic pyrolysis oil to the total mixed feedstock oil to be treated is preferably 50% by volume or less, particularly 25% by volume or less, and even more preferably 20% by volume or less. Within this range, the occurrence of coking and / or corrosion is prevented or suppressed, allowing for smooth treatment.

[0076] (Hydrotrefining) Hydrorotrefining involves contacting the treated oil with a hydrorefining catalyst in the presence of hydrogen. A preferred hydrorefining catalyst is one in which at least one of molybdenum, nickel, cobalt, and phosphorus, particularly molybdenum and at least one of nickel and cobalt, is supported on an inorganic porous carrier such as alumina. Preferred reaction conditions are a reaction temperature of 250 to 450°C, a reaction pressure of 1 to 25 MPa, and a liquid hourly space velocity (LHSV) of 0.1 to 30 h. －１ , H ２ / Oil (hydrogen / oil ratio): 20 to 5000 L / L.

[0077] After hydrorefining, the residue is separated into fractions such as LPG (liquefied petroleum gas) fraction, naphtha fraction, kerosene fraction, light oil fraction, and heavy light oil fraction, which can be used as is or after other petroleum refining processes to produce products such as petrochemical naphtha, gasoline, kerosene, light oil, and heavy oil, or base materials for such products. These can be used to produce LPG, naphtha, or fuel oil. In particular, petrochemical naphtha and gasoline base materials can have a sulfur content of 10 ppm by weight or less, particularly 2 ppm by weight or less, a nitrogen content of 10 ppm by weight or less, particularly 2 ppm by weight or less, a chlorine content of 10 ppm by weight or less, particularly 1 ppm by weight or less, a total acid number of 0.01 mgKOH / g or less, and a diene number of 0.2 g / 100 g or less, particularly 0.1 g / 100 g or less.

[0078] The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0079] (Methods for Measuring Physical Properties) The physical properties of the raw materials and products used in the examples and comparative examples were measured by the following methods: (1) Measurement of pH of wash water The pH of the wash water was measured by mixing the recovered oil (pyrolysis oil) with an equal weight of purified water for 2 minutes, and then measuring the pH of the resulting wash water using a pH meter (COMPACT pH METER, manufactured by HORIBA, Ltd.).

[0080] (2) Amount of ammonia in the off-gas (NH ３Quantitative analysis of ammonia in the off-gas was performed using a vacuum gas sampler (Komyo Rikagaku Kogyo Co., Ltd.) and a gas detector tube (Komyo Rikagaku Kogyo Co., Ltd.). The appropriate gas detector tube was used depending on the ammonia concentration generated, and the lowest detection limit of the detector tube with the smallest range was 0.2 vol ppm.

[0081] The materials used in each example are as follows: (1) Polypropylene (PP) (manufactured by Idemitsu Kosan Co., Ltd.) This was a powder (homo PP polymer, melt flow rate (MFR): 1 g / 10 min) sampled at the outlet of a PP polymerization reactor, which was deactivated with a small amount of pure water, and no additives were added. Appearance: Powder, Color: White

[0082] (2) Polyvinyl chloride (PVC) (Kondo Chemical Industry Co., Ltd., SRK-113) Appearance: Mixture of powder and granules (longest diameter: approximately 3.7 mm), Color: Gray

[0083] (3) Nylon 66 (PA6,6) (Toray Industries, Inc., AMILAN CM3001-N) -[CO-(CH ２ ) ４ -CONH-(CH ２ ) ６ -NH ｎ Nitrogen atom content: 12.4% by weight Appearance: powder, color: natural

[0084] (4) Electrostripper EA (Kao Corporation, Electrostripper EA 80001788) Lauryldiethanolamine (C １６ H ３５ NO ２ ) 200.4 mg KOH / g Nitrogen atom content: 5.1 wt% Appearance: Liquid, Color: Colorless to pale yellow transparent

[0085] (5) ABS (manufactured by Denka Co., Ltd., GR-2000) -[CH ２ -CH(CN)]-[CH ２ CH-CH-CH ２ ]-[CH ２ -CH(Ph)]- Nitrogen atom content: 6.6% by weight Appearance: Powder (longest diameter: approx. 3 mm), Color: Natural

[0086] [Test Example 1: pH behavior of cleaning water when PVC is added] To confirm that acidic gas is generated by decomposition of PVC, the pH behavior when PVC is added was confirmed. A thermal decomposition test was conducted using a PP sample without PVC and a PVC sample as waste plastic samples by the following method. The results are shown in Table 1.

[0087] (Thermal decomposition test) The thermal decomposition apparatus shown in Figure 3 was used. Tap water at 10°C was passed through the cooler, and a sodium hydroxide aqueous solution was prepared as a scrubber. An FCC catalyst and 100 g of the raw material waste plastic sample were placed in the reactor, stirred by a motor, and the reactor was heated to the reaction temperature of 420°C. A used FCC waste catalyst was used as the FCC catalyst. As the temperature in the reactor increased, the raw material waste plastic sample melted, and the vapor generated as a decomposition product passed through a reflux tower and was condensed in a cooling tube to be recovered as a product oil. The generated off-gas was trapped by a scrubber and made harmless before being discharged. The recovered oil (product oil) from the decomposition products was washed with purified water, and the pH of the wash water was measured. The simultaneously generated off-gas was analyzed for NH ３ The concentration was measured.

[0088]

[0089] As shown in Table 1, the pH of the cleaning water for the waste plastic sample not containing PVC was 6.5, while the pH of the cleaning water for the waste plastic sample containing PVC decreased and became acidic (pH 5.0).

[0090] [Test Example 2: pH Behavior of Cleaning Water When Nitrogen-Containing Substances Are Added] In addition to PP and PVC, nitrogen-containing substances were added as raw materials, and the behavior of the cleaning water increasing in pH and becoming alkaline was confirmed. Specifically, a waste plastic sample was prepared by adding PA6,6 (nylon 66), EA (electrostripper EA), or ABS as a nitrogen-containing substance to PP together with PVC, and a thermal decomposition test similar to that in Test Example 1 was carried out. The results are shown in Table 2.

[0091]

[0092] As shown in Table 2, it was confirmed that the pH of the cleaning water can be increased by adding a nitrogen-containing substance.

[0093] Test Example 3: pH Behavior of Cleaning Water When an Alkaline Earth Metal-Containing Substance is Simultaneously Added The pH behavior was examined when calcium hydroxide was simultaneously added as an alkaline earth metal-containing substance. Because alkaline earth metal-containing substances, which exhibit alkaline activity, react with acidic gases, it is expected that the simultaneous addition of an alkaline earth metal-containing substance will facilitate pH control. Specifically, a waste plastic sample was prepared by adding PA6,6 (nylon 66) and calcium hydroxide as nitrogen-containing substances to PP together with PVC, and a thermal decomposition test similar to that in Test Example 1 was conducted. The results are shown in Table 3.

[0094]

[0095] As shown in Table 3, it was confirmed that the pH of the wash water can be further increased by adding calcium hydroxide.

[0096] [Test Example 4: pH behavior of cleaning water when alkaline earth metal-containing substance is added simultaneously] The pH behavior of cleaning water was confirmed when the types of calcium hydroxide and nitrogenous substance added were changed. The results are shown in Table 4.

[0097]

[0098] As shown in Table 4, it was confirmed that the pH of the cleaning water increased and became more alkaline (higher pH) when calcium hydroxide was added, regardless of which nitrogen-containing substance was used.

[0099] Even if the waste plastics of the present invention contain chlorine-containing resins, the chlorine components are neutralized by the nitrogen components contained in the waste plastics during the pyrolysis process, thereby reducing or preventing problems such as corrosion and enabling stable production of pyrolysis oil. This allows for relaxation of restrictions on the content of chlorine-containing substances in the waste plastic raw material, greatly improving flexibility in the waste plastic discharge sources that can be used as raw materials, and making it possible to recycle a wide range of waste plastic raw materials.

[0100] 1 Reactor 2 FCC waste catalyst 3 Sample (batch) (PP powder, added resins) 4 Mantle heater 5 Scrubber (NaOH aq.) 6 Stirring motor 7 Reflux tower (gas temperature measurement) 8 Cooling tube 9 Separating funnel 10 Water + produced oil 11 Off-gas (detection tube) 12 Discharge

Claims

1. A method for producing waste plastic pyrolysis oil, comprising pyrolyzing waste plastic raw materials containing chlorine-containing resins to obtain waste plastic pyrolysis oil, and adjusting the nitrogen content in the waste plastic raw materials so that the pH of the water used to wash the pyrolysis oil exceeds 5.

0.

2. The manufacturing method according to claim 1, wherein the waste plastic pyrolysis oil is not neutralized and / or decomposed and removed from chlorine-containing compounds after pyrolysis.

3. The manufacturing method according to claim 1 or 2, wherein the nitrogen content in the waste plastic raw material is adjusted by: (i) adding a nitrogen-containing substance, and / or (ii) adjusting the content ratio of the nitrogen-containing substance in the waste plastic raw material to be subjected to thermal decomposition.

4. The manufacturing method described in claim 3, wherein the content ratio of nitrogen-containing substances in the waste plastic raw material is adjusted by adjusting the constituent ratio of the waste plastic obtained by separation from the waste plastic raw material mixture, and / or by adjusting the separation conditions of the waste plastic raw material mixture.

5. The manufacturing method according to claim 3 or 4, wherein the nitrogen-containing substance includes a nitrogen-containing compound and / or a nitrogen-containing resin, the nitrogen-containing compound is an amine, and the nitrogen-containing resin is at least one selected from the group consisting of polyamide resin, ABS resin, polyurethane resin, AS resin, urea resin, and melamine resin.

6. The manufacturing method according to any one of claims 3 to 5, wherein the nitrogen-containing substance is a substance that does not contain a nitrogen-oxygen bond.

7. The method according to any one of claims 1 to 6, wherein the thermal decomposition comprises catalytic decomposition of the waste plastic raw material in the presence of an FCC catalyst at a temperature of 400°C or higher.

8. The manufacturing method according to claim 7, wherein the waste plastic raw material contains an alkaline earth metal-containing substance that reacts with the chlorine component contained in the waste plastic raw material.

9. A manufacturing method described in any one of claims 1 to 7, wherein basic substances derived from nitrogen components produced by thermal decomposition of the waste plastic raw material react with chlorine components contained in the waste plastic raw material, causing the pH of the water used to wash the pyrolysis oil to exceed 5.

0.

10. A manufacturing method according to any one of claims 1 to 9, wherein the waste plastic raw material contains at least one selected from polyethylene, polypropylene, and polystyrene, and the content of chlorine atoms in the waste plastic raw material is 0.1% by weight or more.

11. A method for producing LPG, naphtha, or fuel oil, comprising mixing the waste plastic pyrolysis oil obtained according to any one of claims 1 to 10 with a petroleum fraction derived from crude oil, and processing the mixture in an oil refining process.

12. The method of claim 11, wherein the petroleum refining process includes at least one of hydrorefining, hydrocracking, and catalytic cracking.

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