Method for purifying liquid organic compound

Abstract

The present invention addresses the problem of providing a method for efficiently removing nitrogen-containing compounds and halogen-containing compounds from a liquid organic compound containing nitrogen-containing compounds and halogen-containing compounds, preferably a waste plastic decomposition oil.　The present invention includes a method for purifying a liquid organic compound, the method comprising a step for bringing a liquid organic compound (RM) containing nitrogen-containing compounds, halogen-containing compounds, and hydrocarbon compounds into contact with a monofunctional organic compound (A) and a bifunctional compound (B) and then separating the monofunctional organic compound (A) and the bifunctional compound (B).　The method satisfies the following requirements (i) to (iv). (i) The monofunctional organic compound (A) is a compound containing carbon, hydrogen, and oxygen, and the Hansen solubility parameter value [HSP-a] is 15-35 MPa0.5. (ii) The bifunctional compound (B) is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and the Hansen solubility parameter value [HSP-b] is 20-60 MPa0.5. (iii) The value of [HSP-b]-[HSP-a] is 3-40 MPa0.5. (iv) The mass ratio of the monofunctional organic compound (A) to the bifunctional compound (B) is 10 / 90 to 95 / 5.

Description

Method for purifying liquid organic compounds

[0001] The present invention relates to a method for purifying a liquid organic compound.

[0002] In recent years, there has been a trend of focusing on environmental issues. In particular, there has been mention of global warming and marine pollution caused by plastics, and measures are being considered such as reducing the use of fossil fuels such as oil and coal, preventing the dumping of waste plastic, and promoting its reuse.

[0003] It is well known that general-purpose resins such as polyolefins and polyvinyl chloride, and functional resins such as polyamides, polyethers, and polythioethers can be easily converted into oils by thermal decomposition to obtain cracked oils, which are promising candidates for recycling used resins. For example, the cracked oil can be recycled as recovered naphtha in existing petrochemical industry systems. Such a method can be considered more effective for materials that are not easily separated and recovered.

[0004] On the other hand, it is practically difficult to separate and recover all resins by type from everyday life. As a result, plastic decomposition oils often contain polyamides, such as nylon, nitrogen-containing compounds resulting from reactions between nitrogen in the air and plastics during the oily decomposition process, and / or chlorine-containing compounds resulting from polyvinyl chloride. Various stabilizers used in resin molding can also be sources of such heteroatoms. These so-called heteroatom-containing compounds can act as catalyst poisons in downstream processes or cause equipment corrosion, so they are generally required to be removed.

[0005] As methods for solving such problems, there have been disclosed methods of hydrotreating the cracked oil (Patent Document 1), steam treating it (Patent Document 2), contacting it with an inorganic acid (Patent Document 3), contacting it with an alkaline compound or water (Patent Document 4), and contacting it with a solid compound such as a metal oxide (Patent Document 5).

[0006] JP-A-9-48983, JP-A-9-48981, JP-A-9-48982, JP-A-2003-34794, Special Publication No. 11-504672

[0007] The methods of Patent Documents 1 to 5 are effective in reducing heteroatom-containing compounds such as nitrogen and chlorine from cracked oil. However, these methods may require relatively high energy consumption. Furthermore, it is difficult for each method to completely remove unwanted substances. According to the inventor's research, the methods of Patent Documents 1 to 5 sometimes result in relatively high residual rates of unique heteroatom-containing compounds, such as compounds with carbon-nitrogen multiple bond structures such as cyano groups and nitrogen-containing cyclic compounds such as pyrroles. In such cases, the methods may be combined with a relatively simple and efficient method for removing heteroatom-containing components, but there is still room for improvement.

[0008] In view of these problems, an object of the present invention is to provide a method for more efficiently removing nitrogen-containing compounds and halogen-containing compounds from liquid organic compounds (RM) containing carbon, hydrogen, nitrogen, and halogens, such as polymer decomposition oils, in a simple manner.

[0009] As a result of extensive research, the present inventors have found that a compound containing a specific plurality of compounds can efficiently extract and remove nitrogen-containing compounds and halogen-containing compounds from the liquid organic compound, and have thus completed the present invention. Therefore, the present invention can be specified as follows.

[0010] [1] A method for purifying a liquid organic compound, comprising the steps of contacting a liquid organic compound (RM) containing a nitrogen-containing compound, a halogen-containing compound, and a hydrocarbon compound with a monofunctional organic compound (A) and a bifunctional compound (B), and then separating the monofunctional organic compound (A) from the bifunctional compound (B). The method satisfies the following requirements (i) to (iv): (i) The monofunctional organic compound (A) is a compound containing carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-a] of 15 to 35 MPa. ０．５ (ii) The bifunctional compound (B) is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and has a Hansen solubility parameter value [HSP-b] of 20 to 60 MPa. ０．５ (iii) The value of [HSP-b]-[HSP-a] is 3 to 40 MPa. ０．５(iv) The mass ratio of the monofunctional organic compound (A) to the bifunctional compound (B) is 10 / 90 to 95 / 5. [2] In the above (i), [HSP-a] is 15 to 30 MPa. ０．５ [3] In the above (ii), [HSP-b] is 25 to 50 MPa. ０．５ [4] In the above (iii), [HSP-b]-[HSP-a] is 3 to 35 MPa. ０．５ [5] The method for purifying a liquid organic compound according to any one of [1] to [4], wherein the monofunctional organic compound (A) is an alcohol having 1 to 5 carbon atoms, and the bifunctional compound (B) is any one selected from the group consisting of glycols having 2 to 6 carbon atoms and water. [6] The method for purifying a liquid organic compound according to any one of [1] to [5], wherein the liquid organic compound (RM) is a decomposition oil of waste plastic.

[0011] According to the present invention, it is possible to provide a method for removing nitrogen-containing compounds and halogen-containing compounds from the liquid organic compound (RM) more efficiently in a simple manner.

[0012] Furthermore, the present invention can be easily combined with conventional methods. Therefore, the present invention is a useful method for purifying cracked oil obtained by decomposing polymers such as waste plastics, in an embodiment in which the content of heteroatom-containing compounds in the cracked oil is low. Therefore, by introducing the resulting refined cracked oil into a conventional naphtha cracker, the method is useful for obtaining ethylene, propylene, aromatic compounds, and the like. Therefore, this method is effective as a method for recycling, for example, waste plastics, and can be considered a useful technology from both an industrial and environmental perspective. Therefore, the present invention has great industrial significance.

[0013] Fig. 1 is a graph summarizing the results of the extraction rates of nitrogen compounds in Example 1 and Comparative Examples 1 and 2. Fig. 2 is a graph summarizing the results of the extraction rates of chlorine compounds in Example 1 and Comparative Examples 1 and 2.

[0014] The present invention will be described in further detail below. In this specification, the lower limit and upper limit of each numerical range can be combined arbitrarily.

[0015] <Method for purifying a liquid organic compound> The present invention provides a method for purifying a liquid organic compound, comprising the steps of contacting a liquid organic compound (RM) containing a nitrogen-containing compound, a halogen-containing compound, and a hydrocarbon compound with a monofunctional organic compound (A) and a bifunctional compound (B), and then separating the monofunctional organic compound (A) from the bifunctional compound (B).

[0016] The method satisfies the following requirements (i) to (iv): (i) the monofunctional organic compound (A) is a compound containing carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-a] of 15 to 35 MPa; ０．５ (ii) The bifunctional compound (B) is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and has a Hansen solubility parameter value [HSP-b] of 20 to 60 MPa. ０．５ (iii) The value of [HSP-b]-[HSP-a] is 3 to 40 MPa. ０．５ (iv) The mass ratio of the monofunctional organic compound (A) to the bifunctional compound (B) is 10 / 90 to 95 / 5.

[0017] [Liquid Organic Compound (RM)] The liquid organic compound to be purified in the method for purifying a liquid organic compound of the present invention is not particularly limited as long as it is a liquid organic compound (RM) containing a nitrogen-containing compound, a halogen-containing compound, and a hydrocarbon compound. Preferably, it is an organic compound obtained by liquefying a carbon-containing polymer (e.g., a resin or an elastomer) by a method such as thermal decomposition.

[0018] The polymers described above are preferably waste plastic molded articles for various uses. The plastics include various types, including both thermoplastic and thermosetting resins. Other examples of the polymers include elastomers, waxes, oils, and greases. Furthermore, so-called compositions containing multiple types of these are also examples of the polymers.

[0019] Examples of the thermoplastic resin include polyolefins (PO) such as polyethylene (PE) and polypropylene (PP); styrene-based resins such as polystyrene (PS) and high impact polystyrene (HIPS); copolymer resins of an olefin monomer with a small proportion of another monomer, such as ethylene-vinyl acetate copolymer resin (EVA); chlorine-containing resins such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC); oxygen-containing resins such as acrylic resins, such as polycarbonate, polymethyl acrylate, and polymethyl methacrylate resin; and nitrogen-containing resins such as various polyamides, polyimides, and ABS resins, typified by Nylon (trade name).

[0020] Examples of the thermosetting resin include phenol resin, melamine resin, urea resin, alkyd resin, polyurethane (PU), epoxy resin, and thermosetting polyimide.

[0021] As the polymer, the thermoplastic resin and the thermosetting resin may be used alone or in combination of two or more kinds.

[0022] Examples of the elastomers, waxes, oils, and greases include the following compounds: synthetic rubbers, such as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), styrene-butadiene copolymer rubber (SBR), butadiene-acrylonitrile copolymer rubber (NBR), chloroprene rubber (CR), polyisoprene rubber (IR), butyl rubber (IIR), polybutadiene rubber (BR), and crosslinked products (vulcanizates) thereof; and thermoplastic elastomers, such as partially crosslinked products of ethylene-propylene-non-conjugated diene copolymer rubber / polyethylene compositions, hydrogenated styrene-butadiene copolymers, and synthetic "hydrocarbon resins" such as those commonly known as "petroleum resins." Natural rubber can also be used.

[0023] Other examples include ethylene-based waxy or grease-like polymers and propylene-based waxy or grease-like polymers, such as atactic polypropylene. Liquid low-molecular-weight olefin polymers and mineral oils, which are components of engine oils, are also included. The above-mentioned elastomers, waxes, oils, and greases can be used alone or in combination.

[0024] Furthermore, all of the above-mentioned polymers can be used as a composition in which they are appropriately combined.

[0025] As the composition containing multiple components, an embodiment containing a high-melting point component (so-called resin) and a low-melting point component and / or a liquid component may be preferable from the viewpoint of heat conduction and decomposition efficiency during thermal decomposition.

[0026] The polymers that are the raw materials for the cracked oil used in the present invention are particularly preferably polyolefins such as polyethylene and polypropylene, or so-called polyolefin compounds that contain the above polyolefins and elastomers.

[0027] On the other hand, the polymers used as raw materials for cracked oil often contain nitrogen-containing polymers and / or chlorine-containing polymers. Examples of such components include the following polymers (including "resins" and "rubbers," also known as "crystalline polymers" and "amorphous or low-crystalline polymers"):

[0028] Nitrogen-containing polymers: polyamide resin (also known as "nylon"), ABS resin, butadiene-acrylonitrile copolymer rubber (NBR) Chlorine-containing polymers: polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), chloroprene rubber (CR)

[0029] The purification method of the present invention is highly effective for polymers containing the nitrogen-containing polymer and / or chlorine-containing polymer in an amount of usually 0.1 to 20% by weight, preferably 1 to 10% by weight (based on the total polymer amount).

[0030] Such polymers can be thermally decomposed by known methods to obtain cracked oils. According to the inventors' investigations, such cracked oils contain components believed to be derived from heteroatom-containing polymers. For example, nitrogen-containing compounds may contain amine compounds, as well as nitrogen-containing cyclic compounds such as pyridine and pyrrole, and compounds having a cyano group. Many of these nitrogen-containing compounds are basic and can be removed by contact with an inorganic acid, but compounds having a cyano group may be difficult to remove using the methods described in Patent Documents 1 to 5.

[0031] The cracked oil described above can be used as is in the present invention. Furthermore, the liquid organic compound (RM) is preferably a cracked oil obtained by decomposing waste plastics. The cracked oil may be subjected to a hydrogenation process using a catalyst, such as the hydrogenation process described below, or a contact treatment with an adsorbent such as a metal oxide.

[0032] [Monofunctional Organic Compound (A)] In the method for purifying a liquid organic compound of the present invention, a monofunctional organic compound (A) is used. In this specification, a monofunctional organic compound refers to a compound having one functional group in one molecule. The monofunctional organic compound (A) of the present invention is a compound containing carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-a] of 15 to 35 MPa. ０．５ The lower limit of the [HSP-a] is preferably 18 MPa. ０．５ , more preferably 20 MPa ０．５ , more preferably 22 MPa ０．５ On the other hand, the upper limit of the [HSP-a] is preferably 33 MPa. ０．５ , more preferably 31 MPa ０．５ , more preferably 30 MPa ０．５These upper and lower limits can be combined arbitrarily. If the Hansen solubility parameter value is within the above-mentioned relatively low range, it is considered that the affinity with the nitrogen-containing compound and halogen-containing compound in the liquid organic compound (RM) is high and that the nitrogen-containing compound and halogen-containing compound tend to be easily dissolved. In some cases, the compound may have the property of being easily separated from the liquid organic compound (RM). Furthermore, it is considered that the combination with the bifunctional compound (B) described below makes it difficult for the nitrogen-containing compound and halogen-containing compound to return to the liquid organic compound (RM) (reverse dissolution).

[0033] Examples of the monofunctional organic compound (A) include monoalcohols, monoketones, monoaldehydes, monothioalcohols, monocarboxylic acids, etc. Specific examples include monoalcohols such as methanol, ethanol, and propanol; monocarboxylic acids such as acetic acid and propionic acid; and monoketones such as acetone and methyl ethyl ketone. Among these, preferred are monoalcohols, more preferred are alcohols having 1 to 5 carbon atoms, even more preferred are methanol, ethanol, and isopropanol, and particularly preferred are methanol and ethanol, with methanol being particularly preferred.

[0034] [Bifunctional Compound (B)] In the method for purifying a liquid organic compound of the present invention, a bifunctional compound (B) is used. In this specification, the bifunctional compound refers to a compound having multiple functional groups in one molecule. The bifunctional compound (B) of the present invention is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-b] of 20 to 60 MPa. ０．５ The lower limit of the [HSP-b] is preferably 23 MPa. ０．５ , more preferably 25 MPa ０．５ , more preferably 28 MPa ０．５ On the other hand, the upper limit of the [HSP-b] is preferably 57 MPa. ０．５ , more preferably 55 MPa ０．５ , more preferably 53 MPa ０．５These upper and lower limits can be combined arbitrarily. It is believed that when the Hansen solubility parameter value is within the relatively low range, the solvent has a relatively high affinity with the nitrogen-containing compounds and halogen-containing compounds in the liquid organic compound (RM), and also tends to have a high affinity with the monofunctional organic compound (A), while tending to have a low affinity with the liquid organic compound (RM) as a whole. Therefore, it is believed that the solvent is easily separated from the liquid organic compound (RM), and when used in combination with the monofunctional organic compound (A), it tends to easily dissolve the nitrogen-containing compounds and halogen-containing compounds in the liquid organic compound (RM). In some cases, it is believed that the solvent tends to prevent the nitrogen-containing compounds and halogen-containing compounds from returning to the liquid organic compound (RM) (reverse dissolution).

[0035] Examples of such compounds include water, polyalcohols, polyketones, polyaldehydes, polythioalcohols, polycarboxylic acids, etc. Specific examples include water, polyalcohols such as ethylene glycol, propylene glycol, and glycerins, polycarboxylic acids such as maleic acid and fumaric acid, and polycarboxylic acid esters such as maleic acid diesters and fumaric acid diesters. Among these, water and polyalcohols are particularly preferred, and as alcohols, glycols having 2 to 6 carbon atoms are more preferred, with ethylene glycol and propylene glycol being even more preferred, and ethylene glycol being even more preferred. Water is particularly preferred as a bifunctional compound. In the present invention, water is defined as an inorganic compound containing two OH groups and is classified as a type of bifunctional compound (B).

[0036] [Relationship between monofunctional organic compound (A) and bifunctional compound (B)] The difference in Hansen solubility parameter value between the monofunctional organic compound (A) and the bifunctional compound (B), "[HSP-b] - [HSP-a]", is 3 to 40 MPa. ０．５ The upper limit of the difference is preferably 35 Pa. ０．５ and more preferably 30 Pa ０．５ and more preferably 25 Pa ０．５ The lower limit of the difference is preferably 4 Pa. ０．５and more preferably 6 Pa ０．５ and more preferably 8 Pa ０．５ Particularly preferably 10 Pa ０．５ In the present invention, the difference in Hansen solubility parameter values ​​being within a specific range is considered to have the effect of facilitating separation from the liquid organic compound (RM) and making it easier for nitrogen-containing compounds and halogen-containing compounds in the liquid organic compound (RM) to migrate to the monofunctional organic compound (A) and the bifunctional compound (B) and making it difficult for them to return.

[0037] The preferred ratio of the monofunctional organic compound (A) to the bifunctional compound (B) used may vary depending on the compounds used. In the present invention, the mass ratio of [monofunctional organic compound (A) / bifunctional compound (B)] is 10 / 90 to 95 / 5, preferably 13 / 87 to 92 / 8, more preferably 15 / 85 to 92 / 8, and even more preferably 15 / 85 to 90 / 10.

[0038] When the bifunctional compound (B) is an organic compound, the ratio of [monofunctional organic compound (A) / bifunctional compound (B)] is preferably 13 / 87 to 80 / 20, more preferably 15 / 85 to 70 / 30, and even more preferably 15 / 85 to 60 / 40.

[0039] When the bifunctional compound (B) is an inorganic compound, preferably water, the ratio of [monofunctional organic compound (A) / bifunctional compound (B)] is preferably 15 / 85 to 92 / 8, more preferably 30 / 70 to 92 / 8, and even more preferably 40 / 60 to 90 / 10.

[0040] The ratio of the total of the monofunctional organic compound (A) and the bifunctional compound (B) (total functional compounds) to the liquid organic compound (RM) can be appropriately set depending on the purpose and circumstances. Generally, the ratio is in the range of 1 / 99 to 99 / 1, preferably 5 / 95 to 95 / 5, more preferably 10 / 90 to 90 / 10, and even more preferably 20 / 80 to 80 / 20, in terms of the mass ratio of "total functional compounds / liquid organic compound (RM)."

[0041] The monofunctional organic compound (A) and the bifunctional compound (B) are usually mixed and then brought into contact with the liquid organic compound (RM), and the compounds are thoroughly contacted by stirring or shaking, and then allowed to stand to cause phase separation. After phase separation, the liquid organic compound layer and the functional compound layer are separated by a conventional method, such as removing the lower layer by liquid separation or removing the upper layer by decantation.

[0042] In addition to the above-mentioned contact order, it is also possible to use a method in which the bifunctional compound (B) is contacted with the liquid organic compound (RM) and then the monofunctional organic compound (A) is contacted therewith, a method in which the monofunctional organic compound (A) is contacted with the liquid organic compound (RM) and then the bifunctional compound (B) is contacted therewith, or a method in which the three components are contacted simultaneously. These methods can be appropriately selected depending on the components to be used.

[0043] The temperature at which the above-mentioned operation is carried out can be appropriately selected taking into consideration the boiling point and melting point of each main component. A specific preferred range is usually 10°C to 100°C. The lower limit of the temperature range is more preferably 15°C, even more preferably 20°C, and particularly preferably 25°C. When phase separation is difficult to occur, the lower limit is preferably 5°C, even more preferably 8°C, and particularly preferably 10°C. On the other hand, from the viewpoint of safety, the upper limit of the temperature range is more preferably 80°C, even more preferably 70°C, and particularly preferably 60°C. The above-mentioned operation can be repeated several times as necessary.

[0044] Furthermore, as will be shown in the examples described later, the method of the present invention can efficiently remove cyano group-containing compounds (nitrile compounds, etc.) and pyrroles that are difficult to thermally decompose, and is therefore suitable for obtaining a pyrolysis oil that can be used in combination with naphtha, etc.

[0045] As described above, the present invention is characterized by the use of a combination of the monofunctional organic compound (A) and the bifunctional compound (B) while taking into consideration the Hansen Solubility Parameter values. As can be seen from the results of the examples described below, the method of the present invention, which uses the monofunctional organic compound (A) and the bifunctional compound (B) in combination, may unexpectedly exhibit a higher removal efficiency from liquid organic compounds (RM) containing nitrogen-containing compounds, halogen-containing compounds, and hydrocarbon compounds than either the case where only the monofunctional organic compound (A) is contacted with the liquid organic compound (RM) or the case where only the bifunctional compound (B) is contacted with the liquid organic compound (RM). The reason for this effect is unknown. The inventor speculates as follows.

[0046] The monofunctional organic compound (A) is considered to be the main component that extracts nitrogen-containing and halogen-containing compounds from the liquid organic compound (RM). On the other hand, the bifunctional compound (B) has a relatively high Hansen solubility parameter value and is easily separated from the liquid organic compound (RM). Therefore, it may be effective in preventing the nitrogen-containing and halogen-containing compounds dissolved in the monofunctional organic compound (A) from dissolving back into the liquid organic compound (RM). It is also possible that the bifunctional compound (B) acts as an auxiliary agent for transferring nitrogen-containing and halogen-containing compounds from the liquid organic compound (RM) to the monofunctional organic compound (A). This unexpected effect is likely due to the Hansen solubility parameter values ​​of the monofunctional organic compound (A) and the bifunctional compound (B) falling within a specific range of values ​​and a specific difference.

[0047] The liquid organic compound (RM) is preferably a decomposition oil of waste plastics. In some cases, it may be preferable that the decomposition oil of waste plastics is treated with a catalyst, such as in the hydrotreating method described below, or by contact with a so-called adsorbent.

[0048] [Hydrogenation Catalyst] In the refining method of the present invention, the catalyst (hydrogenation catalyst) used in hydrotreating the liquid organic compound (RM) can be any known hydrotreating catalyst. Preferred examples are transition metal catalysts, and more preferred examples include transition metal oxide catalysts used in catalytic hydrorefining of petroleum. Particularly preferred catalysts include molybdenum oxide, nickel oxide, and cobalt oxide. A combination of these components can also be used.

[0049] Furthermore, in terms of catalytic efficiency, it is preferable to support these transition metal oxides on the surface of an appropriate particulate carrier made of one or more solid acids, such as alumina, silica, silica-alumina, titania, and zeolite, and one or more solid bases, such as magnesia, so that the transition metal oxides that exhibit catalytic performance can be selectively distributed on the carrier surface, allowing a given amount of catalyst to be utilized as efficiently as possible.

[0050] In the purification method of the present invention, a preferred embodiment for achieving the desired effect is to use the above-mentioned transition metal oxide catalyst supported on a powder carrier consisting of a solid acid and / or a solid base and having the following properties: The carrier has an average particle size of 50 to 50,000 μm, preferably 500 to 5,000 μm, and a specific surface area (measured by the BET method) of 0.1 to 1,000 m. ２ / g, preferably 10 to 300 m ２ / g.

[0051] [Hydrotreatment Step] When the hydrotreatment step is carried out in the purification method of the present invention, it can be carried out using various reaction systems (apparatuses), such as a (tank-type) batch reaction system or semi-batch reaction system, a continuous reaction system, a fixed bed system, a tubular reaction system, a fluidized bed system, or a moving bed system.

[0052] The hydrotreating step is carried out at a reaction temperature of 150 to 800° C. The lower limit of the temperature range is preferably 170° C., more preferably 180° C., and the upper limit is preferably 600° C., more preferably 450° C. These upper and lower limits can be arbitrarily combined, but the hydrotreating step is preferably carried out at a temperature of 170 to 600° C., more preferably 180 to 450° C.

[0053] For example, when the hydrotreating step is carried out by a batch reaction method, the method includes heating in the presence of 5 to 500 g, preferably 20 to 200 g, of the hydrogenation catalyst (based on transition metal oxide) per 1 kg of the cracked oil in the presence of hydrogen at a partial pressure of 0.1 to 15 MPa, preferably 0.3 to 10 MPa, at a reaction temperature of 150 to 800°C, preferably 170 to 600°C, more preferably 180 to 450°C, for typically 0.5 to 10 hours, preferably 1 to 3 hours, to decompose the nitrogen-containing compounds and / or chlorine-containing compounds.

[0054] When the hydrotreating step is carried out by a continuous reaction method, for example, a method can be used in which the hydrogenation catalyst is packed into a fixed bed and the cracked oil and hydrogen are continuously supplied. Regarding the operating conditions, the reaction temperature is 150 to 800°C, with the lower limit being preferably 170°C, more preferably 180°C, and the upper limit being preferably 600°C, more preferably 450°C. The preferred reaction pressure is 0.1 to 15 MPa, with the lower limit being more preferably 0.3 MPa, even more preferably 0.4 MPa, and the upper limit being preferably 10 MPa, more preferably 8.0 MPa. The preferred weight hourly space velocity (WHSV) is 0.1 to 100 h －１ The lower limit is more preferably 0.5 h －１ , more preferably 0.8 h －１ , particularly preferably 1.0 h －１ The upper limit is more preferably 50 h －１ , more preferably 10 h －１ , particularly preferably 5 h －１ , particularly preferably 3 h －１(The "h" represents time (hour)). A preferred excess amount of hydrogen is 1 to 100 times, with the lower limit being more preferably 2 times, even more preferably 3 times, and particularly preferably 5 times, and the upper limit being more preferably 50 times, even more preferably 30 times, and particularly preferably 20 times.

[0055] In the case of the continuous reaction method or semi-batch method, the cracked oil and hydrogen can of course be recycled and supplied to the hydrogenation catalyst.

[0056] Hydrogenation under the above conditions efficiently hydrogenates and cracks components containing multiple bonds in cracked oil. For example, when unsaturated hydrocarbon compounds such as olefins and dienes are present, this is preferable because saturated hydrocarbon compounds are produced. Furthermore, heteroatom-containing compounds such as nitrogen-containing compounds are decomposed into volatile nitrogen-containing compounds and low-molecular-weight amine compounds. These components can be easily removed by volatilizing them under low pressure.

[0057] On the other hand, according to the investigations of the present inventors, it has been found that although this hydrotreated cracked oil also contains nitrogen-containing cyclic compounds with relatively high molecular weights, such as pyrroles, compounds containing carbon-nitrogen multiple bond structures, such as the cyano group, are often effectively reduced.

[0058] [Contacting step with metal oxide] The liquid organic compound (RM) used in the present invention may be subjected to a contacting step with a metal oxide after adjusting the temperature by a method such as cooling or heating as appropriate. In this contacting step, the cracked oil is brought into contact with a solid component containing a metal oxide. This method can be performed by any known method, such as a batch method or a continuous method, without any restrictions.

[0059] The contacting step is carried out at a temperature lower than 150° C., and preferably at a temperature higher than room temperature and lower than 150° C. The lower limit of the temperature range is preferably 50° C., more preferably 60° C., even more preferably 70° C., and particularly preferably 80° C. Meanwhile, the upper limit is preferably 140° C., more preferably 130° C., even more preferably 125° C., and particularly preferably 120° C.

[0060] When the cracked oil is brought into contact with a metal oxide described below at such a temperature, heteroatom-containing compounds can be efficiently removed.

[0061] [Metal Oxide] The metal oxide can be any known metal oxide that exhibits the effect of removing heteroatom-containing compounds, such as nitrogen-containing compounds like amines and pyrroles. Examples of such metal oxides include aluminum oxide, aluminosilicates such as zeolites, iron oxide, zirconium oxide, and titanium oxide. Other examples include silicon dioxide, magnesium oxide, zinc oxide, copper oxide, calcium oxide, and sodium oxide. Among these, aluminum oxide, aluminosilicates such as zeolites, iron oxide, zirconium oxide, and titanium oxide are preferred, with aluminum oxide and aluminosilicates being even more preferred. Aluminum oxide is particularly preferred. These metal oxides may be used alone or in combination. By combining these metal oxides, the acidity, basicity, etc. can be adjusted, or, for example, by arranging multiple types in a multilayer structure, a composition suitable for a variety of heteroatom-containing compounds can be achieved.

[0062] The metal oxide may be in the form of the metal oxide itself, or in the form of a composition containing other components. Examples of other components include, without limitation, porous resins and other so-called supports. By using such supports in combination, it is possible to, for example, give the metal oxide a shape suitable for packing it into a column, or increase the surface area of ​​the metal oxide, thereby efficiently improving its performance per unit weight.

[0063] Examples of commercially available metal oxide products having the above-described properties include molecular sieves, activated alumina, activated zirconia, activated clay, kaolin, activated clay, and the like.

[0064] In the present invention, in consideration of the performance, availability, and reusability through calcination, etc., of the metal oxide, molecular sieves, activated alumina, and activated clay are preferred examples. Particularly preferred examples are activated alumina and activated clay, and activated clay is particularly preferred. (It is known that activated clay includes not only aluminum oxide and silica, but also iron oxide, magnesium oxide, etc.)

[0065] The ratio of the cracked oil to the metal oxide (metal oxide ratio = cracked oil / metal oxide) is preferably 2 to 1000 by weight. The lower limit is more preferably 4, even more preferably 5, and particularly preferably 6. On the other hand, the upper limit is more preferably 500, even more preferably 100, and particularly preferably 50.

[0066] The time for contacting the cracked oil with the metal oxide is preferably 1 minute to 24 hours. The lower limit is more preferably 5 minutes, even more preferably 8 minutes, and particularly preferably 10 minutes. On the other hand, the upper limit is more preferably 18 hours, even more preferably 12 hours, and particularly preferably 6 hours.

[0067] If the amount of the metal oxide is too small or the contact time is too short, the heteroatom-containing components may not be sufficiently removed, whereas if the amount of the metal oxide is too large or the contact time is too long, the cost tends to increase. Also, depending on the conditions, the metal oxide may alter the quality of the cracked oil.

[0068] As described above, the purification method of the present invention is preferably an embodiment in which a hydrotreatment step is carried out before the contact step.

[0069] As long as the above conditions are met, the hydrogenation step and the contact step with the metal oxide may be performed multiple times. Furthermore, other steps may be included within the scope that does not impair the effects of the present invention. For example, a method including a known step of removing heteroatom-containing compounds, such as treatment with an inorganic acid or steam treatment, may also be used.

[0070] As mentioned above, in the hydrotreating process, compounds having multiple bonds, such as cyano groups (e.g., nitriles), which are assumed to be difficult to remove, are likely converted to pyrroles, amines, etc. by the hydrogenation reaction. Therefore, by contacting the cracked oil obtained in the hydrotreating process with the metal oxide, heteroatom-containing compounds, such as the nitrogen compounds, are likely adsorbed or decomposed, making it possible to remove them from the cracked oil. Furthermore, when the metal oxide has adsorbent properties, it is generally believed that compounds having carbon-carbon multiple bonds, such as olefins, are also likely to be adsorbed. This may reduce the adsorption efficiency of the heteroatom-containing compounds. It is assumed that the hydrotreating process will reduce the content of compounds having multiple bonds, such as olefins, which makes it easier to adsorb and remove the heteroatom-containing compounds.

[0071] The liquid organic compounds obtained by the purification method of the present invention have reduced amounts of nitrogen-containing compounds, halogen-containing compounds, etc. Therefore, if they are supplied to a naphtha cracking process, for example, they can be expected to be converted into ethylene, propylene, 1-butene, butadiene, isoprene, benzene, toluene, xylene, styrene, and other unsaturated hydrocarbons that are useful as petrochemical feedstocks. Among these, ethylene and propylene are preferred because they can be used as feedstocks for a wide range of products.

[0072] Polymers such as synthetic plastics are used in a wide range of applications, but once their intended purpose is fulfilled, many of them have been disposed of by landfilling or incineration, or dumped as waste, leaving room for improvement in terms of their effective utilization. On the other hand, by using the refining method of the present invention, these polymers can be utilized as resources, similar to crude oil.

[0073] <Method for producing purified liquid organic compound> One embodiment of the present invention is a method for producing a purified liquid organic compound, comprising the steps of contacting a liquid organic compound (RM) containing a nitrogen-containing compound, a halogen-containing compound, and a hydrocarbon compound with a monofunctional organic compound (A) and a bifunctional compound (B), and then separating the monofunctional organic compound (A) from the bifunctional compound (B).

[0074] The method satisfies the following requirements (i) to (iv): (i) the monofunctional organic compound (A) is a compound containing carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-a] of 15 to 35 MPa; ０．５ (ii) The bifunctional compound (B) is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and has a Hansen solubility parameter value [HSP-b] of 20 to 60 MPa. ０．５ (iii) The value of [HSP-b]-[HSP-a] is 3 to 40 MPa. ０．５ (iv) The mass ratio of the monofunctional organic compound (A) to the bifunctional compound (B) is 10 / 90 to 95 / 5.

[0075] The meanings of the terms used in the production method are the same as those used in the "Method for Purifying a Liquid Organic Compound" above. The purified product obtained by the purification method and production method of the present invention can, of course, be further treated by other purification methods. Preferred examples include the hydrogenation treatment and contact treatment with an adsorbent.

[0076] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0077] [Waste Plastic Pyrolysis Oil] Waste plastic pyrolysis oil (main component: hydrocarbon) having the composition shown in Table 1 was prepared.

[0078]

[0079] The waste plastic pyrolysis oil was distilled, and the nitrogen and chlorine amounts in the fractions recovered at each boiling point were measured. The nitrogen and chlorine yields of each fraction relative to the raw material were integrated, and the results are shown in Table 2.

[0080]

[0081] The waste plastic pyrolysis oil contains nitrogen compounds and chlorine compounds over a wide boiling point range, with nitrogen compounds tending to be more abundant in the high boiling point region and chlorine compounds tending to be more abundant in the low boiling point region.

[0082] Furthermore, analysis of the nitrogen compounds using methods such as gas chromatography revealed that they contained cyano group-containing compounds and pyrroles.

[0083] [Hansen Solubility Parameter (HSP) of compounds used for extraction] Water (HSP: 47.8 MPa) ０．５ ) Methanol (MEOH) (HSP: 29.4 MPa ０．５ ) Ethanol (ETOH) (HSP: 26.5 MPa ０．５ ) Propylene glycol (PG) (HSP: 29.1 MPa ０．５ ) Isopropyl alcohol (IPA) (HSP: 23.6 MPa ０．５ The HSP of the mixtures in the examples was calculated by the usual method.

[0084] Example 1 Solvent Extraction Extraction was carried out using a methanol / water mixed solvent (methanol / water mass ratio of 16 / 84 to 88 / 12).

[0085] 10 ml of the waste plastic cracking oil and 10 ml of a methanol / water mixed solvent (methanol / water mass ratio of 16 / 84 to 88 / 12) as an extractant were charged into a reactor and stirred for 1 minute at room temperature and atmospheric pressure. After stirring, the mixture was allowed to stand for 1 hour, and a raffinate (corresponding to the waste plastic pyrolysis oil in this experiment) and an extract (corresponding to the aqueous methanol solution in this experiment) were separated. The weights of the charged raffinate and the recovered raffinate were measured, and the oil recovery rate (amount of raffinate recovered / amount of raffinate charged) was calculated. The nitrogen and chlorine contents of the raffinate were measured by chemiluminescence. The nitrogen extraction rate and chlorine extraction rate from the cracked oil were calculated, excluding the amounts of nitrogen and chlorine entrained due to the dissolution of the oil in the extractant. The results are shown in Table 3. Methanol concentration: 88 wt % (HSP: 31 MPa) ０．５) showed the highest extraction rate (nitrogen extraction rate 65%, chlorine extraction rate 39%).

[0086]

[0087] [Example 2] Extraction treatment was carried out in the same manner as in Example 1 using the pyrolysis oil and an ethanol / water mixed solvent (ethanol / water mass ratio 16 / 84 to 87 / 13) as an extractant. The results are shown in Table 4. The ethanol concentration was 87% by weight (HSP: 29 MPa). ０．５ ) showed the highest extraction rate (nitrogen extraction rate 50%, chlorine extraction rate 37%).

[0088]

[0089] [Example 3] Extraction treatment was carried out in the same manner as in Example 1 using the pyrolysis oil and a mixed solvent of isopropyl alcohol (IPA) / propylene glycol (PG) (IPA / PG mass ratio 16 / 84 to 34 / 66) as an extractant. The results are shown in Table 5. IPA concentration 16 wt% (HSP 28 MPa) ０．５ The highest nitrogen extraction rate (nitrogen extraction rate: 58%) was obtained when the IPA concentration was 25 wt% (HSP: 27 MPa). ０．５ ) showed the highest chlorine extraction rate (chlorine extraction rate: 33%).

[0090]

[0091] Comparative Example 1 The pyrolysis oil was extracted using water as an extractant in the same manner as in Example 1. The results are shown in Table 6 (nitrogen extraction rate with water: 12%, chlorine extraction rate: 8%).

[0092]

[0093] Comparative Example 2 The pyrolysis oil was extracted using methanol as an extractant in the same manner as in Example 1. The results are shown in Table 6 (nitrogen extraction rate with methanol: 22%, chlorine extraction rate: 15%).

[0094] Comparative Example 3: The pyrolysis oil was extracted using PG as an extractant in the same manner as in Example 1. The results are shown in Table 6 (nitrogen extraction rate with PG: 19%, chlorine extraction rate: 15%). (For reference, ETOH and IPA did not separate when mixed with the pyrolysis oil.)

[0095] Example 4: A cracked oil (nitrogen content: 230 ppm, containing cyano group-containing compounds and pyrroles) identical to that obtained by thermally decomposing waste plastics described in Example 1 of JP 2024-061111 A was prepared. This cracked oil was treated in the same manner as in Example 1 using an extractant with a composition of "MEOH / water = 65 / 35 (mass ratio)." The extraction process was performed in the same manner as in Example 1, except that the same process was repeated four times using the treated solution (a total of five treatments). The nitrogen content of the resulting treated solution was 10 ppm.

[0096] Comparative Example 4 Metal Oxide Contact Treatment 10 ml of the pyrolysis oil (nitrogen content: 230 ppm) and 0.7 g of activated clay (manufactured by Toshin Kasei Co., Ltd.) were added and stirred at 100°C and atmospheric pressure for 30 minutes. The activated clay was then filtered off by a conventional method. The nitrogen content of the resulting pyrolysis oil (filtrate) was 110 ppm, and cyano group-containing compounds were difficult to extract.

[0097] The above results suggest that the method of the present invention has excellent removal capabilities even for cyano group-containing compounds and pyrroles.

[0098] As described above, the unexpected result was that the combination of a monofunctional organic compound (methanol was used in Example 1) and a bifunctional compound (water was used in Example 1) resulted in a higher extraction rate of nitrogen-containing compounds and chlorine-containing compounds from cracked oil than the combination of either a monofunctional organic compound alone or a bifunctional organic compound alone. This is believed to be due to the effect of the bifunctional compound (B), which is easily separated from the cracked oil, preventing the nitrogen-containing compounds and chlorine-containing compounds dissolved in the monofunctional organic compound (A) from dissolving back into the cracked oil. This unexpected result is believed to be due to the fact that the Hansen solubility parameter values ​​of both the monofunctional organic compound (A) and the bifunctional compound (B) are in a specific numerical range and a specific difference range.

Claims

1. A method for purifying a liquid organic compound, comprising the steps of contacting a liquid organic compound (RM) containing a nitrogen-containing compound, a halogen-containing compound, and a hydrocarbon compound with a monofunctional organic compound (A) and a bifunctional compound (B), and then separating the monofunctional organic compound (A) from the bifunctional compound (B). The method satisfies the following requirements (i) to (iv): (i) The monofunctional organic compound (A) is a compound containing carbon, hydrogen, and oxygen, and has a Hansen Solubility Parameter value [HSP-a] of 15 to 35 MPa. ０．５ (ii) The bifunctional compound (B) is a compound containing two or more elements selected from carbon, hydrogen, and oxygen, and has a Hansen solubility parameter value [HSP-b] of 20 to 60 MPa. ０．５ (iii) The value of [HSP-b]-[HSP-a] is 3 to 40 MPa. ０．５ (iv) The mass ratio of the monofunctional organic compound (A) to the bifunctional compound (B) is 10 / 90 to 95 / 5.

2. In the above (i), [HSP-a] is 15 to 30 MPa ０．５ 2. The method for purifying a liquid organic compound according to claim 1, wherein 3. In the above (ii), [HSP-b] is 25 to 50 MPa ０．５ 2. The method for purifying a liquid organic compound according to claim 1, wherein 4. In the above (iii), [HSP-b]-[HSP-a] is 3 to 35 MPa ０．５ 2. The method for purifying a liquid organic compound according to claim 1, wherein 5. The method for purifying a liquid organic compound according to claim 1, wherein the monofunctional organic compound (A) is an alcohol having 1 to 5 carbon atoms, and the bifunctional compound (B) is one selected from the group consisting of glycols having 2 to 6 carbon atoms and water.

6. A method for purifying a liquid organic compound according to claim 1, wherein the liquid organic compound (RM) is a decomposition oil of waste plastics.

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