Hydrocarbon composition, production method therefor, method for producing lower-olefin composition, method for producing polyolefin-based polymer, and method for assessing hydrocarbon composition

Abstract

Provided are: a hydrocarbon composition; a production method therefor; a method for producing a lower-olefin composition; a method for producing a polyolefin-based polymer; and a method for assessing a hydrocarbon composition. The hydrocarbon composition includes a product of decomposition of a chemically recycled feedstock, and has an oxygen-containing compound content as determined by elemental analysis of 900 mass ppm or less in terms of oxygen atom amount. The chemically recycled feedstock comprises a polyolefin-based polymer and an oxygen-containing compound.

Description

Hydrocarbon composition and its manufacturing method, manufacturing method of lower olefin composition, manufacturing method of polyolefin polymer, and method for determining hydrocarbon composition

[0001] The present invention relates to a hydrocarbon composition and a method for producing the same. Furthermore, the present invention relates to a method for producing a lower olefin composition from the hydrocarbon composition. Furthermore, the present invention relates to a polyolefin polymer obtained by polymerizing the lower olefin composition. Furthermore, the present invention relates to a method for determining a hydrocarbon composition.

[0002] Plastics are widely used in a variety of products, such as containers for beverages, packaging materials for food, household goods, and automobile parts. However, in order to reduce the environmental impact and waste of resources, reprocessing waste plastics and converting them into new products or materials as recycled plastics has become an important issue from the perspectives of environmental protection and sustainability. Therefore, in recent years, methods have been considered in which plastic decomposition oil is obtained from waste plastics using known pyrolysis methods such as thermal recycling and chemical recycling, and the obtained decomposition oil is further distilled to obtain a decomposition refined oil.

[0003] On the other hand, a typical known method for producing lower olefins is to thermally crack naphtha (a crude oil-derived hydrocarbon mixture having a boiling point range of about 30 to 230°C) obtained by refining crude oil in the presence of steam using a naphtha cracker facility. Furthermore, in recent years, studies have been conducted on the production of lower olefins using plastic cracking oil obtained from waste plastics as a raw material.

[0004] According to the studies of the present inventors, it has been found that pyrolysis oils, such as plastic cracking oils obtained from chemically recycled raw materials such as waste plastics, contain oxygen-containing compounds, and that when this pyrolysis oil is thermally cracked to produce various lower olefins, the amount of carbon monoxide (CO) produced by decomposition of the oxygen-containing compounds in the cracker equipment increases significantly, which can poison the catalyst in the downstream hydrogenation tank and, if the oxygen-containing compound is an organic acid, can cause corrosion of the equipment. It has also been found that methanol derived from the pyrolysis products of the oxygen-containing compounds is produced in the obtained lower olefin products. If methanol derived from the pyrolysis products of the oxygen-containing compounds is mixed with lower olefin products such as propylene, it may degrade the performance of the catalyst used to polymerize the lower olefins to produce olefin polymers such as polypropylene.

[0005] As a technique for refining plastic cracked oil produced by thermal decomposition of waste plastics, for example, Patent Document 1 discloses a method of directly hydrorefining the waste plastic cracked oil. Patent Documents 2 and 3 disclose methods for reducing catalyst coking by diluting the waste plastic cracked oil with diesel and hydrorefining it. Patent Document 4 discloses a method for producing high-quality jet fuel using a hydrogenation catalyst and an isomerization catalyst in a hydrorefining process. Non-Patent Document 1 discloses a method for removing sulfur-containing compounds, nitrogen-containing compounds, and the like from petroleum-derived naphtha by hydrorefining the petroleum-derived naphtha.

[0006] Japanese Patent Laid-Open No. 09-048983 Japanese Patent Laid-Open No. 2007-77324 Japanese Patent Laid-Open No. 2005-105027 Japanese Patent Laid-Open No. 2020-90660

[0007] Hydrogen Energy System Vol. 33, No. 2 (2008)

[0008] However, the methods described in Patent Documents 1 to 4 were unable to sufficiently reduce the oxygen-containing compounds in the plastic cracked oil. In particular, the methods described in Patent Documents 2 and 3 were not economically viable because they required a step of diluting the waste plastic cracked oil with diesel. Furthermore, the method described in Non-Patent Document 1 was unable to sufficiently reduce not only the oxygen-containing compounds in petroleum-derived naphtha but also the oxygen-containing compounds in the plastic cracked oil.

[0009] An object of the present invention is to solve these problems. Specifically, an object of the present invention is to provide a hydrocarbon composition containing decomposition products of waste plastics and having a reduced concentration of oxygen-containing compounds, a method for producing the hydrocarbon composition, and a method for assessing the quality of the hydrocarbon composition. Another object of the present invention is to provide a method for producing a lower olefin composition using the hydrocarbon composition. A further object of the present invention is to provide a polyolefin polymer obtained by polymerizing the lower olefin composition.

[0010] As a result of extensive investigations aimed at solving the above-mentioned problems, the inventors have discovered that the content of oxygen-containing compounds can be significantly reduced by hydrogenating and dehydrating pyrolysis oil produced by the thermal decomposition of waste plastics in the presence of two independent catalysts during purification, thereby solving the above-mentioned problems and completing the present invention. [1] A method for producing a hydrocarbon composition, comprising purifying pyrolysis oil produced by the thermal decomposition of a chemically recycled feedstock to obtain a hydrocarbon composition, wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound, and the pyrolysis oil contains an oxygen-containing compound, and the purification process comprises hydrogenating and dehydrating the oxygen-containing compounds in the pyrolysis oil in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst). [2] A method for producing a hydrocarbon composition according to [1], comprising reducing the amount of oxygen-containing compounds in the pyrolysis oil by the hydrogenation and dehydration reactions. [3] A method for producing a hydrocarbon composition according to [1] or [2], which comprises converting at least a portion of the oxygen-containing compounds in the pyrolysis oil into paraffins by the hydrogenation reaction and the dehydration reaction. [4] A method for producing a hydrocarbon composition according to any one of [1] to [3], which comprises obtaining a pyrolysis product by thermal decomposition of the chemically recycled feedstock without a catalyst. [5] A method for producing a hydrocarbon composition according to any one of [1] to [4], which comprises carrying out the hydrogenation reaction or the dehydration reaction in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, as measured by elemental analysis, is 900 ppm by mass or less in terms of oxygen atoms. [6] A method for producing a hydrocarbon composition according to any one of [1] to [5], which comprises carrying out the hydrogenation reaction and / or the dehydration reaction in the purification treatment so that the content of olefinic compounds in the obtained hydrocarbon composition, as measured by PONA analysis, is 180 ppm by mass or less. [7] The method for producing a hydrocarbon composition according to any one of [1] to [6], wherein the mass ratio of the hydrogenation catalyst to the dehydration catalyst used in the purification treatment is 0.5 or more and 90 or less.[8] A method for producing a hydrocarbon composition according to any one of [1] to [7], wherein the total mass of the dehydration catalyst and hydrogenation catalyst used in the purification treatment is 300 mass% or more and 2000 mass% or less, based on the oxygen atom equivalent amount of oxygen-containing compounds in the pyrolysis oil. [9] A method for producing a hydrocarbon composition according to any one of [1] to [8], wherein the hydrogenation catalyst and the dehydration catalyst exist independently in the purification treatment.

[10] A method for producing a hydrocarbon composition according to any one of [1] to [9], wherein the chemically recycled feedstock contains waste plastic.

[11] A method for producing a hydrocarbon composition according to any one of [1] to

[10] , wherein the chemically recycled feedstock contains biomass.

[12] A method for producing a hydrocarbon composition according to any one of [1] to

[11] , wherein the chemically recycled feedstock contains 60 mass% or more of a polyolefin polymer, based on the total mass of the chemically recycled feedstock.

[13] The method for producing a hydrocarbon composition according to any one of [1] to

[12] , wherein the purification treatment comprises carrying out the hydrogenation reaction or the dehydration reaction so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 260 ppm by mass or less in terms of oxygen atoms.

[14] The method for producing a hydrocarbon composition according to any one of [1] to

[13] , wherein the oxygen-containing compound comprises at least one compound selected from the group consisting of alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds.

[15] The method for producing a hydrocarbon composition according to

[14] , wherein the content of alcohol-based compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 40 ppm by mass or less in terms of oxygen atoms.

[16] The method for producing a hydrocarbon composition according to

[14] or

[15] , wherein the content of ketone-based compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 70 ppm by mass or less in terms of oxygen atoms.

[17] A method for producing a hydrocarbon composition according to any one of

[14] to

[16] , wherein the content of carboxylic acid compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 30 ppm by mass or less in terms of oxygen atoms.

[18] A method for producing a hydrocarbon composition according to any one of

[14] to

[17] , wherein the content of aldehyde compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 15 ppm by mass or less in terms of oxygen atoms.

[19] A method for producing a hydrocarbon composition according to any one of

[14] to

[18] , wherein the content of ether compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 5 ppm by mass or less in terms of oxygen atoms.

[20] A method for producing a hydrocarbon composition according to any one of [1] to

[19] , wherein the hydrogenation catalyst contains at least one metal selected from transition metals belonging to Groups 8 to 10 of the Periodic Table.

[21] The method for producing a hydrocarbon composition according to any one of [1] to

[20] , wherein the dehydration catalyst comprises at least one selected from the group consisting of silica, alumina, silica-alumina, and zeolite.

[22] A hydrocarbon composition comprising a decomposition product of a chemically recycled feedstock, wherein the content of oxygen-containing compounds measured by elemental analysis is 900 mass ppm or less in terms of oxygen atoms, and the chemically recycled feedstock comprises a polyolefin polymer and an oxygen-containing compound.

[23] A method for producing a lower olefin composition, comprising purifying a pyrolysis oil produced by thermal decomposition of a chemically recycled feedstock, wherein the chemically recycled feedstock comprises a polyolefin polymer and an oxygen-containing compound, and wherein the purification process comprises hydrogenating and dehydrating the oxygen-containing compounds in the pyrolysis oil in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) to obtain the hydrocarbon composition, and wherein the hydrocarbon composition is obtained by thermally decomposing the hydrocarbon composition in a naphtha cracker.

[24] A method for producing a polyolefin polymer, comprising: obtaining a lower olefin composition by the method for producing a lower olefin composition according to

[23] ; and polymerizing the lower olefin contained in the lower olefin composition to obtain a polyolefin polymer.

[25] A method for determining a hydrocarbon composition to be used in the production of lower olefins, wherein the hydrocarbon composition is a hydrocarbon composition containing decomposition products of a chemically recycled feedstock; and when a measured value of the content of oxygen-containing compounds in the hydrocarbon composition is equal to or less than a predetermined threshold, determining the hydrocarbon composition as acceptable for use in the production of lower olefins, and subjecting the hydrocarbon composition to a thermal decomposition treatment.

[26] The method for determining a hydrocarbon composition according to

[25] , wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound.

[27] The method for determining a hydrocarbon composition according to

[25] or

[26] , wherein the hydrocarbon composition is a hydrocarbon composition obtained by purifying a pyrolysis oil produced by thermal decomposition of a chemically recycled feedstock.

[28] The method for determining a hydrocarbon composition according to

[27] , wherein the refining treatment comprises subjecting oxygen-containing compounds in the thermal cracking oil to a hydrogenation reaction and a dehydration reaction under a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst).

[29] The method for determining a hydrocarbon composition according to any one of

[25] to

[28] , wherein the hydrocarbon composition is a mixture containing a cracking product of a chemical recycling feedstock and another naphtha prepared in advance.

[30] The method for determining a hydrocarbon composition according to any one of

[25] to

[29] , wherein the hydrocarbon composition is acceptable as a hydrocarbon composition to be used for producing lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured using elemental analysis, is 900 mass ppm or less in terms of oxygen atoms.

[31] The method for determining a hydrocarbon composition according to any one of

[25] to

[30] , comprising determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the content of olefinic compounds in the hydrocarbon composition, as measured using the PONA analytical method, is 180 mass ppm or less.

[32] The method for determining a hydrocarbon composition according to any one of

[25] to

[31] , comprising determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured by gas chromatography, is 260 ppm by mass or less in terms of oxygen atoms.

[33] The method for determining a hydrocarbon composition according to any one of

[25] to

[32] , wherein the chemically recycled feedstock contains waste plastic.

[34] The method for determining a hydrocarbon composition according to any one of

[25] to

[33] , wherein the chemically recycled feedstock contains biomass.

[35] The method for determining a hydrocarbon composition according to any one of

[25] to

[34] , wherein the chemically recycled feedstock contains 60% by mass or more of a polyolefin polymer based on the total mass of the chemically recycled feedstock.

[36] The method for determining a hydrocarbon composition according to any one of

[25] to

[35] , wherein the determination is made immediately before the hydrocarbon composition is fed into a naphtha cracker.

[0011] [X1] A hydrocarbon composition containing a decomposition product of waste plastics, wherein the content of oxygen-containing compounds measured by elemental analysis is 900 mass ppm or less in terms of oxygen atoms.

[0012] [X2] The hydrocarbon composition according to [X1], wherein the content of oxygen-containing compounds measured by gas chromatography is 160 mass ppm or less in terms of oxygen atoms.

[0013] [X3] The hydrocarbon composition according to [X1] or [X2], wherein the oxygen-containing compound comprises at least one compound selected from the group consisting of alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds.

[0014] [X4] The hydrocarbon composition according to any one of [X1] to [X3], wherein the content of alcohol compounds as the oxygen-containing compounds, as measured by gas chromatography, is 40 ppm by mass or less in terms of oxygen atoms.

[0015] [X5] The hydrocarbon composition according to any one of [X1] to [X4], wherein the content of ketone compounds as the oxygen-containing compounds, as measured by gas chromatography, is 70 ppm by mass or less in terms of oxygen atoms.

[0016] [X6] The hydrocarbon composition according to any one of [X1] to [X5], wherein the content of the carboxylic acid compound as the oxygen-containing compound, as measured by gas chromatography, is 30 ppm by mass or less in terms of oxygen atoms.

[0017] [X7] The hydrocarbon composition according to any one of [X1] to [X6], wherein the content of aldehyde compounds as the oxygen-containing compounds, as measured by gas chromatography, is 15 mass ppm or less in terms of oxygen atoms.

[0018] [X8] The hydrocarbon composition according to any one of [X1] to [X7], wherein the content of ether compounds as the oxygen-containing compounds, as measured by gas chromatography, is 5 ppm by mass or less in terms of oxygen atoms.

[0019] [X9] The hydrocarbon composition according to any one of [X1] to [X8], wherein the hydrocarbon composition is a mixture containing a decomposition product of waste plastic and another naphtha prepared in advance.

[0020] [X10] A method for producing a lower olefin composition, comprising a hydrocarbon composition cracking step of cracking the hydrocarbon composition according to any one of [X1] to [X9].

[0021] [X11] A lower olefin composition containing a lower olefin and / or a derivative of the lower olefin, which is a cracking product of the hydrocarbon composition according to any one of [X1] to [X9].

[0022] [X12] A polyolefin polymer obtained by polymerizing the lower olefin and / or its derivative contained in the lower olefin composition according to [X11].

[0023] [X13] A method for producing a hydrocarbon composition, comprising purifying a cracked oil (i.e., thermal cracked oil, preferably plastic cracked oil) produced by the thermal decomposition of waste plastics to obtain a hydrocarbon composition, wherein the purification process comprises subjecting oxygen-containing compounds in the cracked oil (i.e., thermal cracked oil, preferably plastic cracked oil) to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst).

[0024] [X14] The method for producing a hydrocarbon composition according to [X13], wherein the hydrogenation catalyst and the dehydration catalyst are present in an independent state in the refining treatment.

[0025] [X15] A method for producing a hydrocarbon composition according to [X13] or [X14], comprising controlling the reaction conditions of the hydrogenation reaction or the dehydration reaction in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, as measured by elemental analysis, is 900 mass ppm or less in terms of oxygen atoms.

[0026] [X16] A method for producing a hydrocarbon composition according to any one of [X13] to [X15], comprising controlling the reaction conditions of the hydrogenation reaction or the dehydration reaction in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 260 ppm by mass or less (preferably 160 ppm by mass or less) in terms of oxygen atoms.

[0027] [X17] The method for producing a hydrocarbon composition according to any one of [X13] to [X16], wherein the mass ratio of the hydrogenation catalyst to the dehydration catalyst used in the purification treatment is 0.5 (preferably 10 or more) to 90 or less.

[0028] [X18] The method for producing a hydrocarbon composition according to any one of [X13] to [X17], wherein the total mass of the dehydration catalyst and the hydrogenation catalyst used in the purification treatment is 300% by mass or more and 2000% by mass or less, based on the oxygen atom-equivalent amount of oxygen-containing compounds in the cracked oil (i.e., thermal cracked oil, preferably plastic cracked oil).

[0029] [X19] The method for producing a hydrocarbon composition according to any one of [X13] to [X18], wherein the oxygen-containing compound comprises at least one selected from the group consisting of alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds.

[0030] [X20] The method for producing a hydrocarbon composition according to any one of [X13] to [X19], wherein the content of alcohol compounds as the oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 40 mass ppm or less in terms of oxygen atoms.

[0031] [X21] The method for producing a hydrocarbon composition according to any one of [X13] to [X20], wherein the content of ketone compounds as the oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 70 mass ppm or less in terms of oxygen atoms.

[0032] [X22] The method for producing a hydrocarbon composition according to any one of [X13] to [X21], wherein the content of a carboxylic acid compound as the oxygen-containing compound in the obtained hydrocarbon composition, as measured by gas chromatography, is 30 ppm by mass or less in terms of oxygen atoms.

[0033] [X23] The method for producing a hydrocarbon composition according to any one of [X13] to [X22], wherein the content of aldehyde compounds as the oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 15 mass ppm or less in terms of oxygen atoms.

[0034] [X24] The method for producing a hydrocarbon composition according to any one of [X13] to [X23], wherein the content of ether compounds as the oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 5 ppm by mass or less in terms of oxygen atoms.

[0035] [X25] The method for producing a hydrocarbon composition according to any one of [X13] to [X24], wherein the hydrogenation catalyst contains at least one metal selected from transition metals belonging to Groups 8 to 10 of the periodic table.

[0036] [X26] The method for producing a hydrocarbon composition according to any one of [X13] to [X25], wherein the dehydration catalyst comprises at least one selected from the group consisting of silica, alumina, silica alumina, and zeolite.

[0037] [X27] A method for determining a hydrocarbon composition to be used in the production of lower olefins, the hydrocarbon composition being a hydrocarbon composition containing decomposition products of waste plastics, the method comprising determining that the hydrocarbon composition is acceptable as a hydrocarbon composition to be used in the production of lower olefins when a measured value of the content of oxygen-containing compounds in the hydrocarbon composition is equal to or less than a predetermined threshold value, and subjecting the hydrocarbon composition to a thermal cracking treatment.

[0038] [X28] The method for determining a hydrocarbon composition according to [X27], wherein the hydrocarbon composition is a hydrocarbon composition obtained by purifying cracked oil (i.e., thermal cracked oil, preferably plastic cracked oil) produced by thermal decomposition of waste plastic.

[0039] [X29] The method for determining a hydrocarbon composition according to [X27] or [X28], wherein the hydrocarbon composition is a mixture containing a decomposition product of waste plastics and another naphtha prepared in advance.

[0040] [X30] A method for determining a hydrocarbon composition according to any one of [X27] to [X29], comprising determining that the hydrocarbon composition is acceptable for use in producing lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured using elemental analysis, is 900 mass ppm or less in terms of oxygen atoms.

[0041] [X31] A method for determining a hydrocarbon composition according to any one of [X27] to [X30], comprising determining that the hydrocarbon composition is acceptable for use in producing lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured using gas chromatography, is 160 mass ppm or less in terms of oxygen atoms.

[0042] According to the present invention, in chemical recycling using chemically recycled raw materials such as waste plastics as raw materials, pyrolysis oil such as plastic cracked oil produced by thermal decomposition can be refined to provide a hydrocarbon composition with a reduced content of oxygen-containing compounds.

[0043] According to the method for producing a hydrocarbon composition of the present invention, a hydrocarbon composition with a reduced content of oxygen-containing compounds can be efficiently produced by refining a pyrolysis oil, such as a plastic cracking oil, obtained by pyrolyzing a chemically recycled raw material such as waste plastics.

[0044] The hydrocarbon composition provided by the present invention has a low content of oxygen-containing compounds, and therefore, when the hydrocarbon composition is thermally cracked to produce various lower olefins, the amount of carbon monoxide (CO) produced by decomposition of the oxygen-containing compounds in a cracker facility can be prevented from significantly increasing, which would otherwise poison the catalyst in a downstream hydrogenation tank. Furthermore, when the oxygen-containing compounds contain an organic acid, corrosion of the equipment can be prevented.

[0045] In the method for producing a lower olefin composition provided by the present invention, the hydrocarbon composition of the present invention is thermally decomposed to obtain the lower olefin composition, and therefore the concentration of methanol derived from the thermal decomposition product of the oxygen-containing compound is reduced. As a result, when the lower olefin composition is polymerized to produce an olefin polymer such as polypropylene, deterioration of the performance of the polymerization catalyst can be suppressed.

[0046] According to the method for determining a hydrocarbon composition of the present invention, it is possible to accurately determine whether a hydrocarbon composition containing decomposition products of waste plastics is suitable as a hydrocarbon composition to be used in the production of lower olefins.

[0047] The present invention will be described in detail below. The present invention is not limited to the following description, and can be practiced in any modified form without departing from the gist of the present invention.

[0048] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. "A to B" means greater than or equal to A and less than or equal to B. In this specification, "mass %" indicates the content ratio of a specified component contained in 100% by mass of the total amount, and "mass %" indicates the content ratio of a specified component contained in 100% by mass of the total amount. "mass %" and "weight %" have the same meaning. "Optional" or "optionally" means that the subsequently described situation may or may not occur, and therefore, the description includes both the occurrence and non-occurrence of the situation. All steps described in this specification can be performed in any suitable order unless otherwise specified in the specification or clearly contradicted by context.

[0049] In this specification, "chemically recycled raw materials" refers to waste plastics and biomass. In this specification, "waste plastics" refers to used plastic products and plastic materials (hereinafter referred to as "used plastic products, etc."), specifically materials that have been used once and then discarded, and that may be reused, recycled, or disposed of, and refers to materials that produce pyrolysis oil through chemical recycling. Furthermore, "biomass" refers to organic matter of biological origin, including organic matter from plants, animals, microorganisms, etc., and specifically includes wood, agricultural residues, paper, food waste, compost, livestock excrement, and even organic matter obtained from microorganisms, and refers to materials that produce pyrolysis oil through chemical recycling.

[0050] In this specification, the term "thermal decomposition" in "thermal decomposition of waste plastics" refers to any method that can decompose waste plastics to obtain plastic decomposition oil (sometimes simply referred to as "cracked oil" or "thermal decomposition oil"). Examples of such methods include conventional thermal decomposition processes, known decomposition processes using supercritical or subcritical fluids, such as known hydrothermal decomposition processes, and known catalytic pyrolysis processes. The term "conventional thermal decomposition process" refers to the thermochemical decomposition of organic substances under substantially oxygen-free conditions without external oxygen supply, solely under the influence of temperature. More specifically, those skilled in the art can appropriately optimize the thermal decomposition reaction temperature, residence time, type of reactor, pressure, and type of catalyst in the thermal decomposition reactor to perform the thermal decomposition process. The term "decomposition treatment using a supercritical fluid or subcritical fluid" refers to a thermochemical decomposition treatment of organic substances by adjusting the temperature and pressure to utilize the high reactivity of supercritical fluids or subcritical fluids close to a supercritical state, in which solvents such as methanol or water, or gases such as CO2, are rendered neither liquid nor gaseous. When water is used as the fluid, thermal decomposition (hydrothermal decomposition) is performed in the presence of water. Specifically, when water is used, the temperature and pressure are controlled to heat the water to 100 to 700°C, more preferably to 150 to 500°C, and the high reactivity of supercritical water or subcritical water is utilized for hydrothermal decomposition treatment. Furthermore, the term "contact pyrolysis treatment" refers to a thermochemical decomposition treatment of organic substances in the presence of a known pyrolysis catalyst, under substantially oxygen-free conditions without external oxygen supply, at a high temperature range, under the influence of the pyrolysis catalyst and temperature. Specifically, waste plastics are melted and pyrolyzed using a known heating means such as an extruder, and the resulting melt, vapor, or both are brought into contact with a pyrolysis catalyst to lighten the waste plastics. Examples of the pyrolysis catalyst include inorganic solid acid oxide particles such as silica-alumina, silica-titania, silica-zirconia, alumina-magnesia, alumina-zirconia, alumina-titania, bentonite, kaolinite, and zeolite.

[0051] In the present invention, the term "lower olefin" refers to an unsaturated hydrocarbon having 2 to 4 carbon atoms and containing one or two unsaturated bonds per molecule. Specific examples of lower olefins include ethylene, propylene, butenes (1-butene, 2-butene, isobutene), and butadienes (1,2-butadiene and 1,3-butadiene).

[0052] In the present invention, "naphtha" refers to a liquid hydrocarbon composition derived from fossil fuels such as coal, crude oil (petroleum), and natural gas, or derived from biomass, containing 90 mass% or more of hydrocarbons having 5 to 12 carbon atoms, relative to 100% of the total mass of the naphtha. The hydrocarbons having 5 to 12 carbon atoms are mainly aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and styrene; aliphatic hydrocarbons such as normal pentane, 1-hexene, normal octane, 1-nonene, normal decane, and normal dodecane; and naphthenes such as methylcyclohexane and ethylcyclohexane. In the present invention, the content of hydrocarbons in the hydrocarbon composition can be measured using a known analytical method such as gas chromatography.

[0053] In this specification, the "hydrocarbon composition of the present invention," "method for producing a hydrocarbon composition of the present invention," "method for producing a lower olefin composition of the present invention," "method for producing a polyolefin polymer of the present invention," and "method for determining a hydrocarbon composition of the present invention" are collectively referred to as "the present invention."

[0054] [Hydrocarbon Composition] The hydrocarbon composition of the present invention is a hydrocarbon composition containing decomposition products of a chemically recycled feedstock, wherein the content of oxygen-containing compounds measured by elemental analysis is 900 ppm by mass or less in terms of oxygen atoms, and the chemically recycled feedstock comprises a polyolefin polymer and an oxygen-containing compound. When the content of the oxygen-containing compounds is 900 ppm by mass or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition, the amount of carbon monoxide (CO) produced by decomposition of the oxygen-containing compounds in a cracker facility during pyrolysis of the hydrocarbon composition to produce various lower olefins can be prevented from significantly increasing, thereby preventing the catalyst in the downstream hydrogenation tank from being poisoned. Furthermore, when the oxygen-containing compounds contain an organic acid, corrosion of the equipment can be prevented. Additionally, when the content of the oxygen-containing compounds is 900 ppm by mass or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition, the amount of methanol produced during pyrolysis is low, allowing a lower olefin composition with a low methanol content to be produced with a high olefin yield.

[0055] Furthermore, the hydrocarbon composition of the present invention preferably has an oxygen-containing compound content of 260 mass ppm or less in terms of oxygen atoms, as measured by gas chromatography, relative to the total mass of the hydrocarbon composition, since this more reliably suppresses the above-mentioned catalyst poisoning and equipment corrosion, reduces the amount of methanol produced in thermal cracking, and enables the production of a lower olefin composition having a low methanol content at a higher olefin yield.

[0056] The oxygen-containing compound in the present invention will be described in detail later.

[0057] One embodiment of the hydrocarbon composition of the present invention is a composition in which decomposition products derived from the thermal decomposition of chemically recycled raw materials account for 99 mass % or more of the hydrocarbon composition.

[0058] Another embodiment of the hydrocarbon composition of the present invention is a hydrocarbon-containing composition containing 14.0 mass% or more of hydrocarbons having 7 or more carbon atoms, relative to 100% of the total mass of the hydrocarbon composition. The hydrocarbons having 7 or more carbon atoms are mainly aromatic hydrocarbons such as ethylbenzene and styrene; aliphatic hydrocarbons such as normal heptane, normal octane, and normal decane; and naphthenes such as methylcyclohexane and ethylcyclohexane. The upper limit of the carbon number of these hydrocarbons is usually 15 or less. The hydrocarbon composition of the present invention may contain only one or more of these hydrocarbons having 7 or more carbon atoms. The hydrocarbon composition of the present invention has a content of these hydrocarbons having 7 or more carbon atoms of 14.0 mass% or more, relative to 100% of the total mass of the hydrocarbon composition. If the content of hydrocarbons having 7 or more carbon atoms is 14.0 mass% or more, lower olefins can be efficiently obtained when the hydrocarbon composition is thermally cracked in a naphtha cracker. Specifically, the lower olefin composition can be produced with a higher olefin yield. From this viewpoint, the lower limit of the content of hydrocarbons having 7 or more carbon atoms in the naphtha for producing lower olefins of the present invention is 14.0% by mass or more, preferably 16.0% by mass or more, more preferably 18.0% by mass or more, and even more preferably 20.0% by mass or more. On the other hand, if the proportion of high carbon atoms in the naphtha increases too much, there is a problem that the yield of lower olefins such as ethylene and propylene decreases. From this viewpoint, the upper limit of the content of hydrocarbons having 7 or more carbon atoms in the naphtha for producing lower olefins of the present invention is preferably 42.0% by mass or less, more preferably 38.0% by mass or less, and even more preferably 35.0% by mass or less. The above upper and lower limits can be combined arbitrarily. That is, the content of hydrocarbons having 7 or more carbon atoms in the naphtha for producing lower olefins of the present invention is preferably 14.0 mass% or more and 42.0 mass% or less, more preferably 16.0 mass% or more and 38.0 mass% or less, even more preferably 18.0 mass% or more and 35.0 mass% or less, and particularly preferably 20.0 mass% or more and 35.0 mass% or less.

[0059] In the hydrocarbon composition of the present invention, the upper limit of the content of olefinic compounds described below, measured using the PONA analysis method specified in JIS K 2536-2 (Petroleum Products - Component Testing Methods), is not particularly limited, and from the viewpoint of reducing the amount of coking produced during thermal cracking of the hydrocarbon composition, is preferably 180 ppm by mass or less, more preferably 160 ppm by mass or less, even more preferably 140 ppm by mass or less, particularly preferably 120 ppm by mass or less, and most preferably 110 ppm by mass or less. On the other hand, the lower limit of the content of the olefinic compounds is not particularly limited, and it is preferable that the composition is substantially free of olefinic compounds (0 ppm by mass). However, from the viewpoint of economic efficiency, such as the production costs required for separating and removing olefinic compounds, for example, a content of 0.1 ppm by mass or more, or even 1 ppm by mass or more, or 10 ppm by mass or more, relative to the total mass of the hydrocarbon composition, will sufficiently satisfy the required performance. The above upper and lower limits can be combined arbitrarily. Note that details of olefinic compounds will be described later.

[0060] The hydrocarbon composition obtained above, in which the content of olefinic compounds is 180 ppm by mass or less as measured by the PONA analysis method, can be obtained by the production method of the hydrocarbon composition of the present invention described below, particularly by carrying out a hydrogenation reaction and / or a dehydration reaction in the purification treatment in the production method of the hydrocarbon composition of the present invention.

[0061] Details of the analysis method using the above-mentioned PONA analysis method will be described later.

[0062] The hydrocarbon composition of the present invention is suitable as a cracker feedstock to be used in a waste plastic recycling plant for recycling waste plastics to produce lower olefins, particularly propylene.

[0063] Another embodiment of the hydrocarbon composition of the present invention is a hydrocarbon composition obtained by the method for producing a hydrocarbon composition of the present invention described below.

[0064] Another embodiment of the hydrocarbon composition of the present invention is a mixture obtained by mixing the decomposition products of waste plastics with at least one of other naphtha or crude oil prepared in advance. The mixture is subjected to distillation purification to recover a fraction corresponding to so-called naphtha, and the recovered fraction is fed to a naphtha cracker to obtain a lower olefin product.

[0065] "Waste plastic decomposition products" refers to decomposition oils obtained by reusing or recycling waste plastics, such as the plastic decomposition oils produced from substances obtained by decomposing the above-mentioned waste plastics, and the plastic decomposition refined oils obtained by refining the plastic decomposition oils. Specific examples include hydrocarbon compositions obtained by the hydrocarbon composition production method of the present invention described below. "Other naphthas prepared in advance" refers to naphthas derived from fossil fuels such as coal, crude oil (petroleum), and natural gas, or naphthas derived from biomass, excluding "waste plastic decomposition products." "Fossil fuel" refers to at least one selected from petroleum, coal, and natural gas. "Bio-derived naphtha" refers to naphtha derived from non-edible biomass and / or non-fossil fuels. "Non-edible biomass" refers to resources made from non-edible grasses and trees. Specific examples include, but are not limited to, cellulose, hemicellulose, lignin, paper, etc. obtained from woody biomass such as coniferous and broad-leaved trees; bioethanol and biodiesel obtained from herbaceous biomass such as corn and sugarcane stalks, soybeans, and rapeseed; and waste oil derived from plants. "Non-fossil fuel" refers to, for example, hydrogen or organic matter derived from plants or animals that is not derived from fossil fuels or non-edible biomass. Specific examples include, but are not limited to, methane and sugar ethanol obtained from firewood, charcoal, dried livestock manure, etc.

[0066] [Chemical Recycled Raw Material] The chemically recycled raw material in the present invention is a raw material used for producing the hydrocarbon composition of the present invention, and the hydrocarbon composition of the present invention includes a decomposition product obtained by thermally decomposing the chemically recycled raw material. The hydrocarbon composition of the present invention can also be obtained by purifying decomposition products such as plastic decomposition oils produced when chemically recycled raw materials such as waste plastics are thermally decomposed using the method for producing a hydrocarbon composition of the present invention described below.

[0067] The chemically recycled raw materials in the present invention can contain at least either waste plastics or biomass. When waste plastics or biomass are subjected to chemical recycling as chemically recycled raw materials, pyrolysis oil is produced, similar to fossil fuels such as petroleum, coal, and natural gas. As a result, consumption of natural resources can be reduced, and carbon dioxide emissions can be reduced compared to fossil fuels. In addition, the amount of waste can be reduced, thereby easing the burden on the environment. It goes without saying that the waste plastics may be plastics derived from biomass, or may contain compounds derived from biomass.

[0068] The chemically recycled raw material of the present invention may contain a polyolefin polymer, as described below, as waste plastic. The lower limit of the content of the polyolefin polymer contained in the chemically recycled raw material of the present invention is not particularly limited, and is typically 60% by mass or more, preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more, relative to 100% of the total mass of the chemically recycled raw material. On the other hand, the upper limit of the content of the polyolefin polymer is not particularly limited, and from the viewpoint of economic efficiency, such as the production cost required to purify the chemically recycled raw material, it is typically 99% by mass or less, preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less, and particularly preferably 94% by mass or less, relative to 100% of the total mass of the chemically recycled raw material. The above upper and lower limits can be combined arbitrarily. That is, the content of the polyolefin polymer contained in the chemically recycled raw material in the present invention is not particularly limited, and can be 60% by mass or more and 99% by mass or less, preferably 70% by mass or more and 98% by mass or less, more preferably 75% by mass or more and 97% by mass or less, even more preferably 80% by mass or more and 96% by mass or less, and particularly preferably 85% by mass or more and 94% by mass or less, relative to 100% by total mass of the chemically recycled raw material.

[0069] The chemically recycled raw material used in the present invention contains an oxygen-containing compound in addition to the polyolefin polymer. The lower limit of the content of the oxygen-containing compound in the chemically recycled raw material is not particularly limited, and is typically 200 ppm by mass or more, preferably 500 ppm by mass or more, more preferably 1000 ppm by mass or more, even more preferably 2000 ppm by mass or more, and particularly preferably 5000 ppm by mass or more, relative to 100% of the total mass of the chemically recycled raw material. On the other hand, the upper limit of the content of the oxygen-containing compound is not particularly limited, and is typically 200,000 ppm by mass or less, preferably 100,000 ppm by mass or less, more preferably 50,000 ppm by mass or less, even more preferably 20,000 ppm by mass or less, and particularly preferably 10,000 ppm by mass or less, relative to 100% of the total mass of the chemically recycled raw material. The above upper and lower limits can be combined arbitrarily. That is, the content ratio of oxygen-containing compounds contained in the chemically recycled raw material in the present invention is not particularly limited, and can be 200 mass ppm or more and 200,000 mass ppm or less, preferably 500 mass ppm or more and 100,000 mass ppm or less, more preferably 1,000 mass ppm or more and 50,000 mass ppm or less, even more preferably 2,000 mass ppm or more and 20,000 mass ppm or less, and particularly preferably 5,000 mass ppm or more and 10,000 mass ppm or less, relative to 100% of the total mass of the chemically recycled raw material.

[0070] [Oxygen-Containing Compound] The oxygen-containing compound of the present invention is one of the components of the chemically recycled raw material of the present invention, particularly when the chemically recycled raw material contains waste plastic. The oxygen-containing compound of the present invention is not particularly limited as long as it is a compound that contains an oxygen atom in the molecule, and examples thereof include polyamide resin, polyurethane resin, polyester resin, ethylene-vinyl acetate copolymer resin (EVA), ethylene-vinyl alcohol copolymer resin (EVOH), polyvinyl alcohol copolymer (PVA), paper, wood chips, and resin additives containing oxygen atoms.

[0071] [Olefinic Compound] The pyrolysis oil or hydrocarbon composition of the present invention may contain an olefinic compound. The olefinic compound of the present invention is an unsaturated hydrocarbon having 5 to 12 carbon atoms and containing one or two unsaturated bonds per molecule. Specific examples of the olefinic compound include cyclopentadiene, 2-methylcyclopentadiene, 2-methyl-1-pentene, 2,3-dimethyl-1-pentene, 1-hexene, 2-hexene, 2-methyl-2-hexene, cyclopentene, methylcyclopentene, ethylcyclopentene, dimethylcyclopentene, 1-heptene, 2-heptene, 1-octene, 2-octene, 1-nonene, 2-nonene, 1-decene, 2-decene, 1-undecene, 2-undecene, 1-dodecene, and 2-dodecene. The origin of the olefinic compound of the present invention is not particularly limited, and examples include compounds produced by the hydrogen elimination reaction of the pyrolysis product of the polyolefin polymer of the present invention.

[0072] [Oxygen-containing compound] The hydrocarbon composition of the present invention has a content of oxygen-containing compounds, measured by elemental analysis, of 900 mass ppm or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition. The oxygen-containing compounds in the present invention are oxygen-containing components contained in a pyrolysis oil obtained by pyrolyzing a chemically recycled feedstock containing the oxygen-containing compounds, and are derived from the oxygen-containing compounds.

[0073] The oxygen-containing compound in the present invention is not particularly limited, and examples thereof include oxygen-containing organic compounds having at least one oxygen atom selected from a hydroxyl group, a ketone group, a carboxyl group, an aldehyde group, and an ether group. Specific examples thereof include at least one selected from the group consisting of alcohol-based compounds described below, ketone-based compounds described below, carboxylic acid-based compounds described below, aldehyde-based compounds described below, and ether-based compounds described below.

[0074] The upper limit of the content of oxygen-containing compounds contained in the hydrocarbon composition of the present invention, as measured by elemental analysis, is 900 ppm by mass or less, preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, still more preferably 600 ppm by mass or less, even more preferably 500 ppm by mass or less, still more preferably 400 ppm by mass or less, and particularly preferably 300 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and of suppressing the amount of methanol produced in the resulting lower olefin composition.

[0075] On the other hand, the lower limit of the content of oxygen-containing compounds contained in the hydrocarbon composition of the present invention, as measured using elemental analysis, is not particularly limited, and it is acceptable for the composition to contain substantially no oxygen-containing compounds (0 ppm by mass). However, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content can usually be 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 1.0 ppm by mass or more, still more preferably 5.0 ppm by mass or more, even more preferably 10.0 ppm by mass or more, still more preferably 200 ppm by mass or more, and particularly preferably 250 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0076] The upper and lower limits can be combined arbitrarily. That is, the content of oxygen-containing compounds in the hydrocarbon composition of the present invention measured by elemental analysis is not particularly limited, and the hydrocarbon composition may be substantially free of oxygen-containing compounds (0 ppm by mass), or may be 0.1 ppm by mass or more and 900 ppm by mass or less, preferably 0.2 ppm by mass or more and 800 ppm by mass or less, more preferably 1.0 ppm by mass or more and 700 ppm by mass or less, still more preferably 5.0 ppm by mass or more and 600 ppm by mass or less, still more preferably 10.0 ppm by mass or more and 500 ppm by mass or less, still more preferably 200 ppm by mass or more and 400 ppm by mass or less, and particularly preferably 250 ppm by mass or more and 300 ppm by mass or less.

[0077] Furthermore, the hydrocarbon composition of the present invention can have an oxygen-containing compound content, measured by gas chromatography, of 260 mass ppm or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition.

[0078] The upper limit of the content of oxygen-containing compounds contained in the hydrocarbon composition of the present invention, as measured using gas chromatography, can be 260 ppm by mass or less, preferably 230 ppm by mass or less, more preferably 200 ppm by mass or less, even more preferably 150 ppm by mass or less, particularly preferably 120 ppm by mass or less, or even 100 ppm by mass or less, 80 ppm by mass or less, 50 ppm by mass or less, or 20 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and of suppressing the amount of methanol produced in the resulting lower olefin composition.

[0079] On the other hand, the lower limit of the content of oxygen-containing compounds contained in the hydrocarbon composition of the present invention, as measured using gas chromatography, is not particularly limited, and the hydrocarbon composition may be substantially free of oxygen-containing compounds (0 ppm by mass); however, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content can usually be 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.5 ppm by mass or more, even more preferably 1 ppm by mass or more, particularly preferably 2 ppm by mass or more, and may even be 5 ppm by mass or more, or 10 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0080] The above upper and lower limits can be combined arbitrarily. That is, the content of oxygen-containing compounds in the hydrocarbon composition of the present invention measured by gas chromatography is not particularly limited, and the hydrocarbon composition may be substantially free of oxygen-containing compounds (0 ppm by mass), or may be 0.1 ppm by mass or more and 260 ppm by mass or less, preferably 0.2 ppm by mass or more and 230 ppm by mass or less, more preferably 0.5 ppm by mass or more and 200 ppm by mass or less, still more preferably 1 ppm by mass or more and 150 ppm by mass or less, particularly preferably 2 ppm by mass or more and 120 ppm by mass or less, or even 5 ppm by mass or more and 100 ppm by mass or less, 10 ppm by mass or more and 80 ppm by mass or less, 10 ppm by mass or more and 50 ppm by mass or less, or 10 ppm by mass or more and 20 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0081] In the present invention, the method for controlling the content ratio of oxygen-containing compounds in the hydrocarbon composition measured using elemental analysis or gas chromatography is not particularly limited, and examples thereof include the production method of the hydrocarbon composition of the present invention described below, known extraction methods, known purification methods, and methods combining these, as well as a method of mixing two or more hydrocarbon compositions having different content ratios of oxygen-containing compounds, and a method of blending a hydrocarbon composition with diesel or the like to dilute it.

[0082] (Alcohol-Based Compound) The hydrocarbon composition of the present invention may contain an alcohol-based compound as a constituent of the oxygen-containing compound. The alcohol-based compound in the present invention is not particularly limited and is an alcohol having one or more hydroxyl groups in the molecule, and specific examples thereof include primary alcohols having 1 to 6 carbon atoms such as methanol, ethanol, propyl alcohol, butanol, pentanol, and hexanol; secondary alcohols having 3 to 8 carbon atoms such as phenol, 2-butanol, 2-hexanol, and 1-phenylethanol; and tertiary alcohols having 4 to 9 carbon atoms such as tert-butyl alcohol, 2-methyl-2-butanol, 2-methyl-2-pentanol, 1-methylcyclohexanol, and 2-phenyl-2-propanol.

[0083] The upper limit of the content of alcohol-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and suppressing the amount of methanol produced in the resulting lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography is preferably 160 ppm by mass or less, more preferably 80 ppm by mass or less, even more preferably 40 ppm by mass or less, even more preferably 30 ppm by mass or less, still more preferably 20 ppm by mass or less, and even more preferably 10 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0084] On the other hand, the lower limit of the content of alcohol-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and the hydrocarbon composition may contain substantially no alcohol-based compounds (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography is usually 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.4 ppm by mass or more, even more preferably 0.8 ppm by mass or more, and particularly preferably 1.6 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0085] The above upper and lower limits can be combined in any way.

[0086] (Ketone Compound) The hydrocarbon composition of the present invention may contain a ketone compound as a constituent of the oxygen-containing compound. The ketone compound in the present invention is not particularly limited, and is a ketone having one or more carbonyl groups in the molecule, such as acetone, methyl ethyl ketone, 2-pentanone, cyclopentanone, and acetophenone.

[0087] The upper limit of the content of ketone compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and of suppressing the amount of methanol produced in the resulting lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition, is preferably 70 ppm by mass or less, more preferably 40 ppm by mass or less, even more preferably 20 ppm by mass or less, still more preferably 18 ppm by mass or less, even more preferably 15 ppm by mass or less, still more preferably 12 ppm by mass or less, and particularly more preferably 10 ppm by mass or less.

[0088] On the other hand, the lower limit of the content of ketone compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and the hydrocarbon composition may be substantially free of ketone compounds (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography is usually 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.4 ppm by mass or more, even more preferably 0.8 ppm by mass or more, and particularly preferably 1.6 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0089] The above upper and lower limits can be combined in any way.

[0090] (Carboxylic Acid Compound) The hydrocarbon composition of the present invention may contain a carboxylic acid compound as a constituent of the oxygen-containing compound. The carboxylic acid compound in the present invention is not particularly limited, and is a carboxylic acid having one or more carboxyl groups in the molecule, such as acetic acid, propionic acid, butyric acid, isobutyric acid, enanthic acid, and benzoic acid.

[0091] The upper limit of the content of carboxylic acid compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and suppressing the amount of methanol produced in the resulting lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition, is preferably 30 ppm by mass or less, more preferably 20 ppm by mass or less, even more preferably 15 ppm by mass or less, still more preferably 10 ppm by mass or less, even more preferably 5 ppm by mass or less, and even preferably 3.0 ppm by mass or less, 2.5 ppm by mass or less, 2.0 ppm by mass or less, 1.5 ppm by mass or less, or 1.1 ppm by mass or less.

[0092] On the other hand, the lower limit of the content of carboxylic acid compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and the hydrocarbon composition may be substantially free of carboxylic acid compounds (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography is usually 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.4 ppm by mass or more, even more preferably 0.8 ppm by mass or more, and particularly preferably 1.6 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0093] The above upper and lower limits can be combined in any way.

[0094] (Aldehyde Compound) The hydrocarbon composition of the present invention may contain an aldehyde compound as a constituent of the oxygen-containing compound. The aldehyde compound in the present invention is not particularly limited, and is an aldehyde having one or more formyl groups in the molecule, such as acetaldehyde, propionaldehyde, isovaleraldehyde, and butyraldehyde.

[0095] The upper limit of the content of aldehyde compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and suppressing the amount of methanol produced in the resulting lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, is preferably 30 ppm by mass or less, more preferably 25 ppm by mass or less, even more preferably 20 ppm by mass or less, still more preferably 15 ppm by mass or less, even more preferably 10 ppm by mass or less, still more preferably 5 ppm by mass or less, and particularly more preferably 2.5 ppm by mass or less.

[0096] On the other hand, the lower limit of the content of aldehyde compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and the hydrocarbon composition may be substantially free of aldehyde compounds (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography can usually be set to 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.4 ppm by mass or more, even more preferably 0.5 ppm by mass or more, still more preferably 0.8 ppm by mass or more, still more preferably 1.0 ppm by mass or more, even more preferably 1.6 ppm by mass or more, and particularly more preferably 2.0 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0097] The above upper and lower limits can be combined in any way.

[0098] (Ether Compound) The hydrocarbon composition of the present invention may contain an ether compound as a constituent of the oxygen-containing compound. The ether compound in the present invention is not particularly limited, and specific examples thereof include asymmetric ethers having an asymmetric structure with respect to the oxygen atom constituting the ether bond (hereinafter, sometimes referred to as "ether oxygen atom") and symmetric ethers having a symmetric structure, preferably asymmetric ethers.

[0099] For example, as an asymmetric ether having an asymmetric structure with respect to the ether oxygen atom, 2-methoxybutane (CH ３ CH ２ CH (CH ３ )-O-CH ３ ), methoxycyclopentane (C ５ H ９ -O-CH ３ ), 1-methoxypropane (CH ３ CH ２ CH ２ -O-CH ３ ), t-amyl methyl ether (C(CH ３ ) ２ (CH ２ CH ３ )-O-CH ３), sec-butyl methyl ether (CH(OCH ３ ) (CH ２ CH ３ )-O-CH ３ ), cyclopentyl methyl ether (C ５ H ９ -O-CH ３ ) etc.

[0100] On the other hand, dimethyl ether (CH ３ -O-CH ３ ), diethyl ether (CH ３ -CH ２ -O-CH ２ -CH ３ ), diisopropyl ether ((CH ３ ) ２ CH-O-CH(CH ３ ) ２ ), dipropyl ether (CH ３ -CH ２ -CH ２ -O-CH ２ -CH ２ -CH ３ ) are listed.

[0101] Among the above-mentioned ether-based compounds, the asymmetric ethers can be used from the viewpoint of being able to effectively reduce the content of produced methanol in the resulting lower olefin composition in the thermal cracking step of a hydrocarbon composition obtained from waste plastics. Among these, ether-based compounds in which one of the two carbon atoms bonded to the oxygen atom constituting the ether bond of the ether-based compound is a carbon atom of a methyl group, or monoethers having only one ether oxygen atom in the molecule are preferred.

[0102] The upper limit of the content of ether-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and suppressing the amount of methanol produced in the resulting lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, is preferably 45 ppm by mass or less, more preferably 35 ppm by mass or less, even more preferably 25 ppm by mass or less, still more preferably 20 ppm by mass or less, even more preferably 10 ppm by mass or less, or even 5 ppm by mass or less, 4 ppm by mass or less, 3 ppm by mass or less, 2 ppm by mass or less, or 1 ppm by mass or less.

[0103] On the other hand, the lower limit of the content of ether compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and it may be that the composition contains substantially no ether compounds (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography can usually be 0.1 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition, preferably 0.2 ppm by mass or more, more preferably 0.4 ppm by mass or more, even more preferably 0.5 ppm by mass or more, even more preferably 0.6 ppm by mass or more, and even more preferably 0.8 ppm by mass or more. 1.0 ppm by mass or more is even more preferred, and 2.0 ppm by mass or more is particularly preferred.

[0104] The above upper and lower limits can be combined in any way.

[0105] The upper limit of the total content of the alcohol-based compounds, the ketone-based compounds, the carboxylic acid-based compounds, the aldehyde-based compounds, and the ether-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further thermally cracking a hydrocarbon composition obtained by thermally cracking waste plastics and purifying the resulting plastic cracked oil, and suppressing the amount of methanol produced in the lower olefin composition, the content of oxygen-containing organic compounds measured using gas chromatography can be 260 ppm by mass or less, preferably 230 ppm by mass or less, more preferably 200 ppm by mass or less, even more preferably 160 ppm by mass or less, still more preferably 150 ppm by mass or less, still more preferably 120 ppm by mass or less, still more preferably 100 ppm by mass or less, or even 50 ppm by mass or less, 20 ppm by mass or less, or 10 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition.

[0106] On the other hand, the lower limit of the total content of the alcohol-based compounds, the ketone-based compounds, the carboxylic acid-based compounds, the aldehyde-based compounds, and the ether-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and may be substantially free of any of them (0 ppm by mass). Alternatively, from the viewpoint of economic efficiency, such as the production costs required for purifying and separating the hydrocarbon composition, the content of oxygen-containing organic compounds measured using gas chromatography, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition, can usually be 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, more preferably 0.3 ppm by mass or more, even more preferably 0.5 ppm by mass or more, still more preferably 1.0 ppm by mass or more, still more preferably 2.0 ppm by mass or more, even more preferably 3.0 ppm by mass or more, and particularly more preferably 5.0 ppm by mass or more.

[0107] The above upper and lower limits can be combined in any way.

[0108] [Method for Producing a Hydrocarbon Composition] The method for producing a hydrocarbon composition of the present invention is described below. The method for producing a hydrocarbon composition of the present invention is a method for producing a hydrocarbon composition, comprising purifying a pyrolysis oil such as plastic cracking oil produced by the pyrolysis of a chemically recycled feedstock such as waste plastics, to obtain a hydrocarbon composition, wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound, and the purification comprises subjecting the oxygen-containing compound in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst).

[0109] For the reasons described above, in the method for producing a hydrocarbon composition of the present invention, it is preferable to carry out the hydrogenation reaction or the dehydration reaction in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, measured using elemental analysis, is 900 ppm by mass or less, calculated as oxygen atoms. Furthermore, for the reasons described above, in the method for producing a hydrocarbon composition of the present invention, the hydrogenation reaction or the dehydration reaction can be carried out in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, measured using gas chromatography, is 260 ppm by mass or less, preferably 160 ppm by mass or less, calculated as oxygen atoms. Note that the oxygen-containing compound in the method for producing a hydrocarbon composition of the present invention has the same meaning as the oxygen-containing compound in the hydrocarbon composition of the present invention, and the preferred range is also the same. The oxygen-containing compound in the method for producing a hydrocarbon composition of the present invention has the same meaning as the oxygen-containing compound in the hydrocarbon composition of the present invention, and the preferred range is also the same.

[0110] In the method for producing a hydrocarbon composition of the present invention, the oxygen-containing compound may specifically comprise at least one compound selected from the group consisting of an alcohol-based compound, a ketone-based compound, a carboxylic acid-based compound, an aldehyde-based compound, and an ether-based compound. Note that the alcohol-based compound, ketone-based compound, carboxylic acid-based compound, aldehyde-based compound, and ether-based compound in the method for producing a hydrocarbon composition of the present invention are synonymous with the alcohol-based compound, ketone-based compound, carboxylic acid-based compound, aldehyde-based compound, and ether-based compound in the hydrocarbon composition of the present invention, respectively.

[0111] [Pyrolysis Oil] The pyrolysis oil in the present invention is a pyrolysis oil produced by the thermal decomposition of a chemically recycled feedstock. In the present invention, the pyrolysis oil is obtained by thermally decomposing the chemically recycled feedstock. While known methods can be used for the pyrolysis method, it is preferable to obtain a pyrolysis product from the chemically recycled feedstock by thermal decomposition without a catalyst. This configuration reduces catalyst costs and eliminates the need for a catalyst separation process, allowing for more economical production of high-purity pyrolysis oil.

[0112] In the present invention, the thermal cracking oil is preferably plastic cracking oil. Plastic cracking oil is cracking oil produced by the thermal cracking of waste plastic, and is usually cracking oil made from discarded plastic. The plastic cracking oil in the present invention may be a distillate of a naphtha-equivalent fraction obtained by distilling and refining the cracking oil produced by the thermal cracking of waste plastic. In the present invention, the method for thermally cracking waste plastic is not particularly limited, and known methods described, for example, in JP-A-9-235563 and JP-A-10-088149 can be used.

[0113] The raw material of waste plastics (hereinafter referred to as "waste plastic raw material") that can be used in the method for producing a hydrocarbon composition of the present invention is not particularly limited, and examples thereof include known thermoplastic resins, known thermosetting resins, and known synthetic rubbers.

[0114] Examples of thermoplastic resins include polyolefins (PO) such as polyethylene (PE) and polypropylene (PP); styrene-based resins such as polystyrene (PS) and high impact polystyrene (HIPS); nitrogen-containing resins such as polyamide resin (also known as "nylon") and ABS resin; resins containing a copolymer of an olefin monomer and a small proportion of another monomer, such as ethylene-vinyl acetate copolymer resin (EVA), ethylene-vinyl alcohol copolymer resin (EVOH), and polyvinyl-alcohol copolymer (PVA); chlorine-containing resins such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC); and polycarbonate (PC)-based resins.

[0115] Examples of the thermosetting resin include phenol resin, melamine resin, urea resin, alkyd resin, and polyurethane (PU).

[0116] Examples of synthetic rubbers include 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.

[0117] These waste plastic raw materials may be used alone or in combination of two or more.

[0118] In the method for producing a hydrocarbon composition of the present invention, particularly preferred waste plastic raw materials are polyolefins such as polyethylene and polypropylene; and olefin resin compositions containing two or more polyolefin polymers as main components.

[0119] The biomass feedstock applicable to the method for producing a hydrocarbon composition of the present invention is not particularly limited, and may be a compound derived from a known non-edible biomass and / or a compound derived from a known non-fossil fuel. The use of a biomass feedstock can contribute to the achievement of the Sustainable Development Goals (SDGs). Specifically, a single biomass-derived compound or a mixture containing a biomass-derived compound and a fossil fuel-derived compound can be used.

[0120] In the present invention, the compound derived from a fossil fuel refers to at least one compound selected from the group consisting of a compound derived from petroleum, a compound derived from coal, and a compound derived from natural gas.

[0121] The plastic cracked oil must have specific distillation properties, with a 95% distillation temperature of 100 to 600°C, particularly preferably above 300°C, and even more preferably above 400°C, and an initial boiling point of 200°C or less, particularly preferably 100°C or less. Furthermore, for the distillate of the naphtha-equivalent fraction obtained by distilling and refining the plastic cracked oil produced by the thermal cracking of the waste plastic, the 95% distillation temperature is preferably 100 to 400°C, particularly preferably 150 to 250°C, and the initial boiling point is preferably 200°C or less, particularly preferably 100°C or less.

[0122] The pyrolysis oil of the present invention contains oxygen-containing compounds. In the present invention, it is preferable to reduce the amount of oxygen-containing compounds in the pyrolysis oil by hydrogenation and dehydration. The lower limit of the content of oxygen-containing compounds in the pyrolysis oil (reducing the amount of oxygen-containing compounds in the pyrolysis oil before reduction by hydrogenation and dehydration) is typically 1500 mass ppm or more in terms of oxygen atoms, relative to 100% of the total mass of the pyrolysis oil, and may even be 2000 mass ppm or more, 3000 mass ppm or more, 3500 mass ppm or more, or 4000 mass ppm or more. On the other hand, the upper limit of the content of the oxygen-containing compounds is typically 30,000 mass ppm or less in terms of oxygen atoms, relative to 100% of the total mass of the pyrolysis oil, and may even be 10,000 mass ppm or less, 7000 mass ppm or less, 6000 mass ppm or less, or 5000 mass ppm or less. The above upper and lower limits can be combined arbitrarily. That is, the content ratio of the oxygen-containing compounds contained in the pyrolysis oil in the present invention is not particularly limited, and may be, for example, 1,500 ppm by mass to 30,000 ppm by mass, 2,000 ppm by mass to 10,000 ppm by mass, 3,000 ppm by mass to 7,000 ppm by mass, 3,500 ppm by mass to 6,000 ppm by mass, or 4,000 ppm by mass to 5,000 ppm by mass, calculated as oxygen atoms, relative to 100% by total mass of the pyrolysis oil.

[0123] [Refining Treatment] The method for producing a hydrocarbon composition of the present invention includes purifying the above-mentioned pyrolysis oil to obtain a hydrocarbon composition. In the refining treatment, the pyrolysis oil such as the plastic cracking oil is subjected to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst described below and a dehydration catalyst described below, to obtain a hydrocarbon composition. Pyrolysis oil usually contains oxygen-containing compounds, and it is preferable to reduce the amount of oxygen-containing compounds in the pyrolysis oil by the hydrogenation reaction and the dehydration reaction.

[0124] In the purification process, it is preferable that the hydrogenation catalyst and the dehydration catalyst exist in an independent state, from the viewpoint of efficiently removing oxygen-containing compounds from the thermal cracking oil such as the plastic cracking oil. "Existing in an independent state" means that the hydrogenation catalyst and the dehydration catalyst exist in a reaction system in a physically separable state. Specifically, "existing in an independent state" does not mean a state in which the dehydration catalyst is supported on a carrier having hydrogenation catalytic ability, or a state in which the hydrogenation catalyst is supported on a carrier having dehydration catalytic ability.

[0125] In the present invention, it is preferable to convert at least a portion of the oxygen-containing compounds in the pyrolysis oil to paraffins through the hydrogenation and dehydration reactions. Paraffins are converted from, for example, alcohol compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds. As described below, in the refining process, oxygen-containing compounds contained in pyrolysis oil, such as plastic cracking oil, are converted into corresponding alcohol compounds through a hydrogenation reaction. The alcohol compounds are then converted into corresponding unsaturated hydrocarbon compounds through a dehydration reaction, and the unsaturated hydrocarbon compounds are further converted into corresponding saturated hydrocarbon compounds through a hydrogenation reaction. In the production method of the present invention, the hydrogenation catalyst and the dehydration catalyst are present in a mixed state, allowing the hydrogenation and dehydration reactions to proceed in concert, thereby efficiently reducing the oxygen-containing compounds in the resulting hydrocarbon composition. Furthermore, since the hydrogenation catalyst and the dehydration catalyst are present in an independent state, the diffusion rate limitation of the target substance is eliminated, compared to a catalyst configuration in which, for example, the dehydration catalyst is a carrier and the hydrogenation catalyst is a supported material, and it is presumed that the reaction efficiency of the hydrogenation reaction and / or the dehydration reaction will be improved.

[0126] In the present invention, it is preferable to carry out the hydrogenation reaction and / or the dehydration reaction in the purification treatment so that the content of olefinic compounds in the obtained hydrocarbon composition, as measured using the PONA analysis method, is 180 mass ppm or less. By configuring in this way, the effect of reducing the amount of coking produced during thermal cracking of the hydrocarbon composition tends to be more effectively exerted. The preferred range of the content of olefinic compounds in the hydrocarbon composition, as measured using the PONA analysis method, is the same as the preferred range of the content of olefinic compounds in the hydrocarbon composition of the present invention described above.

[0127] One specific embodiment of "existing in an independent state" means that the hydrogenation catalyst and the dehydration catalyst are present in a mixed state in the reaction system, but are physically separable. Alternatively, another specific embodiment of "existing in an independent state" means that a layer containing the hydrogenation catalyst and a layer containing the dehydration catalyst are arranged in series in the reaction system. More specifically, there are mentioned embodiments in which the layer containing the hydrogenation catalyst and the layer containing the dehydration catalyst are arranged in succession in one reactor, and embodiments in which the reactor containing the hydrogenation catalyst and the reactor containing the dehydration catalyst are arranged in succession, directly or indirectly connected to each other.

[0128] <Hydrogenation Catalyst> In the method for producing a hydrocarbon composition of the present invention, the hydrogenation catalyst is a catalyst used in the hydrogenation reaction of a thermal cracking oil such as a plastic cracking oil during the refining treatment, and specifically, a catalyst used in either of the following reactions (1) or (2): (1) Hydrogenating oxygen-containing compounds contained in the thermal cracking oil such as a plastic cracking oil to convert them into corresponding alcohol compounds; (2) Hydrogenating unsaturated hydrocarbon compounds produced in the dehydration reaction described below to convert them into corresponding saturated hydrocarbon compounds.

[0129] The hydrogenation catalyst used in the method for producing a hydrocarbon composition of the present invention is not particularly limited, and any known hydrogenation catalyst used in catalytic hydrorefining of petroleum can be used.

[0130] The hydrogenation catalyst used in the present invention is preferably a known hydrogenation catalyst containing at least one metal selected from transition metals belonging to Groups 8 to 10 of the periodic table, from the viewpoint of efficiently hydrogenating oxygen-containing compounds in thermal cracking oil such as the plastic cracking oil. Examples of transition metals belonging to Group 8 of the periodic table include ruthenium. Examples of transition metals belonging to Group 9 of the periodic table include cobalt. Examples of transition metals belonging to Group 10 of the periodic table include nickel, palladium, and platinum. The transition metals can be used alone or in combination of two or more.

[0131] More specifically, examples of the hydrogenation catalyst used in the present invention include known molybdenum-based hydrogenation catalysts such as nickel-molybdenum catalysts (NiMo catalysts) and cobalt-molybdenum catalysts (CoMo catalysts), which are prepared by supporting molybdenum on a known carrier and adding a transition metal belonging to Groups 8 to 10 of the periodic table, such as nickel or cobalt, to activate the molybdenum; transition metal oxide catalysts containing such transition metals as molybdenum oxide, nickel oxide, and cobalt oxide; and noble metal catalysts such as ruthenium-based catalysts, palladium-based catalysts, and platinum-based catalysts. Among these, from the viewpoint of catalytic activity, Ni-based catalysts, ruthenium-based catalysts, and palladium-based catalysts are preferred, with Ni-based catalysts and ruthenium being more preferred. The above-mentioned hydrogenation catalysts can be used alone or in combination of two or more.

[0132] The form of the hydrogenation catalyst in the present invention is not particularly limited, but a solid catalyst or a complex catalyst is preferred, with a solid catalyst being preferred because it allows the production of a hydrocarbon composition of higher quality.

[0133] Furthermore, it is preferable to use a porous material with a large surface area, such as alumina, silica, activated carbon, etc., as the support for these hydrogenation catalysts. When the hydrogenation catalyst is a catalyst supported on a support, for example, alumina or silica as the support is preferable as a dehydration catalyst described below, but if alumina or silica is used as a dehydration catalyst in an independent state apart from the alumina or silica as the support for the hydrogenation catalyst, this state can also be said to be "existing in an independent state" in the present invention.

[0134] <Dehydration Catalyst> In the method for producing a hydrocarbon composition of the present invention, the dehydration catalyst (excluding the hydrogenation catalyst) is a catalyst used in the dehydration reaction of thermal cracking oil such as plastic cracking oil during the refining treatment, and specifically, a catalyst used in the reaction (3) below.

[0135] (3) The alcohol-based compounds produced by the hydrogenation reaction or the alcohol-based compounds already contained in the thermal cracking oil such as the plastic cracking oil are subjected to a dehydration reaction to be converted into the corresponding unsaturated hydrocarbon compounds.

[0136] The dehydration catalyst used in the method for producing a hydrocarbon composition of the present invention is not particularly limited, and any known dehydration catalyst used in the petrochemical field can be used.

[0137] Specific examples of the dehydration catalyst include known dehydration catalysts such as solid acids such as silica, alumina, silica-alumina, and zeolite, and transition metal oxide catalysts such as molybdenum oxide and tungsten oxide. Among these, from the viewpoint of catalytic activity, at least one selected from the group consisting of silica, alumina, silica-alumina, and zeolite is preferred, with silica-alumina and zeolite being more preferred. In order to avoid isomerization reactions, the dehydration catalyst may be one whose acidity is adjusted by adding an alkaline component. The above-mentioned dehydration catalysts can be used alone or in combination of two or more.

[0138] The form of the dehydration catalyst is not particularly limited, but a solid catalyst or a complex catalyst is preferred, with a solid catalyst being preferred since it allows the production of a hydrocarbon composition of higher quality.

[0139] The reaction system (apparatus) for the hydrogenation reaction and the dehydration reaction in the purification treatment of the present invention is not particularly limited, and the reaction can be carried out using a known reaction system (apparatus), such as a tank-type batch reaction system, a fixed-bed system, a tubular continuous reaction system, a fluidized-bed system, or a moving-bed system.

[0140] In the present invention, the form in which the hydrogenation catalyst and the dehydration catalyst are present is not particularly limited as long as they "exist in an independent state." It is preferred that the hydrogenation catalyst and the dehydration catalyst are present in a mixed state in the reaction system, and that the hydrogenation reaction and the dehydration reaction (hereinafter referred to as "hydrogenation-dehydration reaction") proceed in the same reaction apparatus (reactor).

[0141] The reaction conditions for the hydrogenation and dehydration reaction are not particularly limited, and the following conditions can be used.

[0142] <Conditions for Hydrogenation and Dehydration Reactions> The hydrogen pressure during the hydrogenation and dehydration reactions is not particularly limited and is usually 1 to 10 MPa, more preferably 2 to 6 MPa. If the hydrogen pressure (defined as total pressure (pressure of the high-pressure separator at the outlet of the reaction tower) × hydrogen concentration in the supplied hydrogen gas) is too low, there is a problem that the reaction efficiency of the hydrogenation and dehydration reactions of the oxygen-containing compound decreases. On the other hand, the higher the hydrogen pressure, the more efficiently the hydrogenation and dehydration reactions proceed. However, there is a problem that the heat generated by the hydrogenation reaction becomes excessive, making it difficult to control the hydrogenation reaction and increasing the equipment costs for heat removal.

[0143] The reaction temperature is not particularly limited, but is usually 150 to 450°C, and more preferably 200 to 350°C. By setting the reaction temperature at 200°C or higher, the hydrogenation reaction and dehydration reaction tend to proceed more effectively, while by setting the reaction temperature at 350°C or lower, the occurrence of excessive cracking of hydrocarbons tends to be effectively suppressed. Note that when the reactor is a tubular reactor (reaction tower), the reaction temperature refers to the temperature defined by the catalyst weight average temperature. Furthermore, the liquid hourly space velocity (LHSV) is not particularly limited, but is usually 0.1 to 10 h －１ It is preferable to set the temperature to 0.5 to 5.0 h. －１ It is more preferable to set the temperature to 0.5 to 2.0 h. －１ It is more preferable that the liquid hourly space velocity is 0.5 h －１ If the temperature is lower than 2.0 h, excessive cracking of hydrocarbons may occur. －１ If the ratio is higher than 1000 Nm, the hydrogenation reaction and dehydration reaction may not proceed sufficiently. Furthermore, the hydrogen / thermal cracking oil ratio (preferably the hydrogen / plastic cracking oil ratio) is not particularly limited, and is usually 20 to 1000 Nm ３ -H ２ / kL-pyrolysis oil is preferred, and 200 to 500 Nm ３ It is more preferable to set the hydrogen / thermal cracking oil ratio to 200 to 500 Nm ３ By setting the hydrogen / oil ratio at 1 / kL, the hydrogen required for the reaction can be supplied and catalyst deterioration can be suppressed. Note that the hydrogen / oil ratio is based on the pumped volume of pyrolysis oil (kL: kiloliters).

[0144] The lower limit of the mass ratio of the hydrogenation catalyst to the dehydration catalyst used in the purification treatment is not particularly limited, and from the viewpoint of reducing olefinic compounds in the pyrolysis oil, it is preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.7 or more, and particularly preferably 0.8 or more. On the other hand, the upper limit of the mass ratio is not particularly limited, and from the viewpoint of reducing oxygenated compounds in the pyrolysis oil, it is preferably 90 or less, more preferably 30 or less, even more preferably 10 or less, and particularly preferably 3.0 or less. The above upper and lower limits can be arbitrarily combined. For example, the mass ratio of the hydrogenation catalyst to the dehydration catalyst is preferably 0.5 or more and 90 or less, more preferably 0.6 or more and 30 or less, even more preferably 0.7 or more and 10 or less, and particularly preferably 0.8 or more and 3.0 or less.

[0145] The lower limit of the total mass of the dehydration catalyst and hydrogenation catalyst used in the purification treatment is not particularly limited, but from the viewpoint of reducing the content of oxygen-containing compounds and olefinic compounds in the resulting hydrocarbon composition, it is preferably 300 mass% or more, more preferably 500 mass% or more, and even more preferably 600 mass% or more, based on the oxygen atom equivalent of the oxygen-containing compounds in the pyrolysis oil. On the other hand, the upper limit of the total mass of the dehydration catalyst and hydrogenation catalyst is not particularly limited, but from the viewpoint of reducing the contamination of the catalyst components in the resulting hydrocarbon composition and reducing the raw material cost of the catalyst, it is more preferably 2000 mass% or less, even more preferably 1500 mass% or less, based on the oxygen atom equivalent of the oxygen-containing compounds in the pyrolysis oil. The above upper and lower limits can be arbitrarily combined. For example, the total mass of the dehydration catalyst and hydrogenation catalyst is preferably 300 mass% or more, more preferably 300 mass% to 2000 mass%, and even more preferably 600 mass% to 1500 mass%, based on the oxygen atom equivalent of the oxygen-containing compounds in the pyrolysis oil.

[0146] In the method for producing a hydrocarbon composition of the present invention, the hydrocarbon composition obtained by refining a thermal cracking oil such as a plastic cracking oil is then subjected to a process similar to that of known naphtha cracking, thereby converting it into ethylene, propylene, 1-butene, butadiene, isoprene, benzene, toluene, xylene, styrene, and other unsaturated hydrocarbons that are useful as petrochemical feedstocks. In particular, ethylene and propylene are relatively inexpensive and have excellent properties that make them suitable as feedstocks for a wide range of products.

[0147] [Method for producing a lower olefin composition] The method for producing a lower olefin composition of the present invention includes a step of cracking the hydrocarbon composition of the present invention. Alternatively, the method for producing a lower olefin composition of the present invention includes a step of obtaining the hydrocarbon composition of the present invention by the method for producing a hydrocarbon composition of the present invention, and cracking the obtained hydrocarbon composition (hereinafter referred to as "the hydrocarbon composition obtained by the production method of the present invention").

[0148] More specifically, the method for producing a lower olefin composition of the present invention comprises purifying a pyrolysis oil produced by thermal decomposition of a chemically recycled feedstock to obtain a hydrocarbon composition, wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound, and in the purification process, the oxygen-containing compound in the pyrolysis oil is subjected to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst), to obtain the hydrocarbon composition, and the method comprises introducing the hydrocarbon composition into a naphtha cracker and thermally decomposing it to obtain the lower olefin composition.

[0149] Hereinafter, the "hydrocarbon composition of the present invention" and the "hydrocarbon composition obtained by the production method of the present invention" will be collectively referred to as the "hydrocarbon composition of the present invention."

[0150] A lower olefin composition containing lower olefins and methanol is produced by thermally cracking the hydrocarbon composition of the present invention. In this method for producing a lower olefin composition, by using the hydrocarbon composition of the present invention as a cracker feedstock to be subjected to thermal cracking, as described above, the amount of methanol produced can be significantly reduced and catalyst poisoning in a hydrogenation tank and corrosion of equipment can be suppressed.

[0151] The method for producing a lower olefin composition of the present invention can be carried out in a conventional manner, except that the hydrocarbon composition of the present invention is used. That is, the hydrocarbon composition of the present invention (hereinafter sometimes simply referred to as the "hydrocarbon composition") is thermally decomposed (steam cracked) in the presence of steam at a temperature of 700 to 1000°C to obtain a lower olefin composition.

[0152] Among the conditions for thermal decomposition, the ratio of the hydrocarbon composition to the water vapor is preferably 20 to 100 parts by mass, more preferably 30 to 70 parts by mass, and particularly preferably 35 to 60 parts by mass, of water vapor per 100 parts by mass of the hydrocarbon composition. If the amount of water vapor is less than 20 parts by mass, there is a tendency for a large amount of carbonaceous material to be deposited on the piping for carrying out the decomposition reaction installed in the thermal decomposition furnace. On the other hand, if the amount of water vapor exceeds 100 parts by mass, the amount of heat given to the water vapor increases, resulting in an excessive energy load on the device.

[0153] The reaction temperature for thermal cracking is usually 700 to 1000°C, preferably 750 to 950°C. If the reaction temperature is less than 700°C, the thermal cracking of the hydrocarbon composition does not proceed sufficiently, resulting in a decrease in the yield of the target lower olefins. If the reaction temperature exceeds 1000°C, the thermal cracking of the hydrocarbon composition becomes excessive, increasing the generation of undesirable by-products such as methane, and tending to decrease the yield of the target lower olefins.

[0154] The reaction time for thermal cracking is preferably 0.01 to 1 second, more preferably 0.04 to 0.7 seconds. If the reaction time is less than 0.01 second, the thermal cracking of the hydrocarbon composition does not proceed sufficiently, and the yield of the target lower olefins tends to decrease. If the reaction time exceeds 1 second, the thermal cracking of the hydrocarbon composition becomes excessive, and the generation of undesirable by-products such as methane increases, tending to decrease the yield of the target lower olefins.

[0155] The reaction pressure for the thermal decomposition is preferably 0.01 to 1.5 MPa (gauge pressure), more preferably 0.05 to 0.5 MPa (gauge pressure), and even more preferably 0.07 to 0.2 MPa (gauge pressure).

[0156] The reaction product that has left the pyrolysis reaction zone can be rapidly cooled to prevent excessive decomposition. The cooling temperature is not particularly limited, and is preferably 200 to 700°C, more preferably 250 to 650°C, when carried out on an industrial scale. When carried out on a small scale such as in a pilot plant or laboratory, the cooling temperature is preferably 0 to 100°C, more preferably 3 to 40°C.

[0157] The reaction product containing lower olefins thus obtained can be purified, fractionated, and the like according to conventional methods. As a result, lower olefins such as ethylene, propylene, butene, and butadiene, aromatic hydrocarbons, and other hydrocarbons are obtained, respectively. Saturated hydrocarbons such as ethane and propane can be recovered and subjected to thermal cracking again. Of the lower olefins, butene and butadiene are usually obtained as a mixture with butane. Therefore, butadiene is isolated by solvent extraction in a separate process. The mixture of butene and butane remaining after extraction is preferably utilized and fractionated in a separate process by polymerization, rectification, or the like.

[0158] As described above, methanol adversely affects polymerization catalysts used in polymerizing lower olefins. The lower olefin composition obtained by thermal cracking the hydrocarbon composition of the present invention, which has a reduced oxygen-containing compound content, has a reduced methanol content. Therefore, this composition is effective for producing lower olefins such as propylene.

[0159] According to the method for producing a lower olefin composition using the hydrocarbon composition of the present invention, it is possible to produce a lower olefin composition which contains lower olefins and in which the production of methanol is suppressed, i.e., which has a low methanol content.

[0160] The method for producing a lower olefin composition of the present invention can be used to produce a propylene composition containing propylene and methanol. More specifically, the method for producing a lower olefin composition of the present invention can be used to produce a propylene composition that contains propylene and in which methanol production is suppressed, i.e., a propylene composition with a low methanol content.

[0161] As described above, methanol adversely affects a polymerization catalyst when polymerizing a lower olefin or propylene. Therefore, the method for producing a lower olefin composition of the present invention is effective when producing a lower olefin such as propylene.

[0162] [Lower Olefin Composition] The lower olefin composition of the present invention is a composition containing lower olefins and / or derivatives thereof, which are cracking products of the hydrocarbon composition of the present invention.

[0163] The "lower olefin" refers to an unsaturated hydrocarbon having 2 to 4 carbon atoms and containing one or two unsaturated bonds in one molecule. Specific examples include ethylene, propylene, butene (1-butene, 2-butene, isobutene), and butadiene (1,2-butadiene and 1,3-butadiene). Among these, at least one selected from the group consisting of ethylene, propylene, 1-butene, and 2-butene is preferred.

[0164] The "derivative thereof", i.e., the "derivative of a lower olefin" may be a compound produced when the hydrocarbon composition of the present invention is cracked, or may be a compound obtained using a lower olefin that is a cracking product of the hydrocarbon composition of the present invention. The "derivative of a lower olefin" is not particularly limited, and examples thereof include the following ethylene derivatives, propylene derivatives, and butene derivatives.

[0165] a) Ethylene derivatives: Ethylene oxide, ethylene glycol, ethanolamine, glycol ether, etc., obtained by the oxidation reaction of ethylene Vinyl chloride monomer, 1,1,1-trichloroethane, vinylidene chloride, polyvinyl chloride, etc., obtained by the chlorination of ethylene α-olefins obtained by the polymerization of ethylene, and higher alcohols obtained by the oxo reaction and subsequent hydrogenation reaction using the α-olefins as raw materials Low-density to high-density polyethylene, etc., obtained by the polymerization of ethylene Vinyl acetate, etc., obtained by the reaction of ethylene with acetic acid Acetaldehyde, obtained by the Wacker reaction of ethylene, and its derivative, ethyl acetate, etc.

[0166] b) Propylene derivatives: Acrylonitrile obtained by ammoxidation of propylene, etc. Acrolein, acrylic acid and acrylic acid esters obtained by selective oxidation of propylene Normal butyraldehyde, 2-ethylhexanol and other oxo alcohols obtained by the oxo reaction of propylene Polypropylene obtained by polymerization of propylene Propylene oxide and propylene glycol obtained by selective oxidation of propylene, isopropyl alcohol obtained by hydration of propylene Acetone obtained by the Wacker reaction of propylene, methyl isobutyl ketone and acetone cyanohydrin obtained from acetone, and methyl methacrylate obtained from acetone cyanohydrin.

[0167] c) Butene derivatives: Butadiene obtained by oxidative dehydrogenation of butene. 1,4-butanediol obtained through acetoxylation, hydrogenation, and hydrolysis of butadiene, and pyrrolidones such as γ-butyl lactone and N-methylpyrrolidone obtained from this as a raw material. Tetrahydrofuran, polytetramethylene glycol, etc. obtained by dehydration of pyrrolidones. Various synthetic rubbers obtained using butadiene.

[0168] By using the hydrocarbon composition of the present invention, it is possible to produce a lower olefin composition which contains lower olefins and in which the production of methanol is suppressed, i.e., which has a low methanol content, for the reasons described above.

[0169] The content of the lower olefin in the lower olefin composition is not particularly limited, and is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and particularly preferably 98% by mass or more, relative to 100% by mass of the total mass of the lower olefin composition. The content of the lower olefin in the lower olefin composition may be 100% by mass.

[0170] The content of methanol in the lower olefin composition is not particularly limited, and is preferably 10,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, still more preferably 100 ppm by mass or less, particularly preferably 10 ppm by mass or less, particularly preferably 5 ppm by mass or less, and most preferably 1 ppm by mass or less, relative to the total mass of the lower olefin composition. The content of methanol in the lower olefin can be measured by gas chromatography.

[0171] Such a lower olefin composition can be obtained by cracking the hydrocarbon composition of the present invention.

[0172] [Polyolefin Polymer] The polyolefin polymer of the present invention is a polyolefin polymer obtained by polymerizing the lower olefin and / or its derivative contained in the lower olefin composition of the present invention by a known polymerization method. The polyolefin polymer of the present invention contains repeating units derived from an olefin (hereinafter referred to as "lower olefin units") or repeating units derived from a derivative thereof (hereinafter referred to as "lower olefin derivative units").

[0173] The polyolefin polymer of the present invention may be a polymer containing only lower olefin units, a polymer containing lower olefin units and lower olefin derivative units, or a polymer containing only lower olefin derivative units.

[0174] The "repeating unit" means a unit formed directly by the polymerization reaction of a lower olefin and / or a derivative thereof, and may be a unit in which a part of the unit is converted into a different structure by treating the polymer.

[0175] The polyolefin polymer of the present invention may be a polyolefin polymer obtained by polymerizing a lower olefin composition of the present invention from which methanol contained in the composition has been removed by a known methanol separation method such as distillation. Alternatively, the polyolefin polymer of the present invention may be a polyolefin polymer obtained by polymerizing the lower olefin composition of the present invention as is. In this case, since the methanol content in the lower olefin composition is low for the reasons described above, the performance of the catalyst used in polymerizing the lower olefin is not substantially impaired by methanol, and the obtained polyolefin polymer is excellent in quality from the viewpoints of molecular weight distribution, impurities, etc.

[0176] An example of the method for producing a polyolefin-based polymer of the present invention is a method for producing a polyolefin-based polymer, which includes obtaining a lower olefin composition by the above-mentioned method for producing a lower olefin composition of the present invention, and polymerizing the lower olefin contained in the lower olefin composition to obtain a polyolefin-based polymer.

[0177] [Method for determining a hydrocarbon composition] The method for determining a hydrocarbon composition of the present invention is a method for determining a hydrocarbon composition used in the production of lower olefins, wherein the hydrocarbon composition is a hydrocarbon composition containing decomposition products of chemically recycled raw materials such as waste plastics, and the method comprises determining that the hydrocarbon composition is acceptable as a hydrocarbon composition to be used in the production of lower olefins when a measured value of the content of oxygen-containing compounds in the hydrocarbon composition is equal to or less than a predetermined threshold, and subjecting the determined hydrocarbon composition to a thermal cracking treatment.

[0178] In the method for determining a hydrocarbon composition of the present invention, the "oxygen-containing compound" has the same meaning as the oxygen-containing compound in the hydrocarbon composition of the present invention, and the preferred range is also the same. ...chemically recycled raw material" has the same meaning as the "chemically recycled raw material" in the method for producing a hydrocarbon composition of the present invention described above, and the preferred range is also the same. In the method for determining a hydrocarbon composition of the present invention, the "decomposition product of waste plastics" has the same meaning as the "decomposition product of waste plastics" in the method for producing a hydrocarbon composition of the present invention, and the preferred range is also the same.

[0179] In the method for determining a hydrocarbon composition of the present invention, the "decomposition product of waste plastics" is more specifically synonymous with the "decomposition product of waste plastics" described in the section on the method for producing a hydrocarbon composition of the present invention, and is a hydrocarbon composition obtained by purifying a pyrolysis oil such as a plastic decomposition oil produced by the thermal decomposition of waste plastics.

[0180] In the method for determining a hydrocarbon composition of the present invention, the hydrocarbon composition to be determined can be a mixture containing a decomposition product of a chemically recycled feedstock such as waste plastics and another naphtha prepared in advance. In the method for determining a hydrocarbon composition of the present invention, the "other naphtha prepared in advance" is synonymous with the "other naphtha prepared in advance" in the hydrocarbon composition of the present invention. Furthermore, the "mixture" in the method for determining a hydrocarbon composition of the present invention is synonymous with the "mixture" in the hydrocarbon composition of the present invention.

[0181] More specifically, the method for determining a hydrocarbon composition of the present invention is a method for determining a hydrocarbon composition that, for the reasons described above, if the measured content of oxygen-containing compounds in the hydrocarbon composition, measured using elemental analysis, is 900 mass ppm or less in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, then the hydrocarbon composition is determined to be acceptable as a hydrocarbon composition to be used in the production of lower olefins, and the hydrocarbon composition is subjected to thermal cracking treatment.More specifically, the method for determining a hydrocarbon composition of the present invention is a method for determining a hydrocarbon composition that, for the reasons described above, if the measured content of oxygen-containing compounds in the hydrocarbon composition, measured using gas chromatography, is 260 mass ppm or less (preferably 160 mass ppm or less), relative to the total mass of the hydrocarbon composition, then the hydrocarbon composition is determined to be acceptable as a hydrocarbon composition to be used in the production of lower olefins, and the hydrocarbon composition is subjected to thermal cracking treatment. Furthermore, more specifically, the method for determining a hydrocarbon composition of the present invention comprises, for the reasons described above, determining that the hydrocarbon composition is acceptable as a hydrocarbon composition to be used for producing lower olefins when the measured content of oxygen-containing compounds in the hydrocarbon composition using elemental analysis is 900 mass ppm or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, and the measured content of oxygen-containing compounds in the hydrocarbon composition using gas chromatography is 260 mass ppm or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, and subjecting the hydrocarbon composition to a thermal cracking treatment.

[0182] In the present invention, the judgment is preferably carried out immediately before the hydrocarbon composition is charged into a naphtha cracker.

[0183] In the method for determining a hydrocarbon composition of the present invention, the oxygen-containing compound may specifically include at least one selected from the group consisting of alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds. Note that the alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds in the method for determining a hydrocarbon composition of the present invention are synonymous with the alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds in the hydrocarbon composition of the present invention, respectively.

[0184] The present invention will be explained in more detail below by way of experimental examples and comparative examples, which are given for the purpose of illustration only and are not intended to limit the present invention in any way.

[0185] The names of the compounds used in the experimental examples and comparative experimental examples are as follows: Dehydration catalyst X: silica-alumina catalyst (trade name: N633HN, manufactured by JGC Catalysts and Chemicals Co., Ltd.) Hydrogenation catalyst A: Ni / SiO ２ Catalyst B: Ru / Al (product name: N113, manufactured by JGC Catalysts and Chemicals Co., Ltd.) ２ O ３ Hydrogenation catalyst C: Ru / C catalyst (trade name: Ru / C, A type, dry base Ru content 5%, water content 56%, manufactured by N.E. Chemcat Corporation)

[0186] <Evaluation Method> (1) Measurement of Oxygen-Containing Compound Content by Elemental Analysis For the hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples, the content of oxygen-containing compounds, calculated as oxygen atoms, was measured using elemental analysis according to the following procedure. Oxygen analysis was performed on the hydrocarbon compositions using an elemental analyzer (device name: Vario EL cube, manufactured by Elemental) to calculate the oxygen atom content (unit: ppm by mass). This value was used as the oxygen atom-equivalent content (unit: ppm by mass) of oxygen-containing compounds contained in the hydrocarbon composition. The measurement conditions were: fractionation column = 1170°C, measurement mode = O (oxygen). Benzoic acid was used as the standard substance, and the analytical value was the average of three measured values. When the measured oxygen atom value was below the lower detection limit of this elemental analyzer, it was recorded as "ND (not detected)."

[0187] (2) Measurement of the Content of Oxygen-Containing Compounds (Alcohol Compounds, Ketone Compounds, Carboxylic Acid Compounds, Aldehyde Compounds, and Ether Compounds) by Gas Chromatography For the hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples, the contents of alcohol compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds in terms of oxygen atoms in the hydrocarbon compositions were measured using gas chromatography in accordance with any of the following measurement conditions 1 to 3. The measurement conditions used for measuring each of the above-mentioned compounds are shown in Table 1.

[0188] (Measurement Condition 1) The hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples were directly, without pretreatment, measured for gas chromatograms using gas chromatography (GC) employing the backflush method under the following GC measurement conditions. The content of each compound was calculated based on the peak area of ​​each compound in the obtained gas chromatogram and a three-point calibration curve prepared in advance. The content of each compound, converted into oxygen atoms, was calculated from the content (mg / L) of each compound and the molecular weight of that compound. Measurements were performed three times, and the average value was taken as the content of each compound. Furthermore, when the measured value was below the lower detection limit of the analytical instrument, it was recorded as "ND (not detected)." (GC measurement conditions) Measurement device: Gas chromatograph measurement device (device name: GC-2030, manufactured by Shimadzu Corporation) Detector: Hydrogen flame ionization detector (FID) Detector temperature: 275°C Column (1st): DB-1 (trade name, manufactured by Agilent Technologies, inner diameter 0.53 mm x length 30 m, film thickness 0.5 μm) Column (2nd): GS-oxyplot (trade name, manufactured by Agilent Technologies, inner diameter 0.53 mm x length 10 m, film thickness 10 μm) The column (1st) and column (2nd) were connected in series. In addition, a backflush method was adopted for the measurement. Column temperature: 50°C (retention time 5 minutes) → temperature increase at 10°C / minute → 240°C (retention time: 6 minutes) Carrier gas: Helium (pressure controlled) Injection port temperature: 225°C Injection volume: 3 μL (splitless)

[0189] (Measurement Condition 2) The hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples were directly subjected to gas chromatography mass spectrometry (GC / MS) without pretreatment, and the gas chromatogram, m / z, and fragment pattern of each compound were measured under the following GC / MS measurement conditions. The content of each compound was calculated based on the peak area of ​​the obtained gas chromatogram and a three-point calibration curve prepared in advance. The content of each compound in terms of oxygen atoms was calculated from the content (mg / L) of each compound and the molecular weight of that compound. Measurements were performed three times, and the average value was used as the content of each compound. Furthermore, when the measured value was below the lower detection limit of the analyzer, it was recorded as "ND (not detected)." (GC / MS measurement conditions) Measurement apparatus: Gas chromatograph mass spectrometer (apparatus name: 7890B / 5977B MSD, manufactured by Agilent Technologies) Detector: Hydrogen flame ionization detector (FID), mass spectrometer (MS) Detector temperature: 300°C Column: BPX-5 (trade name, manufactured by Shimadzu GLC Corporation, inner diameter 0.32 mm x length 60 m, film thickness 0.25 μm) Column temperature: 50°C (retention time 5 minutes) → heating at 10°C / minute → 300°C (retention time: 10 minutes) Carrier gas: Helium (flow rate: 4.1 ml / minute) Injection port temperature: 300°C Injection volume: 1 μL (split ratio: 1 / 30) MS ion source temperature: 230°C MS quadrupole temperature: 150°C MS transfer line temperature: 280°C Ionization method: Scan EI Measurement mode: SIM (m / z = 108) Measurement mass range: m / z = 20 to 600

[0190] (Measurement Condition 3) The hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples were directly subjected to gas chromatography mass spectrometry (GC / MS) without pretreatment, and the gas chromatogram, and the m / z and fragment pattern of each compound were measured under the following GC / MS measurement conditions. The content of each compound was calculated based on the peak area of ​​the obtained gas chromatogram and a three-point calibration curve prepared in advance. The content of each compound in terms of oxygen atoms was calculated from the content (mg / L) of each compound and the molecular weight of that compound. Measurements were performed three times, and the average value was used as the content of each compound. Furthermore, when the measured value was below the lower detection limit of the analyzer, it was recorded as "ND (not detected)." (GC / MS measurement conditions) Measurement device: Gas chromatograph mass spectrometer (device name: 7890B / 5977B MSD, manufactured by Agilent Technologies) Column: TC-FFAP (trade name, manufactured by GL Sciences, inner diameter 0.25 mm x length 60 m, film thickness 0.25 μm) Detector: Hydrogen flame ionization detector (FID), mass spectrometer (MS) Detector temperature: 240°C Carrier gas: Helium (flow rate: 1.2 ml / min) Column temperature: 50°C (retention time 5 min) → heating at 10°C / min → 230°C (retention time: 12) Injection port temperature: 240°C Injection volume: 1 μL (split ratio: 1 / 30) MS ion source temperature: 230°C MS quadrupole temperature: 150°C MS transfer line temperature: 280°C Ionization method: Scan EI Measurement mode: SIM (m / z = 60, 66, 73, 74, 87, 105, 108) Measurement mass range: m / z = 19 to 400

[0191] In Table 1, "3 (FID)" means that the measurement was performed using an FID as a detector, and for example, "3 (SIM60)" means that the measurement was performed using a mass spectrometer (MS) as a detector, with the measurement mode set to SIM and m / z = 60; that is, the subscript SIM means that the above "m / z value" was used.

[0192]

[0193] (3) Measurement of Olefin Compound Content by PONA Analysis Method For the hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples, gas chromatograms were measured using gas chromatography (GC) and PONA analysis under the following GC measurement conditions. The peak areas of the obtained gas chromatograms were used to calculate the olefin compound content in accordance with JIS K 2536-2 (Petroleum Products - Testing Methods for Components). (GC Measurement Conditions) Measuring apparatus: Gas chromatograph measuring apparatus (apparatus name: 8890GC, manufactured by Agilent Technologies) Detector: Hydrogen flame ionization detector (FID) Detector temperature: 250°C Column: HP-5 (trade name, manufactured by Agilent Technologies, inner diameter 0.320 mm × length 2 m, film thickness 0.25 μm) and HP-1 (Part Number: 19091S-004E) (trade name, manufactured by Agilent Technologies, inner diameter 0.250 mm × length 100 m, film thickness 0.50 μm) were used in series connection. Column temperature: 5.0°C (holding time 10 minutes) → heating at 5°C / min → 50°C (holding time: 43 minutes) → heating at 1.6°C / min → 100°C (holding time: 0 minutes) → heating at 1.0°C / min → 180°C (holding time: 0 minutes) Carrier gas: helium (constant pressure mode) Injection port temperature: 250°C Injection volume: 0.2 μL (split ratio: 130:1) Total component analysis software: SmartDHA2

[0194] Reference Example 1 Preparation of Model Hydrocarbon Composition A model hydrocarbon composition was prepared by blending petroleum-derived naphtha manufactured by our company as a hydrocarbon solvent with oxygen-containing compounds such as alcohol compounds, ketone compounds, aldehyde compounds, carboxylic acid compounds, and ether compounds shown in Table 1 so as to achieve the oxygen atom-equivalent contents shown in Table 2. Table 3 shows the analytical results of the oxygen atom-equivalent contents of oxygen-containing compounds measured using the above-mentioned measurement method and the olefin compound contents measured using the PONA analytical method for the model hydrocarbon composition.

[0195]

[0196] <Purification Treatment> [Example 1] 0.56 g of hydrogenation catalyst A, 0.56 g of dehydration catalyst X (mass ratio of hydrogenation catalyst / dehydration catalyst = 1.0), and 39 g of a model hydrocarbon composition were charged into a corrosion-resistant steel autoclave (internal volume 100 ml) used as a purification apparatus, and hydrogen was further injected into the autoclave to maintain a pressure of 6 MPaG, and the autoclave was sealed. Next, the temperature inside the autoclave was raised to 240°C while hydrogen was supplied to maintain the pressure inside the autoclave at 6 MPaG, and purification treatment was carried out for 2 hours. Thereafter, the temperature inside the autoclave was allowed to cool to room temperature (25°C), and the model hydrocarbon composition after purification treatment was removed from the autoclave. The analysis results of the plastic cracked oil obtained after purification treatment are shown in Table 3.

[0197] Comparative Example 1 A reaction was carried out under the same conditions as in Example 1, except that the dehydration catalyst X was not used. The analysis results of the plastic decomposition oil obtained after the refining treatment are shown in Table 3.

[0198]

[0199] In Example 1, a hydrogenation catalyst and a dehydration catalyst were used in combination during the purification treatment, and therefore the content of oxygen-containing compounds and the content of olefinic compounds measured using PONA analysis in the hydrocarbon composition after the purification treatment were reduced compared to Reference Example 1. In Comparative Example 1, a dehydration catalyst was not used during the purification treatment, and only a hydrogenation catalyst was used, so the content of oxygen-containing compounds and the content of olefinic compounds measured using PONA analysis in the hydrocarbon composition after the purification treatment were both reduced compared to Reference Example 1, but were higher than in Example 1.

[0200] Example 2 The same procedure as in Example 1 was carried out, except that the amount of dehydration catalyst X added was 0.28 g and the mass ratio of hydrogenation catalyst / dehydration catalyst was 2.0. A decrease in oxygen-containing compounds was observed in the obtained hydrocarbon composition.

[0201] Example 3 The same procedure as in Example 1 was carried out, except that the amount of dehydration catalyst X added was 0.93 g and the mass ratio of hydrogenation catalyst / dehydration catalyst was 0.6. A decrease in oxygen-containing compounds was observed in the obtained hydrocarbon composition.

[0202] Example 4 The procedure of Example 1 was repeated except that the hydrogenation catalyst A was replaced with an equivalent amount of the hydrogenation catalyst B. A decrease in the amount of oxygen-containing compounds was observed in the resulting hydrocarbon composition.

[0203] Example 5 The procedure of Example 1 was repeated except that the hydrogenation catalyst A was replaced with an equivalent amount of the hydrogenation catalyst C. A decrease in the amount of oxygen-containing compounds was observed in the resulting hydrocarbon composition.

[0204] Example 6 The same procedure as in Example 1 was carried out, except that the amount of the model hydrocarbon composition added was changed to 19.5 g. A decrease in the amount of oxygen-containing compounds was observed in the obtained hydrocarbon composition.

[0205] Comparative Example 2 The procedure of Example 1 was repeated except that the hydrogenation catalyst A was not used. The resulting hydrocarbon composition had a higher content of oxygen-containing compounds than that of Example 1.

[0206] Comparative Example 3 The procedure was the same as in Example 4, except that the dehydration catalyst X was not used. The resulting hydrocarbon composition had a higher content of oxygen-containing compounds than in Example 4.

[0207] Comparative Example 4 The procedure was the same as in Example 5, except that the dehydration catalyst X was not used. The resulting hydrocarbon composition had a higher content of oxygen-containing compounds than in Example 5.

Claims

1. A method for producing a hydrocarbon composition, comprising purifying a pyrolysis oil produced by the thermal decomposition of a chemically recycled feedstock to obtain a hydrocarbon composition, wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound, and the pyrolysis oil contains an oxygen-containing compound, and the purification process comprises subjecting the oxygen-containing compound in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst).

2. A method for producing the hydrocarbon composition according to claim 1, comprising reducing the amount of oxygen-containing compounds in the pyrolysis oil by the hydrogenation and dehydration reactions.

3. A method for producing the hydrocarbon composition according to claim 1, comprising converting at least a portion of the oxygen-containing compounds in the pyrolysis oil into paraffins by the hydrogenation and dehydration reactions.

4. A method for producing a hydrocarbon composition according to claim 1, comprising subjecting the chemically recycled raw material to thermal decomposition without a catalyst to obtain a thermal decomposition product.

5. The method for producing a hydrocarbon composition according to claim 1, wherein the purification step comprises carrying out the hydrogenation reaction or the dehydration reaction so that the content of oxygen-containing compounds in the resulting hydrocarbon composition, as measured by elemental analysis, is 900 mass ppm or less in terms of oxygen atoms.

6. The method for producing a hydrocarbon composition according to claim 1, wherein the hydrogenation reaction and / or the dehydration reaction is carried out in the refining process so that the content of olefinic compounds in the resulting hydrocarbon composition, as measured using the PONA analysis method, is 180 mass ppm or less.

7. The method for producing a hydrocarbon composition according to claim 1, wherein the mass ratio of the hydrogenation catalyst to the dehydration catalyst used in the refining treatment is 0.5 or more and 90 or less.

8. A method for producing a hydrocarbon composition according to claim 1, wherein the total mass of the dehydration catalyst and hydrogenation catalyst used in the refining treatment is 300 mass% or more and 2000 mass% or less relative to the oxygen atom equivalent amount of oxygen-containing compounds in the pyrolysis oil.

9. The method for producing a hydrocarbon composition according to claim 1, wherein the hydrogenation catalyst and the dehydration catalyst are present in an independent state in the refining treatment.

10. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled raw material comprises waste plastic.

11. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled feedstock comprises biomass.

12. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled raw material contains a polyolefin polymer in an amount of 60 mass % or more based on the total mass of the chemically recycled raw material.

13. A method for producing a hydrocarbon composition according to claim 1, comprising carrying out the hydrogenation reaction or the dehydration reaction in the purification treatment so that the content of oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 260 mass ppm or less in terms of oxygen atoms.

14. The method for producing a hydrocarbon composition according to claim 1, wherein the oxygen-containing compound comprises at least one compound selected from the group consisting of alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds.

15. A method for producing a hydrocarbon composition according to claim 14, wherein the content of alcohol compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 40 mass ppm or less in terms of oxygen atoms.

16. A method for producing a hydrocarbon composition according to claim 14, wherein the content of ketone compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 70 mass ppm or less in terms of oxygen atoms.

17. A method for producing a hydrocarbon composition according to claim 14, wherein the content of carboxylic acid compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured by gas chromatography, is 30 mass ppm or less in terms of oxygen atoms.

18. A method for producing a hydrocarbon composition as described in claim 14, wherein the content of aldehyde compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured using gas chromatography, is 15 mass ppm or less in terms of oxygen atoms.

19. A method for producing a hydrocarbon composition as described in claim 14, wherein the content of ether compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured using gas chromatography, is 5 mass ppm or less in terms of oxygen atoms.

20. The method for producing a hydrocarbon composition according to claim 1, wherein the hydrogenation catalyst contains at least one metal selected from transition metals belonging to Groups 8 to 10 of the periodic table.

21. The method for producing a hydrocarbon composition according to claim 1, wherein the dehydration catalyst comprises at least one selected from the group consisting of silica, alumina, silica-alumina, and zeolite.

22. A hydrocarbon composition containing decomposition products of a chemically recycled raw material, wherein the content of oxygen-containing compounds measured by elemental analysis is 900 mass ppm or less in terms of oxygen atoms, and the chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound.

23. A method for producing a lower olefin composition, comprising: obtaining a hydrocarbon composition by purifying a pyrolysis oil produced by thermal decomposition of a chemically recycled feedstock, wherein the chemically recycled feedstock contains a polyolefin polymer and an oxygen-containing compound; in the purification process, the oxygen-containing compound in the pyrolysis oil is subjected to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst), thereby obtaining the hydrocarbon composition; and feeding the hydrocarbon composition into a naphtha cracker and thermally decomposing it to obtain the lower olefin composition.

24. A method for producing a polyolefin polymer, comprising: obtaining a lower olefin composition by the method for producing a lower olefin composition according to claim 23; and polymerizing the lower olefin contained in the lower olefin composition to obtain a polyolefin polymer.

25. A method for determining a hydrocarbon composition to be used in the production of lower olefins, wherein the hydrocarbon composition is a hydrocarbon composition containing decomposition products of a chemically recycled raw material, and when a measured value of the content of oxygen-containing compounds in the hydrocarbon composition is equal to or less than a predetermined threshold, the method comprises determining that the hydrocarbon composition is acceptable as a hydrocarbon composition to be used in the production of lower olefins, and subjecting the hydrocarbon composition to a thermal cracking treatment.

26. The method for determining a hydrocarbon composition according to claim 25, wherein the chemically recycled raw material comprises a polyolefin polymer and an oxygen-containing compound.

27. A method for determining a hydrocarbon composition according to claim 25, wherein the hydrocarbon composition is a hydrocarbon composition obtained by purifying a pyrolysis oil produced by pyrolysis of a chemically recycled feedstock.

28. A method for determining a hydrocarbon composition according to claim 27, wherein the refining treatment comprises subjecting oxygen-containing compounds in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in a hydrogen atmosphere in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst).

29. The method for determining a hydrocarbon composition according to claim 25, wherein the hydrocarbon composition is a mixture containing a cracking product of a chemical recycling feedstock and another naphtha that has been prepared in advance.

30. A method for determining a hydrocarbon composition according to claim 25, comprising determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured using elemental analysis, is 900 mass ppm or less in terms of oxygen atoms.

31. A method for determining a hydrocarbon composition according to claim 25, comprising determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the content of olefinic compounds in the hydrocarbon composition, as measured using the PONA analytical method, is 180 mass ppm or less.

32. A method for determining a hydrocarbon composition according to claim 25, comprising determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the content of the oxygen-containing compounds in the hydrocarbon composition, measured using gas chromatography, is 260 mass ppm or less in terms of oxygen atoms.

33. The method for determining a hydrocarbon composition according to claim 25, wherein the chemically recycled material comprises waste plastic.

34. The method for determining a hydrocarbon composition according to claim 25, wherein the chemically recycled feedstock comprises biomass.

35. A method for determining a hydrocarbon composition according to claim 25, wherein the chemically recycled raw material contains polyolefin polymers in an amount of 60 mass% or more based on the total mass of the chemically recycled raw material.

36. The method for determining a hydrocarbon composition according to claim 25, wherein the determination is made immediately before the hydrocarbon composition is charged into a naphtha cracker.

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