WO2025178122A1 - Hydrocarbon composition, production method therefor, method for producing lower-olefin composition, method for producing polyolefin-based polymer, and method for assessing hydrocarbon composition - Google Patents

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

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 above-mentioned lower olefin composition.
Furthermore, the present invention relates to a method for determining a hydrocarbon composition.

Plastics are widely used in a variety of products, including beverage containers, food packaging, household goods, and automobile parts. However, in order to reduce environmental impact and resource waste, reprocessing waste plastic and converting it into new products and materials as recycled plastic has become an important issue from the perspectives of environmental protection and sustainability. For this reason, in recent years, methods have been considered in which plastic decomposition oil is obtained from waste plastic using known thermal decomposition methods such as thermal recycling and chemical recycling, and the resulting decomposition oil is then further distilled to obtain purified decomposition oil.

Meanwhile, a typical method for producing lower olefins is to thermally crack (steam crack) naphtha (a crude oil-derived hydrocarbon mixture with a boiling point range of approximately 30-230°C) obtained by refining crude oil in the presence of steam using a naphtha cracker facility. Furthermore, in recent years, there has been research into producing lower olefins using plastic cracking oil obtained from waste plastic as a raw material.

According to studies by the present inventors, it has been found that pyrolysis oils such as plastic cracking oil 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, and this can poison the catalyst in the downstream hydrogenation tank, and when the oxygen-containing compound is an organic acid, can cause corrosion of the equipment, and that methanol derived from the pyrolysis product of the oxygen-containing compounds is produced in the obtained lower olefin product.
Methanol derived from the thermal decomposition products of oxygen-containing compounds, when mixed with lower olefin products such as propylene, may deteriorate the performance of catalysts used in polymerizing the lower olefins to produce olefin polymers such as polypropylene.

As a technique for refining plastic decomposition oil produced by thermal decomposition of waste plastics, for example, Patent Document 1 discloses a method of subjecting waste plastic decomposition oil to hydrorefining treatment as is.
Furthermore, Patent Documents 2 and 3 disclose a method for reducing catalyst coking by diluting waste plastic cracking oil with diesel and hydrorefining the diluted oil.
Furthermore, Patent Document 4 discloses a method for producing high-quality jet fuel using a hydrogenation catalyst and an isomerization catalyst in a hydrorefining step.
Furthermore, 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.

Japanese Patent Application Publication No. 09-048983 Japanese Patent Application Laid-Open No. 2007-77324 Japanese Patent Application Laid-Open No. 2005-105027 Japanese Patent Application Laid-Open No. 2020-90660

Hydrogen Energy Systems Vol. 33, No. 2 (2008)

However, the methods described in Patent Documents 1 to 4 were unable to sufficiently reduce the oxygen-containing compounds in the plastic decomposition 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 decomposition 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 plastic cracking oil.

The present invention aims to solve these problems.
That is, 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 determining 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, and a polyolefin polymer obtained by polymerizing the lower olefin composition.

As a result of extensive investigations aimed at solving the above-mentioned problems, the inventors discovered that when the pyrolysis oil produced by the thermal decomposition of waste plastics is purified, the content of oxygen-containing compounds can be significantly reduced by subjecting it to hydrogenation and dehydration reactions in the presence of two types of catalysts that exist independently, thereby solving the above-mentioned problems and completing the present invention.
[1] A method for producing a hydrocarbon composition, comprising purifying a pyrolysis oil produced by pyrolysis of a chemical recycling raw material to obtain a hydrocarbon composition,
the chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound,
the pyrolysis oil contains oxygenates,
The method for producing a hydrocarbon composition includes subjecting oxygen-containing compounds in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) under a hydrogen atmosphere in the refining treatment.
[2] The method for producing the hydrocarbon composition according to [1], comprising reducing the amount of oxygen-containing compounds in the pyrolysis oil by the hydrogenation reaction and the dehydration reaction.
[3] The 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], 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 any one of [1] to [4], wherein the hydrogenation reaction or the dehydration reaction is carried out in the purification treatment 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 any one of [1] to [5], wherein the hydrogenation reaction and/or the dehydration reaction is carried out in the purification process so that the content of olefinic compounds in the obtained hydrocarbon composition, as measured by a PONA analysis method, 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] The method for producing a hydrocarbon composition according to any one of [1] to [7], wherein the total mass of the dehydration catalyst and the 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 the oxygen-containing compounds in the pyrolysis oil.
[9] The method for producing a hydrocarbon composition according to any one of [1] to [8], 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 any one of [1] to [9], wherein the chemically recycled raw material includes waste plastic.
[11] The method for producing a hydrocarbon composition according to any one of [1] to [10], wherein the chemically recycled raw material includes biomass.
[12] The method for producing a hydrocarbon composition according to any one of [1] to [11], wherein the chemically recycled raw material contains a polyolefin polymer in an amount of 60 mass% or more relative to the total mass of the chemically recycled raw material.
[13] The method for producing a hydrocarbon composition according to any one of [1] to [12], 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 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 is 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.
[15] The method for producing a hydrocarbon composition according to [14], 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.
[16] The method for producing a hydrocarbon composition according to [14] or [15], 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.
[17] The method for producing a hydrocarbon composition according to any one of [14] to [16], 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.
[18] The method for producing a hydrocarbon composition according to any one of [14] to [17], 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.
[19] The method for producing a hydrocarbon composition according to any one of [14] to [18], 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.
[20] The 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 containing a decomposition product of a chemically recycled raw material,
the content of oxygen-containing compounds measured by elemental analysis is 900 ppm by mass or less in terms of oxygen atoms,
The chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound.
Hydrocarbon composition.
[23] A method for producing a hydrocarbon composition by purifying a pyrolysis oil produced by pyrolysis of a chemical recycling raw material,
The chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound,
The refining treatment includes subjecting oxygen-containing compounds in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) under a hydrogen atmosphere to obtain the hydrocarbon composition,
a method for producing a lower olefin composition, comprising: feeding the hydrocarbon composition into a naphtha cracker and thermally cracking the hydrocarbon composition to obtain a lower olefin composition.
[24] Obtaining a lower olefin composition by the method for producing a lower olefin composition according to [23],
A method for producing a polyolefin polymer, comprising polymerizing a lower olefin contained in the lower olefin composition to obtain a polyolefin polymer.
[25] A method for determining a hydrocarbon composition used in the production of lower olefins, comprising:
The hydrocarbon composition is a hydrocarbon composition containing a decomposition product of a chemical recycling raw material,
A method for determining a hydrocarbon composition, comprising: determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the 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.
[26] The method for determining a hydrocarbon composition according to [25], wherein the chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound.
[27] The hydrocarbon composition determination method according to [25] or [26], wherein the hydrocarbon composition is a hydrocarbon composition obtained by purifying a pyrolysis oil produced by pyrolysis of a chemical recycling feedstock.
[28] The method for determining a hydrocarbon composition according to [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 hydrocarbon composition is a mixture containing a decomposition product of a chemical recycling feedstock and another naphtha prepared in advance. [29] The hydrocarbon composition determination method according to any one of [25] to [28].
[30] The method for determining a hydrocarbon composition according to any one of [25] to [29], 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.
[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 producing 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 any one of [25] to [32], wherein the chemically recycled raw material includes waste plastic.
[34] The method for determining a hydrocarbon composition according to any one of [25] to [33], wherein the chemically recycled raw material includes biomass.
[35] The method for determining a hydrocarbon composition according to any one of [25] to [34], wherein the chemically recycled raw material contains a polyolefin polymer in an amount of 60 mass% or more relative to the total mass of the chemically recycled raw material.
[36] The method for determining a hydrocarbon composition according to any one of [25] to [35], wherein the determination is performed immediately before the hydrocarbon composition is charged into a naphtha cracker.

[X1] A hydrocarbon composition containing a decomposition product of waste plastic,
A hydrocarbon composition having an oxygen-containing compound content of 900 mass ppm or less in terms of oxygen atoms, as measured by elemental analysis.

[X2] A hydrocarbon composition according to [X1], in which the content of oxygen-containing compounds, as measured using gas chromatography, is 160 mass ppm or less in terms of oxygen atoms.

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

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

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

[X6] A hydrocarbon composition according to any one of [X1] to [X5], in which the content of carboxylic acid compounds as the oxygen-containing compounds, as measured using gas chromatography, is 30 mass ppm or less in terms of oxygen atoms.

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

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

[X9] A hydrocarbon composition according to any one of [X1] to [X8], wherein the hydrocarbon composition is a mixture containing decomposition products of waste plastics and other naphtha that has been prepared in advance.

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

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

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

[X13] A method for producing a hydrocarbon composition, comprising purifying a cracked oil (i.e., a pyrolysis oil, preferably a plastic cracked oil) produced by the thermal decomposition of waste plastics to obtain a hydrocarbon composition,
The method for producing a hydrocarbon composition includes subjecting oxygen-containing compounds in the cracked oil (i.e., thermal cracking oil, preferably plastic cracking oil) to a hydrogenation reaction and a dehydration reaction in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) under a hydrogen atmosphere in the refining treatment.

[X14] A method for producing a hydrocarbon composition according to [X13], wherein the hydrogenation catalyst and the dehydration catalyst exist independently in the refining process.

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

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

[X17] A 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 process is 0.5 (preferably 10 or more) to 90 or less.

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

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

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

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

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

[X23] A method for producing a hydrocarbon composition according to any one of [X13] to [X22], 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.

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

[X25] A 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.

[X26] A 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.

[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 for use in the production of lower olefins when the measured content of oxygen-containing compounds in the hydrocarbon composition is equal to or less than a predetermined threshold, and subjecting the hydrocarbon composition to a thermal cracking treatment.

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

[X29] A method for determining a hydrocarbon composition according to [X27] or [X28], wherein the hydrocarbon composition is a mixture containing decomposition products of waste plastics and other naphtha that has been prepared in advance.

[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 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.

[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 the production of 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.

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

The method for producing a hydrocarbon composition of the present invention makes it possible to efficiently produce a hydrocarbon composition with a reduced content of oxygen-containing compounds by refining pyrolysis oil, such as plastic cracking oil, obtained by thermally cracking chemically recycled raw materials such as waste plastics.

The hydrocarbon composition provided by the present invention has a low content of oxygen-containing compounds. This prevents a significant increase in the amount of carbon monoxide (CO) produced by the decomposition of oxygen-containing compounds in a cracker facility when the hydrocarbon composition is thermally cracked to produce various lower olefins, which can poison the catalyst in the downstream hydrogenation tank. Furthermore, if the oxygen-containing compounds contain organic acids, this can prevent corrosion of the equipment.

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 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, a decrease in the performance of the polymerization catalyst can be suppressed.

The hydrocarbon composition evaluation method of the present invention makes it possible to accurately determine whether a hydrocarbon composition containing decomposition products of waste plastics is suitable as a hydrocarbon composition for use in the production of lower olefins.

The present invention is described in detail below. The present invention is not limited to the following description, and can be modified and implemented as desired without departing from the spirit of the present invention.

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 A or more and B or less.
In this specification, "mass %" indicates the content ratio of a specified component contained in a total amount of 100 mass %, and "mass %" indicates the content ratio of a specified component contained in a total amount of 100 mass %.
"% by mass" and "% by weight" have the same meaning.
"Optional" or "optionally" means that the subsequently described circumstance may or may not occur, and thus the description includes both the occurrence and non-occurrence of the circumstance.
All steps described herein can be performed in any suitable order unless otherwise stated herein or clearly contradicted by context.

In this specification, "chemically recycled raw materials" refers to waste plastics and biomass.
In this specification, "waste plastic" refers to used plastic products and plastic materials (hereinafter referred to as "used plastic products, etc."), specifically materials that have been used once and can be reused, recycled, or disposed of after being discarded, 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., specific examples of which include wood and agricultural residues, paper, food waste, compost, livestock excrement, and organic matter obtained from microorganisms, and refers to materials that produce pyrolysis oil through chemical recycling.

In this specification, the term "thermal decomposition" in "thermal decomposition of waste plastics" is not particularly limited as long as it is a method that can decompose waste plastics to obtain plastic decomposition oil (sometimes simply referred to as "cracked oil" or "thermal decomposition oil"). For example, conventional thermal decomposition processes, known decomposition processes using supercritical fluids or subcritical fluids such as known hydrothermal decomposition processes, and known catalytic pyrolysis processes can be used.
The "conventional pyrolysis treatment" refers to a thermochemical decomposition treatment of organic substances under conditions that are substantially oxygen-free and without the supply of oxygen from the outside, under the influence of temperature alone. More specifically, a person skilled in the art can appropriately optimize the pyrolysis reaction temperature in a pyrolysis reactor, the residence time in the pyrolysis reactor, the type of the pyrolysis reactor, the pressure in the pyrolysis reactor, the type of pyrolysis catalyst, and the like to perform the pyrolysis treatment.
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 in a state that is neither liquid nor gas. When water is used as the fluid, thermal decomposition occurs in the presence of water (hydrothermal decomposition). When water is used, specifically, the temperature and pressure are controlled to heat the material to 100 to 700°C, more preferably 150 to 500°C, and the hydrothermal decomposition treatment is performed by utilizing the high reactivity of supercritical water or subcritical water.
The term "catalytic pyrolysis" refers to the thermochemical decomposition 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. 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 ceolite.

In the present invention, "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).

In the present invention, "naphtha" refers to a liquid hydrocarbon derived from a fossil fuel such as coal, crude oil (petroleum), or natural gas, or derived from biomass, and refers to a composition 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 contained in the hydrocarbon composition can be measured using a known analytical method such as gas chromatography.

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."

[Hydrocarbon Composition]
The hydrocarbon composition of the present invention is a hydrocarbon composition containing decomposition products of a chemically recycled feedstock, in which 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 is a hydrocarbon composition containing a polyolefin polymer and an oxygen-containing compound.
If the content of the oxygen-containing compound is 900 ppm by mass or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition, when the hydrocarbon composition is thermally cracked to produce various lower olefins, a significant increase in the amount of carbon monoxide (CO) produced by decomposition of the oxygen-containing compound in a cracker facility, which would otherwise poison the catalyst in a downstream hydrogenation tank, can be suppressed. Furthermore, if the oxygen-containing compound contains an organic acid, corrosion of the equipment can be suppressed.
In addition, when the content of the oxygen-containing compound is 900 mass ppm or less in terms of oxygen atoms relative to the total mass of the hydrocarbon composition, the amount of methanol produced during thermal decomposition is small, and therefore a lower olefin composition having a low methanol content can be produced with a high olefin yield.

Furthermore, it is preferable that the hydrocarbon composition of the present invention has an oxygen-containing compound content of 260 mass ppm or less, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition, as measured using gas chromatography, since this more reliably suppresses the aforementioned catalyst poisoning and equipment corrosion, reduces the amount of methanol produced during thermal cracking, and enables the production of a lower olefin composition with a low methanol content at a higher olefin yield.

Details about the oxygen-containing compound used in the present invention will be provided later.

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% or more by mass of the hydrocarbon composition.

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 composition may contain only one or two or more of these hydrocarbons having 7 or more carbon atoms.
In the hydrocarbon composition of the present invention, the content of these hydrocarbons having 7 or more carbon atoms is 14.0% by mass or more, relative to 100% by total mass of the hydrocarbon composition. When the content of hydrocarbons having 7 or more carbon atoms is 14.0% by mass or more, lower olefins can be efficiently obtained when the hydrocarbon composition is thermally cracked in a naphtha cracker, and 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 light 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 light olefins of the present invention is preferably 42.0 mass% or less, more preferably 38.0 mass% or less, and even more preferably 35.0 mass% or less.
The above upper and lower limits can be combined in any combination. 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.

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 - Testing methods for components), 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, the required performance is sufficiently satisfied even if the content is, for example, 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.
The above upper and lower limits can be combined in any way.
The details of the olefin-based compound will be described later.

A hydrocarbon composition having an olefinic compound content of 180 mass ppm or less, as measured using the PONA analytical method, can be obtained by the hydrocarbon composition production method of the present invention described below. In particular, this can be obtained by carrying out a hydrogenation reaction and/or a dehydration reaction in the refining process in the hydrocarbon composition production method of the present invention.

Details of the analysis method using the PONA analysis method mentioned above will be provided later.

The hydrocarbon composition of the present invention is suitable as a cracker feedstock for use in waste plastic recycling plants, where waste plastics are recycled to produce lower olefins, particularly propylene.

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.

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

"Decomposition products of waste plastics" refers to decomposition oils obtained by reusing or recycling waste plastics, such as plastic decomposition oils produced from substances obtained by decomposing the above-mentioned waste plastics, and plastic decomposition refined oils obtained by refining such plastic decomposition oils.Specific examples include hydrocarbon compositions obtained by the method for producing a hydrocarbon composition of the present invention described below.
"Other naphtha prepared in advance" refers to naphtha derived from fossil fuels such as coal, crude oil (petroleum), and natural gas, or naphtha derived from biomass, excluding "decomposition products of waste plastics."
"Fossil fuel" refers to at least one selected from petroleum, coal, and natural gas.
"Bio-based naphtha" is 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 methane and sugar ethanol obtained from firewood, charcoal, dried livestock manure, etc., but are not limited to these.

[Chemical recycled materials]
The chemically recycled raw material in the present invention is a raw material used to produce the hydrocarbon composition of the present invention, and the hydrocarbon composition of the present invention contains a decomposition product obtained by thermally decomposing the chemically recycled raw material.
Furthermore, the hydrocarbon composition of the present invention can also be obtained by purifying decomposition products such as plastic decomposition oils that are 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.

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, just like 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, mitigating the burden on the environment.
It goes without saying that the waste plastic may be a plastic derived from biomass or may contain a compound derived from biomass.

The chemically recycled raw material in the present invention can contain, as waste plastic, a polyolefin polymer, which will be described later.
The lower limit of the content of the polyolefin polymer in the chemically recycled raw material in the present invention is not particularly limited, and can usually be set to 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% by total mass of the chemically recycled raw material.
On the other hand, the upper limit of the content of the polyolefin-based polymer is not particularly limited, and from the viewpoint of economic efficiency such as the production cost required to highly purify the chemically recycled raw material, it can usually be set to 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% by total mass of the chemically recycled raw material.
The 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, still 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.

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 usually 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% by 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 usually 200,000 mass ppm or less, preferably 100,000 mass ppm or less, more preferably 50,000 mass ppm or less, even more preferably 20,000 mass ppm or less, and particularly preferably 10,000 mass ppm or less, relative to 100% of the total mass of the chemically recycled raw material.
The upper and lower limits can be combined arbitrarily. That is, the content ratio of the oxygen-containing compound contained in the chemically recycled raw material in the present invention is not particularly limited, and can be 200 ppm by mass or more and 200,000 ppm by mass or less, preferably 500 ppm by mass or more and 100,000 ppm by mass or less, more preferably 1,000 ppm by mass or more and 50,000 ppm by mass or less, still more preferably 2,000 ppm by mass or more and 20,000 ppm by mass or less, and particularly preferably 5,000 ppm by mass or more and 10,000 ppm by mass or less, relative to 100% by total mass of the chemically recycled raw material.

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

[Olefin compounds]
The pyrolysis oil of the present invention or the hydrocarbon composition of the present invention may contain an olefinic compound.
The olefin-based compound in the present invention is an unsaturated hydrocarbon having 5 to 12 carbon atoms and containing one or two unsaturated bonds per molecule, and specific examples thereof 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 olefin-based compound in the present invention is not particularly limited, and examples thereof include compounds that are produced by the thermal decomposition of the polyolefin-based polymer in the present invention through a hydrogen elimination reaction.

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

The oxygen-containing compound used 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 include at least one compound 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).

The upper limit of the content of oxygen-containing compounds contained in the hydrocarbon composition of the present invention, as measured using elemental analysis, is 900 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 pyrolyzing the hydrocarbon composition obtained by pyrolyzing waste plastics and refining the resulting plastic cracked oil, and of suppressing the amount of methanol produced in the resulting lower olefin composition.

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 standpoint 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, even more preferably 5.0 ppm by mass or more, even more preferably 10.0 ppm by mass or more, even 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.

The above upper and lower limits can be combined in any manner. That is, the content of oxygen-containing compounds in the hydrocarbon composition of the present invention as measured using elemental analysis is not particularly limited, and may be substantially free of oxygen-containing compounds (0 ppm by mass), or may be 0.1 ppm by mass to 900 ppm by mass, relative to the total mass of the hydrocarbon composition. 0.2 ppm by mass to 800 ppm by mass is preferred, 1.0 ppm by mass to 700 ppm by mass is more preferred, 5.0 ppm by mass to 600 ppm by mass is even more preferred, 10.0 ppm by mass to 500 ppm by mass is even more preferred, 200 ppm by mass to 400 ppm by mass is even more preferred, and 250 ppm by mass to 300 ppm by mass is particularly preferred.

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

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 set to 260 ppm by mass or less, in terms of oxygen atoms, relative to the total mass of the hydrocarbon composition, 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, and even optionally 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, 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 refining the resulting plastic cracked oil, and of suppressing the amount of methanol produced in the resulting lower olefin composition.

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 it is acceptable for the composition to contain substantially no oxygen-containing compounds (0 ppm by mass). However, from the standpoint 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.

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

In the present invention, the method for controlling the content ratio of oxygen-containing compounds in a hydrocarbon composition, as measured using elemental analysis or gas chromatography, is not particularly limited, and examples include the manufacturing method for 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 with different oxygen-containing compound content ratios, and a method of diluting the hydrocarbon composition by blending it with diesel or the like.

(alcohol-based compounds)
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. Specific examples 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.

The upper limit of the content of alcohol-based compounds contained in the hydrocarbon composition of the present invention is not particularly limited, but from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further pyrolyzing a hydrocarbon composition obtained by pyrolyzing waste plastics and refining 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 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, even more preferably 20 ppm by mass or less, and even more preferably 10 ppm by mass or less.

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 it is acceptable for the composition to contain substantially no alcohol-based compounds (0 ppm by mass). Alternatively, from the standpoint 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 typically 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.

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

(Ketone compounds)
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.

The upper limit of the content of ketone compounds contained in the hydrocarbon composition of the present invention is not particularly limited. From the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further pyrolyzing a hydrocarbon composition obtained by pyrolyzing waste plastics and refining 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 70 ppm by mass or less, more preferably 40 ppm by mass or less, even more preferably 20 ppm by mass or less, even more preferably 18 ppm by mass or less, even more preferably 15 ppm by mass or less, even more preferably 12 ppm by mass or less, and particularly preferably 10 ppm by mass or less.

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 it is acceptable for the composition to contain substantially no ketone compounds (0 ppm by mass). Alternatively, from the standpoint 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 typically 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.

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

(carboxylic acid compounds)
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.

The upper limit of the content of carboxylic acid compounds contained in the hydrocarbon composition of the present invention is not particularly limited. From the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further pyrolyzing a hydrocarbon composition obtained by pyrolyzing waste plastics and refining 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, even 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.

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 it is acceptable for the hydrocarbon composition to contain substantially no carboxylic acid compounds (0 ppm by mass). Alternatively, from the standpoint 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 typically 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.

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

(aldehyde compounds)
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.

The upper limit of the content of aldehyde compounds contained in the hydrocarbon composition of the present invention is not particularly limited. From the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further pyrolyzing a hydrocarbon composition obtained by pyrolyzing waste plastics and refining 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 25 ppm by mass or less, even more preferably 20 ppm by mass or less, even more preferably 15 ppm by mass or less, even more preferably 10 ppm by mass or less, even more preferably 5 ppm by mass or less, and particularly preferably 2.5 ppm by mass or less.

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 it is acceptable for the composition to contain substantially no aldehyde compounds (0 ppm by mass). Alternatively, from the standpoint 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 typically be 0.1 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition. 0.2 ppm by mass or more is preferred, 0.4 ppm by mass or more is more preferred, 0.5 ppm by mass or more is even more preferred, 0.8 ppm by mass or more is even more preferred, 1.0 ppm by mass or more is even more preferred, 1.6 ppm by mass or more is even more preferred, and 2.0 ppm by mass or more is particularly preferred.

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

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

For example, asymmetric ethers having an asymmetric structure with respect to the ether oxygen atom include 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.

On the other hand, examples of ethers having a symmetric structure with respect to the ether oxygen atom (hereinafter referred to as "symmetric ethers") include 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 ), and dipropyl ether (CH ₃ -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -CH ₃ ).

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

The upper limit of the content of ether compounds contained in the hydrocarbon composition of the present invention is not particularly limited, but from the viewpoints of suppressing catalyst poisoning and equipment corrosion when a lower olefin composition is produced by further pyrolyzing a hydrocarbon composition obtained by pyrolyzing waste plastics and refining 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 45 ppm by mass or less, more preferably 35 ppm by mass or less, even more preferably 25 ppm by mass or less, even 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.

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 is acceptable for the composition to contain substantially no ether compounds (0 ppm by mass). Alternatively, from the standpoint 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 typically be 0.1 ppm by mass or more, calculated as oxygen atoms, relative to the total mass of the hydrocarbon composition. 0.2 ppm by mass or more is preferred, 0.4 ppm by mass or more is more preferred, 0.5 ppm by mass or more is even more preferred, 0.6 ppm by mass or more is even more preferred, and 0.8 ppm by mass or more is even more preferred. 1.0 ppm by mass or more is even more preferred, and 2.0 ppm by mass or more is particularly preferred.

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

The upper limit of the total content of the alcohol compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds contained in the hydrocarbon composition of the present invention is not particularly limited. 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 refining 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, 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, even more preferably 150 ppm by mass or less, even more preferably 120 ppm by mass or less, even 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.

On the other hand, the lower limit of the total content of the alcohol compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds contained in the hydrocarbon composition of the present invention is not particularly limited, and may be substantially absent (0 ppm by mass). Alternatively, from the standpoint 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, is typically 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, even more preferably 2.0 ppm by mass or more, even more preferably 3.0 ppm by mass or more, and particularly preferably 5.0 ppm by mass or more.

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

[Method of producing hydrocarbon composition]
The process for producing the hydrocarbon composition of the present invention will be described below.
The method for producing a hydrocarbon composition of the present invention comprises purifying a pyrolysis oil, such as a plastic cracking oil, produced by the thermal decomposition of a chemically recycled feedstock such as waste plastics, to obtain a hydrocarbon composition, wherein the chemically recycled feedstock comprises 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).

For the reasons described above, in the method for producing a hydrocarbon composition of the present invention, it is preferable that the hydrogenation reaction or the dehydration reaction is carried out 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.
Furthermore, in the method for producing a hydrocarbon composition of the present invention, for the reasons described above, 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 by gas chromatography, is 260 ppm by mass or less, preferably 160 ppm by mass or less, calculated as oxygen atoms.
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.

In the method for producing a hydrocarbon composition of the present invention, the oxygen-containing compound can specifically include 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.
In the method for producing a hydrocarbon composition of the present invention, the alcohol-based compound, the ketone-based compound, the carboxylic acid-based compound, the aldehyde-based compound, and the ether-based compound are respectively synonymous with the alcohol-based compound, the ketone-based compound, the carboxylic acid-based compound, the aldehyde-based compound, and the ether-based compound in the hydrocarbon composition of the present invention.

[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, 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.

In the present invention, the pyrolysis oil is preferably plastic decomposition oil. Plastic decomposition oil is decomposition oil produced by the thermal decomposition of waste plastic, and is usually decomposition oil made from discarded plastic.
The plastic cracked oil in the present invention may be a distillate of a naphtha-equivalent fraction obtained by distilling and refining cracked oil produced by thermal cracking of waste plastics.
In the present invention, the method for thermally decomposing waste plastics is not particularly limited, and known methods such as those described in Japanese Patent Application Laid-Open Nos. 9-235563 and 10-088149 can be used.

The waste plastic raw material (hereinafter referred to as "waste plastic raw material") applicable to the method for producing a hydrocarbon composition of the present invention is not particularly limited, and examples include known thermoplastic resins, known thermosetting resins, and known synthetic rubbers.

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 copolymers of olefin monomers with small proportions of other monomers, 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.

Examples of thermosetting resins include phenolic resin, melamine resin, urea resin, alkyd resin, and polyurethane (PU).

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 their cross-linked products (vulcanizates).

These waste plastic raw materials may be one type alone or a mixture of two or more types.

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-based resin compositions containing two or more polyolefin-based polymers as the main component.

The biomass feedstock applicable to the method for producing a hydrocarbon composition of the present invention is not particularly limited, and is a compound derived from known non-edible biomass and/or a compound derived from known non-fossil fuel.
The use of biomass raw materials 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.

In the present invention, a compound derived from a fossil fuel refers to at least one compound selected from petroleum-derived compounds, coal-derived compounds, and natural gas-derived compounds.

The plastic cracked oil is required to have specific distillation properties, and the 95% distillation temperature is preferably 100 to 600°C, particularly preferably above 300°C, and even more preferably above 400°C, and the initial boiling point is preferably 200°C or lower, particularly preferably 100°C or lower.
Furthermore, with regard to 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 150 to 250°C, and the initial boiling point is preferably 200°C or lower, particularly 100°C or lower.

The pyrolysis oil in 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 compounds in the pyrolysis oil before reduction by the hydrogenation reaction and the dehydration reaction) 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 further 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 compound is usually 30,000 mass ppm or less, or even 10,000 mass ppm or less, in terms of oxygen atoms, relative to 100% by total mass of the pyrolysis oil.
It may be 7000 mass ppm or less, 6000 mass ppm or less, or 5000 mass ppm or less.
The upper and lower limits can be arbitrarily combined. That is, the content ratio of the oxygen-containing compound contained in the pyrolysis oil in the present invention is not particularly limited, and is, for example, 1500 mass ppm or more and 30000 mass ppm or less in terms of oxygen atoms relative to 100% of the total mass of the pyrolysis oil.
It may be 2000 mass ppm or more and 10000 mass ppm or less, 3000 mass ppm or more and 7000 mass ppm or less, 3500 mass ppm or more and 6000 mass ppm or less, or 4000 mass ppm or more and 5000 mass ppm or less.

[Refining process]
The method for producing a hydrocarbon composition of the present invention comprises purifying the above-mentioned pyrolysis oil to obtain a hydrocarbon composition.
In the refining process, 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 and a dehydration catalyst, which will be described later, to obtain a hydrocarbon composition. The 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.

In the refining treatment, 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 in the thermal cracking oil such as the plastic cracking oil.
The phrase "existing in an independent state" means that the hydrogenation catalyst and the dehydration catalyst are present in a reaction system in a physically separable state. Specifically, the phrase "existing in an independent state" excludes a state in which the dehydration catalyst is supported on a carrier having hydrogenation catalytic activity, and a state in which the hydrogenation catalyst is supported on a carrier having dehydration catalytic activity.

In the present invention, it is preferable that at least a portion of the oxygen-containing compounds in the pyrolysis oil is converted into paraffins by the hydrogenation and dehydration reactions. Paraffins are converted from, for example, alcohol compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds.
Furthermore, as will be described later, in the refining treatment, oxygen-containing compounds contained in thermal cracking oils such as plastic cracking oils are converted by a hydrogenation reaction into corresponding alcohol-based compounds, which are then converted by a dehydration reaction into corresponding unsaturated hydrocarbon compounds, which are then converted by a hydrogenation reaction into corresponding saturated hydrocarbon compounds. In the production method of the present invention, the hydrogenation catalyst and the dehydration catalyst are present in a mixed state, which allows the hydrogenation reaction and the dehydration reaction to proceed in concert, thereby efficiently reducing the oxygen-containing compounds in the obtained 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.

In the present invention, it is preferable to carry out the hydrogenation reaction and/or the dehydration reaction in the refining process so that the content of olefinic compounds in the obtained hydrocarbon composition, as measured using the PONA analytical method, is 180 mass ppm or less. This configuration tends to more effectively reduce the amount of coking produced during thermal cracking of the hydrocarbon composition. The preferred range of the content of olefinic compounds in the hydrocarbon composition, as measured using the PONA analytical method, is the same as the preferred range of the content of olefinic compounds in the hydrocarbon composition of the present invention described above.

A specific embodiment of the phrase "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 present in a physically separable state.
Alternatively, another specific embodiment of "existing in an independent state" refers to a case where the layer containing the hydrogenation catalyst and the layer containing the dehydration catalyst are arranged in series in the reaction system. More specifically, examples include an embodiment in which the layer containing the hydrogenation catalyst and the layer containing the dehydration catalyst are arranged in that order in one reactor, and an embodiment in which the reactor containing the hydrogenation catalyst and the reactor containing the dehydration catalyst are arranged in that order, directly or indirectly connected to each other.

<Hydrogenation catalyst>
In the method for producing a hydrocarbon composition of the present invention, the hydrogenation catalyst is a catalyst used in a 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) and (2):
(1) Oxygen-containing compounds contained in the thermal cracking oil such as the plastic cracking oil are subjected to a hydrogenation reaction to convert them into corresponding alcohol compounds.
(2) The unsaturated hydrocarbon compounds produced in the dehydration reaction described below are hydrogenated to convert them into the corresponding saturated hydrocarbon compounds.

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.

As the hydrogenation catalyst in the present invention, a known hydrogenation catalyst containing at least one metal selected from transition metals belonging to Groups 8 to 10 of the periodic table is preferred, from the viewpoint of enabling efficient hydrogenation of oxygen-containing compounds in the thermal cracking oil such as the plastic cracking oil.
Ruthenium is an example of a transition metal belonging to Group 8 of the periodic table.
An example of a transition metal belonging to Group 9 of the periodic table is 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.

More specifically, examples of the hydrogenation catalyst 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 hydrogenation catalysts can be used alone or in combination of two or more.

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

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

<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.

(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 convert them into the corresponding unsaturated hydrocarbon compounds.

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.

Specific examples of the dehydration catalyst include known dehydration catalysts such as silica, alumina, silica-alumina, and zeolite, which are solid acids, and molybdenum oxide and tungsten oxide, which are transition metal oxide catalysts. 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, and silica-alumina and zeolite are more preferred.
In order to avoid isomerization reactions, the acidity of the dehydration catalyst may be adjusted by adding an alkaline component to the catalyst.
The above dehydration catalysts can be used alone or in combination of two or more.

The form of the dehydration catalyst is not particularly limited, but a solid catalyst or complex catalyst is preferred, with a solid catalyst being preferred as it allows for the production of higher quality hydrocarbon compositions.

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

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." The hydrogenation catalyst and the dehydration catalyst may be present in a mixed state in the reaction system, and the hydrogenation reaction and the dehydration reaction (hereinafter referred to as "hydrogenation-dehydration reaction") may be carried out.
) preferably proceeds in the same reaction apparatus (reactor).

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

<Conditions for hydrogenation and dehydration reactions>
The hydrogen pressure during the hydrogenation reaction and dehydration reaction is not particularly limited, and is usually 1 to 10 MPa, and 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 reaction and dehydration reaction of the oxygen-containing compound decreases. On the other hand, as the hydrogen pressure increases, the hydrogenation reaction generates excessive heat, making it difficult to control the hydrogenation reaction and increasing the equipment costs for heat removal.

The reaction temperature is not particularly limited, and is usually 150 to 450° C., and more preferably 200 to 350° C. By setting the reaction temperature to 200° C. or higher, the hydrogenation reaction and dehydration reaction tend to proceed more effectively, and by setting the reaction temperature to 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 a temperature defined as the catalyst weight average temperature.
The liquid hourly space velocity (LHSV) is not particularly limited, and is usually preferably 0.1 to 10 ^h , more preferably 0.5 to 5.0 ^h , and even more preferably 0.5 to 2.0 ^h . If the liquid hourly space velocity is lower than 0.5 ^h , excessive cracking of hydrocarbons may occur, and if it is higher than 2.0 ^h , the hydrogenation reaction and dehydration reaction may not proceed sufficiently.
Furthermore, the hydrogen/pyrolysis oil ratio (preferably the hydrogen/plastic cracking oil ratio) is not particularly limited, but is usually preferably 20 to 1000 Nm ³ -H ₂ /kL-pyrolysis oil, and more preferably 200 to 500 Nm ³ /kL. By setting the hydrogen/pyrolysis oil ratio to 200 to 500 Nm ³ /kL, the hydrogen necessary for the reaction can be supplied and catalyst deterioration can be suppressed. The hydrogen/pyrolysis oil ratio is based on the pumped volume of pyrolysis oil (kL: kiloliters).

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 oxygen-containing 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 combined in any desired manner. For example, the mass ratio of the hydrogenation catalyst to the dehydration catalyst is preferably 0.5 to 90, more preferably 0.6 to 30, even more preferably 0.7 to 10, and particularly preferably 0.8 to 3.0.

The lower limit of the total mass of the dehydration catalyst and hydrogenation catalyst used in the purification treatment is not particularly limited, and 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, and 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, and even more preferably 1500 mass% or less, based on the oxygen atom equivalent of the oxygen-containing compounds in the pyrolysis oil.
For example, the total mass of the dehydration catalyst and the hydrogenation catalyst is preferably 300% by mass or more, more preferably 300% by mass or more and 2000% by mass or less, and even more preferably 600% by mass or more and 1500% by mass or less, based on the oxygen atom equivalent of the oxygen-containing compounds in the pyrolysis oil.

In the method for producing a hydrocarbon composition of the present invention, the hydrocarbon composition obtained by refining thermal cracking oil such as plastic cracking oil is then subjected to a process identical 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. Ethylene and propylene, in particular, are relatively inexpensive and have excellent properties that make them suitable as feedstocks for a wide range of products.

[Method for producing lower olefin composition]
The method for producing the 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").

More specifically, the method for producing a lower olefin composition of the present invention includes 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 the purification process includes subjecting the 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) to obtain the hydrocarbon composition, and the method includes introducing the hydrocarbon composition into a naphtha cracker for thermal decomposition to obtain the lower olefin composition.

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."

By thermally cracking the hydrocarbon composition of the present invention, a lower olefin composition containing lower olefins and methanol is produced.
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, it is possible to significantly reduce the amount of methanol produced and also to suppress catalyst poisoning in the hydrogenation tank and corrosion of the equipment.

The method for producing the lower olefin composition of the present invention can be carried out in accordance with a conventional method, except that the hydrocarbon composition of the present invention is used.
That is, the hydrocarbon composition of the present invention (hereinafter may be 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.

Among the conditions for thermal decomposition, the ratio of the hydrocarbon composition to the water vapor is preferably 20 to 100 parts by mass of water vapor per 100 parts by mass of the hydrocarbon composition, more preferably 30 to 70 parts by mass, and particularly preferably 35 to 60 parts by mass. 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 used for 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.

The reaction temperature for thermal cracking is usually 700 to 1000°C, preferably 750 to 950°C. If the reaction temperature is below 700°C, the thermal cracking of the hydrocarbon composition will not proceed sufficiently, resulting in a lower yield of the desired lower olefins. If the reaction temperature exceeds 1000°C, the thermal cracking of the hydrocarbon composition will be excessive, resulting in increased generation of undesirable by-products such as methane, and a lower yield of the desired lower olefins.

The thermal cracking reaction time 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 will not proceed sufficiently, and the yield of the desired lower olefins will tend to decrease. If the reaction time exceeds 1 second, the thermal cracking of the hydrocarbon composition will be excessive, increasing the generation of undesirable by-products such as methane and tending to decrease the yield of the desired lower olefins.

The reaction pressure for pyrolysis 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).

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

The reaction product containing the lower olefin thus obtained can be subjected to treatments such as purification and fractionation according to conventional methods, thereby obtaining lower olefins such as ethylene, propylene, butene, and butadiene, aromatic hydrocarbons, and other hydrocarbons, respectively.
Saturated hydrocarbons such as ethane and propane can be recovered and subjected to thermal cracking again.
Among 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 butene and butane mixture remaining after extraction is preferably utilized or fractionated by polymerization, rectification, or the like in a separate process.

As mentioned above, methanol has a detrimental effect on polymerization catalysts used in the polymerization of 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. This makes it effective for producing lower olefins such as propylene.

The method for producing a lower olefin composition using the hydrocarbon composition of the present invention makes it possible to produce a lower olefin composition that contains lower olefins and in which methanol production is suppressed, i.e., a lower olefin composition with a low methanol content.

By using the method for producing a lower olefin composition of the present invention, a propylene composition containing propylene and methanol can be produced.
More specifically, by using the method for producing a lower olefin composition of the present invention, it is possible to produce a propylene composition which contains propylene and in which the production of methanol is suppressed, i.e., a propylene composition with a low methanol content.

As mentioned above, methanol adversely affects polymerization catalysts used in polymerizing lower olefins or propylene. Therefore, the method for producing a lower olefin composition of the present invention is effective when producing lower olefins such as propylene.

[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.

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

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.

a) Derivatives of ethylene:
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.

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

c) Derivatives of butene:
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 and polytetramethylene glycol obtained by dehydration of pyrrolidones. Various synthetic rubbers obtained using butadiene.

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

The content of lower olefins 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 especially preferably 98% by mass or more, relative to 100% by total mass of the lower olefin composition. The content of lower olefins in the lower olefin composition may be 100% by mass.

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, even 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 olefins can be measured by gas chromatography.

Such lower olefin compositions can be obtained by cracking the hydrocarbon composition of the present invention.

[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").

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.

The term "repeating unit" refers to a unit formed directly by the polymerization reaction of a lower olefin and/or its derivative, and may be a unit in which some of the units have been converted into a different structure by processing the polymer.

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 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 it 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.

One 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.

[Method for determining hydrocarbon composition]
The method for determining a hydrocarbon composition of the present invention is 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 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 value, and subjecting the determined hydrocarbon composition to a thermal cracking treatment.

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.
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.
In the method for determining a hydrocarbon composition of the present invention, the "chemically recycled raw material" has the same meaning as the "chemically recycled raw material" in the above-mentioned method for producing a hydrocarbon composition of the present invention, 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.

In the hydrocarbon composition determination method of the present invention, "decomposition products of waste plastics" is more specifically synonymous with the "decomposition products of waste plastics" described in the section on the hydrocarbon composition production method of the present invention, and is a hydrocarbon composition obtained by purifying pyrolysis oil, such as plastic decomposition oil, produced by the thermal decomposition of waste plastics.

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 raw material such as waste plastics and another naphtha that has been prepared in advance.
The "other naphtha prepared in advance" in the method for determining a hydrocarbon composition of the present invention has the same meaning as the "other naphtha prepared in advance" in the hydrocarbon composition of the present invention.
Furthermore, the term "mixture" in the method for determining a hydrocarbon composition of the present invention has the same meaning as the term "mixture" in the hydrocarbon composition of the present invention.

More specifically, the method for determining a hydrocarbon composition of the present invention is a method for determining a hydrocarbon composition, which 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 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, and subjecting the hydrocarbon composition to a thermal cracking treatment.
Furthermore, more specifically, the method for determining a hydrocarbon composition of the present invention is a method for determining a hydrocarbon composition, which 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 content of oxygen-containing compounds in the 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 relative to the total mass of the hydrocarbon composition, and subjecting the hydrocarbon composition to a 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.

In the present invention, the determination is preferably made immediately before the hydrocarbon composition is charged into the naphtha cracker.

In the method for determining a hydrocarbon composition of the present invention, the oxygen-containing compound can specifically include 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.
In the method for determining a hydrocarbon composition of the present invention, the alcohol-based compounds, ketone-based compounds, carboxylic acid-based compounds, aldehyde-based compounds, and ether-based compounds 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.

The present invention will be explained in more detail below by providing experimental examples and comparative experimental examples in place of the working examples. These are for illustrative purposes only and are not intended to limit the present invention in any way.

The names of the compounds used in the experimental examples and comparative experimental examples are as follows:
Dehydration catalyst X: silica-alumina catalyst (product name: N633HN, manufactured by JGC Catalysts and Chemicals Co., Ltd.)
Hydrogenation catalyst A: Ni/ _SiO2 -based catalyst (product name: N113, manufactured by JGC Catalysts and Chemicals Co., Ltd.)
Hydrogenation catalyst B: Ru/Al ₂ O ₃ catalyst (product name: HYAc-5E S-Type, manufactured by N.E. Chemcat Corporation)
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)

<Evaluation method>
(1) Measurement of Oxygen-Containing Compound Content by Elemental Analysis The hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples were measured for the oxygen-containing compound content in terms of oxygen atoms by elemental analysis according to the following procedure.
The hydrocarbon composition was subjected to oxygen analysis using an elemental analyzer (device name: Vario EL cube, manufactured by Elemental GmbH) to calculate the oxygen atom content (unit: mass ppm). This value was used as the oxygen atom-equivalent content (unit: mass ppm) of the oxygen-containing compound contained in the hydrocarbon composition.
The measurement conditions were as follows: fractionating column temperature = 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.
Furthermore, when the measured value of oxygen atoms is equal to or below the lower detection limit of this elemental analyzer, it is recorded as "ND (not detected)."

(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.

(Measurement Condition 1)
The hydrocarbon compositions obtained in the experimental examples and comparative experimental examples were directly, without pretreatment, subjected to gas chromatography (GC) employing a backflush method, and gas chromatograms were measured 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 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. In addition, 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 chromatogram measurement device (device name: GC-2030, manufactured by Shimadzu Corporation)
Detector: 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 × length 10 m, film thickness 10 μm)
The first and second columns were connected in series, and the backflush method was used for the measurements.
Column temperature: 50°C (holding time: 5 minutes) → heating at 10°C/minute → 240°C (holding time: 6 minutes)
Carrier gas: Helium (pressure controlled)
Inlet temperature: 225℃
Injection volume: 3 μL (splitless)

(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 any pretreatment, and gas chromatograms, and m/z and fragment patterns of each compound were measured under the GC/MS measurement conditions described below.
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 converted to 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. In addition, when the measured value was below the lower detection limit of the analytical instrument, 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)
Detector: 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 (holding time: 5 minutes) → heating at 10°C/minute → 300°C (holding time: 10 minutes)
Carrier gas: Helium (flow rate: 4.1 ml/min)
Inlet temperature: 300℃
Injection volume: 1 μL (split ratio: 1/30)
MS ion source temperature: 230°C
MS quadrupole temperature: 150℃
MS transfer line temperature: 280°C
Ionization method: Scan EI
Measurement mode: SIM (m / z = 108)
Measurement mass range: m/z = 20 to 600

(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 any pretreatment, and gas chromatograms, and m/z and fragment patterns of each compound were measured under the GC/MS measurement conditions described below.
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 converted to 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. In addition, when the measured value was below the lower detection limit of the analytical instrument, 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 (product name, manufactured by GL Sciences Inc., inner diameter 0.25 mm × length 60 m, film thickness 0.25 μm)
Detector: Flame ionization detector (FID), mass spectrometer (MS)
Detector temperature: 240°C
Carrier gas: Helium (flow rate: 1.2 ml/min)
Column temperature: 50°C (holding time 5 minutes) → heating at 10°C/minute → 230°C (holding time: 12 minutes)
Inlet temperature: 240℃
Injection volume: 1 μL (split ratio: 1/30)
MS ion source temperature: 230°C
MS quadrupole temperature: 150℃
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

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

(3) Measurement of Olefin Compound Content by PONA Analysis Method Gas chromatograms of the hydrocarbon compositions obtained in the Experimental Examples and Comparative Experimental Examples were measured using gas chromatography (GC) and PONA analysis method under the following GC measurement conditions.
The peak areas of the obtained gas chromatogram were used to calculate the content of olefinic compounds in accordance with JIS K 2536-2 (petroleum products - component testing method).
(GC measurement conditions)
Measurement device: Gas chromatogram measurement device (device name: 8890GC, manufactured by Agilent Technologies)
Detector: Flame ionization detector (FID)
Detector temperature: 250°C
Columns: 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 connected in series and used.
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)
Inlet temperature: 250℃
Injection volume: 0.2 μL (split ratio: 130:1)
Total component analysis software: SmartDHA2

[Reference example 1]
<Preparation of Model Hydrocarbon Compositions>
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-based compounds, ketone-based compounds, aldehyde-based compounds, carboxylic acid-based compounds, and ether-based compounds listed in Table 1 so as to obtain the oxygen atom-equivalent contents listed in Table 2.
The analytical results of the content of oxygen-containing compounds in terms of oxygen atoms measured using the above-mentioned measurement method and the content of olefinic compounds measured using the PONA analysis method for the model hydrocarbon composition are shown in Table 3.

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

[Comparative Example 1]
The 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 cracked oil obtained after the refining treatment are shown in Table 3.

In Example 1, a hydrogenation catalyst and a dehydration catalyst were used in combination during the purification treatment, and as a result, the content of oxygen-containing compounds and the content of olefinic compounds measured using the PONA analysis method 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. Therefore, in the hydrocarbon composition after the purification treatment, the content of oxygen-containing compounds and the content of olefinic compounds measured using the PONA analysis method were both reduced compared to Reference Example 1, but were higher than Example 1.

[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 resulting hydrocarbon composition.

[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 resulting hydrocarbon composition.

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

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

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

[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.

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

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

Claims (36)

A method for producing a hydrocarbon composition, comprising purifying a pyrolysis oil produced by pyrolysis of a chemical recycling feedstock to obtain a hydrocarbon composition,
the chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound,
the pyrolysis oil contains oxygenates,
The method for producing a hydrocarbon composition includes subjecting oxygen-containing compounds in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) under a hydrogen atmosphere in the refining treatment. The method for producing the hydrocarbon composition described in claim 1, comprising reducing the amount of oxygen-containing compounds in the pyrolysis oil by the hydrogenation reaction and dehydration reaction. The method for producing the hydrocarbon composition described in claim 1, comprising converting at least a portion of the oxygen-containing compounds in the pyrolysis oil into paraffins through the hydrogenation reaction and dehydration reaction. The method for producing the hydrocarbon composition described in claim 1, comprising obtaining a pyrolysis product from the chemically recycled raw material by thermal decomposition without a catalyst. The method for producing a hydrocarbon composition according to claim 1, wherein the refining 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 using elemental analysis, is 900 mass ppm or less in terms of oxygen atoms. 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 ppm by mass or less. 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 process is 0.5 or more and 90 or less. The 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% by mass or more and 2000% by mass or less, based on the oxygen atom equivalent amount of oxygen-containing compounds in the pyrolysis oil. 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 during the refining process. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled raw material includes waste plastic. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled raw material includes biomass. The method for producing a hydrocarbon composition according to claim 1, wherein the chemically recycled raw material contains 60 mass% or more of polyolefin polymer based on the total mass of the chemically recycled raw material. The method for producing a hydrocarbon composition according to claim 1, further comprising carrying out the hydrogenation reaction or the dehydration reaction in the refining process so that the content of oxygen-containing compounds in the resulting hydrocarbon composition, as measured using gas chromatography, is 260 mass ppm or less in terms of oxygen atoms. 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 compounds, ketone compounds, carboxylic acid compounds, aldehyde compounds, and ether compounds. The 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 using gas chromatography, is 40 mass ppm or less in terms of oxygen atoms. The 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 using gas chromatography, is 70 mass ppm or less in terms of oxygen atoms. The 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 using gas chromatography, is 30 mass ppm or less in terms of oxygen atoms. The method for producing a hydrocarbon composition according to 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. The method for producing a hydrocarbon composition according to claim 14, wherein the content of ether compounds as oxygen-containing compounds in the obtained hydrocarbon composition, as measured using gas chromatography, is 5 ppm by mass or less in terms of oxygen atoms. 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. 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. A hydrocarbon composition comprising decomposition products of a chemically recycled feedstock,
the content of oxygen-containing compounds measured by elemental analysis is 900 ppm by mass or less in terms of oxygen atoms,
The chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound.
Hydrocarbon composition. The method includes purifying a pyrolysis oil produced by pyrolysis of a chemical recycling raw material to obtain a hydrocarbon composition,
The chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound,
The refining treatment includes subjecting oxygen-containing compounds in the pyrolysis oil to a hydrogenation reaction and a dehydration reaction in the presence of a hydrogenation catalyst and a dehydration catalyst (excluding the hydrogenation catalyst) under a hydrogen atmosphere to obtain the hydrocarbon composition,
a method for producing a lower olefin composition, comprising: feeding the hydrocarbon composition into a naphtha cracker and thermally cracking the hydrocarbon composition to obtain a lower olefin composition. Obtaining a lower olefin composition by the method for producing a lower olefin composition according to claim 23;
A method for producing a polyolefin polymer, comprising polymerizing a lower olefin contained in the lower olefin composition to obtain a polyolefin polymer. 1. A method for determining a hydrocarbon composition used in the production of lower olefins, comprising:
The hydrocarbon composition is a hydrocarbon composition containing a decomposition product of a chemical recycling raw material,
A method for determining a hydrocarbon composition, comprising: determining that the hydrocarbon composition is acceptable for use in the production of lower olefins when the 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. The method for determining a hydrocarbon composition according to claim 25, wherein the chemically recycled raw material contains a polyolefin polymer and an oxygen-containing compound. The method for determining a hydrocarbon composition according to claim 25, wherein the hydrocarbon composition is a hydrocarbon composition obtained by purifying pyrolysis oil produced by thermal decomposition of a chemically recycled feedstock. The method for determining a hydrocarbon composition according to claim 27, wherein the refining process includes 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). The method for determining a hydrocarbon composition according to claim 25, wherein the hydrocarbon composition is a mixture containing decomposition products of chemically recycled feedstock and other naphtha that has been prepared in advance. The 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. The 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 ppm by mass or less. The 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. The method for determining a hydrocarbon composition described in claim 25, wherein the chemically recycled raw material includes waste plastic. The method for determining a hydrocarbon composition described in claim 25, wherein the chemically recycled material includes biomass. The 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. The method for determining a hydrocarbon composition described in claim 25, wherein the determination is made immediately before the hydrocarbon composition is charged into a naphtha cracker.