Production method of styrene monomer

Abstract

The present invention relates to a process for the co-production of propylene oxide and styrene monomers, which introduces a hydrocarbon liquid stream produced by the pyrolysis of waste plastics without compromising the overall performance of the process as well as the characteristics and quality of the different streams and end products thus obtained. The process can reduce de novo synthesis of styrene monomers and provide a polystyrene waste disposal approach different from incineration and / or dumping.

Description

[0001] This application claims the benefit of European patent application EP22382419.4 filed on April 29, 2022.

[0002] The present invention relates to a method for introducing products derived from waste plastic raw materials into a propylene oxide styrene monomer co-production process. Background Art

[0003] The process for co-production of propylene oxide (PO) and styrene monomer (SM), also known as the "PO / SM" process, includes oxidation of ethylbenzene (EB) to produce ethylbenzene hydroperoxide (EBHP), followed by catalytic reaction of EBHP with propylene to produce PO and 1-phenylethanol (MBA, also known as α-methylbenzyl alcohol), purification of PO, dehydration of MBA to produce SM; and hydrogenation of methyl phenyl ketone (MPK), a by-product of the first two reactions, to obtain MBA, which is then converted into SM.

[0004] The PO / SM process requires strict control of the flow specifications of different fluids and the working conditions at each stage of the process. The presence of different contaminants in different stages of the PO / SM process may cause several problems, such as contamination of the styrene monomer product by different azeotropes (such as xylene); the presence of light molecules such as alkanes, olefins, and cycloalkanes can lead to impure PO products; the presence of unsaturated molecules in the EB-containing stream may lead to the formation of polymers, thereby contaminating and clogging the process; the presence of acids in the circulating EB can lead to deterioration of oxidation selectivity.

[0005] The recycling of waste plastics has always been a hot topic in the field of environmental science and technology.

[0006] It is well known that waste plastics can produce high yields of light gas olefins (i.e., ethylene, propylene, butenes) and aromatics (i.e., benzene, toluene, xylenes (BTX), ethylbenzene (EB)) through pyrolysis, as well as low yields of paraffins, isoparaffins, and cycloparaffins. Pyrolysis can be configured to maximize propylene and / or aromatics, obtaining high yields of BTX and EB.

[0007] Processes for recovering polystyrene by pyrolysis of styrene-containing plastic wastes have been disclosed in the art. A major disadvantage is that, although the yield of styrene may be high, a large amount of by-products are also formed, resulting in SM products that do not meet international market specifications (e.g. ASTM D-2827). Therefore, polystyrene can be regenerated from the liquid fraction of polystyrene pyrolysis oil, but its properties are inferior compared to polystyrene prepared from pure styrene (pure styrene).

[0008] The challenge of purification of styrene monomer (SM) contained in pyrolysis oil is the presence of molecules with similar relative volatility to SM (o-xylene, p-xylene, m-xylene, etc.), which cannot be reduced to the required specification level by conventional distillation, as well as molecules with similar relative volatility (EB, isopropylbenzene, n-propylbenzene, etc.), which require very many separation steps by distillation and / or large amounts of energy. In addition, there are molecules containing heteroatoms (S, N, O, halogens) and products that cause coloration.

[0009] Therefore, there is a need to continuously develop methods for producing styrene monomer using feedstocks other than crude oil (e.g., feedstocks made from waste plastics) without compromising the overall process. Summary of the invention

[0010] The present inventors have surprisingly found that hydrocarbon liquid streams containing polystyrene produced by pyrolysis of waste plastics (such as waste plastic pyrolysis oil) are suitable for adding to a propylene oxide (PO) and styrene monomer (SM) co-production process without compromising the overall performance of the process and the characteristics and quality of the different streams and final products obtained therefrom.

[0011] As disclosed in the prior art, the oil obtained by pyrolysis of waste plastics is a complex mixture of various compounds, which may be incompatible with different stages of the PO / SM process. The hydrocarbon liquid stream produced by pyrolysis of waste plastics contains components that are considered as impurities in the final product and components that affect the chemical reactions occurring in the PO / SM process, making the product theoretically incompatible with the PO / SM process.

[0012] However, contrary to the knowledge of the prior art, as demonstrated in the experimental section, the present invention discloses that a hydrocarbon liquid stream obtained from polystyrene waste plastics rich in styrene monomer (also referred to herein as pyrolysis oil) can be incorporated into a PO / SM process for use without compromising the overall performance of the process or the quality and properties of the final product obtained. The process can reduce the de novo synthesis of styrene monomer and provides a different treatment option from incineration and / or dumping of polystyrene waste.

[0013] Furthermore, the hydrocarbon liquid stream obtained from polystyrene-based waste plastics can be used in existing PO / SM co-production process equipment without modification, as it is compatible with commonly used equipment and will not foul or damage the equipment.

[0014] Thus, the use of hydrocarbon liquid streams obtained from the pyrolysis of polystyrene waste plastics rich in styrene monomer is advantageous because it allows the use of oil to efficiently prepare recycled styrene monomer without the need to perform expensive and cumbersome fractionation and / or purification steps. In addition, the use of hydrocarbon liquid streams obtained from the pyrolysis of polystyrene waste plastics rich in styrene monomer allows the recovery of styrene monomer and ethylbenzene in the pyrolysis oil, which can increase the overall yield compared to a purification process that only recovers styrene monomer.

[0015] The present invention discloses a method for producing high-value products such as styrene monomer by processing waste plastics. The process may include the conversion of waste plastics, which may be cracked or pyrolyzed by low-temperature or high-temperature pyrolysis, thermal pyrolysis or catalytic pyrolysis, wherein the resulting hydrocarbon liquid product may be incorporated into a PO / SM process under specific conditions.

[0016] Therefore, a first aspect of the present invention relates to a method comprising:

[0017] a) providing a hydrocarbon liquid stream (10) produced by pyrolysis of waste plastics;

[0018] b) introducing the hydrocarbon liquid stream (10) into

[0019] b.1) A first fractionation unit (T1) to separate a C7 stream top stream (40), a first fractionation side stream (30), a heavy fraction stream from the bottom (20) and optionally a product side stream (50) containing α-methylstyrene (see Figure 1A );

[0020] or

[0021] b.2) a first fractionation unit (T1) to separate the C7 stream overhead (40) and the stream introduced into the second fractionation unit (T1') to obtain the first fractionation stream (30), the heavy fraction-containing stream from the bottom (20) and optionally a product side stream (50) containing alpha-methylstyrene (see Figure 1B );

[0022] or

[0023] b.3) a distillation column (D5) to obtain a distilled product stream (220) (see Figure 1C );

[0024] c) Conduct

[0025] c.1) feeding the first fractionated side stream (30) obtained in b.1) or b.2) or the distilled product stream (220) obtained in b.3) to a hydrotreating unit (HP) comprising a heterogeneous hydrotreating catalyst in the presence of hydrogen to obtain a product stream (80, 270) containing ethylbenzene;

[0026] or

[0027] c.2) feeding the first fractionated side stream (30) obtained in b.1) or b.2) to a distillation column (D5) to obtain a distilled product stream (220); then feeding the distilled product stream (220) to a hydroprocessing unit (HP) containing a heterogeneous hydroprocessing catalyst in the presence of hydrogen to obtain a product stream (270) containing ethylbenzene;

[0028] d) introducing the ethylbenzene-containing product stream (80, 270) thus obtained in c.1) or c.2) into an ethylbenzene distillation column (D1), thereby recovering a distilled ethylbenzene stream (110) from the top of the column and a stream (120) containing α-methylbenzyl alcohol from the bottom;

[0029] e) introducing the ethylbenzene product stream (110) into an ethylbenzene oxidation unit, optionally together with fresh ethylbenzene (100), to produce ethylbenzene hydroperoxide by liquid phase oxidation;

[0030] f) reacting the ethylbenzene hydroperoxide obtained in e) with a propylene stream in the presence of a catalyst in an epoxidation unit to produce crude propylene oxide (300) and a bottom product (310) containing ethylbenzene and α-methylbenzyl alcohol;

[0031] g) feeding the stream containing α-methylbenzyl alcohol (120) to a second distillation column (D2) to obtain three fractions: a product stream tops (130) containing xylenes, a side stream (150) rich in α-methylbenzyl alcohol and a bottoms stream (140) containing α-methylbenzyl alcohol and higher boiling products;

[0032] Alternatively, the stream (120) containing α-methylbenzyl alcohol is introduced into a second distillation column (D2), and a stream product top distillate (130) containing xylenes and a bottom stream introduced into an additional distillation column (D2') are separated to obtain a top stream (150) rich in α-methylbenzyl alcohol and a heavy bottom stream (140) containing α-methylbenzyl alcohol and higher boiling point products;

[0033] h) introducing the side stream (150) rich in α-methylbenzyl alcohol into a dehydration unit (DH1) containing a catalyst, thereby obtaining a phase-separated crude styrene monomer (160) and water;

[0034] i) feeding the crude styrene phase (160) thus obtained to a distillation column (D3), in which a stream (170) containing ethylbenzene is separated from the top, and the bottom product (180) is fed to a styrene product column (D4), in which styrene monomer (190) is obtained at the top and heavy products (200) are obtained at the bottom;

[0035] j) feeding the heavy bottom product streams (140 and 200) from the second distillation column and the additional distillation columns (D2, D2') and the styrene product column (D4) to a distillation column (D5); the distilled product stream (220) thus obtained together with the ethylbenzene-containing stream (170) to the hydroprocessing unit (HP) of step c).

[0036] Steps d) to j) correspond to the current propylene oxide / styrene monomer (PO / SM) co-production process described in the prior art (see, for example, Propylene Oxide PERP 2012-7, pages 19-26). Details are given in the specific embodiment to understand the meaning of introducing the hydrocarbon liquid stream produced by the pyrolysis of waste plastics as described above in step c). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Non-limiting embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0038] Figure 1A A schematic diagram of step b.1) is shown.

[0039] Figure 1B A schematic diagram of step b.2) is shown.

[0040] Figure 1C A schematic diagram of step b.3) is shown.

[0041] Figure 2A A schematic diagram of step c.1A) is shown.

[0042] Figure 2B A schematic diagram of a general PO / SM process comprising steps b.1) + c.1A) is shown.

[0043] Figure 3A A schematic diagram of step c.1B) is shown.

[0044] Figure 3B A schematic diagram of a general PO / SM process comprising steps b.1) + c.1B) according to Example 1 of the present invention is shown.

[0045] Figure 4A A schematic diagram of step c.2) is shown.

[0046] Figure 4B A schematic diagram of a general PO / SM process comprising steps b.1) + c.2) according to Example 2 of the present invention is shown.

[0047] Figure 5A A schematic diagram of the MBA distillation step using one distillation column D2 is shown.

[0048] Figure 5BA schematic diagram of the MBA distillation step using two distillation columns D2+D2' is shown.

[0049] Figure 6 A schematic diagram of a general PO / SM process is shown (Comparative Example 1).

[0050] Figure 7 A schematic diagram of Comparative Example 2 is shown.

[0051] Figure 8 A schematic diagram of Comparative Example 3 is shown. DETAILED DESCRIPTION

[0052] Unless otherwise specified, all terms used in this application should be understood with their ordinary meanings known in the art. Other more specific definitions of certain terms used in this application are described below and are intended to be uniformly applied throughout the specification and claims, unless otherwise explicitly stated definitions provide a broader definition.

[0053] For the purposes of the present invention, any given range includes the lower and upper limits of that range. Unless otherwise indicated, the ranges and values ​​(eg, temperatures, times, etc.) given should be considered approximate.

[0054] The terms "weight percent (%)" or "percent (%) w / w" or "% wt" have the same meaning and are used interchangeably. This term refers to the percentage of a component in the total weight.

[0055] Unless otherwise indicated, for purposes of this disclosure the term "amount" refers to the weight percent of a given component in a particular composition based on the total weight of the particular composition (eg, the total weight of all components present in the particular composition).

[0056] The terms "a", "an" and "the" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. As used herein, the singular forms "a", "an" and "the" include plural referents.

[0057] As used herein, the term "about" or "approximately" refers to a value within a range of ±10% of a particular value. For example, the expression "about 25" or "approximately 25" includes ±10% of 25, i.e., from 22.5 to 27.5.

[0058] For the purposes of the present invention, unless expressly stated otherwise, the terms methylstyrene, ethylstyrene and xylene encompass ortho-, meta- and para-isomers. The plural forms of alkane, alkene and alkyne terms in the present invention mean that they encompass all possible positional isomers and stereoisomers thereof. For example, the term pentene encompasses 1-pentene, 2-cis-pentene and 2-trans-pentene; the term methylbutene encompasses 2-methyl-2-butene, 2-methyl-1-butene and 3-methyl-1-butene.

[0059] For the purpose of the present invention, the expressions “available”, “obtained” and the like and their equivalents are used interchangeably, and in any case, the expressions “available” and the like encompass the expressions “obtained” and the like.

[0060] Furthermore, for purposes of the present invention, when the stereoselectivity and regioselectivity of the term (compound) is not specifically disclosed, it is to be understood that the term encompasses all stereoisomers and positional isomers. Thus, for purposes of the present invention, the term "methylstyrene" includes 1-methyl-2-vinylbenzene (o-methylstyrene), 1-methyl-3-vinylbenzene (m-methylstyrene), 1-methyl-4-vinylbenzene (p-methylstyrene),

[0061] The term "polystyrene" refers to a polymer comprising styrene monomer (SM; or C6H5CH=CH2) having the following molecular formula:

[0062]

[0063] The term "polystyrene" includes both homopolymers of styrene monomers and copolymers of styrene monomers with other monomers, and therefore, for the purposes of the present invention, the term polystyrene includes all grades of pure polystyrene, styrene copolymers, and mixtures thereof. In one embodiment, the polystyrene is a residue (waste) containing polystyrene. Examples of styrene-containing polymers suitable for use in the present invention include, but are not limited to, high impact polystyrene (HIPS), styrene acrylonitrile (SAN), acrylonitrile butadiene styrene (ABS), general purpose polystyrene (GPPS), and expanded polystyrene foam (EPS).

[0064] The term (C1-Cn) alkyl refers to a saturated branched or straight hydrocarbon chain containing 1 to n carbon atoms and only single bonds. The term (C2-Cn) alkenyl refers to a branched or straight hydrocarbon chain containing 2 to n carbon atoms and at least one carbon-carbon double bond. The term (C2-Cn) alkynyl refers to a branched or straight hydrocarbon chain containing 2 to n carbon atoms and at least one carbon-carbon triple bond. The term (C5-Cn) cycloalkyl refers to a cyclic hydrocarbon containing 5 to n carbon atoms and only single bonds. The term (C5-Cn) cycloalkenyl refers to a cyclic hydrocarbon containing 5 to n carbon atoms and at least one carbon-carbon double bond.

[0065] The terms "alkane" and "cycloalkane" refer to saturated straight-chain, branched, linear or cyclic hydrocarbons (optionally branched) containing the number of carbon atoms specified in the specification or claims. Examples include methane, ethane, n-butane, isobutane, pentane, hexane, methylbutane, heptane, octane and cyclopentane.

[0066] The term "olefin" refers to a straight chain hydrocarbon, optionally with branches, containing the number of carbon atoms specified in the specification or claims, and also containing at least one carbon-carbon double bond. Examples include vinyl, 2-propenyl and 1-propenyl, etc. Examples include 2-methyl-1-butene, pentene, heptene, hexene and isobutylene.

[0067] The term "cycloolefin" refers to a cyclic hydrocarbon, optionally branched, containing the number of carbon atoms specified in the specification or claims and containing at least one carbon-carbon double bond. Examples include cyclopentene, cyclohexene, methylcyclohexene, dimethylcyclohexene, 1,3-dimethylcyclopentadiene and cyclopentadiene.

[0068] The plural forms of alkanes, alkenes and alkynes in the present invention are intended to cover all possible positional isomers and stereoisomers thereof. For example, the term "pentene" covers 1-pentene, 2-cis-pentene and 2-trans-pentene; the term methylbutene covers 2-methyl-2-butene, 2-methyl-1-butene and 3-methyl-1-butene.

[0069] The term "aromatic compound" refers to an organic compound containing one or more rings with delocalized π electrons around them and containing the number of carbon atoms specified in the specification or claims. Aromatic compounds can be optionally substituted with one or more moieties, such as (C1-C6) alkyl, (C2-C6) alkenyl, and (C2-C6) alkynyl. In one embodiment, the aromatic compound is a phenyl optionally substituted with (C1-C6) alkyl, (C2-C6) alkenyl, and (C2-C6) alkynyl. The term "alkyl" refers to a saturated straight-chain hydrocarbon substituent, optionally with a branched chain, containing the number of carbon atoms specified in the specification or claims. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl, etc. The term "alkenyl" refers to a straight-chain hydrocarbon substituent, optionally with a branched chain, containing the number of carbon atoms specified in the specification or claims, and also containing at least one carbon-carbon double bond.

[0070] The term "alkynyl" refers to a straight chain hydrocarbon substituent, optionally branched, having the number of carbon atoms specified in the specification or claims, and also containing at least one carbon-carbon triple bond.

[0071] In one embodiment, the aromatic compound is selected from the group consisting of C8 aromatic compounds, C9 aromatic compounds and C10 aromatic compounds. Examples of C8 aromatic compounds include ethylbenzene, o-xylene, m-xylene and p-xylene, phenylacetylene. Examples of C9 aromatic compounds include isopropylbenzene, propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene. Examples of C10 aromatic compounds include divinylbenzene and ethylstyrene.

[0072] The term "heavy oil fraction" or "heavy fraction-containing stream" refers to a mixture having an initial standard boiling point of 200° C. and an end standard boiling point of 400° C. It contains one or more of the following compounds: indene, naphthalene, phthalide, tetralin, 2,4-diphenyl-1-butene, 1,4-diphenyl-1,3-butadiene, 2,4,6-triphenyl-1-hexene, biphenyl, bibenzyl, methylnaphthalene, 2-phenylnaphthalene, diphenylmethane, dimer, trimer, stilbene, etc. In general, the heavy fraction-containing stream (20) may also be referred to as a C9+-containing stream.

[0073] The term "acid-containing compound" refers to a compound that contains one or more acid moieties. It includes organic carboxylic acids and inorganic acids. Examples include hydrochloric acid, hydrobromic acid, benzoic acid, acetic acid, and propionic acid, among others.

[0074] The term "metal" includes, for example, calcium, potassium, silicon, aluminum, sodium, magnesium, titanium, iron, zinc, and the like.

[0075] The term "heteroatom" includes halogens (eg, chlorine, fluorine and bromine), sulfur, nitrogen and oxygen. The term "heteroatom-containing compound" includes compounds containing at least one or more heteroatoms as defined above.

[0076] For the purpose of the present invention, the terms "hydrocarbon liquid stream obtained from polystyrene waste plastics", "pyrolysis oil of polystyrene", "polystyrene pyrolysis oil" and "pyrolysis oil" have the same meaning and are used interchangeably. They refer to an oil mixture containing 50% to 98% styrene monomer obtained by pyrolysis of polystyrene as defined above. Pyrolysis is a mature technology for decomposing organic matter into oil and other components at high temperatures (especially above its decomposition temperature) in an inert atmosphere (without oxygen). Pyrolysis oil suitable for the present invention and its preparation method have been widely disclosed in the prior art. Examples can be found in the following literature: Ki-bum Park et al., "Two-stage pyrolysis of polystyrene: Pyrolysis oil as a source of fuel or benzene, toluene, ethylbenzene, and xylenes", Applied Energy 259, 2020, pp. 114-240; Ibrahim M. Maafa, "Pyrolysis of Polystyrene Waste: A review", Polymers, 2021, Vol. 13, p. 225; John Scheirs and Walter Kaminsky, "Feedstock Recycling and Pyrolysis of Waste Plastics: Converting Waste Plastics into Diesel and Other Fuels", Wiley Online Library, 2006, p. 635; and Jasmin Shah et al., "Conversion of waste polystyrene through catalytic degradation into valuable products", Korean J. Chem. Eng., 2014, Vol. 31(8), pp. 1389-1398; US10301235, WO2021230312 and WO2021053074.

[0077] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the polystyrene pyrolysis oil contains 50 wt% to 98 wt% of styrene monomer by subjecting one or more polystyrene compounds and / or one or more polystyrene-containing compounds, in particular polystyrene rich in styrene monomer, to a pyrolysis reaction (see, for example, US10301235, WO2021230312 and WO2021053074).

[0078] According to one embodiment, optionally in combination with one or more features of a specific embodiment defined herein, the hydrocarbon liquid stream produced by pyrolysis of waste plastic is a pyrolysis oil stream produced by converting waste plastic (preferably waste plastic rich in polystyrene) into a pyrolysis oil stream and a solid residue (char) in a pyrolysis unit.

[0079] According to another embodiment, optionally in combination with one or more features of specific embodiments defined herein, in the method, the hydrocarbon liquid stream (10) is a pyrolysis oil comprising:

[0080] - 50 to 98% by weight of styrene monomer and ethylbenzene, preferably 60 to 98% by weight, more preferably 70 to 98% by weight, even more preferably 80 to 98% by weight;

[0081] - 0 to 9% by weight of α-methylstyrene, preferably 0.01 to 8% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight;

[0082] - 0 to 1% by weight of phenylacetylene, preferably 0.001 to 1% by weight, more preferably 0.01 to 1% by weight, even more preferably 0.1 to 1% by weight;

[0083] - 0 to 15% by weight of toluene, preferably 1 to 12% by weight, more preferably 2 to 10% by weight, even more preferably 2 to 8% by weight;

[0084] - 0 to 5% by weight of benzene, preferably 0.1 to 4% by weight, more preferably 0.5 to 4% by weight, even more preferably 0.5 to 2% by weight;

[0085] - 0 to 2.5% by weight of C8 aromatic compounds other than styrene monomer and ethylbenzene, which is a mixture of o-xylene, m-xylene and p-xylene, preferably 0 to 2% by weight, more preferably 0.1% to 1.5% by weight, even more preferably 0.1% to 1% by weight;

[0086] - 0 to 5% by weight of C9 aromatic compounds other than α-methylstyrene, which is a mixture of isopropylbenzene, β-methylstyrene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene, preferably 0.001 to 3% by weight, more preferably 0.01 to 2% by weight, even more preferably 0.1 to 1% by weight;

[0087] - 0 to 5% by weight of a C10 aromatic compound which is a mixture of divinylbenzene and ethylstyrene, preferably 0.001 to 3% by weight, more preferably 0.01 to 2% by weight, even more preferably 0.1 to 1% by weight;

[0088] - 0 to 2% by weight of one or more compounds selected from the group consisting of mixtures of (C3-C8)alkanes, (C3-C8)alkenes, (C5-C8)cycloalkanes and (C5-C8)cycloalkenes, preferably 0.001 to 1.5% by weight, more preferably 0.01 to 1% by weight; even more preferably 0.1 to 0.8% by weight;

[0089] - 0.05 to 15% by weight of heavy oil fraction, preferably 0.1 to 10% by weight, more preferably 0.5 to 8% by weight, even more preferably 1 to 5% by weight;

[0090] - 0 to 50 ppm by weight of metal-containing metal compounds, preferably 1 to 25 ppm by weight, more preferably 5 to 10 ppm by weight;

[0091] - 0.5 to 5000 ppm by weight of heteroatoms of heteroatom-containing compounds, preferably 1 to 2500 ppm by weight, more preferably 5 to 100 ppm by weight, even more preferably 10 to 500 ppm by weight; and

[0092] 0 to 1 wt. % water, preferably 0.001 to 0.1 wt. %, more preferably 0.005 to 0.05 wt. %, even more preferably 0.01 to 0.025 wt. %.

[0093] According to another embodiment, optionally in combination with one or more features of specific embodiments defined herein, in the method, the hydrocarbon liquid stream (10) is a pyrolysis oil comprising:

[0094] - 50 to 98% by weight of styrene monomer and ethylbenzene;

[0095] - 0 to 9% by weight of α-methylstyrene;

[0096] - 0 to 1% by weight of phenylacetylene;

[0097] - 0 to 15% by weight of toluene;

[0098] - 0 to 5% by weight of benzene;

[0099] - 0 to 2.5% by weight of C8 aromatic compounds other than styrene monomer and ethylbenzene, including o-xylene, m-xylene and p-xylene;

[0100] - 0 to 5% by weight of C9 aromatic compounds other than α-methylstyrene, including cumene, β-methylstyrene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene;

[0101] - 0 to 5% by weight of C10 aromatic compounds, including divinylbenzene and ethylstyrene;

[0102] - 0 to 2% by weight of one or more compounds selected from the group consisting of (C3-C8)alkanes, (C2-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0103] - 0.05 to 15% by weight of heavy oil fraction;

[0104] - 0 to 50 ppm by weight of metal-containing metal compounds;

[0105] - 0.5 ppm by weight to 5000 ppm by weight of heteroatoms of heteroatom-containing compounds; and

[0106] - 0 to 1% by weight of water.

[0107] According to another embodiment, optionally in combination with one or more features of specific embodiments defined herein, in the method, the hydrocarbon liquid stream (10) is a pyrolysis oil comprising:

[0108] - 60 to 98% by weight of styrene monomer and ethylbenzene;

[0109] - 0.1 to 5% by weight of α-methylstyrene;

[0110] - 0.01 to 1% by weight of phenylacetylene;

[0111] - 2 to 10% by weight of toluene;

[0112] - 0.5 to 4% by weight of benzene;

[0113] - 0.1 to 1.5% by weight of C8 aromatic compounds, including in particular ethylbenzene, o-xylene, m-xylene and p-xylene;

[0114] - 0.01 to 2% by weight of C9 aromatic compounds, in particular including cumene, propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene;

[0115] - 0.01 to 2% by weight of C10 aromatic compounds, including in particular divinylbenzene and ethylstyrene;

[0116] - 0.01% to 1% by weight of one or more compounds selected from the group consisting of (C3-C8)alkanes, (C2-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0117] - 0.5 to 8% by weight of heavy oil fraction;

[0118] - 5 to 10 ppm by weight of metal-containing metal compounds;

[0119] - 10 ppm to 500 ppm of heteroatoms of heteroatom-containing compounds; and

[0120] - 0.01 to 0.025% by weight of water.

[0121] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the method wherein the hydrocarbon liquid stream (10) is a pyrolysis oil as defined above, further comprising 0.005 to 3 mgKOH / g of acid-containing compounds, preferably 0.01 to 1 mgKOH / g of acid-containing compounds, measured by standard test method ASTM D664.

[0122] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the process wherein the hydrocarbon liquid stream (10) is a pyrolysis oil as defined above, comprising from 0.1 ppm to 50 ppm of metals, preferably from 0.1 ppm to 5 ppm, as measured by methods EPA 3051a and ASTM D6052-97.

[0123] The term "heavy oil fraction" refers to a mixture having an initial normal boiling point of 200° C. and an end normal boiling point of 400° C. It contains one or more of the following compounds: indene, naphthalene, tetralin, 2,4-diphenyl-1-butene, 1,4-diphenyl-1,3-butadiene, 2,4,6-triphenyl-1-hexene, biphenyl, bibenzyl, methylnaphthalene, 2-phenylnaphthalene, diphenylmethane, diphenylethylene, and the like.

[0124] The term "acid-containing compound" refers to a compound that contains one or more acid moieties. It includes organic carboxylic acids and inorganic acids. Examples include hydrochloric acid, hydrobromic acid, benzoic acid, acetic acid, and propionic acid, among others.

[0125] The term "metal" includes, for example, calcium, potassium, silicon, aluminum, sodium, magnesium, titanium, iron, zinc, and the like.

[0126] In addition to the pyrolysis oil stream, any hydrocarbon liquid stream resulting from the treatment of waste plastics comprising the composition as defined above may also be used in the process of the present invention.

[0127] According to another embodiment, optionally in combination with one or more features of a specific embodiment defined herein, the method further comprises the previous step, wherein, in a pyrolysis unit configured to convert waste plastic into pyrolysis products through a pyrolysis process, wherein the pyrolysis products comprise a gas phase and a solid phase (char), and the gas phase is partially condensed into a liquid phase (pyrolysis oil) and a non-condensable gas phase, wherein the non-condensable gas phase comprises pyrolysis gases, such as C1 to C4 hydrocarbons, hydrogen, carbon monoxide, carbon dioxide, hydrogen chloride gas, and the like.

[0128] The waste plastics that can be loaded or fed into the pyrolysis unit can include post-consumer waste plastics, such as mixed waste plastics. Mixed plastics can include non-chlorinated plastics (e.g., polyolefins, polyethylene, polypropylene, polystyrene, copolymers, etc.), chlorinated plastics (e.g., polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), etc.), etc., or mixtures thereof. Preferably, the waste plastics contain a high polystyrene content.

[0129] The pyrolysis unit can be any suitable container, which is configured to convert waste plastics into gas phase and solid phase (charcoal) products (for example, at the same time), and the gas phase is partially condensed in the liquid phase. The container can be configured to operate in gas phase, liquid phase, steam-liquid phase, gas-solid phase, liquid-solid phase or slurry phase. The container can include one or more inert materials or pyrolysis catalyst beds, such as sand, zeolite, alumina, catalytic cracking catalyst or a combination thereof. Typically, the pyrolysis catalyst is able to transfer heat to the components that undergo the pyrolysis process in the pyrolysis unit. Alternatively, the pyrolysis unit can be operated without any catalyst (for example, pure pyrolysis). The pyrolysis unit can be operated in adiabatic, isothermal, non-adiabatic, non-isothermal or a combination thereof. The pyrolysis reaction can be carried out in a single stage or in multiple stages. For example, the pyrolysis unit can be a reaction vessel in which more than two fluids are connected in series.

[0130] Step b) - Pretreatment of the hydrocarbon liquid stream (10)

[0131] In the method according to the invention, step b) can be carried out according to 3 different alternatives, namely:

[0132] b.1) wherein the hydrocarbon liquid stream (10) is introduced into a first fractionation unit (T1) - see Figure 1A ;

[0133] b.2) wherein the hydrocarbon liquid stream (10) is introduced into a first fractionation unit (T1) to separate a C7 stream overhead (40) and a stream introduced into a second fractionation unit (T1') - see Figure 1B ;

[0134] or

[0135] b.3) wherein the hydrocarbon liquid stream (10) is introduced into a distillation column (D5) without prior fractionation in any fractionation unit (T1 or T1') to obtain a distilled product stream (220) - see Figure 1C .

[0136] Thus, according to option b.1), the hydrocarbon liquid stream (10) is introduced into a first fractionation unit (T1) to separate a C7 stream tops (40), a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a product second side stream (50) containing alpha-methylstyrene - see Figure 1A .

[0137] According to option b.2), the hydrocarbon liquid stream (10) is introduced into a first fractionation unit (T1) to separate a C7 stream overhead (40) and a stream introduced into a second fractionation unit (T1') which is introduced into the second fractionation unit (T1') to obtain a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a product side stream (50) containing alpha-methylstyrene - see Figure 1B .

[0138] According to option b.3), the hydrocarbon liquid stream (10) is introduced into a distillation column (D5) without prior fractionation in any fractionation unit (T1 or T1'), thereby obtaining a distilled product stream (220); the distilled product stream (220) is then sent to the hydrotreatment unit (HP) of step c.1) - see Figure 1C .

[0139] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the first fractionated side stream (30) comprises a benzene content of 0 to 500 ppm by weight, preferably 0 to 250 ppm by weight.

[0140] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the first fractionated side stream (30) contains styrene and ethylbenzene in a content of 89% to 99% by weight, preferably 92% to 99% by weight, more preferably 95% to 98.9% by weight, as the sum of the weight contents of the two components, relative to the total weight of the stream.

[0141] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the first fractionated side stream (30) obtained according to option b1) or option b2) contains a content of styrene and ethylbenzene as the sum of the weight contents of the two components of 89% to 99% by weight, preferably 92% to 99% by weight, more preferably 95% to 98.9% by weight, relative to the total weight of the stream, and a benzene content of 0 to 250 ppmw relative to the total weight of the stream.

[0142] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the first fractionated side stream (30) obtained according to option b1) or option b2) comprises 0.01 to 1 mgKOH / g of acid containing compounds measured by standard test method ASTM D664.

[0143] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the first fractionated side stream (30) obtained according to option b1) or option b2) comprises 0 to 1 ppm F, 0 to 5 ppm Cl, 0 to 5 ppm Br and 0 to 500 ppm N.

[0144] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the first fractionated side stream (30) obtained according to option b1) or option b2) comprises:

[0145] i. 89 to 99% by weight of styrene monomer and ethylbenzene, preferably 90 to 98% by weight, more preferably 93 to 95% by weight;

[0146] ii. 0 to 500 ppm by weight of benzene, preferably 50 to 300 ppm by weight, more preferably 100 to 250 ppm by weight;

[0147] iii. 0 to 1 wt% toluene, preferably 0.01 to 0.5 wt%, more preferably 0.1 to 0.3 wt%;

[0148] iv. 0 to 2.5 wt% of xylene, preferably 0.1 to 2 wt%, more preferably 0.5 to 1.5 wt%;

[0149] v. 0 to 1.5% by weight of a C9 aromatic compound other than α-methylstyrene, which is a mixture of cumene, propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene, preferably 0.01 to 1% by weight, more preferably 0.1 to 0.8% by weight;

[0150] vi. 0 to 5% by weight of α-methylstyrene, preferably 0.1 to 3% by weight, more preferably 1% by weight

[0151] % to 2.5% by weight;

[0152] vii. 0 to 1.5 wt% of phenylacetylene, preferably 0.0001 to 1 wt%, more preferably 0.001 to 0.5 wt%;

[0153] viii. 0 to 2500 ppm by weight of heteroatom-containing compounds, preferably 1 to 1250 ppm by weight, more preferably

[0154] Select 10 to 250 ppm by weight;

[0155] ix. 0 to 0.1 wt% of a C10 aromatic compound which is a mixture of divinylbenzene and ethylstyrene, preferably 0.001 to 0.08 wt%, more preferably 0.01 to 0.05 wt%;

[0156] x. 0 to 1% by weight of one or more compounds selected from the group consisting of (C3-C8)alkanes, (C2-C8)olefins,

[0157] A mixture of (C5-C8)cycloalkanes and (C5-C8)cycloalkenes, preferably 0.001 wt% to 0.85 wt%, more preferably

[0158] Select 0.01 wt % to 0.5 wt %;

[0159] xi. 0 to 0.1 wt% of heavy oil fraction, preferably 0.0001 to 0.05 wt%, more preferably 0.001 to 0.01 wt%;

[0160] xii. 0 to 50 ppm by weight of the metal-containing metal compound, preferably 0.01 to 25 ppm by weight, more preferably

[0161] Preferably 0.1 to 10 ppm by weight;

[0162] xiii. 0.5 to 1500 ppm by weight of heteroatoms of heteroatom-containing compounds, preferably 1 to 500 ppm by weight

[0163] Amount, more preferably 5 to 100 ppm by weight; and

[0164] xiv. 0 to 120 ppm by weight of water, preferably 0.1 to 25 ppm by weight, more preferably 1 to 10 ppm by weight.

[0165] Option b.1) - Pretreatment of the hydrocarbon liquid stream (10) with a fractionation unit (T1) - see Figure 1A

[0166] According to one embodiment, option b.1) is optionally combined with one or more features of the specific embodiments defined herein, step b) is carried out in a first fractionation unit (T1) to separate a C7 stream top distillate (40), a first fractionation side stream (30), a heavy fraction containing stream from the bottom (20) and optionally a second side stream (50) containing α-methylstyrene product.

[0167] According to this embodiment, the first fractionation unit (T1) can be a packed distillation column, a tray distillation column or a combination thereof. The column can be operated at a vacuum pressure (e.g. 13 to 65 kPa) and a bottom section temperature of 180°C, such as 15 to 50 kPa, such as 20 to 35 kPa. The temperature can be greater than or equal to 90°C, such as greater than or equal to 130°C, such as greater than or equal to 175°C.

[0168] The top (40) of the column consists of benzene, toluene, water, certain components belonging to the feed oil fraction having a higher volatility than styrene monomer, (C3-C8) alkanes, (C2-C8) olefins, (C5-C8) cycloalkanes and (C5-C8) cycloolefins, certain acid-containing compounds and heteroatom-containing compounds in the feed oil having a higher volatility than styrene monomer, and part of the ethylbenzene in the feed oil. The top vapor stream leaving the column can be partially or fully condensed by a top condensing unit operating with an external cooling medium, or by using a top condensing unit operating with an external cooling medium (e.g., cooling water), which partially condenses the vapor stream, separates the obtained mixed vapor / liquid stream in a subsequent reflux drum, and condenses the separated vapor stream leaving the reflux drum by using a second condensing unit using an external cooling medium (e.g., cooling water) having a lower temperature than the first condensing unit. The non-condensable gases leave a vacuum unit, which can be of any commercially available type, such as a steam ejector. Part of the condensed liquid is refluxed to the column, and the remainder produces a fractionated C7 stream (40). Any aqueous phase separated in the reflux drum is removed as a product stream.

[0169] Styrene and ethylbenzene can be removed as a top stage side product stream (30). This stream can also remove part or all of the xylene and phenylacetylene, part of the α-methylstyrene and other C9 aromatic compounds, part of the acid-containing compounds and heteroatom-containing compounds, part of the metal-containing compounds, and certain components (C3-C8) alkanes, (C2-C8) alkenes, (C5-C8) cycloalkanes and (C5-C8) cycloalkenes belonging to the feed oil fraction having a volatility similar to that of styrene monomer.

[0170] α-Methylstyrene can be removed as a lower stage side product stream (50). This stream can also remove a portion of C9 aromatic compounds other than α-methylstyrene, a portion of C10 aromatic compounds, a portion of acid-containing compounds and heteroatom-containing compounds, and a portion of metal-containing compounds.

[0171] The heavy oil fraction can be removed as the bottom product of the column (20). This stream can also remove a portion of the C9 aromatic compounds and α-methylstyrene, a portion or all of the C10 aromatic compounds, a portion of the acid-containing compounds and the heteroatom-containing compounds, and a portion of the metal-containing compounds. This stream can also be used to provide the latent heat required for evaporation. For example, by using a bottom reboiler unit, which can be of any type available in the industry, such as a forced circulation reboiler.

[0172] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the fractionation unit (T1) comprises at least one distillation tower with trays, the distillation tower comprising 20 to 60 theoretical stages (stage 1 - the top of the tower); wherein the feed to the distillation tower is located at a position between 60% and 65% of the total theoretical stages of the distillation tower; wherein the first fractionated pyrolysis oil side stream (30) is obtained through a side outlet of the distillation tower located at a position between 35% and 45% of the total theoretical stages of the distillation tower; wherein the second fractionated pyrolysis oil side stream (50) is obtained through a side outlet of the distillation tower located at a position between 85% and 95% of the total theoretical stages of the distillation tower.

[0173] Option b.2) - Pretreatment of the hydrocarbon liquid stream (10) using two fractionation units (T1+T1') - see Figure 1B

[0174] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, step b) is carried out by introducing the hydrocarbon liquid stream into a first fractionation unit (T1) to separate a C7 stream top distillate (40) and a side stream introduced into a second fractionation unit (T1'), wherein the side stream is introduced into the second fractionation unit (T1') to obtain a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a side stream containing an α-methylstyrene product (50).

[0175] According to this embodiment, the first fractionation unit (T1) can be a packed distillation column, a tray distillation column or a combination thereof. The column can be operated at a vacuum pressure (e.g. 13 to 50 kPa) and a bottom temperature of 105°C, such as 15 to 30 kPa, such as 20 to 30 kPa. The temperature can be greater than or equal to 80°C, such as greater than or equal to 90°C, such as greater than or equal to 105°C.

[0176] The top of the tower consists of benzene, toluene, water, certain components belonging to the feed oil fraction having a higher volatility than styrene monomer, (C3-C8) alkanes, (C2-C8) olefins, (C5-C8) cycloalkanes and (C5-C8) cycloolefins, certain acid-containing compounds and heteroatom-containing compounds in the feed oil having a higher volatility than styrene monomer, and part of the ethylbenzene in the feed oil. The top vapor stream leaving the tower is partially or fully condensed by a top condensing unit operating with an external cooling medium, or by using a top condensing unit operating with an external cooling medium (e.g., cooling water), which partially condenses the vapor stream, separates the obtained mixed vapor / liquid stream in a subsequent reflux drum, and condenses the separated vapor stream leaving the reflux drum by using a second condensing unit using an external cooling medium (e.g., cooling water) having a lower temperature than the first condensing unit. The non-condensable gases leave a vacuum unit, which can be of any commercially available type, such as a steam ejector. Part of the condensed liquid is refluxed into the tower, and the remainder produces a fractionated C7 stream (40). Any aqueous phase separated in the reflux drum is taken off as a product stream. The remainder of the total mass of oil fed to T1 flows out of the bottom of T1 and is fed to T1'. This stream can also be used to provide the latent heat required for evaporation. For example, by using a bottom reboiler unit, which can be of any type available industrially, such as a forced circulation reboiler.

[0177] The second fractionation unit (T1') can be a packed distillation column, a tray distillation column or a combination thereof. The column can be operated at a vacuum pressure (e.g. 13 to 65 kPa) and a bottom temperature of 180°C, such as 15 to 50 kPa, such as 20 to 35 kPa. The temperature can be greater than or equal to 90°C, such as greater than or equal to 130°C, such as greater than or equal to 175°C.

[0178] Styrene and ethylbenzene can be removed as a top product stream (30). This stream can also remove some or all of the xylenes and phenylacetylene, some alpha-methylstyrene and other C9 aromatic compounds, some acid-containing compounds and heteroatom-containing compounds, some metal-containing compounds, and certain components of the feed oil fraction (C3-C8) alkanes, (C2-C8) olefins, (C5-C8) cycloalkanes and (C5-C8) cycloolefins that have similar volatility to styrene monomer. The top vapor stream leaving the tower is partially or completely condensed by a top condensing unit operating with an external cooling medium, or by using a top condensing unit operating with an external cooling medium (e.g., cooling water), which partially condenses the vapor stream, separates the resulting mixed vapor / liquid stream in a subsequent reflux drum, and condenses the separated vapor stream leaving the reflux drum by using a second condensing unit using an external cooling medium (e.g., cooling water) at a lower temperature than the first condensing unit. The non-condensable gases leave a vacuum unit, which can be of any commercially available type, such as a steam ejector. Part of the condensed liquid is refluxed to the column and the remainder produces a fractionated product stream (30).

[0179] α-Methylstyrene can be removed as a lower stage side product stream (50). This stream can also remove a portion of C9 aromatic compounds other than α-methylstyrene, a portion of C10 aromatic compounds, a portion of acid-containing compounds and heteroatom-containing compounds, and a portion of metal-containing compounds.

[0180] The heavy oil fraction can be removed as the bottom product of the column (20). This stream can also remove a portion of the C9 aromatic compounds and α-methylstyrene, a portion or all of the C10 aromatic compounds, a portion of the acid-containing compounds and the heteroatom-containing compounds, and a portion of the metal-containing compounds. This stream can also be used to provide the latent heat required for evaporation. For example, by using a bottom reboiler unit, which can be of any type available in the industry, such as a forced circulation reboiler.

[0181] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the fractionation unit (T1) comprises at least one distillation column with trays, the distillation column comprising 10 to 30 theoretical stages (stage 1 - top of the column); wherein the feed to the distillation column is located at a position between 50% and 70% of the total theoretical number of stages of the distillation column.

[0182] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the fractionation unit (T1') comprises at least one distillation tower with trays, the distillation tower comprising 15 to 40 theoretical stages (stage 1 - top of the tower); wherein the feed to the distillation tower is located at a position between 40% and 60% of the total theoretical number of plates of the distillation tower; and wherein the fractionated pyrolysis oil side stream (50) is obtained through a side outlet of the distillation tower located at a position between 85% and 95% of the total theoretical number of stages of the distillation tower.

[0183] Option b.3) - Pre-treating the hydrocarbon liquid stream (10) using a distillation column (D5) - see Figure 1C

[0184] According to option b.3), the hydrocarbon liquid stream (10) produced by pyrolysis of waste plastics is directly introduced into the distillation column (D5) without prior fractionation in any fractionation unit (T1 or T1'), thereby obtaining a distilled product stream (220).

[0185] The distilled product stream (220) requires further hydrogenation. Therefore, the distilled product stream (220) is then sent to the hydroprocessing unit (HP) of step c.1) - see Figure 1C .

[0186] Step c) - Hydrogenation

[0187] In the process according to the invention, step c) can be carried out according to 2 different alternatives, namely:

[0188] c.1) wherein the first fractionated pyrolysis oil side stream (30) obtained in b.1) or b.2) or the distilled product stream (220) obtained in b.3) is introduced into a hydroprocessing unit (HP) comprising a hydroprocessing catalyst in the presence of hydrogen;

[0189] or,

[0190] c.2) wherein the first fractionated pyrolysis oil side stream (30) obtained in b.1) or b.2) is introduced into a distillation column (D5), and the resulting distilled product stream (220) is then fed to the hydroprocessing unit (HP) of step c.1).

[0191] Furthermore, depending on the hydroprocessing unit used in alternative c.1), different alternatives can be considered:

[0192] c.1A) (See Figure 2A and 2B ) The hydroprocessing unit is a dedicated hydroprocessing unit (HP2) which may contain one or more hydrogenation reactors (HP2 1 HP2 2 , ..., HP2n ); i.e., different from the hydroprocessing unit (HP) used for ACP hydrogenation;

[0193] c.1B) (See Figure 3A and 3B ), the hydroprocessing unit is the same hydroprocessing unit (HP1) as used in the ACP hydrogenation step of the standard PO / SM process (the standard PO / SM process is as follows Figure 6 As shown), wherein the first fractionation side stream (30) is introduced into the hydroprocessing unit (HP1) together with the product stream distilled from the distillation tower (D5).

[0194] The skilled person can routinely apply the specific conditions according to methods known in the art, based on technical information in common knowledge. Thus, for example, the hydroprocessing unit (HP1) may include at least one slurry hydrogenation reactor or at least one fixed bed reactor. According to one embodiment, the hydroprocessing unit (HP1) includes one slurry hydrogenation reactor (HP1); or may include two or more slurry hydrogenation reactors (HP1 1 、HP1 2 ...HP1 n ).

[0195] Therefore, in the method of the present invention, step c) can be carried out according to the following alternatives:

[0196] c.1) The first fractionated side stream (30) obtained in b.1) or b.2) or the distilled product stream (220) obtained in b.3) is introduced into a hydrotreatment unit (HP).

[0197] The first alternative c.1) consists of two different options:

[0198] c.1A. Dedicated Hydroprocessing Unit (HP2) - Reference Figure 2A and 2B .

[0199] According to this embodiment, the first fractionated side stream (30) is contacted with a hydrotreating catalyst, preferably a heterogeneous hydrotreating catalyst, in the presence of hydrogen in at least one dedicated hydrotreating unit (HP2) to obtain a product stream (80) containing ethylbenzene. The heterogeneous hydrotreating catalyst in (HP3) can be the same as the heterogeneous catalyst used for the ACP hydrogenation step in the hydrotreating unit (HP). According to one embodiment, the dedicated hydrogenation unit (HP2) comprises one slurry hydrogenation reactor (HP2); or it can comprise two or more slurry hydrogenation reactors (HP2 1 HP2 2 , ...HP2 n) (stirred, thoroughly mixed, with powdered catalyst), these reactors can use the same catalysts as the acetophenone hydrogenation process, described below.

[0200] The hydrogenation unit is supplied with a catalyst (70) and hydrogen (60). A gas stream (85) containing unreacted hydrogen and a hydrogenation product slurry containing the catalyst are separated from the hydrogenation unit and separated from the hydrotreated liquid (80) by, for example, filtration (F2). A portion of the separated catalyst is recycled to the hydrogenation unit (75) and another portion is removed (90).

[0201] A person skilled in the art knows how to choose a suitable catalyst and the conditions for carrying out this hydrotreatment step. As catalyst feed (70) it is possible to use "spent" catalyst from the ACP hydrogenation process (265), and as hydrogen feed (60) it is possible to use the waste gas from the ACP hydrogenation unit (260). The product stream (80) can either be fed to the ACP hydrogenation unit (HP1) or mixed with the hydrogenated liquid product obtained from the ACP hydrogenation unit (270). See Figure 2A .

[0202] c.1B. Hydroprocessing unit for ACP hydrogenation step (HP1) - see Figure 3A and 3B .

[0203] According to this embodiment, in the hydroprocessing unit (HP1), the first fractionated side stream (30) is contacted with a hydroprocessing catalyst, preferably a heterogeneous hydroprocessing catalyst, in the presence of hydrogen to carry out an ACP hydrogenation step. According to one embodiment, the hydrogenation unit (HP1) comprises one slurry hydrogenation reactor (HP1); or may comprise two or more slurry hydrogenation reactors (HP1) connected in series or in parallel. 1 、HP1 2 ...HP1 n ) (stirred, thoroughly mixed, with powdered catalyst). The first fractionated side stream (30) may be fed to one or more such hydrogenation reactors.

[0204] Therefore, according to certain embodiments, the hydrogenation unit (HP1) comprises two or more slurry hydrogenation reactors (HP1) connected in series. 1 、HP1 2 …HP1 n ); wherein the first fractionation side stream (30) is at different HP1 n The first fractionation side stream (30) is fed to the first hydroprocessing reactor (HP1 1) produces a product stream containing ethylbenzene, which is fed to the next subsequent reactor, and then the process is repeated for n reactors until the nth hydroprocessing reactor (HP1 n ) to obtain a product stream (270) containing ethylbenzene. According to certain embodiments, the first fractionation side stream (30) is subjected to different HP1 n The distribution between the reactors is carried out to adjust the styrene monomer concentration in the feed stream to each reactor to be less than 15 wt %, preferably less than 10 wt %, based on the total feed stream to each reactor.

[0205] like Figure 3A and 3B As shown, the feed entering the hydroprocessing unit (HP1) includes hydrogen (240), a slurry containing a catalyst (250), and a mixture of the first fractionation side stream (30), a distilled product stream (220), and a stream containing ethylbenzene (170). The products coming out of the hydrogenation unit are a gas stream containing unreacted hydrogen (260) and a slurry of hydrogenated products containing the catalyst, which is separated from the hydroprocessing liquid (270) by, for example, filtration (F1). A portion of the separated catalyst is recycled to the hydrogenation unit (250), and another portion is removed (265).

[0206] c.2) introducing the first fractionated side stream (30) obtained in b.1) or b.2) into a distillation column (D5) - see Figure 4A and 4B .

[0207] According to this embodiment of the invention, the first fractionation side stream (30) is fed together with the heavy bottom product streams (140) and (200) into a distillation column (D5) to obtain a distillate product stream (220); the distillate product stream (220) is fed into a hydroprocessing unit (HP) of step c.1), preferably into a hydroprocessing unit (HP1) of step c.1B), where it is contacted with a hydroprocessing catalyst in the presence of hydrogen to obtain a product stream (270) containing ethylbenzene - see Figure 4A and 4B .

[0208] According to the embodiments of step c.1), also according to c.2), optionally in combination with one or more features of the specific embodiments defined herein, the hydrogenation is carried out in a series of slurry reactors (e.g., in two or more reactors connected in series), using, for example, a copper catalyst or a copper chromite catalyst. Specific examples of hydrogenation catalysts are well known in the art, such as Cu 0542P commercially available from BASF, which comprises 58 wt.% CuO, 12 wt.% MnO 2 , d50 5 microns, Scott ABD 0.4g / ml and surface area 90m2 / g; or E-108P from BASF, which is a copper chromite catalyst containing 35 wt% Cu, 30 wt% Cr, 9 wt% Ba, filled with ABD 1.0 g / cc, and a surface area of ​​40 m 2 / g, d50 15 microns.

[0209] According to another embodiment, optionally in combination with one or more features of specific embodiments defined herein, the process is carried out according to step c.1B), wherein at least two hydroprocessing reactors connected in series are used, and wherein at least a portion of the first fractionated side stream is hydroprocessed in the first hydroprocessing reactor (HP1 1 ) and the nth hydroprocessing reactor (HP1 n ) are distributed among them.

[0210] Different hydrogenation reactors (HP1 1 , HP1 2 , ..., HP1 n ) can be the same or different, as described above.

[0211] The specific conditions for operating a hydroprocessing unit (HP) can be routinely applied by a person skilled in the art based on technical information in the common general knowledge.

[0212] According to specific embodiments, optionally in combination with one or more features of specific embodiments defined herein, in step c), the gas purge is operated to maintain a hydrogen partial pressure of 15 to 30 bara and a temperature of 150 to 210°C.

[0213] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the hydrogenation of step c) is carried out in the same hydroprocessing unit (HP) used in the PO / SM process, so that step c) is carried out in the presence of an acetophenone stream, wherein the conversion of acetophenone is 80% to 95%, the selectivity to 1-phenylethanol is 80% to 90%, and the rest is ethylbenzene.

[0214] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, in the hydrogenation step c), 95% to 100% of the styrene entering the reaction process is converted into ethylbenzene, and other C9 vinyl aromatic compounds (such as α-methylstyrene) are also saturated. The effluent from the last reactor is degassed, the catalyst is filtered and recovered, and finally recycled to the ethylbenzene purification unit (270). In order to maintain the reaction conversion rate, catalyst cleaning and replenishment are required.

[0215] According to a preferred embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the method is carried out according to step c.2), wherein the first fractionation side stream (30) is fed to a distillation tower (D5) to obtain a distilled product stream (220); the distilled product stream (220) is then fed to a hydroprocessing unit (HP1) of step c.1B), wherein it is contacted with a heterogeneous hydroprocessing catalyst in the presence of hydrogen to obtain an ethylbenzene product stream (270).

[0216] Those skilled in the art can routinely apply the specific conditions according to methods known in the art based on technical information in common knowledge.

[0217] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, after performing option b.1) or b.2) and before step c), the method further comprises alkali washing or water washing the first fractionation side stream (30). By alkali washing or water washing the first fractionation side stream (30), a reduction of heteroatom-containing compounds present in the first fractionation side stream (30) is achieved. The presence of these heteroatom-containing compounds may lead to the formation of salts and acids, which may need to be removed in the process because they may cause catalyst poisoning, etc.

[0218] Step d) - Ethylbenzene Recovery

[0219] In step d), the ethylbenzene-containing product stream (80, 270) obtained in step c) is fed to an ethylbenzene distillation column (D1), thereby recovering a distilled ethylbenzene stream (110) from the top of the column and a stream (120) containing α-methylbenzyl alcohol from the bottom. The stream (120) containing α-methylbenzyl alcohol also contains C8+ impurities such as xylene, cumene, ethyltoluene and other impurities from the starting material (i.e., a hydrocarbon liquid stream produced by pyrolysis of waste plastics) and from a fresh ethylbenzene stream (100).

[0220] Step e) - Ethylbenzene oxidation

[0221] Furthermore, in step e), according to the well-known PO / SM process (see Figure 6 ), the ethylbenzene product stream (110) (optionally together with fresh ethylbenzene (100)) is introduced into an ethylbenzene oxidation unit to produce an ethylbenzene hydroperoxide stream (330) by liquid phase oxidation using air, oxygen-enriched air or oxygen as an oxidant.

[0222] For a person skilled in the art, the specific operating conditions of an ethylbenzene oxidation unit, in which ethylbenzene is oxidized to ethylbenzene hydroperoxide, can be routinely applied based on technical information in common common sense. For example, see Propylene OxidePERP 2012-7, pages 19-20.

[0223] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the oxidation of the ethylbenzene product stream (110) to ethylbenzene hydroperoxide is carried out by a non-catalytic reaction at a temperature in the range of 120 to 180° C. and a pressure in the range of 1 to 15 bara. Adding a basic compound (e.g., magnesium carbonate, NaOH or KOH) to neutralize the acid formed can promote the reaction and reduce the decomposition of the hydroperoxide.

[0224] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the oxidation step e) can be carried out in a series of stirred tank reactors until the ethylbenzene conversion is between 10% and 50%, preferably to about 13%. The main by-products of the reaction are 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone.

[0225] According to one embodiment, the oxidation reactor effluent may be passed through a separate stage wherein a portion of the ethylbenzene is removed for recycle, the reactor effluent is cooled, and the ethylbenzene hydroperoxide concentration of the reactor effluent is increased.

[0226] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, in oxidation step e), the ethylbenzene fed to the process may consist of different ethylbenzene-containing streams: fresh (make-up) ethylbenzene (100), recovered ethylbenzene separated downstream of the epoxidation section (110).

[0227] Generally, the standard specifications of commercial (fresh) ethylbenzene (100) according to ASTM D3193-17 are shown in Table 1.

[0228] Table 1. Commercial (fresh) ethylbenzene specifications

[0229] Components Specification unit Ethylbenzene 99.00 Weight%, min. benzene 0.1 Weight%, max. Toluene 0.4 Weight%, max. Xylene 0.4 Weight%, max. Cumene 0.03 Weight%, max. Diethylbenzene 0.003 Weight%, max. chloride 1 mg / kg, max sulfur 1 mg / kg, max

[0230] According to one embodiment, optionally in combination with one or more features of the specific embodiments defined herein, the distilled ethylbenzene stream (110) comprises an ethylbenzene content of 93 wt% to 99.5 wt%, a benzene content of 0.001 wt% to 0.1 wt% and an aromatic compound C8+ (xylene, isopropylbenzene, ethyltoluene, etc.) content of 0.1 wt% to 5 wt%.

[0231] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the distilled ethylbenzene stream (110) comprises:

[0232] - 93 to 99% by weight of ethylbenzene, preferably 95 to 99% by weight;

[0233] - 0.001 to 0.1% by weight of benzene, preferably 0.01 to 0.05% by weight;

[0234] - 0.01 to 1% by weight of toluene, preferably 0.1 to 0.5% by weight;

[0235] - 0.01 to 1% by weight of o-xylene, preferably 0.1 to 0.5% by weight;

[0236] - 0.01 to 3% by weight of meta-xylene, preferably 0.1 to 1.5% by weight;

[0237] - 0.01 to 3% by weight of p-xylene, preferably 0.1 to 1.5% by weight;

[0238] - 0.01 to 1% by weight of cumene, preferably 0.1 to 0.5% by weight;

[0239] - 1 ppm to 1000 ppm by weight of diethylbenzene, preferably 10 ppm to 100 ppm by weight;

[0240] - 0.0001% to 0.1% by weight of n-propylbenzene, preferably 0.001% to 0.01% by weight;

[0241] - 0.001% to 0.1% by weight of one or more compounds selected from the group consisting of mixtures of (C3-C8)alkanes, (C2-C8)alkenes, (C5-C8)cycloalkanes and (C5-C8)cycloalkenes, preferably 0.01% to 0.06% by weight;

[0242] - 0.01 ppmw to 50 ppmw of heteroatom-containing compounds, preferably 0.1 ppmw to 5 ppmw;

[0243] - 0.1 ppmw to 250 ppmw of water, preferably 0.1 ppmw to 100 ppmw.

[0244] The reaction proceeds via free radicals and in order to maintain product selectivity, the amount of impurities in the feed needs to be limited.

[0245] The heat of reaction can be removed by evaporating liquid into the reaction gas outlet stream. The evaporated liquid (ethylbenzene) is condensed and recycled to the reactor. The non-condensed product (excess oxygen and nitrogen used) stream (340) in the reaction tail gas is discharged to the atmosphere after removing trace organic matter (ethylbenzene and other substances).

[0246] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the oxidation step e) may be performed using air, oxygen-enriched air or pure oxygen.

[0247] Step f) - Propylene epoxidation

[0248] The ethylbenzene hydroperoxide obtained in e) is reacted with propylene in the presence of a catalyst in an epoxidation unit to produce crude propylene oxide (300). The epoxidation step can be carried out in a fixed bed catalytic reactor device or in a homogeneous catalytic liquid phase reactor. The specific conditions, pressure and temperature of these steps can be adjusted by a person skilled in the art according to applicable common sense, for example, see Propylene Oxide, PERP 2012-7, page 21.

[0249] In the step of epoxidizing propylene to propylene oxide using ethylbenzene hydroperoxide as an epoxidizing agent, those skilled in the art can routinely apply specific conditions according to methods known in the art based on technical information in common knowledge.

[0250] Thus, according to a particular embodiment, the epoxidation step can be carried out in the liquid phase at a temperature ranging from 80 to 150° C., preferably 115° C., at a pressure of 30 to 80 bara, preferably 40 bara, catalyzed by, for example, a homogeneous molybdenum organometallic catalyst or a heterogeneous titanium dioxide-based catalyst, and using excess propylene to increase product selectivity. The conversion of ethylbenzene hydroperoxide is about 99%.

[0251] Excess propylene is distilled from the crude epoxidation product in a series of depropanizers operating at above atmospheric pressure. The recovered propylene can be sent to the reaction stage and, if necessary, cleaned of accumulated impurities. The bottom product of the depropanizer contains ethylbenzene (EB), 1-phenylethanol (MBA, α-methylbenzyl alcohol), acetophenone (ACP), propylene oxide, heavy reaction products and light reaction products. It can also contain unconverted ethylbenzene hydroperoxide, acidic products and molybdenum catalyst for the homogeneous epoxidation process, which can be removed from the process by a liquid-liquid extraction process using an alkaline aqueous solution. Other products like phenols and aldehydes are also partially or completely removed in the same process.

[0252] According to another embodiment, optionally in combination with one or more features of the specific embodiments defined herein, propylene is epoxidized to propylene oxide using ethylbenzene hydroperoxide as epoxidant, which is carried out in a fixed bed apparatus, wherein the specific conditions can be carried out according to methods known in the art, for example, it can be carried out in a reaction sequence consisting of a plurality of adiabatic fixed bed reactors with interstage cooling, over a titanium dioxide-silicon dioxide heterogeneous catalyst, in a temperature range of 50 to 130° C. and a pressure range of 60 to 90 bar.

[0253] Based on technical information from common general knowledge, the person skilled in the art knows how to adjust the general conditions of the epoxidation step, such as the propylene:ethylbenzene hydroperoxide ratio, residence time, catalyst concentration, number and arrangement of reactors, and other reaction parameters, whether for a liquid phase or fixed bed reaction process.

[0254] The crude propylene oxide (300) obtained in step f) can be introduced into a series of propylene oxide columns for separating propylene oxide from other products. Thus, the crude propylene oxide is refined in a series of columns, which can be selected from conventional distillation, extractive distillation or a combination of both, to remove lighter components (aldehydes, such as acetaldehyde and propionaldehyde) and heavier hydrocarbon components (benzene, toluene, propylene glycol, C4+ hydrocarbons) and alcohols (methanol, ethanol, 1,2-propylene glycol, n-propanol).

[0255] The bottom product of the crude propylene oxide column (310) is introduced into the first ethylbenzene distillation column (D1) of step d) as described above. In the first distillation column ethylbenzene distillation column (D1), the bottom product from the propylene oxide column (310) and the product stream (80, 270) containing ethylbenzene are introduced, and the distilled ethylbenzene stream (110) is recovered from the remaining components at the top of the column. The distilled ethylbenzene stream (110) is sent to the upstream of the ethylbenzene oxidation unit of step e). The distilled ethylbenzene stream (110) can be optionally washed with alkali and water to reduce the content of acid, alcohol and other water-soluble impurities (mainly nitrogen-containing compounds).

[0256] According to another embodiment, optionally in combination with one or more features of specific embodiments defined herein, the bottom product from the crude propylene oxide column (310) comprises:

[0257] 0.05 to 0.5 wt % benzaldehyde;

[0258] 0.05 wt % to 2 wt % mixed xylenes;

[0259] 0.05 to 1 wt % of cumene;

[0260] 0.001 wt % to 0.1 wt % of n-propylbenzene;

[0261] 0.01 to 0.5 wt % toluene;

[0262] 0.001 wt % to 0.1 wt % benzene;

[0263] 1 to 10 wt % acetophenone;

[0264] 25 to 40% by weight of 1-phenylethanol;

[0265] 0.1 to 1.5 wt. % of 2-phenylethanol;

[0266] 0.1 wt % to 5 wt % of other low vapor pressure products produced in the oxidation and epoxidation reactions or introduced into the process with the first fractionated side stream (30);

[0267] The balance was ethylbenzene to make 100% by weight.

[0268] Step g) - MBA distillation

[0269] According to one embodiment of the process described herein, the bottom product obtained in the ethylbenzene distillation column (D1), i.e., the stream (120) containing α-methylbenzyl alcohol, is introduced into a second distillation column (D2) to obtain three fractions: a product stream top distillate (130) containing xylene, a side stream (150) rich in α-methylbenzyl alcohol, and a bottom stream (140) containing α-methylbenzyl alcohol and higher boiling point products; the heavy bottom stream (140) is sent to another distillation column (D5), preferably a deep vacuum column, to recover 1-phenylethanol (MBA, α-methylbenzyl alcohol) (210) - see Figure 5A .

[0270] Alternatively, in another embodiment, the stream (120) containing α-methylbenzyl alcohol is introduced into a second distillation column (D2), a product stream top distillate (130) containing xylene is separated, and a bottom stream is introduced into an additional distillation column (D2'), thereby obtaining an α-methylbenzyl alcohol-rich top stream (150) and a heavy bottom stream (140) containing α-methylbenzyl alcohol and higher boiling point products; the heavy bottom stream (140) is sent to another distillation column (D5), preferably a deep vacuum column, to recover 1-phenylethanol (MBA, α-methylbenzyl alcohol) (210) - see Figure 5B .

[0271] The xylene-containing product stream (130) comprises xylenes, benzaldehyde, cumene, n-propylbenzene and other aromatic C9 / C10 compounds.

[0272] According to one embodiment, the overhead product stream (130) containing xylenes mainly contains benzaldehyde and propylene glycol, as well as small amounts of 1-phenylethanol, acetophenone, ethylbenzene (not separated in the previous stage), and certain aromatics that may enter the process with fresh ethylbenzene (100) and / or come from pyrolysis oil, such as: xylenes, isopropylbenzene, n-propylbenzene and diethylbenzene; the second fraction as a side product stream (150) contains a mixture of 75% to 85% by weight of 1-phenylethanol, 5% to 15% by weight of acetophenone and small amounts of other components; the bottom product (140) contains 1-phenylethanol (MBA, α-methylbenzyl alcohol) and higher boiling products.

[0273] The xylene-containing product stream (130) may be purged from the system operating at a distillate / feed mass ratio of 0.001 to 0.015, preferably at a distillate / feed mass ratio of 0.005.

[0274] For a person skilled in the art, the specific conditions for operating a distillation column and its technical features can be routinely applied based on technical information in the common knowledge in the field.

[0275] Step h) - Dehydration of MBA

[0276] In the process of the present invention, the side stream (150) rich in α-methylbenzyl alcohol is fed to a dehydration unit (DH1) containing a catalyst to obtain crude styrene monomer (160) and water (165) which can be phase-separated; and a heavy residue (155) containing styrene oligomers is obtained from the bottom of the dehydration unit (DH1).

[0277] In step h), the catalyst used in the dehydration unit (DH1) can be a homogeneous catalyst, such as sulfuric acid, p-toluenesulfonic acid, and methanesulfonic acid; or a heterogeneous catalyst, such as titanium oxide, silica gel, aluminum oxide, and 1-methylimidazole hydrogen sulfate.

[0278] According to a specific embodiment, the dehydration reaction is a homogeneous acid-catalyzed dehydration reaction, which occurs in the liquid phase at a temperature range of 150 to 250° C., preferably 200° C. and a pressure range of 100 to 600 mmHg, preferably 220 mmHg; and wherein styrene, water, unreacted 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone are flashed off.

[0279] In certain embodiments, the steam is cooled and the water is phase separated.

[0280] Side reactions of the process are the formation of ethylbenzene and the formation of heavy components (styrene dimers, trimers and oligomers and 1-phenylethanol ether). A small purge of the dehydrator liquid phase can control the accumulation of heavy fractions.

[0281] According to one embodiment, the method further comprises converting the heavy residue (155) containing styrene oligomers obtained in the dehydration unit (DH1) in a pyrolysis unit into a recycled hydrocarbon liquid stream (recycled pyrolysis oil stream) (10'), which can be reintroduced into the first fractionation unit (T1) or the distillation column (D5).

[0282] Step i) - Styrene purification

[0283] The styrene purification section consists of two distillation columns (D3 and D4). The first column (D3) is used to remove light components (170) from the crude styrene, which is then sent to the hydroprocessing unit (HP). The styrene product is obtained from the top of the second column (D4), and the bottom product (200) from the second column (D4) is sent to the distillation column (D5).

[0284] Thus, according to one embodiment, the crude styrene (160) is fed to a distillation column (D3) in which an ethylbenzene-containing stream (170) comprising ethylbenzene (preferably 1 to 10 wt.-%, more preferably 2 to 6 wt.-%, more preferably about 4 wt.-% in styrene) is separated from the top to meet the styrene product quality specifications. This ethylbenzene-containing stream (170) is sent to a hydroprocessing unit (HP). The bottom product (180) obtained from (D3) is sent to a styrene product column (D4) and pure (>99.8 wt.-%) styrene monomer is obtained at the top (190) and separated from unconverted 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone (ACP) obtained as bottom product (200). The bottom product (200) containing MBA / ACP is sent to a distillation column (D5).

[0285] Step j) - Acetophenone recovery

[0286] According to one embodiment, optionally in combination with one or more features of specific embodiments defined herein, the "heavy bottoms" product streams (140) and (200) are fed to a distillation unit (D5).

[0287] According to one embodiment, the distillation unit (D5) may comprise one distillation column (D5) or a series of distillation columns (D5n) in order to recover in depth the valuable components carried over from those streams from the previous separation operations: acetophenone, 1-phenylethanol and styrene. The distilled product stream (220) is sent together with the styrene / ethylbenzene stream (170) to the hydroprocessing unit (HP).

[0288] For a general schematic diagram of the PO / SM process, see Figure 6 .

[0289] The distillation column (D5) may be the same as or different from the distillation column (D5) of steps b3) and c.2), and the hydroprocessing unit (HP) may be the same as or different from the hydroprocessing unit (HP) of step d).

[0290] Therefore, according to certain embodiments, the distillation tower (D5) of step j) is the same as the distillation tower of step b.3), wherein the hydrocarbon liquid stream (10) produced by pyrolysis of waste plastics is distilled together with the heavy bottom product streams (140) and (200) to obtain a distilled product stream (220), which is then sent to the hydroprocessing unit (HP) of step c.1). Figure 1C .

[0291] According to another embodiment, the distillation column (D5) of step j) is identical to the distillation column of step c.2), wherein the first fractionated side stream (30) obtained according to b.1) or b.2) is distilled together with the heavy bottom product streams (140) and (200) to obtain a distilled product stream (220), which is then fed to the hydroprocessing unit (HP) of step c.1). Figure 4A and 4B .

[0292] Throughout the specification and claims, the word "comprise" and its variations are not intended to exclude other technical features, additives, components or steps. In addition, the word "comprise" covers the case of "consisting of...". The additional objects, advantages and features of the present invention will be clear to those skilled in the art after reading the specification, or they can understand the additional objects, advantages and features of the present invention through the practice of the present invention. The following examples and drawings are provided in an illustrative manner, and they are not intended to limit the present invention. The reference numerals associated with the drawings and placed in brackets in the claims are only used to try to increase the understandability of the claims and should not be interpreted as limiting the scope of the claims. In addition, the present invention covers all possible combinations of specific and preferred embodiments described herein.

[0293] Example

[0294] 1. Hydrocarbon liquid stream

[0295] In the following examples, the hydrocarbon liquid stream (pyrolysis oil 1) is an oil having at least 50% SM obtained by pyrolysis of polystyrene (see US10301235, WO2021230312 and WO2021053074, which has the composition type described below and is not further purified). The composition type of pyrolysis oil 1 is shown in Table 2.

[0296] Table 2. Composition of polystyrene pyrolysis oil

[0297] Components Polystyrene pyrolysis oil content weight % Styrene Monomer (SM) 65.2 Ethylbenzene (EB) 2.7 Phenylacetylene 0.1 Cumene 0.3 α-Methylstyrene(AMS) 5.5 Toluene 7.0 benzene 2.0 <![CDATA[C8 aromatic compound (a) > 1.0 <![CDATA[C9 aromatic compound (b) > 1.9 <![CDATA[C 3 -C 8 Fraction (c) ]]> 0.7 <![CDATA[C10 aromatic compound (d) > 0.8 <![CDATA[Heavy oil fraction (e) > 12.19 Heteroatom compounds 0.41 water 0.2

[0298] (a) mixtures including o-xylene, m-xylene, p-xylene, etc.;

[0299] (b) mixtures including propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene, methylstyrene, etc.;

[0300] (c) C3-C8 fraction refers to a fraction comprising one or more compounds selected from the group consisting of (C3-C8)alkanes, (C3-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0301] (d) mixtures comprising divinylbenzene and ethylstyrene;

[0302] (e) A mixture including naphthalene, bibenzyl, dimer, trimer and stilbene.

[0303] For methods of preparing hydrocarbon liquid streams by pyrolysis of waste plastics having a composition type as described above, see US10301235, WO2021230312 and WO2021053074.

[0304] 2. Fractionation unit

[0305] Two different fractionation configurations were used:

[0306] Option (b.1): introducing the hydrocarbon liquid stream into a first fractionation unit (T1) to separate a C7 stream top distillate (40), a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a product side stream containing alpha-methylstyrene (50); see Figure 1A ;as well as

[0307] Option (b.2): introducing the hydrocarbon liquid stream into a first fractionation unit (T1), separating a C7 stream top fraction (40) and a side stream introduced into a second fractionation unit (T1'), said side stream being introduced into the second fractionation unit (T1') to obtain a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a side stream containing an alpha-methylstyrene product (50); see Figure 1B .

[0308] The first fractionated side stream (30) thus obtained comprises the composition disclosed in Table 3.

[0309] Table 3. First fractionation side stream (30)

[0310]

[0311] (a) mixtures including o-xylene, m-xylene, p-xylene, etc.;

[0312] (b) mixtures including propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene, methylstyrene, etc.;

[0313] (c) C3-C8 fraction refers to a fraction comprising one or more compounds selected from the group consisting of (C3-C8)alkanes, (C3-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0314] (d) mixtures comprising divinylbenzene and ethylstyrene;

[0315] (e) A mixture including naphthalene, bibenzyl, dimer, trimer and stilbene.

[0316] According to method (b.1), the pyrolysis oil (10) as described above is introduced into a distillation column, which is provided with a reboiler at the bottom and a partial condenser (liquid / vapor) at the top. The column is operated under vacuum. The head condenser is operated with cooling water and the vapor temperature can reach up to 50°C. The uncondensed vapor is sent to a refrigeration cooler, where the vapor is partially condensed at low temperature by a cooling liquid (e.g., a subcooled ethylene glycol aqueous solution). The condensed hydrocarbons are combined with the column distillate to form a C7 fraction overhead distillate (40).

[0317] Therefore, the tower is operated with partial reflux to separate benzene, toluene and light hydrocarbons (40) from the aromatic C8 side cut (30) rich in SM and EB by distillation at the top of the tower. The pyrolysis oil (10) is fed below the side extraction section of the C8 side cut (30).

[0318] At the bottom of the column, a stream rich in AMS (50) is obtained as side liquor extract.

[0319] At the bottom of the column, distillation vapors are generated by means of a reboiler, which may be of a type known in the art, and a heavy stream, the fraction C9+ (20), is separated.

[0320] This embodiment is obtained by computer simulation using the UNIFAC characterization method (using Aspen Plus modeling software). The following are the process conditions used:

[0321] - 30 theoretical stages. Feed to stage 19 (upper) and side draw of the C8 fraction from stage 12 and the AMS fraction from stage 27 (1st stage = condenser; 30th stage = boiler or reboiler).

[0322] - Reflux ratio: 116

[0323] -C8 fraction to feed mass ratio: 0.716

[0324] -AMS fraction to feed mass ratio: 0.045

[0325] -Residue to feed mass ratio: 0.137

[0326] - Condenser: Partial vapor to liquid. Temperature 50°C.

[0327] -Condenser steam cooler temperature: 5℃

[0328] - Pressure characteristics: stage 1 - 155 mmHg; stage 2 - 175 mmHg; pressure drop for the remaining columns - 20 mmHg.

[0329] The process simulation was carried out under the above conditions, and the conditions and key component compositions of the main pyrolysis oil fractionation stream were obtained as follows (Table 4).

[0330] Table 4. Polystyrene pyrolysis oil fractionation results (weight %) (method b.1)

[0331]

[0332] (a) mixtures including o-xylene, m-xylene, p-xylene, etc.;

[0333] (b) mixtures including propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene, methylstyrene, etc.;

[0334] (b) C3-C8 fraction refers to a fraction comprising one or more compounds selected from the group consisting of (C3-C8)alkanes, (C3-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0335] (d) mixtures comprising divinylbenzene and ethylstyrene;

[0336] (e) A mixture including naphthalene, bibenzyl, dimer, trimer and stilbene.

[0337] It was observed in the SM product (30) that C8 and isopropylbenzene were not separated, but benzene, toluene and heavy components as well as part of AMS and n-propylbenzene were removed, with an SM recovery of 99% (EB recovery of 89%), and a stream rich in SM+EB (about 94 wt.% and up to 2.5 wt.% AMS) was obtained.

[0338] According to method (b.2), the pyrolysis oil (10) as described above is introduced into a first distillation column, which is provided with a reboiler at the bottom and a partial condenser (liquid / vapor) at the top. The column is operated under vacuum. The head condenser is operated with cooling water and the vapor temperature can reach up to 40°C. The uncondensed vapor is sent to a refrigeration cooler, where the vapor is partially condensed at low temperature by a cooling liquid (e.g., subcooled glycol water). The condensed hydrocarbons are combined with the column distillate to form a C7 fraction overhead distillate (40).

[0339] Therefore, the tower is operated with partial reflux, and benzene, toluene and light hydrocarbons (40) are separated by distillation at the top of the tower.

[0340] At the bottom of the column, distillation vapors are produced by a reboiler, which may be of a type known in the art, and the bottom stream thus obtained is fed to a second distillation column having a reboiler at the bottom and a total condenser at the top. The column works under vacuum.

[0341] Therefore, the column is operated with partial reflux and the SM-rich overhead stream (30) is separated by distillation.

[0342] At the bottom of the column, an AMS-rich stream (50) is obtained by lateral liquid withdrawal.

[0343] At the bottom of the column, distillation vapors are generated by means of a reboiler, which may be of a type known in the art, and a heavy stream, the fraction C9+ (20), is separated.

[0344] This embodiment is obtained by computer simulation using the UNIFAC characterization method (using Aspen Plus modeling software). The following are the process conditions used:

[0345] First distillation column:

[0346] - 15 theoretical stages. Feed to stage 8 (above) (1st stage = condenser; 15th stage = boiler or reboiler).

[0347] - Reflux ratio: 19.5

[0348] - Distillate to feed mass ratio: 0.1

[0349] - Condenser: Partial vapor to liquid. Temperature 40°C.

[0350] -Condenser steam cooler temperature: 5℃

[0351] - Pressure characteristics: 1st stage - 175 mmHg; 2nd stage - 180 mmHg; pressure drop of the remaining towers - 30 mmHg.

[0352] Second distillation column:

[0353] - 20 theoretical stages. Feed to stage 10 (upper) and AMS fraction withdrawn laterally from stage 18 (1st stage = condenser; 20th stage = boiler or reboiler).

[0354] - Reflux ratio: 0.985

[0355] -AMS fraction to feed mass ratio: 0.045

[0356] - Distillate to feed mass ratio: 0.795

[0357] -Condenser: All

[0358] - Pressure characteristics: stage 1 - 155 mmHg; stage 2 - 160 mmHg; pressure drop for the remaining columns - 30 mmHg.

[0359] The process simulation was carried out under the above conditions, and the conditions and key component compositions of the main pyrolysis oil fraction flow were obtained as follows (Table 5).

[0360] Table 5. Polystyrene pyrolysis oil fractionation results (weight %) (method b.2)

[0361]

[0362] (a) mixtures including o-xylene, m-xylene, p-xylene, etc.;

[0363] (b) mixtures including propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene, methylstyrene, etc.;

[0364] (b) C3-C8 fraction refers to a fraction comprising one or more compounds selected from the group consisting of (C3-C8)alkanes, (C3-C8)olefins, (C5-C8)cycloalkanes and (C5-C8)cycloolefins;

[0365] (d) mixtures comprising divinylbenzene and ethylstyrene;

[0366] (e) A mixture including naphthalene, bibenzyl, dimer, trimer and stilbene.

[0367] For compounds containing heteroatoms, process simulation is not feasible. An intermittent distillation experiment was conducted using a 15-theoretical-stage distillation tower, a reflux ratio of 15, and a pressure of 100 mmHg. The results are shown in Table 6.

[0368] Table 6. Fractionation of polystyrene pyrolysis oil. Heteroatom distribution (t)

[0369]

[0370] 3. Effect of introducing hydrocarbon liquid stream (10) into POSM process

[0371] Comparative Example 1. POSM process without introducing (10)

[0372] Figure 6 Process flow diagrams for a propylene oxide / styrene monomer (PO / SM) process for producing styrene via an ethylbenzene hydroperoxide intermediate are shown. These flow diagrams do not show the ethylbenzene oxidation and ethylbenzene hydroperoxide epoxidation portions of the process, nor the propylene oxide purification portion of the process.

[0373] The first step of the process is the non-catalytic air oxidation of ethylbenzene to ethylbenzene hydroperoxide at about 150°C and a pressure of 2.8 bara. The reaction is carried out in a series of stirred tank reactors with an ethylbenzene conversion of about 13%. The selectivity for ethylbenzene hydroperoxide is 80%. The main by-products of the reaction are 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone (ACP). Minor by-products are aldehydes, acids and phenols obtained from the secondary oxidation reaction. The ethylbenzene feed to the process consists of two streams, fresh (make-up) ethylbenzene (100) and recovered ethylbenzene (110) separated downstream of the epoxidation section.

[0374] Table 7 shows the ethylbenzene make-up streams considered (same for all examples disclosed herein):

[0375] Table 7. Supplemental ethylbenzene (100)

[0376] Compound Composition (weight %) Ethylbenzene 99.9121 benzene 0.0619 Toluene 0.0099 <![CDATA[C8 aromatic compound a > 0.0054 Cumene 0.0046 <![CDATA[C9 aromatic compound b > 0.0038 <![CDATA[C10 aromatic compound c > 0.0023

[0377] (a) A mixture comprising o-xylene, m-xylene and p-xylene;

[0378] (b) mainly n-propylbenzene;

[0379] (c) Mainly diethylbenzene.

[0380] The heat of reaction is removed by evaporating liquid into the reaction gas outlet stream. The evaporated liquid (ethylbenzene) is condensed and the waste gas (excess oxygen and nitrogen used) is freed of trace organic matter (ethylbenzene, etc.) and discharged to the atmosphere.

[0381] The next step of the process is the epoxidation of propylene to propylene oxide using ethylbenzene hydroperoxide as an epoxidant in a concentration of up to 35 wt %, also producing 1-phenylethanol. The reaction is carried out in the liquid phase at 115°C and 40 bara, catalyzed by a molybdenum organometallic catalyst, and using excess propylene to increase product selectivity. The conversion of ethylbenzene hydroperoxide is about 99%. Excess propylene is distilled from the crude epoxidation product in a series of depropanizers operating above atmospheric pressure. The recovered propylene is sent to the reaction stage, where it is cleaned of accumulated impurities and fresh propylene is added (320) if necessary. The bottom product of the depropanizer contains ethylbenzene (EB), 1-phenylethanol (MBA, α-methylbenzyl alcohol), acetophenone (ACP), propylene oxide, heavy reaction products and light reaction products. It also contains unconverted ethylbenzene hydroperoxide, acidic products and molybdenum catalyst, which are removed from the process by a liquid-liquid extraction process using an alkaline aqueous solution. Other products such as phenols and aldehydes are also partially or completely removed in the same process.

[0382] The latter product stream is sent to a crude propylene oxide column which is used to separate crude propylene oxide (300) from other products. The crude propylene oxide is refined in a series of columns to remove lighter components (aldehydes such as acetaldehyde and propionaldehyde) and heavier hydrocarbon components (benzene, toluene, propylene glycol, C4+ hydrocarbons) and alcohols (methanol, ethanol, 1,2-propylene glycol, n-propanol).

[0383] The bottom product of the crude propylene oxide column is sent to two successive columns (D1 and D2). In the first distillation column (D1), ethylbenzene is recovered from the remaining components at the top (110) and sent to the upstream ethylbenzene oxidation section. The bottom product is sent to a second distillation column (D2) where three fractions are obtained: an overhead product (130) containing mainly benzaldehyde and propylene glycol as well as small amounts of 1-phenylethanol, acetophenone, ethylbenzene (not separated in the previous stage) and certain aromatic compounds which may have entered the process together with the fresh ethylbenzene (100), such as xylene, isopropylbenzene, n-propylbenzene and diethylbenzene; a second fraction as a side product stream (150) consisting of a mixture of 80% by weight of 1-phenylethanol, 10% by weight of acetophenone and small amounts of other components; and finally, a bottom product (140) containing part of 1-phenylethanol (MBA, α-methylbenzyl alcohol) and higher boiling point products, which is sent to a deep vacuum column (D5) to recover 1-phenylethanol.

[0384] Table 8. Formation of oxidation and epoxidation by-products.

[0385] product t / t SM product* Benzaldehyde 0.0020 Acetophenone 0.1617 1-Phenylethanol 1.0968 Benzyl alcohol 0.0152 2-Phenylethanol 0.0127 1-Phenyl-2-propanol 0.0254 1,1'-Oxybis(ethane-1,1-diyl)dibenzene and isomers 0.0254 Oxidation and epoxidation of heavy fractions 0.0017

[0386] * "t / t SM product" refers to the metric tons of product produced per metric ton of styrene monomer stream (190)

[0387] The 1-phenylethanol (MBA, α-methylbenzyl alcohol) / acetophenone (ACP) stream (150) is fed to a dehydration reactor. The homogeneous acid-catalyzed dehydration reaction is carried out in the liquid phase at 200°C and 220 mmHg, and styrene, water, unreacted 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone are flashed off. The steam is cooled and the water is phase separated. The side reactions of the process are the formation of ethylbenzene and the formation of heavy components (styrene dimers, trimers and oligomers and 1-phenylethanol ether). A small amount of purge of the dehydrator liquid phase controls the accumulation of heavy fractions.

[0388] The crude styrene (160) is sent to a light column (D3) where some ethylbenzene (about 4 wt. % in styrene) is separated from the top (170) to meet the styrene product quality specifications. The bottom product is fed to a styrene product column (D4) where pure (>99.8 wt. %) styrene monomer is obtained at the top (190) and separated from unconverted 1-phenylethanol (MBA, α-methylbenzyl alcohol) and acetophenone obtained as bottom product (200).

[0389] The "heavy bottoms" product streams (140) and (200) produced by the process are sent to a deep vacuum column (D5) or a series of distillation columns to recover the valuable components left over from the previous separation operations in these product streams: 1-phenylethanol, acetophenone and styrene. The distilled product stream (220) is fed to the hydrogenation reaction section together with the styrene / ethylbenzene stream (170).

[0390] Using copper oxide type catalyst, hydrogenation reaction is experimentally carried out in a liter autoclave reactor. 500 grams of liquid of the composition shown in Table 9 and 1.5 grams of catalyst Cu 0542P from BASF are loaded into the reactor. Close the reactor, purge with nitrogen and purge with pure hydrogen. Then, under stirring, the reactor contents are heated to 188 ° C. Pure hydrogen (> 99.99 volume %) is passed, and the total pressure is maintained at 24 bara, and the temperature is controlled at 188 ° C for 180 minutes. Afterwards, the reactor is cooled, and the pressure is reduced to atmospheric pressure, and the product is then discharged for analysis. Table 9 shows the main results obtained.

[0391] Table 9

[0392] Feed composition Ethylbenzene (weight %) 0.005 Styrene (wt%) 0.245 Acetophenone (weight %) 43.115 1-Phenylethanol (wt%) 20.55 α-Methylstyrene (wt%) 0 Reaction results Styrene conversion rate % 98.9 Acetophenone conversion rate % 94.3 Selectivity of 1-phenylethanol to acetophenone % 83.5

[0393] In another embodiment, hydrogenation is carried out in a series of two slurry reactors using a 0.2 wt% copper chromite type catalyst. Hydrogen (90 volume %) is fed to each reactor and a gas purge is performed to maintain the desired hydrogen partial pressure at about 24 bara. The temperature is maintained at about 190° C. The total residence time is about 2.5 hours. Table 10 shows the main results obtained.

[0394] Table 10

[0395] Feed composition Ethylbenzene (weight %) 2.03 Styrene (wt%) 1.53 Acetophenone (weight %) 51.65 1-Phenylethanol (wt%) 28.78 α-Methylstyrene (wt%) 0 Reaction results Styrene conversion rate % 98.5 Acetophenone conversion rate % 88.3 Selectivity of 1-phenylethanol to acetophenone % 90.7

[0396] Comparative Example 2. PO / SM process of introducing the fractionated styrene product stream (30) into the crude styrene distillation column (D3)

[0397] According to the above method (b1 method), 0.026 tons of polystyrene pyrolysis oil is fractionated for every ton of styrene monomer produced according to the method of Comparative Example 1. The fractionated styrene product stream (30) is sent to the crude styrene distillation (D3) and mixed with the crude styrene product of the dehydrator phase separator (see Figure 7 ). The rest of the process is the same as that of Comparative Example 1.

[0398] Comparative Example 3. PO / SM process of introducing polystyrene pyrolysis oil (10) into crude styrene distillation column (D3)

[0399] 0.026 tons of polystyrene cracking oil generated per ton of styrene monomer produced in Comparative Example 1 is sent to crude styrene distillation (D3) and mixed with the crude styrene product of the dehydrator phase separator (see Figure 8 ). The rest of the process is the same as that of Comparative Example 1.

[0400] Example 1. PO / SM process of introducing the fractionated styrene product stream (30) into the hydrogenation unit (HP) according to the present invention - Figure 3B

[0401] According to the above method (option b.1 method), 0.026 tons of polystyrene pyrolysis oil are fractionated for every ton of styrene monomer produced according to Comparative Example 1. The fractionated styrene product stream (30) is sent to the hydrogenation unit (HP) as described in method c.1B. The rest of the process is the same as Comparative Example 1.

[0402] The hydrogenation reaction was carried out in a liter autoclave reactor using a copper oxide type catalyst. 426 grams of a liquid rich in acetophenone as in Comparative Example 1, 6.8 grams of a mixture of 96% by weight styrene and 4% by weight ethylbenzene and 16.7 grams of fractionated polystyrene pyrolysis oil as described above were mixed to obtain the composition shown in Table 9, and 1.35 grams of catalyst Cu0542P from BASF was loaded into the reactor. The reactor was closed, purged with nitrogen and purged with pure hydrogen. The reactor contents were then heated to 188° C. under stirring. Pure hydrogen (>99.99% by volume) was introduced, the total pressure was maintained at 24 bara, the temperature was controlled at 188° C., and the duration was 180 minutes. Afterwards, the reactor was cooled, the pressure was reduced to atmospheric pressure, and the product was then discharged for analysis. The spent catalyst was filtered out and recycled according to the same procedure, with only 68 mg of fresh catalyst added. Table 11 shows the main results obtained.

[0403] Table 11

[0404] Feed composition Ethylbenzene weight% 0.497 Styrene weight% 3.806 Acetophenone weight% 43.226 1-Phenylethanol weight% 18.139 α-Methylstyrene weight% 0.284 Chloride ppmw 4.7 Bromideppmw 0.5 Fluoride ppmw 0.3 Nitrogen ppmw 150 Sulfur ppmw 0.3 Acidity, mgKOH / g 0.008 Results obtained with the first use of the catalyst Styrene conversion rate % 97.48 Acetophenone conversion rate % 95 α-Methylstyrene conversion 98.9 Selectivity of 1-phenylethanol to acetophenone % 83 Results obtained with the second use of the catalyst Styrene conversion rate % 96.5 Acetophenone conversion rate % 95 α-Methylstyrene conversion 83.1 Selectivity of 1-phenylethanol to acetophenone % 70

[0405] Example 2 according to the present invention: Introducing the fractionated styrene product stream (30) into the distillation unit (D5) PO / SM process - Figure 4B

[0406] According to the above method (option b.1 method), 0.026 tons of polystyrene pyrolysis oil is fractionated for every ton of styrene monomer produced according to Comparative Example 1. The fractionated styrene product stream (30) is sent to the distillation unit (D5) as described in method c.2. The rest of the process is the same as Comparative Example 1.

[0407] The following table lists the key results for all the examples above:

[0408] Table 12. Styrene Monomer Flow (190)

[0409]

[0410] (a) mixtures including o-xylene, m-xylene, p-xylene, etc.;

[0411] (b) A mixture comprising propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene, methylstyrene and the like.

[0412] Some specification values ​​for styrene monomer quality are as follows (see PERP 0304-8 Styrene-Ethylbenzene, page 39):

[0413] Styrene 99.90% by weight minimum Aldehydes (such as benzaldehyde) 50wppm maximum <![CDATA[Peroxides (such as H 2 O 2 )]]> 20wppm maximum polymer 5wppm maximum α-phenylethylene 250wppm maximum C8 / C9 Aromatics 100wppm maximum

[0414] C8 / C9 aromatics include: o-xylene, m-xylene, p-xylene, ethylbenzene, phenylacetylene, allylbenzene, n-propylbenzene, methylethylbenzene and methylstyrene.

[0415] Typical analysis of commercially available styrene (see Safe Handling and storage of Styrene Monomer de Chevron Phillips, 20-8-2009, page 8):

[0416]

[0417] The following conclusions can be drawn from the above examples:

[0418] -SM abundance. Comparative Example 2 is still within the limit, Comparative Example 3 is out of specification, while the remaining examples are above the lower specification limit, and the values ​​of Examples 1 and 2 are similar to Comparative Example 1 (reference).

[0419] -α-Methylstyrene: higher than the reference specification in Comparative Example 3, and higher than the reference example (Comparative Example 1) and Examples 1 and 2 in Comparative Example 2, wherein the α-methylstyrene content is higher than Comparative Example 1 but within the numerical range.

[0420] - C8 / C9 aromatics. All examples show values ​​above the reference specification (until Comparative Example 1, which is a reference example without oil), however, in Examples 1 and 2, although with slightly higher values, this is very similar to Comparative Example 1 (reference), and in Comparative Examples 2 and 3, these values ​​are significantly increased. It is observed that in Examples 1 and 2 (except Comparative Example 1), these values ​​are better than the typical analysis of commercial styrenes shown previously, while in Comparative Examples 2 and 3, the results are inferior, especially in terms of EB content.

[0421] -C6 / C8 aliphatic compounds are new components not present in currently commercial SM, which may affect the commercial use of styrene, and are present in the SM products in Comparative Examples 2 and 3, but not in the other cases.

[0422] As observed, in Examples 1 and 2, where the pyrolysis oil was previously hydrogenated, there was no net increase in SM production (what was achieved was "production" of EB). In Comparative Examples 2 and 3, there was an increase in production. Furthermore, in Examples 1 and 2, although a net increase in xylenes, cumene, and α-methylstyrene was observed, they all met the ASTM D2827 specification. In Comparative Examples 2 and 3, however, the products did not meet the ASTM D2827 specifications for these components.

[0423] Furthermore, a large amount of impurities were present in the SM products obtained in Comparative Examples 2 and 3.

[0424] The xylene-containing product stream (130) comprises a composition as disclosed in Table 13.

[0425] Table 13. Composition of the product stream (130) containing xylene

[0426]

[0427] *“t / t SM (190) produced” refers to the mass ratio of the xylene-containing product stream (130) to the styrene monomer product stream (190) in tonnes / tonnes **“t / t SM product” refers to the metric tons of product produced per metric ton of styrene monomer stream (190)

[0428] (a) Mixtures including o-xylene, m-xylene, p-xylene, etc.

[0429] (b) A mixture comprising n-propylbenzene and ethyltoluene

[0430] (c) Mainly diethylbenzene

[0431] (d) Mainly styrene dimer

[0432] It can be seen that in Examples 1 and 2, for the same total output, the effective cleaning amount of xylene, isopropylbenzene (cumene) and n-propylbenzene is greater than that of Comparative Example 1, proving that impurities can be effectively removed by the cleaning method described in the present invention.

[0433] In short, it is not feasible to feed pyrolysis oil in the manner of Comparative Example 2 or Comparative Example 3.

[0434] Directly feeding the polystyrene pyrolysis oil (Comparative Example 3) or the C8 fraction obtained by distilling the polystyrene pyrolysis oil (Comparative Example 2) into the styrene purification section of the PO / SM process means that EB, cumene, n-propylbenzene, AMS, xylene, etc. are directly mixed into the SM product, making it non-compliant. In addition, "new" impurities (C7-C8 aliphatic hydrocarbons, allylbenzene, ethyltoluene) are also mixed into the SM.

[0435] There are no process variables available to control the above values, except to limit their entry into the pyrolysis oil as much as possible, to limit the possibilities of using existing pyrolysis processes, or to adopt complex purification processes (which require a large number of distillation separation steps and / or a large amount of energy, which reduces or eliminates the advantages of process integration in terms of energy consumption).

[0436] According to Example 1, the net production of SM will remain unchanged, but as shown in the example, about 0.017 tEB / t SM of "virgin" EB (100) will be saved by "recycled" EB generated from pyrolysis oil, and due to the introduction of polystyrene pyrolysis oil into the process, an equal amount of SM of "recycled" origin will be generated (the quality of SM remains within specifications).

[0437] The fractionated styrene product stream (30) is fed (pre-fractionated) to the process by feeding to a distillation column (D5) according to Comparative Example 2. As a pre-fractionated feed (weight eliminated), it means an "extra" load on the distillation section of the hydrogenation unit.

[0438] References cited in the application

[0439] 1. ASTM D-2827;

[0440] 2. Ki-bumPark et al., Applied Energy 259, 2020, p. 114240;

[0441] 3. Ibrahim M. Maafa. Polymers, 2021, Vol. 13, p. 225;

[0442] 4. John Scheirs and Walter Kaminsky, "Feedstock Recycling and Pyrolysis of Waste Plastics: Converting Waste Plastics into Dieseland Other Fuels", WileyOnline Library, 2006, page 635;

[0443] 5. Jasmin Shah et al., “Conversion of waste polystyrene through catalytic degradation into valuable products”, Korean J. Chem. Eng., 2014, Vol. 31(8), pp. 1389-1398;

[0444] 6. ASTM D3193-17;

[0445] 7. ASTM D664;

[0446] 8. EPA3051a;

[0447] 9. ASTM D6052-97;

[0448] 10. ASTM D2827;

[0449] 11. US10301235;

[0450] 12. WO2021230312;

[0451] 13. WO2021053074;

[0452] 14.PERP 2012-7 Propylene Oxide, pp. 19-26;

[0453] 15.PERP0304-8 Styrene-Ethylbenzene, page 39;

[0454] 16.Safe Handling and storage of Styrene Monomer de Chevron Phillips, 20-8-2009, page 8.

Claims

1. A method comprising: a) providing a hydrocarbon liquid stream (10) produced by pyrolysis of waste plastics; b) introducing the hydrocarbon liquid stream (10) into b.1) a first fractionation unit (T1) to separate a C7 stream top stream (40), a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a product side stream (50) containing alpha-methylstyrene, or b.2) a first fractionation unit (T1) to separate a C7 stream overhead (40) and a stream introduced into a second fractionation unit (T1') to obtain a first fractionation side stream (30), a heavy fraction-containing stream from the bottom (20) and optionally a product side stream (50) containing alpha-methylstyrene, or b.3) a distillation column (D5) to obtain a distilled product stream (220); c) Conduct c.1) feeding the first fractionated side stream (30) obtained in b.1) or b.2) or the distilled product stream (220) obtained in b.3) to a hydroprocessing unit (HP) comprising a hydroprocessing catalyst in the presence of hydrogen to produce a product stream (80, 270) containing ethylbenzene; or c.2) feeding the first fractionated side stream (30) obtained in b.1) or b.2) to a distillation column (D5) to obtain a distilled product stream (220); then feeding the distilled product stream (220) to a hydroprocessing unit (HP) containing a hydroprocessing catalyst in the presence of hydrogen to produce a product stream (270) containing ethylbenzene; d) introducing the ethylbenzene-containing product stream (80, 270) thus obtained in c.1) or c.2) into an ethylbenzene distillation column (D1), thereby recovering a distilled ethylbenzene stream (110) from the top of the column and a stream (120) containing α-methylbenzyl alcohol from the bottom; e) introducing the ethylbenzene product stream (110) into an ethylbenzene oxidation unit, optionally together with fresh ethylbenzene (100), to produce ethylbenzene hydroperoxide by liquid phase oxidation; f) reacting the ethylbenzene hydroperoxide obtained in e) with a propylene stream in the presence of a catalyst in an epoxidation unit to produce crude propylene oxide (300) and a bottom product (310) containing ethylbenzene and α-methylbenzyl alcohol; g) feeding the stream containing α-methylbenzyl alcohol (120) to a second distillation column (D2) to obtain three fractions: a product stream tops (130) containing xylenes, a side stream (150) rich in α-methylbenzyl alcohol and a bottoms stream (140) containing α-methylbenzyl alcohol and higher boiling products; Alternatively, the stream (120) containing α-methylbenzyl alcohol is introduced into a second distillation column (D2), and a stream product top distillate (130) containing xylenes and a bottom stream introduced into an additional distillation column (D2') are separated to obtain a top stream (150) rich in α-methylbenzyl alcohol and a heavy bottom stream (140) containing α-methylbenzyl alcohol and higher boiling point products; h) introducing the side stream (150) rich in α-methylbenzyl alcohol into a dehydration unit (DH1) containing a catalyst, thereby obtaining a phase-separated crude styrene monomer (160) and water; i) feeding the crude styrene phase (160) thus obtained to a distillation column (D3), in which a stream (170) containing ethylbenzene is separated from the top, and the bottom product (180) is fed to a styrene product column (D4), in which styrene monomer (190) is obtained at the top and heavy products (200) are obtained at the bottom; j) feeding the heavy bottom product streams (140 and 200) from the second distillation column and the additional distillation columns (D2, D2') and the styrene product column (D4) to a distillation column (D5); the distilled product stream (220) thus obtained together with the ethylbenzene-containing stream (170) to the hydroprocessing unit (HP) of step c).

2. The method of claim 1, wherein: The first fractionated side stream (30) obtained after option b1) or option b2) comprises a benzene content of 0 to 250 ppmw.

3. The method according to any one of claims 1 to 2, wherein: The first fractionated side stream ( 30 ) obtained after option b1) or option b2) comprises a styrene and ethylbenzene content of 89 to 99% by weight, relative to the total weight of the stream.

4. The method according to any one of claims 1 to 3, wherein: The first fractionated pyrolysis oil (30) side stream obtained after option b1) or option b2) contains 0.01 mgKOH / g to 1 mgKOH / g of acid containing compounds measured by standard test method ASTM D664.

5. The method according to any one of claims 1 to 4, wherein: The first fractionated side stream (30) obtained after option b1) or option b2) comprises: i. 89 to 99% by weight of styrene monomer and ethylbenzene, preferably 90 to 98% by weight, More preferably, 93% to 95% by weight; ii. 0 to 500 ppm by weight of benzene, preferably 50 ppm by weight to 300 ppm by weight, more preferably 100 ppm by weight to 250 ppm by weight; iii. 0 to 1 wt% toluene, preferably 0.01 to 0.5 wt%, more preferably 0.1 to 0.3 wt%; iv. 0 to 2.5 wt% of xylene, preferably 0.1 to 2 wt%, more preferably 0.5 to 1.5 wt%; v. 0 to 1.5 wt% of a C9 aromatic compound other than α-methylstyrene, which is a mixture of cumene, propenylbenzene, n-propylbenzene, allylbenzene, ethyltoluene and methylstyrene, preferably 0.01 to 1 wt%, more preferably 0.1 to 0.8 wt%; vi. 0 to 5% by weight of α-methylstyrene, preferably 0.1 to 3% by weight, more preferably 1 to 2.5% by weight; vii. 0 to 1.5 wt% of phenylacetylene, preferably 0.0001 to 1 wt%, more preferably 0.001 to 0.5 wt%; viii. 0 to 2500 ppm by weight of heteroatom-containing compounds, preferably 1 ppm by weight to 1250 ppm by weight, more preferably 10 ppm by weight to 250 ppm by weight; ix. 0 to 0.1 wt% of a C10 aromatic compound which is a mixture of divinylbenzene and ethylstyrene, preferably 0.001 to 0.08 wt%, more preferably 0.01 to 0.05 wt%; x. 0 to 1 wt.% of a hydrocarbon selected from (C3-C8)alkanes, (C2-C8)olefins, (C5-C8)cycloalkanes and (C5-C8) One or more compounds of the group consisting of a mixture of cyclic olefins, preferably 0.001 wt% to 0.85 wt%, more preferably 0.01 wt% to 0.5 wt%; xi. 0 to 0.1 wt% of heavy oil fraction, preferably 0.0001 to 0.05 wt%, more preferably 0.001 to 0.01 wt%; xii. 0 to 50 ppm by weight of the metal in the metal-containing compound, preferably 0.01 ppm by weight to 25 ppm by weight, more preferably 0.1 ppm by weight to 10 ppm by weight; xiii. 0.5 ppm by weight to 1500 ppm by weight of heteroatoms in heteroatom-containing compounds, preferably 1 ppm by weight to 500 ppm by weight, more preferably 5 ppm by weight to 100 ppm by weight; and xiv. 0 to 120 ppm by weight of water, preferably 0.1 ppm by weight to 25 ppm by weight, more preferably 1 ppm by weight to 10 ppm by weight.

6. The method according to any one of claims 1 to 5, wherein: After option b.1) or b.2) and before step c), the method further comprises alkali washing or water washing of the first fractionated pyrolysis oil side stream (30).

7. The method according to any one of claims 1 to 6, wherein: The first fractionated pyrolysis oil side stream (30) obtained in b.1) or b.2) is introduced into a hydroprocessing unit (HP) comprising a heterogeneous hydroprocessing catalyst in the presence of hydrogen according to step c.1); and wherein the hydroprocessing unit (HP) is selected from c.1A) Dedicated hydroprocessing unit (HP2); and c.1B) A hydroprocessing unit (HP1) for the acetophenone hydrogenation step, wherein the first fractionation side stream (30) is introduced into the hydroprocessing unit (HP1) together with the product stream distilled from the distillation column (D5).

8. The method of claim 7, wherein: The hydroprocessing unit (HP) of step c.1B) comprises two or more slurry hydrogenation reactors (HP11, HP12 ... HP1 n ); wherein the first fractionation side stream (30) is at different HP1 n The first fractionation side stream (30) is fed to the first hydroprocessing reactor (HP11) to produce a product stream containing ethylbenzene, which is fed to the next subsequent reactor, and the operation is repeated for n reactors until the nth hydroprocessing reactor (HP11) is completed. n ) to obtain a product stream (270) containing ethylbenzene.

9. The method of claim 8, wherein: The first fractionated side stream (30) is separated into two streams at different HP1 n Distribute between reactors.

10. The method according to any one of claims 1 to 6, wherein: In step c), the first fractionated side stream (30) is fed to a distillation column (D5) together with the heavy bottom product streams (140) and (200) to obtain a distilled product stream (220); wherein the distilled product stream (220) is fed to a hydroprocessing unit (HP1) for the acetophenone hydrogenation step.

11. The method according to any one of claims 1 to 10, further comprising converting the heavy residue (155) containing styrene oligomers obtained in the dehydration unit (DH1) into a recovered pyrolysis oil stream (10') in a pyrolysis unit; and introducing the recovered pyrolysis oil stream (10') obtained thereby into a first fractionation unit (T1) or into a distillation tower (D5) together with a hydrocarbon liquid stream (10) produced by pyrolysis of waste plastics.

12. The method according to any one of claims 1 to 11, wherein: The distilled ethylbenzene stream (110) obtained in step d) comprises: 93 to 99% by weight of ethylbenzene, preferably 95 to 99% by weight; 0.001 to 0.1 wt% benzene, preferably 0.01 to 0.05 wt%; 0.01 to 1% by weight of toluene, preferably 0.1 to 0.5% by weight; 0.01 to 1% by weight of o-xylene, preferably 0.1 to 0.5% by weight; 0.01 to 3% by weight of meta-xylene, preferably 0.1 to 1.5% by weight; 0.01 to 3% by weight of p-xylene, preferably 0.1 to 1.5% by weight; 0.01 to 1% by weight of cumene, preferably 0.1 to 0.5% by weight; 1 ppm by weight to 1000 ppm by weight of diethylbenzene, preferably 10 ppm by weight to 100 ppm by weight; 0.0001 to 0.1% by weight of n-propylbenzene, preferably 0.001 to 0.01% by weight; 0.001 to 0.1 wt% of one or more compounds selected from the group consisting of mixtures of (C3-C8)alkanes, (C2-C8)alkenes, (C5-C8)cycloalkanes and (C5-C8)cycloalkenes, preferably 0.01 to 0.06 wt%; 0.01 ppmw to 50 ppmw of heteroatom-containing compounds, preferably 0.1 ppmw to 5 ppmw; and 0.1 ppmw to 250 ppmw of water, preferably 0.1 ppmw to 100 ppmw.

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