Recovery of aliphatic hydrocarbons

Abstract

The invention relates to a process for recovering aliphatic hydrocarbons from a liquid stream comprising aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons, which process involves a) contacting the liquid stream with a stream having a pH higher than 7 and comprising a washing solvent, before and / or after contacting with a stream having a pH lower than 7 and comprising a washing solvent; b) subjecting the washed stream to liquid-liquid extraction with an extraction solvent. Furthermore, the invention relates to a process for recovering aliphatic hydrocarbons from plastics, which process comprises the above-mentioned process; and to a process for steam cracking a hydrocarbon feed comprising aliphatic hydrocarbons recovered in one of the above-mentioned processes.

Description

Technical Field

[0001] This invention relates to a method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feed stream comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons; to a method for recovering aliphatic hydrocarbons from plastics, the method comprising the above-described methods; and to a method for steam cracking hydrocarbon feedstocks comprising aliphatic hydrocarbons recovered in one of the above-described methods. Background Technology

[0002] Waste plastics can be converted into valuable chemicals, including olefins and aromatic hydrocarbons, through plastic cracking (e.g., pyrolysis). The pyrolysis of plastics produces a product stream containing hydrocarbons with a wide boiling range. These hydrocarbons can be further cracked in a steam cracker to produce valuable chemicals, including monomers such as ethylene and propylene, which can be used to manufacture new plastics.

[0003] WO2020212315 discloses a method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feed stream containing aliphatic hydrocarbons and additionally containing aromatic hydrocarbons and / or polar components. The method includes feeding the feed stream and an organic solvent stream into a column; contacting the feed stream with the organic solvent stream; and recovering the aliphatic hydrocarbons by liquid-liquid extraction of the aromatic hydrocarbons and / or polar components with the organic solvent.

[0004] According to WO2020212315 above, the liquid hydrocarbon feedstock stream may include liquid products generated by the pyrolysis of waste plastics. Furthermore, according to WO2020212315, the organic solvent may be selected from the group consisting of: glycols and triols, including any isomers of monoethylene glycol, monopropylene glycol, and butanediol; ethylene glycol ethers, including oligoethylene glycols (including diethylene glycol and tetraethylene glycol) and their ethers (including diethylene glycol dimethyl ether); amides, including N-alkylpyrrolidones (including N-methylpyrrolidone) and dialkylformamides (including dimethylformamide); dialkyl sulfoxides, including dimethyl sulfoxide; sulfolane; N-formylmorpholine (NFM); and furan ring-containing components, including furfural, 2-methyl-furan, and furfuryl alcohol.

[0005] Furthermore, US20180355256 discloses a method for obtaining fuel from plastics, the method comprising subjecting a quantity of plastics to a pyrolysis process, thereby converting at least a portion of the plastics into crude fuel; and extracting the fuel in a directly usable form by: 1) a first extraction step comprising countercurrent liquid-liquid extraction using one or more extraction solvents to extract one or more impurities from the crude fuel; and 2) a second extraction step comprising countercurrent extraction of the resulting contaminated extraction solvent from the first extraction step. In cases such as US20180355256... Figure 2In the method shown, crude fuel (i.e., crude diesel oil) produced by the pyrolysis of plastics is first extracted with N-methyl-2-pyrrolidone (NMP) to extract one or more impurities, including sulfur compounds and aromatic compounds, from the crude fuel. A second extraction step is then performed using water to contaminate the NMP from the first extraction step, increasing the polarity of the contaminated extraction solvent and thus separating the impurities. In a final step, the NMP contaminated with water from the second extraction step is distilled using a standard distillation column, resulting in recycled water and recycled NMP.

[0006] Even though a certain amount of heteroatom-containing organic contaminants can be removed from the crude fuel (feed) in the first extraction step in the aforementioned US20180355256 method, the resulting purified fuel may still contain a relatively large amount of these contaminants. This is of particular concern when feeding such purified oil into a steam cracker instead of using it as fuel, as these contaminants have a negative impact on the yield, selectivity and reliability of the steam cracker.

[0007] Furthermore, this crude raw material may contain other contaminants, such as silicon-containing compounds, including silica and siloxane compounds. For example, silica is known to be used as a filler material, such as glass fiber (SiO2), to improve the mechanical properties of plastics. Additionally, the siloxane compounds may be derived from polysiloxane polymers containing -R-2Si-O-SiR2- chains.

[0008] Such silicon-containing compounds may not be removed by extraction solvents (such as NMP) and thus end up in the raffinate stream. Furthermore, other contaminants in this crude feedstock can be metals. For example, calcite (CaCO3) and wollastonite (CaSiO3) are also known as filler materials in plastics. Some of these metals may not end up in the raffinate stream but may form complexes with the extraction solvent and ultimately remain in the raffinate stream. Such silicon-containing compounds and metals from the raffinate stream also have a negative impact when present in the feedstock of steam crackers, as they can cause scaling in the tubular furnace within the steam cracker.

[0009] Typically, hydrocarbon feedstocks must meet certain specifications (maximum concentrations) for many heteroatom-containing organic contaminants (especially those containing chlorine, nitrogen, and / or oxygen) and for other contaminants (such as the aforementioned silicon compounds and metals) before they can be fed into the steam cracker.

[0010] Extraction methods similar to those disclosed in US20180355256 may involve a crude feedstock containing such a high amount of heteroatom-containing organic contaminants and any other contaminants, such as pyrolysis oil made from waste plastics, that such a high level cannot be achieved by applying this extraction method alone to produce a purified feedstock (e.g., feedstock to a steam cracker) with sufficient quality to meet the aforementioned specifications.

[0011] Furthermore, during the extraction process, the contaminants may accumulate in the recycled water (the extraction solvent in the second extraction step) and the recycled NMP (the extraction solvent in the first extraction step), which ultimately leads to a further reduction in the quality of the final purified product.

[0012] In the method described in US20180355256, the second extraction step uses an aqueous extraction solvent to extract not only the NMP to be extracted but also a portion of the contaminants, potentially leading to their accumulation. Therefore, the feed to the distillation column (as described in US20180355256)... Figure 2 The purified oil may still contain a certain amount of heteroatom-containing organic contaminants, especially oxygen-containing organic contaminants, particularly highly polar components such as phenol. The distillation may cause some of these contaminants to separate along with the recirculated water, as water and such contaminants can form azeotropes, thus reducing the quality of the recirculated water stream. If the recirculated water is recycled to the column used in the second extraction step, the concentration of these contaminants in the recirculated NMP to be used in the first extraction step will also increase (accumulate). This may lead to a decrease in the efficiency of both the first and second extraction steps. This accumulation of these contaminants (in the recirculated NMP) may result in the purified oil still containing a relatively large amount of these contaminants, which warrants particular attention when feeding such purified oil to a steam cracker.

[0013] Furthermore, in practice, feedstocks may contain other contaminants, such as salts, especially liquid hydrocarbon feedstock streams obtained from the pyrolysis of plastics. For example, as mentioned above, such feedstocks may contain calcite (CaCO3) and wollastonite (CaSiO3). These salts may ultimately be present in the extractant stream, for example, when the extraction solvent is NMP (such as US20180355256). Figure 2 In the case of column A used in the method, such salts will eventually be present in the water-NMP bottom stream from column B used in the method, and then enter distillation column C, where they will be concentrated in the NMP bottom stream. These salts will then be recycled along with NMP, and their concentration will accumulate over time. Furthermore, because NMP and other organic solvents have limited solubility for salts, these salts will begin to precipitate in the distillation column, leading to scaling.

[0014] There is an ongoing need to develop improved methods for recovering aliphatic hydrocarbons from liquid streams containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, which may originate from cracked waste plastics, particularly mixed waste plastics, especially before feeding such recovered aliphatic hydrocarbons into a steam cracker. The object of this invention is to provide a technically advantageous, efficient, and affordable method for recovering aliphatic hydrocarbons from such liquid streams, particularly one that does not suffer from one or more of the aforementioned disadvantages, as discussed above in conjunction with US20180355256. This technically advantageous method will preferably result in relatively low energy requirements and / or relatively low capital expenditures. Summary of the Invention

[0015] Surprisingly, the inventors have found that this method can be provided by the following steps: a) contacting a liquid stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons with a stream containing a washing solvent a) having a pH higher than 7, and before and / or after contacting a stream containing a washing solvent a) having a pH lower than 7, thereby removing the heteroatom-containing organic compounds; and b) performing a liquid-liquid extraction with an extraction solvent b) containing one or more heteroatoms on the stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons produced by the washing step a).

[0016] Therefore, the present invention relates to a method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feedstock comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, the method comprising the following steps:

[0017] a) Mixing at least a portion of a liquid hydrocarbon feed stream with a stream containing a washing solvent a) having a pH greater than 7 and containing one or more heteroatoms, and separating the resulting mixture into a first stream containing the washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons.

[0018] Step a) further includes:

[0019] a1) Prior to mixing with the stream having a pH higher than 7: mixing at least a portion of the liquid hydrocarbon feed stream with a stream having a pH lower than 7 and containing a washing solvent a) containing one or more heteroatoms, and separating the resulting mixture into a first stream containing washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons, and mixing at least a portion of the second stream with the stream having a pH higher than 7, and / or

[0020] a2) After mixing with the stream having a pH higher than 7: at least a portion of the second stream obtained from the mixing with the stream having a pH higher than 7 and the separation into a first stream and a second stream is mixed with a stream having a pH lower than 7 and containing a washing solvent a) containing one or more heteroatoms; the resulting mixture is then separated into a first stream containing washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons; and at least a portion of the second stream is fed to step b); and

[0021] b) Contacting at least a portion of the second stream produced by step a) with an extraction solvent b) containing one or more heteroatoms, and performing liquid-liquid extraction of the stream with the extraction solvent b) to produce a first stream containing aliphatic hydrocarbons and optionally heteroatom-containing organic compounds and a second stream containing the extraction solvent b), heteroatom-containing organic compounds and optionally aromatic hydrocarbons.

[0022] Advantageously, in this invention, a washing step in the method of the invention removes heteroatom-containing organic compounds and optionally the other contaminants that may ultimately be present in the final purified hydrocarbon product by applying an extraction step alone. This washing step comprises multiple washing steps, at least one of which is performed at a pH above 7 (“alkaline”) and at least one washing step is performed at a pH below 7 (“acidic”). This may advantageously result in a final hydrocarbon product of sufficiently high quality that meets certain specifications (maximum concentrations) for many heteroatom-containing organic contaminants (particularly chlorine, nitrogen, and / or oxygen-containing contaminants) and for any other contaminants; that is, the hydrocarbon feed should meet these specifications before it can be fed into the steam cracker. In this specification, the term “other contaminants” refers to contaminants in or originating from the liquid hydrocarbon feed stream, other than heteroatom-containing organic contaminants (heteroatom-containing organic compounds), which may include salts and / or silicon-containing compounds and / or metals.

[0023] Furthermore, advantageously, in the washing step a) preceding the extraction step b), a portion of heteroatom-containing organic compounds (especially oxygen-containing organic contaminants, particularly highly polar components including, for example, phenol) are removed. In this step a), at least a portion of the liquid hydrocarbon feed stream is contacted with the washing solvent a) first at a high pH (>7) and then at a low pH (<7), or vice versa, i.e., first at a low pH (<7) and then at a high pH (>7), thereby avoiding or reducing the accumulation of such contaminants in the downstream portion of the method of the invention. An intermediate rinsing step may be provided between the acid washing step and the alkaline washing step, wherein a neutral washing solvent feed stream (pH of about 7) is used. Furthermore, advantageously, in the washing step a), any other contaminants from the feed stream are also removed, thereby preventing some of these other contaminants, including salts, from accumulating to higher concentrations in the downstream section, and thus simultaneously preventing scaling in the downstream distillation column due to the precipitation of such salts.

[0024] Furthermore, the heteroatom-containing organic compounds and optional other contaminants extracted in the second (extraction) stream produced by step b) containing extraction solvent b), heteroatom-containing organic compounds, and optional aromatic hydrocarbons can accumulate in any recycled extraction solvent b) stream entering step b), as described above. The heteroatom-containing organic compounds causing this accumulation can be the most polar components among all the heteroatom-containing organic compounds extracted in step b) of the method of the invention. In this case, advantageously, by washing step a), a portion of these heteroatom-containing organic compounds and other optional contaminants has been removed from the feed stream prior to extraction step b), thereby preventing the accumulation in any recycled extraction solvent b) stream. The relatively pure extraction solvent b) stream can then advantageously be recycled to step b) and used to extract additional heteroatom-containing organic compounds and optional aromatic hydrocarbons from the fresh feed. Therefore, in this invention, it is advantageous to remove the aforementioned contaminants (including heteroatom-containing organic compounds and any other contaminants (including any salts)) that have accumulated or may accumulate as described above in the washing step a) prior to the extraction step b), thereby preventing the accumulation of such contaminants in any recycled stream in the method of this invention and ultimately resulting in a relatively pure final hydrocarbon product.

[0025] Due to the pre-washing step a) described above in this invention, the need to apply other cumbersome methods to mitigate the accumulation of these contaminants is eliminated or significantly reduced. For example, the need to discharge a portion of any recycle stream (e.g., any recycle extraction solvent b) before recirculation is eliminated or significantly reduced, wherein (i) such a discharge stream is discarded, resulting in the loss of the extraction solvent, or (ii) the extraction solvent can be recovered from such a discharge stream, for example, by distillation, which is cumbersome.

[0026] Furthermore, in the washing step a) of the method of the present invention, other contaminants that should preferably not ultimately be present in the raffinate stream produced by the extraction step b) can also be advantageously removed simultaneously with the aforementioned heteroatom-containing organic contaminants and optionally salts. For example, the aforementioned metals and silicon-containing compounds (such as silica and siloxane compounds) can also be advantageously removed in step a) of the method of the present invention, thereby preventing any negative impact that such contaminants may have in subsequent processes (such as steam cracking processes). In step a), an acidic stream containing washing solvent a) (pH below 7) can advantageously remove heteroatom-containing organic compounds and / or metals, while an alkaline stream containing washing solvent a) (pH above 7) can advantageously remove heteroatom-containing organic compounds and / or silicon-containing compounds.

[0027] Furthermore, the present invention relates to a method for recovering aliphatic hydrocarbons from plastics, wherein at least a portion of these plastics contains heteroatom-containing organic compounds, the method comprising the following steps:

[0028] (I) Cracking the plastic and recovering hydrocarbon products, said hydrocarbon products comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons; and

[0029] (II) Perform the above-described method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feed stream, the liquid hydrocarbon feed stream comprising at least a portion of the hydrocarbon products obtained in step (I).

[0030] Furthermore, the present invention relates to a method for steam cracking hydrocarbon feedstock, wherein the hydrocarbon feedstock comprises aliphatic hydrocarbons recovered in one of the methods described above for recovering aliphatic hydrocarbons. Attached Figure Description

[0031] Figure 1 An embodiment of the method for recovering aliphatic hydrocarbons according to the present invention is shown.

[0032] Figure 2 Another implementation of the above method is shown. Detailed Implementation

[0033] Each method of the present invention includes multiple steps. Furthermore, the method may include one or more intermediate steps between consecutive steps. Additionally, the method may include one or more additional steps before the first step and / or after the last step. For example, in the case where the method includes steps a), b), and c), the method may include one or more intermediate steps between steps a) and b) and between steps b) and c). Furthermore, the method may include one or more additional steps before step a) and / or after step c).

[0034] In this specification, phrases such as "step y) includes performing on at least a portion of the flow generated by step x)" mean "step y) includes performing on a portion or all of the flow generated by step x), or similarly, "step y) includes performing on a portion or all of the flow generated by step x). For example, the flow generated by step x) may be separated into one or more portions, wherein step y) may be performed on at least one of these portions. Furthermore, for example, an intermediate step between step x) and step y) may be performed on the flow generated by step x) to generate another flow, wherein step y) may be performed on at least a portion of that additional flow.

[0035] Although the methods of the present invention and the feed streams and compositions used in the methods are described as "comprising", "containing" or "including" one or more of the different steps or components, they may also be "consistently substantially of the one or more different steps or components" or "consistently of the one or more different steps or components".

[0036] In the context of this invention, when the feed stream contains two or more components, these components are selected in a total amount not exceeding 100%.

[0037] Furthermore, when referencing upper and lower bounds for properties, it also implies the range of values ​​limited by a combination of either the upper or lower bound.

[0038] In this specification, “substantially none” in relation to the amount of a particular component in the feed stream means that, based on the amount (i.e., weight) of the feed stream, the amount of the component under consideration is at most 1,000 ppmw (parts per million weight), preferably at most 500 ppmw, more preferably at most 100 ppmw, more preferably at most 50 ppmw, more preferably at most 30 ppmw, more preferably at most 20 ppmw, and most preferably at most 10 ppmw.

[0039] In this specification, “top flow” or “bottom flow” from the tower refers to the flow of material leaving the tower from the top or bottom of the tower at a location between 0% and 30%, more preferably between 0% and 20%, or even more preferably between 0% and 10%, based on the total tower length.

[0040] Unless otherwise specified, when boiling point is mentioned in this specification, it refers to the boiling point at a pressure of 760 mmHg (101.3 kPa).

[0041] In this specification, the term "heteroatom-containing compound" refers to organic compounds containing heteroatoms and / or inorganic compounds containing heteroatoms, including salts.

[0042] Liquid hydrocarbon feedstock

[0043] In this invention, the liquid hydrocarbon feed stream comprises aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons.

[0044] Preferably, the liquid hydrocarbon feed stream comprises both aliphatic hydrocarbons having a boiling point of 30°C to 300°C and aliphatic hydrocarbons having a boiling point higher than 300°C to 600°C, in a weight ratio of 99:1 to 1:99. Based on the total amount of aliphatic hydrocarbons having a boiling point of 30°C to 600°C, the amount of aliphatic hydrocarbons having a boiling point of 30°C to 300°C can be up to 99% by weight, or up to 80% by weight, or up to 60% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 10% by weight. Furthermore, based on the total amount of aliphatic hydrocarbons having a boiling point of 30°C to 600°C, the amount of aliphatic hydrocarbons having a boiling point of 30°C to 300°C can be at least 1% by weight, or at least 5% by weight, or at least 10% by weight, or at least 20% by weight, or at least 30% by weight.

[0045] Therefore, advantageously, the liquid hydrocarbon feed stream can contain varying amounts of aliphatic hydrocarbons within a wide boiling point range of 30°C to 600°C. Consequently, similar to the boiling point, the number of carbon atoms in the aliphatic hydrocarbons in the liquid hydrocarbon feed stream can also vary within a wide range, for example, from 5 to 50 carbon atoms. The number of carbon atoms in the aliphatic hydrocarbons in the liquid hydrocarbon feed stream can be at least 4, or at least 5, or at least 6, and can be at most 50, or at most 40, or at most 30, or at most 20.

[0046] Based on the total weight of the liquid hydrocarbon feed stream, the amount of aliphatic hydrocarbons in the liquid hydrocarbon feed stream may be at least 30% by weight, or at least 50% by weight, or at least 80% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight, and may be less than 100% by weight, or at most 99% by weight, or at most 90% by weight, or at most 80% by weight, or at most 70% by weight. Aliphatic hydrocarbons may be cyclic, straight-chain, or branched.

[0047] The aliphatic hydrocarbons in the liquid hydrocarbon feed stream may include non-olefin (paraffinic) aliphatic compounds and olefinic aliphatic compounds. Based on the total weight of the liquid hydrocarbon feed stream, the amount of paraffinic aliphatic compounds in the liquid hydrocarbon feed stream may be at least 20% by weight, or at least 40% by weight, or at least 60% by weight, or at least 80% by weight, and may be less than 100% by weight, or at most 99% by weight, or at most 80% by weight, or at most 60% by weight. Furthermore, based on the total weight of the liquid hydrocarbon feed stream, the amount of olefinic aliphatic compounds in the liquid hydrocarbon feed stream may be less than 100% by weight, or at least 20% by weight, or at least 40% by weight, or at least 60% by weight, or at least 80% by weight, and may be at most 99% by weight, or at most 80% by weight, or at most 60% by weight.

[0048] Furthermore, the olefinic compounds may include aliphatic compounds (monoolefins) having one carbon-carbon double bond and / or aliphatic compounds having two or more carbon-carbon double bonds, the latter of which may be conjugated or non-conjugated. That is, the two or more carbon-carbon double bonds may be conjugated or non-conjugated. Aliphatic compounds having two or more carbon-carbon double bonds may include compounds having double bonds at the α and ω positions. Based on the total weight of the liquid hydrocarbon feed stream, the amount of monoolefins in the liquid hydrocarbon feed stream may be at least 20% by weight, or at least 40% by weight, or at least 60% by weight, or at least 80% by weight, and may be less than 100% by weight, or at most 99% by weight, or at most 80% by weight, or at most 60% by weight. Furthermore, based on the total weight of the liquid hydrocarbon feed stream, the amount of conjugated aliphatic compounds having two or more carbon-carbon double bonds in the liquid hydrocarbon feed stream may be greater than 0% by weight, or at least 10% by weight, or at least 20% by weight, or at least 40% by weight, or at least 60% by weight, and may be up to 80% by weight, or up to 60% by weight, or up to 40% by weight.

[0049] In this specification, aliphatic hydrocarbons containing one or more heteroatoms are "heteroatom-containing organic compounds," as further described below. Unless expressly indicated or otherwise specified by context, the term "aliphatic hydrocarbon" in this specification does not include aliphatic hydrocarbons containing heteroatoms. Furthermore, unless expressly indicated or otherwise specified by context, the term "aliphatic hydrocarbon" in this specification does not include conjugated aliphatic compounds having two or more carbon-carbon double bonds.

[0050] In addition to the aforementioned aliphatic hydrocarbons, the liquid hydrocarbon feed stream also contains heteroatom-containing organic compounds and optional aromatic hydrocarbons.

[0051] Based on the total weight of the liquid hydrocarbon feed stream, the amount of aromatic hydrocarbons in the liquid hydrocarbon feed stream may be 0% by weight, or greater than 0% by weight, or at least 5% by weight, or at least 10% by weight, or at least 15% by weight, or at least 20% by weight, or at least 25% by weight, or at least 30% by weight, and may be up to 50% by weight, or up to 40% by weight, or up to 30% by weight, or up to 20% by weight. Aromatic hydrocarbons may include monocyclic aromatic hydrocarbons and / or polycyclic aromatic hydrocarbons. An example of a monocyclic aromatic hydrocarbon is styrene. Polycyclic aromatic hydrocarbons may include unfused polycyclic aromatic hydrocarbons and / or fused polycyclic aromatic hydrocarbons. An example of an unfused polycyclic aromatic hydrocarbon is oligostyrene. Styrene and oligostyrene may be derived from polystyrene. Examples of fused polycyclic aromatic hydrocarbons are naphthalene and anthracene, as well as alkylnaphthalene and alkylanthracene. One or more aromatic rings in an aromatic hydrocarbon may be substituted with one or more hydrocarbon groups, including alkyl groups (saturated) and alkylene groups (unsaturated).

[0052] In this specification, aromatic hydrocarbons containing one or more heteroatoms are "heteroatom-containing organic compounds," as further described below. Unless expressly indicated or otherwise specified by context, the term "aromatic hydrocarbon" does not include heteroatom-containing aromatic hydrocarbons in this specification.

[0053] Furthermore, based on the total weight of the liquid hydrocarbon feed stream, the amount of heteroatom-containing organic compounds in the liquid hydrocarbon feed stream is greater than 0 wt%, and may be at least 0.5 wt%, or at least 1 wt%, or at least 3 wt%, or at least 5 wt%, or at least 10 wt%, or at least 15 wt%, or at least 20 wt%, and may be at most 30 wt%, or at most 20 wt%, or at most 10 wt%, or at most 5 wt%.

[0054] The heteroatom-containing organic compound in the liquid hydrocarbon feed stream contains one or more heteroatoms, which can be oxygen, nitrogen, sulfur, and / or halogens (such as chlorine), suitably oxygen, nitrogen, and / or halogens. The heteroatom-containing organic compound may contain one or more of the following moieties: amine, imine, nitrile, alcohol, ether, ketone, aldehyde, ester, acid, amide, carbamate (sometimes called ethyl carbamate), and urea.

[0055] Furthermore, the aforementioned heteroatom-containing organic compounds can be aliphatic or aromatic. An example of aliphatic organic compounds containing heteroatoms is oligomeric polyvinyl chloride (PVC). Oligomeric PVC can be derived from polyvinyl chloride. Aromatic organic compounds containing heteroatoms can include heteroatom-containing monocyclic aromatic organic compounds and / or heteroatom-containing polycyclic aromatic organic compounds. Examples of heteroatom-containing monocyclic aromatic organic compounds are terephthalic acid and benzoic acid. An example of heteroatom-containing polycyclic aromatic organic compounds is oligomeric polyethylene terephthalate (PET). Terephthalic acid, benzoic acid, and oligomeric PET can be derived from polyethylene terephthalate. Examples of nitrogen-containing organic compounds are compounds derived from polyurethanes and polyamides (including nylon).

[0056] Unless expressly indicated or otherwise specified in the context, the term "heteroatom-containing organic compound" in this specification refers to an organic compound containing heteroatoms that is in or derived from a liquid hydrocarbon feedstock stream. Furthermore, unless expressly indicated or otherwise specified in the context, the term "heteroatom-containing organic compound" in this specification does not include extraction solvents and / or washing solvents as defined herein.

[0057] Additionally, the liquid hydrocarbon feedstock stream may contain salts. These salts may include organic and / or inorganic salts. These salts may contain ammonium, alkali metals, alkaline earth metals, or transition metals as cations, and carboxylates, sulfates, phosphates, or halide ions as anions.

[0058] In addition, liquid hydrocarbon feedstock streams may also contain silicon-containing compounds, such as silicon dioxide and siloxane compounds.

[0059] In addition, liquid hydrocarbon feedstock streams may contain metals.

[0060] Preferably, at least a portion of the components in the liquid hydrocarbon feedstock stream, which contains aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, are synthetic compounds, rather than natural compounds present in petroleum, for example. Such synthetic compounds include compounds derived from the pyrolysis of biomass-synthesized plastics, such as polyethylene synthesized from bioethanol through the dehydration of ethanol and subsequent polymerization of the resulting ethylene.

[0061] Furthermore, since heteroatom-containing organic compounds and any other contaminants are readily removed in the method of the present invention, the feed of the method of the present invention can advantageously tolerate relatively large quantities of such heteroatom-containing organic compounds and other contaminants. Therefore, waste plastics that can be pyrolyzed to produce the feed of the method may include heteroatom-containing plastics such as polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyurethane (PU). In particular, pyrolyzable mixtures of waste plastics contain, in addition to heteroatom-free plastics such as polyethylene (PE) and polypropylene (PP), a relatively large quantity of such heteroatom-containing plastics.

[0062] Step a) — Pre-washing of the liquid hydrocarbon feed stream

[0063] In step a) of the method of the present invention, prior to extraction step b), at least a portion of the liquid hydrocarbon feed stream is contacted with washing solvent a) to remove heteroatom-containing organic compounds and optionally other contaminants from the stream. Therefore, step a) precedes extraction step b) of the method of the present invention.

[0064] Step a) comprises mixing at least a portion of a liquid hydrocarbon feed stream with a stream containing a washing solvent a) having a pH greater than 7 and containing one or more heteroatoms, and separating the resulting mixture into a first stream containing the washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons. At least a portion of the second stream produced by step a) is fed into step b), that is, contacted with the extraction solvent b) in step b).

[0065] Furthermore, in step a) of the method of the present invention, in addition to the washing step using a stream containing washing solvent a) and having a pH higher than 7 (“alkaline”) and separate from that washing step, a washing step using a stream containing washing solvent a) and having a pH lower than 7 (“acidic”) is also performed. The alkaline washing step and the acid washing step described in step a) can be performed in any order. However, it is preferred that the acid washing step be performed first in step a), followed by the alkaline washing step.

[0066] Therefore, apart from the alkaline washing step and separate from that alkaline washing step, step a) of the method of the present invention further includes:

[0067] a1) Prior to mixing with the stream having a pH higher than 7: mixing at least a portion of the liquid hydrocarbon feed stream with a stream having a pH lower than 7 and containing a washing solvent a) containing one or more heteroatoms, and separating the resulting mixture into a first stream containing washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons, and mixing at least a portion of the second stream with the stream having a pH higher than 7, and / or

[0068] a2) After mixing with the stream having a pH higher than 7: at least a portion of the second stream obtained by mixing with the stream having a pH higher than 7 and separating it into a first stream and a second stream is mixed with a stream having a pH lower than 7 and containing a washing solvent a) containing one or more heteroatoms, and the resulting mixture is separated into a first stream containing washing solvent a) and a heteroatom-containing compound and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons, and at least a portion of the second stream is fed to step b).

[0069] Furthermore, in the method of the present invention, each washing step in step a) can be performed consecutively multiple times, that is, at least twice, preferably twice or three times, more preferably twice. The latter means that a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, optional other contaminants, and optional aromatic hydrocarbons, generated by the first step a) (or the preceding step a)), is fed to a second step a) (or the subsequent step a)), wherein additional heteroatom-containing organic compounds and optional other contaminants are removed from the stream by contacting at least a portion of the second stream with washing solvent a). The second step a) further includes mixing at least a portion of the stream with washing solvent a), and separating the resulting mixture into a first stream containing washing solvent a), heteroatom-containing compounds, and optional other contaminants, and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optional aromatic hydrocarbons. At least a portion of the second stream generated by the second step a) is fed to step b) (that is, contacted with extraction solvent b) in step b), or to another step a). In addition, at least a portion of the first stream generated by the second step a) (or by any subsequent step a) may be fed to the first step a) (or to any of the aforementioned steps a), such as to provide washing solvent a) to such a first or aforementioned step a).

[0070] Depending on the partition coefficient, heteroatom-containing organic compounds and any aromatic hydrocarbons also ultimately exist to some extent in the second stream produced by step a), wherein the second stream is more hydrophobic than the first stream. Therefore, the second stream contains, in addition to aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons. The first and second streams may also contain conjugated aliphatic compounds having two or more carbon-carbon double bonds.

[0071] In step a), a washing solvent a) is added independently of the liquid hydrocarbon feed stream, except for any washing solvent a) (e.g., water) that may be present in and mixed with the subsequent feed stream. In step a), it is preferable that the feed stream containing the washing solvent a) to be added does not contain or substantially does not contain heteroatom-containing organic compounds, and does not contain or substantially does not contain other contaminants to be removed from the liquid hydrocarbon feed stream, thereby enhancing the efficiency of removing such contaminants from the liquid hydrocarbon feed stream.

[0072] In step a) of the method of the present invention, at least a portion of the liquid hydrocarbon feed stream is contacted with the washing solvent a). Furthermore, in step a), the feed stream may also be contacted with an adsorption reagent, preferably simultaneously, as further described below with respect to adsorption step (i).

[0073] The washing solvent a) in step a) contains one or more heteroatoms, which may be oxygen, nitrogen, and / or sulfur. Preferably, the washing solvent a) is miscible or has relatively low miscibility in heptane. Preferably, the washing solvent a) is miscible in heptane such that, based on the weight of heptane, at most 10% by weight, or at most 3% by weight, or at most 1% by weight, or at most 0.5% by weight, or at most 0.1% by weight of the washing solvent a) is miscible in heptane. Furthermore, it is preferred that the miscibility of the washing solvent a) in heptane is lower than that of the extraction solvent b) in heptane. The miscibility of one compound in another compound (such as heptane) can be determined by any common method known to those skilled in the art (including ASTM Method D1476). When reference is made in this specification to the miscibility of one compound in another compound, this refers to miscibility at 25°C.

[0074] The washing solvent in step a) is measured at 25°C as the Hansen solubility parameter relative to heptane, distance R. a，庚烷 It can be at least 10 MPa 1 / 2 Preferably at least 20 MPa 1 / 2 More preferably at least 30 MPa 1 / 2 More preferably at least 40 MPa 1 / 2 Furthermore, the R of the washing solvent a) a，庚烷 It can be up to 55MPa 1 / 2 More preferably up to 50 MPa 1 / 2 More preferably up to 45 MPa 1 / 2 For example, the R of water a， 45MPa 1 / 2 The Hansen solubility parameter is further described below with respect to the extraction solvent b) used in step b).

[0075] Furthermore, the sodium chloride solubility of the washing solvent a) in step a) measured at 25°C, in grams of NaCl per 100g of solvent, can be at least 0.1g / 100g, preferably at least 0.3g / 100g, more preferably at least 0.5g / 100g, more preferably at least 0.7g / 100g, more preferably at least 1g / 100g, more preferably at least 2g / 100g, more preferably at least 3g / 100g, more preferably at least 4g / 100g, and most preferably at least 5g / 100g, and can be at most 50g / 100g, or at most 40g / 100g, or at most 36g / 100g. For example, the sodium chloride solubility in water is 36g / 100g.

[0076] Furthermore, the washing solvent in step a) may comprise one or more solvents selected from water, ammonia, and organic solvents, wherein the Hansen solubility parameter relative to diethylammonium acetate, measured at 25°C, is a distance R. a，DEAA up to 15 MPa 1 / 2 Preferably at most 13 MPa 1 / 2 More preferably up to 11 MPa 1 / 2 Furthermore, the R of the washing solvent a) a，DEAA It can be at least 5MPa 1 / 2 Preferably at least 8MPa 1 / 2 More preferably at least 10 MPa 1 / 2 For example, the R of monoethylene glycol (MEG) a，DEAA 12MPa 1 / 2 Furthermore, preferably, the organic solvent of washing solvent a) has a greater R than that of the same solvent. a，DEAA R a，庚烷 Wherein R a，庚烷 With R a，DEAA The difference is at least 15 MPa 1 / 2 More preferably at least 16 MPa 1 / 2 The most preferred pressure is at least 17 MPa. 1 / 2 Furthermore, preferably, the R a，庚烷 With R a，DEAA The difference is at most 25 MPa 1 / 2 More preferably up to 22 MPa 1 / 2 The optimal pressure is at most 20 MPa. 1 / 2 For example, the R of monoethylene glycol. a，庚烷 With R a，DEAA The difference is 16.3 MPa 1 / 2 .

[0077] As mentioned above, the extraction solvent b) and washing solvent a) preferably have different miscibility in heptane; in this case, solvent a) and solvent b) are not the same. Specifically, the distance R between the Hansen solubility parameter of washing solvent a) relative to heptane, measured at 25°C, is significant. a，庚烷 The R value is greater than that of extraction solvent b). a，庚烷 Preferably, the R of solvent a) and solvent b) a，庚烷 The difference is at least 1 MPa 1 / 2 More preferably at least 5 MPa 1 / 2 More preferably at least 10 MPa 1 / 2 More preferably at least 15 MPa 1 / 2 More preferably at least 20 MPa 1 / 2 More preferably at least 25 MPa 1 / 2 Furthermore, preferably, the R of solvent a) and solvent b) a，庚烷 The difference is at most 55 MPa 1 / 2 More preferably up to 50 MPa 1 / 2 More preferably up to 45 MPa 1 / 2 More preferably up to 40 MPa 1 / 2 More preferably up to 35 MPa 1 / 2 More preferably up to 30 MPa 1 / 2 .

[0078] Specifically, the washing solvent a) in step a) of the method of the present invention may comprise one or more solvents selected from the group consisting of: water, ammonia, and organic solvents selected from the group consisting of: glycols and triols, including monoethylene glycol (MEG), monopropylene glycol (MPG), and glycerol; glycol ethers, including oligoethylene glycols, including diethylene glycol, triethylene glycol, and tetraethylene glycol, and polyethylene glycol (PEG) with a molecular weight of 200 g / mol to 1,000 g / mol or 200 g / mol to 700 g / mol; amides, including formamides and monoalkyl formamides. The compounds include acetamide, wherein the alkyl group may contain 1 to 8 or 1 to 3 carbon atoms, and the monoalkylformamide and acetamide include methylformamide; dialkyl sulfoxide, wherein the alkyl group may contain 1 to 8 or 1 to 3 carbon atoms, and the dialkyl sulfoxide includes dimethyl sulfoxide (DMSO); sulfone, including sulfolane; hydroxy ester, including lactate, wherein the lactate includes methyl lactate and ethyl lactate; amine compounds, including ethylenediamine, monoethanolamine, diethanolamine and triethanolamine; carbonate compounds, including propylene carbonate and glyceryl carbonate; and cycloalkanone compounds, including dihydro-L-glucanone. Preferably, the washing solvent a) comprises water and one or more of the aforementioned diols and triols (particularly monoethylene glycol (MEG) and glycerol), and glycol ethers (particularly diethylene glycol, triethylene glycol, tetraethylene glycol) and polyethylene glycol (PEG), the PEG having a molecular weight of 200 g / mol to 1,000 g / mol or 200 g / mol to 700 g / mol. More preferably, the washing solvent a) comprises water, and most preferably consists of water. According to the invention, the washing solvent a) may comprise a combination of one or more solvents not mentioned above with one or more solvents mentioned above (e.g., water), wherein the relative amounts of the latter one or more solvents may vary over a wide range and may be as low as, for example, 0.1 wt% based on the total washing solvent.

[0079] In step a), it is preferable that the pH of the alkaline stream containing washing solvent a) (e.g., water) is higher than 7 and the pH is 8 to greater than 14, more preferably 8 to 14, even more preferably 10 to 14, and most preferably 12 to 14. In step a), the pH of the washing solvent a) containing a stream of washing solvent a) being higher than 7 can be provided by adding one or more salts selected from the group consisting of alkali metal carbonates and bicarbonates (including sodium bicarbonate, sodium carbonate, lithium carbonate, lithium bicarbonate, potassium carbonate, and potassium bicarbonate) and alkali metal or alkaline earth metal hydroxides (including lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonium hydroxide). Advantageously, using an alkaline stream containing washing solvent a) having this pH can result in the removal of heteroatom-containing organic compounds and / or silicon-containing compounds. Furthermore, the washing performance of this alkaline stream can be improved by adding an adsorbent agent to step a), as further described below with reference to adsorption step (i).

[0080] In addition, step a) may include two or more steps a), wherein in a first step a), an alkaline feed containing washing solvent a) with a relatively low pH (e.g., 8 to 10) is fed, and in a second or subsequent step a), an alkaline feed containing washing solvent a) with a relatively high pH (e.g., 10 to 14) is fed.

[0081] Furthermore, in step a), it is preferable that the pH of the acid stream containing washing solvent a) (e.g., water) is below 7 and below 1 to 6, more preferably 1 to 6, even more preferably 2 to 5, and most preferably 2 to 4. In step a), the pH of the washing solvent a) stream containing washing solvent a) can be provided to be below 7 by adding an inorganic acid (mineral acid) or an organic acid to the washing solvent a) stream. Suitably, one or more inorganic acids selected from hydrochloric acid, nitric acid, phosphoric acid, boric acid, perchloric acid, hydrofluoric acid, hydroiodic acid, and sulfuric acid can be added. And / or, suitably, one or more organic acids selected from sulfonic acids (including methanesulfonic acid and p-toluenesulfonic acid) and carboxylic acids (including formic acid, oxalic acid, acetic acid, lactic acid, uric acid, malic acid, tartaric acid, and citric acid) can be added. Furthermore, the acidity of the acid stream can be provided by an ion exchange resin or ion exchange polymer, which includes organic polymers such as polystyrene sulfonate or polystyrene crosslinked with divinylbenzene, wherein ion exchange sites are introduced after polymerization by functionalization with acid groups (e.g., sulfonic acid groups or carboxylic acid groups).

[0082] Advantageously, using an acid stream containing washing solvent a) with such a pH can result in the removal of heteroatom-containing organic compounds and / or metals. Furthermore, the washing performance of such an acid stream can be improved by adding an adsorbent to step a), as further described below with reference to adsorption step (i). In particular, when an adsorbent (e.g., clay) is also added, this adsorbent can be advantageously activated by the acid simultaneously, thereby further improving the overall performance. In such cases of “in-situ” acid activation of the adsorbent, the pH of the stream containing washing solvent a) is preferably below 6.5, more preferably 5.4 to 6.5.

[0083] Furthermore, step a) may include two or more steps a), particularly two or more steps a1) or a2) as described above, wherein in the first step a), an acid stream containing washing solvent a) with a relatively high pH (e.g., 4 to 6) is fed in, and in the second or subsequent step a), an acid stream containing washing solvent a) with a relatively low pH (e.g., 2 to 4) is fed in.

[0084] In addition to and separately from the alkaline washing and acid washing steps described in step a) of the method of the present invention, a washing step may also be performed using a stream containing a washing solvent a) (e.g., water) and having a pH of about 7 (“neutral”). The washing performance of such a neutral stream can be improved by adding an adsorption agent to step a), as further described below with reference to adsorption step (i).

[0085] In step a) of the method of the present invention, it is preferable to feed an alkaline feed stream containing washing solvent a) with a pH higher than 7 as described above into the first step a), and the feed stream containing washing solvent a) (e.g., water) in the last step a) before feeding into the second or any other subsequent step a) preferably has a pH of about 7. This additional neutral washing step a) can also be considered a rinsing step, in which no adsorbing agent is preferably added.

[0086] Furthermore, in step a) of the method of the present invention, it is preferable to feed an acidic stream containing washing solvent a) with a pH below 7, as described above, into the first step a), and the pH of the stream containing washing solvent a) (e.g., water) in the last step a) before feeding into the second or any other subsequent step a) is preferably about 7. This additional neutral washing step a) can also be considered a rinsing step, in which no adsorbing agent is preferably added.

[0087] The temperature for step a) can be in the range of 4°C to 400°C, more preferably in the range of 4°C to 300°C, and most preferably in the range of 4°C to 200°C. Specifically, preferably, the temperature is 30°C to 200°C, more preferably 50°C to 170°C, and most preferably 60°C to 150°C. The pressure for step a) can be in the range of atmospheric pressure to 100 bar, more preferably in the range of atmospheric pressure to 20 bar, and most preferably in the range of atmospheric pressure to 6 bar. Specifically, preferably, the pressure is greater than atmospheric pressure to 15 bar, preferably 1.1 bar to 10 bar, more preferably 1.5 bar to 8 bar, and most preferably 2 bar to 6 bar.

[0088] Step a) can be performed continuously or in batches, preferably continuously. Furthermore, the mixing in step a) can be performed in any manner known to those skilled in the art. For example, a mixer can be used upstream of a phase separation device as described below. Additionally, for example, online (or static) mixing can be performed upstream of such a phase separation device. Even further, mixing can be achieved in an extraction tower as described below.

[0089] By adding and mixing the washing solvent a) in step a), step a) produces a first phase comprising the washing solvent a), heteroatom-containing organic compounds, and optionally other contaminants, and a second phase comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, which can be separated into the first and second feed streams described above, respectively. Therefore, advantageously, the washing solvent a), added separately from the liquid hydrocarbon feed stream in step a), removes a portion of the heteroatom-containing organic compounds and any other contaminants from the aliphatic hydrocarbons to be recovered, thereby simultaneously preventing the accumulation of such contaminants in the downstream portion of the method of the invention, and thus improving the stability and reliability of the entire method.

[0090] The phase separation in step a) can be performed by any device capable of separating the two phases, including decanters, flotation units, coalescers, and centrifuges, suitably decanters. The phase separation in step a) can be carried out on a single tray, for example in a decanter, flotation unit, coalescer, or centrifuge. For example, when a decanter is used in step a), the upper phase containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, and the lower phase containing washing solvent a), heteroatom-containing compounds, and optionally other contaminants, can be separated into the second stream and the first stream, respectively.

[0091] Furthermore, step a) can be carried out in an extraction column comprising multiple separation trays. In the latter case, step a) includes contacting at least a portion of the liquid hydrocarbon feed stream with a washing solvent a) in the column, and performing liquid-liquid extraction of the feed stream with the washing solvent a) to obtain a first feed stream containing the washing solvent a), heteroatom-containing compounds and optional other contaminants, and a second feed stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optional aromatic hydrocarbons, wherein the washing solvent a) may be fed into the extraction column at a higher position than the feed stream feed, thereby enabling countercurrent liquid-liquid extraction and producing a top feed stream from the extraction column (the aforementioned "second feed stream") containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optional aromatic hydrocarbons, and a bottom feed stream from the extraction column (the aforementioned "first feed stream") containing the washing solvent a), heteroatom-containing compounds and optional other contaminants.

[0092] The internals of the extraction column described above facilitate the mixing of the feed stream with the washing solvent a). Such column internals are known in the art. Column internals may include packing materials such as Raschig rings, Pall rings, Lessin rings, Bearretsky rings, Dixon rings; sieve plates; or randomly packed structured packing materials, as described in Perry's Chemical Engineer's Handbook. Furthermore, the column may be equipped with a stirring device. For example, a shaft may extend along the column and a rotor and stator may be fixed to the column.

[0093] Therefore, advantageously, in step a) prior to step b), any salts and / or silicon-containing compounds and / or metals originating from the liquid hydrocarbon feed stream have been removed, and portions of heteroatom-containing organic compounds have also been removed from the aliphatic hydrocarbons to be recovered from the liquid hydrocarbon feed stream, thus reducing the need for separation of such heteroatom-containing organic compounds in the subsequent extraction step b). Furthermore, complications associated with such other contaminants, including salts and / or silicon-containing compounds and / or metals originating from the liquid hydrocarbon feed stream, which are discussed in the introduction of this specification, can be advantageously avoided by removing such contaminants (heteroatom-containing organic compounds and any other contaminants) in the first step. Thus, not only can the efficiency of extraction step b) be improved, but such complications caused by these contaminants (heteroatom-containing organic compounds and any other contaminants) can also be advantageously prevented, thereby improving the stability and reliability of the entire method.

[0094] At least a portion of the first feed stream generated from step a), containing washing solvent a), heteroatom-containing compounds, and optionally other contaminants, can be recycled to step a), while another portion can be discharged from the method. Heteroatom-containing organic compounds removed in step a) can optionally be converted into fuel after hydrogenation to remove heteroatoms. Furthermore, the compounds removed in step a) can be further separated into various fractions that can be used as solvents.

[0095] In the case where step a) includes a neutral washing step in addition to the acid washing and alkaline washing steps, multiple steps in series in step a) may be performed such that in the first step a), at least a portion of the liquid hydrocarbon feed stream is mixed with washing solvent a), wherein the pH of the feed stream containing washing solvent a) to be added is below 7 (acid) as described above, and optionally after the removal of any adsorbing agent as further described below with reference to adsorption step (i), the resulting liquid phase may be separated in a decanter, flotation device, coalescer, and centrifuge (suitably in the decanter) as described above, thereby producing a first feed stream containing washing solvent a), heteroatom-containing compounds, and optional other contaminants, and a feed stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, optional other contaminants, and optional aromatic hydrocarbons. A second stream of hydrocarbons, and in a second step a), the first step a) is repeated, but instead a stream containing a washing solvent a) with a pH higher than 7 (base) as described above is used, and in a third step a), at least a portion of the second stream produced by the second step a) is contacted with a stream containing a washing solvent a) with a pH of about 7 as described above, for example, in an extraction tower as described above, and the second stream can be subjected to liquid-liquid extraction with the washing solvent a), thereby producing a first stream containing the washing solvent a), heteroatom-containing compounds and optional other contaminants, and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optional aromatic hydrocarbons, and wherein at least a portion of the second stream produced by the third step a) can be fed to step b). Optionally, if the adsorbent is not removed before separating the first stream and the second stream in the first step a) and / or the second step a), the first stream, particularly the first stream produced by the first step a) and / or the second step a), may contain any adsorbent further described below with respect to adsorption step (i). In the latter case, the adsorbent can be removed from the first stream, for example, by filtration.

[0096] In this invention, washing step a) may include one or more of the following washing step sequence:

[0097] 1) The pickling step as described above, followed by the alkaline washing step as described above, optionally followed by the neutral washing step (or rinsing step) as described above;

[0098] 2) The pickling step as described above, optionally followed by the neutral washing step as described above, followed by the alkaline washing step as described above, optionally followed by the neutral washing step as described above;

[0099] 3) An alkaline washing step at a relatively low pH as described above, followed by an alkaline washing step at a relatively high pH as described above, optionally followed by a neutral washing step as described above, followed by an acid washing step as described above, optionally followed by a neutral washing step as described above.

[0100] Step b) — Extraction with extraction solvent b)

[0101] In step b) of the method of the present invention, at least a portion of the second stream produced by step a), comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons (by removing portions of the heteroatom-containing organic compounds and any other contaminants from the stream by contacting at least a portion of the stream with washing solvent a) in the preceding step a), is contacted with an extraction solvent b) containing one or more heteroatoms, and the stream is subjected to liquid-liquid extraction with extraction solvent b), thereby producing a first stream comprising aliphatic hydrocarbons and optionally heteroatom-containing organic compounds and a second stream comprising extraction solvent b), heteroatom-containing organic compounds, and optionally aromatic hydrocarbons.

[0102] In step b) of the method of the present invention, the second feed stream generated in step a) may be fed into the column (extraction column). Furthermore, the solvent stream containing the extraction solvent b) may be fed into the column at a higher position than the second feed stream generated in step a), thereby enabling countercurrent liquid-liquid extraction and producing a top stream from the first column (the "first stream") containing aliphatic hydrocarbons and optionally heteroatom-containing organic compounds, and a bottom stream from the column (the "second stream") containing the extraction solvent b), heteroatom-containing organic compounds, and optionally aromatic hydrocarbons.

[0103] In step b), the weight ratio of the extraction solvent b) to the second feed stream generated in step a) can be at least 0.05:1, or at least 0.2:1, or at least 0.5:1, or at least 1:1, or at least 2:1, or at least 3:1, and can be at most 5:1, or at most 3:1, or at most 2:1, or at most 1:1. Furthermore, the temperature in step b) can be at least 0°C, or at least 20°C, or at least 30°C, or at least 40°C, or at least 50°C, and can be at most 200°C, or at most 150°C, or at most 100°C, or at most 70°C, or at most 60°C, or at most 50°C, or at most 40°C. The pressure in step b) can be at least 100 bara, or at least 500 bara, or at least 1 bara, or at least 1.5 bara, or at least 2 bara, and can be at most 50 bara, or at most 30 bara, or at most 20 bara, or at most 15 bara, or at most 10 bara, or at most 5 bara, or at most 3 bara, or at most 2 bara, or at most 1.5 bara. The temperature and pressure in step b) are preferably such that both the hydrocarbons from the second feed stream generated in step a) and the extraction solvent b) are in a liquid state.

[0104] In step b), aliphatic hydrocarbons are recovered by liquid-liquid extraction of the heteroatom-containing organic compound and optionally aromatic hydrocarbons with extraction solvent b). Furthermore, preferably, the recovered aliphatic hydrocarbons comprise aliphatic hydrocarbons having a boiling point of 30°C to 300°C and aliphatic hydrocarbons having a boiling point above 300°C to 600°C, in a weight ratio of 99:1 to 1:99. The above description of the weight ratio of aliphatic hydrocarbons having a boiling point of 30°C to 300°C to aliphatic hydrocarbons having a boiling point above 300°C to 600°C in the liquid hydrocarbon feed stream also applies to the recovered aliphatic hydrocarbons.

[0105] In step b), the liquid-liquid extraction produces a first stream containing aliphatic hydrocarbons and optionally heteroatom-containing organic compounds, and a second stream containing extraction solvent b), heteroatom-containing organic compounds, and optionally aromatic hydrocarbons. Within this specification, the preceding stream (first stream) containing recovered aliphatic hydrocarbons may also be referred to as the "raffinate stream," and the subsequent stream (second stream) may also be referred to as the "extractant stream." The raffinate stream contains reduced amounts of aromatic hydrocarbons, conjugated aliphatic compounds having two or more carbon-carbon double bonds, and heteroatom-containing organic compounds. This raffinate stream contains no or at most 10% by weight, or at most 5% by weight, or at most 1% by weight of aromatic hydrocarbons, or substantially no aromatic hydrocarbons. Furthermore, this raffinate stream contains no or at most 15% by weight, or at most 10% by weight, or at most 5% by weight, or at most 1% by weight of conjugated aliphatic compounds having two or more carbon-carbon double bonds, or substantially no such aliphatic compounds. Furthermore, this raffinate stream contains no or at most 1% by weight of heteroatom-containing organic compounds, or substantially no such organic compounds.

[0106] The extraction solvent b) used in step b) of the method of the present invention (which can be fed as a solvent stream into the tower in step b) preferably has a density at least 3%, or at least 5%, or at least 8%, or at least 10%, or at least 15%, or at least 20% higher than the density of the second stream produced in step a). Furthermore, the density may be at most 50%, or at most 40%, or at most 35%, or at most 30% higher than the density of the second stream produced in step a).

[0107] Furthermore, the extraction solvent b) used in step b) contains one or more heteroatoms, which may be oxygen, nitrogen, and / or sulfur. More preferably, the extraction solvent b) is thermally stable at a temperature of 200°C. More preferably, the boiling point of the extraction solvent b) may be at least 50°C, or at least 80°C, or at least 100°C, or at least 120°C and at most 300°C, or at most 200°C, or at most 150°C. More preferably, the extraction solvent b) is miscible with or has relatively low miscibility in heptane. Preferably, the extraction solvent b) is miscible with heptane such that, based on the weight of heptane, at most 30% by weight, or at most 20% by weight, or at most 10% by weight, or at most 3% by weight, or at most 1% by weight of the extraction solvent b) is miscible with heptane. The miscibility of one compound in another compound (such as heptane) can be determined by any common method known to those skilled in the art (including ASTM Method D1476). When reference is made in this specification to the miscibility of one compound in another, it refers to miscibility at 25°C.

[0108] Furthermore, the distance R of the Hansen solubility parameter relative to heptane, measured at 25°C for the extraction solvent b) in step b) is... a，庚烷 It can be at least 3MPa 1 / 2 Preferably at least 5 MPa 1 / 2 More preferably at least 10 MPa 1 / 2 More preferably at least 15 MPa 1 / 2 Furthermore, the R of extraction solvent b) a，庚烷 Can be below 45MPa 1 / 2 or at most 40MPa 1 / 2 Preferably up to 35 MPa 1 / 2 More preferably up to 30 MPa 1 / 2 More preferably up to 25 MPa 1 / 2 For example, the R of N-methylpyrrolidone (NMP) a，庚烷 15MPa 1 / 2 .

[0109] Furthermore, the Hansen solubility parameter relative to heptane, measured at 25°C, of ​​the extraction solvent b) is at a distance R. a，庚烷 Distance R relative to Hansen solubility parameter of toluene a，甲苯 Differences (i.e., R) a，庚烷 -R a，甲苯 It can be at least 1.5 MPa 1 / 2 Preferably at least 2MPa 1 / 2 Furthermore, the R of the extraction solvent b) a，庚烷 With R a，甲苯 The difference can be up to 4.5 MPa. 1 / 2 Preferably at most 4MPa 1 / 2 .

[0110] The Hansen solubility parameter (HSP) can be used as a means to predict the similarity between one component and another. More specifically, each component is characterized by three Hansen parameters, each typically expressed in MPa. 0.5 Representation: δ d δ represents the energy of the dispersive forces between molecules; p δ represents the energy of the dipole intermolecular forces between molecules; and δ h , representing the energy of the hydrogen bond between molecules. The affinity between compounds can be described using a multidimensional vector quantifying these solvent atom and molecule interactions, represented by the Hansen solubility parameter (HSP) distance R. a It is defined in formula (1):

[0111] (R a ) 2 =4(δ) d2 –δd1 ) 2 +(δ p2 –δ p1 ) 2 +(δ h2 –δ h1 ) 2 (1)

[0112] in

[0113] R a = Distance between compound 1 and compound 2 in HSP space (MPa) 0.5 )

[0114] δ d1 δ p1 δ h1 =Hansen (or equivalent) parameter of compound 1 (in MPa) 0.5 (in units)

[0115] δ d2 δ p2 δ h2 =Hansen (or equivalent) parameter of compound 2 (in MPa) 0.5 (in units)

[0116] Therefore, R is calculated relative to the compound to be recovered in a given solvent. a The smaller the value (i.e., the compound to be recovered is compound 1 and the solvent is compound 2, or vice versa), the higher the affinity of the solvent for the compound to be recovered.

[0117] Hansen solubility parameters for many solvents can be found in, for example, the following literature: Allan FM Barton, CRCHandbook of Solubility Parameters and Other Cohesion Parameters, 2nd edition, CRCpress 1991; Charles M. Hansen, Hansen Solubility Parameters: A User's Handbook, CRC press 2007.

[0118] Specifically, the extraction solvent b) used in step b) of the method of the present invention may contain ammonia or preferably one or more organic solvents selected from: glycols and triols, including any isomer of monoethylene glycol (MEG), monopropylene glycol (MPG), butanediol, and glycerol; ethylene glycol ethers, including oligoethylene glycol and its monoalkyl ethers, wherein the oligoethylene glycol includes diethylene glycol, triethylene glycol, and tetraethylene glycol, and the monoalkyl ether includes diethylene glycol ethyl ether; amides, including N-alkylpyrrolidones, wherein the alkyl group can contain 1 to 8 or 1 to 3 carbon atoms, and including formamide, dialkylformamide, and acetamide, as well as monoalkylformamide and acetamide, wherein the alkyl group can contain 1 to 8 or 1 to 3 carbon atoms, the N-alkylpyrrolidone includes N-methylpyrrolidone (NMP), and the dialkylformamide and acetamide and monoalkylformamide and acetamide include dimethylformamide, dimethylformamide, and acetamide. The compounds include: methylformamide (DMF), methylformamide, and dimethylacetamide; dialkyl sulfoxides, wherein the alkyl group may contain 1 to 8 or 1 to 3 carbon atoms, the dialkyl sulfoxides including dimethyl sulfoxide (DMSO); sulfones, including sulfolane; N-formylmorpholine (NFM); furan ring-containing components and their derivatives, including furfural, 2-methyl-furan, furfuryl alcohol, and tetrahydrofurfuryl alcohol; hydroxy esters, including lactates, the lactates including methyl lactate and ethyl lactate; trialkyl phosphates, including triethyl phosphate; phenolic compounds, including phenol and guaiacol; benzyl alcohols, including benzyl alcohol; amines, including ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine; nitrile compounds, including acetonitrile and propionitrile; trioxane compounds, including 1,3,5-trioxane; carbonate compounds, including propylene carbonate and glyceryl carbonate; and cycloalkanone compounds, including dihydro-L-glucanone.

[0119] More preferably, the extraction solvent b) comprises one or more of the following: dialkyl sulfoxides, particularly DMSO; sulfones, particularly sulfolane; N-alkylpyrrolidones, particularly NMP; and a furan-ring-containing component, particularly furfural. Even more preferably, the extraction solvent b) comprises one or more of the above-mentioned N-alkylpyrrolidones (particularly NMP) and a furan-ring-containing component (particularly furfural). Most preferably, the extraction solvent b) comprises NMP.

[0120] Aqueous solutions of quaternary ammonium salts (especially trioctylmethylammonium chloride or methyltributylammonium chloride) can also be used as extraction solvents in step b).

[0121] As described above, the second feed stream generated by step b) for the first (extraction) column corresponds to the bottom feed stream from that column, containing extraction solvent b), heteroatom-containing organic compounds, and optionally aromatic hydrocarbons. In the presence of such compounds in the second feed stream generated by step a), the feed stream may also contain conjugated aliphatic compounds having two or more carbon-carbon double bonds.

[0122] In this invention, the extraction solvent b) can be recovered from the second stream generated by step b), and optionally from the first stream generated by step b) if it also contains the extraction solvent b), and then advantageously recycled back to step b). Suitably, the extraction solvent can be recovered and recycled in any manner, for example, as described in WO2020212315 or in co-pending patent application number EP20202249.7 filed on October 16, 2020, the disclosure of which is incorporated herein by reference.

[0123] Advantageously, any aromatic hydrocarbons and conjugated aliphatic compounds having two or more carbon-carbon double bonds removed during the recovery of extraction solvent b) as described above can be blended with cracked gasoline and processed into fuel or used in the production of aromatic compounds. Similarly, heteroatom-containing organic compounds removed in such recovery can optionally be converted into fuel after hydrotreating to remove heteroatoms. Furthermore, said compounds removed in such recovery can be further separated into various fractions that can be used as solvents.

[0124] Optional adsorption steps (i), (ii), (iii), and (iv)

[0125] Optionally, in the method of the present invention, one or more of the following adsorption steps (i), (ii), (iii), and (iv) may be performed. Specifically, optionally:

[0126] (i) During step a), at least a portion of the liquid hydrocarbon feed stream is contacted with the adsorbent, and then the first and second streams are separated in step a); and / or

[0127] (ii) Between the preceding step a) and the following step a), at least a portion of the second stream generated in the preceding step a) is brought into contact with the adsorbing reagent; and / or

[0128] (iii) Between step a) and step b), at least a portion of the second stream generated in step a) is brought into contact with the adsorbent reagent; and / or

[0129] (iv) The first stream produced by step b) contains aliphatic hydrocarbons and heteroatom-containing organic compounds, and after step b), at least a portion of the stream is contacted with an adsorbing reagent.

[0130] In this invention, advantageously, an adsorption agent can be used in steps (i), (ii), (iii), and (iv) to remove heteroatom-containing organic compounds and optional aromatic hydrocarbons, as well as optional other contaminants (such as the aforementioned silicon-containing compounds and metals), which are present in the liquid hydrocarbon feed stream or may not be completely removed in extraction step b) but are entrained in the first feed stream containing aliphatic hydrocarbons to be recovered produced by step a), for example, due to the relatively high concentration of these contaminants in the liquid hydrocarbon feed stream. Through this adsorption, advantageously, a final purified hydrocarbon product of sufficiently high quality can be obtained, allowing it to be further processed, for example, fed into a steam cracker.

[0131] Furthermore, as described above, the heteroatom-containing organic compounds and optional other contaminants extracted in the second (extraction) stream produced by step b) containing extraction solvent b), heteroatom-containing organic compounds, and optional aromatic hydrocarbons can accumulate in any recycled extraction solvent b) stream entering step b). The heteroatom-containing organic compounds causing this accumulation can be the most polar components among all the heteroatom-containing organic compounds extracted in step b) of the method of the invention. In this case, advantageously, through an optional adsorption step (iv) following extraction step b) in the method of the invention, a relatively pure final hydrocarbon product, substantially free of heteroatom-containing organic compounds and optional other contaminants, can then be delivered and, for example, fed into a steam cracker. Furthermore, through washing step a), and through optional adsorption steps (i) during washing step a) and / or optional adsorption steps (ii) between multiple washing steps a) and / or optional adsorption steps (iii) after washing step a) and before extraction step b), portions of these heteroatom-containing organic compounds and other optional contaminants have already been removed from the feed stream prior to extraction step b), thereby preventing the aforementioned accumulation in any extraction solvent b) recirculated stream. This relatively pure extraction solvent b) stream can then advantageously be recycled to step b) and used to extract additional heteroatom-containing organic compounds and optional aromatic hydrocarbons from the fresh feed. Therefore, in this invention, it is advantageous to remove, in washing step a) prior to extraction step b), the aforementioned contaminants (including heteroatom-containing organic compounds and any other contaminants (including any salts)) that have accumulated or may have accumulated as described above, and concentrate them in the adsorption reagent used in the optional adsorption steps (i), (ii), (iii) and / or (iv), thereby preventing the accumulation of such contaminants in any recycled stream in the method of this invention and ultimately resulting in a relatively pure final hydrocarbon product.

[0132] Because of the optional combination of (i) the pre-washing step a) and (ii) the adsorption of reagents before and / or after the extraction step b), the need to apply other cumbersome methods to mitigate the accumulation of these contaminants is eliminated or significantly reduced in this invention. For example, the need to discharge a portion of any recycle stream (e.g., any recycle extraction solvent a) before recirculation is eliminated or significantly reduced, wherein (i) such discharge stream is discarded, resulting in the loss of extraction solvent, or (ii) the extraction solvent can be recovered from such discharge stream, for example, by distillation, which is cumbersome.

[0133] It is envisioned that the removal of heteroatom-containing organic compounds, optional aromatic hydrocarbons, and optional other contaminants by adsorption as described above can be applied in one or more of the optional adsorption steps (i), (ii), (iii), and (iv) described above in the method of the present invention.

[0134] Therefore, specifically, the above-described adhesion can be applied in the method of the present invention to one or more of the following optional adhesion steps (i), (ii), (iii), and (iv) corresponding to the above-described optional adhesion steps (i), (ii), (iii), and (iv), wherein:

[0135] (i) prior to separating the first and second streams in step a), removing portions of the heteroatom-containing organic compounds from the liquid hydrocarbon feed stream by contacting at least a portion of the liquid hydrocarbon feed stream with an adsorbent during step a), and feeding at least a portion of the treated stream produced in step (i) into step b); and / or

[0136] (ii) By contacting at least a portion of the second stream generated from the preceding step a) with an adsorption reagent, a portion of the organic compound containing heteroatoms is removed from the stream, and at least a portion of the treated stream generated from step (ii) is fed into the subsequent step a); and / or

[0137] (iii) By contacting at least a portion of the second stream generated in step a) with an adsorption reagent, a portion of the organic compound containing heteroatoms is removed from the stream, and at least a portion of the treated stream generated in step (iii) is fed into step b); and / or

[0138] (iv) The first stream generated by step b) contains aliphatic hydrocarbons and heteroatom-containing organic compounds, and the heteroatom-containing organic compounds are removed from the stream by contacting at least a portion of the stream with an adsorbent.

[0139] Preferably, if the adsorption step is performed in the method of the present invention, the adsorption described above is applied in one or more of steps (i), (iii), and (iv) in the method of the present invention. Furthermore, when adsorption step (iii) is applied, at least a portion of the second stream generated by the final step (a) in series can be brought into contact with the adsorption reagent.

[0140] When the method of the present invention includes a single adsorption step, such a single adsorption step is preferably adsorption step (iii) or (iv), most preferably adsorption step (iv). When the method of the present invention includes two adsorption steps, these adsorption steps are preferably adsorption steps (i) and (iii) or adsorption steps (i) and (iv), most preferably adsorption steps (i) and (iv).

[0141] By means of optional adsorption steps (i), (ii), (iii), and (iv), at least a portion of the contaminants, in addition to removal by extraction step b) of the method of the invention, will advantageously be concentrated in the adsorption reagent used in such adsorption steps, thereby enabling the delivery of a final hydrocarbon product of sufficient quality (purity). Optional adsorption steps (i), (ii), (iii), and (iv) enable the processing by the method of the invention of liquid hydrocarbon feed streams containing relatively large amounts of heteroatom-containing organic contaminants and optionally other contaminants. Furthermore, the accumulation of these contaminants in any extraction solvent b) recirculated feed stream entering step b) will advantageously not lead to the accumulation of these contaminants in the final hydrocarbon product of adsorption step (iv) of the method of the invention. Additionally, by means of adsorption steps (i), (ii), and (iii) of the method of the invention, wherein a portion of these contaminants has already been removed from the feed stream in a subsequent step prior to extraction step b), the aforementioned accumulation of these contaminants in any extraction solvent b) recirculated feed stream entering step b) is prevented. Therefore, the adsorbent retains the contaminants, which can eventually be regenerated or removed from the process and replaced by fresh adsorbent, thus continuing to provide the aforementioned advantages.

[0142] Furthermore, in this invention, a portion of the treated stream produced by optional adsorption steps (i), (ii), and (iii) of the method of the invention may be fed to extraction step b), while another portion may bypass step b). It is also conceivable that, not according to the claimed invention, the entire treated stream produced by steps (i), (ii), and (iii) may bypass step b). For example, such bypassing may be suitable if the quality of the treated stream is high enough that it already meets the specifications for steam cracker feed. Then, at least a portion of the treated stream may be appropriately fed directly into the steam cracker without the need for an extraction step.

[0143] Advantageously, the flexibility of the method of the present invention is increased by the optional combination of adsorption steps (i), (ii), (iii) and / or (iv) with washing step a) and (partial) bypassing of extraction step b) as described above, which enables the processing of a wide range of liquid hydrocarbon feedstocks with different qualities (different contaminants and / or different levels of contaminants).

[0144] In the adsorption steps (i), (ii), (iii) and (iv) described above, contact with the adsorption reagent can be performed in any manner known to those skilled in the art.

[0145] In the adsorption step (i), it is preferable that the adsorbent is present as a suspension containing adsorbent particles in step a). Such adsorbent particles can be added to the feed stream containing washing solvent a) to be added to step a). In the case of such a suspension, it is preferable to remove the adsorbent from the treated feed stream, for example by filtration, before separating the first and second feed streams in step a). Alternatively, when separating the first and second feed streams in step a), the adsorbent can be removed together with the first feed stream containing washing solvent a) and heteroatom-containing compounds by sedimentation or by applying different methods, such as by using a separator (such as a centrifuge or hydrocyclone).

[0146] Furthermore, in adsorption steps (ii), (iii), and (iv), the adsorption reagent may be present as a suspension containing adsorption reagent particles as described above for adsorption step (i), or it may be immobilized in a packed bed. Preferably, in adsorption steps (ii), (iii), and (iv), the adsorption reagent is immobilized in a packed bed.

[0147] In this invention, when using the above-described suspension, the relative amount of adsorbent reagent in adsorption steps (i), (ii), (iii), and (iv) can be based on the feed to be treated entering the adsorption step, and is from 0.01 wt% to 20 wt%, preferably from 0.1 wt% to 5 wt%, more preferably from 0.1 wt% to 1 wt%. Furthermore, when using the above-described packed bed in adsorption steps (ii), (iii), and (iv), the liquid hourly space velocity (LHSV) can be from 0.1 L / h to 50 L / h, preferably from 1 L / h to 10 L / h. A specific target LHSV can depend on many factors, such as temperature and contaminant concentration.

[0148] In this specification, adsorption refers to the process by which one substance (adsorption reagent) adsorbs or retains another substance through absorption, adsorption, or a combination of both. Preferably, the adsorption reagent used in this invention is one that preferentially adsorbs heteroatom-containing compounds, optionally aromatic hydrocarbons, and optionally other contaminants as described above. In particular, it is preferred that heteroatom-containing compounds, optionally aromatic hydrocarbons, and optionally other contaminants as described above are preferentially adsorbed compared to the aliphatic hydrocarbons to be recovered and compared to any extraction solvent and / or washing solvent as defined in this specification.

[0149] The adsorption reagents used in steps (i), (ii), (iii), and (iv) of the method of the present invention suitably have a porous structure consisting of micropores, mesopores, macropores, or combinations thereof. According to IUPAC nomenclature, a microporous structure has a diameter less than 2 nm. The pore size is angstrom (Å), and the mesoporous structure has a pore size of 2 nm to 50 nm (Å). to The pore size is greater than 50 nm, and the macropore structure has a pore size greater than 50 nm. The aperture.

[0150] The adsorption reagents applicable to the use in steps (i), (ii), (iii), and (iv) are not limited to the specific materials listed in this specification. Generally, any material characterized by a relatively high specific surface area, having a porous structure including micropores, mesopores, or macropores, or combinations thereof, being of natural or synthetic origin, of mineral or organic origin, having a treated or untreated surface, and being in any form, can be used in this invention. The specific surface area can be 1 m². 2 / g to 3000m 2 / g, preferably 50m 2 / g to 2000m 2 / g, more preferably 100m 2 / g to 1000m 2 Within the range of / g. The specific surface area can be at least 1m². 2 / g, or at least 10m 2 / g, or at least 50m 2 / g. Furthermore, it can be up to 3000m 2 / g, or at most 1000m 2 / g, or at most 500m 2 / g. Furthermore, the pore volume of the suitable adsorption reagent used in steps (i), (ii), (iii), and (iv) is at least 0.001 cm³. 3 / g, or at least 0.01cm 3 / g, or at least 0.1cm 3 / g, and at most 1cm 3 / g, or at most 3cm 3 / g, or at most 5cm 3 / g, or at most 10cm 3 / g. Suitable adsorption reagents used in steps (i), (ii), (iii) and (iv) satisfy two of the above characteristics, namely pore size and surface area, or pore size and pore volume, or surface area and pore volume.

[0151] The adsorption reagents conveniently used in steps (i), (ii), (iii), and (iv) of the method of the present invention can be synthetic or natural molecular sieves. Furthermore, the adsorption reagents conveniently used in steps (i), (ii), (iii), and (iv) of the method of the present invention can be molecular sieves of inorganic origin (such as metal oxides, wherein the metal is one or more of alkaline earth metals, transition metals, and post-transition metals (such as Al, Si, Zn, Mg, Ti, Zr), or zeolites, clays, activated clays, alumina, activated alumina, amorphous alumina, silica gel, diatomaceous earth, magnesium silicate, aluminum silicate, amorphous silica, porous glass, etc.); or molecular sieves of organic origin (such as activated carbon, cross-linked and porous polymers, carbonaceous materials such as charcoal (“charcoal” represents “wood charcoal”), graphene-based nanomaterials, and single-walled or multi-walled carbon nanotubes); or hybrid molecular sieves, such as metal-organic frameworks. The adsorbent can be dispersed in a porous amorphous inorganic or organic matrix (also known as a binder), which has channels and cavities that allow liquid to enter the adsorbent. Alternatively, the adsorbent can be used without a binder.

[0152] The adsorption agent used in steps (i), (ii), (iii), and (iv) of the method of the present invention may be one or more adsorption agents selected from the group consisting of bleached clay, hydrogel silica, silicates, and activated carbon. Bleached clay is particularly preferred.

[0153] Bleaching clay minerals are hydrous foliated silicates, which may contain variable amounts of aluminum, iron, magnesium, alkali metals, alkaline earth metals, and other cations. Foliated silicates may include the following mineral subclasses: serpentine, clay minerals, mica, and chlorite.

[0154] Preferably, the adsorbent suitable for use in this invention is a foliated silicate derived from serpentine-kaolinite, talc-pyrophyllite, montmorillonite, vermiculite or illite, and / or mica. Serpentine-based foliated silicates may include pyrophyllite, fibrous serpentine, and limonite. Kaolinite-based foliated silicates may include halloysite, kaolinite, illite, montmorillonite, vermiculite, talc, sepiolite, palygorskite (or chloropalay), and pyrophyllite. Mica-based foliated silicates may include biotite, chromite, muscovite, phlogopite, lepidolite, pearlite, and glauconite. Chlorite-based foliated silicates may include chlorite.

[0155] More preferably, suitable adsorbents for use in this invention include highly active clays of the montmorillonite class, such as bentonite, which may primarily comprise montmorillonite or sepiolite, and which can be applied after acid activation; natural actives, also known as bleaching clays; and surface-modified adsorbents that can be activated "in situ" by adding acid, such as fiberstone, palygorskite (or palygorskite), and sepiolite. These clays may also contain other minerals such as calcium carbonate, quartz, and feldspar. Suitable examples of commercially available bleaching clays are the F-series and Nevergreen from BASF; the Pure-Flo and Perform series from Oil-Dri Corp.; the CynerSorb series from Imerys; and the Tonsil series from Clariant.

[0156] Other materials that can be used as suitable adsorbents in steps (i), (ii), (iii), and (iv) of this invention are hydrated layered alkali metal silicates. These materials can be natural or synthetic and include a negatively charged SiO2 layer (sheet), an alkaline cation for charge compensation, and in some cases, water between these layers. Examples of hydrated layered silicates are hydrated sodium silicate, octosilicate, magdiite, and hydrated sodium silicate. Furthermore, hydrated layered alkali metal silicates can be functionalized to produce inorganic-organic hybrids with adsorption purposes. Hydrated layered alkali metal silicates are preferably used for the removal of metal ions due to their high cation exchange capacity. Ion exchange resins also have the ability to replace inorganic acids when used as catalysts, and to remove contaminants such as metals and heteroatom-containing compounds, including phenols, aldehydes, and organic acids. For example, they have been used to remove fatty acids from oils. A commercially available ion exchange resin is Amberlite from Dow-DuPont. TMThese ion exchange resins include Amberlyst A23 (for acid removal), Amberlite XAD4 (for phenol removal), and the Amberlyst series (for replacing inorganic acids in the reaction). Such ion exchange resins can also be suitably used as adsorption reagents in this invention.

[0157] The clay or layered silicate adsorbents suitable for steps (i), (ii), (iii), and (iv) of this invention can be characterized by their pore volume, surface area, ion exchange capacity (IEC), and pore size distribution. The clay or layered silicate adsorbents suitable for this invention have a pore volume of at least 0.1 cm³. 3 / g, more preferably greater than 0.4cm 3 / g, preferably greater than 0.5cm 3 / g. The pore volume is preferably at most 1.0 cm³. 3 / g, more preferably up to 0.8cm 3 / g, most preferably at most 0.7cm 3 / g. The surface area of ​​the clay or layered silicate suitable for this invention is preferably 100m². 2 / g to 500m 2 / g, more preferably 200m 2 / g to 400m 2 The ion exchange capacity (IEC) of suitable layered silicates for use in this invention is at least 25 meq / 100g, but preferably higher than 40 meq / 100g, and most preferably in the range of 50 meq / 100g to 80 meq / 100g. The ion exchange capacity of synthesized layered silicates can be as high as 500 meq / 100g. Clay or layered silicates suitable for use in this invention are characterized by having a pore size distribution, such that preferably at least 20%, more preferably at least 22%, and most preferably at least 30% of the total pore volume is provided by pores with a diameter of at most 7.5 nm. Preferably at least 40%, more preferably at least 45%, and most preferably at least 50% of the total pore volume is provided by pores with a diameter of at most 14 nm. Preferably less than 40%, more preferably less than 35% of the total pore volume is provided by pores with a diameter greater than 25 nm.

[0158] Furthermore, the adsorbent used in steps (i), (ii), (iii), and (iv) of the present invention may be a combination of adsorbents disclosed in this specification. An example of a clay combination is a palygorskite / montmorillonite mixture containing preferably 10% to 90% by weight of palygorskite, more preferably 20% to 60% by weight of palygorskite, and most preferably 30% to 50% by weight of palygorskite.

[0159] As is known to those skilled in the art, the aforementioned inorganic adsorbent may first require treatment or activation (thermally or chemically) in order to optimally remove contaminants in steps (i), (ii), (iii), and (iv).

[0160] The carbon-containing adsorbents (such as activated carbon and coke) applicable to steps (i), (ii), (iii) and (iv) of the present invention may be composed primarily of carbon, for example, containing 80% to 100% by weight of carbon, preferably 90% to 100% by weight of carbon, more preferably 95% to 100% by weight of carbon, most preferably 98% to 100% by weight of carbon, and highly preferably 99% to 100% by weight of carbon.

[0161] In steps (i), (ii), (iii), and (iv), the preferred activated carbon used as the adsorbent for removing one or more of the aforementioned contaminants (including heteroatom-containing organic compounds) is derived from pitch. Furthermore, activated carbon suitable for use as such an adsorbent is preferably characterized by having an iodine value in the range of 500 mg / g to 1200 mg / g; and a high molasses value in the range of 95 to 1500, and preferably 200 to 1500. "Iodine value" is a relative measure of pores with a size of 10 angstroms to 28 angstroms. It is expressed as milligrams of elemental iodine adsorbed per gram of granular activated carbon and determines the area on the activated carbon available for adsorbing low molecular weight organic compounds. The iodine value can be determined according to ASTM D4607. "Molasses value" measures the degree to which activated carbon removes color from the original solution. It measures pores larger than 28 angstroms. These pores are responsible for removing higher molecular weight organic compounds. In this case, the amount of molasses adsorbed is quantified.

[0162] Furthermore, suitable activated carbon for use in this invention has a 600m 2 / g to 2000m 2 The total specific surface area is in the range of / g and the total pore volume is in the range of 0.9 mL / g to 2.5 mL / g. Furthermore, for pores greater than 20 angstroms, the preferred activated carbon used in this invention has a pore size exceeding 100 m² / g. 2 A specific surface area of ​​ / g and a pore volume exceeding 0.5 mL / g. These properties facilitate the removal of relatively large molecules, including the heteroatom-containing organic compounds and optional aromatic hydrocarbons to be removed in steps (i), (ii), (iii), and (iv).

[0163] Surface-modified and / or functionalized activated carbon and coke may also be suitably used in steps (i), (ii), (iii), and (iv). Suitable methods for generating functional properties on the surface of carbon materials include: oxidation by liquid and gaseous oxidants, grafting functional groups onto the material surface, physical adsorption of ligands, vapor deposition, and / or functional groups formed during carbon activation.

[0164] Suitable adsorbents used in steps (ii), (iii), and (iv) of this invention may be molecular sieves, which are zeolite-based, silica gel, alumina-based, clay-based, or activated carbon-based.

[0165] In this invention, the subgroup of heteroatom-containing organic compounds to be removed in adsorption steps (ii), (iii), and (iv) may include organochlorides, which may be polar or nonpolar. Adsorption reagents containing zeolites are suitable for removing such organochlorides. Specifically, adsorption reagents containing zeolites, including octahedral zeolite (FAU) frameworks such as X and Y, dealubilized zeolite Y, low-sodium ultrastable zeolite Y (USY); MFI type, such as ZSM-5 and Pentasil zeolite; MWW type, such as MCM-22, ITQ-1, and SSZ-25; BEA type, such as zeolite β; and mordenite (MOR) type, are suitable as adsorption reagents of this invention, particularly for the removal of organochlorides. Furthermore, the zeolite component of the adsorption reagent may be impregnated with metal cations derived from alkali metals, alkaline earth metals, transition metals, or post-transition metals defined in the periodic table. Because organochlorides can release chlorides in the form of hydrochloric acid after interacting with zeolite-based adsorbents, the adsorbent may also need to be provided with a basic or amphoteric oxide, such as alkali metal or alkaline earth metal oxides, hydroxides or carbonates, or activated alumina or another metal oxide, capable of capturing the released hydrochloric acid. Examples of commercially available zeolite-based materials suitable for this invention are adsorbent PCL-100 from UOP, adsorbent CL-850 from BASF, and adsorbent TCR-16 from UniCat.

[0166] Furthermore, in this invention, another subgroup of heteroatom-containing organic compounds to be removed in adsorption steps (ii), (iii), and (iv) may contain polar components. Adsorption reagents containing silica gel are suitable for removing such polar components. A suitable example of commercially available silica gel for removing polar components is from Grace Materials Technologies. In addition, suitable adsorbents for preferentially adsorbing polar components (including the aforementioned organochlorides) include zeolite-based materials having polarity determined by their Si / Al ratio, or zeolites that have been treated (such as cation exchange or surface modification) to increase their affinity for heteroatom-containing compounds and preferentially polar compounds.

[0167] In this invention, potential contaminants that must be removed by adsorption reagents can be the aforementioned silicon-containing compounds, such as silicon dioxide and siloxane compounds. Preferably, the reagents include silica gel, zeolite 13X, activated alumina, and hydrotalcite (general formula Mg6Al2CO3(OH)). 16 Layered binary hydroxide clay (H2O) and activated carbon adsorption agents are suitable for removing such silicon-containing compounds.

[0168] The temperature in steps (ii), (iii), and (iv) can be in the range of ambient temperature to about 400°C, preferably 40°C to 200°C, and more preferably 40°C to 180°C. Furthermore, the pressure in steps (ii), (iii), and (iv) can be in the range of atmospheric pressure to 100 bar, preferably 5 bar to 30 bar, and most preferably 5 bar to 20 bar. This pressure may differ from the pressure in washing step a) (which may include the pressure in adsorption step (i)) and extraction step b).

[0169] Heteroatom-containing compounds and optional aromatic hydrocarbons accumulate in the adsorbent material, resulting in "waste adsorbent." As is known in the art, the adsorbent eventually needs to be replaced or regenerated. In either case, the corresponding container containing the waste adsorbent will be taken out of service. In the case of regeneration, the waste adsorbent is brought into contact with a feed stream that does not contain heteroatom-containing compounds and optional aromatic hydrocarbons. Preferably, the feed stream is heated to promote the desorption of heteroatom-containing compounds and optional aromatic hydrocarbons. The regeneration feed stream can be a gas, liquid, or supercritical fluid. It can be inert, such as nitrogen, or reactive, such as hydrogen, oxygen, and hydrogen peroxide. Depending on the regeneration method, the regeneration temperature ranges from 20°C to 350°C. The adsorbent material can be regenerated by stripping the feed stream with a gas stream such as steam or nitrogen, or by heating the adsorbent in air to burn off the adsorbed material. Alternatively, in cases where the adsorbent material used in this invention cannot be completely regenerated, it must be discarded when its adsorption capacity is reached. Furthermore, regarding the adsorbent used in step a), when the adsorbent is separated as waste adsorbent, the organic compounds contained in the adsorbent can be removed by washing the adsorbent with organic solvents known in the art. Alternatively, the adsorbent is removed for disposal such as incineration.

[0170] Upstream and downstream integration

[0171] In this invention, the liquid hydrocarbon feedstock stream may contain at least a portion of hydrocarbon products formed in a method comprising cracked plastics, preferably waste plastics, more preferably mixed waste plastics, wherein at least a portion of these plastics contains heteroatom-containing organic compounds.

[0172] Therefore, the present invention also relates to a method for recovering aliphatic hydrocarbons from plastics, wherein at least a portion of these plastics contains heteroatom-containing organic compounds, the method comprising the following steps:

[0173] (I) Cracking the plastic and recovering hydrocarbon products, said hydrocarbon products comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons; and

[0174] (II) Perform the above-described method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feed stream, the liquid hydrocarbon feed stream comprising at least a portion of the hydrocarbon products obtained in step (I).

[0175] The preferred requirements and embodiments described above with reference to the aliphatic hydrocarbon recovery method of the present invention also apply to step (II) of the method of the present invention for recovering aliphatic hydrocarbons from plastics. In step (I) above, the resulting hydrocarbon product can be a liquid, or a solid or wax. In the latter case, the solid or wax is first heated to liquefy it, and then subjected to the aliphatic hydrocarbon recovery method in step (II).

[0176] In the above method, at least a portion of the plastic fed into step (I) comprises heteroatom-containing organic compounds, preferably waste plastics, more preferably mixed waste plastics. In step (I), the cracking of the plastic may involve a thermal cracking process and / or a catalytic cracking process. The cracking temperature in step (I) may be from 300°C to 800°C, suitably from 400°C to 800°C, more preferably from 400°C to 700°C, and even more preferably from 500°C to 600°C. Furthermore, any pressure may be applied, which may be below atmospheric pressure, atmospheric pressure, or above atmospheric pressure. The heat treatment in step (I) causes the plastic to melt and its molecules to crack into smaller molecules. The cracking in step (I) may be carried out as pyrolysis or as liquefaction. A continuous liquid phase is formed in both pyrolysis and liquefaction. In addition, a discontinuous gas phase is formed in pyrolysis, which escapes from the liquid phase and separates into a continuous gas phase. In liquefaction, because relatively high pressure is applied, there is no significant gas phase.

[0177] Furthermore, in step (I), subsequent gas-phase condensation and / or liquid-phase cooling provide a hydrocarbon product, which may be liquid, solid, or wax, and contains aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons, and in step (II), at least a portion of the hydrocarbon product is subjected to the above-described aliphatic hydrocarbon recovery method.

[0178] The above steps (I) may be performed in any known manner, such as as disclosed in WO2018069794 or WO2017168165, the contents of which are incorporated herein by reference.

[0179] Advantageously, in one of the methods described above for recovering aliphatic hydrocarbons, the recovered aliphatic hydrocarbons (which may include varying amounts of aliphatic hydrocarbons over a wide boiling point range) can be fed into a steam cracker without further pretreatment (such as hydrogenation or hydrotreating). In addition to being used as feed to a steam cracker, the recovered aliphatic hydrocarbons can also advantageously be fed into other refining processes, including hydrocracking, isomerization, hydrotreating, thermocatalytic cracking, and fluidized catalytic cracking. Furthermore, besides being used as feed to a steam cracker, the recovered aliphatic hydrocarbons can also advantageously be separated into different fractions, each with different applications, such as diesel fuel, marine fuel, solvents, etc.

[0180] Therefore, the present invention also relates to a method for steam cracking hydrocarbon feedstock, wherein the hydrocarbon feedstock contains aliphatic hydrocarbons recovered in one of the methods described above for recovering aliphatic hydrocarbons. Furthermore, the present invention also relates to a method for steam cracking hydrocarbon feedstock, the method comprising the steps of: recovering aliphatic hydrocarbons from a liquid hydrocarbon feedstock stream in one of the methods described above for recovering aliphatic hydrocarbons; and steam cracking a hydrocarbon feedstock containing the aliphatic hydrocarbons recovered in the preceding step. In this specification, the phrase "hydrocarbon feedstock containing aliphatic hydrocarbons recovered in the preceding step" can refer to "hydrocarbon feedstock containing at least a portion of the recovered aliphatic hydrocarbons." In addition to the method for recovering aliphatic hydrocarbons of the present invention, the hydrocarbon feedstock of the steam cracking process may also contain hydrocarbons from another source. This other source may be naphtha, wax oil, or a combination thereof.

[0181] Advantageously, in cases where the liquid hydrocarbon feed stream contains aromatic hydrocarbons (especially polycyclic aromatic compounds), heteroatom-containing organic compounds, conjugated aliphatic compounds having two or more carbon-carbon double bonds, or combinations thereof, these contained compounds have been removed by the aliphatic hydrocarbon recovery method of the present invention as described above before the recovered hydrocarbon feed is introduced into the steam cracking process. This is particularly advantageous because the removed compounds (especially polycyclic aromatic compounds) will no longer cause scaling in the preheating, convection, and radiation sections of the steam cracker, as well as in the downstream heat exchange and / or separation equipment of the steam cracker (e.g., in the transfer line exchanger (TLE) used for rapid cooling of the effluent from the steam cracker). When hydrocarbons condense, they can thermally decompose into a coke layer that can cause scaling. This scaling is a major factor determining the operating time of the cracker. Reducing scaling extends operating time without maintenance downtime and improves heat transfer in the heat exchanger.

[0182] Steam cracking can be carried out in any known manner. The hydrocarbon feedstock is typically preheated. The feedstock can be heated using a heat exchanger, furnace, or any other combination of heat transfer and / or heating equipment. The feedstock is steam cracked in a cracking zone under cracking conditions to produce at least olefins (including ethylene) and hydrogen. The cracking zone may include any cracking system known in the art suitable for cracking feedstocks. The cracking zone may include one or more furnaces, each dedicated to a specific feedstock or a fraction of the feedstock.

[0183] Cracking is carried out at elevated temperatures, preferably between 650°C and 1000°C, more preferably between 700°C and 900°C, and most preferably between 750°C and 850°C. Steam is typically added to the cracking zone to act as a diluent, reducing hydrocarbon partial pressure and thereby increasing olefin yield. Steam also reduces the formation and deposition of carbonaceous material or coke in the cracking zone. Cracking occurs in the absence of oxygen. Residence times under cracking conditions are very short, typically on the order of milliseconds.

[0184] The cracker effluent obtained from the cracker may contain aromatic compounds (such as those produced during steam cracking), olefins, hydrogen, water, carbon dioxide, and other hydrocarbon compounds. The specific products obtained depend on the feed composition, the hydrocarbon-to-steam ratio, the cracking temperature, and the residence time in the furnace. The cracking products from the steam cracker are then passed through one or more heat exchangers (commonly referred to as TLEs (“online heat exchangers”)) to rapidly reduce the temperature of the cracking products. The TLEs preferably cool the cracking products to a temperature in the range of 400°C to 550°C.

[0185] Attached Figure

[0186] Figure 1 and Figure 2 The present invention further illustrates the method for recovering aliphatic hydrocarbons from a liquid hydrocarbon feedstock stream.

[0187] exist Figure 1 In the method, a liquid hydrocarbon feed stream 1 containing aliphatic hydrocarbons (including conjugated aliphatic compounds having two or more carbon-carbon double bonds, hereinafter referred to as "dienes"), aromatic hydrocarbons, heteroatom-containing organic compounds, and salts, and a feed stream 10 containing water (which serves as a washing solvent a according to the invention) and having a pH below 7 (acid) are fed into a mixer 11 and mixed therein. Furthermore, as in... Figure 1 The label “(X)” indicates that the adsorption reagent can be fed into the mixer 11, which represents the optional adsorption step (i) according to the invention.

[0188] The resulting mixed stream 12 is fed to decanter 20. In decanter 20, the mixed stream is separated into stream 21 containing aliphatic hydrocarbons, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds, and stream 22 containing water, heteroatom-containing compounds, and salts. Stream 22 is separated into streams 22a and 22b, wherein stream 22b is optionally recycled to mixer 11 after the organic compounds and salts are removed from it. Stream 21 and stream 10' containing water as washing solvent a) according to the invention and having a pH higher than 7 (alkaline) are fed to mixer 11' and mixed therein. Figure 1 The symbol “(X)” indicates that the feed stream 21 can come into contact with the adsorption reagent, which represents the optional adsorption step (ii) according to the invention. Furthermore, as in Figure 1 The label “(X)” indicates that the adsorption reagent can be fed into the mixer 11', which represents the optional adsorption step (i) according to the invention.

[0189] The resulting mixed stream 12' is fed to decanter 20'. In decanter 20', the mixed stream is separated into stream 21' containing aliphatic hydrocarbons, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds, and stream 22' containing water, heteroatom-containing compounds, and salts. Stream 22' is separated into stream 22a' and stream 22b', wherein stream 22b' is optionally recycled to mixer 11' after removing organic compounds and salts from stream 22b'. Stream 21' and stream 23 containing water as washing solvent a) according to the invention and having a pH of about 7 are fed to extraction column 24. Furthermore, as in Figure 1 The symbol “(X)” indicates that stream 21' can be contacted with the adsorbent, representing the optional adsorption step (ii) according to the invention. In column 24, stream 21' is contacted with stream 23 (water) to perform liquid-liquid extraction of heteroatom-containing organic compounds with water, resulting in a top stream 25 containing aliphatic hydrocarbons, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds, and a bottom stream 26 containing water and heteroatom-containing compounds. Stream 26 can be combined with a portion of stream 22 from decanter 20. Furthermore, as in… Figure 1 The symbol “(X)” indicates that the feed stream 25 can come into contact with the adsorption reagent, which represents the optional adsorption step (iii) according to the invention.

[0190] In addition, Figure 1In the method, the following streams are fed into extraction column 4: stream 25 from extraction column 24; a first solvent stream 2 containing an organic solvent (e.g., N-methylpyrrolidone), wherein the organic solvent serves as extraction solvent b according to the invention; and a second solvent stream 3 containing water as a washing solvent. In column 4, stream 25 is contacted with the first solvent stream 2 (organic solvent) to recover aliphatic hydrocarbons by liquid-liquid extraction of dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds with the organic solvent. Furthermore, the water in the second solvent stream 3 is used to remove the organic solvent from the top of column 4 by liquid-liquid extraction of the organic solvent with water. Stream 5 containing the recovered aliphatic hydrocarbons exits column 4 at the top. Furthermore, stream 6 containing the organic solvent, water, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds exits column 4 at the bottom. Figure 1 The symbol “(X)” indicates that stream 5 can be contacted with the adsorbent reagent, representing the optional adsorption step (iv) according to the invention. Stream 6 and stream 14, which contains additional water (as a separating solvent), are combined, and the combined streams are fed to decanter 13. In decanter 13, the combined streams are separated into stream 15, which contains dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds, and stream 16, which contains organic solvent, water, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds. Stream 16 is fed to distillation column 7, where it is separated into overhead stream 8, which contains water, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds, and bottom stream 9, which contains organic solvent. The organic solvent from bottom stream 9 is recycled via organic solvent stream 2. Feed stream 8 is fed to the top decanter 17, where it is separated into a stream 18 containing dienes, aromatic hydrocarbons and heteroatom-containing organic compounds and a stream containing water. The water stream may also contain relatively small amounts of dienes, aromatic hydrocarbons and heteroatom-containing organic compounds. A portion of the water stream (stream 19a) is returned to the distillation column 7 as a reflux stream, while another portion (stream 19b) may be recycled via water stream 14 and / or water stream 3 and / or water stream 10 and / or water stream 23.

[0191] exist Figure 2 In this method, the aforementioned liquid hydrocarbon feedstock 1 is first contacted with water (which serves as the washing solvent a according to the invention), first in mixer 11 and decanter 20, then in mixer 11' and decanter 20', and subsequently in extraction column 24. Regarding Figure 2 This upstream processing of the raw material stream in the method, for Figure 1 Referring to the above description of the corresponding treatment in the method, it also includes optionally contact with an adsorption reagent, such as in Figure 2The symbols “(X)” indicate the adsorption steps (i), (ii) and (iii) according to the invention, in combination with mixers 11 and 11', feed streams 21 and 21' and feed stream 25.

[0192] In addition, Figure 2 In the method, the following feed streams are fed into a first extraction column 4a: a feed stream 25 from extraction column 24, comprising aliphatic hydrocarbons, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds; and a first solvent feed stream 2 comprising an organic solvent (e.g., N-methylpyrrolidone), wherein the organic solvent serves as the extraction solvent b according to the invention. In column 4a, feed stream 25 is contacted with the first solvent feed stream 2 (organic solvent) to recover aliphatic hydrocarbons by liquid-liquid extraction of dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds with the organic solvent, thereby producing a top feed stream 5a comprising the recovered aliphatic hydrocarbons and the organic solvent, and a bottom feed stream 6 comprising the organic solvent, dienes, aromatic hydrocarbons, and heteroatom-containing organic compounds. Feed stream 5a and a second solvent feed stream 3 comprising water (as a washing solvent) are fed into a second extraction column 4b. In column 4b, feed stream 5a is contacted with the second solvent feed stream 3 (water) to remove the organic solvent by liquid-liquid extraction of the organic solvent with water. Stream 5b, containing recovered aliphatic hydrocarbons, exits column 4b at the top. Additionally, stream 14, containing organic solvent and water, exits column 4b at the bottom; the water is a phased solvent. (As in...) Figure 2 The symbol “(X)” indicates that feed stream 5b can be brought into contact with the adsorption reagent, representing the optional adsorption step (iv) according to the invention. Feed streams 6 and 14 are combined, and the combined feed stream is fed into decanter 13. Regarding the processing in decanter 13 and... Figure 2 For further downstream processing in the method, please refer to the above text. Figure 1 The description of the corresponding processing in the method.

Claims

1. A method for recovering aliphatic hydrocarbons from plastics, wherein at least a portion of the plastics comprises heteroatom-containing organic compounds, the method comprising the following steps: (I) Cracking the plastic and recovering hydrocarbon products, said hydrocarbon products comprising aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons; and (II) subjecting a liquid hydrocarbon feed stream to the following steps, the liquid hydrocarbon feed stream comprising at least a portion of the hydrocarbon product obtained in step (I), and comprising at least 20% by weight of an olefinic aliphatic compound: a) Mixing at least a portion of the liquid hydrocarbon feed stream with a stream containing a washing solvent a) having a pH higher than 7 and containing one or more heteroatoms, and separating the resulting mixture into a first stream containing the washing solvent a) and a heteroatom-containing compound, and a second stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds, and optionally aromatic hydrocarbons. Step a) further includes: a1) Before mixing with the feed stream having a pH higher than 7: mixing at least a portion of the liquid hydrocarbon feed stream with a feed stream having a pH lower than 7 and containing a washing solvent a) containing one or more heteroatoms, and separating the resulting mixture into a first feed stream containing washing solvent a) and a heteroatom-containing compound and a second feed stream containing aliphatic hydrocarbons, heteroatom-containing organic compounds and optionally aromatic hydrocarbons, and mixing at least a portion of the second feed stream with the feed stream having a pH higher than 7; and b) Contacting at least a portion of the second stream produced in step a) with an extraction solvent b) containing one or more heteroatoms, and performing liquid-liquid extraction of the stream with the extraction solvent b) to produce a first stream containing aliphatic hydrocarbons and optionally heteroatom-containing organic compounds and a second stream containing extraction solvent b), heteroatom-containing organic compounds and optionally aromatic hydrocarbons.

2. The method according to claim 1, wherein: The washing solvent a) has a strength of at least 10 MPa. 1 / 2 R a，庚烷 , where R a，庚烷 This refers to the Hansen solubility parameter distance relative to heptane, measured at 25°C; and The washing solvent a) has a sodium chloride solubility of at least 0.1 g / 100 g, measured at 25 °C, based on the number of grams of NaCl in each 100 g of solvent.

3. The method according to claim 2, wherein the washing solvent a) has a strength of at least 15 MPa. 1 / 2 R a，庚烷 .

4. The method according to claim 2, wherein the washing solvent a) has a sodium chloride solubility of at least 1 g / 100 g, measured at 25°C, based on the number of grams of NaCl in each 100 g of solvent.

5. The method according to any one of claims 1 to 4, wherein the washing solvent a) comprises one or more solvents selected from the group consisting of water, ammonia, and organic solvents, wherein the organic solvents are selected from the group consisting of diols and triols.

6. The method according to claim 5, wherein the organic solvent comprises ethylene glycol (MEG), propylene glycol (MPG), and glycerol.

7. The method of claim 5, wherein the washing solvent a) comprises water.

8. The method according to any one of claims 1 to 4, wherein: The extraction solvent b) has a strength of at least 5 MPa. 1 / 2 R a，庚烷 , where R a，庚烷 This refers to the Hansen solubility parameter distance relative to heptane, measured at 25°C.

9. The method according to claim 8, wherein the extraction solvent b) has a strength of at least 10 MPa. 1 / 2 R a，庚烷 .

10. The method according to any one of claims 1 to 4, wherein the extraction solvent b) comprises an amide.

11. The method of claim 10, wherein the amide comprises N-alkylpyrrolidone, wherein the alkyl group contains 1 to 8 carbon atoms.

12. The method of claim 10, wherein the amide comprises N-alkylpyrrolidone, wherein the alkyl group contains 1 to 3 carbon atoms.

13. The method of claim 11, wherein the N-alkylpyrrolidone comprises N-methylpyrrolidone (NMP).

14. The method of claim 10, wherein the amide comprises formamide, dialkylformamide, dialkylacetamide, monoalkylformamide, and monoalkylacetamide, wherein the alkyl group contains 1 to 8 carbon atoms.

15. The method of claim 10, wherein the amide comprises formamide, dialkylformamide, dialkylacetamide, monoalkylformamide, and monoalkylacetamide, wherein the alkyl group contains 1 to 3 carbon atoms.

16. The method of claim 15, wherein the amide comprises dimethylformamide (DMF), methylformamide, and dimethylacetamide.

17. The method according to any one of claims 1 to 4, wherein: (i) During step a), at least a portion of the liquid hydrocarbon feed stream is contacted with an adsorbent, and then the first stream and the second stream are separated in step a); and / or (ii) Between the preceding step a) and the following step a), at least a portion of the second stream generated in the preceding step a) is brought into contact with the adsorbent; and / or (iii) Between step a) and step b), at least a portion of the second feed stream generated in step a) is brought into contact with the adsorbing reagent; and / or (iv) The first stream generated by step b) comprises aliphatic hydrocarbons and heteroatom-containing organic compounds, and after step b), at least a portion of the stream is contacted with an adsorption reagent.

18. The method of claim 17, wherein: (i) Prior to separating the first and second streams in step a), at least a portion of the liquid hydrocarbon feed stream is contacted with an adsorbent during step a) to remove portions of the heteroatom-containing organic compounds from the stream, and at least a portion of the treated stream produced in step (i) is fed into step b); and / or (ii) By contacting at least a portion of the second stream generated in the preceding step a) with an adsorption reagent, a portion of the heteroatom-containing organic compound is removed from the stream, and at least a portion of the treated stream generated in step (ii) is fed into the subsequent step a); and / or (iii) Removing a portion of the heteroatom-containing organic compound from the second stream generated in step a) by contacting at least a portion of the second stream with an adsorption reagent, and feeding at least a portion of the treated stream generated in step (iii) into step b); and / or (iv) The first stream generated by step b) contains aliphatic hydrocarbons and heteroatom-containing organic compounds, and the heteroatom-containing organic compounds are removed from the stream by contacting at least a portion of the stream with an adsorption reagent.

19. A method for steam cracking hydrocarbon feed, wherein the hydrocarbon feed comprises aliphatic hydrocarbons recovered in the method according to any one of claims 1 to 18.

20. A method for steam cracking hydrocarbon feedstock, the method comprising the following steps: Aliphatic hydrocarbons are recovered from a liquid hydrocarbon feedstock in any one of claims 1 to 18; as well as Steam cracking includes a hydrocarbon feedstock of aliphatic hydrocarbons recovered in the previous step.

Images