Method for treating a plastic liquefaction oil composition by gasification

Abstract

A method of purifying a composition comprising a plastic liquefaction oil, comprising treating the composition to reduce the content of heteroatoms by treatment with a basic compound followed by washing, separation or separation followed by washing. The composition thus treated is then subjected to a gasification process to produce syngas comprising at least dihydrogen, carbon monoxide and carbon dioxide.

Description

[0001] METHOD FOR TREATING A PLASTIC LIQUEFACTION OIL COMPOSITION BY GASIFICATION

[0002] Field of invention

[0003] The present invention relates to a process for the recovery by gasification of a composition comprising a plastic liquefaction oil. The process according to the invention makes it possible in particular to reduce the heteroatom concentration of the charges originating from plastic waste, with a view to their use in a gasification process.

[0004] State of the art

[0005] Plastic waste is most often sent to landfills or incinerated, with a smaller portion directed toward recycling. However, there is a significant need, encouraged by regulations, to limit plastic waste in landfills. On the other hand, disposing of plastic waste in landfills is becoming increasingly difficult. Therefore, it is necessary to recycle plastic waste.

[0006] One possible way to recycle plastic is to liquefy the plastic through pyrolysis or hydrothermal liquefaction. The resulting liquid can then be introduced into a gasification process to complete the plastic recycling process. However, the resulting plastic oil typically contains large amounts of dienes and heteroatoms, including chlorine. These many heteroatoms, especially chlorine, are contaminants in gasification processes. In addition, dienes react easily to form gums, and chlorine causes corrosion problems. Therefore, plastic liquefaction oils must be treated for recycling. There are many treatment processes available to reduce the heteroatom content of plastic liquefaction oils.

[0007] Patent application WO2020 / 020769 claims a series of processes for purifying a composition comprising at least 20 ppm of chlorine. Many recyclable liquid wastes can be treated, including plastic pyrolysis oils. The process sequence comprises a thermal treatment of the feedstock in the presence of an alkali metal hydroxide in order to obtain a reduction of at least 50% of the chlorine content relative to the feedstock, followed by hydrotreatment in order to obtain a further reduction of at least 50% of the chlorine content.

[0008] Patent application WO2021 / 105326 claims a method for the recovery of liquefied plastic waste comprising a step of pretreating the liquefied plastic waste by contacting it with an aqueous medium having a pH of at least 7 at a temperature of 200°C or higher, followed by a liquid-liquid separation in which the aqueous phase is separated from the organic phase, to produce a pretreated liquefied waste plastic material. The proposed solution comprises the use of a solution of NaOH in water. The separation of the aqueous and organic phases is carried out by physical (centrifugation) or chemical methods (addition of separation aid additives, e.g. non-aqueous solvents, addition of additional quantity of the aqueous medium used for contacting or of an aqueous medium having a different alkaline substance concentration), or by gravity.

[0009] Most existing purification treatments are carried out at relatively high temperatures. Due to the very high contaminant levels in plastic liquefaction oils, these treatments are not economically viable. Furthermore, gasification processes require a feedstock with a very low heteroatom content, particularly chlorine, to function properly and limit the risk of corrosion.

[0010] There is therefore a need for a less expensive method of treating plastic liquefaction oils before injection into a gasification process.

[0011] Summary of the invention

[0012] The invention aims to provide a method for treating plastic liquefaction oil by gasification, comprising a purification treatment. In particular, this purification treatment can be carried out at a relatively low temperature while maintaining high reduction performance in heteroatoms, and in particular in chlorine. The purification treatment also makes it possible to reduce the content of alkali and / or alkaline earth metals in the liquefaction oil already present and / or which have been introduced during the treatment of the plastic liquefaction oil with a basic compound containing, for example, an alkali or alkaline earth metal.

[0013] For this purpose, the invention relates to a method for treating by gasification a composition comprising a plastic liquefaction oil, comprising the following steps: a) providing a composition comprising a plastic liquefaction oil containing at least 20 ppm by mass of heteroatoms, in particular at least 20 ppm by mass of chlorine, b) bringing the composition provided in step a) into contact with a basic compound at a temperature of at most 450°C to obtain a first effluent containing a modified composition, c) subjecting the first effluent from step b) to (c1) washing with water or a solvent immiscible with the modified composition, (c2) separation, or to the succession of steps (c2) and (c1), and obtaining a second effluent containing a purified composition having a reduced content of heteroatoms, and a phase containing the basic compound and heteroatoms initially contained in the modified composition, d) optionally,the second effluent from step c) is separated by distillation into at least two distinct fractions, e) subjecting the second effluent from step c) or one of the fractions from step d), alone or in a mixture with another hydrocarbon feedstock, to a gasification process to produce synthesis gas comprising at least dihydrogen, carbon monoxide and carbon dioxide.,

[0014] Advantageously, prior to the treatment of step b), said composition may be subjected to (i) filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv).

[0015] Step b) according to the invention may comprise one or more of the following characteristics: step b) is carried out in the presence of 0.1 to 50% by weight of basic compound relative to the total mass of the composition treated, prior to step b) or during step b), there is added to the composition of step a) (i) a solid basic compound, (ii) a basic compound previously solubilized in an aqueous medium, preferably water, or (iii) a basic compound previously solubilized in a solvent, preferably a polar solvent immiscible with said composition, the basic compound comprises an oxide, a hydroxide, a bicarbonate or an alcoholate of an alkali metal cation or an alkaline-earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or as a mixture, preferably the basic compound comprises an oxide, a hydroxide, a bicarbonate of an alkali metal cation or of an alkaline earth metal cation,or a hydroxide or bicarbonate of a quaternary ammonium cation, alone or as a mixture, the basic compound may be chosen from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, TMAOH, TEAOH, TBuOH, MeONa, EtONa and mixtures thereof, preferably the basic compound may be chosen from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, TMAOH, TEAOH, TBuOH, and mixtures thereof, step b) is carried out at a temperature of 50 to 450 °C, preferably 50 to 350 °C, more preferably 50 to 250 °C, more preferably still from 50 to 225°C, from 50 to 200°C, from 70 to 190°C or from 80 to 185°C, or in any interval defined by any two of these limits, step b) of contacting is carried out for a period of 0.1 seconds to 3 hours, preferably from 0.1 seconds to 2 hours, more preferably from 1 minute to 1 hour, even more preferably from 1 minute to 20 minutes or from 1 minute to 16 minutes.,

[0016] Step c) according to the invention may comprise one or more of the following features: step c1) is carried out in the presence of water at neutral, basic or acidic pH, or in the presence of an organic solvent immiscible with the composition, preferably in the presence of water, step c2) is carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps, step c) comprises at least the separation step (c2) to separate the phase containing the basic compound and heteroatoms, and the purified composition, and the phase containing the basic compound and heteroatoms is returned in whole or in part to step b), step c) is preceded or followed, in particular immediately preceded or followed, by a step of separation of the solids by (i) filtration, (ii) centrifugation, (iii) hydrocyclone or (iv) a combination of two or more of these steps,step c) is followed by purification by passage over a solid adsorbent in order to reduce the content of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and / or the water content, optionally carried out before the optional separation step d), step c) is followed by catalytic hydrotreatment, namely catalytic treatment under hydrogen, in one or two stages to provide a purified hydrotreated composition, optionally carried out before the optional separation step d). The purified and hydrotreated composition thus obtained can further be washed with water to remove inorganic compounds such as hydrosulfide, hydrogen chloride, ammonia, before being sent to step d) or e).,

[0017] The synthesis gas produced during step e) can be (i) treated in a purification unit, (ii) treated in a Fischer-Tropsch process (in particular to produce paraffins), (iii) used as fuel (energy recovery, in particular by cogeneration), and / or (iv) used in an alcohol production unit by fermentation or catalytic route. These different units are well known. In particular, the purification units can be chosen in the usual manner depending on the objective and the gasification process used, in particular to remove any tar that may be present.

[0018] The previously described steps of the method according to the invention can be implemented one after the other without an intermediate step except for the optional additional steps described.

[0019] The invention also relates to an installation, in particular adapted to the implementation of the method according to the invention, comprising an optional pretreatment section (A), a treatment section (B), at least one optional solids separation section (S1, S2), a separation section (C), an optional hydrotreatment section (HDT), an optional distillation section (D) and a gasification section (E), in which the different sections are fluidically connected to implement the method according to the invention. Definitions

[0020] Hourly Volume Velocity (WH) is defined as the hourly volume of charge flow per unit of catalytic volume and is expressed here in h' 1 .

[0021] The terms "comprising" and "comprises" as used herein are synonymous with "including," "includes," or "contains," "containing," and are inclusive or unbounded and do not exclude additional features, elements, or method steps not specified.

[0022] The specification of a numeric domain without decimals includes all whole numbers and, where appropriate, fractions thereof (e.g., 1 to 5 may include 1, 2, 3, 4, and 5 when referring to a number of items, and may also include 1.5, 2, 2.75, and 3.80 when referring to, for example, a measure).

[0023] The specification of a decimal also includes the decimal itself (e.g., "from 1.0 to 5.0" includes 1.0 and 5.0). Any range of numeric values ​​recited here also includes any subrange of numeric values ​​mentioned above.

[0024] The expressions % by weight and % by mass (noted %m) have an equivalent meaning and refer to the proportion of the mass in grams of a product relative to 100 g of a composition comprising it.

[0025] Unless otherwise stated, measurements given in parts per million (ppm) are expressed by weight.

[0026] By "heteroatom" we mean any element of an organic compound other than carbon and hydrogen.

[0027] The expression "polar solvent" within the meaning of this patent application covers all chemical species, alone or in a mixture, comprising at least one carbon-hydrogen, carbon-halogen, carbon-chalcogen or carbon-nitrogen covalent bond and having a non-zero dipole moment. It is understood that the term "polar solvent" within the meaning of this definition specifically excludes water.

[0028] The term "solvent" includes the aforementioned "polar solvents" and non-polar solvents, which include, for example, any type of linear, branched, cyclic and / or aromatic saturated or unsaturated hydrocarbon such as pentane, cyclohexane, olefins, toluene or xylene or certain other solvents with zero or almost zero dipole moment such as tetrachloromethane or carbon disulfide.

[0029] The term "naphtha" refers to the general definition used in the oil and gas industry. Specifically, it is a hydrocarbon derived from the distillation of crude oil and has a boiling point between 15 and 250 °C, according to ASTM D2887. Naphtha contains virtually no olefins because the hydrocarbons are derived from crude oil. It is generally considered that a naphtha has a carbon number between C5 and C11, although the carbon number can reach C15 in some cases. It is also generally accepted that the density of naphtha is between 0.65 and 0.77 g / mL.

[0030] “Liquefaction oil” means an oil resulting from a pyrolysis process and / or a hydrothermal liquefaction process of a hydrocarbon feedstock. This hydrocarbon feedstock may include plastics, biomass and / or elastomers, alone or in a mixture, in particular in the form of waste. A liquefaction oil may be formed from a mixture of two or more liquefaction oils resulting from the liquefaction of different hydrocarbon feedstocks.

[0031] The pyrolysis process must be understood as a thermal cracking process, typically carried out at a temperature of 300 to 1000 °C or 400 to 700 °C, carried out in the presence or absence of a catalyst and / or a gas (fast pyrolysis, flash pyrolysis, catalytic pyrolysis, hydropyrolysis, steampyrolysis, etc.).

[0032] Hydrothermal liquefaction (HTL) is a thermochemical conversion process using water as a solvent, reactant, and catalyst for the degradation reactions of a hydrocarbon feedstock, the water typically being in a subcritical or supercritical state. The hydrothermal liquefaction process is typically carried out at a temperature of 250 to 500 °C and at pressures of 10 to 25-40 MPa in the presence of water.

[0033] The term "plastic liquefaction oil" or "oil resulting from the liquefaction of plastic" or "plastic waste liquefaction oil" or "liquefaction oil resulting from the liquefaction of waste containing plastics" or "plastic oil" refers to liquid hydrocarbon products obtained from pyrolysis or hydrothermal liquefaction of thermoplastic and / or thermosetting polymers, alone or in a mixture, and generally in the form of waste, optionally in a mixture with at least one other feedstock, in particular in the form of waste, such as biomass, for example, chosen from lignocellulosic biomass, herbaceous biomass (biomass of plants having a non-woody stem and which die at the end of the growing season) and / or aquifer biomass (plants growing in or under water such as algae), paper and cardboard, and / or an elastomer,for example possibly vulcanized latex or tires.,

[0034] Plastic can be of any type, including any type of new or used plastic, included in household (post-consumer) or industrial waste. Plastics are understood to mean materials consisting of polymers and optionally auxiliary components such as plasticizers, fillers, colorants, catalysts, flame retardants, stabilizers, etc. For example, these polymers can be polyethylene, halogenated polyethylene (Cl, F), polypropylene, polystyrene, polybutadiene, polyisoprene, poly(ethylene terephthalate) (PET), polylactic acid (PLA), acrylonitrile-butadiene-styrene (ABS), polybutylene, poly(butylene terephthalate) (PBT), polyvinyl chloride (PVC), polyvinylidene chloride, a polyester, a polyamide, a polycarbonate, a polyether, an epoxy polymer, a polyacetal, a polyimide, a polyesteramide, silicone, etc.Generally speaking, any polymer or mixture of polymers capable of producing hydrocarbons by liquefaction can be used.

[0035] Biomass can be defined as an organic plant or animal product, namely a product composed of agricultural or forestry plant matter or composed of animal matter, including vegetable or animal oils or fats. Biomass thus includes (i) biomass produced from surplus agricultural land, not used for human or animal food: dedicated crops, called energy crops; (ii) biomass produced by deforestation (forest maintenance) or the clearing of agricultural land; (iii) agricultural residues from cereal crops, vines, orchards, olive trees, fruits and vegetables, agri-food residues, etc.; (iv) forest residues from forestry and wood processing; (v) agricultural residues from livestock farming (manure, slurry, bedding, droppings, etc.); (vi) organic household waste (paper, cardboard, green waste, etc.)); (vii) ordinary industrial organic waste (paper, cardboard, wood, putrescible waste, etc.); (viii) algal biomass, namely biomass formed from algae, for example microalgae (the algal biomass may be an algae suspension obtained by harvesting algae from, for example, a bioreactor, or an algae residue obtained by dehydrating an algae suspension) or macroalgae; (ix) herbaceous biomass. The plastic liquefaction oil treated by the invention may originate from the liquefaction of waste containing at least 1% by weight, optionally from 1 to 50% by weight, from 2 to 30% by weight or in a range defined by any two of these limits, of one or more of the aforementioned biomasses, residues and organic waste, and the remainder consisting of plastic waste, optionally mixed with elastomers, in particular in the form of waste.

[0036] Elastomers are linear or branched polymers transformed by vulcanization into a weakly crosslinked, infusible and insoluble three-dimensional network. They include natural or synthetic rubbers. They can be part of tire-type waste or any other household or industrial waste containing elastomers, natural and / or synthetic rubber, mixed or not with other components, such as plastics, plasticizers, fillers, vulcanizing agents, vulcanization accelerators, additives, etc. Examples of elastomeric polymers include ethylene-propylene copolymers, ethylene-propylene-diene terpolymer (EPDM), polyisoprene (natural or synthetic), polybutadiene, styrene-butadiene copolymers, isobutene-based polymers, isobutylene-isoprene copolymers, chlorinated or brominated, butadiene-acrylonitrile copolymers (NBR), and polychloroprenes (CR), polyurethanes, silicone elastomers, etc.The plastic liquefaction oil treated by the invention may come from the liquefaction of waste containing at least 1% m / m, optionally from 1 to 50% m, from 2 to 30% m or in a range defined by any two of these limits, of one or more of the aforementioned elastomers, in particular in the form of waste, the remainder being made up of plastic waste, optionally mixed with biomass, residues and organic waste.

[0037] The term "MAV" (acronym for "Maleic Anhydric Value") refers to the UOP326-82 method which is expressed in mg of maleic anhydride which react with 1 g of sample to be measured.

[0038] The term "Bromine Number" is the amount of bromine in grams reacted in 100 g of sample and can be measured according to ASTM D1159-07.

[0039] The term "Bromine Index" is the number of milligrams of bromine that react with 100 g of sample and can be measured according to ASTM D2710 or ASTM D5776.

[0040] Boiling points as mentioned here are measured at atmospheric pressure, unless otherwise stated. An initial boiling point is defined as the temperature value from which a first vapor bubble is formed. A final boiling point is the highest temperature achievable during distillation. At this temperature, no more vapor can be transported to a condenser. The determination of the initial and final points uses techniques known in the art and several methods adapted according to the distillation temperature range are applicable, for example NF EN 15199-1 (2020 version) or ASTM D2887 for the measurement of boiling points of petroleum fractions by gas chromatography, ASTM D7169 for heavy hydrocarbons, ASTM D7500, D86 or D1160 for distillates.

[0041] Metal concentrations in hydrocarbon matrices can be determined by any known method. Acceptable methods include X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Analytical scientists can identify the most suitable method for measuring each metal and, in general, each heteroelement, depending on the hydrocarbon matrix under consideration. Oxygen content can be measured according to the standard: ASTM D5622-17 / D2504-88(2015). Nitrogen content can be measured according to the standard: ASTM D4629-17. Sulfur content can be measured according to ISO 20846:2011. Halogen content, including chlorine, bromine, and fluorine, can be measured according to the standard: ASTM D7359-18.

[0042] "Hydrotreatment" means any process in which hydrocarbons react with dihydrogen, typically under pressure, in the presence of a catalyst or not. Hydrotreatment may thus comprise one or more reactions chosen from hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrodemetalation (HCM), hydrocracking, hydroisomerization and hydrogenation (hydrogenation of unsaturated compounds into saturated compounds).

[0043] A "hydroprocessing catalyst" means a catalyst that promotes the incorporation of hydrogen into the products. This type of catalyst is typically a metal catalyst comprising one or more metals from groups 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 of the periodic table.

[0044] The particular features, structures, properties, embodiments of the invention may be freely combined into one or more embodiments not specifically described herein, as may be apparent to those skilled in the art in the processing of plastic liquefaction oils using their general knowledge.

[0045] Detailed description of the invention

[0046] In the following description, the different embodiments described, and in particular the preferred embodiments of each step, can be combined according to the desired objective.

[0047] Description of the composition comprising a plastic liquefaction oil

[0048] The composition provided in step a) comprises a plastic liquefaction oil. This plastic liquefaction oil may be a plastic pyrolysis oil, a plastic hydrothermal liquefaction oil or a mixture of both.

[0049] In a preferred embodiment, the composition may comprise only a plastic liquefaction oil.

[0050] Alternatively, the composition provided in step a) may comprise at least 1% by weight, or even at least 2% by weight of plastic liquefaction oil(s). The remainder may then be composed of at most 99% by weight, or at most 98% by weight, of a diluent or solvent such as a hydrocarbon and / or one or more components listed below.

[0051] In one embodiment, the composition may comprise at least 5% by weight, preferably 10% by weight, more preferably at least 25% by weight, even more preferably at least 50% by weight, more preferably 75% by weight, even more preferably at least 90% by weight of plastic liquefaction oil. The composition may comprise at most 80% by weight or 90% by weight or 95% by weight or 100% by weight of plastic liquefaction oil. The mass content of plastic liquefaction oil(s) in the composition may be within any range defined by two of the limits previously set.

[0052] The composition may further comprise one or more of the components derived from biomass, biomass waste or elastomeric waste, such as the following components: a tall oil, a used edible oil, an animal fat, a vegetable oil such as rapeseed, canola, castor, palm, soybean oil, an oil extracted from an algae, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, a biomass liquefaction oil, in particular a biomass liquefaction oil such as Panicum virgatum or a lignocellulosic or herbaceous or aquiferous biomass liquefaction oil, for example a wood, herbaceous, algae, paper and / or cardboard liquefaction oil, an oil obtained by liquefaction of crushed used furniture, an elastomer liquefaction oil for example optionally vulcanized latex or tires, as well as their mixtures.

[0053] The composition may further comprise a component which is a diluent miscible with the plastic liquefaction oil. This diluent preferably has a diene number of at most 0.5 g I2 / 100 g, measured according to UOP 326-17, a bromine number of at most 5 g Br2 / 100 g, measured according to ASTM D1159. The diluent is preferably selected from a naphtha and / or a paraffinic solvent and / or a straight run diesel or gas oil, containing at most 1% by weight of sulfur, preferably at most 0.1% by weight of sulfur, and / or a hydrocarbon stream having a boiling range between 50°C and 150°C or a boiling range between 150°C and 250°C or a boiling range between 200°C and 350°C, preferably having a bromine number of at most 5 g Br2 / 100 g, and / or a diene number of at most 0.5 g I2 / 100 g or any combination thereof.

[0054] The composition may have a bromine count of at most 150 g Br2 / 100 g, preferably at most 100 g Br2 / 100 g, even more preferably at most 80 g Br2 / 100 g, most preferably at most 50 g Br2 / 100 g, as measured according to ASTM D1159.

[0055] Step (a) of providing the composition may comprise:

[0056] (a1) a step of liquefying waste containing plastics and obtaining a hydrocarbon product comprising a gaseous phase, a liquid phase and a solid phase, (a2) a step of separating the liquid phase from said product, said liquid phase forming a plastic liquefaction oil,

[0057] (a3) an optional step of mixing the plastic liquefaction oil with a diluent or solvent.

[0058] The liquefaction step (a1) may comprise a pyrolysis step, typically carried out at a temperature of 300 to 1000°C or 400 to 700°C, this pyrolysis being, for example, a fast pyrolysis or a flash pyrolysis or a catalytic pyrolysis or a hydropyrolysis.

[0059] Alternatively or in combination, the liquefaction step (a1) may comprise a hydrothermal liquefaction step, typically carried out at a temperature of 250 to 500°C and at pressures of 10 to 25-40 MPa.

[0060] The waste treated in step (a1) may be plastic waste possibly mixed with biomass or other types of waste, as previously described. The separation step (a2) makes it possible to eliminate the gaseous phase, essentially C1-C4 hydrocarbons and the solid phase (typically char) to recover only the liquid organic phase forming a liquefaction oil.

[0061] Plastic liquefaction oils contain, among other things, paraffins, i-paraffins (isoparaffins), dienes, alkynes, olefins, naphthenes, and aromatics. Plastic liquefaction oils also contain impurities containing heteroatoms, such as chlorinated, oxygenated, sulfurous, nitrogenous, and / or silylated organic compounds, metals, salts, and phosphorus compounds.

[0062] The composition of plastic liquefaction oil depends on the nature of the liquefied plastic, and optionally on any other waste liquefied with the plastic, and is essentially (notably more than 80% m, most often more than 90% m) made up of hydrocarbons having 1 to 150 carbon atoms and impurities.

[0063] A plastic liquefaction oil typically comprises 5 to 80% by weight of paraffins (including cycloparaffins), 10 to 95% by weight of unsaturated compounds (including olefins, dienes and acetylenes), and 5 to 70% by weight of aromatics. These contents can be determined by gas chromatography.

[0064] In particular, a plastic liquefaction oil may comprise a Bromine number of 10 to 130 g Br2 / 100 g, as measured according to ASTM D1159, and / or a Maleic Anhydride Number (UOP326-82) of 1 to 55 mg Maleic Anhydride / 1 g.

[0065] In a preferred embodiment, said plastic liquefaction oil has an initial boiling point of at least 15°C, and a final boiling point of at most 800°C, preferably at most 600°C, even more preferably at most 560°C, more preferably at most 450°C, even more preferably at most 350°C, preferably 250°C (measured according to standard NF EN 15199-1 / 2).

[0066] A plastic liquefaction oil typically contains at least 20 ppm of heteroatoms, or even at least 30 ppm of heteroatoms. Its maximum heteroatom content can be 15% by mass.

[0067] A plastic liquefaction oil may include, but is not limited to, one or more of the following heteroatom contents: 0 to 8% wt. oxygen (measured according to ASTM D5622), 1 to 13,000 ppm nitrogen (measured according to ASTM D4629), 2 to 10,000 ppm sulfur (measured according to ISO 20846), 1 to 10,000 ppm metals (measured by ICP), 50 to 6,000 ppm chlorine (measured according to ASTM D7359-18), 0 to 200 ppm bromine (measured according to ASTM D7359-18), 1 to 40 ppm fluorine (measured according to ASTM D7359-18), 1 to 2,000 ppm silicon (measured by XRF). Between steps a) and b), the invention may also comprise an optional pretreatment step, in which said composition is subjected, in particular immediately before step b), to (i) filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). This additional step may make it possible to reduce some of the impurities contained in the composition such as oxygen, nitrogen, chlorine, sulfur or other heteroatoms. In particular, the reduction in the amount of oxygen may make it possible to avoid the formation of solids and / or gels during step (c1).

[0068] In the additional washing step (ii), the polar solvent or water / composition volume ratio may be from 1 / 99 to 90 / 10, from 10 / 90 to 90 / 10, from 20 / 80 to 80 / 20, from 30 / 70 to 70 / 30, from 35 / 65 to 65 / 35, from 35 / 65 to 60 / 40, or from 40 / 60 to 60 / 40.

[0069] When water is used for washing (ii), it may have an acidic, basic or neutral pH. An acidic pH may be obtained by the addition of one or more organic or inorganic acids. Examples of suitable organic acids include citric acid (CeHsO?), formic acid (CH2O2), acetic acid (CH3COOH). Examples of inorganic acids are sulfamic acid (H3NSO3), hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), phosphoric acid (H3PO4). A basic pH may be obtained by the addition of alkali and alkaline earth metal oxides, alkali and alkaline earth metal hydroxides (e.g., NaOH, KOH, Ca(OH)2), alkali and alkaline earth metal bicarbonates and amines (e.g., triethylamine, ethylenediamine, ammonia).

[0070] When water is used for washing, provision may be made to return all or part of the water recovered at the end of washing to step (c1). And optionally, when step (c1) is carried out with water, the water recovered at the end of washing in step (c1) may be returned in whole or in part to this washing step (ii).

[0071] The polar solvent may have a density greater or less than the density of the composition comprising a plastic liquefaction oil.

[0072] In particular, the density of the polar solvent may be 3 to 50% higher or lower than that of the composition.

[0073] The polar solvent is a solvent immiscible with the composition comprising a plastic liquefaction oil to be purified.

[0074] For example, the polar solvent (or a mixture of polar solvents where appropriate) may be considered immiscible when its recovery rate is greater than or equal to 0.95. This recovery rate is defined as the ratio of the volume of extract to the volume of initial solvent, this extract being a phase containing the solvent, immiscible with the composition containing a liquefaction oil, recovered after stirring and then decanting a mixture of one part by volume of solvent with twenty-five parts by volume of the composition containing a liquefaction oil to be purified, at atmospheric pressure and at a temperature of 20°C.

[0075] This recovery rate can be determined in particular by following the following procedure:

[0076] Introduction of 50 mL of composition containing a liquefaction oil into a flat-bottomed flask with a volume of 100 mL, using a precision pipette of + / -0.5 mL,

[0077] Introduce 2 mL of solvent into the flask, using a precision pipette + / -0.1 mL,

[0078] Insert a magnetic bar, close the balloon with a polypropylene stopper,

[0079] Stir the mixture on a mechanical stir plate at a speed of 500 rpm for 5 min,

[0080] At the end of the 5 minutes, stop stirring, remove the magnetic bar using a magnetic rod,

[0081] Transfer the contents of the flask into a graduated tube with an accuracy of + / -0.05 mL for a volume less than or equal to 2 mL and an accuracy of + / -0.1 mL for a volume greater than 2 mL. Wait for complete demixing by decantation and measure the volume of the 2 phases using the graduations. Complete demixing is considered to be achieved when the volumes of the two phases no longer vary.

[0082] Acceptable immiscible polar solvents include (i) sulfur compounds, for example dimethyl sulfoxide, (ii) nitrogen compounds, for example N,N-dimethylformamide, (iii) halogenated compounds, for example dichloromethane or chloroform, (iv) ethylene glycol, or: glycol ethers, including in particular polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH with a mass average molar mass of 90 to 800g / mol, for example diethylene glycol and tetraethylene glycol, polypropylene glycol of chemical formula H[OCH(CH3)CH2]nOH with a mass average molar mass of 130 to 800g / mol, for example dipropylene glycol and tetrapropylene glycol, dialkyl formamides, in which the alkyl group may comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethyl formamide (DMF), dialkyl sulfoxides, in which the alkyl group may comprise from 1 to 8 or from 1 to 3 carbon atoms,in particular dimethyl sulfoxide (DMSO) and sulfolane, compounds comprising a furan ring, cyclic carbonate esters, comprising in particular from 3 to 8 or from 3 to 4 carbon atoms, in particular propylene carbonate and ethylene carbonate. One or more of the above-mentioned solvents may be used. However, advantageously, only one of the above-mentioned solvents may be used provided that it is immiscible with the composition containing a liquefaction oil to be purified.,

[0083] Preferably, the polar solvent may be ethylene glycol or a glycol ether, in particular polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH with a mass average molar mass of 90 to 800g / mol or polypropylene glycol of chemical formula H[OCH(CH3)CH2]nOH with a mass average molar mass of 130 to 800g / mol, or a compound comprising a furan ring, or a cyclic carbonate ester, in particular propylene or ethylene carbonate, alone or as a mixture, preferably alone.

[0084] In a preferred embodiment, the polar solvent is chosen from propylene carbonate, ethylene carbonate, ethylene glycol and polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH with a mass average molar mass of 90 to 800g / mol, alone or as a mixture, preferably alone.

[0085] Detailed description of step b)

[0086] Step b) is a step of treating the composition provided in step a) in the presence of a basic compound at a temperature of at most 450°C to obtain an effluent comprising a treated composition.

[0087] This treatment makes it possible in particular to modify compounds containing heteroatoms and to promote their subsequent elimination.

[0088] Step b) is carried out in the presence of a basic compound, preferably a nucleophilic basic compound.

[0089] Advantageously, the amount of basic compound used is from 0.1 to 50% by weight, preferably at least 0.5% by weight, more preferably at least 1% by weight, preferably at least 3% by weight, even more preferably at least 5% by weight or even at least 10% by weight relative to the total mass of the composition treated (composition provided by step (a)).

[0090] Advantageously, the quantity of basic compound used may be from 0.1 to 15% by weight, more preferably from 0.5 to 15% by weight, even more preferably from 1 to 15% by weight, in particular from 3 to 15% by weight, or even from 5 to 15% by weight or from 10 to 15% by weight relative to the total mass of the composition treated (composition provided by step a)), or in any interval defined by two of the preceding limits.

[0091] The basic compound may be added to the composition provided by step a) either before step b) or during step b). This addition of the basic compound to the composition may optionally be followed by a mixing step before carrying out step b). The basic compound may be added to the composition in solid form or solubilized in an aqueous medium, preferably water, or in a solvent, miscible or immiscible with said composition, preferably immiscible.

[0092] When the basic compound is solubilized in a solvent or in water, the person skilled in the art will then choose a quantity of solvent or water sufficient to dissolve / solubilize it, preferably the smallest possible quantity of solvent or water, or just sufficient to saturate the solvent or water with the basic compound.

[0093] The volume ratio of solvent / water containing the basic compound / organic phase, i.e. the volume ratio of the mixture (basic compound + solvent or water) / organic phase, may be from 0.1 / 99.9 to 80 / 20, from 1 / 99 to 80 / 20, from 1 / 99 to 70 / 30, from 1 / 99 to 65 / 35, from 1 / 99 to 60 / 40, from 1 / 99 to 50 / 50, or in any interval defined by any two of the above limits.

[0094] Advantageously, the basic compound added in step b) is in solution in water or in a solvent, and the content of basic compound in the water or solvent is from 0.1 to 50% m, preferably from 15 to 50% m, more preferably from 25% to 50% m, more preferably from 40 to 50% m, even more preferably the water or the solvent is saturated with basic compound, in particular the water or the solvent contains just enough basic compound to obtain a saturated solution.

[0095] Advantageously, the basic compound added in step b) is in solution in water. Thus, during step b), the organic phase may be brought into contact with an aqueous solution of a basic compound, preferably a basic compound comprising an alkali or alkaline-earth metal cation. A solution, in particular an aqueous solution, saturated with basic compound may advantageously be used. In particular, step b) may be carried out without adding any solvent other than water or a solvent possibly already present in the composition.

[0096] A miscible solvent that can be used may be a polar solvent comprising an alcohol function and / or an ether function, ideally chosen from C1 to C4 alcohols, preferably from methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, propylene glycol.

[0097] A usable immiscible solvent may be an immiscible polar solvent, for example those cited for the optional pre-treatment step.

[0098] In one embodiment, the basic compound may comprise an oxide, hydroxide, bicarbonate, or alkoxide of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or bicarbonate of a quaternary ammonium cation, for example, a tetramethylammonium (TMA+), tetraethylammonium (TEA+), tetrapropylammonium (TPA+), or tetrabutylammonium (TBA+) cation. Preferably, the basic compound may comprise an oxide, hydroxide, or bicarbonate of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or bicarbonate of a quaternary ammonium cation. More preferably, the basic compound may comprise one of the above-mentioned oxide or hydroxide, alone or in a mixture.

[0099] In a preferred embodiment, the basic compound may be selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, EtONa, MeONa, NH4OH, TEAOH, TBuOH, TMAOH, and mixtures thereof or from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, TEAOH, TBuOH, TMAOH, and mixtures thereof. A preferred basic compound may be selected from NaOH, KOH and mixtures thereof, preferably in solution in water or in a solvent, in particular a solvent immiscible with the composition.

[0100] The solvent used to solubilize the basic compound may be water, an alcohol, for example methanol or ethanol, or any other organic solvent capable of solubilizing the chosen basic compound, preferably water or a solvent immiscible with the composition.

[0101] In a preferred embodiment, prior to step b) or during step b), it is possible to add to the composition of step a) (i) a solid basic compound, (ii) a basic compound previously solubilized in an aqueous medium, preferably water, or (iii) a basic compound previously solubilized in a solvent, preferably a polar solvent immiscible with said composition, the content of basic compound in the water or solvent being from 15 to 50% by mass, preferably from 25% to 50% by mass, more preferably from 40 to 50% by mass. This embodiment can in particular be combined with the temperature conditions and other operating conditions described below. This embodiment can also be combined with the particularly preferred embodiment described below.

[0102] Step b) may be carried out at a temperature of at most 450°C. In one embodiment, step b) may be carried out at a temperature of 50 to 450°C, preferably 50 to 350°C, more preferably 50 to 250°C, more preferably still 50 to 225°C, 50 to 200°C, 70 to 190°C or 80 to 185°C, or in any range defined by any two of these limits.

[0103] Treatment step b) can be carried out at an absolute pressure of 0.1 to 100 bars, preferably 1 to 50 bars.

[0104] In a particularly preferred embodiment, step b) is carried out for a period of 1 minute to 3 hours, preferably 1 minute to 1 or 2 hours, more preferably 1 minute to 20 minutes, preferably 1 minute to 16 minutes, at a temperature of at most 250°C, more preferably at most 225°C, even more preferably at most 200°C, 190°C or 185°C. In this particularly preferred embodiment, step b) can be carried out at a temperature of at least 50°C, preferably at least 90°C, more preferably at least 150°C. In this particularly preferred embodiment, step b) can be carried out at an absolute pressure of 0.1 to 100 bar, preferably 1 to 50 bar.

[0105] In this particularly preferred embodiment, the composition provided by step a) can advantageously be brought into contact with:

[0106] - 0.1 to 15% by weight of a basic compound, advantageously comprising an alkali or alkaline-earth metal cation, and preferably in the presence of water, preferably with 0.5 to 15% by weight of a basic compound, more preferably with 1 to 10% by weight of a basic compound (mass percentages of basic compound relative to the composition), and / or

[0107] - with water containing from 15 to 50% by weight of basic compound, preferably from 25% to 50% by weight, more preferably from 40 to 50% by weight (mass percentages of basic compound relative to water), even more preferably with water saturated with basic compound.

[0108] A preferred strong base may be selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, TMAOH, TEAOH, TBuOH, EtONa, MeONa and mixtures thereof. A more preferred strong base may be selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, TMAOH, TEAOH, TBuOH, and mixtures thereof, and in particular from NaOH, KOH and mixtures thereof, in particular for the implementation of the particularly preferred embodiment.

[0109] At the outlet of step b), a first effluent containing a modified composition is obtained because the impurities (the compounds containing heteroatoms) have been modified by the treatment of step b). The first effluent containing the modified composition obtained at the outlet of step b) makes it possible to subsequently obtain a purified composition comprising a reduced heteroatom content, as explained below.

[0110] Detailed description of the optional additional solids separation step

[0111] Step c), and in particular one or more of steps (c1) and (c2), may be preceded or followed by a step of separating the solids by (i) filtration, (ii) centrifugation, (iii) hydrocyclone or (iv) a combination of two or three of these steps. This step of separating the solids is particularly advantageous before step (c2) because it can facilitate the separation of the phases by eliminating all or part of the solids present in the first effluent from step b).

[0112] In step c), the effluent from step b) may be subjected to (c1) washing with water or a solvent immiscible with the modified composition, (c2) separation, or to the succession of steps (c2) and (c1). This step c) makes it possible to recover a purified composition having a reduced heteroatom content and a phase (solid or liquid) containing the basic compound and heteroatoms initially contained in the modified composition. This step thus makes it possible to separate the impurities from the composition.

[0113] The choice of steps (c1), (c2) or (c2) + (c1) depends in particular on the nature of the basic compound and the desired purification objective. For example, we can distinguish cases (A), (B) and (C) below:

[0114] (A) the basic compound is added to the composition of step a) in the form of a solid basic compound, step c) may then comprise:

[0115] (A1) the washing step (c1) which makes it possible to recover a phase containing the purified composition and a phase containing the basic compound, the impurities, and the water or the solvent used for washing, or

[0116] (A2) the separation step (c2), typically a solid-liquid extraction, which makes it possible to separate a solid phase comprising the basic compound and the impurities having precipitated and a liquid phase containing the purified composition, or

[0117] (A3) the separation step (c2) described above followed by a washing step (c1) of the liquid phase containing the purified composition recovered at the outlet of step (c2),

[0118] (B) the basic compound is added to the composition of step a) solubilized in a solvent miscible with the composition, step c) can then comprise the washing step (c1) which makes it possible to recover a phase containing the purified composition and a phase containing the miscible solvent, the solubilized basic compound, the impurities, and the water or the immiscible solvent used for washing;

[0119] (C) the basic compound is added to the composition of step a) solubilized in an aqueous medium or in a solvent immiscible with the composition, step c) can then comprise:

[0120] (C1) the washing step (c1) which makes it possible to recover a phase containing the purified composition and a phase containing the basic compound, the impurities, the water or the solvent used for washing and the aqueous medium or the immiscible solvent used to add the basic compound, or

[0121] (C2) the separation step (c2), typically a liquid-liquid separation, which makes it possible to separate the phase containing the purified composition and a phase containing the water or the immiscible solvent, the basic compound and the impurities, or

[0122] (C3) the separation step (c2) described above followed by a washing step (c1) of the phase containing the purified composition recovered at the outlet of step (c2).

[0123] When step c) implements separation (c2), namely in cases (A2), (A3), (C2) and (C3), it will be advantageous to recover the phase containing the basic compound recovered at the outlet of the separation step (c2) and return it in whole or in part to the treatment step b). This makes it possible to reduce the quantities of basic compound to be used and thus reduce the associated costs.

[0124] The washing step (c1) is carried out with water at neutral, basic or acidic pH or with a solvent immiscible with the purified composition, preferably with water. The washing step (c1) makes it possible to recover a phase containing the purified composition and a phase containing the water or the immiscible solvent used for washing, the basic compound and the impurities. In other words, at the outlet of the washing step, these phases are recovered separately, for example following a liquid / liquid separation (centrifugation and / or decantation and / or other) carried out at the end of the washing step.

[0125] This step (c1) makes it possible to eliminate the impurities containing heteroatoms present in the first effluent containing the modified composition leaving step b) by solubilizing them in a solvent (water or an organic solvent).

[0126] This washing step (c1) can also make it possible to separate the basic compound from the purified composition. The washing step (c1) is thus particularly advantageous when the basic compound used during step b) is added to the composition in solid form or dissolved in a solvent miscible with the composition to be treated, but can also be carried out when the basic compound is in solution in a solvent (water or organic solvent) immiscible with the composition to be treated.

[0127] When the basic compound used in step b) is solid or solubilized in water or a solvent immiscible with the composition, this washing step (c1) can be omitted or carried out after the separation step (c2), as explained below.

[0128] The water used in step (c1) can have an acidic pH (pH<7), basic (pH >7) or neutral (PH=7).

[0129] In one embodiment, the water used has an acidic or neutral pH. In particular, the water used does not contain a basic compound and in particular does not contain a basic compound comprising an alkali or alkaline earth metal cation.

[0130] An acidic pH may be obtained by the addition of one or more organic or inorganic acids. Examples are given with reference to washing (ii) of the optional pre-treatment step. Preferably, the water may have a pH of 0.1 to 6.9.

[0131] A basic pH may be obtained by adding a basic compound, for example those mentioned above with reference to wash (ii) of the optional pre-treatment step or those used in step b). Preferably, the water may have a pH of 7.1 to 14.

[0132] The immiscible solvent may be any organic solvent immiscible with the composition, in particular in which the impurities containing heteroatoms are soluble. A usable immiscible solvent is, for example, a polar solvent, in particular those described in the optional pre-treatment step.

[0133] Step (c1) may be carried out at a temperature of 10°C to 120°C, preferably 15°C to 95°C, more preferably 15°C to 80°C, or in any range defined by any two of these limits, advantageously without external heating. Step (c1) is typically carried out at atmospheric pressure or at a pressure close to the pressure at which step b) is carried out.

[0134] Step (c1) can be carried out on the first effluent directly from step b), without an intermediate step, or on the effluent containing the purified composition leaving step (c2). When it follows step (c2), the washing step (c1) then makes it possible to eliminate any residue of the basic compound and / or impurities containing heteroatoms, still present in the purified composition leaving step (c2), which can make it possible to obtain a purified composition having in particular a chlorine content of less than or equal to 30 ppm (by mass) and a sodium content of less than or equal to 2 ppm (by mass).

[0135] During step (c1), the volume ratio of solvent or water / effluent containing the purified composition may be from 1 / 99 to 90 / 10, from 20 / 80 to 80 / 20, from 30 / 70 to 70 / 30, from 35 / 65 to 65 / 35, from 35 / 65 to 60 / 40, from 40 / 60 to 60 / 40, or in any interval defined by any two of the aforementioned limits.

[0136] Step (c1) may comprise, or consist of, bringing the effluent from step b) or (c2) into contact with water or an immiscible solvent by any means known in the prior art.

[0137] For example, the effluent from step b) or (c2) and the solvent or water may be introduced into tanks, reactors or mixers commonly used in the profession and the two components may be mixed. The contacting may comprise vigorous stirring of the two components by a mixing device. For example, the two components may be mixed together by stirring or shaking. Alternatively, the contacting may be carried out in an enclosure in which the two components circulate in countercurrent, for example in contact columns with adequate packing in order to increase the contact between the phase of the composition being treated and the water or an immiscible solvent. Alternatively, the contacting may be carried out in another static mixer in co-current mode or in a cavitation enclosure. This contacting may occur more than once, in particular under the conditions presented above.

[0138] The washing step (c1) can be carried out continuously or in batch.

[0139] Detailed description of separation step (c2)

[0140] The separation step (c2) also makes it possible to separate the purified composition to obtain a phase containing the purified composition having a reduced heteroatom content, and a phase containing the basic compound and the impurities. This may be a liquid / liquid separation or a solid / liquid separation. It may advantageously be carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps.

[0141] Step (c2) can be carried out directly on the effluent containing the modified composition of step b). In this case, it makes it possible to separate the purified composition from the basic compound, in particular when the latter has been added in solid form or in a solvent immiscible with the composition (water or immiscible organic solvent). This step (c2) then separates a phase containing the purified composition and a phase containing the basic compound and the impurities, and, where appropriate, the water or the solvent immiscible with the composition. This phase containing the basic compound can then be returned to step b) to reuse the basic compound. This makes it possible to reduce the total quantity of basic compound consumed in step b).

[0142] Prior to step (c2), the effluent containing the modified composition leaving step b) may be treated in at least one mechanical or electrostatic coalescer in order to break any emulsion and concentrate the basic compound in the solvent or water.

[0143] Step (c2) may be carried out at a temperature of 10°C to 120°C, preferably 15°C to 95°C, more preferably 15°C to 80°C, or in any range defined by any two of these limits, advantageously without external heating. Step (c2) is typically carried out at atmospheric pressure or at a pressure close to the pressure at which step b) is carried out.

[0144] Detailed description of the optional catalytic hydrotreatment step

[0145] Upstream of gasification step e), advantageously upstream of optional distillation step d), preferably downstream of the optional solids separation step when present, the effluent containing the purified composition may be subjected to hydrotreatment in a single step or in two steps.

[0146] When this hydrotreatment is carried out in a single stage, the effluent is hydrotreated at a temperature of 200 to 450°C, preferably 200 to 380°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence of a hydrotreatment catalyst, for example a catalyst of the NiMo (0.1-60% by mass) and / or CoMo (0.1-60% by mass) type generally on a support.

[0147] Alternatively, the hydrotreatment can be carried out in a first step (1) in which the effluent is hydrotreated, preferably selectively hydrogenated, at a temperature of 80 to 250°C, preferably 130 to 250°C in the presence of hydrogen at an absolute pressure of 5 to 150 bars, preferably 20 to 100 bars, and in the presence of a first hydrotreatment catalyst, preferably a hydrogenation catalyst, for example a hydrogenation catalyst comprising Pd (0.1-10% by weight) and / or Ni (0.1-60% by weight) and / or NiMo (0.1-60% by weight), and in a second step (d-2) in which the effluent from step (d-1) is hydrotreated at a temperature of 200 to 450°C, preferably 250 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 150 bars, preferably 30 to 100 bars and in the presence of a second hydrotreatment catalyst, for example a catalyst of the NiMo (0.1-60% by weight) and / or CoMo (0.1-60% by weight) type.The first step can then allow the hydrogenation of dienes initially present in the composition.

[0148] This hydrotreatment step can be carried out in a single reactor with several catalytic beds placed in series with possible hydrogen additions between the beds or in several reactors in series depending on the desired objective.

[0149] This hydrotreatment step can also have a demetallation, cracking, dearomatization function depending on the characteristics of the catalyst and the hydrotreatment conditions.

[0150] Preferably, the feedstock for the hydrotreatment, containing at least a portion of the purified composition, may be diluted with a portion of the hydrotreatment effluent, still having a higher temperature than the desired temperature at the inlet to the hydrotreatment. This at least partial recycling of the hydrotreatment effluent makes it possible to dilute the unsaturates present in the purified composition and to preheat the feedstock.

[0151] Preferably, the part of the effluent from the hydrotreatment which is not recycled but still at a high temperature, can exchange its sensible heat with the composition comprising a plastic liquefaction oil and thus ensure the preheating of this composition entering step b).

[0152] The effluent leaving the hydrotreatment step, namely the purified and hydrotreated composition, optionally purified by passage over a solid adsorbent, can be washed with water to remove inorganic compounds such as hydrosulfide, hydrogen chloride and ammonia before being subjected to further treatments.

[0153] The second effluent from step c) or the effluent from the hydrotreatment step can be purified by passing it over a solid adsorbent in order to reduce the content of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and / or the water content.

[0154] The adsorbent may be operated in regenerative or non-regenerative mode, at a temperature below 400°C, preferably below 100°C, more preferably below 60°C, chosen from: (i) a silica gel, (ii) a clay, (iii) a crushed clay, (iv) apatite, (v) hydroxyapatite and combinations thereof, (vi) an alumina, for example an alumina obtained by boehmite precipitation, a calcined alumina such as Ceralox ® from Sasol, (vii) boehmite, (viii) bayerite, (ix) hydrotalcite, (x) a spinel such as Pural ® or Puralox from Sasol, (xi) a promoted alumina, for example Selexsorb ® from BASF, an acid promoted alumina, an alumina promoted by a zeolite and / or by a metal such as Ni, Co, Mo or a combination of at least two of them, (xii) an acid-treated clay such as Tonsil ® from Clariant, (xiii) a molecular sieve in the form of an aluminosilicate containing an alkali or alkaline earth cation for example sieves 3A, 4A,5A, 13X, for example marketed under the brand Siliporite ® from Ceca, (xiv) a zeolite, (xv) an activated carbon, or the combination of at least two adsorbents, the adsorbent or the at least two adsorbents retaining at least 20% by weight, preferably at least 50% by weight of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and / or water.,

[0155] According to a preferred embodiment, the adsorbent is regenerable, has a specific surface area of ​​at least 200 m 2 / g and is operated in a fixed bed reactor at less than 100 °C with a WH of 0.1 at 10 h' 1 .

[0156] Detailed description of the optional distillation separation step

[0157] The second effluent produced during step c), optionally hydrotreated, purified on an adsorbent and / or washed with water, can be separated d) by distillation into at least two distinct fractions, typically a heavy fraction and a light fraction.

[0158] It is then possible to send one of these fractions to gasification step e), advantageously, a heavy fraction or the heaviest fraction is sent to gasification step e).

[0159] This separation can be carried out in particular by distillation, in particular by atmospheric distillation or by distillation under reduced pressure.

[0160] This can make it possible to separate the second effluent into two or more fractions, the lighter fraction(s) being able, for example, to be sent to refining units of the steam cracking or other type, and the heavy fraction(s) being sent to step e).

[0161] The second effluent produced during step c), optionally hydrotreated, purified on an adsorbent and / or washed with water, can in particular be fractionated into usable streams whose cut points are typically chosen according to the subsequent treatment. This fractionation can be carried out according to distillation temperature ranges, for example to separate streams of the LPG, gasoline, diesel, heavy fuel oil, kerosene type, which can then be treated in a gasifier and / or a steam cracker and / or in a catalytic cracker and / or in a hydrocracker (then possibly in a steam cracker) and / or in a hydrotreatment reactor and / or used as such for the preparation of fuels, combustibles, lubricants or base oils. A person skilled in the art knows how to select the most suitable cuts for the subsequent treatment units according to the desired objective.

[0162] In particular, fractions 350 + °C or 375+ °C will be advantageously sent to step e) of gasification. The fractions 350 + °C, respectively 375+ °C correspond to fractions whose initial boiling point is greater than or equal to 350 °C, respectively 375 °C.

[0163] The second effluent from step c), optionally after solid / liquid separation and / or hydrotreatment, or one of the fractions from step d), may be subjected, alone or in a mixture with another hydrocarbon feedstock, to a gasification process to produce synthesis gas comprising at least dihydrogen, carbon monoxide and carbon dioxide.

[0164] The other hydrocarbon feedstock comes from the processing of crude oil. This hydrocarbon feedstock generally corresponds to a 350 cut + °C or 375 +°C. This is typically a visbroken residue, a VGO (vacuum gas oil), a residue from atmospheric distillation, a residue from vacuum distillation, a residue from visbroken vacuum distillation, alone or in a mixture.

[0165] Depending on the initial heteroatom contents of the plastic liquefaction oil, the second effluent from step c), optionally after solid / liquid separation and / or hydrotreatment, or one of the fractions from step d), may be subjected to the gasification step in a mixture with other conventional feedstocks of petroleum origin, in particular depending on the volumes available and / or so that the heteroatom content of the feedstock entering the gasification step has a heteroatom content that complies with the required requirements.The feedstock of the gasification step may in particular contain up to 100% by mass, 90% by mass, 80% by mass, 70% by mass, 60% by mass, 50% by mass, 40% by mass, 30% by mass, 20% by mass, 15% by mass, 10% by mass or 5% by mass of the second effluent of step c), optionally after solids / liquid separation and / or hydrotreatment, or of one of the fractions of step d), or in any interval defined by two of these limits.

[0166] This gasification step may be a partial oxidation gasification step carried out in a partial oxidation gasification unit to produce a synthesis gas comprising at least dihydrogen, carbon monoxide and carbon dioxide.

[0167] The second effluent from step c) or one of the fractions from step d) may, before step e), be mixed with another hydrocarbon feedstock such as naphtha, gas oil or any crude oil refining product to have a purified composition concentration ranging from 0.01% m to at most 90% m, preferably from 0.1% m to 75% m, even more preferably from 1% m to 50% m or within any of these limits.

[0168] As used in this document, the term "partial oxidation gasification (PCX) unit or facility" or "PCX gasification facility" means a facility that includes all equipment, lines, and controls necessary to perform PCX gasification of liquefied plastic waste. For example, the gasification facility may include a gasifier, a feed injector, a gasifier ball mill, a feed spray unit, and / or a solidification tank.

[0169] As used herein, the term "partial oxidation" refers to the high-temperature conversion of a carbon-containing feedstock to synthesis gas (carbon monoxide, hydrogen, and carbon dioxide), where the conversion is carried out with an amount of oxygen that is less than the stoichiometric amount of oxygen required for the complete oxidation of carbon to CO2. Reactions that occur in a partial oxidation (POX) gasifier include the conversion of a carbon-containing feedstock to synthesis gas, and specific examples of reactions include, but are not limited to, partial oxidation, water gas shift - primary reactions, the Boudouard oxidation reaction, methanation, hydrogen reforming, steam reforming, and carbon dioxide reforming.

[0170] The present technology is generally directed to a process for producing synthesis gas (syngas) from a plastic liquefaction oil composition. The process generally comprises introducing into a POX gasifier the plastic liquefaction oil composition and an oxidizing agent comprising molecular oxygen (O2) and carrying out a partial oxidation reaction in the gasifier by reacting at least a portion of the plastic liquefaction oil and at least a portion of the molecular oxygen. The plastic liquefaction oil composition may be in a solid or liquid form before being introduced into the POX gasifier.

[0171] The POX gasification plant comprises at least one POX gasification reactor or gasifier. In one embodiment or in combination with any of the embodiments mentioned, the POX gasification unit may comprise a liquid-fed gasifier or a solid-fed gasifier. More particularly, in various embodiments, the POX gasification unit may perform liquid-fed POX gasification. As used herein, the term "liquid-fed POX gasification" refers to a POX gasification process in which the process feed comprises primarily liquid components at 25°C and 1 atm. Additionally, or alternatively, in various embodiments, the POX gasification unit may perform solid-state POX gasification.The term "solid-state POX gasification" refers to a POX gasification process in which the process feed primarily comprises components that are solid at 25°C and 1 atm. Liquid- and solid-fed POX gasification processes may be co-fed with lesser amounts of other components having a different phase at 25°C and 1 atm. Thus, solid-fed POX gasifiers may be co-fed with liquids, but only in amounts (by mass) less than the amount of solids fed to the solid-fed POX gasifier.In one embodiment or in combination with any of the embodiments mentioned, the total feed to a liquid-fed POX gasifier may comprise at least 60, or at least 70, or at least 80, or at least 90, or at least 95% by mass of components that are liquid at 25°C and 1 atm; and the total feed to a solid-fed POX gasifier may comprise at least 60, or at least 70, or at least 80, or at least 90, or at least 95% by mass of components that are solid at 25°C and 1 atm.

[0172] In one embodiment or in combination with any embodiment mentioned herein, the oxidizing agent comprises an oxidizing gas which may include air, oxygen-enriched air, or molecular oxygen (O2), or steam.

[0173] Partial oxidation gasification can be carried out in the presence or absence of a catalyst. Suitable catalysts include one or more metal components from groups 8 to 10 of the periodic table, such as platinum, palladium, rhodium, iridium, osmium, ruthenium, and optionally, one or more elements from groups 5 to 7, 11, such as iron, cobalt, nickel, copper, vanadium and chromium, these elements typically being supported on a support such as zirconia, alumina, CeC>2, Y2O3 or TiG>2-

[0174] In one embodiment or in combination with any embodiment mentioned herein, the gasification zone, and optionally all reaction zones in the gasifier / gasification reactor, may operate at a temperature of at least 1000°C, at least 1100°C, at least 1200°C, at least 1250°C, or at least 1300°C and / or not more than 2500°C, not more than 2000°C, not more than 1800°C, or not more than 1600°C. The reaction temperature may be autogenous. Advantageously, the gasifier operating in steady state may be at an autogenous temperature and does not require the application of external energy sources to heat the gasification zone.

[0175] In one embodiment or in combination with any embodiment mentioned herein, the gasifier may operate at a pressure within the gasification zone (or combustion chamber) of at least 1.3 MPa to 9 MPa, examples of suitable pressure ranges include 2 to 7 MPa, 2 to 6 MPa, 2.5 to 7 MPa, 2 to 5.5 MPa, 3 to 5 MPa or any range defined by any of the limits of these ranges.

[0176] In general, the average residence time of the gases in the gasification reactor may be very short to increase the throughput. Since the gasifier may operate at a high temperature and pressure, substantially complete conversion of the feedstock to gas may occur in a very short time. In one embodiment or in combination with any embodiment mentioned herein, the average residence time of the gases in the gasifier may be no more than 30, no more than 25, no more than 20, no more than 15, no more than 10, or no more than 7 seconds.

[0177] In general, the raw syngas stream discharged from the gasification reactor includes gases such as hydrogen, carbon monoxide, and carbon dioxide and may include other gases such as methane, hydrogen sulfide, and nitrogen depending on the fuel source and gasification conditions. Description of Figures

[0178] Figure 1 depicts a possible embodiment of the invention. In this possible embodiment, the composition comprising a plastic liquefaction oil (1) is first optionally pretreated in the pretreatment section (A) to be subjected therein to a pretreatment (PTT) by (i) filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). The composition (1) or the pretreated composition

[0179] (2) is then sent to a treatment section (B) in the presence of a basic compound

[0180] (3) implementing step b) of the invention. The first effluent (4) leaving step b) and containing the modified composition can then be sent to an optional solids separation section (S1). The effluent (5) leaving section (S1) or the first effluent (4) leaving section (B) is then sent to a separation section (C) implementing step c) of the present invention, consisting of washing step (c1), separation step (c2) or the succession of steps (c2) and (c1). When this section (C) implements step (c2), the separated phase (7) containing the basic compound can be returned to the treatment section (B). The second effluent (6) leaving section (C) and containing the purified composition having a reduced heteroatom content, can then be sent to an optional solids separation section (S2) or to an optional hydrotreatment section (HDT) or to an optional distillation section (D).Thus, the effluent (7) from the optional solids separation section (S2) or the effluent (8) from the optional hydrotreatment section (HDT) can be sent to the optional distillation section (D) to carry out step d) and be separated there into at least two fractions (9a) and (9b). One of the two fractions, preferably the heavier fraction (9b), is then sent to the gasification unit (E) to carry out step e) and obtain a synthesis gas (10). Alternatively or in combination, the effluent (6) from section (C), the effluent (7) from the optional solids separation section (S2) or the effluent (8) from section (HDT) can be sent directly to the gasification section (E).

[0181] In a particularly advantageous embodiment, the installation comprises sections (B), (S1), (C), (D) and (E).

[0182] Examples

[0183] Embodiments of the present invention are illustrated by the following non-limiting examples.

[0184] Example 1: Purification of plastic pyrolysis oil in the presence of a strong base and water followed by washing with water

[0185] The physicochemical characteristics of the plastic pyrolysis oil used are described in Table 1, below. This product is a good representation of the general quality of plastic pyrolysis oils, even though the chlorine content is not very high. Table 1

[0186] Test protocol:

[0187] A 1.5 L AISI-316L grade stainless steel autoclave equipped with mechanical stirring is charged with HPP4 pyrolysis oil, a strong base in the form of NaOH and water, the strong base being solubilized in water before its introduction into the autoclave (Table 2). The sum of the volume of pyrolysis oil and the volume of water introduced is approximately 600 mL at room temperature, without taking into account the possible effects of volume variation during their mixing. The autoclave is closed and the gaseous headspace in the autoclave is flushed with nitrogen for 30 minutes. The autoclave is then heated under autogenous pressure with stirring at a speed of 400 to 1500 rpm to a temperature of 225 °C for a period of 30 minutes, once the target temperature has been reached. The heating rate is set at 30 °C / 10 minutes.

[0188] Table 2 After the reaction, the autoclave was cooled to room temperature and then the mixture was discharged and washed three times with water, each time using a water / feed volume ratio of 40 / 60, to remove strong base residues and water-soluble impurities. The resulting purified and washed pyrolysis oil was analyzed for residual impurity content (Table 3).

[0189] Table 3

[0190] The data in Table 3 show that the use of sodium hydroxide in the presence of water followed by washing significantly reduces the impurities initially contained in the pyrolysis oil as well as the sodium introduced by the sodium hydroxide treatment. The pyrolysis oil can then either be used as is or optionally be dried on an adsorbent such as a molecular sieve or an anhydrous salt, for example Na2SO4, and is then distilled under reduced pressure in order to remove any possible traces of solids, for example strong base, adsorbent residue, anhydrous / hydrated salt or gums.

[0191] Example 2: Mixture of the product of example 1 with a petroleum product We consider a petroleum product of type WR (Visbroken Vacuum Residue) having the following characteristics (table 4):

[0192] Table 4

[0193] The mixtures below of said WR are considered with the product of example 1 (treated HPP4) or with the initial untreated HPP4 (HPP4), according to their silicon and chlorine levels (table 5). The mixtures are expressed as a mass percentage of HPP4, treated or not. The column "Gasifier Specification and downstream units" corresponds to the maximum admissible values ​​of silicon and chlorine levels in a product, before injection into a gasifier.

[0194] Table 5

[0195] In this example, the treatment process according to the invention for HPP4 oil thus makes it possible to introduce it at a rate of 10% by mass into a mixture with the WR, while satisfying the requirements for the gasification stage and its downstream units. Depending on the heteroatom contents of the treated plastic liquefaction oil or depending on the volumes obtained, it may be possible to consider treating it in a gasification stage alone or in a mixture with other conventional feedstocks of petroleum origin.

Claims

Claims 1. A process for the gasification treatment of a composition comprising a plastic liquefaction oil, comprising the following steps: a) providing a composition comprising a plastic liquefaction oil containing at least 20 ppm by mass of heteroatoms, b) contacting the composition provided in step a) with a basic compound at a temperature of at most 450°C to obtain a first effluent containing a modified composition, c) subjecting the first effluent from step b) to (c1) washing with water or a solvent immiscible with the modified composition, (c2) separation, or to the succession of steps (c2) and (c1), and obtaining a second effluent containing a purified composition having a reduced heteroatom content, and a phase containing the basic compound and heteroatoms initially contained in the modified composition, d) optionally,the second effluent from step c) is separated by distillation into at least two separate fractions, e) subjecting the second effluent from step c) or one of the fractions from step d), alone or in a mixture with another hydrocarbon feedstock, to a gasification process to produce synthesis gas comprising at least dihydrogen, carbon monoxide and carbon dioxide, and in which, - prior to step b) or during step b), the following are added to the composition of step a): (i) a solid basic compound, (ii) a basic compound previously solubilized in an aqueous medium, preferably water, or (iii) a basic compound previously solubilized in a polar solvent immiscible with said composition, the content of basic compound in the water or solvent being 15 to 50% by mass.

2. Method according to claim 1, in which step b) is carried out in the presence of 0.1 to 50% by weight of basic compound relative to the total mass of the composition treated.

3. A method according to any one of claims 1 or 2, wherein step b) is characterized in that the basic compound comprises an oxide, a hydroxide, a bicarbonate or an alcoholate of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or as a mixture.

4. Method according to any one of claims 1 to 3, in which step b) is characterized in that the basic compound is chosen from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, TMAOH, TEAOH, TBuOH, MeONA, EtONa and mixtures thereof.

5. Method according to any one of claims 1 to 4, characterized in that step b) comprises one or more of the following characteristics: - step b) is carried out at a temperature of 50 to 450°C, preferably 50 to 350°C, more preferably 50 to 250°C, more preferably 50 to 225°C, 50 to 200°C, 70 to 190°C or 80 to 185°C, - step b) is carried out for a period of 0.1 seconds to 3 hours, preferably 0.1 seconds to 2 hours, more preferably 1 minute to 1 hour, 1 minute to 20 minutes or 1 minute to 16 minutes.

6. Process according to any one of claims 1 to 5, wherein, prior to the treatment of step b), said composition provided by step a) is subjected to (i) filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv).

7. Method according to any one of claims 1 to 6, characterized in that step c) is preceded or followed by a step of separation of the solids by (i) filtration, (ii) centrifugation, (iii) hydrocyclone or (iv) a combination of two or three of these steps.

8. Process according to any one of claims 1 to 7, characterized in that step c) is followed, optionally before the optional separation step d), by one or more of the following treatments (i) a purification treatment by passage over a solid adsorbent in order to reduce the content of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and / or the water content, (ii) a catalytic hydrotreatment in one or two stages to provide a purified hydrotreated composition.

9. Method according to any one of claims 1 to 8, characterized in that step c) comprises at least the separation step (c2) for separating the phase containing the basic compound and heteroatoms, and the purified composition, and in that the phase containing the basic compound and heteroatoms is returned in whole or in part to step b).

10. Method according to any one of claims 1 to 9, characterized in that step c1) is carried out in the presence of water at neutral, basic or acidic pH. Process according to any one of claims 1 to 10, characterized in that step c2) is carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps. Process according to any one of claims 1 to 11, in which the synthesis gas produced in step e) is (i) treated in a purification unit, (ii) treated in a Fischer-Tropsch process, (iii) used as fuel, and / or (iv) used in a unit for the production of alcohol by fermentation or catalytic route.

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