PROCESS FOR PURIFYING A PYROLYSIS OIL FOR ITS VALORIZATION BY STEAM CRACKLING

Abstract

The invention relates to a process for purifying pyrolysis oil obtained from the pyrolysis of waste including plastics by liquid / liquid extraction. This extraction is carried out using a polar solvent immiscible with the pyrolysis oil, for which a recovery rate greater than or equal to 0.95 is obtained, this recovery rate being 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 pyrolysis oil, recovered after stirring and then decanting a mixture of one part by volume of solvent with twenty-five parts by volume of the pyrolysis oil at atmospheric pressure and at a temperature of 20°C.

Description

Title of the invention: METHOD FOR PURIFYING A PYROLYSIS OIL FOR THE PURPOSE OF ITS VALORIZATION BY STEAM CRACKLING Scope of the invention

[0001] The invention relates to the recovery of oils obtained from the pyrolysis of waste, particularly as a feedstock in a steam cracking process. The process according to the invention makes it possible, in particular, to purify pyrolysis oil from plastic waste of all kinds, regardless of its origin. This plastic waste may contain, in varying proportions, other types of waste such as, for example, lignocellulosic biomass and / or elastomers. Previous art

[0002] Pyrolysis is an endothermic decomposition process in a reducing atmosphere (an oxygen-deprived or oxygen-poor atmosphere, or an atmosphere of inert gases) under the influence of heat (from 300°C). This process allows the decomposition of solid organic matter into three phases: solid (pyrolysis coke or char), liquid (consisting of heavy condensates, pyrolysis oils or tars, or light condensates, H2O), and gaseous (CO, H2, CO2, olefins, and short paraffins). This solid organic matter can include plastics, biomass, agricultural waste, and household waste. With the increasing volume of waste, pyrolysis makes it possible to consider recovering value from this waste by converting it into liquid products that can then be processed to produce high-value-added products.

[0003] Liquid pyrolysis products, also called pyrolysis oils, can, however, contain high levels of undesirable compounds, particularly when used as feedstock in a steam cracking process. These undesirable compounds (or contaminants) include heteroatoms, especially oxygen, nitrogen, and sulfur, but also halogens and transition metals. Other undesirable compounds include unsaturated hydrocarbon compounds, particularly aromatics and dienes.

[0004] Document WO2020 / 212315 describes a process for recovering aliphatic hydrocarbons from a liquid product of the pyrolysis of plastic waste, in particular a mixture of plastics. This liquid product is subjected to solvent extraction to obtain a raffinate with a reduced content of aromatic hydrocarbons and / or polar compounds compared to the liquid product. These polar compounds are organic compounds containing heteroatoms (N, S, O) or salts that may include a cation, such as the ammonium cation, or a metal cation. an alkali metal, an alkaline earth element cation, a transition metal cation, and an anion, such as a carboxylate, sulfate, phosphate, or halide ion. The raffinate resulting from the liquid-liquid extraction then undergoes further extraction with water to remove the solvent present in the raffinate, which is resource-intensive.

[0005] Document WO2020 / 178599A1 describes a process for recovering value from a pyrolysis oil obtained from the pyrolysis of plastic or rubber, or a combination thereof. The pyrolysis oil is treated with an extraction solution comprising a polar organic solvent to provide a mixture comprising an extract and a raffinate. The raffinate obtained by this extraction process is a pyrolysis oil with a reduced content of undesirable compounds such as solid residues, olefins, and compounds comprising heteroatoms (sulfur, nitrogen, and halogens). Oxygenated compounds are considered desirable compounds. The recovery solution may further comprise a hydrocarbon fluid (alkanes or alkenes, or a mixture of both) to promote the separation of the raffinate and the extract.

[0006] These documents do not describe the treatment of pyrolysis oils obtained from the pyrolysis of plastic waste mixed with other types of waste. Summary of the invention

[0007] The invention aims to provide a method for purifying pyrolysis oil that significantly reduces the amount of compounds containing heteroatoms, particularly oxygen, nitrogen, sulfur, metals (especially transition metals), and halides initially present in the pyrolysis oil. The invention can also reduce the amount of unsaturated hydrocarbon compounds initially present in the pyrolysis oil, notably aromatic compounds and diolefins.

[0008] A first object of the invention relates to a process for purifying a pyrolysis oil obtained from the pyrolysis of waste containing plastics, comprising the following steps: - the supply of a pyrolysis oil containing saturated and unsaturated hydrocarbon compounds and polar compounds comprising at least one heteroatom selected from oxygen, sulfur, nitrogen, a transition metal, an alkali metal, an alkaline earth metal, a halogen, - contacting the pyrolysis oil with a polar extraction solvent that is immiscible with the pyrolysis oil, - the recovery of an immiscible extract and raffinate, the extract containing the extraction solvent and at least a portion of the polar compounds, and optionally at least a portion of the unsaturated hydrocarbon compounds, initially contained in pyrolysis oil, the raffinate containing treated pyrolysis oil with reduced content of polar compounds and optionally unsaturated hydrocarbon compounds, wherein the polar extraction solvent immiscible with the pyrolysis oil is a solvent for which a recovery rate greater than or equal to 0.95 is obtained, this recovery rate being defined as the ratio of the volume of an extract to the initial volume of solvent, and this extract is a phase containing the solvent, immiscible with the pyrolysis oil, recovered after stirring and then decanting a mixture of one part by volume of solvent with twenty-five parts by volume of pyrolysis oil at atmospheric pressure and at a temperature of 20°C.

[0009] The raffinate obtained by the process according to the invention is thus free or almost free of solvent so that it does not need to undergo another extraction step before use.

[0010] The process according to the invention makes it possible to extract at least 30% w / w, or even at least 40% w / w or at least 50% w / w of all the polar compounds initially contained in the pyrolysis oil, in particular several polar compounds, especially those containing oxygen, sulfur, nitrogen, halogens, in particular chlorine, fluorine and bromine, and metals, in particular transition metals, in particular iron. The process according to the invention can also make it possible to extract at least 10% w / w of unsaturated hydrocarbon compounds.

[0011] The invention also relates to a steam cracking process comprising a steam cracking step of a pyrolysis oil raffinate recovered during the implementation of the process according to the invention.

[0012] This pyrolysis oil raffinate can be pure or diluted, in particular introduced in a mixture with a typical steam cracking feed. Detailed description of the invention

[0013] When describing the invention, the terms used shall be interpreted in accordance with the following definitions, unless the context requires otherwise.

[0014] The terms "comprising" and "includes" as used herein are synonymous with "including," "includes," or "containing," "contains," and are inclusive or non-inclusive and do not exclude additional undescribed method members, elements, or steps. It will be appreciated if the terms "comprising," "includes," and "composed of" as used herein include the terms "composed of," "consists of," and "consists of."

[0015] The description of numeric ranges by limit values ​​includes all integers and, where applicable, fractions included in that range (for example, 1 to 5 may include 1, 2, 3, 4, 5 when referring to, for example, a certain number of elements, and may also include 1.5; 2; 2.75 and 3.80, when referring to, for example, a certain number of elements, and may also include 1.5; 2; 2.75 and 3.80, when referring to, for example, a certain number of elements, a certain number of elements, and a certain number of elements, ... (e.g., measurements). The description of numeric ranges also includes the limit values ​​themselves (e.g., 1.0 to 5.0 includes both 1.0 and 5.0). Any numeric range mentioned in this document is intended to include all subranges contained within it.

[0016] The features and embodiments of the present invention are described below. Each feature and embodiment of the invention thus defined may be combined with any other feature and / or embodiment, unless otherwise stated. In particular, any feature indicated as preferred or advantageous may be combined with any other feature or embodiment indicated as preferred or advantageous. Pyrolysis oil

[0017] The pyrolysis oil treated in the present invention (and supplied in the first step) is a pyrolysis oil obtained from the pyrolysis of waste including plastics.

[0018] Advantageously, the pyrolysis oil supplied can be a liquid organic phase resulting from the pyrolysis of waste selected from plastics and at least one other waste such as biomass, for example selected from lignocellulosic biomass, paper and cardboard, and / or one or more elastomers.

[0019] This liquid organic phase may be a mixture of liquid organic phases, each organic phase originating from the pyrolysis of one of the aforementioned wastes, or it may be a single liquid organic phase resulting from the pyrolysis of one of the aforementioned wastes or a mixture of two or more of the aforementioned wastes. In other words, the pyrolysis oil treated in the present invention may be a single pyrolysis oil or a mixture of several pyrolysis oils.

[0020] Typically, the liquid organic phase results from the pyrolysis of the aforementioned waste(s) at a temperature of 300 to 1000°C or 400 to 700°C, this pyrolysis being for example a rapid pyrolysis, a flash pyrolysis, or a catalytic pyrolysis or a hydropyrolysis.

[0021] Plastics can be any type of new or used plastic, whether found in household (post-consumer) or industrial waste. Plastics are understood to be materials composed of polymers and optionally of auxiliary components such as plasticizers, fillers, colorants, catalysts, flame retardants, stabilizers, etc. These polymers can be selected from thermosetting and thermoplastic polymers. They are typically polymers or copolymers based on polyolefins, vinyl polymers, styrenic polymers, acrylic polymers, polyamides, polyesters, polyurethanes, polycarbonates, polyethers, epoxy polymers, polyacetals, polyimides, and silicones. In particular, the present invention makes it possible to treat a pyrolysis oil from waste comprising mixtures of two or more of these polymers or copolymers, or to treat mixtures of two or more pyrolysis oils, each oil being derived from the pyrolysis of waste comprising one or more of these polymers or copolymers.

[0022] Typical polymers present in plastics are polystyrene (PS), poly(ethylene terephthalate) (PET), polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polybutylene, poly(butylene terephthalate) (PBT), high and low density polyethylene (PE), halogenated (Cl, F) or not, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), etc., or polymers obtained by polycondensation such as polyamides, polyesters, polyesteramides, etc.

[0023] Elastomers are linear or branched polymers transformed by vulcanization into a weakly cross-linked, infusible, and insoluble three-dimensional network. They include natural or synthetic rubbers. They may 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, acrylonitrile butadiene copolymers (NBR), and polychloroprenes (CR), polyurethanes, silicone elastomers, etc.

[0024] The following table 1 groups together the main characteristics of plastic pyrolysis oils.

[0025] [Tables 1] MIN MAX Density at 15°C kg / m3 750 900 Kinematic viscosity at 40°C mm2 / s 1.0 3.0 Kinematic viscosity at 15°C mm2 / s 2.0 8.0 TAN mgKOH / g <0.1 30 Water content %mass <0.15 0.10 Distillation TBP dist. 5% (±4°) °C 30 160 dist. 50% (±8°) °C 210 320 dist. 95% (±10°) °c 330 530 Composition PONA Paraffins (GC): %m / m 30 55 Olefins (NMR or GC): % m / m 10 (NMR) 50 (NMR) Cyclo-Paraffins (GC): % m / m 10 18 Aromatics (GC): % m / m 5 12 Bromine Index g Br / 100 g 20 60 Maleic anhydride number (**) (ASTM UOP326) mg maleic anhydride / 1g 1 20 CHONS C % m / m 80 90 H % m / m 10 18 0 % m / m 0 8 N ppm 250 3800 S ppm 35 850 Metals + P + Se ICP-AES Al PPm <0.25 15 Ca PPm <0.25 18 Ce ppm <2 <5.00 Co ppm <0.25 <3.00 Cr PPm <0.25 <3.00 Cu PPm <0.25 <3.00 Fe PPm 1 25 K PPm <1 <4.0 Na PPm 2 80 Ni PPm <0.25 <3.00 P PPm 1 66 Sb PPm <0.25 4.00 Se PPm <0.5 <4.0 Si PPm 20 700 Zn PPm nd nd Total PPm 34 900 ICP-MS As PPb 20 Hg PPb <15 Halogens Cl total PPm 50 6000 Br total PPm 10 F total PPm 1.5 10 Potential gum (*) (mg / lOOmL) 5 10000

[0026] GC: gas chromatography

[0027] ICP-MS: Inductively coupled plasma mass spectrometry

[0028] ICP-AES: Inductively coupled plasma atomic emission spectrometry

[0029] (*) measurement by ASTM D873 standard.

[0030] (**) also noted as MAV (for "Maleic Anhydride Value" in English)

[0031] Biomass can be defined as an organic product of plant or animal origin. Biomass thus includes:

[0032] - biomass produced from surplus agricultural land not used for human or animal food: dedicated crops, called energy crops;

[0033] - biomass produced by deforestation (forest maintenance) or clearing of agricultural land;

[0034] - agricultural residues from cereal crops, vines, orchards, olive trees, fruit and vegetables, agri-food residues,...;

[0035] - forest residues from silviculture and wood processing;

[0036] - agricultural residues from livestock farming (manure, slurry, bedding, droppings,...);

[0037] - household organic waste (paper, cardboard, green waste,...);

[0038] - ordinary industrial organic waste (paper, cardboard, wood, waste putrescible,...).

[0039] The pyrolysis oil treated by the invention can come from the pyrolysis of one or more of the aforementioned biomasses, residues and organic wastes.

[0040] Advantageously, the pyrolysis oil treated by the invention can result from the pyrolysis of lignocellulosic biomass, essentially composed of cellulose, hemicellulose, and lignin, for example, wood (hardwoods, softwoods), straw, energy crops (short-rotation coppice (SRC), very short-rotation coppice (VSRC), miscanthus, switchgrass, sorghum, etc.) and forestry or agricultural biomass residues such as bark, wood chips, sawdust, and bagasse. The pyrolysis oils derived from biomass are produced by depolymerization and fragmentation of the constituent elements of the biomass (holocelluloses (cellulose, hemicellulose), lignin), typically under the action of a rapid increase (<2 seconds) in temperature to 450°C–550°C and rapid quenching of the intermediate degradation products. Pyrolysis oils from biomass consist of water (typically 10 to 35% w / w) and a complex mixture of oxygenated compounds.Their elemental composition is close to the composition of the starting biomass, with in particular a high oxygen content (40 to 60% w / w).

[0041] The following table 2 groups together the main characteristics of ligno-cellulosic biomass pyrolysis oils.

[0042] [Tables2] MIN MAX Density at 15°C kg / m³ 1050 1350 Dynamic viscosity at 25°C mPa.s 50 300 Dynamic viscosity at 50°C mPa.s 15 50 TAN mgKOH / g 50.0 300.0 Water content (Karl-Fischer) % by mass 10.00 35.00 Ash content (TGA) % by mass 0.1 2 CHO analysis C % by mass 35.0 60.0 H % by mass 4.0 8.0 0 % by mass 30.0 60.0 Metals + P ICP-AES Al ppm 0 10 Ca ppm 2 50 Cu ppm 1 10 Fe ppm 2 30 K ppm 2 15 Mg ppm 1 10 Na ppm 0 10 Mn Ppm 0 10 Ni PPm 0 5 P PPm 0 7 Si PPm 0 7 Zn PPm 0 5 Total inorganic elements PPm 40 80

[0043] The pyrolysis oil treated by the invention can also result from the pyrolysis of paper and / or cardboard.

[0044] Advantageously, the pyrolysis oil treated in the process according to the invention can be a liquid organic phase resulting from the pyrolysis of waste comprising 50% w / w or more of plastics, optionally from 50% w / w to 99% w / w of plastics, optionally mixed with biomass, an elastomer, or mixtures thereof. This liquid organic phase may originate from the pyrolysis of very different plastics, in other words, from a mixture of two or more of the aforementioned polymers or copolymers.

[0045] Advantageously, the pyrolysis oil can be a liquid organic phase resulting from the pyrolysis of waste, this waste including plastics, in particular in the proportions indicated above, and at least 1%m / m of at least one other waste other than a plastic.

[0046] This other waste material can be selected from an elastomer and biomass, in particular one or more biomasses selected from lignocellulosic biomass, paper, and cardboard. In other words, the treated waste can comprise at least 1% w / w of one or more of these biomass and / or elastomer waste materials, optionally from 1 to 50% w / w, from 2 to 30% w / w, or within a range defined by any two of these limits. Preferably, the waste material(s) added to the plastics are biomass, or the biomass represents at least 50% w / w, 60% w / w, or 80% w / w, preferably at least 90% w / w of the added waste material(s).

[0047] Alternatively, the pyrolysis oil supplied may be a mixture of at least two liquid organic phases resulting from the pyrolysis of waste. It may then comprise 50% w / w or more, optionally from 50% w / w to 99% w, of at least one liquid organic phase resulting from the pyrolysis of plastics, including plastics of all types and / or origins. The pyrolyzed plastics may thus be a mixture of two or more of the aforementioned polymers or copolymers.

[0048] The pyrolysis oil supplied may also be a mixture of at least two liquid organic phases resulting from the pyrolysis of waste, including at least one organic phase resulting from the pyrolysis of plastics, particularly in the proportions indicated above, and at least one organic phase resulting from the pyrolysis of at least one other waste material other than plastic. This other waste material may be selected from an elastomer and biomass, in particular one or more biomass materials, notably lignocellulosic biomass, paper, and cardboard. The pyrolysis oil supplied may then comprise at least 1% w / w of an organic phase resulting from the pyrolysis of one or more of these other waste materials, optionally from 1 to 50% w / w, from 2 to 30% w / w, or within a range defined by any two of these limits.Preferably, the organic phase(s) resulting from the pyrolysis of at least one other waste are organic phases resulting from the pyrolysis of biomass, or comprise at least 50% w / w, 60% w / w or 80% w / w, preferably at least 90% w / w of one or more organic phases resulting from the pyrolysis of biomass.

[0049] Generally, a pyrolysis oil may comprise aliphatic hydrocarbons having a boiling point of 30 to 600°C, in particular aliphatic hydrocarbons comprising cyclic, linear, or branched carbon chains containing 4 to 50 carbon atoms. These aliphatic hydrocarbons may include paraffins and olefins, in particular diolefins, in varying proportions depending on the nature of the pyrolyzed waste and the type of pyrolysis process applied. The pyrolysis oil may also comprise aromatic hydrocarbons.

[0050] A pyrolysis oil may comprise solid matter, typically solid pyrolysis residues (“char”) carried over during the pyrolysis process and / or gums formed from gum precursors present in the pyrolysis oil. The amount of solid matter in a pyrolysis oil may be reduced by one or more solid-liquid separations, for example by filtration or any other suitable technique.

[0051] Before treatment by the process according to the invention, the organic phase(s) resulting from the pyrolysis of one or more of the aforementioned wastes may optionally be pretreated, in particular to reduce their solids and / or water content. By way of example, the solids content of the pyrolysis oil supplied may be at most 2% w / w.

[0052] The pyrolysis oil treated by the process according to the invention includes polar compounds and possibly undesirable unsaturated compounds, particularly for subsequent use of the pyrolysis oil as a feedstock for a steam cracker.

[0053] Unsaturated compounds can be aromatic compounds and diolefins that are precursors of gums. Their presence can lead to instability over time in the pyrolysis oil, with, for example, variations in viscosity and volatility, potential phase separation, and gum formation. Furthermore, the presence of gums causes clogging problems in the equipment.

[0054] Polar compounds comprising heteroatoms can be organic salts, inorganic salts, organic compounds comprising heteroatoms.

[0055] The salts may include a cation selected from the ammonium ion, an alkali metal cation, a transition metal cation or an alkaline earth metal cation, and an anion cation selected from a carboxylate ion, a sulfate ion, a phosphate ion or a halide.

[0056] Organic compounds comprising heteroatoms may include amines, amides, nitriles, esters, ethers, acids, aldehydes, ketones, and alcohols. Organic compounds comprising heteroatoms may be aliphatic or aromatic.

[0057] Typically, amines, amides, nitriles, esters, ethers, acids, halogenated compounds, and silicones are present when the treated waste consists of plastics. Examples of monocyclic aromatic compounds include terephthalic acid and benzoic acid, and an example of a polycyclic compound is poly(ethylene terephthalate) oligomer.

[0058] Typically, acids, aldehydes (including hydroxyaldehydes), ketones (including hydroxyketones), and alcohols (phenols, methanol, ethanol) are present when the treated waste is biomass, particularly lignocellulosic biomass. Extraction solvent

[0059] The extraction solvent is a polar solvent; it may have a density higher or lower than the density of the pyrolysis oil being treated.

[0060] In particular, the density of the extraction solvent may be 3 to 50% higher or lower than that of the pyrolysis oil.

[0061] The extraction solvent is furthermore a solvent that is not miscible in the pyrolysis oil to be purified.

[0062] In the present invention, the extraction solvent (or a mixture of solvents as appropriate) is considered to be 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 initial volume of solvent, this extract being a phase containing the solvent, immiscible with the pyrolysis oil, recovered after stirring and decanting a mixture of one part by volume of solvent with twenty-five parts by volume of the pyrolysis oil to be purified, at atmospheric pressure and at a temperature of 20°C.

[0063] This recovery rate can be determined in particular by following the following procedure: • Introduce 50 mL of pyrolysis oil into a flat-bottom flask with a volume of 100 mL, using a precision pipette of + / -0.5 mL, • Introduce 2 mL of solvent into the flask, using a precision pipette of + / -0.1 mL, • Insert a magnetic rod, close the balloon with a polypropylene stopper, • Stir the mixture on a mechanical stirrer at a speed of 500 rpm for 5 minutes. • At the end of the 5 minutes, stop the stirring, remove the magnetic bar using a magnetic rod, • Transfer the contents of the flask into a graduated tube with an accuracy of + / -0.05 mL for volumes less than or equal to 2 mL and an accuracy of + / -0.1 mL for volumes greater than 2 mL. Wait for the Complete separation is achieved by decantation, and the volume of the two phases is measured using the graduations. Complete separation is considered to have been reached when the volumes of the two phases no longer change.

[0064] The polar solvent may contain one or more heteroatoms, in particular chosen from oxygen, sulfur and nitrogen, preferably oxygen.

[0065] The polar solvent immiscible with the pyrolysis oil to be purified can be chosen from: - Water with an acidic, basic, or neutral pH. An acidic pH can be obtained by adding one or more organic or inorganic acids. Examples of usable organic acids include citric acid (C6H8O7), formic acid (CH2O2), acetic acid (CH3COOH), and sulfamic acid (H3NSO3). Examples of inorganic acids are hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and phosphoric acid (H3PO4). A basic pH can be obtained by adding alkali and alkaline earth metal oxides, alkali and alkaline earth hydroxides (e.g., NaOH, KOH, Ca(OH)2), and amines (e.g., triethylamine, ethylenediamine, ammonia). - glycol ethers, including in particular polyethylene glycol with chemical formula HO-(CH2-CH2-O)nH and average mass molar mass of 90 to 800g / mol, for example diethylene glycol and tetraethylene glycol, polypropylene glycol with chemical formula H[OCH(CH3)CH2]nOH and average mass molar mass of 130 to 800g / mol, for example dipropylene glycol and tetrapropylene glycol, - dialkyl formamides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, notably dimethyl formamide (DMF), - dialkyl sulfoxides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, notably dimethyl sulfoxide (DMSO) and sulfolane - compounds comprising a furan ring - cyclic carbonate esters, including those with 3 to 8 or 3 to 4 carbon atoms, notably propylene carbonate and ethylene carbonate.

[0066] One or more of the aforementioned solvents may be used. However, advantageously, only one of the aforementioned solvents may be used as the extraction solvent provided that it is immiscible with the oil to be purified.

[0067] Preferably, the extraction solvent may be a glycol ether, in particular polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH of average mass molar mass of 90 to 800g / mol or polypropylene glycol of chemical formula H[OCH(CH3)CH2]nOH of average mass 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 in mixture, preferably alone.

[0068] In a preferred embodiment, the extraction solvent is chosen from propylene carbonate, ethylene carbonate and polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH of average molar mass of 90 to 800g / mol, alone or in mixture, preferably alone. Liquid-liquid extraction

[0069] The pyrolysis oil and the extraction solvent can be brought into contact by any means known in the prior art.

[0070] For example, pyrolysis oil and extraction solvent can be introduced into tanks, reactors, or mixers commonly used in the industry, and the two components can be mixed. This mixing can involve vigorous agitation of the two components by a mixing device. For example, the two components can be blended together by stirring or shaking. Alternatively, the mixing can be carried out in a chamber in which the pyrolysis oil and extraction solvent flow in opposite directions.

[0071] The contact between the two components can occur more than once. For example, after the pyrolysis oil and the extraction solvent have been contacted for the first time, the two resulting phases can be contacted again, possibly several times. The contact and phase formation steps can be continuous. Thus, the two components can pass through a mixing device before entering a separation chamber in which a first and a second phase, namely a raffinate and an extract, are formed. The contact between the two components can be achieved using a propeller, a counter-current flow circulation device, an agitation device, a Scheibel® column, a KARR® column, a centrifugal extractor, or a mixer-decanter, particularly a two- or three-stage one.

[0072] The pyrolysis oil can be contacted several times with new batches of extraction solvent, in particular with one and the same extraction solvent.

[0073] Thus, in a preferred embodiment, the process may include: -a second contacting step during which the recovered raffinate is brought into contact with a new batch of the same extraction solvent as that used during the first contacting step mentioned, - followed by a second stage of recovering a second immiscible extract and raffinate, Optionally, these two steps are repeated n times on the raffinate recovered during the recovery step of the previous iteration, where n is a non-zero integer. A purified pyrolysis oil, which can subsequently be subjected to a steam cracking process (alone or in a mixture), is then formed from the raffinate of the last iteration performed.

[0074] Hereafter, the term "raffinat" generally refers to the raffinat recovered during the recovery step when the process includes a single contacting and recovery step, or the raffinat recovered during the second recovery step or the raffinat recovered during the last iteration of the contacting and recovery steps.

[0075] For example, the pyrolysis oil can be contacted with a first batch of extraction solvent to obtain a first raffinate and a first extract. After separating the raffinate from the extract, this first raffinate can be contacted with a second batch of extraction solvent to obtain a second raffinate and a second extract. This cycle can be repeated several times with new batches of the same extraction solvent or with different batches of extraction solvents, but preferably with batches of a single solvent, which facilitates the implementation of the process and the recovery of the raffinates.

[0076] In one embodiment, the cycle of contacting the pyrolysis oil and its raffinate with an extraction solvent can be carried out from 1 to 9 times, in particular from 1 to 4 times. When this cycle is repeated from 2 to 9 times, the same extraction solvent or different extraction solvents can be used in each cycle, but preferably one and the same solvent.

[0077] Typically, the pyrolysis oil and the extraction solvent are brought into contact to such an extent as to allow efficient extraction of the pyrolysis oil by the extraction solvent. Since the pyrolysis oil and the extraction solvent are immiscible, those skilled in the art will understand that these solutions are generally mixed intimately until an emulsion forms, which is then allowed to separate into two phases.

[0078] The contact of the pyrolysis oil with the solvent can in particular be carried out for a period ranging from a few seconds to 1 hour.

[0079] This contact can be made at a temperature of 0 to 60°C, preferably from 0° to 40°C, more preferably from 0° to 30°C, in particular without external heating.

[0080] The contact is typically implemented at atmospheric pressure.

[0081] The volume ratio of the extraction solvent to the pyrolysis oil can be 0.05:1 to 5:1, preferably from 0.5:1 to 2:1, for example from 1:1 or within an interval defined by the combination of the aforementioned values.

[0082] The recovery of the two immiscible phases, namely the extract and the raffinate, can be carried out in the usual way, by separation, generally by a physical separation process. This separation generally consists of physically isolating the raffinate, or at least a portion thereof. Thus, this separation generally consists of separating at least a portion of the raffinate from the extract.

[0083] Due to their immiscibility, the two phases (raffinate and extract) are generally separated in the contacting chamber or may be separated in another chamber. This separation may simply consist of removing (for example by racking or decantation) at least a portion of the extract or raffinate.

[0084] The process according to the invention can in particular make it possible to obtain a rate of removal of heteroatoms contained in polar compounds of 30 to 99%, in particular greater than 40%, this rate of removal being defined, for each element, by equation 1:

[0085] [Equation 1]

[0086] abatement =100.

[0087] Where:

[0088] xH is the content in mg / kg of the element in the pyrolysis oil before treatment,

[0089] xRest is the content in mg / kg of the element in the raffinate.

[0090] The process according to the invention can thus make it possible to obtain one or more of the following abatement rates: - from 30 to 99% for oxygen, - from 50 to 99% for nitrogen, - from 40 to 99% for sulfur, specifically from 50 to 99%, - from 40 to 95% for halogens, including chlorine, bromine, fluorine, - from 10 to 99% for metals, particularly transition metals, in iron in particular.

[0091] Oxygen content can be measured according to the standard: ASTM D5622 / D2504.

[0092] The nitrogen content can be measured according to the standard: ASTM D4629.

[0093] The sulfur content can be measured according to ISO 20846.

[0094] The halogen content can be measured according to the standard: ASTM D7359

[0095] The alkali metal content can be measured according to the standard: ASTM D5708 A or IP 501.

[0096] The alkaline earth metal content can be measured according to the standard: ASTM D5708 Aou IP 501.

[0097] The transition metal content can be measured according to the standard: ASTM D5708 Aou IP 501.

[0098] The versions of the standards cited in this patent application are, where not specified, those in force on January 29, 2021.

[0099] Advantageously, the refiner according to the invention may have at least one of the following characteristics: - an oxygen content of 100 mg / kg or less, - a nitrogen content less than or equal to 75 mg / kg, - a sulfur content of no more than 700 ppm (by mass), - an alkali metal content, particularly K and Na, less than or equal to at 4 mg / kg, - a halogen content less than or equal to 15 mg / kg, in particular a chlorine content less than or equal to Ippm (by mass), - a total metal content of no more than 2 mg / kg.

[0100] The raffinate according to the invention can be subjected to steam cracking, optionally after one or more post-treatments—typically selected from hydrogenation, cracking, and hydrocracking—alone or mixed with other steam cracker feedstocks. In other words, the raffinate can be treated in a steam cracker, either pure or diluted, optionally after the post-treatment mentioned above. Preferably, the post-treatment(s) do not include separation of the raffinate extraction solvent.

[0101] In particular, the raffinate according to the invention may exhibit, after one or more of the aforementioned post-treatments and / or dilution with a typical steam cracker charge, at least one of the typical characteristics of a steam cracker charge, in combination with one or more of the characteristics presented above.

[0102] A typical steam cracker charge has the following characteristics: - an oxygenated compound content less than or equal to 50 ppm (by mass), - an olefin content of less than or equal to 1% vol, - a paraffin content greater than or equal to 65% vol, - the lowest possible aromatic hydrocarbon content in order to limit the formation of coke during subsequent processing of the raffinate.

[0103] The aromatic hydrocarbon content can be determined according to ISO 22854.

[0104] For example, the specifications of a steam cracker charge are defined in the following documents: - AIChE paper number 36d, Feedstock Contaminants in Ethylene Plants - 2017 Update, - Open spec naphtha (OSN) CFR FAR EAST OPEN SPECIFICATION FORM

[0105] NAPHTHA AGREEMENT, 2017 EDITION.

[0106] Steam cracking can be carried out in the usual way, particularly at temperatures of 650° to 1000°C, typically 700 to 900°C or 750 to 850°C. The heated feedstock is introduced into a cracking zone where it undergoes steam cracking under conditions adapted to produce at least olefins and hydrogen. Steam is introduced into the cracking zone to reduce the partial pressure of hydrocarbons and promote olefin production. The steam also reduces the formation and deposition of carbonaceous material, particularly coke, in the cracking zone. Cracking occurs in the absence of oxygen. The residence time in the cracking zone is very short, typically a few milliseconds. Examples

[0107] The charge used is a cut (37-406°C) of a plastic pyrolysis oil (HPP) whose main characteristics are gathered in Table 3.

[0108] [Table 3] Table 3 HPP Pyrolysis Oil Density (kg / m³) 788.0 Chlorine (ppm by mass) 535 Silicon (ppm by mass) 27 Nitrogen (mg / L) 1530 Sulfur (mg / L) 64.7 Oxygen (% by mass) 0.54 Aromatics (% by mass) 7.0 MAY (mg / g) 15.8 Example 1: Miscibility Tests

[0109] Miscibility tests were carried out with three solvents, polyethylene glycol with an average molar mass of 200g / mol (PEG-200), polypropylene carbonate (PC) and N-formylmorpholine (NFM; CAS 4394-85-8), following the protocol below: - In a 100 mL flat-bottomed flask, introduce 50.0 mL of the loading solution using a precision pipette, - Introduce 2.0 mL of solvent using a precision pipette - Insert a magnetic bar, close the balloon with a stopper polypropylene, - Stir the mixture on a magnetic stirrer at a speed of 500 rpm for 5 minutes. - At the end of the 5 minutes, stop the stirring, remove the magnetic bar using a magnetic rod, - Transfer the contents of the flask into a graduated ASTM centrifuge tube. Wait for complete separation and measure the volume of the 2 phases using the graduations.

[0110] The results are summarized in Table 4. [YES] [Table 4] Table 4 PEG-200 PC NFM Solvent Test Temperature Ambient Ambient Ambient Miscibility No / 2 phases No / 2 phases No / 2 phases Solvent (mL) 2.0 2.0 2.0 VHpp (mL) 50.0 50.0 50.0 Vextract (mL) 2.0 2.4 1.8 Recovery Rate 1.00 1.20 0.90

[0112] After contact of the 2 phases, we recover: 100% of PEG 200. - 120% of the PC, which means that part of the charge has dissolved in the solvent. - 90% of the NFM. The remaining 10% are mixed with the feed. Example 2: Liquid / liquid extraction tests

[0113] Liquid / liquid extraction tests were carried out by contacting the plastic pyrolysis oil (HPP) with each of the three solvents (PEG 200, PC, NFM).

[0114] The following protocol was used:

[0115] - contacting the plastic pyrolysis oil (HPP) with the solvent room temperature in a volume ratio HPP / solvent: 50 / 50;

[0116] - stirring at 500 rpm for 5 minutes to ensure good contact between the two phases;

[0117] - separation of phases after 30 minutes of rest.

[0118] The mass yields of raffinate / HPP and extract / solvent are all on the order of 100%. No product loss is observed. The compositions of the raffinates are summarized in Table 5.

[0119] [Table 5] Table 5 HPP product Reffinate 1 Reffinate 2 Reffinate 3 Solvent used for extraction PEG 200 PC NFM Chlorine (ppm by mass) 535 173 133 113 Chlorine removal (%) 68 75 79 Silicon (ppm by mass) 27 24 22 25 Silicon removal (%) 11 18 7 Nitrogen (mg / L) 1530 287.4 281.9 1467 Nitrogen removal (%) 81 82 4 Sulfur (mg / L) 64.7 29.3 24.7 33 Sulfur removal (%) 55 62 49 Oxygen (% by mass) 0.57 0.22 0.31 0.44 Oxygen removal (%) 61 46 19 MAV (mg / g) 15.8 12.4 12.8 11.2 MAV Reduction (%) 22 19 29

[0120] PEG 200 and PC have a solvent recovery rate after liquid / liquid extraction exceeding 95%. Liquid / liquid extraction with PEG 200 allows the extraction of 55% of the sulfur, 70% of the chlorine, 80% of the nitrogen, and 60% of the oxygen contained in a plastic pyrolysis oil. Liquid / liquid extraction with PC allows the extraction of 60% of the sulfur, 75% of the chlorine, 80% of the nitrogen, and 45% of the oxygen contained in a plastic pyrolysis oil.

[0121] NFM has a solvent recovery rate of less than 95% after liquid / liquid extraction. While chlorinated and sulfur species are removed in proportions comparable to those observed with PEG 200 and PC, the results show lower oxygen and nitrogen removal capacities.

Claims

1. Demands Steam cracking process comprising a steam cracking step of a pure or diluted pyrolysis oil raffinate, said pyrolysis oil raffinate being recovered by implementing a purification process of a pyrolysis oil obtained from the pyrolysis of waste containing plastics, said purification process comprising: - the supply of a pyrolysis oil containing saturated and unsaturated hydrocarbon compounds and polar compounds comprising at least one heteroatom selected from oxygen, sulfur, nitrogen, a transition metal, an alkali metal, an alkaline earth metal, a halogen, the pyrolysis oil supplied being a liquid organic phase or a mixture of liquid organic phases resulting from the pyrolysis of waste selected from plastics and at least one other waste which is biomass, optionally mixed with a waste which is an elastomer,- contacting the pyrolysis oil with a polar extraction solvent immiscible with the pyrolysis oil, - recovering an immiscible extract and raffinate, the extract containing the extraction solvent and at least some of the polar compounds, and optionally at least some of the unsaturated hydrocarbon compounds, initially contained in the pyrolysis oil, the raffinate containing a treated pyrolysis oil with a reduced content of polar compounds and optionally unsaturated hydrocarbon compounds, wherein the polar extraction solvent immiscible with the pyrolysis oil is selected from water having an acidic, basic or neutral pH, glycol ethers, dialkyl formamides in which the alkyl group comprises from 1 to 8 carbon atoms, dialkyl sulfoxides in which the alkyl group comprises from 1 to 8 carbon atoms, compounds comprising a furan ring,Cyclic carbonate esters comprising 3 to 8 carbon atoms, and mixtures thereof, and is a solvent for which a recovery rate greater than or equal to 0.95 is obtained, this recovery rate being defined as the ratio of the volume of an extract to a volume of initial solvent, and this extract is a phase containing the solvent, immiscible with pyrolysis oil, recovered after stirring and then decanting a mixture of one part per volume of solvent, with twenty-five parts by volume of pyrolysis oil at atmospheric pressure and at a temperature of 20°C.

2. A process according to claim 1, characterized in that the pyrolysis oil supplied is a liquid organic phase resulting from the pyrolysis of waste comprising 50%m to 99%m of plastics.

3. A process according to claim 2, characterized in that the pyrolysis oil supplied is a liquid organic phase resulting from the pyrolysis of waste comprising at least 1% w / w, optionally from 1 to 50% w / w of at least one other waste which is biomass and optionally an elastomer, optionally a biomass selected from lignocellulosic biomass, paper and cardboard.

4. A process according to claim 1, characterized in that the pyrolysis oil supplied is a mixture of at least two liquid organic phases resulting from the pyrolysis of waste and comprises from 50%m to 99%m of at least one liquid organic phase resulting from the pyrolysis of plastics.

5. A process according to claim 4, characterized in that the pyrolysis oil supplied is a mixture of at least one organic phase resulting from the pyrolysis of plastics and at least one organic phase resulting from the pyrolysis of at least one other waste which is a biomass and optionally an elastomer, optionally a biomass selected from lignocellulosic biomass, paper and cardboard, and comprises at least 1% w / w, optionally from 1 to 50% w / w, of an organic phase resulting from the pyrolysis of said at least one other waste.

6. A process according to any one of claims 1 to 5, wherein the polar extraction solvent is selected from propylene carbonate, ethylene carbonate, polyethylene glycol of chemical formula HO-(CH2-CH2-O)nH of mass average molar mass of 90 to 800g / mol, polypropylene glycol of chemical formula H[OCH(CH3)CH2]nOH of mass average molar mass of 130 to 800g / mol and mixtures thereof.

7. A process according to any one of claims 1 to 6, wherein the purification process comprises: - a second contacting step in which the recovered raffinate is contacted with a new batch of the same extraction solvent as that used in the first contacting step mentioned, - followed by a second step of recovering a second extract and a second immiscible raffinate, optionally, we repeat n times these two steps on the raffinate recovered during the recovery step of the previous iteration, where n is a non-zero integer.