METHOD FOR THE PURIFICATION OF A PLASTIC LIQUEFACTION OIL COMPOSITION IN A TURBULENT FLOW, AND USE THEREOF

- TotalEnergies OneTech

Method for purifying a composition comprising a plastic liquefaction oil, comprising: a) providing a composition comprising a plastic liquefaction oil containing at least 20 ppm by mass of heteroatoms, b) putting said composition in contact with an aqueous medium with a pH above 7, the putting in contact being implemented in turbulent regime having a Reynolds number higher than 2000 and at a temperature of less than or equal to 250° C. to obtain an effluent containing the modified composition, c) subjecting the effluent from step (b) to (c1) a washing in the presence of water or of a solvent that is not miscible with the purified composition, (c2) a separation, or to the succession of steps (c2) and (c1), and obtaining a purified composition having a reduced heteroatom content, and a phase containing the basic compound containing the basic com-pound and heteroatoms initially contained in the modified composition.

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Description
FIELD OF THE INVENTION

The present invention relates to a method for purifying, in turbulent regime, a composition comprising a plastic liquefaction oil and subsequent use thereof in refining and petrochemical methods. The method according to the invention makes it possible in particular to reduce the concentration of heteroatoms in feedstocks coming from plastic waste, in particular with a view to use thereof in a steam cracking method.

PRIOR ART

Plastic waste is usually directed to landfill or incinerated, and a smaller proportion is directed to recycling. There is however a great need, encouraged by the regulations, to limit plastic waste in landfill. Moreover, eliminating plastic waste in landfill is becoming more and more difficult. It is therefore necessary to recycle plastic waste.

One possible method for recycling plastics material is liquefying the plastics material by pyrolysis or hydrothermal liquefaction. However, the plastic oil obtained generally contains large quantities of dienes and heteroatoms, including metals. These numerous heteroatoms and metals are contaminants for the catalysts of the hydrotreatment methods normally used for recycling plastics materials. Furthermore, dienes easily react forming gums. Dienes are also precursors of coke in a steam cracker. It is therefore necessary to treat the plastic liquefaction oils to be able to recycle them. There are numerous treatment methods making it possible to reduce the heteroatom content of plastic liquefaction oils.

The patent application WO 2020/020769 claims a chain of methods for purifying a composition comprising at least 20 ppm of chlorine. Numerous recyclable liquid wastes can be treated, including plastic pyrolysis oils. The chain of methods comprises a heat 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 with respect to the feedstock, followed by a hydrotreatment in order to obtain a new reduction of at least 50% of the chlorine content.

The patent application WO 2021/105326 claims a method for reprocessing liquefied plastic waste comprising a step of pre-treatment of the liquefied plastic waste by putting in contact with an aqueous medium having a pH of at least 7 at a temperature of 200° C. or more, followed by a liquid-liquid separation wherein the aqueous phase is separated from the organic phase, to produce a pre-treated plastics material from liquefied waste. The solution proposed comprises the use of a solution of NaOH in water. The separation of the aqueous and organic phases is implemented by physical methods (centrifugation) or chemical methods (adding separation-aid additives, for example non-aqueous solvents, adding an additional quantity of the aqueous medium used for putting in contact or of an aqueous medium having a different concentration of alkaline substance), or by gravity.

The patent application US 2014/0109465 claims a method for upgrading a hydrocarbon feedstock such as a bituminous sand, a crude petroleum, hydrocarbon refinery effluents, synthetic hydrocarbons, pyrolysis oils, renewable oils, etc., into upgraded hydrocarbon products having lower viscosity, lower density, a lower sulfur content and a lower mineral/metal content. After having been mixed with water, the feedstock is introduced into a high-throughput reactor having a Reynolds number of between 200 and 100,000, and subjected to a high pressure (1500 and 6000 psig), and high temperature (400 and 700° C.) with a residence time of less than 3 minutes, to be converted therein by cracking, isomerization, cyclization, reforming, decarboxylation and dehydration into a hydrocarbon product with added value. This document does not describe purification of the treated feedstocks.

The patent application U.S. Pat. No. 10,071,322 claims a hydrothermal cleaning method and system for the rapid hydrolysis of renewable oils and the reduction of inorganic and organic contaminants. The method describes putting renewable oils in contact with an aqueous medium and then introducing this mixture into a hydrothermal reactor in which the mixture is subjected to high temperatures of between 300 and 500° C., high pressures of between 34 and 414 bar and turbulent flow conditions that do not cause conversion of the feedstock. Turbulent flow in the hydrothermal reactor corresponds to a Reynolds number (Re) of at least 2000. The treatment described in this document requires high temperatures.

The majority of existing purification treatments are implemented at relatively high temperatures. Furthermore, these treatments do not have means for reducing the proportion of silicon or alkali/alkaline-earth metals present in the plastic liquefaction oil after pretreatment by a base. However, it is known that the presence of alkali/alkaline-earth metals can cause deactivation of catalysts used in the catalytic methods for recycling purified plastic liquefaction oil.

There is therefore a need for improving the existing purification methods.

SUMMARY OF THE INVENTION

The invention aims to propose a method for purifying plastic liquefaction oil facilitating purification thereof, in particular by limiting the implementation temperature while maintaining high performances in reducing heteroatoms, and in particular silicon, including for reducing the proportion of alkali and/or alkaline-earth metals resulting from the treatment of the plastic liquefaction oil by a basic compound containing for example an alkali or alkaline-earth metal.

For this purpose, the invention relates to a method for purifying the heteroatom concentration 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) putting said composition in contact with an aqueous medium with a pH above 7, the putting in contact being implemented in turbulent regime having a Reynolds number higher than 2000 and at a temperature of less than or equal to 250° C. to obtain an effluent containing the modified composition,
    • c) subjecting the effluent from step (b) to (c1) a washing in the presence of water or of a solvent that is not miscible with the purified composition, (c2) a separation, or to the succession of steps (c2) and (c1), and obtaining a purified composition having a reduced heteroatom content, and a phase containing the basic compound and heteroatoms initially contained in the modified composition.

Step (b) of the present invention is a treatment implemented in turbulent regime, in particular in co-current mode or continuously, in the presence of an aqueous medium with a pH above 7, to allow elimination of the impurities containing heteroatoms, in particular alkali metals, alkaline-earth metals, silicon, chlorine, bromine, iron, aluminum and others, liable to damage the catalyst of a subsequent hydrotreatment step.

Treatment in turbulent regime makes it possible:

    • to transfer the impurities present in the composition to be treated to an aqueous phase that is not miscible with the composition, the aqueous phase with a concentration of impurities then being able to be separated, and/or
    • favoring reactions between the basic aqueous medium and the composition containing heteroatoms by virtue of better contact between the oil to be treated and the basic aqueous solution. The impurities can next be eliminated by washing with a solvent that is not miscible with the composition and/or by separation of a phase that is not miscible with the composition containing the impurities.

Step (b) according to the invention can be implemented by circulating said composition and the aqueous medium inside at least one tube equipped with at least one internal element able to generate a turbulent regime.

Prior to step b) or during step (b), it is possible to add to an aqueous medium a basic compound in a sufficient quantity for the aqueous medium to have a pH above 7. Preferably, an aqueous compound can be added in a sufficient quantity for the aqueous medium to have a pH above 10 or above 12, more preferably a pH of at least 12.5.

Advantageously, the basic compound can be added in a sufficient quantity to saturate the aqueous medium.

The basic compound of step (b) can comprise an oxide, a hydroxide, a bicarbonate, or an alcoholate of an alkali metal cation or of an alkaline-earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or in a mixture.

Advantageously, the basic compound of step (b) can be selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, EtONa, MeONa, TEAOH, TBuOH, TMAOH, and mixtures thereof.

Step (c) according to the invention can comprise one or more of the following features:

    • step (c) is preceded 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.
    • step c1) is implemented in the presence of water with a neutral or acidic pH or in the presence of an organic solvent that is not miscible with the composition, preferably in the presence of water.
    • step c2) is implemented by (i) centrifugation, (ii) decantation, (iii) hydrocyclone, or (iv) a combination of two or three of these steps.
    • step (c) comprises at least one separation step (c2) for separating the phase containing the basic compound and heteroatoms, and the purified composition, and the phase containing the basic compound and heteroatoms is sent wholly or partly to step (b).

Advantageously, prior to the treatment of step (b), said composition can be subjected to (i) a filtration, (ii) washing with water or a polar solvent that is not miscible with the composition, (iii) a distillation, (iv) a decantation, or (v) to the combination of two, three or four of steps (i) to (iv).

Advantageously, (d) the purified composition of step (c) can undergo a catalytic hydrotreatment, namely a catalytic treatment under hydrogen, in one or two steps to provide a hydrotreated purified composition.

The hydrotreatment of step (d):

    • can be implemented in a single step in which the purified composition of step (c) is hydrotreated at a temperature of 200 to 450° C., preferably from 200 to 340° C. in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a hydrotreatment catalyst, or
    • can be implemented in a first step (d-1) wherein the purified composition of step (c) is hydrotreated, preferably selectively hydrogenated, at a temperature of 80 to 250° C., preferably from 130 to 250° C. in the presence of hydrogen at an absolute pressure of 5 to 60 bar, preferably from 20 to 45 bar and in the presence of a first hydrotreatment catalyst, and in a second step (d-2) wherein the effluent resulting from step (d-1) is hydrotreated at a temperature of 200 to 450° C., preferably from 250 to 340° C. in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a second hydrotreatment catalyst.

Advantageously, the purified and hydrotreated composition emerging from step (d) can furthermore be washed with water to eliminate the inorganic compounds such as hydrosulfide, hydrogen chloride, or ammonia.

Advantageously, the purified composition of step (c) or the hydrotreated purified composition of step (d) can be:

    • (f) used as it stands or separated into usable flows for preparing fuels and combustibles such as LPG, gasoline, diesel, heavy fuel oil or kerosene, and/or for preparing lubricants and/or base oils,
    • and/or treated, pure or diluted, optionally separated into usable flows, in:
    • (g) a steam cracker for producing olefins, and/or
    • (h) a fluidized-bed catalytic cracker, and/or
    • (i) a hydrocracker, then optionally in a steam cracker, and/or
    • (i) a hydrotreatment reactor, in particular a catalytic hydrogenation reactor.

Preferably, the purified composition of step (c) or the hydrotreated purified composition of step (d) can be subjected, pure or diluted, optionally after separation into usable flows, to a steam-cracking step (e) to produce olefins such as ethylene and propylene, which can next serve to manufacture new polymers by polymerization.

Advantageously, the product coming from the effluent coming from step (c), in particular from the washing step (c1), or the hydrotreated effluent coming from step (d), can be purified by passing over a solid adsorbent in order to reduce the proportion of at least one element from F, CI, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or the proportion of water.

The previously described steps of the method according to the invention can be implemented one after the other without any intermediate step apart from the optional additional steps described.

The invention also relates to equipment, in particular adapted to implement the method according to the invention, comprising an optional pre-treatment section (A), a section (B) for treating in turbulent regime, in particular adapted to implement step b), an optional section (C) for separating solids, a separation section (D), in particular adapted to implement step c), an optional hydrotreatment section (E) and/or an optional section for treatment in a steam cracker (F) and/or an optional section for treatment in a hydrocracker (G) and/or an optional section for treatment in a fluidized-bed catalytic cracker (H) and/or an optional section for treatment in a hydrotreatment reactor (I) and/or an optional section for preparing a fuel, a lubricant or a base oil (J), wherein the various sections are fluidically connected to implement the method according to the invention.

Definitions

The hourly volume velocity (HVV) is defined as the hourly volume of flow of the feedstock per unit catalytic volume and is expressed here in h−1.

The terms “comprising” and “comprises” as used here are synonymous with “including”, “includes” or “contains”, “containing”, and are inclusive or without limits and do not exclude additional features, elements or steps of methods not specified.

The specification of a numeric domain without decimals includes all the integer numbers and, when appropriate, fractions thereof (for example, 1 to 5 can include 1, 2, 3, 4 and 5 when reference is made to a number of elements, and can also include 1.5, 2, 2.75 and 3.80 when reference is made for example to a measurement).

The specification of a decimal also comprises the decimal itself (for example, “from 1.0 to 5.0” includes 1.0 and 5.0). Any range of numerical values recited here also comprises any sub-range of numerical values mentioned above.

The expressions % by weight and % by mass have an equivalent meaning and refer to the proportion of the mass of a product relative to 100 g of a composition comprising it.

Unless indicated to the contrary, the measurements given in parts per million (ppm) are expressed by weight.

“Heteroatom” means any elements of an organic compound different from carbon and hydrogen.

The expression “polar solvent” within the meaning of the present patent application covers all the chemical species, alone or in a mixture, including at least one carbon-hydrogen, carbon-halogen, carbon-chalcogen or carbon-nitrogen covalent bond and having a non-zero dipolar moment. It should be understood that the term “polar solvent” within the meaning of the present definition specifically excludes water.

The term “solvent” includes the aforementioned “polar solvents” and apolar solvents, which comprise for example any type of saturated or unsaturated, linear, branched, cyclic and/or aromatic hydrocarbons such as pentane, cyclohexane, olefins, toluene or xylene and certain other solvents with a zero or on almost zero dipolar moment such as tetrachloromethane or carbon disulfide.

The term “naphtha” refers to the general definition used in the oil and gas industry. In particular, it is a case of a hydrocarbon coming from the distillation of crude oil and the boiling point of which is between 15 and 250° C., in accordance with ASTM D2887. Naphtha contains practically no olefins since the hydrocarbons come from crude oil. It is generally considered that a naphtha has a carbon number between C5 and C11, although the carbon number can in some cases be as much as C15. It is also generally accepted that the density of naphtha is between 0.65 and 0.77 g/mL.

“Liquefaction oil” means an oil coming from a pyrolysis method and/or from a method for the hydrothermal liquefaction of a hydrocarbon feedstock. This hydrocarbon feedstock can comprise plastics materials, biomass and/or elastomers, preferably plastics materials and/or biomass, alone or in a mixture, in particular in the form of waste. A liquefaction oil can be formed from a mixture of two or more liquefaction oils coming from the liquefaction of different hydro-carbon feedstocks.

The pyrolysis method must be understood as a thermal cracking method, typically implemented at a temperature of 300 to 1000° C. or from 400 to 700° C., implemented in the presence or not of catalyst and/or a gas (rapid pyrolysis, flash pyrolysis, catalytic pyrolysis, hydropyrolysis, steam pyrolysis, etc).

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

The expression “plastic liquefaction oil” or “oil resulting from plastic liquefaction” or “plastic-waste liquefaction oil” or “liquefaction oil resulting from the liquefaction of waste containing plastics materials” refers to the hydrocarbon liquid products obtained at the end of a pyrolysis or of a 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 selected from lignocellulosic biomass, paper and cardboard, and/or an elastomer, for example latex, optionally vulcanized, or tires. In a particular embodiment, the thermoplastic and/or thermosetting polymers, alone or in a mixture, and generally in the form of waste, can be subjected to pyrolysis or to hydrothermal liquefaction in a mixture with at least one other feedstock, in particular in the form of waste, such as biomass, for example selected from lignocellulosic biomass, paper and/or cardboard. Preferably, this feedstock does not contain elastomers or contains less than 15% thereof by mass, preferably less than 10% by mass or less than 5% by mass.

The plastics material may be of any type, in particular any type of new or used plastics material, included in domestic (post-consumption) or industrial waste. Plastics materials means the materials consisting of polymers and optionally auxiliary components such as plasticizers, fillers, dyes, catalysts, fire retardants, stabilizers, etc. For example, these polymers may be polyethylene, halogenated polyethylene (CI, F), polypropylene, polystyrene, polybutadiene, polyisoprene, polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS), polybutylene, polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polyvinylidene chloride, a polyester, a polyamide, a polycarbonate, a polyether, a polymer epoxide, a polyacetal, a polyimide, a polyester amide, silicone, etc. In general, it will be possible to use any polymer or mixture of polymers able to produce hydrocarbons by liquefaction, i.e. by pyrolysis and/or hydrothermal liquefaction.

Biomass can be defined as a vegetable or animal organic product. Biomass thus comprises (i) the biomass produced by the surplus of agricultural land not used for human or animal food: dedicated cultivations, referred to as energy cultivations; (ii) the biomass produced by clearance (forest maintenance) or cleaning of agricultural lands; (iii) the agricultural residues resulting from cultivations of cereals, vines, orchards, olive trees, fruits and vegetables, food residues, etc.; (iv) forest residues resulting from forestry and timber conversion; (v) agricultural residues resulting from animal husbandry (dung, manure, litter, droppings, etc.); (vi) domestic organic waste (paper, cardboard, green waste, etc.); (vii) ordinary industrial organic waste (paper, cardboard, wood, putrescible waste, etc.). The liquefaction oil treated by the invention can come from the liquefaction of waste containing at least 1% m/m, optionally from 1 to 50% m/m, from 2 to 30% m/m or in an interval defined by any two of these limits, of one or more of the aforementioned biomasses, residues and organic wastes, and the rest consisting of plastic waste, optionally in a mixture with elastomers, in particular in the form of waste. In one embodiment, the waste does not contain elastomers or contains less than 15% thereof by mass, preferably less than 10% by mass or less than 5% by mass.

Elastomers are linear or branched polymers transformed by vulcanization into an infusible and insoluble lightly cross-linked three-dimensional lattice. They include natural or synthetic rubbers. They may form part of waste of the tire type or of any other domestic or industrial waste containing elastomers, natural and/or synthetic rubber, in a mixture or not with other components, such as plastics materials, plasticizers, fillers, vulcanization agents, vulcanization accelerators, additives, etc. Examples of elastomer polymers include ethylene-propylene copolymers, the ethylene-propylene-diene terpolymer (EPDM), polyisoprene (natural or synthetic), polybutadiene, styrene-butadiene copolymers, polymers based on isobutene, isobutylene isoprene copolymers, chlorinated or brominated, acrylonitrile-butadiene copolymers (NBR), and polychloroprenes (CR), polyurethanes, silicone elastomers, etc. The plastic liquefaction oil treated by the invention can come from the liquefaction of waste containing at least 1% m/m, optionally from 1 to 50% m/m, from 2 to 30% m/m or in an interval defined by any two of these limits, of one or more of the aforementioned elastomers, in particular in the form of wastes, the remainder consisting of plastic wastes, optionally in a mixture with biomasses, residues and organic wastes.

The expression “MAV” (the acronym of “Maleic Anhydride Value”) refers to the UOP326-82 method that is expressed in mg of maleic anhydride that reacts with 1 g of sample to be measured.

The expression “bromine number” corresponds to the quantity of bromine in grams that has reacted on 100 g of sample and can be measured in accordance with the ASTM D1159-07 method.

The expression “bromine index” is the number of milligrams of bromine that react with 100 g of sample and can be measured in accordance with the ASTM D2710 or ASTM D5776 methods.

The boiling points as mentioned here are measured at atmospheric pressure, unless specified otherwise. 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 that can be reached during a distillation. At this temperature, no more vapor can be transported to a condenser. Determining the initial and final points has recourse to techniques known in the art and several methods adapted according to the distillation temperature domain are applicable, for example NF EN 15199-1 (version 2020) or ASTM D2887 for measuring boiling points of petroleum fractions by gas chromatography, ASTM D7169 for heavy hydrocarbons, ASTM D7500, D86 or D1160 for distillates.

The concentration of metals in the hydrocarbon matrices can be determined by any known method. Acceptable methods include X-ray fluorescence (XRF), inductive coupling plasma mass spectrometry (ICP-MS) and inductive coupling plasma atomic emission spectrometry (ICP-AES). Specialists in analytical sciences are able to identify the method most adapted to measuring each metal and in general each heteroelement according to the hydrocarbon matrix in question. The oxygen content can be measured in accordance with the standard: ASTM D5622-17/D2504-88(2015). The nitrogen content can be measured in accordance with the standard: ASTM D4629-17. The sulfur content can be measured in accordance with ISO 20846:2011. The halogen content, in particular chlorine, bromine, fluorine, can be measured in accordance with the standard: ASTM D7359-18.

“Hydrotreatment” means any method during which hydrocarbons react with dihydrogen, typically under pressure, in the presence of a catalyst or not. The hydrotreatment can thus comprise one or more reactions selected from hydrodesulfuration (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrodemetallation (HCM), hydrocracking, hydroisomerization and hydrogenation (hydrogenation of the unsaturated compounds into saturated compounds). “Hydrotreatment catalyst” means a catalyst favoring the incorporation of hydrogen in the products. This type of catalyst is typically a metal catalyst comprising one or more metals in groups 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 of the periodic table.

The particular features, structures, properties and embodiments of the invention can be combined freely in one or more embodiments not specifically described here, as will be apparent to specialists in treating plastic liquefaction oils using their general knowledge.

DETAILED DESCRIPTION OF THE INVENTION Description of the Composition Comprising a Plastic Liquefaction Oil

The composition provided at step (a) comprises a plastic liquefaction oil.

In a preferred embodiment, the composition can comprise solely a plastic liquefaction oil.

Alternatively, the composition can comprise at least 1% m plastic liquefaction oil. The rest can then be composed of no more than 99% by mass a diluent or solvent such as a hydrocarbon and/or one or more of the compounds listed below, preferably a component coming from biomass, biomass waste and/or elastomer waste. Preferably, the composition does not comprise a component coming from elastomer waste or in a proportion of less than 15% m or 10% m or 5% m.

In one embodiment, the composition can comprise at least 5% m, preferably 10% m, more preferably at least 25% m, even more preferably at least 50% by mass, more preferably 75% by mass, even more preferably at least 90% by mass plastic liquefaction oil. The composition may comprise no more than 80% m or 90% m or 95% m or 100% m plastic liquefaction oil. The proportion by mass of plastic liquefaction oil(s) in the composition can lie in any interval defined by two of the previously fixed limits.

The composition can furthermore comprise a component coming from biomass, biomass waste and/or elastomer waste, such as a tall oil, a waste food oil, an animal fat, a vegetable oil such as a colza, canola, castor, palm or soya oil, an oil extracted from an alga, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, an oil from liquefaction of biomass, in particular a biomass liquefaction oil such as Panicum virgatum or a lignocellulosic biomass liquefaction oil, for example a wood, paper and/or cardboard liquefaction oil, an oil obtained by liquefaction of ground used furniture, an oil from liquefaction of elastomers, for example latex, optionally vulcanized, or tires, as well as mixtures thereof.

The composition can furthermore comprise a component that is a diluent miscible with the plastic liquefaction oil. This diluent preferably has a diene index of no more than 0.5 g l2/100 g, measured in accordance with UOP 326-17, and a bromine index of no more than 5 g Br2/100 g, measured in accordance with ASTM D1159. The diluent is preferably selected from a naphtha and/or a paraffinic solvent and/or a diesel or a direct distillation gas oil, containing no more than 1% by weight sulfur, preferably no more than 0.1% by weight sulfur, and/or a flow of hydrocarbons having a boiling range of between 50° C. and 150° C. or a boiling range of between 150° C. and 250° C. or a boiling range of between 200° C. and 350° C., preferably having a bromine index of no more than 5 g Br2/100 g and/or a diene index of no more than 0.5 g l2/100g or any combination thereof.

The composition can have a bromine index of no more than 150 g Br2/100 g, preferably no more than 100 g Br2/100 g, even more preferably no more than 80 g Br2/100 g, the most preferred being no more than 50 g Br2/100 g, as measured in accordance with ASTM D1159.

The composition can have a heteroatom content of at least 20 ppm.

The step (a) of providing the composition can comprise:

    • (a1) a step of liquefying waste containing plastics materials 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,
    • (a3) an optional step of mixing the plastic liquefaction oil with a diluent or a solvent.

The liquefaction step (a1) can comprise a pyrolysis step typically implemented at a temperature of 300 to 1000° C. or of 400 to 700° C., this pyrolysis being for example a rapid pyrolysis or a flash pyrolysis or a catalytic pyrolysis or a hydropyrolysis.

Alternatively or in combination, the liquefaction step (a1) can comprise a hydrothermal liquefaction step, typically implemented at a temperature of 250 to 500° C. and at pressures of 10 to 25-40 MPa.

The waste treated at step (a1) can be plastic waste optionally mixed with biomass and/or with elastomers, as previously described, preferably mixed solely with biomass (or with biomass waste), or containing no more than 15% m elastomer waste, preferably no more than 10% m or no more than 5% m.

The separation step (a2) makes it possible to eliminate the gaseous phase, essentially C1-C4 hydrocarbons, and the solid phase (typically char) so as to recover only the liquid organic phase forming a liquefaction oil.

Plastic liquefaction oils contain in particular paraffins, i-paraffins (isoparaffins), dienes, alkynes, olefins, naphthenes and aromatics. Plastic liquefaction oils also contain impurities containing heteroatoms, such as chlorinated, oxygenated, sulfuretted, nitrogenous and/or silylated organic compounds, metals, salts, phosphorus compounds.

The composition of the plastic liquefaction oil is dependent on the nature of the liquefied plastic, and optionally any other waste liquefied with the plastic, and mainly (in particular to more than 80% m/m, usually to more than 90% m/m) consists of hydrocarbons having from 1 to 150 carbon atoms and impurities.

A plastic liquefaction oil typically comprises from 5 to 80% m/m paraffins (including cycloparaffins), from 10 to 95% m/m unsaturated compounds (comprising olefins, dienes and acetylenes), and from 5 to 70% m/m aromatics. These proportions can be determined by gas chromatography.

In particular, a plastic liquefaction oil can comprise a bromine number of 10 to 130 g Br/100 g as measured in accordance with ASTM D1159, and/or a maleic anhydride index (UOP326-82) of 1 to 55 mg of maleic anhydride/1 g.

In a preferred embodiment, said plastic liquefaction oil has an initial boiling point of at least 15° C., and a final boiling point of no more than 800° C., preferably no more than 600° C., even more preferably no more than 560° C., more preferably no more than 450° C., even more preferably no more than 350° C., preferably 250° C. (measured in accordance with NF EN 15199-1/2).

A plastic liquefaction oil typically comprises at least 20 ppm of heteroatoms, or even at least 30 ppm of heteroatoms.

A plastic liquefaction oil can in particular comprise one or more of the following heteroatom contents: from 0 to 8% m/m oxygen (measured in accordance with ASTM D5622), from 1 to 13,000 ppm of nitrogen (measured in accordance with ASTM D4629), from 2 to 10,000 ppm of sulfur (measured in accordance with ISO 20846) from 1 to 10,000 ppm of metals (measured by ICP), from 50 to 6000 ppm of chlorine (measured in accordance with ASTM D7359-18), from 0 to 200 ppm of bromine (measured in accordance with ASTM D7359-18), from 1 to 40 ppm of fluorine (measured in accordance with ASTM D7359-18), 1 to 2000 ppm of silicon (measured by XRF).

Detailed Description of the Optional Step of Pre-Treating the Composition

Between step (a) and (b), the invention can also comprise an optional pre-treatment step, wherein said composition is subjected, in particular immediately before step (b) or (c2), to (i) a filtration, (ii) washing with water or a polar solvent that is not miscible with the composition, (iii) a distillation, (iv) a decantation, or (v) to the combination of two, three or four of steps (i) to (iv). This additional step can make it possible to reduce some of the impurities contained in the composition such as oxygen, nitrogen, chlorine, sulfur or other heteroatoms. In particular, reducing the quantity of oxygen can make it possible to avoid the formation of solid and/or gels during step (c1).

During the additional washing step (ii), the volume ratio of polar solvent or water to composition can 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 à 60/40.

When water is used for the washing (ii), it can have an acid, basic or neutral pH. An acid pH can be obtained by adding one or more organic or inorganic acids. Examples of organic acids that can be used comprise citric acid (C6H8O7), formic acid (CH2O2), and acetic acid (CH3COOH). Examples of inorganic acids are sulfamic acid (H3NSO3), 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, alkaline and alkaline-earth metal hydroxides (for example NaOH, KOH, Ca(OH)2), alkaline and alkaline-earth metal bicarbonates, and amines (for example triethylamine, ethylenediamine, ammonia),

The polar solvent can have a density greater than or less than the density of the composition comprising a plastic liquefaction oil.

In particular, the density of the polar solvent can be 3 to 50% greater than or less than that of the composition.

The polar solvent is a solvent that is not miscible with the composition comprising a plastic liquefaction oil to be purified.

By way of example, it can be considered that the polar solvent (or that a mixture of polar solvents where applicable) is non-miscible 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, not miscible with the composition containing liquefaction oil, recovered after stirring and then decantation of a mixture of one part per volume of solvent with twenty-five parts per volume of the composition containing a liquefaction to be purified, at atmospheric pressure and at a temperature of 20° C.

This recovery rate will in particular be able to be determined in accordance with the following procedure:

    • Introducing 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,
    • Introducing 2 mL of solvent into the flask, using a precision pipette of +/−0.1 mL,
    • Introducing a magnetized bar, closing the flask with a polypropylene stopper,
    • Stirring the mixture on a mechanical stirring plate at a speed of 500 revolutions/min for 5 min.
    • In the end of 5 minutes, stopping the stirring, removing the magnetized bar by means of a magnetized rod,
    • Transferring the contents of the flask into a graduated tube having a precision of +/−0.05 mL for a volume of less than or equal to 2 mL and a precision of +/−0.1 mL for a volume greater than 2 mL. Awaiting complete demixing by decantation and measuring the volume of the 2 phases by means of graduations. It is considered that complete demixing is achieved when the volumes of the two phases no longer vary.

Acceptable non-miscible polar solvents comprise (i) sulfuretted compounds, for example dimethylsulfoxide, (ii) nitrogenous 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—CH213 O)n-H with a mass-average molar mass of 90 to 800 g/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 800 g/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, in particular dimethylformamide (DMF),
    • dialkyl sulfoxides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethylsulfoxide (DMSO) and sulfolane,
    • the 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 aforementioned solvents can be used. However, advantageously, a single one of the aforementioned solvents can be used provided that it is not miscible with the composition containing a liquefaction oil to be purified.

Preferably, the polar solvent may be ethylene glycol or a glycol ether, in particular polyethylene glycol of chemical formula HO—(CH 2—CH2—O)n-H with a mass-average molar mass of 90 to 800 g/mol or polypropylene glycol of chemical formula H[OCH(CH3)CH2]nOH with a mass-average molar mass of 130 to 800 g/mol, or a compound comprising a furan ring, or a cyclic carbonate ester, in particular propylene or ethylene carbonate, alone or in a mixture, preferably alone.

In a preferred embodiment, the polar solvent is selected from propylene carbonate, ethylene carbonate, ethylene glycol and the polyethylene glycol of chemical formula HO—(CH2—CH2—O)n-H with a mass-average molar mass of 90 to 800 g/mol, alone or in a mixture, preferably alone.

Description of the Basic Compound Used in Step (b)

Step (b) is implemented in the presence of an aqueous medium with a pH greater than 7, for example 7.1 up to a pH going as far as saturation of the compound in water, preferably from 8 to 14, more preferably from 9 to 14, or in any interval defined by two of these limits. Preferably, a pH higher than 10 will be selected, for example at least 10.5, or higher than 12, more preferably a pH of at least 12.5.

This basic aqueous medium is typically obtained by adding a basic compound to water, preferably a nucleophilic basic compound.

Advantageously, the quantity of basic compound used is from 0.1 to 50% m, preferably at least 1% m, more preferably at least 3% m, even more preferably at least 5% m or even at least 10% m with respect to the total mass of the composition treated (composition provided by step (a)). For example, the quantity of basic compound used can be from 0.1 to 15% by mass, more preferably with 1 to 15% by mass, more preferably from 1 to 10% by mass, in particular from 1 to 5% by mass, with respect to the total mass of the composition treated (composition provided by step (a)).

The basic compound in solution can be added to the composition provided at step (a) either before step (b) or during step (b). This addition of the basic compound to the composition can optionally be followed by a mixing step before implementing step (b).

The basic compound is thus added to the composition in solubilized form in an aqueous medium, preferably in water.

Advantageously, the basic compound added in solubilized form may be in solution in an aqueous medium, preferably water, and the proportion of basic compound in the aqueous medium may be from 0.1 to 50% by mass, preferably from 15 to 50% by mass, more preferably from 25% to 50% by mass, preferably from 40 to 50% by mass, even more preferably the aqueous medium is saturated with basic compound, in particular the aqueous medium contains a just sufficient quantity of basic compound to obtain a saturated solution. Such a saturated solution can advantageously have a pH higher than 10 or higher than 12, more preferably a pH of at least 12.5.

In one embodiment, the basic compound can comprise an oxide, a hydroxide, a bicarbonate, or an alcoholate of an alkali metal cation or of an alkaline-earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, for example a cation of tetramethylammonium (TMA+), of tetraethylammonium (TEA+), of tetrapropylammonium (TPA+), or of tetrabutylammonium (TBA+), alone or in a mixture. Preferably, the basic compound can comprise an aforementioned oxide or hydroxide, alone or in a mixture.

In a preferred embodiment, the basic compound can be selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, EtONa, MeONa, TEAOH, TBuOH, TMAOH, and mixtures thereof A preferred basic compound can be selected from NaOH, KOH and mixtures thereof, preferably in solution in water.

Detailed Description of Step (b) of Treatment in Turbulent Regime

During step (b), the composition is treated under conditions effective for generating a turbulent regime, which reinforce the transfer of the impurities contained in the composition to an aqueous phase or an organic phase not miscible with the composition or which modify the impurities sufficiently to allow separation thereof from the composition. In particular, step (b) is implemented under conditions that do not cause conversion of the composition to be treated.

Advantageously, the basic compound added at step (b) is in solution in water, and the proportion of basic compound in the water may be from 0.1 to 50% by mass, preferably from 25% to 50% by mass, more preferably from 40 to 50% by mass, even more preferably the aqueous medium is saturated with basic compound, in particular the aqueous medium contains a just sufficient quantity of basic compound to obtain a saturated solution.

During step (b), the volume ratio of the basic compound in solution in the water/composition, i.e. the volume ratio of the mixture (basic compound+water)/composition, can 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 other interval defined by any two of the aforementioned bounds.

Turbulent regime is obtained when the flow has a Reynolds number of at least 2000, preferably at least 3000, more preferably at least 4000, or even at least 10,000.

Turbulent regime can advantageously be achieved using at least one static mixer. That is to say, the composition and the aqueous medium are introduced into at least one tube equipped with at least one internal element able to generate the turbulent regime having a Reynolds number of at least 2000.

A static mixer is a device for continuous mixing of fluids in co-current mode, it makes it possible to mix fluids without having recourse to moving parts. The static mixer relies on a tubular body for producing the mixing and the required dispersion effects when the fluid flows through the fixed components of the mixer. The fluid is then divided, separated and pushed over the internal elements of the static mixer, causing the radial movement of the fluid outwards, leading to a difference in velocity between the molecules of the fluid, causing mixing of the fluid. In general, the direction of rotation of the fluid changes in each internal element, thus receiving a rapid reversal of the inertia force, which also stirs the fluid. These two principles make it possible to achieve a turbulent regime the Reynolds number of which is at least 2000. The internal element may be strips in a helix, twisted, perforated with spikes or fins or wire coils.

Step (b) can be implemented at a temperature of no more than 250° C. In a preferred embodiment step (b) can be implemented at a temperature of 80 to 250° C., preferably from 90 to 230° C., more preferably from 100 to 230° C. or in any interval defined by any two of these limits. These temperature ranges can advantageously be combined with the pH ranges and/or with the proportions of basic compound in the aqueous medium as aforementioned in order to improve purification of the oil.

Advantageously, during step (b), the composition provided at step (a) may be preheated, preferably in the presence of the aqueous medium comprising the basic compound, at the implementation temperature of step (b), before being subjected to the turbulent regime.

The step b) of treatment in turbulent regime may in particular be implemented for a period of 1 minute to 2 hours, preferably from 1 minute to 1 hour, more preferably from 1 minute to 20 minutes or from 1 minute to 16 minutes.

The treatment in turbulent regime of step (b) can be implemented at a pressure of 1 to 100 bar, of 5 to 80 bar, preferably of 10 to 60 bar. It is recommended that the composition comprising the liquefaction oil and the basic compound be essentially in liquid phase during the treatment in turbulent regime.

The treatment in turbulent regime of step (b) can be implemented in one, two or several steps, for example by passing the composition to be treated through one or more static mixers, for example put in series and/or in parallel, able to generate a turbulent regime.

The treatment in turbulent regime of step (b) can be implemented in a heat exchanger of the calender-tubes type in which the at least one static mixture is located in at least one tube or in the cluster of tubes disposed inside a casing called a calender.

Step (b) can therefore comprise:

    • pumping the composition to be treated and the basic compound through at least one static mixer. Alternatively, the composition to be treated and the basic compound can be pumped separately and mixed at the inlet of the static mixer,
    • generating characteristics of a turbulent regime to eliminate the impurities.

Step (b) (comprising for example the steps of pumping and generating the turbulent regime) can be repeated one or more times before implementing step (c), either by returning the composition emerging from the reactor to the inlet of the static mixer, or by using a plurality of static mixers in series.

In a variant, step (b) (comprising for example the steps of pumping and generating the turbulent regime) and step (c) can be repeated one or more times, for example returning the purified composition of step (c) to the inlet of step (b) or by using a plurality of units in series able to implement steps (b) and (c) successively.

On emerging from step (b), the composition is thus modified since the impurities (the compounds containing heteroatoms) have been modified by the treatment of step (b). The modified composition obtained on emerging from step (b) makes it possible to subsequently obtain a purified composition comprising a reduced heteroatom content, as explained below.

Detailed Description of the Additional Optional Step of Separating the Solids

Step (c), and in particular one or more of steps (c1) and (c2), can 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) since it can facilitate the separation of the phases by eliminating all or some of the solids present in the effluent coming from step (b).

Detailed Description of Step C)

During step (c), the effluent of step (b) can be subjected to (c1) a washing with water or a solvent not miscible with the modified composition, (c2) a 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 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. It can make it possible to obtain a purified composition having in particular an alkali or alkaline-earth metal content of less than 2 ppm (by mass).

The selection of steps (c1), (c2) or (c2)+(c1) can in particular be selected according to the purification objective sought.

When step (c) implements the separation (c2), it will advantageously be possible to recover the phase containing the basic compound recovered at the discharge from the separation step (c2) and to return it in whole or in part to the hydrodynamic-cavitation treatment step (b). This makes it possible to reduce the quantities of basic compound to be used and thus to reduce the related costs.

Detailed Description of the Washing Step c1)

The washing step (c1) is implemented with water with a neutral, basic or acid pH or with a solvent that is not miscible with the purified position. The washing step (c1) makes it possible to recover a phase containing the purified composition and a phase containing the water or the non-miscible solvent used for washing, the basic compound and the impurities. In other words, at the discharge from the washing step, these phases are recovered separately, for example following a liquid/liquid separation (centrifugation and/or decantation and/or other) implemented at the end of the washing step.

This step (c1) makes it possible to eliminate the impurities containing heteroatoms present in the effluent containing the modified composition emerging from step (b) by solubilizing them in a solvent (water or an organic solvent). It can make it possible to obtain a purified composition having in particular an alkali or alkaline-earth metal content of less than 2 ppm (by mass).

This washing step (c1) can also make it possible to separate the basic compound from the purified composition.

The basic compound used during step (b) being solubilized in an aqueous medium, not miscible with the composition, this washing step (c1) can be omitted.

The water used during step (c1) can have an acid pH (pH<7), basic pH (pH>7) or neutral pH (pH=7).

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

An acid pH can be obtained by adding one or more organic or inorganic acids. Examples are cited with reference to the washing (ii) of the optional pre-treatment step Preferably, the water can have a pH of 0.1 to 6.9.

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

The non-miscible solvent can be any organic solvent not miscible with the composition, in particular in which the impurities containing heteroatoms are soluble. A non-miscible solvent that can be used is for example a polar solvent, in particular those described in the optional pre-treatment step.

Step (c 1) can be implemented at a temperature of 10° C. to 120° C. preferably from 15° C. to 95° C., more preferably from 15° C. to 80° C., or in any interval defined by any two of these limits, advantageously without external heating. Step (c1) is typically implemented at atmospheric pressure or at a pressure close to the pressure at which step (b) is implemented.

Step (c1) can be implemented on the effluent directly coming from step (b), without an intermediate step, or on the effluent containing the purified composition emerging from 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 of impurities containing heteroatoms, still present in the purified composition emerging from step (c2), which can make it possible to obtain a purified composition having in particular an alkali or alkaline-earth metal content of less than or equal to 2 ppm (by mass).

During step (c1), the volume ratio of solvent or water/effluent containing the purified composition can 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 afore-mentioned bounds.

Step (c1) can comprise, or consist of, putting the effluent coming from step (b) or (c2) in contact with the water or a non-miscible solvent by any means known in the prior art.

For example, the effluent coming from step (b) or (c2) and the solvent or water can be introduced into vessels, reactors or mixers normally used in the profession and the two components can be mixed. The putting in contact may comprise vigorous stirring of the two components by a mixing device. For example, the two components can be mixed together by stirring or by shaking. Alternatively, the putting in contact can be implemented in an enclosure in which the two components circulate in countercurrent, for example in contact columns with suitable packing in order to increase the contact between the phase of the composition being treated and the water or a non-miscible solvent. Alternatively, the putting in contact can be implemented in another static mixer in co-current mode or in a cavitation chamber. This putting in contact may occur more than one time, in particular under the conditions presented above.

The washing step (c1) can be implemented continuously or in batch mode.

Detailed Description of the Separation Step c2)

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 is typically a liquid/liquid separation. It can advantageously be implemented by (i) centrifugation, (ii) decantation, (iii) hydrocyclone, or (iv) a combination of two or three of these steps. It can make it possible to obtain a purified composition having in particular an alkali or alkaline-earth metal content of less than 2 ppm (by mass).

Step (c2) can be implemented 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. This step (c2) then separates a phase containing the purified composition and a phase containing the aqueous medium (not miscible with the composition), the basic com-pound and the impurities. 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 at step (b).

Step (c2) can also be implemented on the effluent containing the purified composition obtained at the discharge from step (c1).

Prior to step (c2), the effluent containing the modified composition emerging from step (b) or the effluent containing the purified composition emerging from step (c1) can be treated in at least one mechanical or electrostatic coalescer in order to break up any emulsion and to concentrate the basic compound in the solvent or water.

Step (c 2) can be implemented at a temperature of 10° C. to 120° C., preferably from 15° C. to 95° C., more preferably from 15° C. to 80° C., or in any interval defined by any two of these limits, advantageously without external heating. Step (c2) is typically implemented at atmospheric pressure or at a pressure close to the pressure at which step (b) is implemented.

Detailed Description of the Optional Catalytic Hydrotreatment Step (d)

The hydrotreatment of step (d) can be implemented in a single step or in two steps. When it is implemented in a single step, the effluent resulting from step (c) is typically hydrotreated at a temperature of 200 to 450° C., preferably from 200 to 340° C. in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a hydrotreatment catalyst, for example a catalyst of the NiMo type (0.1-60% by mass) and/or CoMo type (0.1-60% by mass), generally on a support.

Alternatively, the hydrotreatment of step (d) can be implemented in a first step (d-1) wherein the effluent resulting from step (c) 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 between 5 and 60 bar, preferably 20 to 45 bar, 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) wherein the effluent resulting from step (d-1) is hydrogenated at a temperature of 200 to 450° C., preferably from 250 to 340° C., in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a second hydrotreatment catalyst, for example a catalyst of the NiMo type (0.1-60% by weight) and/or CoMo type (0.1-60% by weight). The first step can then make it possible to hydrogenate dienes initially present in the composition.

This step (d) can be implemented in a single reactor with a plurality of catalytic beds put in series with optionally additions of hydrogen between the beds or in a plurality of reactors in series according to the objective sought.

This hydrotreatment step can also have a function of demetallization, cracking or dearomatization according to the characteristics of the catalyst and the hydrotreatment conditions.

Preferably, the purified composition obtained after step (c) is sent to the hydrotreatment step without being cooled and/or depressurized at the temperature and pressure at the output of step (c). The feedstock for hydrotreatment, containing at least part of the purified composition, can advantageously be heated by a heat exchanger that is supplied by the hydrotreatment effluent (given that hydrotreatment is exothermic, the hydrotreatment effluent will have a higher temperature than the feedstock entering the hydrotreatment).

Preferably, the feedstock for hydrotreatment, containing at least part of the purified composition, can be diluted with a part of the hydrotreatment effluent, again having a temperature higher than the temperature required at the entry to 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.

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

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

The adsorbent can be used in regenerative or non-regenerative mode, at a temperature of less than 400° C., preferably less than 100° C., more preferentially less than 60° C., selected from: (i) a silica gel, (ii) a clay, (iii) a pounded clay, (iv) apatite, (v) hydroxyapatite and combinations thereof, (vi) an alumina, for example an alumina obtained by precipitating boehmite, 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 acidic 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) a clay treated by an acid such as Tonsil® from Clariant, (xiii) a molecular sieve in the form of an aluminosilicate containing an alkali or alkaline-earth cation, for example the sieves 3A, 4A, 5A, 13 X, for example mar-keted under the Siliporite® trademark from Ceca, (x iv) a zeolite, (xv) an active 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 at least one element from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg et Hg and/or water.

According to a preferred embodiment, the adsorbent is regenerated, has a specific surface area of at least 200 m2/g and is used in a fixed-bed reactor at less than 100° C. with a VVH of 0.1 to 10 h−1.

The effluent emerging from the hydrotreatment step (d), namely the purified and hydrotreated composition, optionally purified by passing over a solid adsorbent, can be washed with water to eliminate the inorganic compounds such as hydrosulfide, hydrogen chloride, and ammonia before being subjected to subsequent treatments.

The purified composition emerging from step (c) or the effluent emerging from the hydrotreatment step (d) optionally washed with water can be fractionated into usable flows the cut points of which are typically selected according to the subsequent treatment. This fractionation is implemented according to distillation temperature ranges, for example to separate the flows of the LPG, gasoline, diesel, heavy fuel oil and kerosene type, which can then be treated in a steam cracker and/or in a catalytic cracker and/or in a hydrocracker (then optionally in a steam cracker) and/or in a hydrotreatment reactor and/or used as they stand for preparing fuels, combustibles, lubricants or base oils. A person skilled in the art is able to select the cuts most adapted to the subsequent treatment units according to the objective sought.

The purified composition of step (c) or the purified and hydrotreated composition of step (d) can also be used diluted, for example mixed with naphtha, gasoil or crude oil in order to obtain a concentration of purified plastic liquefaction oil ranging from 0.01% by weight to 50% by weight at a maximum; preferably from 0.1% by weight to 25% by weight, even more preferably from 1% by weight to 20% by weight at the input of the following treatment.

Detailed Description of the Optional Steam-Cracking Step (e)

The steam-cracking step (e) can be implemented on the purified composition of step (c) with or without dilution with a conventional steam-cracking feedstock, or on the hydrotreated purified composition of step (d) with or without dilution. Prior to the step (e), a step of separation by distillation can be implemented according to the technology of steam-cracking furnaces.

This step (e) makes it possible to produce olefins such as ethylene and propylene and aromatics. The ethylene and propylene can then advantageously be converted respectively into polyethylene and polypropylene in a polymerization section.

The steam-cracking step (e) consists in thermally cracking, in one or more furnaces, a mixture of the purified composition and/or the purified and hydrotreated composition and steam at high temperatures of the order of 650 to 1000° C., preferably from 700 to 900° C., typically from 750 to 850° C., at low pressures (1 to 3 bar). The cracking reaction is implemented in the absence of oxygen. The reaction time is normally very short, of the order of a few hundreds of milliseconds. These conditions make it possible to break the carbon-carbon bonds and to produce unsaturated hydrocarbons with smaller molecules than the feedstock introduced into the reactor or reactors. The effluents leaving the reactor or reactors are next rapidly cooled to temperatures of 400 to 550° C. in order to limit the secondary reactions of the olefin, diene and acetylene polymerization type. The cooled effluents are finally fractionated to recover the C2-C5 light olefins, such as ethylene, propylene, butadiene, isobutylene, n-butene and isoprene.

The purified composition of step (c) or the hydrotreated purified composition of step (d) can be sent to the steam cracker without dilution. The purified composition of step (c) or the purified and hydrotreated composition of step (d) can also be mixed with naphtha, gas oil or another crude oil cut in order to obtain a concentration of purified plastic liquefaction oil ranging from 0.01% by weight to 50% by weight at a maximum; preferably from 0.1% by weight to 25% by weight, even more preferably from 1% by weight to 20% by weight at the input of the steam cracker The purified composition is next converted into olefins, such as ethylene and propylene, as well as into aromatics.

In a preferred embodiment, the purified, or purified and hydrotreated, composition can be sent at least partially directly into a steam cracker without dilution other than the steam used for steam cracking, and preferably as the only flow sent at least partially into the steam cracker, to produce olefins, such as ethylene and propylene, and aromatics.

The steam cracker is known per se in the art. The feedstock feeding the steam cracker, in addition to the flow obtained by the inventive method, can be ethane, liquefied petroleum gas, naphtha or gas oils. Liquefied petroleum gas (LPG) essentially consists of propane and butanes. Gas oils have a boiling range of approximately 200 to 350° C., and consist of C10 to C22 hydrocarbons, including mainly linear and branched paraffins, cyclic paraffins and aromatics (including mono-, naphtho- and polyaromatics.

In particular, the cracking products obtained at the discharge from the steam cracker can comprise ethylene, propylene and benzene, and optionally hydrogen, toluene, xylenes and 1,3-butadiene.

In a preferred embodiment, the output temperature of the steam cracker can be between 800 and 1200° C., preferably between 820 and 1100° C., more preferably between 830 and 950° C., more preferably between 840 and 920° C. The output temperature can influence the proportion of high-value chemical products in the cracking products obtained by the present method.

In a preferred embodiment, the residence time in the steam cracker, through the radiation section of the reactor where the temperature is between 650 and 1200° C., can be between 0.005 and 0.5 seconds, preferably between 0.01 and 0.4 seconds.

In a preferred embodiment, the steam cracking is implemented in the presence of steam in a ratio of 0.1 to 1.0 kg of steam per kg of hydrocarbon feedstock, preferably 0.25 to 0.7 kg of steam per kg of hydrocarbon feedstock in the steam cracker, preferably in a ratio of 0.35 kg of steam per kg of feedstock mixture, to obtain cracking products as defined above.

In a preferred embodiment, the output pressure of the reactor can be between 500 and 1500 mbar, preferably between 700 and 1000 mbar, more preferably can be approximately 850 mbar. The residence time of the feedstock in the reactor and the temperature must be considered together. A lower operating pressure facilitates the formation of light olefins and reduces the formation of coke. The lowest possible pressure is obtained (i) by maintaining the output pressure of the reactor as close as possible to atmospheric pressure at the suction of the cracking-gas compressor, (ii) by reducing the pressure of the hydrocarbons by dilution with steam (which has a substantial influence on slowing down the formation of coke). The steam/raw material ratio can be maintained at a sufficient level to limit the formation of coke.

Since the purified and/or purified and hydrotreated composition has a wide distribution in terms of carbon number (or boiling points), the vaporization of such a feedstock may be incomplete at the entry to the reactors at the temperature where certain hydrocarbon molecules begin to decompose, the purified and/or purified and hydrotreated composition can then be preheated to a temperature at least 10° C. below the decomposition temperature, and then subjected to a separation of the hydrocarbon vapors produced and of the residual hydrocarbon liquid in a flash vessel. In this flash vessel the liquid emerges downwards by gravity and the hydrocarbon vapors upwards. Optionally, the hydrocarbon liquid can be sent to the plastic liquefaction unit or to the optional hydrocracking step.

Detailed Description of the Optional Hydrocracking Step

Prior to the steam-cracking step (e), the hydrotreated effluent resulting from step (d) can be subjected to a cracking reaction in order to reduce the length of the carbon chains of the paraffins present in the hydrotreated effluent.

Typically, this cracking reaction is a hydrocracking reaction implemented at a temperature of 250 to 480° C., a partial hydrogen pressure of 1.5 to 25 MPa abs. and an hourly volume velocity of 0.1 to 10 h−1.

A hydrocracking catalyst that can be used comprises for example a support selected from halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites and a hydro-dehydrogenating function comprising at least one metal in group VIB selected from chromium, molybdenum, and tungsten, alone or in a mixture, and/or at least one metal in group VIII selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, and platinum.

In one embodiment, the hydrocracking step can be implemented by adding a hydrocracking catalyst bed downstream of the last catalytic bed of the hydrotreatment of the hydrotreatment section.

DESCRIPTION OF FIGURES

FIG. 1 describes a possible embodiment of the invention. In this possible embodiment, the plastic liquefaction oil (1) is first optionally pretreated in the pre-treatment section (A) to be subjected therein to an optional pre-treatment (PTT) by (i) a filtration, (ii) washing with water or a polar solvent, (iii) a distillation, (iv) a decantation, or (v) to the combination of two, three or four of steps (i) to (iv). The pretreated oil (2) is next sent to a section (B) for treatment in turbulent regime in the presence of a basic compound solubilized in water (3) implementing step (b) of the invention. The effluent (4) of step (b) can next be sent to an optional section (C) for separating solids. The effluent (5) emerging from section (C) or the effluent (4) emerging from section (B) is next sent to a separation section (D) implementing step (c) of the present invention. When this section implements step (c2), the phase (9) containing the basic com-pound can be sent to the section (B) for treatment in turbulent regime. The effluent (6) emerging from the section (D) can be sent to one or more of the following optional sections: an optional hydrotreatment (HDT) section (E), an optional section (SC) of treatment in a steam cracker (F), an optional section (HC) of treatment in a hydrocracker (G), an optional section (FCC) of treatment in a fluidized-bed catalytic cracker (H), an optional section (HDT) of treatment in a hydrotreatment reactor (I), an optional section (POOL) of preparing a fuel or a combustible or a lubricant or a base oil (J). The hydrotreatment section can comprise one or more selective hydrotreatment and/or hydrogenation units. Preferably, the effluent (7) emerging from the hydrotreatment section (E) is next steam cracked to obtain olefins, which can then be polymerized. Preferably, the effluent (7) emerging from the hydrocracking section (E) is next steam cracked to obtain olefins, which can then be polymerized.

 EXAMPLES

The embodiments of the present invention are illustrated by the following non-limitative examples.

Example 1: Hydrotreatment in Two Steps and Steam Cracking of a Plastic Liquefaction Oil

A purified plastic liquefaction oil emerging from step (c) of the method according to the invention can be hydrotreated in two steps in accordance with the following procedure:

The purified and washed liquefaction oil can be introduced into a first hydrotreatment section (HDT1), mainly to hydrogenate the diolefins and acetylenes. This step can comprise a plurality of reactors in series and/or parallel if guard reactors are used upstream or downstream of the first hydrogenation reactor. These guard reactors can make it possible to reduce the concentration of certain undesirable chemical species and/or elements such as chlorine, silicon and metals. Particularly undesirable metals include Na, Ca, Mg, Fe, As and Hg.

A second hydrotreatment section (HDT2) is dedicated to the hydrogenation of the olefins and to demetallization (HDM), desulphurization (HDS), denitrogenation (HDN) and deoxygenation (HDO). This section consists of one or more reactors operated in series, in parallel, or both. Isolated guard reactors, in lead-lag, in series and/or in parallel can be envisaged depending on the nature and the quantity of the contaminant in the flow to be treated.

Should the treatment according to the invention not make it possible to obtain sufficient reduction of impurities, guard reactors for eliminating chlorine, metals and silicon can be added. Silicon can also be trapped on the top bed of a reactor of the HDT2 section or separately, upstream.

Chlorine and mercury can be separated by guard reactors in liquid or gaseous phase.

As the hydrotreatment reactions in the HDT1 and HDT2 sections are exothermic, quenching by cold hydrogen or dilution with an inert feedstock can be used to moderate the increase in temperature and to control the reaction. Dilution by an inert feedstock being able to be implemented by recycling the liquid fraction emerging from the reactors.

There may be intermediate quenchings between the beds or between the HDT1 and HDT2 reactors or no quenching. In the latter case, recycling of part of the flow leaving the HDT1 or HDT2 must be implemented to control the temperature. A strict control of the temperature in HDT1 must be conducted in order to avoid blocking of the reactor and degradation of the catalytic hydrogenation conditions.

The operating pressure in each of the HDT1 and HDT2 hydrotreatments is 5-140 bar, preferably 20-45 bar, for HDT1, and 20-140 bar, preferably 30-100 bar, for HDT2, typically 30-45 bar for HDT2.

Typical temperature range at the input of HDT1 at the start of the cycle (SOR: start of run): 150-250° C. The catalyst for HDT1 normally comprises Pd (0.1-10% weight) and/or Ni (0.1-60% weight) and/or NiMo (0.1-60% weight).

Typical temperature range at the input of HDT2 at the start of the cycle (SOR: start of run): 200-340° C.. Typical temperature range at the output of HDT2 (SOR): 300-380° C., up to 450° C. The catalyst for HDT2 normally comprises a NiMo (any type of commercial catalyst for refining or petrochemical application), potentially a CoMo in the very last beds at the reactor bottom (any type of commercial catalyst for refining or petrochemical application).

The top bed of the HDT2 should preferably be operated with a NiMo having a hydrogenating capability as well as a capability of trapping silicon. A top bed of this type can be considered to be a metal trap also having an HDN activity and a hydrogenating capability. It is possible to have two separate beds in an HDT2 reactor, with a quenching between the two beds or between the two reactors, if the two beds are in two distinct reactors, or no quenching at all. Ideally, the intermediate quenching is implemented by means of cold effluent from HDT2 or by an addition of cold hydrogen, i.e. at a temperature generally ranging from 15 to 30° C., in order to control the exotherm of HDT2. Depending on any metals present in the solid to be hydrotreated, a hydrodemetallization catalyst, for example commercial, can be added to the top bed of the HDT2 section in order to protect the lower catalytic beds from deactivation.

The hydrotreated effluent leaving the HDT2 section, optionally after washing with water to eliminate the inorganic compounds (hydrosulfide, hydrogen chloride, ammonia), can be used as it stands or fractionated according to the distillation temperature ranges, to supply a steam cracker, an FCC, a hydrocracker, a catalytic reformer or a pool of fuels or combustibles such as LPG, gasoline, jet fuel, diesel, fuel oil, or a pool of base oil.

In one embodiment, the hydrotreated liquefaction oil is sent to a hydrocracker. This hydrocracking comprises for example putting the hydrotreated effluent in contact with a hydrotreatment catalyst, in the presence of H2, to produce an effluent complying with the specifications of a steam cracker in terms of final boiling point (<370° C.).

Claims

1. Method for purifying 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) putting said composition in contact with an aqueous medium with a pH above 7, the putting in contact being implemented in turbulent regime having a Reynolds number higher than 2000 and at a temperature of less than or equal to 250° C. to obtain an effluent containing the modified composition,
c) subjecting the effluent from step (b) to (c1) a washing in the presence of water with a neutral or acid pH or of a solvent that is not miscible with the modified composition, or to the succession of a separation step (c2) and a step (c1), and obtaining a purified composition having a reduced heteroatom content, and a phase containing the basic compound and heteroatoms initially contained in the modified composition.

2. Method according to claim 1, characterized in that step (b) is implemented by circulating said composition and the aqueous medium inside at least one tube equipped with at least one internal element able to generate a turbulent regime.

3. Method according to claim 1, characterized in that, prior to step b) or during step (b), a basic compound is added to an aqueous medium in a sufficient quantity for the aqueous medium to have a pH above 7.

4. Method according to claim 3, 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 of an alkaline-earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or in a mixture.

5. Method according to claim 3, wherein step b) is characterized in that the basic compound is selected from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2, NH4OH, EtONa, MeONa, TEAOH, TBuOH, TMAOH, and mixtures thereof.

6. Method according to claim 1, characterized in that step (c) comprises at least one separation step (c2) for separating the phase containing the basic compound and heteroatoms, and the purified composition, and the phase containing the basic compound and heteroatoms is sent wholly or partly to step (b).

7. Method according to claim 1, characterized in that step (c) is preceded 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.

8. Method according to claim 1, characterized in that step c2) is implemented by (i) centrifugation, (ii) decantation, (iii) hydrocyclone, or (iv) a combination of two or three of these steps.

9. Method according to claim 1, wherein, prior to the treatment of step (b), said composition is subjected to (i) a filtration, (ii) washing with water or a polar solvent that is not miscible with the composition, (iii) a distillation, (iv) a decantation, or (v) to the combination of two, three or four of steps (i) to (iv).

10. Method according to claim 1, wherein:

(d) the purified composition of step (c) undergoes a catalytic hydrotreatment in one or two steps to provide a hydrotreated purified composition.

11. Method according to claim 10, characterized in that the hydrotreatment of step (d):

is implemented in a single step in which the purified composition of step (c) is hydrotreated at a temperature of 200 to 450° C., preferably from 200 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a hydrotreatment catalyst, or
is implemented in a first step (d-1) wherein the purified composition of step (c) is hydrotreated at a temperature of 80 to 250° C., preferably from 130 to 250° C. in the presence of hydrogen at an absolute pressure of 5 to 60 bar, preferably from 20 to 45 bar and in the presence of a first hydrotreatment catalyst, and in a second step (d-2) wherein the effluent resulting from step (d-1) is hydrotreated at a temperature of 200 to 450° C., preferably from 250 to 340° C. in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably from 30 to 100 bar and in the presence of a second hydrotreatment catalyst.

12. Method according to claim 10, wherein the purified and hydrotreated composition emerging from step (d) is furthermore washed with water to eliminate the inorganic compounds such as hydrosulfide, hydrogen chloride, or ammonia.

13. Method according to claim 1, wherein the purified composition of step (c) or the hydrotreated purified composition of step (d) is (f) used as it stands or separated into usable flows for preparing fuels and combustibles such as LPG, gasoline, diesel, heavy fuel oil or kerosene, and/or for preparing lubricants and/or base oils,

and/or treated, pure or diluted, optionally separated into usable flows, in:
g) a steam cracker for producing olefins, and/or
(h) a fluidized-bed catalytic cracker, and/or
(i) a hydrocracker, then optionally in a steam cracker, and/or
(i) a hydrotreatment reactor, in particular a catalytic hydrogenation reactor.

14. Equipment comprising an optional pre-treatment section (A), a section (B) for treating in turbulent regime, an optional section (C) for separating solids, a separation section (D), an optional hydrotreatment section (E) and/or an optional section for treatment in a steam cracker (F) and/or an optional section for treatment in a hydrocracker (G) and/or an optional section for treatment in a fluidized-bed catalytic cracker (H) and/or an optional section for treatment in a hydrotreatment reactor (I) and/or an optional section for preparing a fuel, a lubricant or a base oil (J), wherein the various sections are fluidically connected to implement the method according to claim 1.

Patent History
Publication number: 20260258307
Type: Application
Filed: Jul 26, 2023
Publication Date: Sep 3, 2026
Applicant: TotalEnergies OneTech (Courbevoie)
Inventors: Thomas COUSTHAM (Ablon), Hélène COULOMBEAU-LEROY (Montivillers), Cindy ADAM (Wierde), Katell LE LANNIC (Uccle), Walter VERMEIREN (Houthalen), Guillaume HAUCHECORNE (Bretteville du Grand Caux)
Application Number: 18/879,920
Classifications
International Classification: C10G 53/12 (20060101); C10G 19/02 (20060101); C10G 31/08 (20060101); C10G 31/09 (20060101); C10G 31/10 (20060101); C10G 53/04 (20060101); C10G 67/04 (20060101); C10G 67/10 (20060101); C10G 67/14 (20060101);