FR3138441A1 - Method for purifying a plastic liquefaction oil composition by cavitation and use - Google Patents

Abstract

The invention relates to a process for purifying a composition comprising a plastic liquefaction oil comprising a step of treating the composition by hydrodynamic cavitation in the presence of a basic compound at a temperature of at most 350°C to obtain a effluent containing the modified composition. This effluent is then subjected to (c1) washing with water or a solvent immiscible with the purified composition, (c2) separation, or to the succession of steps (c2) and (c1), to obtain the composition purified having a reduced heteroatom content and a phase containing the basic compound. Abstract figure: fig.1

Description

Method for purifying a plastic liquefaction oil composition by cavitation and use Technical field of the invention

The present invention relates to a process for purifying by cavitation a composition comprising a plastic liquefaction oil and its subsequent use in refining and petrochemical processes. The process according to the invention makes it possible in particular to reduce the concentration of heteroatoms in the fillers coming from plastic waste, in particular with a view to their use in a steam cracking process.

Technology background

Plastic waste is most often directed to landfills or incinerated, and a smaller portion is directed to recycling. However, there is a significant need, encouraged by regulations, to limit plastic waste in landfills. On the other hand, the disposal of plastic waste in landfills is becoming increasingly difficult. It is therefore necessary to recycle plastic waste.

A possible route to recycling plastic is the liquefaction of plastic by pyrolysis or hydrothermal liquefaction. However, the resulting plastic oil generally contains large quantities of dienes and heteroatoms, including metals. These numerous heteroatoms, including metals, are contaminants for the catalysts of the hydrotreatment processes usually used to recycle plastics. Additionally, dienes react easily to form gums. Dienes are also precursors to coke in a steam cracker. It is therefore necessary to treat plastic liquefaction oils to be able to recycle them.

There are many treatment methods to reduce the heteroatom content of plastic liquefaction oils.

Patent JP3776335 discloses a process for dechlorination and denitrogenation of an oil resulting from the catalytic or thermal cracking of plastic waste which is treated at different temperatures up to 425°C for 30 minutes in the presence of an aqueous solution of a compound alkaline of an alkali or alkaline earth metal at a pH greater than or equal to 7. The reaction product is then separated from the aqueous alkaline solution by liquid-liquid separation with ethyl ether.

Patent application WO2012/069467 claims a process for eliminating siloxanes contained in a plastic pyrolysis oil by heat treatment between 200 and 350°C in the presence of an alkali metal hydroxide in the solid state or in solution. The use of calcium hydroxide at 5% by weight at 225°C does not make it possible to obtain a reduction in the siloxane content (table 5, p.12 and lines 9 to 11, p.13). At the end of the reaction, the pyrolysis oil is separated by distillation under reduced pressure.

Patent FI128848 describes a process sequence comprising heat treatment of a plastic pyrolysis oil at at least 200°C in the presence of an alkaline aqueous solution. At the end of the reaction, the pyrolysis oil is separated from the alkaline aqueous phase. A final hydrotreatment makes it possible to obtain a steam cracker charge which is optionally washed with an acid solution before introduction into the steam cracker.

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

Patent application WO2021/105326 claims a process for recovering liquefied plastic waste comprising a step of pre-treating the liquefied plastic waste by bringing it into contact with an aqueous medium having a pH of at least 7 at a temperature of 200°C or more , followed by liquid-liquid separation in which the aqueous phase is separated from the organic phase, to produce pretreated liquefied waste plastic. The proposed solution includes the use of a solution of NaOH in water. The separation of the aqueous and organic phases is carried out by physical methods (centrifugation) or chemical methods (addition of separation aid additives, for example non-aqueous solvents, addition of additional quantity of the aqueous medium used for the in contact with or an aqueous medium having a different alkaline substance concentration), or by gravity.

Most existing purification treatments are carried out at relatively high temperatures. In addition, these treatments do not provide means for lowering the content of silicon or even alkali/alkaline earth metals present in the plastic pyrolysis oil after pretreatment with a base. However, it is known that the presence of alkali/alkaline earth metals can lead to the deactivation of catalysts used in catalytic processes for recycling purified plastic liquefaction oil.

There is therefore a need to improve existing purification processes.

The invention aims to propose a process for purifying plastic liquefaction oil making it possible to facilitate its purification, in particular by limiting the implementation temperature while maintaining high reduction performances in heteroatoms, in particular in silicon, including for the reduction of the content of alkali and/or alkaline earth metals resulting from the treatment of plastic liquefaction oil with a basic compound containing for example an alkali or alkaline earth metal.

To this end, the invention relates to a process for purifying a composition comprising a plastic liquefaction oil comprising the following steps:

(a) providing a composition comprising a plastic liquefaction oil, said composition containing at least 20 ppm heteroatoms,

(b) treating the composition supplied in step (a) by hydrodynamic cavitation in the presence of a basic compound at a temperature of not more than 350°C to obtain an effluent containing the modified composition,

(c) subjecting the effluent from step (b) to (c1) washing with water or a solvent immiscible with the modified composition, c2) separation, or to the succession of steps (c2) and (c1), and obtain 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 by hydrodynamic cavitation in the presence of a basic compound to allow the elimination of impurities containing heteroatoms, in particular alkali, alkaline earth metals, silicon, chlorine, bromine, iron, aluminum and others, likely to damage the catalyst of a subsequent hydrotreatment step.

Hydrodynamic cavitation treatment allows:

- to transfer the impurities present in the composition to be treated to an aqueous phase or an organic phase immiscible with the composition, the aqueous or organic phase concentrated in impurities can then be separated, and/or

- to promote reactions between the basic compound and compounds containing heteroatoms thanks to the energy provided by cavitation leading to better contact between the oil to be treated and the basic compound. The impurities can then be removed by washing with a solvent immiscible with the composition and/or by separation of a phase immiscible with the composition and containing the impurities.

Step (b) according to the invention may comprise one or more of the following characteristics:

• step (b) is carried out in the presence of 0.1 to 50% m of basic compound relative to the total mass of the treated composition,
• prior to step b) or during step b), (i) a solid basic compound is added to the composition of step a), (ii) a basic compound previously dissolved in an aqueous medium, preferably water, or (iii) a basic compound previously dissolved in a solvent,
• the basic compound comprises an oxide, hydroxide, bicarbonate or alkoxide of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or bicarbonate of a quaternary ammonium cation, alone or in mixture,
• the basic compound is chosen from LiOH, NaOH, CsOH, Ba(OH) ₂ , Na ₂ O, KOH, K ₂ O, CaO, Ca(OH) ₂ , MgO, Mg(OH) ₂ , NH ₄ OH, TMAOH, TEAOH, TBuOH, MeONa, EtONa and their mixtures,
• step b) is carried out at a temperature of 50 to 350°C, preferably 50 to 250°C, more preferably 90 to 200°C, more preferably 90 to 190°C,
• step b) of hydrodynamic cavitation is carried out for a duration of 0.1 second to 2 hours, preferably 1 minute to 1 hour, more preferably 1 minute to 20 minutes or 1 minute to 16 minutes.

Step (c) according to the invention may comprise one or more of the following characteristics:

• step (c) is preceded or followed by a solids separation step by (i) filtration, (ii) centrifugation, (iii) hydrocyclone or (iv) a combination of two or more of these steps,
• step c1) is carried out in the presence of water at neutral, basic or acidic pH, or in the presence of an organic solvent immiscible with the composition, preferably in the presence of water,
• step c2) is carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps,
• step (c) comprises at least the separation step (c2) for separating the phase containing the basic compound and heteroatoms, and the purified composition, and the phase containing the basic compound and heteroatoms is returned in whole or in part in step (b).

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

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

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

The hydrotreatment of step (d):

- can be carried out in a single step in which the purified composition of step (c) is hydrotreated at a temperature of 200 to 450°C, preferably 200 to 340°C in the presence of hydrogen at absolute pressure from 20 to 140 bars, preferably from 30 to 100 bars and in the presence of a hydrotreatment catalyst, or

- can be carried out in a first step (d-1) in which the purified composition of 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 5 to 60 bars, preferably 20 to 45 bars and in the presence of a first hydrotreatment catalyst, and in a second step (d-2) in which The effluent from step (d-1) is hydrotreated at a temperature of 200 to 450°C, preferably 250 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably of 30 to 100 bars and in the presence of a second hydrotreatment catalyst.

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

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

(f) used as such or separated into usable streams for the preparation of fuels such as LPG, gasoline, diesel, heavy fuel oil, kerosene and/or for the preparation of lubricants and/or base oils,

and/or treated, pure or diluted, optionally separated into usable streams, in:

(g) a steam cracker to produce olefins, and/or

(h) a fluidized bed catalytic cracker, and/or

(i) a hydrocracker, then optionally in a steam cracker, and/or

(j) a hydrotreatment reactor, in particular a catalytic hydrogenation reactor.

Preferably, the purified composition of step (c) or the purified hydrotreated composition of step (d) can be subjected, pure or diluted, optionally after separation into usable streams, to a steam cracking step (e) for produce olefins such as ethylene and propylene, which can then be used to make new polymers through polymerization.

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 an installation, in particular adapted to the implementation of the method according to the invention, comprising an optional pretreatment section (A), a cavitation treatment section (B), an optional separation section (C). solids, a separation section (D), an optional hydrotreatment section (E) and/or an optional treatment section in a steam cracker (F) and/or an optional treatment section in a hydrocracker (G) and/ or an optional treatment section in a fluidized bed catalytic cracker (H) and/or an optional treatment section in a hydrotreatment reactor (I) and/or an optional fuel preparation section or a lubricant or base oil (J), in which the different sections are fluidly connected to implement the method according to the invention.

Definitions

The Hourly Volume Velocity (HVR) is defined as the hourly volume of feed flow per unit of catalytic volume and is expressed here in h ^-1 .

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

The specification of a number domain without decimal places includes all whole numbers and, where appropriate, fractions thereof (for example, 1 to 5 may include 1, 2, 3, 4 and 5 when reference is made to a number of elements, and may also include 1.5, 2, 2.75 and 3.80, when reference is made to, for example, a measurement.).

Specifying a decimal place also includes the decimal place itself (for example, "from 1.0 to 5.0" includes 1.0 and 5.0). Any range of numerical values recited herein also includes any subrange 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 compared to 100g of a composition comprising it.

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

By “heteroatom”, we mean any elements of an organic compound other than carbon and hydrogen.

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

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

The term "naphtha" refers to the general definition used in the oil and gas industry. In particular, it is a hydrocarbon coming from the distillation of crude oil and whose boiling point is between 15 and 250°C, according to the ASTM D2887 standard. Naphtha contains almost no olefins because the hydrocarbons come from crude oil. A naphtha is generally considered to have a carbon number between C5 and C11, although the carbon number can in some cases be as high as C15. It is also generally accepted that the density of naphtha is between 0.65 and 0.77 g/mL.

By “liquefaction oil”, we mean an oil resulting from a pyrolysis process and/or a hydrothermal liquefaction process of a hydrocarbon feedstock. This hydrocarbon filler may include plastics, biomass and/or elastomers, alone or in a mixture, particularly in the form of waste. A liquefaction oil can be formed from a mixture of two or more liquefaction oils originating from the liquefaction of different hydrocarbon feedstocks.

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

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

The term “plastic liquefaction oil” or “oil resulting from the liquefaction of plastic” or “waste plastic liquefaction oil” or “liquefaction oil resulting from the liquefaction of waste containing plastics” refers to hydrocarbon liquid products obtained following pyrolysis or hydrothermal liquefaction of thermoplastic and/or thermosetting polymers, alone or in mixture, and generally in the form of waste, optionally in mixture with at least one other filler, in particular in the form of waste, such as biomass, for example chosen from lignocellulosic biomass, paper and cardboard, and/or an elastomer, for example optionally vulcanized latex or tires.

Plastic can be of any type, including any type of new or used plastic, included in household (post-consumer) or industrial waste. By plastics we mean materials made up of polymers and optionally auxiliary components such as plasticizers, fillers, dyes, catalysts, flame retardants, stabilizers, etc. For example, these polymers can be polyethylene, halogenated polyethylene (Cl, F ), polypropylene, polystyrene, polybutadiene, polyisoprene, poly(ethylene terephthalate) (PET), acrylonitrile-butadiene-styrene (ABS), polybutylene, poly(butylene terephthalate) ( PBT), polyvinyl chloride (PVC), polyvinylidene chloride, polyester, polyamide, polycarbonate, polyether, epoxy polymer, polyacetal, polyimide, polyesteramide, silicone etc. In general, any polymer or mixture of polymers capable of producing hydrocarbons by liquefaction can be used.

Biomass can be defined as an organic plant or animal product. Biomass thus includes (i) biomass produced by surplus agricultural land, not used for human or animal food: dedicated crops, called energy crops; (ii) biomass produced by deforestation (forest maintenance) or cleaning of agricultural land; (iii) agricultural residues from cereal crops, vines, orchards, olive trees, fruits and vegetables, agri-food residues, etc.; (iv) forest residues from silviculture and wood processing; (v) agricultural residues from livestock (manure, slurry, litter, droppings, etc.); (vi) organic household waste (paper, cardboard, green waste, etc.); (vii) ordinary industrial organic waste (paper, cardboard, wood, putrescible waste, 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 a range defined by any two of these limits, one or more of the aforementioned biomasses, residues and organic waste, and the remainder consisting of plastic waste, optionally mixed with elastomers, in particular in the form of waste.

Elastomers are linear or branched polymers transformed by vulcanization into an infusible and insoluble, weakly crosslinked 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 agent, 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, copolymers of isobutylene isoprene, chlorinated or brominated, butadiene acrylonitrile 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 a range defined by any two of these limits, of one or more aforementioned elastomers, in particular in the form of waste, the remainder consisting of plastic waste, optionally mixed with biomass, residues and organic waste.

Cavitation is the phenomenon of vapor or gas bubbles forming in a flowing liquid in regions where the pressure of the liquid is lower than its vapor pressure at the temperature in question. It is a phenomenon of nucleation, growth and implosion (collapse) of cavities filled with vapor or gas, which can be obtained by the passage of ultrasound (acoustic cavitation), by a laser, by the injection of steam into a cold fluid or by changes in flow and pressure (hydrodynamic cavitation). In the case of hydrodynamic cavitation, the geometry of the flow is modified such that the kinetic energy is increased by a constriction of the flow which results in a considerable reduction in the local pressure of the liquid and a corresponding increase in the 'kinetic energy. When the liquid pressure falls below the vapor pressure of that same liquid, millions of vapor cavities are created, which are subject to turbulent conditions of varying pressure fields downstream of the constriction. The lifespan of these cavities is very short (a few microseconds). The cavities eventually collapse by implosion, which generates very high pressures (up to 100 MPa) and temperatures (10,000 K), as well as intense shear forces. The energy released during the implosion and/or pulsation of cavitation bubbles thus modifies the properties of the fluids and intensifies transport phenomena and certain chemical transformations.

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

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

The term “Bromine Index” is the number of milligrams of bromine that react with 100 g of sample and can be measured according to the ASTM D2710 or ASTM D5776 methods.

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

The concentration of metals in hydrocarbon matrices can be determined by any known method. Acceptable methods include X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Specialists in analytical sciences know how to identify the most suitable method for measuring each metal and generally each heteroelement depending on the hydrocarbon matrix considered. The oxygen content can be measured according to the standard: ASTM D5622-17 / D2504-88 (2015). The nitrogen content can be measured according to the standard: ASTM D4629-17. The sulfur content can be measured according to the ISO 20846:2011 standard. The halogen content, in particular chlorine, bromine, fluorine, can be measured according to the standard: ASTM D7359-18.

By “hydrotreatment” we mean any process 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 chosen from hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrodemetallation (HCM), hydrocracking, hydroisomerization and hydrogenation (hydrogenation of unsaturated compounds into saturated compounds).

By “hydrotreatment catalyst”, we mean a catalyst promoting the incorporation of hydrogen into products. This type of catalyst is typically a metal catalyst comprising one or more metals from groups 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 of the periodic table.

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

Detailed description of the invention

Description of the composition comprising a plastic liquefaction oil

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

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

Alternatively, the composition may include at least 1% m plastic liquefaction oil. The remainder can then be composed of at most 99% by mass of a diluent or solvent such as a hydrocarbon and/or one or more of the components listed below, preferably a component coming from biomass, biomass waste or elastomeric waste.

In one embodiment, the composition may 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 of plastic liquefaction oil. The composition may comprise at most 80%m or 90%m or 95%m or 100%m of plastic liquefaction oil. The mass content of plastic liquefaction oil(s) of the composition can be included in any interval defined by two of the limits previously set.

The composition may further comprise a component originating from biomass, biomass waste or elastomeric waste, such as tall oil, used food oil, animal fat, vegetable oil such as rapeseed oil, canola, castor, palm, soya, an oil extracted from an algae, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, a biomass liquefaction oil, in particular a biomass liquefaction oil such as Panicum virgatum or a lignocellulosic biomass liquefaction oil, for example a wood, paper and/or cardboard liquefaction oil, an oil obtained by liquefaction of crushed used furniture, an elastomer liquefaction oil for example possibly vulcanized latex or tires, as well as their mixtures.

The composition may further include a component that is a diluent miscible with the plastic liquefaction oil. This diluent preferably has a diene number of not more than 0.5 g I2/100 g, measured according to UOP 326-17, a bromine number of not more than 5 g Br2/100 g, measured according to ASTM D1159. The diluent is preferably chosen from a naphtha and/or a paraffinic solvent and/or a diesel or a direct distillation gas oil, containing at most 1% by weight of sulfur, preferably at most 0.1% by weight of sulfur, and/or a hydrocarbon stream having a boiling range between 50°C and 150°C or a boiling range between 150°C and 250°C or a boiling range between 200°C and 350°C , preferably having a bromine number of not more than 5 gBr2/100g, and/or a diene number of not more than 0.5 gI2/100g or any combination thereof.

The composition may have a bromine number of at most 150 g Br2/100g, preferably at most 100 g Br2/100g, even more preferably at most 80 g Br2/100g, the most preferred being at plus 50 g Br2/ 100g, as measured according to ASTM D1159.

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

Step (a) of providing the composition may include:

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

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

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

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

The waste treated in step (a1) can be plastic waste possibly mixed with biomass, as previously described.

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

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

The composition of the plastic liquefaction oil depends on the nature of the liquefied plastic, and optionally on any other waste liquefied with the plastic, and is essentially (in particular more than 80% m/m, most often more than 90%m/m) consisting of hydrocarbons having 1 to 150 carbon atoms and impurities.

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

In particular, a plastic liquefaction oil may include a Bromine number of 10 to 130 g Br/100g, as measured according to standard ASTM D1159, and/or a maleic anhydride number (UOP326-82) of 1 to 55 mg. of maleic anhydride/1g.

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

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

A plastic liquefaction oil may in particular comprise one or more of the following heteroatom contents: from 0 to 8% m/m of oxygen (measured according to the ASTM D5622 standard), from 1 to 13,000 ppm of nitrogen (measured according to the standard ASTM D4629), 2 to 10,000ppm of sulfur (measured according to standard ISO 20846), 1 to 10,000ppm of metals (measured by ICP), 50 to 6,000ppm of chlorine (measured according to standard ASTM D7359-18), 0 to 200ppm bromine (measured according to ASTM D7359-18), 1 to 40ppm fluorine (measured according to ASTM D7359-18), 1 to 2000 ppm silicon (measured by XRF).

Detailed description of the optional step pre-treatment of the composition

Between step (a) and (b), the invention may also comprise an optional pretreatment step, in which said composition is subjected, in particular immediately before step (b) or (c2), to (i) a filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of the steps ( i) to (iv). This additional step can make it possible to remove 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 help avoid the formation of solids and/or gels during step (c1).

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

When water is used for washing (ii), it can have 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 (C ₆ H ₈ O ₇ ), formic acid (CH₂O₂), acetic acid (CH₃COOH). Examples of inorganic acids are sulfamic acid (H ₃ NSO ₃ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ). A basic pH can be obtained by the addition of alkali and alkaline earth metal oxides, alkali and alkaline earth metal hydroxides (e.g. NaOH, KOH, Ca(OH) ₂ ), alkali and alkaline metal bicarbonates -earth and amines (e.g. triethylamine, ethylenediamine, ammonia).

The polar solvent may have a density greater 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% higher or lower than that of the composition.

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

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

In particular, this recovery rate can be determined by following the following procedure:

• Introduction of 50 mL of composition containing a liquefaction 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 +/-0.1 mL,
• Insert a magnetic bar, close the balloon with a polypropylene cap,
• Stir the mixture on a mechanical stirring plate at a speed of 500 rpm for 5 min,
• At the end of 5 minutes, stop 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 a volume less than or equal to 2mL and an accuracy of +/-0.1 mL for a volume greater than 2mL. Wait for complete demixing by decantation and measure the volume of the 2 phases using the graduations. We consider that complete demixing is reached when the volumes of the two phases no longer vary.

Acceptable immiscible polar solvents include (i) sulfur compounds, for example dimethyl sulfoxide, (ii) nitrogen compounds, for example N,N -dimethylformamide, (iii) halogenated compounds, for example dichloromethane or chloroform, (iv) ethylene glycol, or:

• glycol ethers, including in particular polyethylene glycol of chemical formula HO-(CH ₂ -CH ₂ -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(CH ₃ )CH ₂ ] _n OH with a mass average molar mass of 130 to 800g/mol, for example dipropylene glycol and tetrapropylene glycol,
• dialkyl formamides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethyl formamide (DMF),
• dialkyl sulfoxides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethyl sulfoxide (DMSO) and sulfolane
• compounds comprising a furan ring,
• cyclic carbonate esters, comprising in particular from 3 to 8 or from 3 to 4 carbon atoms, in particular propylene carbonate and ethylene carbonate.

One or more of the aforementioned solvents may be used. However, advantageously, only one of the aforementioned solvents can be used provided that it is immiscible 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 -CH ₂ -O) _n -H with a mass average molar mass of 90 to 800g /mol or polypropylene glycol of chemical formula H[OCH(CH ₃ )CH ₂ ] _n OH with a mass average molar mass of 130 to 800g/mol, or a compound comprising a furan ring, or a cyclic carbonate ester, in particularly propylene or ethylene carbonate, alone or in a mixture, preferably alone.

In a preferred embodiment, the polar solvent is chosen from propylene carbonate, ethylene carbonate, ethylene glycol and polyethylene glycol of chemical formula HO-(CH ₂ -CH ₂ -O) _n -H of mass average molar mass of 90 to 800g/mol, alone or in a mixture, preferably alone.

Description of the basic compound used in step (b)

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

Advantageously, the quantity of basic compound used is 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 relative to the total mass of the treated composition (composition provided by step (a)). For example, the quantity of basic compound used can be from 0.1 to 15% by mass, more preferably from 1 to 15% by mass, more preferably from 1 to 10% by mass, in particular from 1 to 5%. by mass, relative to the total mass of the treated composition (composition provided by step (a)).

The basic compound can be added to the composition provided in 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 hydrodynamic cavitation.

The basic compound can be added to the composition in solid form or dissolved in an aqueous medium, preferably water, or in a solvent, miscible or immiscible with said composition.

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

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

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

In a preferred embodiment, the basic compound can be chosen from LiOH, NaOH, CsOH, Ba(OH) ₂ , Na ₂ O, KOH, K ₂ O, CaO, Ca(OH) ₂ , MgO, Mg(OH) ₂ , EtONa, MeONa, NH ₄ OH, TEAOH, TBuOH, TMAOH, and their mixtures. A preferred basic compound may be chosen from NaOH, KOH and mixtures thereof, preferably in solution in water.

The solvent used to solubilize the basic compound can be water, an alcohol, for example methanol or ethanol, or any other organic solvent making it possible to solubilize the chosen basic compound, preferably water.

When the basic compound is dissolved in a solvent, those skilled in the art will then choose a sufficient quantity of solvent to dissolve/solubilize it, preferably the lowest possible quantity of solvent.

Advantageously, the basic compound added in step (b) is in solution in water or in a solvent, and the basic compound content of the water or the solvent is 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 water or the solvent is saturated with basic compound.

The volume ratio of the solvent containing the basic compound/composition, i.e. the volume ratio of the mixture (basic compound + solvent)/composition, could be from 0.1/99.9 to 80/20, from 1/99 to 80 /20, from 1/99 to 70/30, from 1/99 to 65/35, from 1/99 to 60/40, from 1/99 to 50/50, or in any interval defined by any two of the terminals aforementioned. A solution, in particular an aqueous solution, saturated with basic compound may be used.

Detailed description of the step b) of treatment by hydrodynamic cavitation

In step (b), the composition is treated under conditions effective to generate cavitation characteristics, in other words the formation and collapse of cavitation bubbles, which enhance the modification and subsequent transfer of contained impurities. in the composition towards an aqueous phase or an organic phase immiscible with the composition. In particular, step (b) is implemented under conditions which do not cause conversion of the composition to be treated.

Hydrodynamic cavitation occurs in all hydraulic systems in which considerable pressure differences occur, such as turbines, pumps and high-pressure nozzles.

The effective conditions for generating cavitation characteristics depend on the properties of the fluid flow, the design of the cavitation device, the flow velocity, e.g. obtained by a pump, the temperature of the fluid flow and can be easily determined by those skilled in the art. The cavitation phenomenon is characterized by the dimensionless cavitation number Cv, which is defined as follows:

C _v =(PP _v )/0.5ρV ^2,

Or :

P [Pa] is the static pressure downstream of a restriction orifice,

Pv [Pa] is the vapor pressure of the fluid,

V [m/s] is the average fluid velocity through the orifice, and

ρ [kg/m3] is the density of the fluid.

The cavitation index at which cavitation begins is the cavitation onset index, C _vi . Cavitation ideally begins at C _vi =1, and a Cv<1 indicates a higher degree of cavitation. Cavitation can start at a higher C _vi when gases are dissolved in the liquid, characterized by its P _v . The amount of cavitation events per unit flow rate is another parameter that can be taken into account. The effect of surface tension and cavity size on hydrostatic pressure is defined as follows: P _i =P ₀ +2a/R, where P _i is the hydrostatic pressure, a is the surface tension and R is the radius of the bubble. The smaller the bubble, the more energy released during its implosion.

Step (b) can be carried out at a temperature of at most 350°C. In a preferred embodiment, step (b) can be carried out at a temperature of 50 to 350°C, preferably 50 to 250°C, more preferably 90 to 200°C, even more preferably from 90 to 190°C or in any interval defined by any two of these limits. In particular, hydrodynamic cavitation conditions can make it possible to eliminate impurities at a temperature lower than the temperature of a treatment in the presence of a basic compound but without hydrodynamic cavitation. Advantageously, during step (b), the composition provided in step (a) can be preheated, preferably in the presence of the basic compound (previously added in solid or solubilized form), to the implementation temperature of step (b) before being subjected to hydrodynamic cavitation conditions.

The cavitation treatment is typically maintained for a sufficient time to obtain a modified composition subsequently allowing the recovery of a purified composition having a reduced heteroatom content.

Hydrodynamic cavitation step b) can in particular be carried out for a duration of 0.1 second to 2 hours, preferably 1 minute to 1 hour, more preferably 1 minute to 20 minutes or 1 minute to 16 minutes .

The hydrodynamic cavitation treatment of step (b) can be carried out in one, two or more hydrodynamic cavitation treatment steps, for example by passing the composition to be treated through one or more hydraulic systems or cavitation devices, for example placed in series and/or in parallel, capable of generating hydrodynamic cavitation.

It may also be possible to provide at least one hydrodynamic cavitation treatment step in the presence of a solid basic compound or solubilized in a solvent miscible or immiscible with the composition and at least one hydrodynamic cavitation treatment step in the presence of a basic compound. dissolved in water.

Step (b) of hydrodynamic cavitation can therefore include:

• pumping the composition to be treated through at least one cavitation device,
• generating cavitation features to modify impurities.

Suitable cavitation devices which can be used are for example disclosed in documents WO201098783A1, US8911808B2, US7762715B2, US8042989B2.

For example, a suitable cavitation device includes a flow path through which fluid is pumped, such as that described in US8911808B2, in which a predetermined pumping pressure is applied, preferably in the range 50 to 50,000psi.

A suitable hydrodynamic cavitation device may have a constriction (constriction) section formed by a plate having a single orifice. A throttle section may also be formed with a plate having several orifices, for example two or three holes, a venturi tube, a rotor-stator system, or a liquid whistle. Instead of a constriction section, a vortex diode having a tangential inlet port and an axial outlet port can also be used to generate the cavitation bubbles.

For example, in the case of an orifice plate with at least one hole, the flow passes through a constriction where local velocities suddenly increase due to the reduction in flow area, resulting in lower pressures which may even decrease to below the vapor pressure of the liquid medium. Choosing a correct flow arrangement in the hydrodynamic cavitation device is of paramount importance to maximize the effects of cavitation in the desired cost-effective manner.

The choke can be a venturi, a single hole, or multiple holes in an orifice plate, as described in a study titled "Beer-brewing powered by managed hydrodynamic cavitation: Theory and real-scale experiments" by Albanese L. et al. (J. of Cleaner Production, 2017, 142, 1457-1470). The use of multiple orifice plates allows different cavitation intensities to be obtained. Additionally, the number of cavitation events generated in the reactor varies. Thus, the orifice plate configuration provides great flexibility in terms of operation (control of inlet pressure, inlet flow, temperature) and geometric conditions (different arrangements of holes on orifice plates , such as circular, triangular, etc., as well as the geometry of the hole itself, which modifies the shear of the resulting fluid, leading to different cavitation intensities). The orifice plate configuration provides maximum flexibility and can also be used at relatively larger operating scales. It should also be noted that scaling of such devices is relatively easier, as pump efficiency increases with increasing size (flow rate and discharge rate), which will necessarily result in higher energy yields.

Hydrodynamic cavitation can also be generated in rotating equipment, such as a rotor-stator system. When the tip speed of the rotating device (turbine) reaches a critical speed, the local pressure near the periphery of the turbine drops and approaches the vapor pressure of the liquid. This results in the generation of cavitation bubbles. Subsequently, as the liquid moves away from the impeller toward the reservoir boundary, the liquid pressure is restored at the expense of the speed head. This causes the cavitation bubbles that have traveled with the liquid mass to collapse. Energy consumption in these types of reactors is higher and flexibility on design parameters is less compared to reactors based on the use of multiple orifice plates. An example of rotating equipment is Rotocav® from the company Cavimax in the United Kingdom.

Another example of a suitable hydrodynamic cavitation device is a liquid whistle which is a kind of static mixer that passes a high pressure fluid through an orifice and then onto a blade. Such a high pressure homogenizer is a high pressure positive displacement pump with throttle which operates according to the principle of high pressure decompression. Typically, a high pressure homogenizer reactor consists of a feed tank and two throttle valves, designated as the first stage and second stage, to control the operating pressure in the hydrodynamic cavitation reactor. Sonic Corporation in the United States is an example of a technology provider for a high-pressure homogenizer used to create hydrodynamic cavitation. Their Sonolator® high pressure homogenizers use a high pressure positive displacement pump connected to the homogenizer forces liquid through a specially designed orifice at pressures up to 42 MPa. The fluid changes speed dramatically over a very short distance and accelerates to over 90 m/s, creating high shear and turbulence in the treated composition. Immediately afterwards, the solution impacts a blade placed in its path. Extreme hydrodynamic cavitation occurs when the solution flows over the blade where aggressive and turbulent countercurrents form.

Another suitable hydrodynamic cavitation technology is a vortex-type hydrodynamic cavitation generator, VoDca® from the company Water Knight in the Netherlands. This device includes a tangential inlet and a cylindrical axial outlet connected by a disc-shaped chamber, imparts and maintains the angular momentum of the fluid throughout the process. It creates a sufficient pressure drop to produce cavities/microbubbles which collapse in a controlled manner downstream of the system. The equipment achieves high cavitation efficiency and the vortex protects the cavity walls from collapsing and causing no erosion. Cavitation Technologies, Inc. (CTi) is another company providing such a solution for hydrodynamic cavitation.

Step (b) (comprising for example the steps of pumping and generating cavitation) can be repeated one or more times before carrying out step (c), either by returning the composition leaving the cavitation device to the the entrance thereof, or by use of several cavitation devices in series.

Alternatively, step (b) (comprising for example the pumping and cavitation generation steps) and step (c) can be repeated one or more times, for example by returning the purified composition of step ( c) at the input of step (b) or by use of several units in series capable of implementing steps (b) and (c) successively.

Cavitation temporarily separates the constituents of the high-boiling composition from trapped gases, water vapor, and volatile impurity vapors that may be found in the bubbles. The pulsation and/or implosion of these bubbles mix the oil and the basic compound, which considerably increases the contact surface of these components and promotes the transfer of impurities to an aqueous phase or an organic phase immiscible with the composition. or promotes the modification of impurities.

The composition to be treated may also be mixed with a solvent such as hexane to improve flow or small amounts of soluble gases may be added to improve cavitation onset. Suitable gases are dihydrogen, dinitrogen, carbon dioxide, steam or mixtures thereof.

The composition to be treated can also be mixed with a light hydrocarbon fraction or with a gas stream to improve cavitation. The addition of such a light hydrocarbon fraction or gas stream can further reduce the viscosity of the treated feed during hydrodynamic cavitation processing and therefore reduce the pressure loss in the device, which can lower the vapor pressure, improve the creation of bubbles and therefore cavitation.

In one embodiment, a light fraction comprising C4-C15 hydrocarbons, preferably C5-C10 hydrocarbons, can be added to the composition treated during step (b), for example before this step. This light fraction mainly comprises, for example more than 90% by weight or more than 95% by weight, C4-C15 or C5-C10 hydrocarbons. Such a light fraction is for example a naphtha fraction, in particular a C5-C10 naphtha fraction, for example chosen from a naphtha fraction of mineral origin resulting from the treatment of mineral oils, a naphtha fraction recovered by fractionation of the fractionated composition of the invention, or their mixture.

In one embodiment, the gas stream can be added to the composition treated during step (b), for example before this step. The gas stream may include or consist of dihydrogen, carbon dioxide, dihydrogen sulfide, methane, ethane, propane or mixtures thereof.

Advantageously, the light fraction or the gas flow can represent from 0.1 to 10% by weight of the composition treated in step (b).

Because hydrodynamic cavitation processing ensures vigorous mixing, it may require lower base quantities than conventional non-cavitation methods. Additionally, hydrodynamic cavitation processing can be easily scaled to accommodate large flow rates.

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

Detailed description of the optional additional solids separation step

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 solids separation step is particularly advantageous before step (c2) because it can facilitate phase separation by eliminating all or part of the solids present in the effluent from step (b).

Detailed description of step (c)

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

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

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

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

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

(A3) the separation step (c2) can be followed by a washing step (c1) of the liquid phase containing the purified composition recovered at the outlet of step (c2),

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

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

(C1) the washing step (c1) which makes it possible to recover a phase containing the purified composition and a phase containing the basic compound, the impurities, the water or the solvent used for washing and the aqueous medium or the solvent not miscible used to add the basic compound, or

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

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

In cases (A2), (A3), (C2) and (C3), we can advantageously recover the phase containing the basic compound recovered at the outlet of the separation step (c2) and return it in whole or in part to step (b) of treatment by hydrodynamic cavitation. This makes it possible to reduce the quantities of basic compound to be used and thus reduce the associated costs.

Detailed description of the washing step (c1)

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

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

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

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

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

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

An acidic pH can be obtained by adding one or more organic or inorganic acids. Examples are cited with reference to 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 washing (ii) or those used in step b). Preferably, the water can have a pH of 7.1 to 14.

The immiscible solvent may be any organic solvent immiscible with the composition, in particular in which the impurities containing heteroatoms are soluble. An immiscible solvent that can be used is for example a polar solvent, in particular those described in the optional pre-treatment step.

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

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

During step (c1), the solvent or water/effluent volume ratio containing the modified or 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 aforementioned limits.

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

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

The washing step (c1) can be carried out continuously or in batches.

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 can be a liquid/liquid separation or a solid/liquid separation. It can advantageously be carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps.

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, in particular when the latter has been added in solid form or in a solvent immiscible with the composition (water or immiscible organic solvent). This step (c2) then separates a phase containing the purified composition and a phase containing the basic compound and the impurities, and, where appropriate, the water or the solvent immiscible with the composition. This phase containing the basic compound can then be returned to step (b) to reuse the basic compound. This makes it possible to reduce the amount of total basic compound consumed in step (b).

Step (c2) can also be carried out on the effluent containing the purified composition obtained at the outlet of step (c1), which makes it possible to eliminate any solids formed during the washing step (c1). ).

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

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

Detailed description of the step optional hydrotreating is lying catalytic (d)

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

Alternatively, the hydrotreatment of step (d) can be carried out in a first step (d-1) in which the effluent 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 5 to 60 bars, preferably 20 to 45 bars, and in the presence of a first hydrotreatment catalyst, preferably a hydrogenation catalyst, for example a hydrogenation catalyst comprising Pd (0.1-10% by weight) and/or Ni (0.1-60% by weight) and/or NiMo (0.1-60% by weight) ), and in a second step (d-2) in which the effluent from step (d-1) is hydrotreated at a temperature of 200 to 450°C, preferably of 250 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence of a second hydrotreatment catalyst, for example a NiMo type catalyst (0.1-60% by weight) and/ or CoMo (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 carried out in a single reactor with several catalytic beds placed in series with possibly additional hydrogen between the beds or in several reactors in series depending on the desired objective.

This hydrotreatment step can also have a demetallation, cracking and dearomatization function depending on 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 outlet of step (c). The feed for the hydrotreatment, containing at least part of the purified composition can be advantageously heated by a heat exchanger which is supplied by the effluent of the hydrotreatment (given that the hydrotreatment is exothermic, the effluent of hydrotreating will have a higher temperature than the feed entering the hydrotreating).

Preferably, the feed for the hydrotreatment, containing at least part of the purified composition, can be diluted with part of the hydrotreatment effluent, still having a temperature higher than the desired temperature at the inlet of the hydrotreatment. 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 charge.

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

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

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

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

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

The purified composition leaving step (c) or the effluent leaving step (d) of hydrotreatment optionally washed with water, can be fractionated into usable flows whose cutting points are typically chosen according to subsequent processing. This fractionation is carried out according to distillation temperature ranges, for example to separate streams such as LPG, gasoline, diesel, heavy fuel oil, kerosene, which can then be treated in a steam cracker and/or in a catalytic cracker and/or in a hydrocracker (then possibly in a steam cracker) and/or in a hydrotreatment reactor and/or used as such for the preparation of fuels, combustibles, lubricants or base oils. Those skilled in the art know how to select the cuts most suited to subsequent processing units depending on the desired objective.

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, diesel 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 most; preferably from 0.1% by weight to 25% by weight, even more preferably from 1% by weight to 20% by weight at the entrance to the following treatment.

Detailed description of the step optional steam cracking (e)

Steam cracking step (e) can be carried out on the purified composition of step (c) with or without dilution with a conventional steam cracking feed, or on the purified hydrotreated composition of step (d) with or without dilution. Prior to this step (e), a separation step by distillation can be implemented depending on the technology of the steam cracking furnaces.

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

Steam cracking step (e) consists of thermally cracking in one or more ovens a mixture of the purified composition and/or the purified and hydrotreated composition and water vapor at high temperatures of the order of 650 to 1000° C, preferably from 700 to 900°C, typically from 750 to 850°C, under low pressures (1 to 3 bars). The cracking reaction is carried out in the absence of oxygen. The reaction time is usually very short, of the order of a few hundred milliseconds. These conditions make it possible to break the carbon-carbon bonds and produce unsaturated hydrocarbons with molecules smaller than the charge introduced into the reactor(s). The effluents leaving the reactor(s) are then cooled quickly to temperatures of 400 to 550°C in order to limit secondary reactions such as polymerization of olefins, dienes and acetylenes. The cooled effluents are finally fractionated to recover light C2-C5 olefins, such as ethylene, propylene, butadiene, isobutene, n -butene and isoprene.

The purified composition of stage (c) or the purified and hydrotreated composition of stage (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) may also be mixed with naphtha, diesel or crude oil to obtain a plastic liquefaction oil concentration. purified ranging from 0.01% by weight to 50% by weight maximum; preferably from 0.1% by weight to 25% by weight, even more preferably from 1% by weight to 20% by weight at the inlet of the steam cracker. The purified composition is then converted into olefins, such as ethylene and propylene, as well as aromatics.

In a preferred embodiment, the purified composition, or purified and hydrotreated, can be sent at least partially directly into a steam cracker without any other dilution 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 of the steam cracker, in addition to the flow obtained by the inventive process, can be ethane, liquefied petroleum gas, naphtha or gas oils. Liquefied petroleum gas (LPG) is essentially made up of propane and butanes. Gas oils have a boiling range of approximately 200 to 350°C, and consist of C10 to C22 hydrocarbons, including predominantly linear and branched paraffins, cyclic paraffins and aromatics (including mono-, naphtho- and poly-aromatics).

In particular, the cracking products obtained at the outlet of the steam cracker may include ethylene, propylene and benzene, and optionally hydrogen, toluene, xylenes and 1,3-butadiene.

In a preferred embodiment, the outlet 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 outlet temperature can influence the content of high-value chemicals in the cracked products obtained by the present process.

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 carried out in the presence of water vapor in a ratio of 0.1 to 1.0 kg of steam per kg of hydrocarbon feed, preferably 0.25 to 0.7 kg of steam per kg of hydrocarbon feed in the steam cracker, preferably in a ratio of 0.35 kg of steam per kg of feed mixture, to obtain cracking products as defined above.

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

To the extent that 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 feed may be incomplete at the entrance to the reactors at the temperature where some hydrocarbon molecules begin to break down. The purified and/or purified and hydrotreated composition can then be preheated to a temperature at least 10°C below the decomposition temperature, then subjected to separation of the hydrocarbon vapors produced and the residual hydrocarbon liquid in a container of flash. In this flash container, the liquid exits from the bottom by gravity and the hydrocarbon vapors from the top. Optionally, the hydrocarbon liquid can be returned to the plastics liquefaction unit or to the optional hydrocracking stage.

Detailed description of the optional hydrocracking step

Prior to steam cracking step (e), the hydrotreated effluent 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 carried out at a temperature of 250 to 480°C, a partial pressure of hydrogen of 1.5 to 25 MPa abs. and an hourly volume velocity of 0.1 to 10h ^-1 .

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

In one embodiment, the hydrocracking step may be carried out by adding a hydrocracking catalyst bed downstream of the last hydrotreating catalyst bed of the hydrotreating section.

Description of figures

There describes a possible embodiment of the invention. In this possible embodiment, the plastic liquefaction oil (1) is first optionally pretreated in the pretreatment section (A) to be subjected to pretreatment (PTT) by (i) filtration, (ii ) washing with water or a polar solvent, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). The pretreated oil (2) is then sent to a cavitation treatment section (B) in the presence of a basic compound (3) implementing step (b) of the invention. The effluent (4) from step (b) can then be sent to a solids separation section (C). The effluent (5) leaving section (C) or the effluent (4) leaving section (B) is then sent to a separation section (D) implementing step (c) of this invention. When this section implements step (c2), the phase (9) containing the basic compound can be returned to the cavitation treatment section (B). The effluent (6) leaving the section (D), possibly after fractionation and/or dilution, can be sent to one or more of the following optional sections: an optional hydrotreatment section (HDT) (E), an optional section processing (SC) in a steam cracker (F), an optional processing section (HC) in a hydrocracker (G), an optional processing section (FCC) in a fluidized bed catalytic cracker (H), an optional section of treatment (HDT) in a hydrotreatment reactor (I), an optional preparation section (Pool) of a fuel or a lubricant or a base oil (J). The hydrotreatment section may include one or more hydrotreatment and/or selective hydrogenation units. Preferably, the effluent (7) leaving the hydrotreatment section (E) is then steam cracked to obtain olefins which can then be polymerized. Preferably, the effluent (7) leaving the hydrocracking section (E) is then steam cracked to obtain olefins which can then be polymerized.

Examples

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

Ex e simple 1 : Two-stage hydrotreating and steam cracking of an oil of liquefaction plastic

A purified plastic liquefaction oil leaving step (c) of the process according to the invention can be hydrotreated in two stages according to the following procedure:

The purified and washed liquefaction oil can be introduced into a first hydrotreatment section (HDT1) essentially to hydrogenate the diolefins and acetylenes. This step may include 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 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 olefins and demetallation (HDM), desulfurization (HDS), denitrogenation (HDN) and deoxygenation (HDO). These two sections consist of one or more reactors operated in series, or in parallel, or both. Isolated, lead-lag, series and/or parallel guard reactors can be considered depending on the nature and quantity of the contaminant in the flow to be treated.

In the event that the treatment according to the invention does not make it possible to obtain a sufficient reduction in impurities, guard reactors to eliminate chlorine, metals and silicon can be added. Silicon can also be trapped on the upper bed of a reactor in the HDT2 section or separately, upstream.

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

As the hydrotreating reactions in sections HDT1 and HDT2 are exothermic, quenching with cold hydrogen or dilution with an inert filler can be used to moderate the temperature rise and control the reaction. Dilution with an inert charge can be carried out by recycling the liquid fraction leaving the reactors.

There may be intermediate quenches 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 carried out to control the temperature. Strict control of the temperature in HDT1 must be carried out, in order to avoid blockage of the reactor and deterioration of the catalytic hydrogenation conditions.

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

Typical temperature range at the HDT1 inlet at the start of the cycle (SOR: start of run): 150-250°C. The catalyst for HDT 1 usually comprises Pd (0.1-10 wt%) and/or Ni (0.1-60 wt%) and/or NiMo (0.1-60 wt%).

Typical temperature range at the HDT2 inlet at the start of the cycle (SOR: start of run): 200-340°C. Typical HDT2 outlet temperature range (SOR): 300-380°C, up to 450°C. The catalyst for HDT 2 usually includes a NiMo (any type of commercial catalyst for refining or petrochemical application), potentially a CoMo in the very last beds at the bottom of the reactor (any type of commercial catalyst for refining or petrochemical application).

The upper bed of HDT2 should preferably be operated with a NiMo having a hydrogenating capacity as well as a silicon trapping capacity. An upper bed of this type can be considered as a metal trap also having HDM activity and hydrogenating capacity. It is possible to have two separate beds in an HDT2 reactor, with quenching between the two beds or between the two reactors, if the two beds are in two separate reactors, or no quenching at all. Ideally, the intermediate quenching is carried out using cold HDT2 effluent or by adding cold hydrogen, that is to say at a temperature generally ranging from 15 to 30°C, in order to control the exotherm. of HDT2.

Depending on the metals present in the liquefaction oil to be hydrotreated, a hydrodemetallation catalyst, for example commercial, can be added to the upper bed of the HDT2 section in order to protect the lower catalytic beds from deactivation.

The hydrotreated liquefaction oil leaving the HDT2 section, optionally after washing with water to remove inorganic compounds (hydrosulfide, hydrogen chloride, ammonia), can be used as is or fractionated according to temperature ranges of distillation, to feed a steam cracker, an FCC, a hydrocracker, a catalytic reformer or a pool of fuels such as LPG, gasoline, jet, 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, bringing the hydrotreated effluent into contact with a hydrocracking catalyst, in the presence of H ₂ to produce an effluent meeting the specifications of a steam cracker in terms of final boiling point (<370°C ).

Claims (16)

Process for purifying a composition comprising a plastic liquefaction oil comprising the following steps:
(a) providing a composition comprising a plastic liquefaction oil, said composition containing at least 20 ppm by mass of heteroatoms,
(b) treating the composition supplied in step (a) by hydrodynamic cavitation in the presence of a basic compound at a temperature of at most 350°C to obtain an effluent containing the modified composition,
(c) subjecting the effluent from step (b) to (c1) washing with water or a solvent immiscible with the modified composition, (c2) separation, or to the succession of steps (c2) and (c1), and obtain a purified composition having a reduced heteroatom content, and a phase containing the basic compound and heteroatoms initially contained in the modified composition. Process according to claim 1, in which step (b) is carried out in the presence of 0.1 to 50% m of basic compound relative to the total mass of the treated composition. Process according to claim 1 or 2, characterized in that prior to step (b) or during step (b), a solid basic compound is added to the composition of step a) (i), (ii) a basic compound previously dissolved in an aqueous medium, preferably water, or (iii) a basic compound previously dissolved in a solvent. A method according to any one of claims 1 to 3, wherein step (b) is characterized in that the basic compound comprises an oxide, a hydroxide, a bicarbonate or an alkoxide of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or bicarbonate of a quaternary ammonium cation, alone or in a mixture. Process according to any one of claims 1 to 4, in which step b) is characterized in that the basic compound is chosen from LiOH, NaOH, CsOH, Ba(OH) ₂ , Na ₂ O, KOH, K ₂ O, CaO, Ca(OH) ₂ , MgO, Mg(OH) ₂ , NH ₄ OH, TMAOH, TEAOH, TBuOH, MeONA, EtONa and their mixtures. Process according to any one of claims 1 to 5, characterized in that step (c) comprises at least the separation step (c2) to separate the phase containing the basic compound and heteroatoms, and the purified composition, and in that the phase containing the basic compound and heteroatoms is returned in whole or in part to step (b). Method according to any one of claims 1 to 6, characterized in that step (b) comprises one or more of the following characteristics:
- step b) is carried out at a temperature of 50 to 350°C, preferably 50 to 250°C, more preferably 90 to 200°C, more preferably 90 to 190°C,
- step (b) of hydrodynamic cavitation is carried out for a duration of 0.1 second to 2 hours, preferably 1 minute to 1 hour, more preferably 1 minute to 20 minutes or 1 minute to 16 minutes . Process according to any one of Claims 1 to 7, characterized in that step (c) is 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. Method according to any one of claims 1 to 8, characterized in that step c1) is carried out in the presence of water with a neutral, basic or acidic pH. Process according to any one of claims 1 to 9, characterized in that step c2) is carried out by (i) centrifugation, (ii) decantation, (iii) hydrocyclone or (iv) by the combination of two or three of these steps. Process according to any one of claims 1 to 10, in which, prior to the hydrodynamic cavitation treatment of step (b), said composition is subjected to (i) filtration, (ii) washing with water or a polar solvent immiscible with the composition, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). Method according to any one of claims 1 to 11, in which:
(d) the purified composition of step (c) undergoes one- or two-step catalytic hydrotreatment to provide a hydrotreated purified composition. Process according to claim 12, characterized in that the hydrotreatment of step (d):
- is carried out 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 bars, preferably 30 to 100 bars and in the presence of a hydrotreatment catalyst, or
- is carried out in a first step (d-1) in which the purified composition of step (c) is hydrotreated at a temperature of 80 to 250°C, preferably 130 to 250°C in the presence of hydrogen at an absolute pressure of 5 to 60 bars, preferably 20 to 45 bars and in the presence of a first hydrotreatment catalyst, and in a second step (d-2) in which the effluent from step (d-1) is hydrotreated at a temperature of 200 to 450°C, preferably 250 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence a second hydrotreatment catalyst. Process according to any one of claims 12 or 13, in which the purified and hydrotreated composition leaving step (d) is further washed with water to remove inorganic compounds such as hydrosulfide, chloride hydrogen, ammonia. Process according to any one of claims 1 to 14, in which the purified composition of step (c) or the hydrotreated purified composition of step (d) is
(f) used as such or separated into usable streams for the preparation of fuels such as LPG, gasoline, diesel, heavy fuel oil, kerosene and/or for the preparation of lubricants and/or base oils,
and/or treated, pure or diluted, optionally separated into usable streams, in:
(g) a steam cracker to produce olefins, and/or
(h) a fluidized bed catalytic cracker, and/or
(i) a hydrocracker, then optionally in a steam cracker, and/or
(j) a hydrotreatment reactor, in particular a catalytic hydrogenation reactor. Installation comprising an optional pretreatment section (A), a cavitation treatment section (B), an optional solids separation section (C), a separation section (D), an optional hydrotreatment section (E) and /or an optional treatment section in a steam cracker (F) and/or an optional treatment section in a hydrocracker (G) and/or an optional treatment section in a catalytic cracker in a fluidized bed (H) and/or a section optional treatment in a hydrotreatment reactor (I) and/or an optional section for preparing a fuel or a fuel, a lubricant or a base oil (J), in which the different sections are fluidly connected to implement the method according to any one of the preceding claims.