PROCESS FOR TREATING PLASTIC PYROLYSIS OILS INCLUDING A HYDROGENATION STAGE AND HOT SEPARATION

Abstract

The present invention relates to a process for treating a plastic pyrolysis oil, comprising:a) hydrogenation of said feedstock in a mixture with at least a portion of liquid effluent from step c) and in the presence of hydrogen and a catalyst at a temperature between 140 and 340°C;b) hydrotreatment of said hydrogenated effluent in the presence of hydrogen and a catalyst;c) separation of the hydrotreated effluent carried out at high temperature and high pressure to obtain a gaseous effluent and a liquid effluent, a portion of which is recycled upstream of step a),d) separation carried out at low temperature and high pressure and fed with the gaseous effluent and the other portion of the liquid effluent from step c) and an aqueous solution, to obtain a hydrocarbon effluent.

Description

Title of the invention: PROCESS FOR TREATING PLASTIC PYROLYSIS OILS INCLUDING A HYDROGENATION STAGE AND HOT SEPARATION Technical field

[0001] The present invention relates to a method for treating a plastic pyrolysis oil in order to obtain a hydrocarbon effluent which can be recovered in a gasoline, jet or diesel fuel storage unit or as a feedstock for a steam cracking unit. More particularly, the present invention relates to a method for treating a feedstock resulting from the pyrolysis of plastic waste in order to eliminate at least part of the impurities which said feedstock may contain in relatively large quantities. Prior art

[0002] Plastics from collection and sorting channels can undergo a pyrolysis step in order to obtain, among other things, pyrolysis oils. These plastic pyrolysis oils are generally burned to generate electricity and / or used as fuel in industrial or district heating boilers.

[0003] Another way of recovering plastic pyrolysis oils is the use of these plastic pyrolysis oils as a feedstock for a steam cracking unit in order to (re)create olefins, the latter being monomers constituting certain polymers. However, plastic waste is generally mixtures of several polymers, for example mixtures of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polystyrene. In addition, depending on the uses, plastics may contain, in addition to polymers, other compounds, such as plasticizers, pigments, dyes or even residues of polymerization catalysts. Plastic waste may also contain, to a minor extent, biomass originating for example from household waste.Waste treatment on the one hand, including storage, mechanical treatments, sorting, pyrolysis, and also the storage and transport of pyrolysis oil on the other hand can also induce corrosion. As a result, oils from the pyrolysis of plastic waste contain many impurities, in particular diolefins, metals, in particular iron, silicon, or halogenated compounds, in particular chlorine-based compounds, heteroelements such as sulfur, oxygen and nitrogen, insolubles, often at high levels and incompatible with steam cracking units or units located downstream of steam cracking units, in particular polymerization processes and processes. selective hydrogenation. These impurities can cause operability problems, including corrosion, coking, or catalytic deactivation problems, or incompatibility problems in the uses of the target polymers. The presence of diolefins can also lead to problems of instability of the pyrolysis oil, characterized by the formation of gums. Gums and insolubles that may be present in the pyrolysis oil can cause clogging problems in the processes.

[0004] Furthermore, during the steam cracking stage, the yields of light olefins sought for petrochemicals, in particular ethylene and propylene, depend heavily on the quality of the feedstocks sent to steam cracking. The BMCI (Bureau of Mines Correlation Index) is often used to characterize hydrocarbon cuts. This index, developed for hydrocarbon products derived from crude oils, is calculated from the measurement of the density and the average boiling point: it is equal to 0 for a linear paraffin and to 100 for benzene. Its value is therefore higher when the product analyzed has an aromatic condensed structure, naphthenes having a BMCI intermediate between paraffins and aromatics. Overall, the yields of light olefins increase when the paraffin content increases and therefore when the BMCI decreases.Conversely, the yields of undesired heavy compounds and / or coke increase when the BMCI increases.

[0005] Document WO 2018 / 055555 proposes a global, very general and relatively complex process for recycling plastic waste, ranging from the actual step of pyrolysis of the plastic waste to the steam cracking step. The process of application WO 2018 / 055555 comprises, among other things, a step of hydrotreatment of the liquid phase resulting directly from the pyrolysis, preferably under fairly advanced conditions, particularly in terms of temperature, for example at a temperature of between 260 and 300°C, a step of separation of the hydrotreatment effluent and then a step of hydrodealkylation of the separated heavy effluent at a preferably high temperature, for example of between 260 and 400°C.

[0006] Unpublished patent application FR 21 / 00.026 describes a method for treating plastic pyrolysis oil, comprising:

[0007] a) hydrogenation of said feedstock in the presence of at least hydrogen and at least one hydrogenation catalyst at an average temperature between 140 and 340°C, the outlet temperature of step a) is at least 15°C higher than the inlet temperature of step a), to obtain a hydrogenated effluent; b) hydrotreatment of said hydrogenated effluent in the presence of at least hydrogen and at least one hydrotreatment catalyst, to obtain a hydrotreated effluent, the average temperature of step b) being higher than the average temperature of step a); (c) a separation of the hydrotreated effluent in the presence of an aqueous stream, at a temperature between 50 and 370°C, to obtain at least one gaseous effluent, one aqueous liquid effluent and one hydrocarbon liquid effluent.

[0008] In this application FR 21 / 00.026, the hydrogenation of the diolefins and part of the hydrotreatment reactions, in particular part of the hydrogenation of the olefins and the hydrodemetallation reactions, in particular the retention of silicon, are carried out in the same step (step a) and at a temperature sufficient to limit the deactivation of the catalyst. This same step also makes it possible to benefit from the heat of hydrogenation reactions, in particular of part of the diolefins, so as to have a rising temperature profile in this step and thus being able to eliminate the need for a heating device between the catalytic hydrogenation section and the catalytic hydrotreatment section.

[0009] Temperature control is important in step a) and must respond to an opposing constraint. On the one hand, the temperature at the inlet and throughout the hydrogenation reaction section must be sufficiently low to allow the hydrogenation of the diolefins and olefins at the start of the hydrogenation reaction section. On the other hand, the temperature at the inlet of the hydrogenation reaction section must be sufficiently high to avoid deactivation of the catalyst. Since the hydrogenation reactions, in particular of a portion of the olefins and diolefins, are highly exothermic, a rising temperature profile is then observed in the hydrogenation reaction section. This higher temperature at the end of said section allows the hydrodemetallization and hydrodechlorination reactions to be carried out.

[0010] Thus, due to the highly exothermic nature of all the reactions implemented in this step a), controlling the temperature of the reaction medium proves to be very important because too high a temperature level promotes:

[0011] -self-maintenance, or even the runaway reactions due to thermal acceleration effect kinetics.

[0012] - undesirable side reactions, such as for example polymerization, coking of catalysts or cracking reactions.

[0013] It is known that recycling part of the product obtained to or upstream of at least one of the reaction steps advantageously makes it possible, on the one hand, to dilute the impurities and, on the other hand, to control the temperature in the reaction step(s), in which the reactions involved may be highly exothermic. Application FR 21 / 00.026 thus describes the possibility of recycling part of the product obtained after step c) of separation and washing with water (cold recycling).

[0014] The present invention provides an improvement to this principle of controlling exothermicity by recycling by proposing a process diagram for treating a load comprising a plastic pyrolysis oil, allowing, by implementing a recycle of hot liquid at the inlet of step a) of hydrogenation, precise control of temperatures, improved control of exothermicity and of the different reactions taking place in the different catalytic zones. Summary of the invention

[0015] More specifically, the invention relates to a method for treating a load comprising a plastic pyrolysis oil, comprising:

[0016] a) a hydrogenation step carried out in a hydrogenation reaction section, using at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst, said hydrogenation reaction section being supplied at least with said feedstock mixed with at least a portion of a liquid effluent from a separation step c) and a first gaseous stream comprising hydrogen, said hydrogenation reaction section being carried out at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrogenated effluent,

[0017] b) a hydrotreatment step carried out in a hydrotreatment reaction section, using at least one fixed bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreatment catalyst, said hydrotreatment reaction section being fed at least with said hydrogenated effluent from step a) and a second gas stream comprising hydrogen, said hydrotreatment reaction section being carried out at an average temperature between 250 and 430°C, a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrotreated effluent,

[0018] c) a separation step, fed with the hydrotreated effluent from step b), said step being carried out at a temperature between 200 and 450°C and at a pressure substantially identical to the pressure of step b) to obtain at least a first gaseous effluent, and the liquid effluent, part of which is recycled upstream of step a),

[0019] d) a separation step, fed with the first gaseous effluent and another part of the liquid effluent from step c) and an aqueous solution, said step being carried out at a temperature between 20 and less than 200°C, and at a pressure substantially identical to or lower than the pressure of step c), to obtain at least a second gaseous effluent, an aqueous effluent and a hydrocarbon effluent,

[0020] e) optionally a step of fractionating all or part of the hydrocarbon effluent from step d), to obtain at least a third gaseous effluent and at least a first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C,

[0021] f) optionally a hydrocracking step carried out in a hydrocracking reaction section, implementing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst,said hydrocracking reaction section being fed with at least a portion of said hydrocarbon effluent from step d) and / or with at least a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C from step e) and a third gas stream comprising hydrogen, said hydrocracking reaction section being carried out at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h 1 to obtain a first hydrocracked effluent.

[0022] One of the objectives of the present invention is to control the progress and the exothermicity of the reactions in step a) of hydrogenation, while ensuring the supply of heat necessary for the start-up and control of the different reactions and in particular the hydrogenation in step a) requiring specific temperature operating conditions.

[0023] Another objective of the present invention is to maximize energy recovery by recycling, hot and under high pressure, a portion of the liquid effluent from step c). Indeed, the energy to reach the inlet temperature required in step a) is at least partly provided by the heat of a portion of the liquid effluent from step c), which makes it possible to save costs but also to reduce CO2 emissions.

[0024] Mixing the feedstock and a portion of the liquid effluent upstream of step a) makes it possible to dilute the impurities in the feedstock but also to heat the feedstock indirectly. Indirect heating of the feedstock makes it possible to avoid direct heating above a temperature of 200°C in contact with a wall, which would cause hot spots in said feedstock, which would induce the formation of gums and / or coke and which would cause fouling and an increase in the pressure drop of the feedstock heating system as well as of the catalyst bed(s).

[0025] The present invention therefore relates to a hydrotreatment process flow diagram allowing simultaneous precise control of the reaction temperatures implemented in step a) of hydrogenation and more preferably the heating of the system indirectly, by implementing a hot liquid recycle upstream of step a) of hydrogenation.

[0026] Another advantage of the process according to the invention is to purify an oil resulting from the pyrolysis of plastic waste from at least part of its impurities, which makes it possible to hydrogenate it and thus to be able to recover it, in particular by incorporating it directly into the fuel storage unit or by making it compatible with treatment in a steam cracking unit in order to be able to obtain, in particular, light olefins with increased yields which can be used as monomers in the manufacture of polymers.

[0027] Another advantage of the invention is to prevent risks of blockage and / or corrosion of the treatment unit in which the method of the invention is implemented, the risks being exacerbated by the presence, often in significant quantities, of diolefins, metals and halogenated compounds in the plastic pyrolysis oil.

[0028] The method of the invention thus makes it possible to obtain a hydrocarbon effluent from a plastic pyrolysis oil freed at least in part from the impurities of the starting plastic pyrolysis oil, thus limiting the operability problems, such as corrosion, coking or catalytic deactivation problems, which these impurities can cause, in particular in the steam cracking units and / or in the units located downstream of the steam cracking units, in particular the polymerization and hydrogenation units. The elimination of at least part of the impurities from the oils resulting from the pyrolysis of plastic waste will also make it possible to increase the range of applications of the target polymers, the incompatibilities of use being reduced.

[0029] According to one variant, the method comprises the fractionation step e).

[0030] According to one variant, the process comprises the hydrocracking step f).

[0031] According to a variant, in step a) the hydrogen coverage is between 250 and 800 Nm3 of hydrogen per m3 of charge (Nm3 / m3).

[0032] According to a variant, at least part of the liquid effluent from separation step c) is preheated before being recycled upstream of hydrogenation step a).

[0033] According to a variant, the weight ratio between the liquid effluent from step c) recycled in step a) and the feedstock comprising a plastic pyrolysis oil is between 0.01 and 10.

[0034] According to a variant, the process comprises a step aO) of pretreatment of the feedstock comprising a plastic pyrolysis oil, said pretreatment step being carried out upstream of step a) of hydrogenation and comprises a filtration step and / or an electrostatic separation step and / or a step of washing using an aqueous solution and / or an adsorption step.

[0035] According to a variant, the hydrocarbon effluent from separation step d), or at least one of the two liquid hydrocarbon cuts from step e), is sent in whole or in part to a steam cracking step g) carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C and at a pressure between 0.05 and 0.3 MPa relative.

[0036] According to a variant, the reaction section of step a) uses at least two reactors operating in switchable mode.

[0037] According to a variant, a flow containing an amine and / or a sulfur compound is injected upstream of step a).

[0038] According to a variant, the gaseous effluent from steps c), d) and / or e), and / or the liquid effluent from step c) and / or the hydrocarbon effluent from step d) and / or the first and / or the second hydrocarbon cut from step e) is / are subjected to a heavy metal adsorption step.

[0039] According to a variant, said hydrogenation catalyst comprises a support chosen from alumina, silica, silica-aluminas, magnesia, clays and their mixtures and a hydro-dehydrogenating function comprising either at least one element from group VIII and at least one element from group VIB, or at least one element from group VIII.

[0040] According to a variant, said hydrotreatment catalyst comprises a support chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof, and a hydro-dehydrogenating function comprising at least one element from group VIII and / or at least one element from group VIB.

[0041] According to a variant, the method further comprises a second hydrocracking step f') carried out in a hydrocracking reaction section, using at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of the first hydrocracking effluent from the first hydrocracking step f) and a gas stream comprising hydrogen, said hydrocracking reaction section being carried out at a temperature between 250 and 450°C, a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a second hydrocracking effluent.

[0042] According to a variant, said hydrocracking catalyst comprises 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 group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and / or at least one metal from group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

[0043] The invention also relates to the product capable of being obtained, and preferably obtained by the process according to the invention.

[0044] According to this variant, the product comprises, relative to the total weight of the product: - a total content of metallic elements less than or equal to 10.0 ppm by weight, - including an iron element content less than or equal to 200 ppb by weight, and / or - a silicon element content less than or equal to 5.0 ppm by weight, and / or - a sulfur content less than or equal to 500 ppm by weight, and / or - a nitrogen content less than or equal to 100 ppm by weight, and / or - a chlorine element content less than or equal to 10 ppm by weight, and / or - a mercury content less than or equal to 5 ppb by weight.

[0045] According to the present invention, the pressures are absolute pressures, also noted abs., and are given in absolute MPa (or MPa abs.), unless otherwise indicated.

[0046] According to the present invention, the expressions "between ... and..." and "between .... and..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this were not the case and the limit values ​​were not included in the range described, such precision will be provided by the present invention.

[0047] In the sense of the present invention, the different parameter ranges for a given step such as pressure ranges and temperature ranges may be used alone or in combination. For example, in the sense of the present invention, a range of preferred pressure values ​​may be combined with a range of more preferred temperature values.

[0048] In the following, particular and / or preferred embodiments of the invention may be described. They may be implemented separately or combined with each other, without limitation of combination when this is technically feasible.

[0049] In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUP AC classification.

[0050] The metal content is measured by X-ray fluorescence. DETAILED DESCRIPTION The charge

[0051] According to the invention, a “plastic pyrolysis oil” is an oil, advantageously in liquid form at room temperature, resulting from the pyrolysis of plastics, preferably plastic waste originating in particular from collection and sorting channels. It can also be obtained from the pyrolysis of used tires.

[0052] It comprises in particular a mixture of hydrocarbon compounds, in particular paraffins, mono- and / or di-olefins, naphthenes and aromatics. At least 80% by weight of these hydrocarbon compounds preferably have a boiling point below 700°C, and preferably below 550°C. In particular, depending on the origin of the pyrolysis oil, it may comprise up to 70% by weight of paraffins, up to 90% by weight of olefins and up to 90% by weight of aromatics, it being understood that the sum of the paraffins, olefins and aromatics is 100% by weight of the hydrocarbon compounds.

[0053] The density of the pyrolysis oil, measured at 15°C according to the ASTM D4052 method, is generally between 0.75 and 0.99 g / cm3, preferably between 0.75 and 0.95 g / cm3.

[0054] The plastic pyrolysis oil may comprise, and most often also comprises, impurities such as metals, in particular iron, silicon, halogenated compounds, in particular chlorinated compounds. These impurities may be present in the plastic pyrolysis oil at high levels, for example up to 350 ppm by weight or 700 ppm by weight or even 1000 ppm by weight of halogenated elements (in particular chlorine) provided by halogenated compounds, and up to 100 ppm by weight or even 200 ppm by weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, poor metals and metalloids may be assimilated to contaminants of a metallic nature, called metals or metallic or semi-metallic elements.In particular, the metals or metallic or semi-metallic elements, possibly contained in the oils resulting from the pyrolysis of plastic waste, include silicon, iron or both of these elements. The plastic pyrolysis oil may also include other impurities such as heteroelements provided in particular by sulfur compounds, oxygenated compounds and / or nitrogen compounds, at contents generally less than 10,000 ppm by weight of heteroelements and preferably less than 4,000 ppm by weight of heteroelements. The plastic pyrolysis oil may also include other impurities such as heavy metals such as mercury, arsenic, zinc and lead, for example up to 100 ppb by weight or even 200 ppb by weight of mercury.

[0055] The feedstock of the process according to the invention comprises at least one plastic pyrolysis oil. Said feedstock may consist solely of plastic pyrolysis oil(s). Preferably, said feedstock comprises at least 50% by weight, preferably between 70 and 100% by weight, of plastic pyrolysis oil relative to the total weight of the feedstock, i.e. preferably between 50 and 100% by weight, preferably between 70% and 100% by weight of plastic pyrolysis oil.

[0056] The feedstock of the process according to the invention may comprise, in addition to the plastic pyrolysis oil or oils, a conventional petroleum feedstock or a feedstock resulting from the conversion of biomass which is then co-treated with the pyrolysis oil. of plastics from the load.

[0057] The conventional petroleum feedstock may advantageously be a cut or a mixture of cuts of the naphtha, diesel or vacuum diesel type.

[0058] The feedstock resulting from the conversion of biomass may advantageously be chosen from vegetable oils, algae or algal oils, fish oils, used edible oils, and fats of vegetable or animal origin; or mixtures of such feedstocks. Said vegetable oils may advantageously be crude or refined, totally or partially, and derived from plants chosen from rapeseed, sunflower, soybean, palm, olive, coconut, copra, castor oil, cotton, peanut, linseed and crambe oils and all oils derived for example from sunflower or rapeseed by genetic modification or hybridization, this list not being limiting. Said animal fats are advantageously chosen from lard and fats composed of residues from the food industry or from the catering industries.Frying oils, various animal oils such as fish oils, tallow, lard can also be used.

[0059] The feedstock from biomass conversion may also be selected from feedstocks from thermal or catalytic biomass conversion processes, such as oils that are produced from biomass, particularly lignocellulosic biomass, with various liquefaction methods, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to material derived from recently living organisms, which includes plants, animals and their by-products. The term "lignocellulosic biomass" refers to biomass derived from plants or their by-products. Lignocellulosic biomass is composed of carbohydrate polymers (cellulose, hemicellulose) and an aromatic polymer (lignin).

[0060] The feedstock resulting from the conversion of biomass can also advantageously be chosen from feedstocks resulting from the paper industry.

[0061] The plastic pyrolysis oil can come from a thermal or catalytic pyrolysis treatment or can be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen). Pre-treatment (optional)

[0062] Said feedstock comprising a plastic pyrolysis oil can advantageously be pretreated in an optional pretreatment step aO), prior to step a) of hydrogenation, to obtain a pretreated feedstock which feeds step a).

[0063] This optional pretreatment step aO) makes it possible to reduce the quantity of contaminants and solid particles, in particular the quantity of iron and / or silicon and / or chlorine, possibly present in the feed comprising a plastic pyrolysis oil. Thus, an optional pretreatment step aO) of the feed comprising a plastic pyrolysis oil is advantageously carried out in particular when said feed comprises more than 10 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 50 ppm by weight of metallic elements and / or solid particles, and in particular when said feed comprises more than 5 ppm by weight of silicon, more particularly more than 10 ppm by weight, or even more than 20 ppm by weight of silicon. Similarly, an optional step aO) of pretreatment of the feed comprising a plastic pyrolysis oil is advantageously carried out in particular when said feed comprises more than 10 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 50 ppm by weight of chlorine.

[0064] Said optional pretreatment step aO) can be implemented by any method known to those skilled in the art making it possible to reduce the quantity of contaminants. It can in particular comprise a filtration step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step.

[0065] Said optional pretreatment step aO) is advantageously carried out at a temperature between 0 and 150°C, preferably between 5 and 100°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 1.0 MPa abs.

[0066] According to a variant, said optional pretreatment step aO) is carried out in an adsorption section operated in the presence of at least one adsorbent, preferably of the alumina type, having a specific surface area greater than or equal to 100 m2 / g, preferably greater than or equal to 200 m2 / g. The specific surface area of ​​said at least one adsorbent is advantageously less than or equal to 600 m2 / g, in particular less than or equal to 400 m2 / g. The specific surface area of ​​the adsorbent is a surface area measured by the BET method, i.e. the specific surface area determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938).

[0067] Advantageously, said adsorbent comprises less than 1% by weight of metallic elements, preferably is free of metallic elements. By metallic elements of the adsorbent, it is meant the elements of groups 6 to 10 of the periodic table of elements (new IUP AC classification). The residence time of the load in the adsorption section is generally between 1 and 180 minutes.

[0068] Said adsorption section of the optional step aO) comprises at least one adsorption column, preferably comprises at least two adsorption columns, preferably between two and four adsorption columns, containing said adsorbent. When the adsorption section comprises two adsorption columns, an operating mode may be an operation called "swing", according to the established Anglo-Saxon term, in which one of the columns is in line, that is to say in operation, while the other column is in reserve. When the absorbent in the online column is spent, this column is isolated while the reserve column is brought online, i.e., in operation. The spent absorbent can then be regenerated in situ and / or replaced with fresh absorbent so that the column containing it can be brought back online once the other column has been isolated.

[0069] Another mode of operation is to have at least two columns operating in series. When the absorbent in the column placed at the head is worn, this first column is isolated and the worn absorbent is either regenerated in situ or replaced with fresh absorbent. The column is then put back online in the last position and so on. This operation is called permutable mode, or according to the English term "PRS" for Permutable Reactor System or "lead and lag" according to the English term. The association of at least two adsorption columns makes it possible to overcome the possible and possibly rapid poisoning and / or clogging of the adsorbent under the joint action of metallic contaminants, diolefins, gums from diolefins and insolubles possibly present in the pyrolysis oil of plastics to be treated.The presence of at least two adsorption columns facilitates the replacement and / or regeneration of the adsorbent, advantageously without stopping the pretreatment unit, or even the process, thus reducing the risks of clogging and therefore avoiding stopping the unit due to clogging, controlling costs and limiting adsorbent consumption.

[0070] According to another variant, said optional pretreatment step aO) is implemented in a washing section with an aqueous solution, for example water or an acidic or basic solution. This washing section may comprise equipment for bringing the feedstock into contact with the aqueous solution and separating the phases so as to obtain the pretreated feedstock on the one hand and the aqueous solution comprising impurities on the other hand. Among this equipment, there may be for example a stirred reactor, a decanter, a mixer-decanter and / or a co- or counter-current washing column.

[0071] Said optional pretreatment step aO) may also optionally be supplied with at least a portion of the liquid effluent from step c) of the process and / or a portion of the first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C from step e) and / or a portion of the second hydrocarbon cut comprising compounds having a boiling point greater than 175°C from step e), in a mixture or separately from the feedstock comprising a plastic pyrolysis oil. The recycling of at least a portion of the liquid effluent from step c) makes it possible in particular to increase sedimentation and therefore, after possible filtration, to improve the pretreatment of the feedstock.

[0072] Said optional pretreatment step aO) thus makes it possible to obtain a pretreated feedstock which then feeds the hydrogenation step a). Step a) of hydrogenation

[0073] According to the invention, the method comprises a hydrogenation step a) implemented in a hydrogenation reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst, said hydrogenation reaction section being fed at least with said feedstock, optionally pretreated, in a mixture with at least a portion of liquid effluent from step c) and a first gaseous stream comprising hydrogen, said hydrogenation reaction section being implemented at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrogenated effluent.

[0074] Step a) is in particular carried out under hydrogen pressure and temperature conditions allowing the hydrogenation of the diolefins and olefins to be carried out at the start of the hydrogenation reaction section while allowing, by a rising temperature profile, the hydrodemetallation and hydrodechlorination to be carried out, in particular at the end of the hydrogenation reaction section. A necessary quantity of hydrogen is injected so as to allow the hydrogenation of at least a portion of the diolefins and olefins present in the plastic pyrolysis oil, the hydrodemetallation of at least a portion of the metals, in particular the retention of silicon, and also the conversion of at least a portion of the chlorine (into HCl).The hydrogenation of diolefins and olefins thus makes it possible to avoid or at least limit the formation of "gums", i.e. the polymerization of diolefins and olefins and therefore the formation of oligomers and polymers, which can block the reaction section of hydrotreatment step b). In parallel with the hydrogenation, hydrodemetallation, and in particular the retention of silicon during step a), makes it possible to limit the catalytic deactivation of the reaction section of hydrotreatment step b). In addition, the conditions of step a) make it possible to convert at least part of the chlorine.

[0075] Temperature control is important in this step and must respond to an opposing constraint. On the one hand, the temperature at the inlet and throughout the hydrogenation reaction section must be sufficiently low to allow the hydrogenation of the diolefins and olefins at the start of the hydrogenation reaction section. On the other hand, the temperature at the inlet of the hydrogenation reaction section must be sufficiently high to avoid deactivation of the catalyst. Since the hydrogenation reactions, in particular of a portion of the olefins and diolefins, are highly exothermic, a rising profile of the temperature in the hydrogenation reaction section. This higher temperature at the end of said section allows the hydrodemetallization and hydrodechlorination reactions to be carried out. Thus, the temperature at the outlet of the reaction section of step a) is higher than the temperature at the inlet of the reaction section of step a), generally by at least 3°C, preferably by at least 5°C.

[0076] The temperature in step a), whether it is the average temperature (WABT), the temperature at the inlet of the reaction section or the rise in temperature in step a) between the inlet and outlet of the reaction section, can in particular be controlled by the recycle rate of a portion of the liquid effluent from step c) and / or by the temperature of the recycled effluent.

[0077] The temperature difference between the inlet and the outlet of the reaction section of step a) is understood to mean injection of a gaseous (hydrogen) or liquid cooling flow, in particular a portion of the liquid effluent from step c).

[0078] The temperature difference between the inlet and the outlet of the reaction section of step a) is exclusively due to the exothermicity of the chemical reactions carried out in the reaction section and therefore does not include the use of a heating means (furnace, heat exchanger, etc.).

[0079] The temperature at the inlet of the reaction section of step a) is between 135 and 397°C, preferably between 240 and 347°C.

[0080] The temperature at the outlet of the reaction section of step a) is between 138 and 400°C, preferably between 243 and 350°C.

[0081] According to the invention, it is advantageous to carry out the hydrogenation of the diolefins and part of the hydrodemetallation reactions in the same step and at a temperature sufficient to limit the deactivation of the catalyst of step a) which is manifested by a reduction in the conversion of the diolefins. This same step also makes it possible to benefit from the heat of hydrogenation reactions, in particular of part of the olefins and diolefins, so as to have a rising temperature profile in this step and thus being able to eliminate the need for a heating device between the catalytic hydrogenation section and the catalytic hydrotreatment section.

[0082] Said reaction section carries out a hydrogenation in the presence of at least one hydrogenation catalyst, advantageously at an average temperature (or WABT as defined below) between 140 and 400°C, preferably between 240 and 350°C, and particularly preferably between 260 and 330°C, a hydrogen partial pressure between 1.0 and 10.0 MPa abs, preferably between 1.5 and 8.0 MPa abs. and at an hourly volumetric flow rate (WH) between 0.1 and 10.0 h1, preferably between 0.2 and 5.0 h1, and very preferably between 0.3 and 3.0 h1.

[0083] According to the invention, the “average temperature” of a reaction section corresponds to the Weight Average Bed Temperature (WABT) according to the English term consecrated Saxon, well known to those skilled in the art. The average temperature is advantageously determined according to the catalytic systems, the equipment, and their configuration, used. The average temperature (or WABT) is calculated as follows:

[0084] [Math.l] WABT “ (Xrtj®

[0085] with Tinput: the temperature of the effluent at the inlet of the reaction section and Toutput: the temperature of the effluent at the outlet of the reaction section. Unless otherwise indicated, the “average temperature” of a reaction section is given at start-of-cycle conditions.

[0086] The hourly volumetric flow rate (WH) is defined here as the ratio between the hourly volumetric flow rate of the feedstock comprising the plastic pyrolysis oil, possibly pretreated, by the volume of catalyst(s).

[0087] The hydrogen coverage is defined as the ratio of the volume flow rate of hydrogen taken under normal temperature and pressure conditions compared to the volume flow rate of “fresh” feedstock, i.e. the feedstock to be treated, possibly pretreated, without taking into account a recycled fraction, and in particular without taking into account the liquid effluent from step c) recycled, at 15°C (in normal m3, noted Nm3, of H2 per m3 of feedstock).

[0088] The quantity of the gas flow comprising hydrogen (H2), feeding said reaction section of step a), is advantageously such that the hydrogen coverage is between 100 and 1500 Nm3 of hydrogen per m3 of feed (Nm3 / m3), preferably between 200 and 1000 Nm3 of hydrogen per m3 of feed (Nm3 / m3), more preferably between 250 and 800 Nm3 of hydrogen per m3 of feed (Nm3 / m3).

[0089] Advantageously, the reaction section of said step a) comprises between 1 and 5 reactors, preferably between 2 and 5 reactors, and particularly preferably it comprises two reactors. The advantage of a hydrogenation reaction section comprising several reactors lies in an optimized treatment of the feedstock, while making it possible to reduce the risks of clogging of the catalytic bed(s) and therefore to avoid stopping the unit due to clogging.

[0090] According to a preferred variant, these reactors operate in permutable mode, called according to the English term "PRS" for Permutable Reactor System or "lead and lag". The association of at least two reactors in PRS mode makes it possible to isolate a reactor, to unload the spent catalyst, to reload the reactor with fresh catalyst and to put said reactor back into service without stopping the process. The PRS technology is described, in particular, in patent FR2681871.

[0091] According to a particularly preferred variant, the reaction section hydrogenation of step a) comprises two reactors operating in switchable mode.

[0092] Advantageously, reactor internals, for example of the filter tray type, can be used to prevent clogging of the reactor(s). An example of a filter tray is described in patent FR3051375.

[0093] Advantageously, said hydrogenation catalyst comprises a support, preferably mineral, and a hydro-dehydrogenating function.

[0094] According to a variant, the hydro-dehydrogenating function comprises in particular at least one element from group VIII, preferably chosen from nickel and cobalt, and at least one element from group VIB, preferably chosen from molybdenum and tungsten. According to this variant, the total content expressed as oxides of the metal elements from groups VIB and VIII is preferably between 1% and 40% by weight, preferably from 5% to 30% by weight relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0095] The weight ratio expressed in metal oxide between the metal (or metals) of group VIB relative to the metal (or metals) of group VIII is preferably between 1 and 20, and preferably between 2 and 10.

[0096] According to this variant, the reaction section of said step a) comprises for example a hydrogenation catalyst comprising between 0.5% and 12% by weight of nickel, preferably between 0.9% and 10% by weight of nickel (expressed as nickel oxide NiO relative to the weight of said catalyst), and between 1% and 30% by weight of molybdenum, preferably between 3% and 20% by weight of molybdenum (expressed as molybdenum oxide MoO3 relative to the weight of said catalyst) on a preferably mineral support, preferably on an alumina support.

[0097] According to another variant, the hydro-dehydrogenating function comprises, and is preferably constituted of, at least one element from group VIII, preferably nickel. According to this variant, the content of nickel oxides is preferably between 1 and 50% by weight, preferably between 10% and 30% by weight relative to the weight of said catalyst. This type of catalyst is preferably used in its reduced form, on a preferably mineral support, preferably on an alumina support.

[0098] The support of said hydrogenation catalyst is preferably chosen from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof. Said support may contain doping compounds, in particular oxides chosen from boron oxide, in particular boron trioxide, zirconia, ceria, titanium oxide, phosphoric anhydride and a mixture of these oxides. Preferably, said hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and possibly boron. When phosphoric anhydride P2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. When boron trioxide B2O3 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may be, for example, a y (gamma) or q (eta) alumina.

[0099] Said hydrogenation catalyst is for example in the form of extrudates.

[0100] Very preferably, step a) can implement in addition to the ca(s) hydrogenation catalysts described above furthermore at least one hydrogenation catalyst used in step a) comprising less than 1% by weight of nickel and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, expressed as nickel oxide NiO relative to the weight of said catalyst, and less than 5% by weight of molybdenum and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, expressed as molybdenum oxide MoO3 relative to the weight of said catalyst, on an alumina support. This catalyst with a low metal content can preferably be placed upstream or downstream of the hydrogenation catalyst(s) described above.

[0101] Said hydrogenation step a) makes it possible to obtain a hydrogenated effluent, that is to say an effluent with a reduced content of olefins, in particular diolefins, and metals, in particular silicon. The content of impurities, in particular diolefins, in the hydrogenated effluent obtained at the end of step a) is reduced compared to that of the same impurities, in particular diolefins, included in the feedstock of the process. Hydrogenation step a) generally makes it possible to convert at least 40%, and preferably at least 60% of the diolefins as well as at least 40%, and preferably at least 60% of the olefins contained in the initial feedstock. The heat released by the saturation of the double bonds makes it possible to raise the temperature of the reaction medium and to initiate the hydrotreatment reactions, in particular the elimination, at least in part, of other contaminants, such as silicon and chlorine.Preferably, at least 50%, and more preferably at least 75% of the chlorine and silicon of the initial charge are removed during step a). The hydrogenated effluent obtained at the end of step a) of hydrogenation is sent, preferably directly, to step b) of hydrotreatment. Step b) of hydrotreatment

[0102] According to the invention, the treatment method comprises a hydrotreatment step b) implemented in a hydrotreatment reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreatment catalyst, said hydrotreatment reaction section being fed at least by said hydrogenated effluent from step a) and a second gas stream comprising hydrogen, said hydrotreatment reaction section being carried out at an average temperature between 250 and 430°C, a partial hydrogen pressure between 1.0 and 10.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrotreated effluent.

[0103] Advantageously, step b) implements hydrotreatment reactions well known to those skilled in the art, and more particularly hydrotreatment reactions such as the hydrogenation of aromatics, hydrodesulfurization and hydrodenitrogenation. In addition, the hydrogenation of the remaining olefins and halogenated compounds as well as the hydrodemetalation are continued.

[0104] Said hydrotreatment reaction section is advantageously carried out at a pressure equivalent to that used in the reaction section of hydrogenation step a), and generally at a higher average temperature than that of the reaction section of hydrogenation step a). Thus, said hydrotreatment reaction section is advantageously carried out at an average hydrotreatment temperature between 250 and 430°C, preferably between 280 and 380°C, at a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and at an hourly volumetric flow rate (WH) between 0.1 and 10.0 h1, preferably between 0.1 and 5.0 h1, preferentially between 0.2 and 2.0 h1, more preferably between 0.2 and 1 h '.The hydrogen coverage in step b) is advantageously between 100 and 1500 Nm3 of hydrogen per m3 of fresh feedstock that feeds step a), and preferably between 200 and 1000 Nm3 of hydrogen per m3 of fresh feedstock that feeds step a), preferably between 250 and 800 Nm3 of hydrogen per m3 of fresh feedstock that feeds step a). The definitions of the average temperature (WABT), the WH and the hydrogen coverage correspond to those described above.

[0105] Said hydrotreatment reaction section is fed at least by said hydrogenated effluent from step a) and a second gaseous stream comprising hydrogen, advantageously at the level of the first catalytic bed of the first reactor in operation. Optionally, the reaction section of said step b) may also be further fed by at least a portion of the liquid effluent from step c).

[0106] Advantageously, said step b) is carried out in a hydrotreatment reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, more preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrotreatment catalysts. When a reactor comprises several catalytic beds, that is to say at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are preferably arranged in series in said reactor.

[0107] When step b) is implemented in a hydrotreatment reaction section comprising several, preferably two, reactors, these reactors can operate in series and / or in parallel and / or in permutable mode (or PRS) and / or in “swing” mode. The various possible operating modes, PRS mode (or lead and lag) and swing mode, are well known to those skilled in the art and are advantageously defined above.

[0108] In another embodiment of the invention, said hydrotreatment reaction section comprises a single fixed bed reactor containing n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, more preferably between two and five.

[0109] In a particularly preferred embodiment, the hydrogenation reaction section of step a) comprises two reactors operating in permutable mode followed by the hydrotreatment reaction section of step b) which comprises a single fixed-bed reactor.

[0110] Advantageously, said hydrotreatment catalyst used in said step b) may be chosen from known hydrodemetallization, hydrotreatment and silicon capture catalysts, used in particular for the treatment of petroleum fractions, and combinations thereof. Known hydrodemetallization catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known hydrotreatment catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976. Known silicon capture catalysts are, for example, those described in patent applications CN 102051202 and US 2007 / 080099.

[0111] In particular, said hydrotreatment catalyst comprises a support, preferably mineral, and at least one metallic element having a hydro-dehydrogenating function. Said metallic element having a hydro-dehydrogenating function advantageously comprises at least one element from group VIII, preferably chosen from the group consisting of nickel and cobalt, and / or at least one element from group VIB, preferably chosen from the group consisting of molybdenum and tungsten. The total content expressed as oxides of the metallic elements from groups VIB and VIII is preferably between 0.1% and 40% by weight, preferably from 5% to 35% by weight, relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively. tively. The weight ratio expressed as metal oxide between the metal (or metals) of group VIB relative to the metal (or metals) of group VIII is preferably between 1.0 and 20, preferably between 2.0 and 10. For example, the hydrotreatment reaction section of step b) of the process comprises a hydrotreatment catalyst comprising between 0.5% and 10% by weight of nickel, preferably between 1% and 8% by weight of nickel, expressed as nickel oxide NiO relative to the total weight of the hydrotreatment catalyst, and between 1.0% and 30% by weight of molybdenum, preferably between 3.0% and 29% by weight of molybdenum, expressed as molybdenum oxide MoO3 relative to the total weight of the hydrotreatment catalyst, on a mineral support, preferably on an alumina support.

[0112] The support of said hydrotreatment catalyst is advantageously chosen from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof. Said support may also contain doping compounds, in particular oxides chosen from boron oxide, in particular boron trioxide, zirconia, ceria, titanium oxide, phosphoric anhydride and a mixture of these oxides. Preferably, said hydrotreatment catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron. When phosphoric anhydride P2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina.When boron trioxide B2O3 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may be, for example, a y (gamma) or q (eta) alumina.

[0113] Said hydrotreatment catalyst is for example in the form of extrudates.

[0114] Advantageously, said hydrotreatment catalyst used in step b) of the process has a specific surface area greater than or equal to 250 m2 / g, preferably greater than or equal to 300 m2 / g. The specific surface area of ​​said hydrotreatment catalyst is advantageously less than or equal to 800 m2 / g, preferably less than or equal to 600 m2 / g, in particular less than or equal to 400 m2 / g. The specific surface area of ​​the hydrotreatment catalyst is measured by the BET method, i.e. the specific surface area determined by nitrogen adsorption in accordance with ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938). Such a specific surface area makes it possible to further improve the removal of contaminants, in particular metals such as silicon.

[0115] According to another aspect of the invention, the hydrotreatment catalyst as described above further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such a catalyst is often referred to as an "additive catalyst". Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or compounds including a furan cycle or sugars.

[0116] Advantageously, the hydrotreatment step b) allows the hydrogenation of at least 80%, and preferably of all of the olefins remaining after the hydrogenation step a), but also the conversion at least in part of other impurities present in the feedstock, such as aromatic compounds, metallic compounds, sulfur compounds, nitrogen compounds, halogenated compounds (in particular chlorinated compounds), oxygenated compounds. Preferably, the nitrogen content at the outlet of step b) is less than 100 ppm by weight. Step b) can also make it possible to further reduce the contaminant content, such as that of metals, in particular the silicon content. Preferably, the metal content at the outlet of step b) is less than 10 ppm by weight, and preferably less than 2 ppm by weight, and the silicon content is less than 5 ppm by weight.

[0117] Depending on the content of sulfur compounds in the initial feedstock to be treated, a stream containing a sulfurizing agent may be injected upstream of hydrogenation step a) and / or hydrotreatment step b) and / or upstream of one of the hydrocracking steps when they are present, preferably upstream of hydrogenation step a) and / or hydrotreatment step b) in order to ensure a sufficient quantity of sulfur to form or maintain the active species of the catalyst (in sulfur form). This activation or sulfurization step is carried out by methods well known to those skilled in the art, and advantageously under a sulfide-reducing atmosphere in the presence of hydrogen and hydrogen sulfide.The sulfurizing agents are preferably H2S gas, elemental sulfur, CS2, mercaptans, sulfides and / or polysulfides, hydrocarbon cuts with a boiling point below 400°C containing sulfur compounds or any other compound containing sulfur used for activating hydrocarbon feedstocks in order to sulfurize the catalyst. Said sulfur-containing compounds are advantageously chosen from alkyl disulfides such as, for example, dimethyl disulfide (DMDS), alkyl sulfides, such as, for example, dimethyl sulfide, thiols such as, for example, n-butyl mercaptan (or 1-butanethiol) and polysulfide compounds of the tert-onylpolysulfide type. The catalyst may also be sulfurized by the sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfurized in situ in the presence of a sulfurizing agent and a hydrocarbon feedstock.Very preferably, the catalyst is sulfurized in situ in the presence of the additive charge of dimethyl disulfide. Step c) separation

[0118] According to the invention, the treatment method comprises a separation step c), fed with the hydrotreated effluent from step b), said step being carried out at a temperature between 200 and 450°C and at a pressure substantially identical to the pressure of step b) to obtain at least a first gaseous effluent, and the liquid effluent, part of which is recycled upstream of step a).

[0119] The separation step c) is a so-called high pressure or medium pressure high temperature separation step, also known to those skilled in the art under the name HHPS (for "Hot High Pressure Separator" according to English terminology). Thus, this step c) preferably uses a so-called "hot high pressure" separator, the pressure being substantially equal to the operating pressure of step b). The term "pressure substantially equal to the pressure of step b)" means the pressure of step b) with a pressure difference of between 0 and 1 MPa, preferably of between 0.005 and 0.3 MPa, and particularly preferably of between 0.01 and 0.2 MPa relative to the pressure of step b). Preferably, the pressure of step c) is the pressure of step b) less the pressure losses.

[0120] The temperature at which the separation is carried out is between 200 and 450°C, preferably between 220 and 330°C, and particularly preferably between 240 and 300°C. According to a preferred variant, and with a view to recovering the most calories, the separation is carried out at the highest possible temperature but less than or equal to the outlet temperature of step b), which makes it possible to avoid or limit reheating (and therefore a need for calories) of the effluent from step b). According to another variant, the effluent from step b) can be reheated or cooled before separation.

[0121] Advantageously, the quantity of liquid effluent from step c) recycled, i.e. the fraction of product obtained recycled, is adjusted so that the weight ratio between the recycle stream from step c) and the feed comprising a plastic pyrolysis oil, i.e. the feed to be treated feeding the overall process, is less than or equal to 10, preferably less than or equal to 7, and preferably greater than or equal to 0.001, preferably greater than or equal to 0.01, and preferably greater than or equal to 0.1. Preferably, the quantity of liquid effluent from step c) recycled is adjusted so that the weight ratio between the recycle stream and the feed comprising a plastic pyrolysis oil is between 0.01 and 10, preferably between 0.1 and 7, and particularly preferably between 0.2 and 5. This recycle rate makes it possible to control the rise in temperature in step a).Indeed, when the recycle rate is high, the dilution rate of the feedstock is high, and the temperature rise at the start of the reaction section of step a), in particular due to the hydrogenation reactions of the diolefins, is thus controllable by the effect of . dilution.

[0122] The separation step can advantageously be implemented by any method known to those skilled in the art such as, for example, the combination of one or more separator(s) (balloon(s)), and / or one or more stripping column(s), this or these separator(s) (balloon(s)) and / or columns optionally being able to be supplied with a stripping gas, for example a hydrogen-rich gas stream. Preferably, step c) is implemented with a single separator (balloon).

[0123] The high pressure and high temperature separation makes it possible on the one hand to maximize energy recovery by hot recycling of a portion of the liquid effluent. Indeed, the energy to reach the necessary inlet temperature in step a) is at least partly provided by the heat of a portion of the liquid effluent from step c) and also makes it possible to reduce or even eliminate any preheating by direct heating of the feedstock beyond a temperature above 200°C to avoid the formation of gums. In addition, recycling at least a portion of the high pressure liquid effluent makes it possible to save energy for its pressurization in step a).

[0124] The high pressure and high temperature separation also makes it possible to minimize the quantity of light fraction (hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C or naphtha) contained in the liquid effluent recycled in step a). At this temperature, almost all of the light fraction of the effluent (naphtha) leaves as gaseous effluent to the separation / washing step d) while in the liquid phase we have mainly the heavy fraction of the feed (hydrocarbon cut comprising compounds having a boiling point greater than 175°C or middle distillates). In this way, ppH2 is favored in step a) because the light fraction (naphtha) could partially vaporize and lower the ppH2 if it were not at least partially eliminated during the high pressure and high temperature separation.The removal of the light fraction comprising naphtha may optionally be increased by slight expansion upstream of at least one separator implemented in step c) even if this implementation is not preferred due to the energy loss linked to the expansion. Another option for increasing the removal of the light fraction comprising naphtha may consist of carrying out stripping, for example by injecting a hydrogen-rich gas into step c).

[0125] According to a preferred variant, at least a portion of the hydrotreated liquid effluent from step c) can advantageously be either cooled, or preheated, if necessary, or kept at the same temperature as at the outlet of separation step c), before being recycled upstream of hydrogenation step a), depending on the temperature and the flow rate of feedstock and hydrogen, so that the temperature of the incoming stream, comprising said feedstock mixed with at least a portion of said liquid effluent from step c) and a hydrogen-rich gas, between 140 and 400°C, preferably between 220 and 350°C, and particularly preferably between 260 and 330°C.

[0126] In the case where at least a portion of the liquid effluent from separation step c) is preheated before being recycled upstream of hydrogenation step a), said effluent optionally passes through at least one exchanger and / or at least one furnace before being recycled upstream of hydrogenation step a), so as to adjust the temperature of said recycled liquid effluent.

[0127] In the case where at least a portion of the liquid effluent from separation step c) is cooled before being recycled upstream of hydrogenation step a), said effluent optionally passes through at least one exchanger and / or at least one air cooler before being recycled upstream of hydrogenation step a), so as to adjust the temperature of said recycled liquid effluent.

[0128] The implementation of the recycle upstream of the hydrogenation step a), of at least a part of the liquid effluent from step c) which can be either cooled or preheated, if necessary, or kept at the same temperature as at the outlet of the separation step c), therefore makes it possible to adjust the temperature of the flow entering step a), as required.

[0129] According to a variant, the feedstock, before being mixed with at least a portion of the effluent from step c), may be preheated by direct heating to a temperature of up to 200°C, preferably up to 180°C, and particularly preferably up to 150°C. Above this temperature, contact with a wall during direct heating may induce the formation of gums and / or coke, which may cause fouling and an increase in the pressure drop of the feedstock heating system and of the catalyst bed(s). Heating the feedstock to a temperature above 150°C, preferably above 180°C, and particularly preferably above 200°C is preferably carried out by indirect heating with at least a portion of the effluent from step c).

[0130] Thus, the temperature rise above 150°C, preferably above 180°C and particularly preferably above 200°C of the load is caused by mixing with a hotter liquid, and not by contact with a heated wall. This makes it possible to locally limit high temperatures. Indeed, during heating in a heat exchanger or in a furnace, to reach a given set temperature T, the temperature on the hot side must imperatively be higher than T in order to carry out the heat transfer economically. It is well known to those skilled in the art that the heat flow through a wall depends firstly on the temperature difference on either side of said wall and on the exchange surface. A small temperature difference between the cold and hot sides will imply, for a given quantity of heat exchanged, a larger exchange surface.This results in a temperature of the wall in contact with the cold fluid higher than the temperature . desired temperature commonly called skin temperature. Heating by mixing with a hot fluid thus makes it possible to avoid the skin temperature effect and therefore to limit high temperature zones. This type of heating by mixing with an inert hot liquid therefore makes it possible to limit undesirable reactions such as the polymerization of diolefins (gum formation) and / or the formation of coke, and to adjust the inlet temperature of the flow in step a) so as to initiate the hydrogenation reaction of the unsaturations, preferably at the lowest possible temperature, while controlling the exothermicity of these reactions by a dilution effect of the reactive species.

[0131] According to another variant, the load is entirely heated by indirect heating by at least part of the effluent from step c). In this case, the load is not preheated before being mixed with at least part of the effluent from step c).

[0132] The energy required for the reaction and more precisely, the adjustment of the minimum temperature required for the activation of the saturation reactions of the double bonds is therefore mainly achieved by mixing, upstream of step a), said feedstock comprising a plastic pyrolysis oil and a hydrogen-rich gas, with recycling of a portion of the liquid effluent from separation step c), having optionally undergone a temperature adjustment and preferably having been either preheated or cooled and particularly preferably having been preheated.

[0133] Another heating stream advantageously consists of a hydrogen-rich gaseous effluent originating from the hydrogen make-up and / or the gaseous effluent from separation step d). At least a portion of this hydrogen-rich gaseous effluent originating from the hydrogen make-up and / or the gaseous effluent from separation step d) is advantageously injected in a mixture with at least a portion of the liquid effluent from step c) or separately, upstream of step a). The hydrogen-rich gaseous stream can therefore advantageously be either preheated in a mixture with at least a portion of the liquid effluent or preheated separately before mixing, preferably by optionally passing through at least one exchanger and / or at least one furnace or any other heating means known to those skilled in the art. Step d) separation

[0134] According to the invention, the treatment method comprises a separation step d), advantageously implemented in at least one washing / separation section, supplied with the first gaseous effluent and another part of the liquid effluent from step c) and an aqueous solution, said step being carried out at a temperature between 20 and less than 200°C, and at a pressure substantially identical to or lower than the pressure of step c), to obtain at least a second gaseous effluent, an aqueous effluent and a hydrocarbon effluent.

[0135] The separation step d) is carried out in at least one so-called high pressure or medium pressure low temperature separator tank, also known to those skilled in the art as CHPS (for "Cold High Pressure Separator" according to English terminology). Thus, this step d) preferably uses a so-called "cold high pressure" separator, the pressure being substantially equal to the operating pressure of step c). The term "pressure substantially equal to the pressure of step c)" means the pressure of step c) with a pressure difference of between 0 and 1 MPa, preferably of between 0.005 and 0.3 MPa, and particularly preferably of between 0.01 and 0.2 MPa relative to the pressure of step c). Preferably, the pressure of step d) is the pressure of step c) less the pressure losses.Carrying out at least part of separation step d) at a pressure substantially identical to the operating pressure of step c) also facilitates the recycling of hydrogen.

[0136] The separation step d) can also be carried out at a pressure lower than the pressure of step c).

[0137] The separation step d) may also comprise a (first) separation step at a pressure substantially equal to the operating pressure of step c), followed by at least one other separation step carried out at an identical or lower temperature and at a lower pressure than each separation step of the preceding step d).

[0138] The temperature at which the separation of step d) is carried out is between 20 and less than 200°C, preferably between 25 and 120°C, and particularly preferably between 30 and 70°C.

[0139] It is important to operate in this temperature range (and therefore not to cool the hydroconverted effluent too much) to avoid the risk of blockage in the lines due to the precipitation of ammonium chloride salts.

[0140] The washing / separation section of step d) may at least partly be carried out in common or separate washing and separation equipment, this equipment being well known (separator drums which can operate at different pressures and temperatures, pumps, heat exchangers, washing columns, etc.). The separation step d) may for example comprise a column for stripping acid water (also called "sour water stripper" according to English terminology) from the withdrawn aqueous fraction, an acid gas washing column to purify the hydrogen-rich gas before recycling, a column for stabilizing the washed liquid effluent to remove the dissolved gases.

[0141] When one (or two) hydrocracking stages are present (described below), this stage d) can additionally be fed with at least a portion of the hydrocracking effluent from an optional hydrocracking stage.

[0142] The gaseous effluent obtained at the end of step d) advantageously comprises: hydrogen, preferably comprises at least 80% by volume, preferably at least 85% by volume, of hydrogen. Advantageously, said gaseous effluent may at least partly be recycled to steps a) of hydrogenation and / or b) of hydrotreatment and / or to one or more steps f) of hydrocracking when they are present, the recycling system being able to comprise a purification section.

[0143] The gaseous effluent may also be subject to additional separation(s) in order to recover at least one hydrogen-rich gas and / or light hydrocarbons, in particular ethane, propane and butane, which may advantageously be sent separately or as a mixture to one or more furnaces of the steam cracking step g) so as to increase the overall yield of olefins.

[0144] The aqueous effluent obtained at the end of step d) advantageously comprises ammonium salts and / or hydrochloric acid.

[0145] This separation step d) makes it possible in particular to eliminate the ammonium chloride salts, which are formed by reaction between the chloride ions, released by the hydrogenation of the chlorinated compounds in HCl form, in particular during steps a) and b) then dissolution in water, and the ammonium ions, generated by the hydrogenation of the nitrogen compounds in the form of NH3, in particular during step b) and / or supplied by injection of an amine then dissolution in water, and thus to limit the risks of blockage, in particular in the transfer lines and / or in the sections of the process of the invention and / or the transfer lines to the steam cracker, due to the precipitation of the ammonium chloride salts. It also makes it possible to eliminate the hydrochloric acid formed by the reaction of the hydrogen ions and the chloride ions.

[0146] Depending on the content of chlorinated compounds in the initial feedstock to be treated, a stream containing an amine such as, for example, monoethanolamine, diethanolamine and / or monodiethanolamine may be injected upstream of each catalytic step, preferably upstream of hydrogenation step a) and / or hydrotreatment step b), preferably upstream of hydrogenation step a) in order to ensure a sufficient quantity of ammonium ions to combine the chloride ions formed during the hydrotreatment step, thus making it possible to limit the formation of hydrochloric acid and thus to limit corrosion downstream of the separation section.

[0147] Advantageously, separation step d) comprises an injection of an aqueous solution, preferably an injection of water, into the mixture of the gaseous effluent and another part of the liquid effluent from step c), upstream of the washing / separation section, so as to dissolve at least in part ammonium chloride salts and / or hydrochloric acid and thus improve the elimination of chlorinated impurities and reduce the risks of blockages due to an accumulation of ammonium chloride salts.

[0148] In a possible embodiment of the invention, step d) of separation comprises the injection of an aqueous solution into the mixture of the gaseous effluent and another part of the liquid effluent from step c), followed by the washing / separation section advantageously comprising a separation phase making it possible to obtain at least one aqueous effluent loaded with ammonium salts, a washed liquid hydrocarbon effluent and a partially washed gaseous effluent. The aqueous effluent loaded with ammonium salts and the washed liquid hydrocarbon effluent can then be separated in a settling tank in order to obtain said hydrocarbon effluent and said aqueous effluent.Said partially washed gaseous effluent may in parallel be introduced into a washing column where it circulates countercurrently to an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrotreated effluent, which makes it possible to eliminate at least in part, preferably in full, the hydrochloric acid contained in the partially washed gaseous effluent and thus to obtain said gaseous effluent, preferably essentially comprising hydrogen, and an acidic aqueous stream. Said aqueous effluent from the settling tank may optionally be mixed with said acidic aqueous stream, and be used, optionally in a mixture with said acidic aqueous stream in a water recycling circuit to supply step d) of separation into said aqueous solution upstream of the washing / separation section and / or into said aqueous stream in the washing column.Said water recycling circuit may include a water top-up and / or a basic solution and / or a purge to evacuate dissolved salts.

[0149] The hydrocarbon effluent from separation step d) is sent, in part or in whole, either directly to the inlet of a steam cracking unit, or to an optional fractionation step e). Preferably, the liquid hydrocarbon effluent is sent, in part or in whole, preferably in whole, to a fractionation step e). Step e) (optional) of splitting

[0150] The process according to the invention may comprise a step of fractionating all or part, preferably all, of the hydrocarbon effluent from step d), to obtain at least one third gaseous stream and at least two liquid hydrocarbon streams, said two liquid hydrocarbon streams being at least a first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C (naphtha cut), in particular between 80 and 175°C, and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C (middle distillate cut).

[0151] Step e) makes it possible in particular to eliminate gases dissolved in the liquid hydrocarbon effluent, such as for example ammonia, hydrogen sulfide and light hydrocarbons having 1 to 4 carbon atoms.

[0152] The optional fractionation step e) is advantageously carried out at a pressure less than or equal to 1.0 MPa abs., preferably between 0.1 and 1.0 MPa abs.

[0153] According to one embodiment, step e) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit comprising a reflux drum. Said stripping column is fed with the liquid hydrocarbon effluent from step d) and with a stream of water vapor. The liquid hydrocarbon effluent from step d) can optionally be reheated before entering the stripping column. Thus, the lightest compounds are entrained at the top of the column and into the reflux circuit comprising a reflux drum in which a gas / liquid separation takes place. The gaseous phase which comprises the light hydrocarbons is withdrawn from the reflux drum, in a gas stream. The hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C is advantageously withdrawn from the reflux drum.The hydrocarbon fraction comprising compounds having a boiling point above 175°C is advantageously withdrawn at the bottom of the stripping column.

[0154] According to other embodiments, fractionation step e) may implement a stripping column followed by a distillation column or only a distillation column.

[0155] The first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C and the second hydrocarbon cut comprising compounds having a boiling point greater than 175°C, optionally mixed, may be sent, in whole or in part, to a steam cracking unit, at the end of which olefins may be (re)formed to participate in the formation of polymers. Preferably, only a portion of said cuts is sent to a steam cracking unit; at least a fraction of the remaining portion is optionally recycled in at least one of the steps of the process and / or sent to a fuel storage unit, for example a naphtha storage unit, a diesel storage unit or a kerosene storage unit, derived from conventional petroleum feedstocks.

[0156] According to a preferred embodiment, the first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C, all or part, is sent to a steam cracking unit, while the second hydrocarbon cut comprising compounds having a boiling point greater than 175°C is sent to a hydrocracking step and / or sent to a fuel storage unit.

[0157] In a particular embodiment, the optional fractionation step e) can make it possible to obtain, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point less than or equal to 175°C, preferably between 80 and 175°C, and a middle distillate cut comprising compounds having a boiling point greater than 175°C and less than 385°C, and a hydrocarbon cut comprising compounds having a boiling point greater than or equal to 385°C, called heavy hydrocarbon cut. The naphtha cut can be sent, in whole or in part, to a steam cracking unit and / or to the naphtha storage unit from conventional petroleum feedstocks, it can still be recycled; the middle distillate cut can also be, in whole or in part, either sent to a steam cracking unit, or to a diesel storage unit from conventional petroleum feedstocks, or even be recycled; the heavy cut can be sent, at least in part, to a steam cracking unit, or be sent to the hydrocracking stage when it is present.

[0158] In another particular embodiment, the optional fractionation step e) can make it possible to obtain, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point less than or equal to 175°C, preferably between 80 and 175°C, and a kerosene cut comprising compounds having a boiling point greater than 175°C and less than or equal to 280°C, a diesel cut comprising compounds having a boiling point greater than 280°C and less than 385°C and a hydrocarbon cut comprising compounds having a boiling point greater than or equal to 385°C, called a heavy hydrocarbon cut. The naphtha cut, the kerosene cut and / or the diesel cut may be, in whole or in part, either sent to a steam cracking unit, or respectively to a naphtha, kerosene or diesel pool from conventional petroleum feedstocks, or recycled.The heavy cut can be sent, at least in part, to a steam cracking unit, or sent to the hydrocracking stage when it is present.

[0159] In another particular embodiment, the naphtha cut comprising compounds having a boiling point less than or equal to 175°C from step e) is fractionated into a heavy naphtha cut comprising compounds having a boiling point between 80 and 175°C and a light naphtha cut comprising compounds having a boiling point less than 80°C, at least a portion of said heavy naphtha cut being sent to an aromatic complex comprising at least one step of reforming the naphtha in order to produce aromatic compounds. According to this embodiment, at least a portion of the light naphtha cut is sent to the steam cracking step g) described below.

[0160] The gas fraction(s) from fractionation step d) may be subject to additional purification(s) and separation(s) in order to recover at least light hydrocarbons, in particular ethane, propane and butane, which may advantageously be sent separately or as a mixture to one or more furnaces of steam cracking step g) so as to increase the overall yield of olefins. (Optional) hydrocracking step f)

[0161] According to a variant, the process of the invention may comprise a hydrocracking step f) carried out after the separation step d) with at least a portion of said hydrocarbon effluent from step d) or carried out after the fractionation step e) with at least a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C.

[0162] Advantageously, step f) implements the hydrocracking reactions well known to those skilled in the art, and more particularly makes it possible to convert heavy compounds, for example compounds having a boiling point above 175°C into compounds having a boiling point less than or equal to 175°C contained in the hydrocarbon effluent from fractionation step e). Other reactions, such as the hydrogenation of olefins, aromatics, hydrodemetallation, hydrodesulfurization, hydrodenitrogenation, etc. can continue.

[0163] Compounds with a boiling point above 175°C have a high BMCI and contain, compared to lighter compounds, more naphthenic, naphtheno-aromatic and aromatic compounds, thus leading to a higher C / H ratio. This high ratio is a cause of coking in the steam cracker, thus requiring steam cracking furnaces dedicated to this cut. When it is desired to minimize the yield of these heavy compounds (middle distillate cut) and maximize the yield of light compounds (naphtha cut), these compounds can be transformed at least in part into light compounds by hydrocracking, a cut generally favored for a steam cracking unit.

[0164] Thus, the process of the invention may comprise a hydrocracking step f) implemented in a hydrocracking reaction section, implementing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of said hydrocarbon effluent from step d) and / or with at least a portion of the second hydrocarbon cut comprising compounds having a boiling point greater than 175°C from step e) and a third gas stream comprising hydrogen, said hydrocracking reaction section being implemented at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h 1 to obtain a first hydrocracked effluent.

[0165] Thus, said hydrocracking reaction section is advantageously carried out at an average temperature between 250 and 480°C, preferably between 320 and 450°C, at a hydrogen partial pressure between 1.5 and 20.0 MPa abs., preferably between 3 and 18.0 MPa abs., and at an hourly volumetric flow rate (WH) between 0.1 and 10.0 h1, preferably between 0.1 and 5.0 h1, preferentially between 0.2 and 4 h1. The coverage in hydrogen in step c) is advantageously between 80 and 2000 Nm3 of hydrogen per m3 of fresh feed which feeds step a), and preferably between 200 and 1800 Nm3 of hydrogen per m3 of fresh feed which feeds step a). The definitions of the average temperature (WABT), the WH and the hydrogen coverage correspond to those described above.

[0166] Advantageously, said hydrocracking reaction section is implemented at a pressure equivalent to that used in the reaction section of hydrogenation step a) or hydrotreatment step b).

[0167] Advantageously, said step f) is carried out in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrocracking catalysts. When a reactor comprises several catalytic beds, i.e. at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are preferably arranged in series in said reactor.

[0168] The hydrocracked effluent may at least partly be recycled in the hydrogenation step a) and / or in the hydrotreatment step b) and / or in the separation step d). Preferably, it is recycled in the separation step d).

[0169] The hydrocracking step can be carried out in one (step f) or two steps (step f) and f')). When it is carried out in two steps, a separation of the effluent from the first hydrocracking step f) is carried out, making it possible to obtain a hydrocarbon cut comprising compounds having a boiling point above 175°C (middle distillate cut), which is introduced into the second hydrocracking step f') comprising a second dedicated hydrocracking reaction section, different from the first hydrocracking reaction section f). This configuration is particularly suitable when it is desired to produce only a naphtha cut.

[0170] The second hydrocracking step f') implemented in a hydrocracking reaction section, implementing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of the first hydrocracked effluent from the first hydrocracking step f) and a gas stream comprising hydrogen, said hydrocracking reaction section being implemented at an average temperature between 250 and 450°C, a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a second hydrocracked effluent. The preferred operating conditions and catalysts used in the second hydrocracking stage are those described for the first hydrocracking stage. The operating conditions and catalysts used in the two hydrocracking stages may be the same or different.

[0171] Said second hydrocracking step is preferably carried out in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, more preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrocracking catalyst(s).

[0172] These operating conditions used in the hydrocracking step(s) generally make it possible to achieve conversions per pass, into products having at least 80% by volume of compounds having boiling points less than or equal to 175°C, preferably less than 160°C and more preferably less than 150°C, greater than 15% by weight and even more preferably between 20 and 95% by weight. When the process is carried out in two hydrocracking stages, the conversion per pass in the second stage is kept moderate in order to maximize the selectivity into compounds of the naphtha cut (having a boiling point less than or equal to 175°C, in particular between 80°C and less than or equal to 175°C). The conversion per pass is limited by the use of a high recycle rate on the loop of the second hydrocracking stage.This rate is defined as the ratio between the feed flow rate of step f') and the flow rate of the load of step a), preferably this ratio is between 0.2 and 4, preferably between 0.5 and 2.5.

[0173] The hydrocracked effluent from the second hydrocracking stage f') can at least partly be recycled into the hydrogenation stage a) and / or into the hydrotreatment stage b and / or into the separation stage d). Preferably, it is recycled into the separation stage d).

[0174] The hydrocracking step(s) thus do not necessarily allow all the hydrocarbon compounds having a boiling point above 175°C (middle distillate cut) to be transformed into hydrocarbon compounds having a boiling point less than or equal to 175°C (naphtha cut). After the fractionation step e), there may therefore remain a more or less significant proportion of compounds having a boiling point above 175°C. To increase the conversion, at least a portion of this unconverted cut may be introduced into a second hydrocracking step f'). Another portion may be purged. Depending on the operating conditions of the process, said purge may be between 0 and 10% by weight of the cut comprising compounds having a boiling point above 175°C relative to the incoming feed, and preferably between 0.5% and 5% by weight.

[0175] According to the invention, the hydrocracking step(s) operate(s) in the presence of at least one hydrocracking catalyst.

[0176] The hydrocracking catalyst(s) used in the hydrocracking step(s) are conventional hydrocracking catalysts known to those skilled in the art, of the bifunctional type combining an acid function with a hydro-dehydrogenating function and optionally at least one binding matrix. The acid function is provided by supports with a large surface area (generally 150 to 800 m2 / g) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites. The hydro-dehydrogenating function is provided by at least one metal from group VIB of the periodic table and / or at least one metal from group VIII.

[0177] Preferably, the hydrocracking catalyst(s) comprise a hydro-dehydrogenating function comprising at least one metal from group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, and preferably from cobalt and nickel. Preferably, said catalyst(s) also comprise at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and preferably from molybdenum and tungsten. Hydro-dehydrogenating functions of the NiMo, NiMoW, NiW type are preferred.

[0178] Preferably, the content of group VIII metal in the hydrocracking catalyst(s) is advantageously between 0.5 and 15% by weight and preferably between 1 and 10% by weight, the percentages being expressed as a percentage by weight of oxides relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively.

[0179] Preferably, the content of group VIB metal in the hydrocracking catalyst(s) is advantageously between 5 and 35% by weight, and preferably between 10 and 30% by weight, the percentages being expressed as a percentage by weight of oxides relative to the total weight of the catalyst. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0180] The hydrocracking catalyst(s) may also optionally comprise at least one promoter element deposited on the catalyst and chosen from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (chlorine, fluorine preferred), optionally at least one element from group VIIB (manganese preferred), and optionally at least one element from group VB (niobium preferred).

[0181] Preferably, the hydrocracking catalyst(s) comprise at least one amorphous or poorly crystallized porous mineral matrix of oxide type chosen from aluminas, silicas, silica-aluminas, aluminates, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, clay, alone or in mixture, and preferably aluminas or silica-aluminas, alone or in mixture.

[0182] Preferably, the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina.

[0183] Preferably, the hydrocracking catalyst(s) also optionally comprise a zeolite chosen from Y zeolites, preferably from US Y zeolites, alone or in combination, with other zeolites from beta zeolites, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, alone or as a mixture. Preferably, the zeolite is USY zeolite alone.

[0184] In the case where said catalyst comprises a zeolite, the zeolite content in the hydrocracking catalyst(s) is advantageously between 0.1 and 80% by weight, preferably between 3 and 70% by weight, the percentages being expressed as a percentage of zeolite relative to the total weight of the catalyst.

[0185] A preferred catalyst comprises, and preferably consists of, at least one group VIB metal and optionally at least one non-noble group VIII metal, at least one promoter element, and preferably phosphorus, at least one Y zeolite and at least one alumina binder.

[0186] An even more preferred catalyst comprises, and preferably consists of, nickel, molybdenum, phosphorus, a USY zeolite, and optionally also a beta zeolite, and alumina.

[0187] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, alumina and silica-alumina.

[0188] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0189] Said hydrocracking catalyst is for example in the form of extrudates.

[0190] In a variant, the hydrocracking catalyst used in the second hydrocracking step comprises a hydro-dehydrogenating function comprising at least one noble metal from group VIII chosen from palladium and platinum, alone or as a mixture. The content of noble metal from group VIII is advantageously between 0.01 and 5% by weight and preferably between 0.05 and 3% by weight, the percentages being expressed as a percentage by weight of oxides (PtO or PdO) relative to the total weight of the catalyst.

[0191] According to another aspect of the invention, the hydrocracking catalyst further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such a catalyst is often referred to as an "additive catalyst". Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic, alcohol, thiol function, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or compounds including a furanic cycle or sugars.

[0192] The preparation of catalysts for the hydrogenation, hydrotreatment and hydrocracking steps is known and generally comprises a step of impregnation of the metals of group VIII and group VIB when present, and optionally phosphorus and / or boron on the support, followed by drying, then optionally calcination. In the case of an additive catalyst, the preparation is generally carried out by simple drying without calcination after introduction of the organic compound. Here, calcination is understood to mean a heat treatment under a gas containing air or oxygen at a temperature greater than or equal to 200°C. Before their use in a step of the process, the catalysts are generally subjected to sulfurization in order to form the active species. The catalyst of step a) may also be a catalyst used in its reduced form, thus involving a reduction step in its preparation.

[0193] The gas stream comprising hydrogen, which feeds the hydrogenation, hydrotreatment and hydrocracking reaction section, may consist of a hydrogen make-up and / or recycled hydrogen originating in particular from separation step d). Preferably, an additional gas stream comprising hydrogen is advantageously introduced at the inlet of each reactor, in particular operating in series, and / or at the inlet of each catalytic bed from the second catalytic bed of the reaction section. These additional gas streams are also called cooling streams. They make it possible to control the temperature in the reactor in which the reactions carried out are generally very exothermic.

[0194] Said hydrocarbon effluent or said hydrocarbon stream(s) thus obtained by treatment according to the process of the invention of a plastic pyrolysis oil, has(have) a composition compatible with the specifications of an input charge of a steam cracking unit. In particular, the composition of the hydrocarbon effluent or of said hydrocarbon stream(s) is preferably such that: - the total content of metallic elements is less than or equal to 10.0 ppm by weight, preferably less than or equal to 2.0 ppm by weight, preferably less than or equal to 1.0 ppm by weight and preferably less than or equal to 0.5 ppm by weight, with: a silicon (Si) element content of less than or equal to 5.0 ppm by weight, preferably less than or equal to 1 ppm by weight, and preferably less than or equal to 0.6 ppm by weight and / or an iron (Fe) element content of less than or equal to 200 ppb by weight, - the sulfur content is less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight, and / or - the nitrogen content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight and more preferably less than or equal to 5 ppm by weight and / or - the asphaltene content is less than or equal to 5.0 ppm by weight, and / or - the total chlorine element content is less than or equal to 10 ppm by weight, preferably less than 1.0 ppm by weight, and / or - a mercury content of less than or equal to 5 ppb by weight, preferably less than 3 ppb by weight, and / or - the content of olefinic compounds (mono- and di-olefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, more preferably less than or equal to 0.1% by weight. The contents are given in relative weight concentrations, percentage (%) by weight, part(s) per million (ppm) by weight or part(s) per billion (ppb) by weight, relative to the total weight of the flow considered.

[0195] The process according to the invention therefore makes it possible to treat plastic pyrolysis oils to obtain an effluent which can be injected, in whole or in part, into a steam cracking unit. (Optional) heavy metal adsorption step

[0196] Any gaseous effluent and / or any liquid effluent from at least one of the separation steps c) and d) or from the fractionation step e) may be subjected to an optional heavy metal adsorption step.

[0197] The gaseous effluents may in particular be the first gaseous effluent from step c) and / or the second gaseous effluent from step d) and / or the third gaseous effluent from step e).

[0198] The liquid effluents may in particular be the liquid effluent from step c) and / or the hydrocarbon effluent from step d) and / or the first and / or the second hydrocarbon cut from step e).

[0199] The optional adsorption step makes it possible to eliminate or reduce the quantity of metallic impurities, in particular the quantity of heavy metals such as arsenic, zinc, lead, and in particular mercury, possibly present in said gaseous and liquid effluents. The metallic impurities, and in particular the heavy metals, are present in the feedstock. Certain impurities, in particular mercury-based, can be transformed in one of the steps of the process according to the invention. Their transformed form is easier to trap. Their elimination or reduction may in particular be necessary when at least part of said gaseous and liquid effluents is intended to be sent, either directly or after having undergone one or more optional additional steps such as the fractionation step e), to a step having severe metallic impurity specifications, such as a steam cracking step.

[0200] Thus, an optional step of adsorption of a gaseous effluent from steps c), d) and / or e) and / or of the liquid effluent from step c) and / or of the hydrocarbon effluent from step d) and / or the first and / or the second hydrocarbon cut from step e) is advantageously carried out in particular when at least one of these effluents or the feed respectively comprises more than 20 ppb by weight, in particular more than 15 ppb by weight of heavy metal metallic elements (As, Zn, Pb, Hg, etc.), and in particular when at least one of these effluents or the feed respectively comprises more than 10 ppb by weight of mercury, more particularly more than 15 ppb by weight of mercury.

[0201] Said optional adsorption step is advantageously carried out at a temperature between 20 and 150°C, preferably between 40 and 100°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 1.0 MPa abs.

[0202] Said optional adsorption step can be implemented by any adsorbent known to those skilled in the art making it possible to reduce the quantity of such contaminants.

[0203] According to a variant, said optional adsorption step is implemented in an adsorption section operated in the presence of at least one adsorbent comprising a porous support and at least one active phase which may be based on sulfur in the elemental form, or in the form of metal sulfide or metal oxide, or even in metallic form in elemental form.

[0204] The porous support can be chosen indifferently from the families of aluminas, silica-aluminas, silicas, zeolites, activated carbons. Advantageously, the porous support is based on alumina. The specific surface area of ​​the support is generally between 150 and 600 m2 / g, preferably between 200 and 400 m2 / g, even more preferably between 150 and 320 m2 / g. The specific surface area of ​​the adsorbent is a surface area measured by the BET method as described above.

[0205] The active phase is based on sulfur in elemental form, or in the form of metal sulfide or metal oxide, or even in metallic form in elemental form. Preferably, the active phase is in the form of metal sulfide, in particular a sulfide of a metal from the group chosen from copper, molybdenum, tungsten, iron, nickel or cobalt.

[0206] Advantageously, the active phase of the adsorbent comprises between 1 and 70% by weight of sulfur relative to the total weight of the adsorbent, preferably between 2 and 25% and very preferably between 3 and 20%.

[0207] Advantageously, the proportion by weight of metal relative to the total weight of the adsorbent is generally between 1 and 60%, preferably between 2 and 40%, preferably between 5 and 30%, very preferably between 5 and 20%.

[0208] The residence time in the adsorption section is generally between 1 and 180 minutes.

[0209] Said adsorption section may comprise one or more adsorption columns. When the adsorption section comprises two adsorption columns, one operating mode may be a so-called "swing" operation, in which one of the columns is online, i.e. in operation, while the other column is in reserve. Another operating mode is to have at least two columns operating in series in a switchable mode.

[0210] Preferably, said adsorption section comprises an adsorption column for the gaseous effluent(s) and an adsorption column for the liquid effluent(s). Step g) of steam cracking (optional)

[0211] The hydrocarbon effluent from separation step d), or at least one of the two liquid hydrocarbon streams from optional step e), may be sent in whole or in part to a steam cracking step g).

[0212] Advantageously, the gas fraction(s) resulting from separation step d) and / or fractional step e) and containing ethane, propane and butane, may also be sent in whole or in part to steam cracking step g).

[0213] Said steam cracking step g) is advantageously carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C, preferably between 750 and 850°C, and at a pressure between 0.05 and 0.3 MPa relative. The residence time of the hydrocarbon compounds is generally less than or equal to 1.0 seconds (denoted s), preferably between 0.1 and 0.5 s. Advantageously, water vapor is introduced upstream of the optional steam cracking step g) and after the separation (or fractionation). The quantity of water introduced, advantageously in the form of water vapor, is advantageously between 0.3 and 3.0 kg of water per kg of hydrocarbon compounds at the inlet of step e). Preferably, the optional step g) is carried out in several pyrolysis furnaces in parallel so as to adapt the operating conditions to the different flows feeding step g), in particular from step e), and also to manage the decoking times of the tubes.A furnace comprises one or more tubes arranged in parallel. A furnace may also refer to a group of furnaces operating in parallel. For example, a furnace may be dedicated to cracking the hydrocarbon fraction comprising compounds having a boiling point less than or equal to 175°C.

[0214] The effluents from the various steam cracking furnaces are generally recombined before separation in order to constitute an effluent. It is understood that the steam cracking step g) comprises the steam cracking furnaces but also the sub-steps associated with steam cracking well known to those skilled in the art. These sub-steps may include in particular heat exchangers, columns and catalytic reactors and recycling to the furnaces. A column generally makes it possible to fractionating the effluent in order to recover at least one light fraction comprising hydrogen and compounds having 2 to 5 carbon atoms, and one fraction comprising pyrolysis gasoline, and optionally one fraction comprising pyrolysis oil. Columns are used to separate the various constituents of the light fractionation fraction in order to recover at least one cut rich in ethylene (C2 cut) and one cut rich in propylene (C3 cut) and optionally one cut rich in butenes (C4 cut). Catalytic reactors are used in particular to carry out hydrogenations of the C2, C3 or even C4 cuts and of the pyrolysis gasoline. Saturated compounds, in particular saturated compounds having 2 to 4 carbon atoms, are advantageously recycled to the steam cracking furnaces so as to increase the overall olefin yields.

[0215] This steam cracking step g) makes it possible to obtain at least one effluent containing olefins comprising 2, 3 and / or 4 carbon atoms (i.e. C2, C3 and / or C4 olefins), at satisfactory contents, in particular greater than or equal to 30% by weight, in particular greater than or equal to 40% by weight, or even greater than or equal to 50% by weight of total olefins comprising 2, 3 and 4 carbon atoms relative to the weight of the steam cracking effluent considered. Said C2, C3 and C4 olefins can then be advantageously used as polyolefin monomers.

[0216] According to a preferred embodiment of the invention, the method for treating a load comprising a plastic pyrolysis oil comprises, preferably consists of, the sequence of steps, and preferably in the given order:

[0217] - a) hydrogenation, b) hydrotreatment, c) separation and d) separation / washing

[0218] - a) hydrogenation, b) hydrotreatment, c) separation and d) separation / washing and e) fractionation,

[0219] - a) hydrogenation, b) hydrotreatment, c) separation and d) separation / washing, e) fractionation and introduction of the hydrocarbon cut comprising compounds having a boiling point above 175°C in step f) of hydrocracking, the hydrocracked effluent being recycled in step d).

[0220] All embodiments may comprise and preferably consist of more than one aO pretreatment step.

[0221] All embodiments may comprise and preferably consist of more than one steam cracking step g).

[0222] All embodiments comprise recycling at least a portion of a liquid effluent from a separation step c) into step a). Analysis methods used

[0223] The analysis methods and / or standards used to determine the characteristics of the different flows, in particular the load to be treated and the effluents, are known to the person skilled in the art. They are listed below in particular for information purposes. Other methods deemed equivalent may also be used, in particular equivalent IP, EN or ISO methods:

[0224] [Tables 1] Description Methods Density @15°C ASTM D4052 Sulfur Content ISO 20846 Nitrogen Content ASTM D4629 Acid Number ASTM D664 Bromine Number ASTM DI 159 Di-olefin Content from Maleic Anhydride Number MAV Method (1) Oxygenates Content Combustion + Infrared Paraffins Content UOP990-11 Naphthenes and Olefins Content UOP990-11 Aromatics Content UOP990-11 Halogens Content ASTM D7359 Chloride Content ASTM D7536 Metals Content: ASTM D5185 P Fe Si Na B Simulated Distillation ASTM D2887

[0225] (1) MAV method described in the article: C. Lôpez-Garcia et al., Near Infrared Mo- nitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68 LIST OF FIGURES

[0226] The mention of the elements referenced in Figures 1 to 2 allows a better understanding of the invention, without it being limited to the embodiments by particular ones illustrated in Figures 1 to 2. The different embodiments presented can be used alone or in combination with each other, without limitation of combination. [Fig 1]

[0227] [Fig. 1] represents the diagram of a particular embodiment of the method of the present invention, comprising: - a step a) of hydrogenation of a hydrocarbon feedstock resulting from the pyrolysis of plastics 1 in a mixture with at least a portion of the liquid effluent 9a resulting from step c) recycled and in the presence of a hydrogen-rich gas 2 and optionally an amine supplied by the stream 3 and optionally a sulfur compound by the stream 4, carried out in at least one fixed-bed reactor comprising at least one hydrogenation catalyst, to obtain a hydrogenated effluent 5; - a step b) of hydrotreatment of the hydrogenated effluent 5 from step a), in the presence of hydrogen 6 carried out in at least one fixed-bed reactor comprising at least one hydrotreatment catalyst, to obtain a hydrotreated effluent 7; - a step c) of separation of the hydrotreated effluent 7 carried out at high pressure and high temperature (HHPS) to obtain at least a first gaseous effluent 8, and a liquid effluent 9 of which a part 9a is recycled upstream of step a), - a separation step d) carried out at high pressure and low temperature (CHPS) and supplied with the first gaseous effluent 8 and the other part of the liquid effluent 9b from step c) and an aqueous solution 10 and making it possible to obtain at least a second gaseous effluent 11 comprising hydrogen, an aqueous effluent 12 containing dissolved salts, and a hydrocarbon effluent 13; - optionally a step e) of fractionation of the hydrocarbon effluent 13 making it possible to obtain at least a third gaseous effluent 14, a first hydrocarbon cut 15 comprising compounds having a boiling point less than or equal to 175°C (naphtha cut) and a second hydrocarbon cut 16 comprising compounds having a boiling point greater than 175°C (middle distillate cut).

[0228] At the end of step e), a portion of the first hydrocarbon cut 15 comprising compounds having a boiling point less than or equal to 175°C can be sent to a steam cracking process (not shown). Another portion of the first hydrocarbon cut 15 can feed the hydrogenation step a) and / or the hydrotreatment step b) (not shown). [Fig 2]

[0229] [Fig.2] represents the diagram of another particular embodiment of the method of the present invention which is based on the scheme of [Fig.l]. This scheme notably comprises a hydrocracking step f) in which at least part of the second hydrocarbon cut 16 comprising compounds having a boiling point above 175°C from step e) feeds this hydrocracking step f) which is carried out in at least one fixed bed reactor comprising at least one hydrocracking catalyst and is supplied with hydrogen 17. The hydrocracked effluent 18 is recycled upstream of the separation step d).

[0230] Instead of injecting the amine stream 3 at the inlet of hydrogenation step a), it is possible to inject it at the inlet of hydrotreatment step b), at the inlet of separation step c), at the inlet of hydrocracking step f) when it is present, or even not to inject it, depending on the characteristics of the feedstock.

[0231] Only the main steps, with the main flows, are shown in Figures 1 and 2, in order to allow a better understanding of the invention. It is understood that all the equipment necessary for operation is present (balloons, pumps, exchangers, furnaces, columns, etc.), even if not shown. It is also understood that hydrogen-rich gas flows (make-up or recycle), as described above, can be injected at the inlet of each reactor or catalytic bed or between two reactors or two catalytic beds. Means well known to those skilled in the art for purifying and recycling hydrogen can also be implemented. EXAMPLES Example 1 (in accordance with the invention)

[0232] Feedstock 1 treated in the process is a plastic pyrolysis oil (i.e. comprising 100% by weight of said plastic pyrolysis oil) having the characteristics indicated in Table 2.

[0233] Table 2: load characteristics

[0234] [Tables2] Description / Methods Unit Pyrolysis oil Density @15aG ASTM D4052 Terri 0.820 Sulphur content ISO 20846 ppm wt 2500 Nitrogen content ASTM D462& ppm pc ds 730 In-dtce da cri ASTM 0664 isgiOLg LS Bromine content ASTM D1153 80 CeC'eAnes content from India Method MAWi % wt 13 Oxygen content Corr&ashonr-Infra-Red %. weight L0 Paraffin Content UüF%Q-11 % weight 45 UÛP09O-1 Content i % weight 20 O^hes Content UÜP290-11 % weight 25 Aromatrcjues Content UOP990-11 % weight 13 Halogen Content ASTM-D7359 ppm weight 359 ÎFPS313 Content ppm weight 3SG Chloride Content ASTM 07536 ppm weight 32Q Metal Content: ASTM-D5185 P ppm weight 10 Fe ppm weight 25 Si ppm weight 45 Ha ppm weight 2 B ppm weight 2 Simulated DisiiSation: ASTM D2887 0% 2C 40 10% =c 98 30% =c 161 50% =c 232 70% 2C 309 90% 3C 394 100% =0 432

[0235] (1) MAV method described in the article: C. Lôpez-Garcla et al., Near Infrared Mo- nitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68

[0236] Feed 1 and a hydrogen-rich gas 2 are preheated to 100°C in a furnace. A portion of the liquid effluent from separation step c) carried out at 300°C is preheated to 382°C and constitutes a hot liquid recycle 9a. Feed 1, the hydrogen-rich gas and the hot liquid recycle are mixed and subjected to a hydrogenation step a) carried out in a fixed-bed reactor and a NiMo-on-alumina hydrogenation catalyst under the conditions indicated in Table 3.

[0237] For a load flow rate 1 of 6.25 T / h and a hot recycle flow rate of 18.75 T / h, the heat saved thanks to the hot liquid recycle at 382°C, taking into account the superheating from 300 to 382°C, and compared to a liquid recycle cooled to 40°C, is of approximately 3.6 MW. This saved heat reduces the operating costs and the investment costs required for the process. As a result, the products from the process are obtained with a lower carbon footprint, i.e., greenhouse gas emissions, particularly carbon dioxide, are reduced. The heat input from the hot liquid recycle also prevents the feedstock from overheating since it is heated indirectly by mixing. This limits the formation of gums and / or coke at the reactor inlet, which would ultimately lead to an increase in pressure drop.

[0238] Table 3: conditions of step a) of hydrogenation

[0239] [Tables3] Reactor inlet temperature °C 291 Reactor outlet temperature °C 311 Average temperature (WABT) °c 301 Hydrogen partial pressure MPa abs. 6.2 H2 / HC (Hydrogen volume coverage relative to feed volume) NmVm3 700 WH (feed volume flow rate / catalyst volume) h1 0.5 Liquid recycle / feed ratio (liquid recycle mass flow rate from c) to a) / feed mass flow rate to a) m / m 3

[0240] The conditions indicated in Table 3 correspond to cycle start conditions and the average temperature (WABT) is increased by 1°C per month so as to compensate for catalytic deactivation.

[0241] At the end of hydrogenation step a), the conversion rates (= (initial concentration - final concentration) / initial concentration) observed are indicated in table 4.

[0242] Table 4: Conversions of species during step a) of hydrogenation

[0243] [Tables4] Diolefin conversion rate % >70 Olefin conversion rate % >70 Silicon retention % >85

[0244] The hydrogenated effluent 5 from hydrogenation step a) is subjected directly, without separation, to a hydrotreatment step b) carried out in a fixed bed and in the presence of hydrogen 6, and a NiMo-on-alumina type hydrotreatment catalyst under the conditions presented in table 5.

[0245] Table 5: conditions of hydrotreatment step b)

[0246] [Tables5] Average Hydrotreatment Temperature (WABT) °C 303 Hydrogen Partial Pressure MPa abs 6.0 H2 / HC (Hydrogen volume coverage vs. feed volume) Nm3 / m3 700 WH (Feed volume flow rate / catalyst volume) h1 0.5

[0247] The conditions indicated in Table 5 correspond to cycle start conditions and the average temperature (WABT) is increased by 1°C per month in order to compensate for catalytic deactivation.

[0248] The hydrotreated effluent 7 from the hydrotreatment step b) is subjected to a separation step c) at a pressure substantially identical to that of step b) and the temperature of which is controlled at 300°C, making it possible to obtain a gaseous effluent and a liquid effluent, a part of which is heated to 382°C then recycled to the hydrogenation step a), this recycled liquid part constituting a hot recycle 9a.

[0249] The first gaseous effluent from c) 8 and the part of the liquid effluent from c) 9b which is not recycled to step a) are mixed and then subjected to a separation step d): a water stream 10 is injected into the mixture of the gaseous effluent from c) and the part of the liquid effluent 9b from c) which is not recycled to step a); the final mixture reaches a temperature of 40°C in a cold HP drum operating at a pressure substantially identical to that of step c), at the outlet of which a hydrogen-rich gas fraction, an aqueous fraction and the washed liquid effluent are obtained. The hydrogen-rich gas fraction is recycled upstream of the reaction section. The aqueous fraction from the cold HP drum is sent to a stripping column operating at approximately 0.4 MPa abs. to obtain a stripped aqueous fraction and an acid gas fraction. The washed liquid effluent is treated in a stabilization column operating at approximately 0.8 MPa abs.allowing to obtain light gases and a stabilized liquid hydrocarbon effluent 13. The light gas fraction and the acid gases constitute the second gaseous effluent 11. The yields of the different fractions obtained after separation are indicated in table 6 (the yields correspond to the ratios of the mass quantities of the different products obtained in relation to the mass of charge upstream of step a), expressed as a percentage and noted % m / m).

[0250] Table 6: yields of the different products obtained after separation [0251 ] [Tableauxô] Gas fraction 11 (NH3 + H2S + C1-C4) % m / m 0.93 Liquid fraction 13% m / m 99.40

[0252] All or part of the liquid fraction obtained can then be used in a steam cracking step in order to form olefins which can be polymerized in order to form recycled plastics.

[0253] The process implemented according to the invention leads to reduced catalytic deactivations during step a) of hydrogenation and during step b) of hydrotreatment compared to the catalytic deactivations observed according to the prior art.

Claims

Claims

1. A method of treating a feedstock comprising a plastic pyrolysis oil, comprising: a) a hydrogenation step carried out in a hydrogenation reaction section, using at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst, said hydrogenation reaction section being supplied at least by said feedstock mixed with at least a portion of a liquid effluent from a separation step c) and a first gaseous stream comprising hydrogen, said hydrogenation reaction section being carried out at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs.and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrogenated effluent, b) a hydrotreatment step carried out in a hydrotreatment reaction section, using at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreatment catalyst, said hydrotreatment reaction section being fed at least with said hydrogenated effluent from step a) and a second gas stream comprising hydrogen, said hydrotreatment reaction section being carried out at an average temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs.and an hourly volumetric flow rate between 0.1 and 10.0 h1, to obtain a hydrotreated effluent, c) a separation step, fed with the hydrotreated effluent from step b), said step being carried out at a temperature between 200 and 450°C and at a pressure substantially identical to the pressure of step b) to obtain at least a first gaseous effluent, and the liquid effluent, a part of which is recycled upstream of step a), said substantially identical pressure being equal to the pressure of step b) with a pressure difference between 0 and 1 MPa, d) a separation step, fed with the first gaseous effluent and another part of the liquid effluent from step c) and an aqueous solution, said step being carried out at a temperature between 20 and less than 200°C, and at a pressure substantially identical or in-. lower than the pressure of step c), to obtain at least a second gaseous effluent, an aqueous effluent and a hydrocarbon effluent, said substantially identical pressure being equal to the pressure of step c) with a pressure difference of between 0 and 1 MPa, e) optionally a step of fractionation of all or part of the hydrocarbon effluent from step d), to obtain at least a third gaseous effluent and at least a first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C, f) optionally a hydrocracking step carried out in a hydrocracking reaction section, using at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst,said hydrocracking reaction section being fed with at least a portion of said hydrocarbon effluent from step d) and / or with at least a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C from step e) and a third gas stream comprising hydrogen, said hydrocracking reaction section being carried out at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h 1 to obtain a first hydrocracked effluent.,

2. Method according to the preceding claim comprising the fractionation step e).

3. Process according to one of the preceding claims comprising the hydrocracking step f).

4. Method according to one of the preceding claims, wherein in step a) the hydrogen coverage is between 250 and 800 Nm3 of hydrogen per m3 of charge (Nm3 / m3).

5. Process according to one of the preceding claims, in which at least part of the liquid effluent from separation step c) is preheated before being recycled upstream of hydrogenation step a).

6. Method according to one of the preceding claims, in which the weight ratio between the liquid effluent from step c) recycled in step a) and the feed comprising a plastic pyrolysis oil is between 0.01 and 10.

7. Method according to one of the preceding claims, comprising a step aO) of pretreatment of the feedstock comprising a plastic pyrolysis oil, said pretreatment step being carried out upstream of step a) of hydrogenation and comprises a filtration step and / or an electrostatic separation step and / or a step of washing using an aqueous solution and / or an adsorption step.

8. Process according to one of the preceding claims, in which the hydrocarbon effluent from separation step d), or at least one of the two liquid hydrocarbon cuts from step e), is sent in whole or in part to a steam cracking step g) carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C and at a pressure between 0.05 and 0.3 MPa relative.

9. Method according to one of the preceding claims in which the reaction section of step a) uses at least two reactors operating in permutable mode.

10. Method according to one of the preceding claims in which a stream containing an amine and / or a sulfur compound is injected upstream of step a).

11. Process according to one of the preceding claims in which the gaseous effluent from steps c), d) and / or e), and / or the liquid effluent from step c) and / or the hydrocarbon effluent from step d) and / or the first and / or the second hydrocarbon cut from step e) is / are subjected to a heavy metal adsorption step.

12. Process according to one of the preceding claims in which said hydrogenation catalyst comprises a support chosen from alumina, silica, silica-aluminas, magnesia, clays and their mixtures and a hydro-dehydrogenating function comprising either at least one element from group VIII and at least one element from group VIB, or at least one element from group VIII.

13. Process according to one of the preceding claims in which said hydrotreatment catalyst comprises a support chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof, and a hydro-dehydrogenating function comprising at least one element from group VIII and / or at least one element from group VIB.

14. Process according to one of the preceding claims, which further comprises a second hydrocracking step f') carried out in a hydrocracking reaction section, using at least one bed stationary having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of the first hydrocracked effluent from the first hydrocracking step f) and a gas stream comprising hydrogen, said hydrocracking reaction section being operated at a temperature between 250 and 450°C, a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly volumetric flow rate between 0.1 and 10.0 h *, to obtain a second hydrocracked effluent.

15. Process according to one of the preceding claims, in which said hydrocracking catalyst comprises 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 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.

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