Method for treating plastic pyrolysis oil including two-step hydrocracking

Abstract

The present invention relates to a method for treating plastic pyrolysis oil, which comprises: a) selective hydrogenation of the feedstock to obtain a hydrogenation effluent; b) hydrotreatment of the hydrogenation effluent to obtain a hydrotreatment effluent; c) a first hydrocracking step of the hydrotreatment effluent to obtain a first hydrocracking effluent; d) separation of the hydrocracking effluent in the presence of an aqueous stream to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent; e) fractionation of the hydrocarbon-based liquid effluent to obtain at least one gas stream and at least one naphtha fraction and a heavier fraction; f) a second hydrocracking step of the heavier fraction to obtain a second hydrocracking effluent; g) recycling at least a portion of the second hydrocracking effluent to the separation step d).

Description

Technical Field

[0001] The present invention relates to a process for treating plastic pyrolysis oils to obtain a hydrocarbon-based effluent which can be upgraded, for example, by at least partly incorporating it directly into a naphtha pool or a diesel pool or as a feedstock for a steam cracking unit. More particularly, the present invention relates to a process for treating a feedstock obtained from the pyrolysis of plastic waste in order to at least partly remove impurities, in particular olefins (mono-olefins and di-olefins), metals, in particular silicon, and halogens, in particular chlorine, which feedstock may contain relatively large amounts of said impurities, and in order to hydrogenate the feedstock in order to be able to upgrade it.

[0002] The process of the invention thus makes it possible to treat plastic pyrolysis oils to obtain an effluent that can be fully or partially injected into a steam cracking unit. The process of the invention thus makes it possible to upgrade plastic pyrolysis oils while reducing coke formation and thus the risk of plugging and / or premature loss of activity of the catalyst or catalysts used in the steam cracking unit, and reducing the risk of corrosion. Background Art

[0003] The plastics obtained from the collection and sorting channels can undergo a pyrolysis step to obtain, among other things, pyrolysis oils. These plastic pyrolysis oils are usually burned to produce electricity and / or used as fuel in industrial boilers or city heating.

[0004] Another approach to modifying plastic pyrolysis oils is to use these plastic pyrolysis oils as the raw materials of steam cracking units to (re)produce olefins, which are the constituent monomers of certain polymers. However, plastic waste is typically a mixture of several polymers, such as a mixture of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride and polystyrene. In addition, depending on the application, plastics can also contain other compounds, such as plasticizers, pigments, colorants or polymerization catalyst residues, in addition to polymers. Plastic waste may also contain a small amount of biomass, such as from household waste. As a result, the oil obtained by the pyrolysis of plastic waste contains many impurities, particularly dienes, metals, particularly silicon, or halogenated compounds, particularly chlorine-based compounds, heteroelements such as sulfur, oxygen and nitrogen, and insoluble substances, which are generally high in content and incompatible with steam cracking units or units located downstream of steam cracking units, particularly polymerization processes and selective hydrogenation processes. These impurities may cause operability problems, particularly corrosion, coking or catalytic deactivation problems, or incompatibility problems in the application of target polymers. The presence of dienes may also lead to unstable problems in pyrolysis oils, which are characterized by the formation of colloids. Gums and insoluble materials that may be present in the pyrolysis oil can cause plugging problems in the process.

[0005] In addition, during the steam cracking step, the light olefins that petrochemicals seek, especially the yield of ethylene and propylene depends greatly on the quality of the raw materials sent to steam cracking. BMCI (Bureau of Mines Related Index) is generally used to characterize hydrocarbon fractions. In general, when the paraffin content increases and / or when BMCI decreases, the yield of light olefins increases. On the contrary, when BMCI increases, the yield of undesirable heavy compounds and / or coke increases.

[0006] WO 2018 / 055555 proposes a complete process for recycling plastic waste, which is very general and relatively complex, from the various steps of pyrolysis of plastic waste to the steam cracking step. The method of patent application WO 2018 / 055555 comprises in particular a step of hydrotreating the liquid phase obtained directly from the pyrolysis, preferably under very strict conditions, in particular in terms of temperature, for example at 260-300° C., a step of separating the hydrotreated effluent, and then a step of hydrodealkylating the separated heavy effluent, preferably at high temperature, for example at 260-400° C.

[0007] Unpublished patent application FR 20 / 01758 describes a method for treating plastic pyrolysis oil comprising:

[0008] a) selectively hydrogenating the feedstock in the presence of hydrogen and a selective hydrogenation catalyst to obtain a hydrogenation effluent;

[0009] b) hydrotreating the hydrogenated effluent in the presence of hydrogen and a hydrotreating catalyst to obtain a hydrotreated effluent;

[0010] c) separating the hydrotreatment effluent at a temperature of 50 to 370° C. in the presence of an aqueous stream to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent;

[0011] d) optionally, a step of fractionating all or part of the hydrocarbon-based effluent obtained from step c) to obtain a gas stream and at least two hydrocarbon-based streams, which may be a naphtha fraction and a heavy fraction;

[0012] e) a recycling step comprising a stage of recovering a portion of the hydrocarbon-based effluent obtained from the separation step c) or a portion of the hydrocarbon-based stream obtained from the fractionation step d) and / or at least one thereof to the selective hydrogenation step a) and / or the hydrotreatment step b).

[0013] According to patent application FR 20 / 01758, the naphtha fraction obtained from the fractionation step can be sent in whole or in part to a steam cracking unit or to a naphtha pool obtained from conventional petroleum feedstocks, or can be recycled to step e).

[0014] The heavier fraction obtained from the fractionation step can be sent in whole or in part to a steam cracking unit or to a diesel or kerosene pool obtained from conventional petroleum feedstocks, or can be recycled to step e).

[0015] Although the heavier fractions can be sent to a steam cracking unit, few refineries support this option. The reason for this is that the heavier fractions have a high BMCI and contain more naphthenic, naphthenic-aromatic and aromatic compounds relative to the naphtha fraction, thus resulting in a higher C / H ratio. This high ratio is the cause of coking in the steam cracker, so a steam cracking furnace dedicated to this fraction is required.

[0016] Furthermore, steam cracking of this heavy fraction produces smaller amounts of products of interest, in particular ethylene and propylene, but more pyrolysis gasoline.

[0017] Therefore, it is advantageous to convert the heavy fraction at least partially into a naphtha fraction by two-step hydrocracking, thereby minimizing the yield of the heavy fraction and maximizing the yield of the naphtha fraction. This makes it possible to obtain more naphtha, which is preferably sent to steam cracking to produce more olefins, while particularly reducing the risk of blockage during the treatment steps of plastic pyrolysis oil (such as those described in the prior art), and the risk of corrosion encountered during a large amount of coke formation and / or during one or more subsequent steps (such as during the steam cracking step of plastic pyrolysis oil). The heavy fraction not converted in the first hydrocracking step is sent to the second hydrocracking step after separation, and the second hydrocracking step is preferably operated at a medium conversion rate to maximize the selectivity for naphtha fraction compounds (boiling point less than or equal to 175°C, in particular 80-175°C). In addition, the C2-C4 compounds produced during the hydrocracking process can also be sent to steam cracking, which makes it possible to increase the yield of light olefins (ethylene and propylene). Overall, the olefin yield is at least maintained or even increased, while the need for a dedicated steam cracking furnace for the heavy fractions is eliminated. Summary of the invention

[0018] The present invention relates to a method for treating a feedstock containing plastic pyrolysis oil, comprising:

[0019] a) a selective hydrogenation step, in a reaction section fed with at least the feedstock and a gas stream containing hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature of 100-280° C., at a hydrogen partial pressure of 1.0-10.0 MPa absolute pressure and at a temperature of 0.3-10.0 h -1 to obtain a hydrogenation effluent;

[0020] b) a hydroprocessing step, which is carried out in a hydroprocessing reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydroprocessing catalyst, the hydroprocessing reaction section being fed with at least the hydrogenation effluent obtained from step a) and a gas stream comprising hydrogen, the hydroprocessing reaction section being operated at a temperature of 250-430° C., a hydrogen partial pressure of 1.0-10.0 MPa absolute pressure and a temperature of 0.1-10.0 h -1 to obtain a hydroprocessing effluent;

[0021] c) a first hydrocracking step, which is carried out in a hydrocracking reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least said hydrotreated effluent obtained from step b) and a gas stream comprising hydrogen, said hydrocracking reaction section being operated at a temperature of 250-480° C., a hydrogen partial pressure of 1.5-25.0 MPa absolute and a pressure of 0.1-10.0 h -1 to obtain a first hydrocracking effluent;

[0022] d) a separation step fed with the hydrocracking effluent obtained from step c) and an aqueous solution, said step being carried out at a temperature ranging from 50 to 370° C. so as to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent;

[0023] e) a step of fractionating all or part of the hydrocarbon-based effluent obtained from step d) to obtain at least one gas stream and at least two hydrocarbon-based liquid streams, the hydrocarbon-based liquid streams being at least one naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. and a hydrocarbon fraction comprising compounds having a boiling point greater than 175° C.;

[0024] f) a second hydrocracking step, which is carried out in a hydrocracking reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydrocracking catalyst, the hydrocracking reaction section being fed with at least a portion of the hydrocarbon fraction comprising compounds having a boiling point greater than 175° C. obtained in step e) and a gas stream comprising hydrogen, the hydrocracking reaction section being operated at a temperature of 250-480° C., a hydrogen partial pressure of 1.5-25.0 MPa absolute and a pressure of 0.1-10.0 h -1 to obtain a second hydrocracking effluent;

[0025] g) A step of recycling at least a portion of said second hydrocracking effluent obtained from step f) to the separation step d).

[0026] One advantage of the process according to the invention is the purification of at least part of the impurities of the oil obtained from the pyrolysis of plastic waste, which makes it possible to hydrogenate the oil and therefore to upgrade it, in particular by incorporating it directly into the fuel pool, or by making it compatible with treatment in a steam cracking unit, making it possible in particular to obtain light olefins in increased yields, which can be used as monomers in the manufacture of polymers.

[0027] Another advantage of the present invention is the prevention of the risk of clogging and / or corrosion of the treatment unit in which the process of the invention is carried out, which risk is exacerbated by the presence of dienes, metals and halogenated compounds, which are usually present in large amounts in plastic pyrolysis oils.

[0028] The process of the invention thus makes it possible to obtain a hydrocarbon-based effluent obtained from the plastic pyrolysis oil, which is at least partially free of the impurities of the starting plastic pyrolysis oil, thus limiting operability problems, such as corrosion, coking or catalytic deactivation problems, which these impurities may cause, in particular in the steam cracking unit and / or in the units located downstream of the steam cracking unit, in particular the polymerization and selective hydrogenation units. The removal of at least part of the impurities from the oil obtained from the pyrolysis of plastic waste will also make it possible to increase the range of applications of the target polymers, with reduced application incompatibilities.

[0029] The present invention relates to the recovery of plastics, proposing a process for treating the oil obtained from the pyrolysis of plastics to purify it, hydrotreating it and hydrocracking it, in order to obtain a hydrocarbon-based effluent with a reduced impurity content, which effluent is therefore directly upgradeable in the form of a naphtha fraction and / or a diesel fraction, or which has a composition compatible with the feedstock of a steam cracking unit. The hydrocracking makes it possible to convert at least a portion of the heavy fraction (diesel) into compounds of the naphtha fraction, which makes it possible to obtain an improved yield of the naphtha fraction and, when sending this fraction to steam cracking, an improved yield of light olefins, while in particular reducing the risk of blockages during the plastic pyrolysis oil treatment steps (such as those described in the prior art), and the risk of substantial coke formation and / or corrosion encountered during one or more subsequent steps (such as during the steam cracking step of the plastic pyrolysis oil).

[0030] According to one variant, the process also comprises a recycling step h) in which part of the hydrocarbon-based effluent obtained from separation step d) or part of the naphtha fraction having a boiling point less than or equal to 175° C. obtained from fractionation step e) is sent to selective hydrogenation step a) and / or to hydrotreatment step b).

[0031] According to one variant, the amount of the recycle stream coming from step h) is adjusted so that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is less than or equal to 10.

[0032] According to one variant, the method comprises a step a0) of pretreatment of the feedstock comprising plastic pyrolysis oil, said pretreatment step being carried out upstream of the selective hydrogenation step a) and comprising a filtration step and / or a step of washing with water and / or an adsorption step.

[0033] According to one variant, the reaction stage of step a) or b) uses at least two reactors operating in displaceable mode.

[0034] According to one variant, an amine-containing stream is injected upstream of step a).

[0035] According to one variant, the selective hydrogenation catalyst comprises a support chosen from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrogenation-dehydrogenation function comprising at least one element of group VIII and at least one element of group VIB, or at least one element of group VIII.

[0036] According to one variant, the at least one hydrotreatment catalyst comprises a support chosen from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrogenation-dehydrogenation function comprising at least one element of group VIII and / or at least one element of group VIB.

[0037] According to one variant, the hydrocracking catalyst comprises a support chosen from halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites, and a hydrogenation-dehydrogenation function comprising at least one metal of Group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and / or at least one metal of Group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

[0038] According to this variant, the zeolite is chosen from Y zeolite, alone or in combination with other zeolites chosen from Beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 and ZBM-30 zeolites, alone or as a mixture.

[0039] According to one variant, the naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. obtained from step e) is sent in whole or in part to a steam cracking step i) carried out in at least one pyrolysis furnace at a temperature ranging from 700 to 900° C. and a relative pressure ranging from 0.05 to 0.3 MPa.

[0040] According to one variant, the naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. obtained from step e) is fractionated into a heavy naphtha fraction comprising compounds having a boiling point of 80 to 175° C. and a light naphtha fraction comprising compounds having a boiling point less than 80° C., at least part of said heavy fraction being sent to an aromatic complex comprising at least one naphtha reforming step.

[0041] According to this variant, at least part of the light naphtha fraction is sent to the steam cracking step i).

[0042] The invention also relates to products obtainable by the treatment process according to the invention.

[0043] According to the present invention, unless otherwise stated, pressures are absolute pressures, also written as abs., and are given in MPa absolute (or MPaabs.).

[0044] According to the invention, the expressions "included between ... and ... " and "... to ..." are equivalent and mean that the limits of the interval are included in the range of the values ​​stated. If this is not the case, and if the limits are not included in the range, the invention will give such a description.

[0045] For the purposes of the present invention, various ranges of parameters of a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, for the purposes of the present invention, a range of preferred pressure values ​​can be combined with a range of more preferred temperature values.

[0046] Hereinafter, specific and / or preferred embodiments of the present invention may be described. When technically feasible, they may be implemented alone or in combination without limiting the combination.

[0047] In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by DRLide, 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 IUPAC classification.

[0048] The metal content was measured by X-ray fluorescence. DETAILED DESCRIPTION

[0049] raw material

[0050] According to the invention, "plastic pyrolysis oil" is an oil, advantageously in liquid form at room temperature, obtained by pyrolysis of plastics, preferably plastic waste, in particular plastic waste from collection and sorting channels. It contains in particular a mixture of hydrocarbon-based compounds, in particular paraffins, monoolefins and / or diolefins, cycloalkanes and aromatic compounds, these hydrocarbon-based compounds preferably have a boiling point below 700°C and preferably below 550°C. Plastic pyrolysis oil can also contain, and usually does contain impurities, such as metals, in particular silicon and iron, and halogenated compounds, in particular chlorinated compounds. These impurities can be present in high levels in plastic pyrolysis oil, for example up to 350 weight ppm or even 700 weight ppm or even 1000 weight ppm of halogen elements provided by halogenated compounds, up to 100 weight ppm or even 200 weight ppm of metal or semi-metal elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals and metalloids can be compared to pollutants of metallic nature, referred to as metals or metallic elements or semi-metal elements. In particular, metals or metallic elements or semi-metallic elements that may be contained in the oil obtained from the pyrolysis of plastic waste include silicon, iron or both elements. The plastic pyrolysis oil may also contain other impurities, such as heteroelements, in particular provided by sulfur compounds, oxygen compounds and / or nitrogen compounds, in an amount generally less than 10000 ppm by weight of heteroelements, preferably less than 4000 ppm by weight of heteroelements.

[0051] The feedstock for the method according to the invention comprises at least one plastic pyrolysis oil. The feedstock may consist exclusively of one or more plastic pyrolysis oils. Preferably, the feedstock comprises at least 50% by weight, preferably 75-100% by weight, of plastic pyrolysis oil, i.e. preferably 50-100% by weight, preferably 70-100% by weight of plastic pyrolysis oil. The feedstock for the method according to the invention may in particular comprise one or more plastic pyrolysis oils, conventional petroleum-based feedstocks or feedstocks obtained from biomass conversion, which are subsequently co-processed with the plastic pyrolysis oil of the feedstock.

[0052] Plastic pyrolysis oil can be obtained from a thermocatalytic pyrolysis process or can be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

[0053] Pretreatment (optional)

[0054] Said feedstock comprising plastic pyrolysis oil may advantageously be pretreated, before the selective hydrogenation step a), in an optional pretreatment step a0) in order to obtain a pretreated feedstock fed to step a).

[0055] This optional pretreatment step a0) makes it possible to reduce the amount of contaminants that may be present in the feedstock comprising plastic pyrolysis oil, in particular the amount of silicon. Therefore, the optional step a0) of pretreatment of the feedstock comprising plastic pyrolysis oil is advantageously carried out, in particular when the feedstock contains more than 50 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 10 ppm by weight, or even more than 5 ppm by weight of metal elements, and in particular when the feedstock contains more than 20 ppm by weight of silicon, more particularly more than 10 ppm by weight, or even more particularly more than 5 ppm by weight, and even more particularly more than 1.0 ppm by weight of silicon.

[0056] The optional pretreatment step a0) can be carried out by any method known to the person skilled in the art for reducing the amount of pollutants. It may in particular comprise a filtration step and / or a washing step with water and / or an adsorption step.

[0057] According to one variant, the optional pretreatment step a0) is carried out in an adsorption stage operated in the presence of at least one adsorbent. The optional pretreatment step a0) is carried out at a temperature ranging from 0 to 150° C., preferably from 5 to 100° C., and at a pressure ranging from 0.15 to 10.0 MPa absolute, preferably from 0.2 to 1.0 MPa absolute. The adsorption stage is advantageously carried out in at least one adsorption stage having a specific surface area greater than or equal to 100 m 2 / g, preferably greater than or equal to 200m 2 / g of adsorbent, preferably an alumina-type adsorbent. The specific surface area of ​​the at least one adsorbent is advantageously less than or equal to 600m 2 / g, especially less than or equal to 400m 2 The specific surface area of ​​the adsorbent is a surface area measured by the BET method, i.e., a specific surface area determined by nitrogen adsorption according to the standard ASTM D 3663-78 established by the Brunauer-Emmett-Teller method described in the journal The Journal of the American Chemical Society, 60, 309 (1938).

[0058] Advantageously, the adsorbent comprises less than 1% by weight of metallic elements and is preferably free of metallic elements.The term "metallic elements of the adsorbent" is understood to mean elements of groups 6 to 10 of the Periodic Table of the Elements (new IUPAC classification).

[0059] The adsorption section of optional step a0) comprises at least one adsorption tower containing the adsorbent, preferably comprises at least two adsorption towers, preferably two to four adsorption towers. When the adsorption section comprises two adsorption towers, an operating mode can be a mode of operation called "swing" according to the special terminology, in which one tower is online, i.e. in use, and the other tower is on standby. When the adsorbent of the online tower fails, the tower is isolated and the standby tower is online, i.e. in use. The failed adsorbent can then be regenerated in situ and / or replaced with fresh adsorbent so that once the other tower is isolated, the tower containing it can be put online again.

[0060] Another mode of operation is to have at least two towers operating in series. When the adsorbent of the tower located at the top fails, the first tower is isolated, and the failed adsorbent is regenerated in situ or replaced with fresh adsorbent. Then, the tower is put back online in the last position, and so on. This mode of operation is called replaceable mode, or PRS for replaceable reactor systems, or "lead and lag" according to special terms. The combination of at least two adsorption towers makes it possible to overcome the possible and potential rapid poisoning and / or adsorbent blockage due to the combined effects of metal pollutants, dienes, colloids obtained from dienes, and insoluble substances that may be present in the plastic pyrolysis oil to be treated. The reason is that the presence of at least two adsorption towers is conducive to the replacement and / or regeneration of adsorbents, advantageously without stopping the pretreatment unit or even the method, so that the risk of blockage can be reduced, and thus the stop of the unit caused by blockage is avoided to control costs and limit the consumption of adsorbents.

[0061] Said optional pretreatment step a0) may also optionally be fed with at least a portion of a recycle stream advantageously obtained from step h) of the process, either as a mixture with the feedstock comprising plastic pyrolysis oil or separately from the feedstock comprising plastic pyrolysis oil.

[0062] The optional pretreatment step a0) thus makes it possible to obtain a pretreated feedstock which is then fed to the selective hydrogenation step a).

[0063] Selective hydrogenation step a)

[0064] According to the invention, the process comprises a step a) of selective hydrogenation of a feedstock comprising plastic pyrolysis oil, in the presence of hydrogen, under hydrogen pressure and temperature conditions making it possible to keep said feedstock in the liquid phase, and with just the amount of soluble hydrogen necessary for the selective hydrogenation of the dienes present in the plastic pyrolysis oil. Thus, the selective hydrogenation of the dienes in the liquid phase makes it possible to avoid or at least limit the formation of "gums", i.e. polymerization of the dienes and therefore the formation of oligomers and polymers, which can clog the reaction section of the hydrotreatment step b). Said selective hydrogenation step a) makes it possible to obtain a hydrogenation effluent, i.e. an effluent having a reduced olefin content, in particular a diene content, preferably free of dienes.

[0065] According to the present invention, the selective hydrogenation step a) is fed with at least the feedstock comprising plastic pyrolysis oil or the pretreated feedstock obtained from the optional pretreatment step a0), and a feedstock comprising hydrogen (H 2 ). Optionally, the reaction section of step a) may also be fed with at least a portion of a recycle stream, advantageously obtained from step d) or optionally step h), as a mixture with the optionally pretreated feedstock, or separately from the optionally pretreated feedstock, advantageously fed directly at the inlet of at least one reactor of the reaction section of step a). The introduction of at least a portion of the recycle stream into the reaction section of selective hydrogenation step a) advantageously makes it possible to dilute the impurities of the optionally pretreated feedstock and to control the temperature in particular in the reaction section.

[0066] The reaction stage comprises the presence of at least one selective hydrogenation catalyst, advantageously at a temperature of 100-280° C., preferably 120-260° C., preferably 130-250° C., at a hydrogen partial pressure of 1.0-10.0 MPa absolute, preferably 1.5-8.0 MPa absolute and at a temperature of 0.3-10.0 h -1 , preferably 0.5-5.0h -1 The selective hydrogenation at an hourly space velocity (HSV) of 1.5 mol / L is preferably carried out in a fixed bed. The hourly space velocity (HSV) is defined here as the ratio of the hourly volume flow rate of the feedstock containing the plastic pyrolysis oil, which may have been pretreated, to the volume of the one or more catalysts. The hydrogen-containing gas (H) fed to the reaction section of step a) is preferably 2 The amount of the gas stream is advantageously such that the hydrogen coverage is 1-200 Nm 3 Hydrogen / m 3 Raw material (Nm 3 / m 3 ), preferably 1-50Nm 3 Hydrogen / m 3 Raw material (Nm 3 / m 3 ), preferably 5-20Nm3 Hydrogen / m 3 Raw material (Nm 3 / m 3 The hydrogen coverage is defined as the ratio of the volume flow of hydrogen employed under standard temperature and pressure conditions to the volume flow of the "fresh" feedstock (i.e. the feedstock to be treated, which has optionally been pretreated, without taking into account any recycle fraction) at 15°C (in standard m 3 , written as Nm 3 , H 2 / m 3 The hydrogen-containing gas stream fed to the reaction stage of step a) may consist of the hydrogen supply and / or of recycled hydrogen obtained, in particular, from separation step d).

[0067] Advantageously, the reaction section of step a) comprises 1 to 5 reactors. According to a particular embodiment of the invention, the reaction section comprises 2 to 5 reactors, which operate in a replaceable mode, indicated by the term PRS for replaceable reactor systems or by the term "lead and lag". The combination of at least two reactors in PRS mode makes it possible to isolate one reactor, drain the spent catalyst, refill the reactor with fresh catalyst and return the reactor to service without stopping the process. The PRS technology is described in particular in patent FR2681871.

[0068] Advantageously, a reactor insert, for example of the filter plate type, can be used to prevent clogging of one or more reactors. An example of a filter plate is described in patent FR3051375.

[0069] Advantageously, the at least one selective hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrodehydrogenation functionality.

[0070] According to one variant, the hydrodehydrogenation function comprises in particular at least one element of group VIII, preferably chosen from nickel and cobalt, and at least one element of group VIB, preferably chosen from molybdenum and tungsten. According to this variant, the total content of oxides of metal elements of groups VIB and VIII is preferably 1-40% by weight, preferably 5-30% by weight, relative to the total weight of the catalyst. The weight ratio of one or more metals of group VIB to one or more metals of group VIII, expressed as metal oxides, is preferably 1-20, preferably 2-10.

[0071] According to this variant, the reaction section of step a) comprises, for example, a selective hydrogenation catalyst comprising 0.5-12% by weight of nickel, preferably 1-10% by weight of nickel, expressed as nickel oxide NiO relative to the weight of the catalyst, and 10% by weight of molybdenum oxide MoO relative to the weight of the catalyst, on a support, preferably a mineral support, preferably an alumina support. 3It represents 1-30 wt% of molybdenum, preferably 3-20 wt% of molybdenum.

[0072] According to another variant, the hydrodehydrogenation function comprises at least one element of group VIII, preferably nickel, and preferably consists thereof. According to this variant, the content of nickel oxide is preferably 1-50% by weight, preferably 10-30% by weight, relative to the weight of the catalyst. Such a catalyst is preferably used in its reduced form, on a preferably mineral support, preferably on an alumina support.

[0073] The support of the at least one selective hydrogenation catalyst is preferably selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof. The support may contain other dopant compounds, in particular selected from oxides of boron oxide, in particular boron trioxide, zirconium oxide, cerium oxide, titanium oxide, phosphorus pentoxide and mixtures of these oxides. Preferably, the at least one selective hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and optionally doped with boron. When the phosphorus pentoxide P 2 O 5 When present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. 2 O 5 When present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously is at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be, for example, gamma or eta alumina.

[0074] The selective hydrogenation catalyst is, for example, in the form of extrudates.

[0075] Very preferably, in order to hydrogenate the dienes as selectively as possible, step a) may also use, in addition to the above-mentioned selective hydrogenation catalyst, at least one selective hydrogenation catalyst for 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 the catalyst, and molybdenum oxide MoO relative to the weight of the catalyst, on an alumina support. 3 The catalyst preferably contains less than 5 wt. % molybdenum and at least 0.1 wt. % molybdenum, preferably 0.5 wt. % molybdenum. This catalyst containing a small amount of added metal is preferably placed upstream of the above-mentioned selective hydrogenation catalyst.

[0076] Optionally, the feedstock comprising plastic pyrolysis oil, optionally already pretreated, and / or optionally previously mixed with at least a portion of the recycle stream advantageously obtained from step d) or optional step h), can be mixed with a gas stream comprising hydrogen before its introduction into the reaction section.

[0077] The feedstock, which optionally has been pretreated, and / or optionally mixed with at least part of a recycle stream advantageously obtained from step d) or from optional step h), and / or optionally as a mixture with a gaseous stream, may also be heated before introduction into the reaction section of step a), for example by heat exchange, in particular with the hydrotreatment effluent from step b), so as to reach a temperature close to the temperature applied in the reaction section to which it is fed.

[0078] The hydrogenation effluent obtained at the end of step a) has a reduced content of impurities, in particular diolefins, relative to the same impurities, in particular diolefins, contained in the feedstock of the process. The selective hydrogenation step a) generally makes it possible to convert at least 90% and preferably at least 99% of the diolefins contained in the initial feedstock. Step a) may also at least partially remove other contaminants, such as silicon. The hydrogenation effluent obtained at the end of the selective hydrogenation step a) is sent, preferably directly, to the hydrotreatment step b). When at least a portion of the recycle stream obtained by the optional step h) is introduced, the hydrogenation effluent obtained at the end of the selective hydrogenation step a) therefore comprises, in addition to the converted feedstock, one or more fractions of the recycle stream.

[0079] Hydrotreating step b)

[0080] According to the invention, the treatment process comprises a step b) of hydrotreating the hydrogenated effluent obtained from step a), optionally as a mixture with at least a portion of a recycle stream, advantageously obtained from step d) or from optional step h), in the presence of hydrogen and at least one hydrotreating catalyst, advantageously carried out in a fixed bed, so as to obtain a hydrotreated effluent.

[0081] Advantageously, step b) comprises a hydrotreatment reaction known to those skilled in the art, more particularly a hydrogenation reaction of olefins or aromatics, a hydrodemetallization, a hydrodesulfurization, a hydrodenitrogenation, or the like.

[0082] Advantageously, said step b) is carried out in a hydroprocessing reaction section comprising at least one, preferably one to five, fixed bed reactors comprising n catalytic beds, n being an integer greater than or equal to one, preferably one to ten, preferably two to five, said one or more beds each comprising at least one, preferably not more than ten, hydroprocessing catalysts. When the reactor comprises several catalytic beds, i.e. at least two, preferably two to ten, preferably two to five catalytic beds, said catalytic beds are arranged in series in said reactor.

[0083] Said hydrotreatment reaction section is fed with at least said hydrogenation effluent obtained from step a) and a gas stream comprising hydrogen, advantageously into the first catalytic bed of a first functional reactor.

[0084] Said hydrotreatment reaction section of step b) may also be fed with at least a portion of a recycle stream, advantageously obtained from step d) or optionally from step h). Said one or more portions of said recycle stream or the total amount of said recycle stream may be introduced into said hydrotreatment reaction section as a mixture with the hydrogenation effluent obtained from step a) or separately. Said one or more portions of said recycle stream or the total amount of said recycle stream may be introduced into said hydrotreatment reaction section, entering into one or more catalytic beds of said hydrotreatment reaction section of step b). The introduction of at least a portion of said recycle stream advantageously makes it possible to dilute the impurities still present in the hydrogenation effluent and to control the temperature in one or more catalytic beds of the hydrotreatment reaction section involving highly exothermic reactions, in particular to limit the temperature rise.

[0085] Advantageously, the hydrotreatment reaction stage is carried out at a pressure equal to the pressure used in the reaction stage of the selective hydrogenation step a), but at a temperature higher than the temperature of the reaction stage of the selective hydrogenation step a). Thus, the hydrotreatment reaction stage is advantageously carried out at a hydrotreatment temperature of 250-430° C., preferably 280-380° C., at a hydrogen partial pressure of 1.0-10.0 MPa absolute and at a temperature of 0.1-10.0 h -1 , preferably 0.1-5.0h -1 , preferably 0.2-2.0h -1 , preferably 0.2-0.8h -1 The hydrotreatment temperature is carried out at an hourly space velocity (HSV) of 1.5 %. According to the invention, the "hydrotreatment temperature" corresponds to the average temperature in the hydrotreatment reaction section of step b). In particular, it corresponds to the weight average bed temperature (WABT) according to the special terminology, which is well known to those skilled in the art. The hydrotreatment temperature is advantageously determined according to the catalytic system used, the equipment and its configuration. For example, the hydrotreatment temperature (or WABT) is calculated as follows:

[0086] WABT=(T 入口 +2xT 出口 ) / 3

[0087] Where T 入口 : The temperature of the hydrogenated effluent at the inlet of the hydroprocessing reaction section, T 出口 : The temperature of the effluent at the outlet of the hydroprocessing reaction section.

[0088] The hourly space velocity (HSV) is defined herein as the ratio of the hourly volume flow of the hydrogenation effluent obtained from step a) to the volume of the catalyst or catalysts. The hydrogen coverage in step b) is advantageously between 50 and 1000 Nm 3 Hydrogen / m 3 Fresh raw material fed to step a), preferably 50-500 Nm 3 Hydrogen / m3 Fresh raw material fed to step a), preferably 100-300 Nm 3 Hydrogen / m 3 Fresh feedstock fed to step a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen employed under standard temperature and pressure conditions to the volume flow rate of fresh feedstock fed to step a) (i.e. feedstock containing plastic pyrolysis oil or optionally pretreated feedstock fed to step a) (in standard m 3 , denoted as Nm 3 , H 2 / m 3 The hydrogen may consist of the feed and / or recycled hydrogen obtained, in particular, from separation step d).

[0089] Preferably, an additional gas stream containing hydrogen is advantageously introduced into the inlet of each reactor, in particular operated in series, and / or into the inlet of each catalytic bed starting from the second catalytic bed of the hydroprocessing reaction section. These additional gas streams are also referred to as cooling streams. They make it possible to control the temperature in the hydroprocessing reactors, in which the reactions involved are usually highly exothermic.

[0090] Advantageously, the hydroprocessing catalyst used in the step b) can be selected from known hydrodemetallization, hydrotreating or silicon removal catalysts, particularly catalysts for treating petroleum fractions, and combinations thereof. Known hydrodemetallization catalysts are those described, for example, in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US7119045, US 5622616 and US 5089463. Known hydroprocessing catalysts are those described, for example, in patents EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976. Known silicon removal catalysts are those described, for example, in patent applications CN 102051202 and US 2007 / 080099.

[0091] In particular, the hydroprocessing catalyst comprises a carrier, preferably a mineral carrier, and at least one metal element having a hydrodehydrogenation function. The metal element having a hydrodehydrogenation function advantageously comprises at least one Group VIII element, preferably selected from nickel and cobalt, and / or at least one Group VIB element, preferably selected from molybdenum and tungsten. The total content of oxides of Group VIB and Group VIII metal elements is preferably 0.1% to 40% by weight, preferably 5% to 35% by weight, relative to the total weight of the catalyst. The weight ratio of one or more Group VIB metals expressed as metal oxides to one or more Group VIII metals is preferably 1.0 to 20, preferably 2.0 to 10. For example, the hydroprocessing reaction section of step b) of the method comprises a hydroprocessing catalyst, which comprises 0.5% to 10% by weight of nickel, preferably 1% to 8% by weight of nickel, expressed as nickel oxide NiO relative to the total weight of the hydroprocessing catalyst on a mineral carrier, and molybdenum oxide MoO relative to the total weight of the hydroprocessing catalyst. 3 It represents 1.0 wt % to 30 wt % of molybdenum, preferably 3.0 wt % to 29 wt % of molybdenum.

[0092] The support of the hydroprocessing catalyst is advantageously selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof. The support may also contain other dopant compounds, in particular selected from oxides of boron oxide, in particular boron trioxide, zirconium oxide, cerium oxide, titanium oxide, phosphorus pentoxide and mixtures of these oxides. Preferably, the hydroprocessing catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron. When the phosphorus pentoxide P 2 O 5 When present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. 2 O 5 When present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously is at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be, for example, gamma or eta alumina.

[0093] The hydrotreating catalyst is, for example, in the form of extrudates.

[0094] Advantageously, the hydrotreating catalyst used in step b) of the process has a catalyst content greater than or equal to 250 m 2 / g, preferably greater than or equal to 300m 2 The specific surface area of ​​the hydroprocessing catalyst is advantageously less than or equal to 800 m 2 / g, preferably less than or equal to 600m 2 / g, especially less than or equal to 400m2 / g. The specific surface area of ​​the hydroprocessing catalyst is measured by the BET method, i.e. the specific surface area determined by nitrogen adsorption according to the standard ASTM D 3663-78 established by the Brunauer-Emmett-Teller method described in the journal The Journal of the American Chemical Society, 60, 309 (1938). This specific surface area makes it possible to further improve the removal of pollutants, in particular the removal of metals such as silicon.

[0095] According to another aspect of the present invention, the hydroprocessing catalyst as described above also comprises one or more oxygen-containing and / or nitrogen-containing and / or sulfur-containing organic compounds. Such catalysts are usually represented by the term "catalyst with additives". Usually, the organic compound is selected from compounds comprising one or more chemical functional groups selected from carboxyl, alcohol, mercaptan, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide functional groups, or compounds or sugars comprising furan rings.

[0096] The hydrotreatment step b) advantageously allows an optimized treatment of the hydrogenated effluent obtained from step a). It makes it possible in particular to maximize the hydrogenation of the unsaturated bonds of the olefinic compounds present in the hydrogenated effluent obtained from step a), the hydrodemetallization of said hydrogenated effluent and the removal of metals, in particular silicon, still present in the hydrogenated effluent. The hydrotreatment step b) also allows the hydrodenitrogenation (HDN) of the hydrogenated effluent, i.e. the conversion of the nitrogen-containing substances still present in the hydrogenated effluent. Preferably, the nitrogen content of the hydrotreated effluent obtained from step b) is less than or equal to 10 ppm by weight.

[0097] In a preferred embodiment of the invention, the hydrotreatment reaction section comprises several fixed bed reactors, preferably two to five, very preferably two to four fixed bed reactors, each comprising n catalytic beds, n being an integer greater than or equal to one, preferably from one to ten, preferably from two to five, advantageously operated in series and / or in parallel and / or in displaceable (or PRS) mode and / or in "switching" mode. The various optional operating modes, PRS (or lead and lag) mode and switching mode, are well known to those skilled in the art and are advantageously defined hereinafter. The advantage of a hydrotreatment reaction section comprising several reactors is the optimized treatment of the hydrogenation effluent, while making it possible to reduce the risk of clogging of one or more catalytic beds and thus avoid stopping of the plant due to clogging.

[0098] According to a very preferred embodiment of the present invention, the hydroprocessing reaction section comprises the following parts, and preferably consists of the following parts:

[0099] - (b1) two fixed bed reactors operated in switching or displaceable mode, preferably in PRS mode, each of the two reactors preferably having a catalytic bed advantageously comprising a hydrotreating catalyst, preferably selected from known hydrodemetallization or silicon removal catalysts and combinations thereof, and

[0100] -(b2) at least one fixed bed reactor, preferably one reactor, which is located downstream of the two reactors (b1) and advantageously operates in series with the two reactors (b1), the fixed bed reactor (b2) comprising one to five catalytic beds arranged in series and each containing one to ten hydroprocessing catalysts, wherein at least one of the hydroprocessing catalysts advantageously comprises a carrier and at least one metal element, the metal element preferably comprising at least one Group VIII element, preferably selected from nickel and cobalt, and / or at least one Group VIB element, preferably selected from molybdenum and tungsten.

[0101] Optionally, step b) may comprise a heating section located downstream of the hydrotreatment reaction section and wherein the hydrogenated effluent obtained from step a) is heated to a temperature suitable for hydrotreatment, i.e. a temperature ranging from 250 to 430° C., said optional heating section thus comprising one or more exchangers, preferably allowing heat exchange between the hydrogenated effluent and the hydrotreated effluent, and / or a preheating furnace.

[0102] Advantageously, the hydrotreatment step b) allows complete hydrogenation of the olefins present in the initial feedstock and those olefins that may be obtained after the selective hydrogenation step a), and also allows at least partial conversion of other impurities present in the feedstock, such as aromatic compounds, metallic compounds, sulphur compounds, nitrogen compounds, halogen compounds (especially chlorine compounds) and oxygen compounds. Step b) can also further reduce the content of pollutants, such as the content of metals, especially the content of silicon.

[0103] Hydrocracking step c) (first hydrocracking step)

[0104] According to the invention, the treatment process comprises a step c) of subjecting the hydrotreated effluent obtained from step b) to a first hydrocracking, advantageously in a fixed bed, in the presence of hydrogen and at least one hydrocracking catalyst, to obtain a hydrocracking effluent.

[0105] Advantageously, step c) comprises a hydrocracking reaction well known to those skilled in the art and more particularly makes it possible to convert heavy compounds, for example compounds with a boiling point greater than 175° C., into compounds with a boiling point less than or equal to 175° C. contained in the hydrotreatment effluent obtained from step b). Other reactions may then be carried out, for example hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrogenation, etc.

[0106] Advantageously, said step c) is carried out in a hydrocracking reaction section comprising at least one, preferably one to five, fixed bed reactors comprising n catalytic beds, n being an integer greater than or equal to one, preferably one to ten, preferably two to five, said one or more beds each comprising at least one, preferably not more than ten, hydrocracking catalysts. When the reactor comprises several catalytic beds, i.e. at least two, preferably two to ten, preferably two to five catalytic beds, said catalytic beds are arranged in series in said reactor.

[0107] The hydrotreatment step b) and the hydrocracking step c) can advantageously be carried out in the same reactor or in different reactors. When they are carried out in the same reactor, the reactor comprises several catalytic beds, the first catalytic bed comprising one or more hydrotreatment catalysts and the subsequent catalytic beds comprising one or more hydrocracking catalysts.

[0108] Said hydrocracking reaction section is fed with at least said hydrotreatment effluent obtained from step b) and a gas stream comprising hydrogen, advantageously into the first catalytic bed of the first functional reactor.

[0109] Advantageously, the hydrocracking reaction stage is carried out at a pressure equal to the pressure used in the reaction stage of the selective hydrogenation step a) or of the hydrotreatment step b).

[0110] Therefore, the hydrocracking reaction section is advantageously operated at a hydrotreating temperature of 250-480°C, preferably 320-450°C, at a hydrogen partial pressure of 1.5-25.0 MPa absolute, preferably 2-20 MPa absolute, and at a temperature of 0.1-10.0 h -1 , preferably 0.1-5.0h -1 , preferably 0.2-4h -1 The hydrocracking temperature is carried out at an hourly space velocity (HSV) of 1.5 wt %. According to the invention, the "hydrocracking temperature" corresponds to the average temperature in the hydrocracking reaction section of step c) and step f), respectively. In particular, it corresponds to the weight average bed temperature (WABT) according to the special terminology, which is well known to the person skilled in the art. The hydrocracking temperature is advantageously determined according to the catalytic system used, the equipment and its configuration. For example, the hydrocracking temperature (or WABT) is calculated as follows:

[0111] WABT=(T 入口 +2xT 出口 ) / 3

[0112] Where T 入口 : The temperature of the hydrogenated effluent at the inlet of the hydrocracking reaction section, T 出口 : The temperature of the effluent at the outlet of the hydrocracking reaction section.

[0113] The hourly space velocity (HSV) is defined herein as the ratio of the hourly volume flow of the hydrogenation effluent obtained from step a) to the volume of the catalyst or catalysts. The hydrogen coverage in step c) is advantageously between 80 and 2000 Nm 3 Hydrogen / m 3 Fresh raw material fed to step a), preferably 200-1800 Nm 3 Hydrogen / m 3 Fresh feedstock fed to step a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen employed under standard temperature and pressure conditions to the volume flow rate of fresh feedstock fed to step a) (i.e. feedstock containing plastic pyrolysis oil or optionally pretreated feedstock fed to step a) (in standard m 3 , denoted as Nm 3 , H 2 / m 3 The hydrogen may consist of the feed and / or recycled hydrogen obtained, in particular, from separation step d).

[0114] Preferably, an additional gas stream containing hydrogen is advantageously introduced at the inlet of each reactor, in particular operated in series, and / or at the inlet of each catalytic bed starting from the second catalytic bed of the hydrocracking reaction section. These additional gas streams are also referred to as cooling streams. They make it possible to control the temperature in the hydrocracking reactors, in which the reactions involved are generally highly exothermic.

[0115] In an embodiment that makes it possible to maximize the production of a naphtha fraction comprising compounds having a boiling point less than or equal to 175° C., the operating conditions used in the hydrocracking step c) are generally such that a single-pass conversion of greater than 15% by weight and even more preferably ranging from 20% by weight to 95% by weight is obtained, into products having at least 80% by volume of a boiling point less than 175° C., preferably less than 160° C. and preferably less than 150° C.

[0116] Therefore, the hydrocracking step c) may not convert all compounds with a boiling point greater than 175° C. into compounds with a boiling point less than or equal to 175° C. After the fractionation step e), a more or less large part of the compounds with a boiling point greater than 175° C. thus remains, which are sent to the second hydrocracking step f).

[0117] According to the invention, the hydrocracking step c) is carried out in the presence of at least one hydrocracking catalyst.

[0118] The one or more hydrocracking catalysts used in the hydrocracking step c) are conventional hydrocracking catalysts known to those skilled in the art and are of the bifunctional type combining an acid function and a hydrogenation-dehydrogenation function and optionally at least one binder matrix. The acid function consists of a large surface area (generally 150-800 m 2The hydrogenation-dehydrogenation function is provided by at least one metal of Group VIB of the Periodic Table and / or at least one metal of Group VIII.

[0119] Preferably, the one or more hydrocracking catalysts used in step c) comprise a hydrogenation-dehydrogenation functional comprising at least one Group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, preferably selected from cobalt and nickel. Preferably, the one or more catalysts also comprise at least one Group VIB metal selected from chromium, molybdenum and tungsten, alone or as a mixture, and preferably selected from molybdenum and tungsten. Preferably, a hydrogenation-dehydrogenation functional of the NiMo, NiMoW or NiW type.

[0120] Preferably, the content of Group VIII metal in the hydrocracking catalyst(s) is advantageously between 0.5 and 15% by weight, preferably between 1 and 10% by weight, the percentages being expressed as weight percentages of oxide relative to the total weight of the catalyst.

[0121] Preferably, the content of Group VIB metal in the hydrocracking catalyst(s) is advantageously between 5 and 35% by weight, preferably between 10 and 30% by weight, the percentages being expressed as weight percentages of oxide relative to the total weight of the catalyst.

[0122] The one or more hydrocracking catalysts used in step c) may also optionally comprise at least one promoter element deposited on the catalyst, which is selected from phosphorus, boron and silicon, optionally at least one element of Group VIIA (preferably chlorine and fluorine), optionally at least one element of Group VIIB (preferably manganese), and optionally at least one element of Group VB (preferably niobium).

[0123] Preferably, the one or more hydrocracking catalysts used in step c) comprise at least one amorphous or poorly crystalline porous mineral matrix of oxide type chosen from alumina, silica, silica-alumina, aluminates, alumina-boria, magnesia, silica-magnesia, zirconia, titania or clays, alone or as a mixture, and preferably alumina or silica-alumina, alone or as a mixture.

[0124] Preferably, the silica-alumina contains greater than 50 wt% alumina, preferably greater than 60 wt% alumina.

[0125] Preferably, the one or more hydrocracking catalysts used in step c) also optionally comprise a zeolite selected from Y zeolite, preferably USY zeolite, alone or in combination with other zeolites selected from β, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 or ZBM-30 zeolites (alone or as a mixture). Preferably, the zeolite is USY zeolite alone.

[0126] When the catalyst comprises zeolite, the content of zeolite in the one or more hydrocracking catalysts 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.

[0127] Preferred catalysts comprise, and preferably consist of, at least one Group VIB metal and optionally at least one Group VIII non-noble metal, at least one promoter element, preferably phosphorus, at least one Y zeolite and at least one alumina binder.

[0128] Even more preferred catalysts comprise, and preferably consist of, nickel, molybdenum, phosphorus, USY zeolite and optionally beta zeolite and alumina.

[0129] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, alumina and silica-alumina.

[0130] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0131] The hydrocracking catalyst is, for example, in the form of extrudates.

[0132] According to another aspect of the invention, the hydrocracking catalyst as described above also comprises one or more oxygen-containing and / or nitrogen-containing and / or sulfur-containing organic compounds. Such catalysts are usually represented by the term "catalyst with additives". Usually, the organic compound is selected from compounds comprising one or more chemical functional groups selected from carboxyl, alcohol, mercaptan, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide functional groups, or compounds or sugars comprising furan rings.

[0133] The preparation of the catalyst of step a), b) or c) is known and generally comprises the steps of impregnating the metal of group VIII and the metal of group VIB (if present) and optionally phosphorus and / or boron on a support, followed by drying and then optionally calcining. In the case of an additived catalyst, the preparation is generally carried out by simple drying after the introduction of the organic compound without calcining. The term "calcination" in this context refers to a heat treatment at a temperature greater than or equal to 200° C. in a gas comprising air or oxygen. Before the catalyst is used in the process step, the catalyst is generally sulfided to form an active mass. The catalyst of step a) may also be a catalyst used in its reduced form, and therefore a reduction step is involved in its preparation.

[0134] Optionally, step c) may comprise a heating section located downstream of the hydrocracking reaction section and wherein the hydrotreated effluent obtained from step b) is heated to a temperature suitable for hydrocracking, i.e. a temperature ranging from 250 to 480° C. Said optional heating section may thus comprise one or more exchangers, preferably allowing heat exchange between the hydrotreated effluent and the hydrocracking effluent, and / or a preheating furnace.

[0135] Separation step d)

[0136] According to the invention, the treatment process comprises a separation step d), advantageously carried out in at least one washing / separation section, fed with at least the hydrocracking effluent obtained from step c) and an aqueous solution, to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent.

[0137] The gaseous effluent obtained at the end of step d) advantageously comprises hydrogen, preferably at least 90% by volume, preferably at least 95% by volume of hydrogen. Advantageously, said gaseous effluent can be at least partially recycled to the selective hydrogenation step a) and / or to the hydrotreatment step b) and / or to the hydrocracking steps c) and f), this recycling system possibly comprising a purification section.

[0138] The aqueous effluent obtained at the end of step d) advantageously comprises ammonium salts and / or hydrochloric acid.

[0139] The hydrocarbon-based effluent obtained from step d) comprises hydrocarbon-based compounds and advantageously corresponds to the plastic pyrolysis oil of the feedstock, or to the plastic pyrolysis oil and a fraction or biomass of a conventional petroleum-based feedstock co-processed with the pyrolysis oil, wherein at least part of the heavy compounds have been converted into lighter compounds, in order to maximize the naphtha fraction. The hydrocarbon-based effluent is also at least partially freed from its impurities, in particular its olefins (dienes and monoolefins), metals and halogenated impurities.

[0140] This separation step d) makes it possible in particular to remove ammonium chloride salts, which are obtained by the chloride ions released during step b) by hydrogenation of chlorinated compounds, in particular in the form of HCl, with subsequent dissolution in water, and by hydrogenation of nitrogen-containing compounds, in particular in the form of NH 3 The invention also allows the removal of hydrochloric acid formed by the reaction of hydrogen and chloride ions with ammonium ions produced in the form of chlorine and / or provided by injection of amines, subsequently dissolved in water, and thus limits the risk of blockages due to precipitation of ammonium chloride salts, in particular in the transport lines and / or in the stages of the process according to the invention and / or in the transport lines of the steam cracker. It also makes it possible to remove hydrochloric acid formed by the reaction of hydrogen and chloride ions.

[0141] Depending on the content of chlorinated compounds in the initial feed to be treated, a stream containing amines, such as monoethanolamine, diethanolamine and / or monodiethanolamine, may be injected upstream of the selective hydrogenation step a), between the selective hydrogenation step a) and the hydrotreatment step b) and / or between the hydrocracking step c) and the separation step d), preferably upstream of the selective hydrogenation step a), in order to ensure that a sufficient amount of ammonium ions binds to the chloride ions formed during the hydrotreatment step, making it possible to limit the formation of hydrochloric acid and therefore corrosion downstream of the separation stage.

[0142] Advantageously, separation step d) comprises injecting an aqueous solution, preferably water, into the hydrocracking effluent obtained from step c) upstream of the washing / separation stage, so as to at least partially dissolve the ammonium chloride salts and / or the hydrochloric acid and thus improve the removal of chlorinated impurities and reduce the risk of blockages caused by the accumulation of ammonium chloride salts.

[0143] Separation step d) is advantageously carried out at a temperature ranging from 50 to 370° C., preferably from 100 to 340° C., preferably from 200 to 300° C. Separation step d) is advantageously carried out at a pressure close to that used in step a) and / or b) and / or c), preferably from 1.0 to 10.0 MPa, to facilitate the recycling of hydrogen.

[0144] The washing / separation stage of step d) can be carried out at least partly in common or separate washing and separation equipment, which is well known (separation vessels, pumps, heat exchangers, wash columns etc. which can be operated at various pressures and temperatures).

[0145] In an optional embodiment of the present invention, in addition to or separately from the other described embodiments of the present invention, the separation step d) comprises the injection of an aqueous solution into the hydrocracking effluent obtained from step c), followed by a washing / separation section, which advantageously comprises a separation stage for obtaining at least one aqueous effluent loaded with ammonium salts, a washed hydrocarbon-based liquid effluent and a partially washed gaseous effluent. The aqueous effluent loaded with ammonium salts and the washed hydrocarbon-based liquid effluent can then be separated in a decanting vessel to obtain said hydrocarbon-based effluent and said aqueous effluent. Said partially washed gaseous effluent can be introduced in parallel into a washing column, in which it circulates countercurrently with respect to an aqueous stream, said aqueous stream preferably having the same properties as the aqueous solution injected into the hydrocracking effluent, which makes it possible to at least partially, preferably completely, remove the hydrochloric acid contained in the partially washed gaseous effluent and thus obtain said gaseous effluent and an acidic aqueous stream, preferably substantially containing hydrogen. The aqueous effluent obtained from the decanting vessel may optionally be mixed with the acidic aqueous stream and used in a water recirculation loop, optionally as a mixture with the acidic aqueous stream, to feed the separation step d), into the aqueous solution upstream of the washing / separation stage and / or the aqueous stream in the wash column. The water recirculation loop may comprise a supply of water and / or alkaline solution and / or a discharge for removing dissolved salts.

[0146] In another optional embodiment of the present invention, either alone or in combination with the other described embodiments of the present invention, the separation step d) may advantageously comprise a "high pressure" washing / separation section operating at a pressure close to that of the selective hydrogenation step a) and / or the hydrotreatment step b) and / or the hydrocracking step c) in order to facilitate the recycling of hydrogen. This optional "high pressure" section of step d) may comprise a "low pressure" section in order to obtain a hydrocarbon-based liquid fraction free of a portion of the gases dissolved at high pressure and intended to be treated directly in a steam cracking process or optionally sent to a fractionation step e).

[0147] The gas fraction or fractions obtained from separation step d) may be subjected to further purification(s) and separation(s) to recover at least one hydrogen-rich gas (which may be recycled upstream of step a) and / or b) and / or c)) and / or light hydrocarbons (in particular ethane, propane and butanes) which may advantageously be sent alone or as a mixture to the furnace(s) of steam cracking step h) in order to increase the overall yield of olefins.

[0148] The hydrocarbon-based effluent obtained from separation step d) is sent partly or entirely, preferably entirely, to fractionation step e)

[0149] Fractionation step e)

[0150] The process according to the invention comprises a step of fractionating all or part, preferably all, of the hydrocarbon-based effluent obtained from step d) to obtain at least one gaseous stream and at least two hydrocarbon-based liquid streams, the two hydrocarbon-based liquid streams being at least one naphtha fraction comprising compounds having a boiling point less than or equal to 175°C, in particular between 80 and 175°C, and one hydrocarbon fraction comprising compounds having a boiling point greater than 175°C.

[0151] Step e) makes it possible in particular to remove gases dissolved in the hydrocarbon-based liquid effluent, such as ammonia, hydrogen sulphide and light hydrocarbons containing 1 to 4 carbon atoms.

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

[0153] According to one embodiment, step e) can be carried out in a section advantageously comprising at least one stripping tower equipped with a reflux circuit comprising a reflux vessel. The stripping tower is fed with a hydrocarbon-based liquid effluent obtained from step d) and a vapor stream. The hydrocarbon-based liquid effluent obtained from step d) can optionally be heated before entering the stripping tower. Thus, the lightest compounds are entrained at the top of the tower and enter a reflux circuit comprising a reflux vessel, in which a gas / liquid separation is carried out. The gas phase containing light hydrocarbons is taken out of the reflux vessel as a gas stream. A naphtha fraction containing compounds with a boiling point less than or equal to 175° C. is advantageously taken out of the reflux vessel. A hydrocarbon fraction containing compounds with a boiling point greater than 175° C. is advantageously taken out at the bottom of the stripping tower.

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

[0155] The naphtha fraction containing compounds with a boiling point of less than or equal to 175° C. can be sent in whole or in part to a steam cracking unit, at the outlet of which olefins can be (re)formed to participate in the formation of polymers. It can also be sent to a fuel pool, for example a naphtha pool, or it can be sent in part to a recycling step h).

[0156] The hydrocarbon fraction comprising compounds boiling at more than 175° C. is sent, as such, at least partly to a second hydrocracking step f).

[0157] According to a preferred embodiment, the naphtha fraction comprising compounds with a boiling point less than or equal to 175°C is sent in whole or in part to a steam cracking unit, while the fraction comprising compounds with a boiling point greater than 175°C is sent to a hydrocracking step f).

[0158] In another specific embodiment, the optional fractionation step e) makes it possible to obtain, in addition to the gas stream, a naphtha fraction comprising compounds with a boiling point less than or equal to 175° C., preferably between 80 and 175° C., and a kerosene fraction comprising compounds with a boiling point greater than 175° C. and less than 280° C., even a diesel fraction comprising compounds with a boiling point greater than 280° C. and less than 385° C., and a hydrocarbon fraction comprising compounds with a boiling point greater than or equal to 385° C., called a heavy hydrocarbon fraction. The naphtha fraction can be sent in whole or in part to a steam cracking unit and / or to a naphtha pool obtained from conventional petroleum-based feedstocks; it can also be sent to a recycling step h); the kerosene fraction and / or the diesel fraction can also be sent in whole or in part to a steam cracking unit, or to a kerosene or diesel pool, respectively, obtained from conventional petroleum-based feedstocks, or recycled back to the process in the same way as the naphtha fraction; the heavy fraction can be sent at least in part to a second hydrocracking step f).

[0159] In another specific embodiment, the naphtha fraction obtained from step e) comprising compounds with a boiling point less than or equal to 175°C is fractionated into a heavy naphtha fraction comprising compounds with a boiling point of 80-175°C and a light naphtha fraction comprising compounds with a boiling point less than 80°C, and at least a portion of the heavy naphtha fraction is sent to an aromatic complex comprising at least one naphtha reforming step to produce aromatic compounds. According to this embodiment, at least a portion of the light naphtha fraction is sent to the steam cracking step i) described below.

[0160] The gaseous fraction(s) obtained from the fractionation step e) may be subjected to additional purification(s) and separation(s) to recover at least light hydrocarbons, in particular ethane, propane and butanes, which may advantageously be sent alone or as a mixture to one of the furnaces of the steam cracking step i) in order to increase the overall yield of olefins.

[0161] Hydrocracking step f) (Second hydrocracking step)

[0162] According to the invention, the treatment process consists in subjecting at least part of the hydrocarbon fraction comprising compounds having a boiling point greater than 175° C. obtained from step e) to a second hydrocracking step f), advantageously in a fixed bed, in the presence of hydrogen and at least one hydrocracking catalyst, so as to obtain a second hydrocracking effluent.

[0163] Advantageously, step f) comprises a hydrocracking reaction well known to those skilled in the art and more particularly makes it possible to convert at least part of the fraction comprising compounds having a boiling point greater than 175° C. into compounds having a boiling point less than or equal to 175° C. Other reactions may then be carried out, such as hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrogenation, etc.

[0164] Advantageously, said step f) is carried out in a hydrocracking reaction section comprising at least one, preferably one to five, fixed bed reactors comprising n catalytic beds, n being an integer greater than or equal to one, preferably one to ten, preferably two to five, said one or more beds each comprising at least one, preferably not more than ten, hydrocracking catalysts. When the reactor comprises several catalytic beds, i.e. at least two, preferably two to ten, preferably two to five catalytic beds, said catalytic beds are arranged in series in said reactor.

[0165] The hydrocracking reaction stage is fed with at least part of the fraction comprising compounds having a boiling point greater than 175° C. and a gas stream comprising hydrogen, advantageously fed to the first catalytic bed of the first functional reactor.

[0166] Advantageously, said second hydrocracking reaction stage is operated at a pressure equal to the pressure used in the reaction stage of the selective hydrogenation step a) or of the hydrotreatment step b) or of the first hydrocracking step c).

[0167] Therefore, the hydrocracking reaction section is advantageously operated at a hydrotreating temperature of 250-480°C, preferably 320-450°C, at a hydrogen partial pressure of 1.5-25.0 MPa absolute, preferably 3-20 MPa absolute, and at a temperature of 0.1-10.0 h -1 , preferably 0.1-5.0h -1 , preferably 0.2-4h -1 The hourly space velocity (HSV) is defined as the ratio of the hourly volume flow rate of the hydrogenation effluent obtained from step a) to the volume of the one or more catalysts. The hydrogen coverage in step f) is advantageously 80-2000 Nm 3 Hydrogen / m 3 Fresh raw material fed to step a), preferably 200-1800 Nm 3 Hydrogen / m 3 Fresh feedstock fed to step a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen employed under standard temperature and pressure conditions to the volume flow rate of fresh feedstock (i.e. feedstock containing plastic pyrolysis oil) fed to step a) or optionally pretreated feedstock fed to step a) (in standard m 3 , denoted as Nm 3 , H 2 / m 3 The hydrogen may consist of the feed and / or recycled hydrogen obtained, in particular, from separation step d).

[0168] Preferably, an additional gas stream containing hydrogen is advantageously introduced at the inlet of each reactor, in particular operated in series, and / or at the inlet of each catalytic bed starting from the second catalytic bed of the hydrocracking reaction section. These additional gas streams are also referred to as cooling streams. They make it possible to control the temperature in the hydrocracking reactors, in which the reactions involved are generally highly exothermic.

[0169] These operating conditions used in step f) of the process according to the invention generally make it possible to obtain a single-pass conversion greater than 15% by weight and even more preferably between 20% and 80% by weight, converted into a product comprising at least 80% by volume of compounds with a boiling point less than or equal to 175° C., preferably less than 160° C. and preferably less than 150° C. However, the single-pass conversion in step f) is kept moderate in order to maximize the selectivity for naphtha fraction compounds (boiling point less than or equal to 175° C., in particular 80 to less than or equal to 175° C.). The single-pass conversion is limited by using a high recycle ratio in the second hydrocracking step loop. This ratio is defined as the ratio of the flow rate of the feed from step f) to the flow rate of the feed from step a), and this ratio is preferably between 0.2 and 4, preferably between 0.5 and 2.5.

[0170] According to the present invention, the hydrocracking step f) is carried out in the presence of at least one hydrocracking catalyst. Preferably, the hydrocracking catalyst used in the second step is selected from conventional hydrocracking catalysts known to those skilled in the art, such as those described above in the hydrocracking step c). The hydrocracking catalyst used in step f) may be the same as or different from the catalyst used in step c), preferably different.

[0171] In one variant, the hydrocracking catalyst used in step f) comprises a hydrodehydrogenation functionality comprising at least one noble metal of group VIII, chosen from palladium and platinum, alone or as a mixture. The content of noble metal of group VIII is advantageously between 0.01 and 5% by weight, preferably between 0.05 and 3% by weight, the percentages being expressed as percentage by weight of the oxide relative to the total weight of the catalyst.

[0172] Optionally, step f) may comprise a heating section located upstream of the hydrocracking reaction section and wherein said hydrocarbon fraction comprising compounds having a boiling point greater than 175° C. obtained from step e) is heated to a temperature suitable for hydrocracking, i.e. a temperature ranging from 250 to 480° C. Said optional heating section may thus comprise one or more exchangers and / or preheating furnaces.

[0173] Step g) of recycling the second hydrocracking effluent

[0174] According to the invention, the process comprises a step g) of recycling at least part, preferably all, of said second hydrocracking effluent obtained from step f) to separation step d).

[0175] In the recycle of said second hydrocracking effluent obtained from step f) a draw-off may be installed. Depending on the operating conditions of the process, said draw-off may be 0-10 wt.-%, preferably 0.5-5 wt.-% of said hydrocracking effluent obtained from step f) relative to the incoming feedstock.

[0176] Step h) (optional) recycling the hydrocarbon-based effluent obtained from step d) and / or the naphtha fraction having a boiling point of less than or equal to 175° C. obtained from step e)

[0177] The process according to the invention may comprise a recycling step h), in which a portion of the hydrocarbon-based effluent obtained from separation step d) or a portion of the naphtha fraction having a boiling point less than or equal to 175° C. obtained from fractionation step e) is recovered to constitute a recycle stream, which is sent upstream of at least one of the reaction steps of the process according to the invention or directly into at least one of the reaction steps of the process according to the invention, in particular into selective hydrogenation step a) and / or into hydrotreatment step b). Optionally, a portion of the recycle stream may be sent to an optional pretreatment step a0). Preferably, the process according to the invention comprises a recycling step h).

[0178] Preferably, at least part of the hydrocarbon-based effluent obtained from separation step d) or at least part of the naphtha fraction having a boiling point less than or equal to 175° C. obtained from fractionation step e) is fed to hydrotreatment step b).

[0179] Advantageously, the amount of the recycle stream is adjusted so that the weight ratio between the recycle stream and the raw material containing plastic pyrolysis oil, i.e. the raw material to be treated fed to the entire process is less than or equal to 10, preferably less than or equal to 5, 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. Very preferably, the amount of the recycle stream is adjusted so that the weight ratio between the recycle stream and the raw material containing plastic pyrolysis oil is 0.2-5.

[0180] Advantageously, for the initial phase of the process, a hydrocarbon fraction external to the process can be used as recycle stream. A person skilled in the art knows how to choose said hydrocarbon fraction.

[0181] Recycling a portion of the product obtained into or upstream of at least one reaction step of the process according to the invention advantageously makes it possible firstly to dilute the impurities and secondly to control the temperature in one or more reaction steps in which the reactions involved may be highly exothermic.

[0182] According to a preferred embodiment of the present invention, the process for treating a feedstock comprising plastic pyrolysis oil comprises the following sequence of steps, preferably in the given order, and preferably consists of the following sequence of steps: a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling the hydrocracking effluent to step d) to produce an effluent, at least a part of which is suitable for treatment in a steam cracking unit.

[0183] According to another preferred embodiment of the present invention, the process for treating a feedstock comprising plastic pyrolysis oil comprises the following sequence of steps, preferably in the given order, and preferably consists of the following sequence of steps: a0) pretreatment, a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling the hydrocracking effluent to step d) to produce an effluent, at least a portion of which is suitable for treatment in a steam cracking unit.

[0184] According to a third preferred embodiment of the present invention, the method for treating a feedstock comprising plastic pyrolysis oil comprises the following sequence of steps, preferably in the given order, and preferably consists of the following sequence of steps: a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling the hydrocracking effluent to step d), h) recycling a part of the fraction comprising compounds having a boiling point less than or equal to 175°C to step a) and / or b) to produce an effluent, at least a part of which is suitable for treatment in a steam cracking unit.

[0185] According to a fourth preferred embodiment of the present invention, the method for treating a feedstock comprising plastic pyrolysis oil comprises the following sequence of steps, preferably in the given order, and preferably consists of the following sequence of steps: a0) pretreatment, a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling the hydrocracking effluent to step d), h) recycling a portion of the fraction comprising compounds having a boiling point less than or equal to 175°C to step a) and / or b) to produce an effluent, at least a portion of which is suitable for treatment in a steam cracking unit.

[0186] The hydrocarbon-based effluent or the one or more hydrocarbon-based streams thus obtained by treating the plastic pyrolysis oil according to the method of the present invention has a composition compatible with the specifications of the feedstock entering the steam cracking unit. In particular, the composition of the hydrocarbon-based effluent or the one or more hydrocarbon-based streams is preferably such that:

[0187] - the total content of metal elements is less than or equal to 5.0 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, wherein:

[0188] The content of silicon element (Si) is less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.6 ppm by weight, and

[0189] The content of iron (Fe) is less than or equal to 100 ppb by weight,

[0190] - a sulfur content less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight,

[0191] - a nitrogen content less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight, preferably less than or equal to 5 ppm by weight,

[0192] - the asphaltene content is less than 5.0 ppm by weight,

[0193] - the total content of chlorine is less than or equal to 10 ppm by weight, preferably less than 1.0 ppm by weight,

[0194] The content of olefinic compounds (monoolefins and diolefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.1% by weight.

[0195] The contents are given as relative weight concentrations, percentages by weight (%), parts per million by weight (ppm) or parts per billion by weight (ppb), relative to the total weight of the stream under consideration.

[0196] The process according to the invention thus makes it possible to treat plastic pyrolysis oil in order to obtain an effluent that can be injected in whole or in part into a steam cracking unit.

[0197] Steam cracking step i) (optional)

[0198] The naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. obtained from step e) can be sent in whole or in part to the steam cracking step i).

[0199] Advantageously, one or more gas fractions obtained from separation step d) and / or fractionation step e) and containing ethane, propane and butanes may also be sent in whole or in part to steam cracking step i).

[0200] The steam cracking step i) is advantageously carried out in at least one pyrolysis furnace at a temperature of 700-900° C., preferably 750-850° C. and at a relative pressure of 0.05-0.3 MPa. The residence time of the hydrocarbon-based compound is generally less than or equal to 1.0 second (denoted as s), preferably 0.1-0.5 s. Advantageously, steam is introduced upstream of the optional steam cracking step i) and after separation (or fractionation). The amount of water introduced (advantageously in the form of steam) is advantageously 0.3-3.0 kg of water / kg of hydrocarbon-based compounds entering step i). The optional step i) is preferably carried out in parallel in a plurality of pyrolysis furnaces to adapt the operating conditions to the various streams fed to step i), and in particular the streams obtained from step e), and also to manage the pipeline decoking time. The furnace comprises one or more pipelines arranged in parallel. The furnace may also represent a group of furnaces operated in parallel. For example, the furnace may be dedicated to cracking a naphtha fraction containing compounds having a boiling point less than or equal to 175° C.

[0201] The effluent from various steam cracking furnaces is usually recombined to form the effluent before separation. It should be understood that the steam cracking step i) includes a steam cracking furnace, but also includes sub-steps related to steam cracking well known to those skilled in the art. These sub-steps may particularly include heat exchangers, towers and catalytic reactors and recycling to the furnace. The tower generally allows the effluent to be fractionated to recover at least one light fraction comprising hydrogen and compounds containing 2-5 carbon atoms, and a fraction comprising pyrolysis gasoline, and optionally a fraction comprising pyrolysis oil. The tower allows the various components of the light fraction to be separated and fractionated to recover at least one ethylene-rich fraction (C2 fraction) and a propylene-rich fraction (C3 fraction) and an optional butene-rich fraction (C4 fraction). The catalytic reactor particularly allows the selective hydrogenation of C2, C3 or even C4 fractions and pyrolysis gasoline. Saturated compounds, particularly saturated compounds containing 2-4 carbon atoms, are advantageously recycled to the steam cracking furnace to increase the overall yield of olefins.

[0202] This steam cracking step i) makes it possible to obtain at least one effluent comprising olefins containing 2, 3 and / or 4 carbon atoms, i.e. C2, C3 and / or C4 olefins, in a satisfactory content, 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 containing 2, 3 and 4 carbon atoms, relative to the weight of the steam cracking effluent under consideration. Said C2, C3 and C4 olefins can then advantageously be used as polyolefin monomers.

[0203] According to one or more preferred embodiments of the present invention, the method for treating a feedstock comprising plastic pyrolysis oil comprises, alone or in combination, the above sequence of steps, preferably in the order given, and preferably consists of the above sequence of steps, namely: a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling of the second hydrocracking effluent to step d) and steam cracking step i).

[0204] According to a preferred embodiment, the method for treating a feedstock comprising plastic pyrolysis oil comprises the above-mentioned sequence of steps, preferably in the order given, and preferably consists of the above-mentioned sequence of steps, namely a0) pretreatment, a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling the second hydrocracking effluent to step d), g) recycling at least a part of the naphtha fraction comprising compounds having a boiling point of less than or equal to 175° C. to step a) and / or b), and steam cracking step i).

[0205] When the process according to the invention comprises this steam cracking step i), the process therefore makes it possible to obtain olefins from plastic pyrolysis oils, for example plastic waste, in relatively satisfactory yields, which olefins can be used as monomers for the synthesis of new polymers contained in plastics, without clogging or corroding the units.

[0206] Analytical methods used

[0207] Analytical methods and / or standards for determining the properties of various streams, in particular raw materials and effluents to be processed, are known to those skilled in the art. They are listed in particular below:

[0208] Table 1

[0209]

[0210] BRIEF DESCRIPTION OF THE DRAWINGS

[0211] about Figure 1 The information of the elements mentioned in the drawings enables a better understanding of the invention, which is not limited to the specific embodiments illustrated in the drawings. The various embodiments presented can be used alone or in combination with each other without any limitation to the combinations.

[0212] Figure 1 A flow chart showing a specific embodiment of the method of the present invention comprises:

[0213] - a step a) of selective hydrogenation of a hydrocarbon-based feedstock obtained by pyrolysis of plastic 1 in at least one fixed-bed reactor comprising at least one selective hydrogenation catalyst, in the presence of a hydrogen-rich gas 2 and optionally an amine supplied by a stream 3, so as to obtain an effluent 4;

[0214] - a step b) of hydrotreating the effluent 4 obtained from step a) in at least one fixed bed reactor comprising at least one hydrotreating catalyst in the presence of hydrogen 5, so as to obtain a hydrotreated effluent 6;

[0215] - a step c) of subjecting the effluent 6 obtained from step c) to a first hydrocracking in at least one fixed bed reactor comprising at least one hydrocracking catalyst in the presence of hydrogen 7, so as to obtain a first hydrocracking effluent 8;

[0216] - a separation step d) of the effluent 8 carried out in the presence of an aqueous washing solution 9 making it possible to obtain at least one fraction 10 comprising hydrogen, an aqueous fraction 11 containing dissolved salts and a liquid fraction 12 based on hydrocarbons;

[0217] - a step e) of fractionating the hydrocarbon-based liquid fraction 12 so as to obtain at least one gaseous fraction 13, a naphtha fraction 14 comprising compounds having a boiling point less than or equal to 175° C. and a fraction 15 comprising compounds having a boiling point greater than 175° C.;

[0218] - subjecting at least a portion 15a of the fraction comprising compounds having a boiling point greater than 175° C. obtained from step e) to a second hydrocracking step f) in at least one fixed-bed reactor comprising at least one hydrocracking catalyst in the presence of hydrogen 16, so as to obtain a second hydrocracking effluent 17; another portion of the fraction 15 constitutes the discharge 15b;

[0219] - Step of recycling the second hydrocracking effluent 17 to the separation step d).

[0220] Instead of injecting the amine stream 3 into the inlet of the selective hydrogenation step a), it can be injected into the inlet of the hydrotreatment step b), into the inlet of the hydrocracking step c), into the inlet of the separation step d) or not, depending on the characteristics of the feedstock.

[0221] At the end of step e), at least part of the naphtha fraction 14 comprising compounds having a boiling point less than or equal to 175° C. is sent to a steam cracking process (not shown).

[0222] Optionally, part of the naphtha fraction 14 comprising compounds boiling at less than or equal to 175° C. obtained from step e) constitutes a recycle stream fed to the selective hydrogenation step a) (portion 14a) and to the hydrotreatment step b) (portion 14b).

[0223] Figure 1 Only the main steps and main streams are shown to better understand the present invention. It is clearly understood that all the equipment required for functioning (containers, pumps, exchangers, furnaces, towers, etc.) are present, even if they are not shown. It should also be understood that, as described above, the hydrogen-rich gas stream (supply or recycle) can be injected into the inlet of each reactor or catalyst bed, or between two reactors or two catalyst beds. Methods for purifying and recycling hydrogen known to those skilled in the art can also be used.

[0224] Example

[0225] Example 1 (according to the present invention)

[0226] The raw material 1 treated in the method is plastic pyrolysis oil having the characteristics shown in Table 2 (ie comprising 100 wt % of the plastic pyrolysis oil).

[0227] Table 2: Raw material characteristics

[0228]

[0229] (1) The MAV method is described in the article: C.López- et al., Near Infrared Monitoring 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.

[0230] The feedstock 1 undergoes a selective hydrogenation step a) carried out in a fixed bed reactor in the presence of hydrogen 2 and a selective hydrogenation catalyst of the NiMo type on alumina, under the conditions indicated in Table 3.

[0231] Table 3: Conditions for the selective hydrogenation step a)

[0232] temperature ℃ 180 Hydrogen partial pressure MPa absolute pressure 6.4 <![CDATA[H 2 / HC (Hydrogen volume coverage relative to the raw material volume)]]> <![CDATA[Nm 3 / m 3 ]]> 50 HSV (volume flow of feedstock / volume of catalyst) <![CDATA[h -1 ]]> 0.5

[0233] At the end of the selective hydrogenation step a), all the dienes initially present in the feedstock have been converted.

[0234] The effluent 4 obtained from the selective hydrogenation step a) is directly subjected without separation to a hydrotreatment step b) carried out in a fixed bed in the presence of hydrogen 5 and a hydrotreatment catalyst of the NiMo type on alumina, under the conditions indicated in Table 4.

[0235] Table 4: Conditions of hydrotreatment step b)

[0236] Hydrotreating temperature ℃ 355 Hydrogen partial pressure MPa absolute pressure 6.2 <![CDATA[H 2 / HC (Hydrogen volume coverage relative to the raw material volume)]]> <![CDATA[Nm 3 / m 3 ]]> 300 HSV (volume flow of feedstock / volume of catalyst) <![CDATA[h -1 ]]> 0.5

[0237] The effluent 6 obtained from the hydrotreatment step b) is directly subjected without separation to a first hydrocracking step c) carried out in a fixed bed in the presence of hydrogen 7 and a zeolite hydrocracking catalyst comprising NiMo under the conditions shown in Table 5.

[0238] Table 5: Conditions of the first hydrocracking step c)

[0239]

[0240]

[0241] The effluent 8 obtained from the hydrocracking step c) is subjected to a separation step d) according to the invention, in which a water stream is injected into the effluent obtained from the hydrocracking step c); the mixture is then sent to a separation step d) and treated in a tower to wash the acid gases. A gas fraction 10 is obtained at the top of the acid gas washing tower, while at the bottom, a two-phase separation vessel makes it possible to separate the aqueous phase and the liquid phase. The gas washing tower and the two-phase separator operate at high pressure. The liquid phase is then sent to a low-pressure vessel to recover the second gaseous fraction and the liquid effluent that are discharged. The liquid effluent 12 obtained at the end of the separation step d) is sent to a fractionation step e) comprising a stripping tower and a distillation tower to obtain a fraction having a boiling point less than or equal to 175° C. (PI-175° C. fraction) and a fraction having a boiling point greater than 175° C. (175° C.+ fraction).

[0242] The 175° C.+ fraction obtained from the fractionation step e) is sent to a second hydrocracking step f) to increase the conversion of compounds with a boiling point greater than 175° C. A small portion of the 175° C.+ fraction is not sent to the second hydrocracking step f) to avoid accumulation of polycyclic aromatic compounds (which may be coke precursors) (discharge 15b).

[0243] The volume flow of the 175°C+ fraction obtained from fractionation step e) and sent to the second hydrocracking step f) is equal to 80% of the volume flow of the liquid effluent obtained from hydrotreatment step b) and fed to the first hydrocracking step c).

[0244] The second hydrocracking step f) is carried out in a fixed bed in the presence of hydrogen 16 and a zeolite hydrocracking catalyst comprising NiMo under the conditions indicated in Table 6.

[0245] Table 6: Conditions of the second hydrocracking step f)

[0246]

[0247] The effluent 17 obtained from the second hydrocracking step f) is mixed with the effluent 8 from the first hydrocracking step c). The two effluents undergo a separation step d) followed by a fractionation step e), these two steps being common to the two effluents and being carried out as described above.

[0248] Table 7 gives the overall yields of the various fractions obtained at the outlet of hydrocracking steps c) and f) at the end of separation step d) and fractionation step e) (which comprises a stripping column and a distillation column).

[0249] Table 7: Yields of the various products and fractions obtained at the outlet of hydrocracking steps c) and f)

[0250] <![CDATA[H 2 S * ]]> %m / m 0.27 <![CDATA[NH 3 * ]]> %m / m 0.09 C1 %m / m 0.21 C2 %m / m 0.21 C3 %m / m 1.76 C4 %m / m 6.34 PI-175℃ fraction %m / m 93.00 175℃+distillate %m / m 0.50 total %m / m 102.37

[0251] Compound H 2 S and NH 3 It is removed primarily in the form of salts in the aqueous phase removed in separation step d).

[0252] The steps according to the invention, in particular the treatment of the feedstock by hydrocracking steps c) and f), make it possible to obtain very high yields of a naphtha-type PI-175° C. fraction.

[0253] The characteristics of the liquid fractions PI-175°C and 175°C+ obtained after separation step d) and fractionation step e) are listed in Table 8:

[0254] Table 8: Characteristics of PI-175℃ and 175℃+ fractions

[0255]

[0256]

[0257] Both liquid fractions PI-175°C and 175°C+ have compositions compatible with a steam cracking unit because:

[0258] - they do not contain any olefins (mono-olefins and di-olefins);

[0259] - they have a very low chlorine content below the limit required for steam cracking feedstocks (undetectable content and 25 ppb by weight, respectively);

[0260] - the metal content, in particular the iron (Fe) content, is also very low (no metal content detected in the PI-175°C fraction and <1 wt ppm in the 175°C+ fraction; no Fe content detected in the PI-175°C fraction and 50 wt ppb in the 175°C+ fraction), which is below the required limit values ​​for steam cracking feedstocks (metals ≤ 5.0 wt ppm, very preferably ≤ 1 wt ppm; Fe ≤ 100 wt ppb);

[0261] - Finally, they contain sulfur (<2 ppm by weight for the PI-175°C fraction and <2 ppm by weight for the 175°C+ fraction) and nitrogen (<0.5 ppm by weight for the PI-175°C fraction and <3 ppm by weight for the 175°C+ fraction) in contents much lower than the limits required for steam cracking feeds (≤500 ppm by weight, preferably ≤200 ppm by weight for S and N).

[0262] The resulting liquid fraction PI-175°C is then sent to the steam cracking step h) (see Table 9).

[0263] Table 9: Steam cracking step conditions

[0264] Pressure at furnace outlet MPa absolute pressure 0.2 PI-175℃ fraction temperature at furnace outlet ℃ 800 Steam / PI-175℃ fraction ratio kg / kg 0.6 Furnace residence time of PI-175℃ fraction s 0.3

[0265] The effluents from the various steam cracking furnaces were subjected to a separation step which allowed the saturates to be recycled to the steam cracking furnace and resulted in the yields shown in Table 10 (yield = % by mass of product relative to the mass of the PI-175°C fraction upstream of the steam cracking step, expressed as % m / m).

[0266] Table 10: Yields of the steam cracking step

[0267] Fraction PI-175℃ fraction <![CDATA[H 2 ,CO,C1]]> %m / m 7.9 Ethylene %m / m 34.3 Propylene %m / m 18.7 C4 fraction %m / m 14.9 Pyrolysis gasoline %m / m 19.3 Pyrolysis oil %m / m 4.9

[0268] Taking into account the yield of 93% obtained during the pyrolysis oil treatment process for the liquid fraction 175° C.+ at the outlet of the hydrocracking step (see Table 7), it is possible to determine the overall yield of the products obtained from the steam cracking step i) relative to the initial feedstock of the plastic pyrolysis oil type introduced into step a):

[0269] Table 11: Overall process yields of products obtained from the steam cracking step for the PI-175°C fraction

[0270] Fraction PI-175℃ fraction <![CDATA[H 2 ,CO,C1]]> %m / m 7.4 Ethylene %m / m 31.9 Propylene %m / m 17.4 C4 fraction %m / m 13.9 Pyrolysis gasoline %m / m 17.9 Pyrolysis oil %m / m 4.5

[0271] When the PI-175°C fraction is sent to a steam cracking unit, the method according to the invention can achieve total mass yields of ethylene and propylene of 31.9% and 17.4% respectively, relative to the mass of the plastic pyrolysis oil type initial feedstock.

[0272] Furthermore, a specific sequence of steps upstream of the steam cracking step makes it possible to limit the formation of coke and avoid the corrosion problems that would occur if the chlorine was not removed.

[0273] Example 2 (not according to the invention)

[0274] In this example, the feedstock to be treated was the same as described in Example 1 (see Table 2).

[0275] It undergoes selective hydrogenation steps a), b) hydrotreatment and d) separation under the same conditions as described in Example 1. This example is not according to the invention and the effluent obtained from the hydrotreatment step is not subjected to hydrocracking steps c) and f). The liquid effluent obtained at the end of separation step d) constitutes the PI+ fraction.

[0276] The yields of the various products and fractions obtained at the outlet of the hydrotreatment step b) are shown in Table 12 (the yields correspond to the ratio of the mass of the various products obtained to the mass of the upstream feedstock of step a), expressed as a percentage and recorded as % m / m).

[0277] Table 12: Yields of the various products and fractions obtained at the outlet of the hydrotreatment step b)

[0278] <![CDATA[H 2 S]]> %m / m 0.27 <![CDATA[NH 3 ]]> %m / m 0.09 C1 %m / m 0.01 C2 %m / m 0.02 C3 %m / m 0.09 C4 %m / m 0.38 PI+ fraction 99.55 total %m / m 100.05

[0279] The characteristics of the PI+ fraction obtained after separation step d), which corresponds to the liquid effluent, are shown in Table 13:

[0280] Table 13: Characteristics of PI+ fractions

[0281]

[0282]

[0283] The PI+ fraction obtained by the sequence of steps a), b) and d) contains about 35% of naphtha-type compounds with a boiling point less than or equal to 175° C. This low yield of naphtha-type compounds with a boiling point less than or equal to 175° C. is due to the absence of a hydrocracking step in this example not according to the invention.

[0284] The liquid effluent fraction PI+ is sent directly to the steam cracking step i) under the conditions described in Table 14.

[0285] Table 14: Steam cracking step conditions

[0286] Pressure at furnace outlet MPa absolute pressure 0.2 Temperature of PI+ fraction at furnace outlet ℃ 795 Steam / PI+ fraction ratio kg / kg 0.7 Furnace residence time of PI+ fraction s 0.3

[0287] The effluent from the steam cracking furnace is subjected to a separation step which allows the saturates to be recycled to the steam cracking furnace and results in the yields shown in Table 15 (yield = % by mass of product relative to the mass of the PI+ fraction upstream of the steam cracking step, expressed as % m / m).

[0288] Table 15: Yields of the steam cracking step for the PI+ fraction

[0289]

[0290]

[0291] Taking into account the yield of 99.5% obtained during the pyrolysis oil treatment process for the PI+ fraction at the outlet of the hydrotreatment step b) (see Table 12), it is possible to determine the overall yield of the products obtained from the steam cracking step i) relative to the initial feedstock of the plastic pyrolysis oil type introduced into step a):

[0292] Table 16: Overall process yields of products obtained from the steam cracking step for the PI+ fraction

[0293] Fraction PI+ fraction <![CDATA[H 2 ,CO,C1]]> %m / m 8.1 Ethylene %m / m 34.6 Propylene %m / m 18.9 C4 fraction %m / m 15.0 Pyrolysis gasoline %m / m 18.7 Pyrolysis oil %m / m 4.2

[0294] When the liquid fraction PI+ undergoes a steam cracking step, the process according to the invention makes it possible to achieve total mass yields of ethylene and propylene of 34.6% and 18.9% respectively, relative to the mass of the initial feedstock of plastic pyrolysis oil type.

Claims

1. A method for treating a plastic pyrolysis oil feedstock containing chlorinated compounds, the method comprising: a) a selective hydrogenation step, in a reaction section maintained in a liquid phase and fed with at least the feedstock and a gas stream containing hydrogen, at a temperature of 100-280° C., a hydrogen partial pressure of 1.0-10.0 MPa absolute, and a temperature of 0.3-10.0 h in the presence of at least one selective hydrogenation catalyst; -1 The hydrogenation effluent is obtained at an hourly space velocity of 100 to 200 Nm / s, wherein the amount of the hydrogen-containing gas stream fed to the reaction section of step a) is such that the hydrogen coverage is 1-50 Nm / s. 3 Hydrogen / m 3 feedstock to obtain a hydrogenation effluent having a reduced diene content; b) a hydroprocessing step, which is carried out in a hydroprocessing reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydroprocessing catalyst, the hydroprocessing reaction section being fed with at least the hydrogenation effluent obtained from step a) and a gas stream comprising hydrogen, the hydroprocessing reaction section being operated at a temperature of 250-430° C., a hydrogen partial pressure of 1.0-10.0 MPa absolute pressure and a temperature of 0.1-10.0 h -1 to obtain a hydroprocessing effluent; c) a first hydrocracking step, which is carried out in a hydrocracking reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least said hydrotreated effluent obtained from step b) and a gas stream comprising hydrogen, said hydrocracking reaction section being operated at a temperature of 250-480° C., a hydrogen partial pressure of 1.5-25.0 MPa absolute and a temperature of 0.1-10.0 h -1 to obtain a first hydrocracking effluent; d) a separation step fed with the hydrocracking effluent obtained from step c) and an aqueous solution, said separation step being carried out at a temperature ranging from 50 to 370° C. so as to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent, wherein separation step d) comprises injecting the aqueous solution into the hydrocracking effluent obtained from step c) upstream of the washing / separation section; e) a step of fractionating all or part of the hydrocarbon-based effluent obtained from step d) so as to obtain at least one gas stream and at least two hydrocarbon-based liquid streams, the two hydrocarbon-based liquid streams being at least one naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. and one hydrocarbon fraction comprising compounds having a boiling point greater than 175° C.; f) a second hydrocracking step, which is carried out in a hydrocracking reaction section using at least one fixed bed reactor comprising n catalyst beds, n being an integer greater than or equal to 1, each catalyst bed comprising at least one hydrocracking catalyst, the hydrocracking reaction section being fed with at least a portion of the hydrocarbon fraction comprising compounds having a boiling point greater than 175° C. obtained in step e) and a gas stream comprising hydrogen, the hydrocracking reaction section being operated at a temperature of 250-480° C., a hydrogen partial pressure of 1.5-25.0 MPa absolute and a pressure of 0.1-10.0 h -1 to obtain a second hydrocracking effluent; g) A step of recycling at least a portion of said second hydrocracking effluent obtained from step f) to the separation step d).

2. The process according to claim 1 , further comprising a recycling step h) in which a portion of the hydrocarbon-based effluent obtained from the separation step d) or a portion of the naphtha fraction having a boiling point less than or equal to 175° C. obtained from the fractionation step e) is sent to the selective hydrogenation step a) and / or the hydrotreatment step b).

3. The method according to claim 2, wherein the amount of the recycle stream from step h) is adjusted so that the weight ratio between the recycle stream and the plastic pyrolysis oil feedstock is less than or equal to 10.

4. The method according to any one of claims 1 to 3, comprising a step a0) of pretreating the plastic pyrolysis oil raw material, wherein the step a0) is carried out upstream of the selective hydrogenation step a) and comprises a filtering step and / or a washing step with water and / or an adsorption step.

5. The process according to any one of claims 1 to 3, wherein the reaction stage of step a) or b) uses at least two reactors operated in a replaceable mode.

6. The process according to any one of claims 1 to 3, wherein an amine-containing stream is injected upstream of step a).

7. The method according to any one of claims 1 to 3, wherein the selective hydrogenation catalyst comprises a support and a hydrogenation-dehydrogenation functional substance, the support being selected from at least one of alumina, silica, silica-alumina, magnesia, and clay, and the hydrogenation-dehydrogenation functional substance comprising at least one Group VIII element and at least one Group VIB element, or comprising at least one Group VIII element.

8. The method according to any one of claims 1 to 3, wherein the hydroprocessing catalyst comprises a carrier and a hydrogenation-dehydrogenation functional substance, the carrier is selected from at least one of alumina, silica, silica-alumina, magnesia, and clay, and the hydrogenation-dehydrogenation functional substance comprises at least one Group VIII element and / or at least one Group VIB element.

9. The process according to any one of claims 1 to 3, wherein the hydrocracking catalyst of step c) or step f) comprises a support selected from a combination of boron and aluminum oxides, halogenated alumina, amorphous silica-alumina, zeolites and a hydrogenation-dehydrogenation functional comprising at least one Group VIB metal selected from chromium, molybdenum and tungsten, alone or as a mixture, and / or at least one Group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

10. The method according to claim 9, wherein the zeolite is selected from Y zeolite, which is used alone or in combination with other zeolites selected from at least one of beta zeolite, ZSM-12 zeolite, IZM-2 zeolite, ZSM-22 zeolite, ZSM-23 zeolite, SAPO-11 zeolite, ZSM-48 zeolite and ZBM-30 zeolite.

11. The process according to any one of claims 1 to 3, wherein the naphtha fraction comprising compounds having a boiling point less than or equal to 175° C. obtained from step e) is sent in whole or in part to a steam cracking step i) carried out in at least one pyrolysis furnace at a temperature of 700-900° C. and a relative pressure of 0.05-0.3 MPa.

12. The process according to any one of claims 1 to 3, wherein the naphtha fraction comprising compounds having a boiling point of less than or equal to 175°C obtained in step e) is fractionated into a heavy naphtha fraction comprising compounds having a boiling point of 80 to 175°C and a light naphtha fraction comprising compounds having a boiling point of less than 80°C, and at least a part of the heavy naphtha fraction is sent to an aromatic complex comprising at least one naphtha reforming step.

13. The process according to claim 12, wherein at least a portion of the light naphtha fraction is sent to the steam cracking step i).

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