WO2022023263A1

WO2022023263A1 - Method for the treatment of plastic pyrolysis oils including two-stage hydrocracking

Info

Publication number: WO2022023263A1
Application number: PCT/EP2021/070850
Authority: WO
Inventors: Wilfried Weiss; Jérôme Bonnardot; Iñigo RIBAS SANGÜESA
Original assignee: IFP Energies Nouvelles; Repsol S.A.
Priority date: 2020-07-30
Filing date: 2021-07-26
Publication date: 2022-02-03
Also published as: FR3113060A1; US20230287283A1; EP4189038A1; TW202216968A; EP4189038B1; AU2021318798A1; CA3185358A1; JP2023535638A; FR3113060B1; CN116194555A; BR112023001482A2; KR20230044444A

Abstract

The present invention relates to a method for treating a plastic pyrolysis oil, comprising: (a) selectively hydrogenating said feedstock to obtain a hydrogenated effluent; (b) hydrotreating said hydrogenated effluent to obtain a hydrotreated effluent; (c) performing a first hydrocracking step on said hydrotreated effluent to obtain a first hydrocracked effluent; (d) separating the hydrocracked effluent in the presence of an aqueous stream, to obtain a gaseous effluent, a liquid aqueous effluent and a liquid hydrocarbon effluent; (e) fractionating the liquid hydrocarbon effluent to obtain at least one gas stream, at least one naphtha cut and a heavier cut; (f) performing a second hydrocracking step on the heavier cut to obtain a second hydrocracked effluent; (g) recycling at least a portion of said second hydrcracked effluent in said separation step (d).

Description

METHOD FOR TREATMENT OF PLASTICS PYROLYSIS OILS INCLUDING A

TWO-STAGE HYDROCRACKING

TECHNICAL AREA

The present invention relates to a process for treating an oil from the pyrolysis of plastics in order to obtain a hydrocarbon effluent which can be recovered, for example by being at least partly directly integrated into a naphtha or diesel pool or as a feedstock for a unit of steam cracking. More particularly, the present invention relates to a process for treating a charge resulting from the pyrolysis of plastic waste, in order to eliminate at least in part impurities, in particular olefins (mono-, di-olefins), metals, in in particular silicon, and the halogens, in particular chlorine, that said filler may contain in relatively large quantities, and so as to hydrogenate the filler in order to be able to upgrade it.

The process according to the invention therefore makes it possible to treat the pyrolysis oils of plastics to obtain an effluent which can be injected, in whole or in part, into a steam cracking unit. The process according to the invention thus makes it possible to recover the oils from the pyrolysis of plastics, while reducing the formation of coke and thus the risks of clogging and/or premature loss of activity of the catalyst(s) used in the unit of steam cracking, and reducing the risk of corrosion.

PRIOR TECHNIQUE

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

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

In addition, during the steam cracking step, the yields of light olefins sought after for petrochemicals, in particular ethylene and propylene, are highly dependent on the quality of the feeds sent for steam cracking. The BMCI (Bureau of Mines Correlation Index according to Anglo-Saxon terminology) is often used to characterize hydrocarbon cuts. Overall, the yields of light olefins increase when the paraffin content increases and/or when the BMCI decreases. Conversely, the yields of unwanted heavy compounds and/or coke increase when the BMCI increases.

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

Unpublished patent application FR20/01.758 describes a process for treating a plastic pyrolysis oil, comprising: a) the selective hydrogenation of said charge in the presence of hydrogen and a selective hydrogenation catalyst to obtain a hydrogenated effluent; b) hydrotreating said hydrogenated effluent in the presence of hydrogen and a hydrotreating catalyst, to obtain a hydrotreating effluent; c) separation of the hydrotreatment effluent in the presence of an aqueous stream, at a temperature between 50 and 370° C., to obtain a gaseous effluent, an aqueous liquid effluent and a liquid hydrocarbon effluent; d) optionally a step of fractionating all or part of the hydrocarbon effluent from step c), to obtain a gas stream and at least two hydrocarbon streams which may be a naphtha cut and a heavier cut; e) a recycling step comprising a recovery phase of a fraction of the hydrocarbon effluent from step c) of separation or a fraction of and/or at least one of the hydrocarbon stream(s) from ) from step d) of fractionation, to step a) of selective hydrogenation and/or step b) of hydrotreatment.

According to application FR20/01.758, the naphtha cut resulting from the fractionation stage can be sent, in whole or in part, either to a steam cracking unit, or to a naphtha pool resulting from conventional petroleum feedstocks, or be recycled according to the step e).

The heavier cut from the fractionation step can be sent, in whole or in part, either to a steam cracking unit, or to a diesel or kerosene pool from conventional petroleum feedstocks, or be recycled according to step e).

Although the heavier cut can be sent to a steam cracker, few refiners favor this option. Indeed, the heavier cut has a high BMCI and contains more naphthenic, naphtheno-aromatic and aromatic compounds compared to the naphtha cut, leading to a higher C/H ratio. This high ratio is a cause of coking in the steam cracker, thus requiring steam cracking furnaces dedicated to this cut.

In addition, the steam cracking of such a heavy cut produces fewer products of interest, which are in particular ethylene and propylene, but more pyrolysis gasoline.

It would therefore be advantageous to minimize the yield of the heavy cut and to maximize the yield of the naphtha cut by transforming the heavy cut at least in part into a naphtha cut by hydrocracking in two stages. This makes it possible to obtain more naphtha which is preferably sent to steam cracking to produce more olefins while in particular reducing the risks of clogging during plastic pyrolysis oil processing steps, such as those described in the prior art, and the formation of coke in quantities important and/or the risks of corrosion encountered during subsequent step(s), for example during the steam cracking step of plastic pyrolysis oils. The heavy cut which has not been transformed in the first hydrocracking stage is sent, after separation, to a second hydrocracking stage preferably operating at a moderate conversion in order to maximize the selectivity for compounds of the naphtha cut (having a boiling point less than or equal to 175°C, in particular between 80 and 175°C). In addition, the C2 to C4 compounds produced during hydrocracking can also be sent to steam cracking, which makes it possible to improve the yields of light olefins (ethylene and propylene). Overall, the olefin yield is at least maintained, or even improved, while eliminating the need for a dedicated heavy-cut steam cracking furnace.

SUMMARY OF THE INVENTION

The invention relates to a process for treating a charge comprising an oil from the pyrolysis of plastics, comprising: a) a selective hydrogenation step implemented in a reaction section fed at least by said charge and a gas stream comprising hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature between 100 and 280° C., a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric speed between 0.3 and 10.0 h ¹ , to obtain a hydrogenated effluent; b) a hydrotreating step implemented in a hydrotreating reaction section, implementing at least one fixed bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one catalyst hydrotreatment, said hydrotreatment reaction section being fed at least with said hydrogenated effluent from step a) and a gas stream comprising hydrogen, said hydrotreatment reaction section being implemented at a temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric speed between 0.1 and 10.0 h ¹ , to obtain a hydrotreatment effluent; c) a first hydrocracking stage implemented in a hydrocracking reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed at least with said hydrotreated effluent from step b) and a gas stream comprising hydrogen, said hydrocracking reaction section being implemented at a temperature between 250 and 480°C, a hydrogen partial pressure between 1.5 and 25.0 MPa abs. and an hourly volume rate between 0.1 and 10.0 h ¹ , to obtain a first hydrocracked effluent; d) a separation stage, supplied with the hydrocracked effluent from stage c) and an aqueous solution, said stage being carried out at a temperature between 50 and 370° C., to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent; e) a step of fractionating all or part of the hydrocarbon effluent from step d), to obtain at least one gas stream and at least two liquid hydrocarbon streams, said two liquid hydrocarbon streams being at least one naphtha cut comprising compounds having a boiling point less than or equal to 175°C and a hydrocarbon cut comprising compounds having a boiling point greater than 175°C; f) a second hydrocracking step implemented in a hydrocracking reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being supplied with at least a portion of said hydrocarbon cut comprising compounds having a boiling point above 175°C from step e) and a gas stream comprising hydrogen, said hydrocracking reaction section being carried out at a temperature between 250 and 480°C, a hydrogen partial pressure between 1.5 and 25.0 MPa abs. and an hourly volumetric speed between 0.1 and 10.0 h ¹ , to obtain a second hydrocracked effluent; g) a step of recycling at least part of said second hydrocracked effluent from step f) in step d) of separation.

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

Another advantage of the invention is to prevent risks of clogging and/or corrosion of the processing unit in which the method of the invention is implemented, the risks being exacerbated by the presence, often in large quantities , diolefins, metals and halogenated compounds in plastics pyrolysis oil.

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

The present invention participates in the recycling of plastics, by proposing a process for treating an oil resulting from the pyrolysis of plastics in order to purify it, hydrotreat it and hydrocrack it in order to obtain a hydrocarbon effluent with a reduced content of impurities and therefore recoverable, either directly in the form of naphtha cut and/or diesel cut, or having a composition compatible with a load from a steam cracking unit. The fact of hydrocracking makes it possible to transform at least part of the heavy cut (diesel) into compounds of the naphtha cut, which makes it possible to obtain improved yields in the naphtha cut and, when this cut is sent to steam cracking, in light olefins , while in particular reducing the risks of clogging during plastic pyrolysis oil treatment steps, such as those described in the prior art, and the formation of coke in large quantities and/or the risks of corrosion encountered during subsequent step(s), for example during the steam cracking step of the plastic pyrolysis oils.

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

According to a variant, the quantity of the recycle stream of step h) is adjusted so that the weight ratio between the recycle stream and the charge comprising a plastics pyrolysis oil is less than or equal to 10.

According to a variant, the method comprises a step aO) of pretreatment of the feed comprising an oil from the pyrolysis of plastics, said pretreatment step being implemented upstream of step a) of selective hydrogenation and comprises a step of filtration and/or a step of washing with water and/or an adsorption step. According to a variant, the reaction section of step a) or b) implements at least two reactors operating in switchable mode.

Alternatively, a stream containing an amine is injected upstream of step a).

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

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

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

According to this variant, said zeolite is chosen from Y zeolites, alone or in combination, with other zeolites from beta zeolites, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM- 48, ZBM-30, singly or in combination. According to a variant, the naphtha cut comprising compounds having a boiling point less than or equal to 175° C. resulting from stage e), all or in part, is sent to a stage i) of steam cracking carried out in at least one furnace pyrolysis at a temperature between 700 and 900° C. and at a pressure between 0.05 and 0.3 relative MPa. According to a variant, Ja naphtha cut comprising compounds having a boiling point less than or equal to 175° C. resulting from stage e) is fractionated into a heavy naphtha cut comprising compounds having a boiling point between 80 and 175 °C and a light naphtha cut comprising compounds having a boiling point below 80°C, at least part of said heavy cut being sent to an aromatic complex comprising at least one naphtha reforming step.

According to this variant, at least part of the light naphtha cut is sent to stage i) of steam cracking.

The invention also relates to the product capable of being obtained by the treatment process according to the invention. According to the present invention, the pressures are absolute pressures, also denoted abs., and are given in absolute MPa (or MPa abs.), unless otherwise indicated.

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

Within the meaning of the present invention, the various parameter ranges for a given step such as the pressure ranges and the temperature ranges can be used alone or in combination. For example, within the meaning of the present invention, a range of preferred pressure values can be combined with a range of more preferred temperature values.

In the following, particular and/or preferred embodiments of the invention can be described. They may be implemented separately or combined with each other, without limitation of combination when technically feasible. In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, ^81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

The metal content is measured by X-ray fluorescence.

DETAILED DESCRIPTION The load

According to the invention, a “plastic pyrolysis oil” is an oil, advantageously in liquid form at ambient temperature, resulting from the pyrolysis of plastics, preferably plastic waste originating in particular from collection and sorting channels. It comprises in particular a mixture of hydrocarbon compounds, in particular paraffins, mono- and/or di-olefins, naphthenes and aromatics, these hydrocarbon compounds preferably having a boiling point below 700° C. and preferably below 550°C. Plastics pyrolysis oil can and most often does include impurities such as metals, including silicon and iron, halogenated compounds, including chlorine compounds. These impurities may be present in the plastic pyrolysis oils at high levels, for example up to 350 ppm by weight or even 700 ppm by weight or even 1000 ppm by weight of halogen elements provided by halogenated compounds, up to 100 ppm weight, even 200 ppm weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, poor metals and metalloids can be assimilated to contaminants of a metallic nature, called metals or metallic or semi-metallic elements. In particular, the metals or metallic or semi-metallic elements, possibly contained in the oils resulting from the pyrolysis of plastic waste, comprise silicon, iron or these two elements. The plastic pyrolysis oil may also include other impurities such as heteroelements provided in particular by sulfur compounds, oxygenated compounds and/or nitrogen compounds, at levels generally below 10,000 ppm by weight of heteroelements and preferably below at 4000 ppm weight of heteroelements.

The charge of the process according to the invention comprises at least one plastic pyrolysis oil. Said charge may consist solely of pyrolysis oil(s) of plastics. Preferably, said filler comprises at least 50% by weight, preferably between 75 and 100% by weight, of plastic pyrolysis oil, that is to say preferably between 50 and 100% by weight, preferably between 70% and 100% weight of plastic pyrolysis oil. The feedstock of the process according to the invention may comprise, among other things, one or more plastic pyrolysis oil(s), a conventional petroleum feedstock or a feedstock resulting from the conversion of biomass which is then co-treated with the oil of pyrolysis of plastics from the charge.

Plastic pyrolysis oil can come from a thermal or catalytic pyrolysis treatment or even be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

Pretreatment (optional)

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

This optional pretreatment step aO) makes it possible to reduce the quantity of contaminants, in particular the quantity of silicon, possibly present in the charge comprising a plastic pyrolysis oil. Thus, an optional step aO) of pretreating the charge comprising a plastic pyrolysis oil is advantageously carried out in particular when said charge comprises 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 metallic elements, and in particular when said filler comprises more than 20 ppm by weight of silicon, more particularly more than 10 ppm by weight, even more than 5 ppm by weight and even more particularly more than 1.0 ppm by weight of silicon.

Said optional pretreatment step aO) can be implemented by any method known to those skilled in the art which makes it possible to reduce the quantity of contaminants. It may in particular comprise a filtration step and/or a step of washing with water and/or an adsorption step.

According to a variant, said optional pretreatment step aO) is implemented in an adsorption section operated in the presence of at least one adsorbent. Said optional pretreatment step aO) is implemented at a temperature between 0 and 150°C, preferably between 5 and 100°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 1.0 MPa abs. The adsorption section is advantageously carried out in the presence of at least one adsorbent, preferably of the alumina type, having a specific surface area greater than or equal to 100 m ² /g, preferably greater than or equal to 200 m ² /g. The specific surface of said at least one adsorbent is advantageously less than or equal to 600 m ² /g, in particular less than or equal to 400 m ² /g. The specific surface of the adsorbent is a surface measured by the BET method, i.e. the specific surface determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT method. -TELLER described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938).

Advantageously, said adsorbent comprises less than 1% by weight of metallic elements, preferably is free of metallic elements. By metallic elements of the adsorbent, we mean the elements of groups 6 to 10 of the periodic table of elements (new IUPAC classification).

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

Another mode of operation is to have at least two columns operating in series. When the absorbent of the column placed at the head is used up, this first column is isolated and the used absorbent is either regenerated in situ or replaced by fresh absorbent. The column is then brought back in line in the last position and so on. This operation is called permutable mode, or according to the English term "PRS" for Permutable Reactor System or even "lead and lag" according to the Anglo-Saxon term. The association of at least two adsorption columns makes it possible to overcome poisoning and/or possible and possibly rapid clogging of the adsorbent under the joint action of metallic contaminants, diolefins, gums from diolefins and insoluble possibly present in the pyrolysis oil of plastics to be treated. The presence of at least two adsorption columns in fact facilitates the replacement and/or regeneration of the adsorbent, advantageously without stopping the pretreatment unit, or even the process, thus making it possible to reduce the risks of clogging and therefore avoid unit shutdown due to clogging, control costs and limit adsorbent consumption.

Said optional pretreatment step aO) can also optionally be supplied with at least a fraction of a recycle stream, advantageously from step h) of the process, mixed or separately from the feed comprising a plastic pyrolysis oil.

Said optional pretreatment step aO) thus makes it possible to obtain a pretreated feed which then feeds step a) of selective hydrogenation.

Stage a) of selective hydrogenation

According to the invention, the method comprises a step a) of selective hydrogenation of the charge comprising an oil from the pyrolysis of plastics carried out in the presence of hydrogen, under conditions of hydrogen pressure and temperature making it possible to maintain said charge in phase liquid and with a quantity of soluble hydrogen just necessary for selective hydrogenation of the diolefins present in the plastic pyrolysis oil. The selective hydrogenation of diolefins in the liquid phase thus makes it possible to avoid or at least limit the formation of "gums", that is to say the polymerization of diolefins and therefore the formation of oligomers and polymers, which can clog the reaction section of step b) hydrotreatment. Said stage a) of selective hydrogenation makes it possible to obtain a hydrogenated effluent, that is to say an effluent with a reduced content of olefins, in particular of diolefins, preferably free of diolefins.

According to the invention, said stage a) of selective hydrogenation is implemented in a reaction section fed at least by said charge comprising an oil from the pyrolysis of plastics, or by the pretreated charge resulting from the optional stage aO) of pretreatment , and a gas stream comprising hydrogen (H ₂ ). Optionally, the reaction section of said step a) can also be additionally supplied with at least a fraction of a recycle stream, advantageously from step d) or from optional step h), either mixed with said charge, optionally pretreated, or separately from the charge, optionally pretreated, advantageously directly at the inlet of at least one of the reactors of the reaction section of step a). The introduction of at least a fraction of said recycle stream into the reaction section of stage a) of selective hydrogenation advantageously makes it possible to dilute the impurities of the charge, optionally pretreated, and to control the temperature in particular in said reaction section .

Said reaction section implements selective hydrogenation, preferably in a fixed bed, in the presence of at least one selective hydrogenation catalyst, advantageously at a temperature between 100 and 280° C., preferably between 120 and 260° C., of preferably between 130 and 250°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs, preferably between 1.5 and 8.0 MPa abs and at an hourly volume rate (WH) between 0 .3 and 10.0 h ¹ , preferably between 0.5 and 5.0 h ¹ . The hourly volumetric speed (WH) is defined here as the ratio between the hourly volumetric flow rate of the charge comprising the plastics pyrolysis oil, optionally pretreated, by the volume of catalyst(s). The quantity of the gas stream comprising hydrogen (H2), supplying said reaction section of step a), is advantageously such that the hydrogen coverage is between 1 and 200 Nm ³ of hydrogen per m ³ of charge ( Nm ³ /m ³ ), preferably between 1 and 50 Nm ³ of hydrogen per m ³ of charge (Nm ³ /m ³ ), preferably between 5 and 20 Nm ³ of hydrogen per m ³ of charge (Nm ³ /m ³ ). The hydrogen coverage is defined as the ratio of the volume flow rate of hydrogen taken under normal conditions of temperature and pressure compared to the volume flow rate of "fresh" load, that is to say the load to be treated, possibly pretreated , without taking into account any recycled fraction, at 15° C. (in normal m ³ , denoted Nm ³ , of H2 per m ³ of charge). The gas stream comprising hydrogen, which feeds the reaction section of stage a), may consist of a make-up of hydrogen and/or recycled hydrogen originating in particular from stage d) of separation.

Advantageously, the reaction section of said step a) comprises between 1 and 5 reactors. According to a particular embodiment of the invention, the reaction section comprises between 2 and 5 reactors, which operate in permutable mode, called according to the English term “PRS” for Permutable Reactor System or even “lead and lag”. The association of at least two reactors in PRS mode makes it possible to isolate a reactor, to unload the spent catalyst, to reload the reactor with fresh catalyst and to put said reactor back into service without stopping the process. The PRS technology is described, in particular, in patent FR2681871. Advantageously, reactor internals, for example of the filter plate type, can be used to prevent clogging of the reactor(s). An example of a filter plate is described in patent FR3051375.

Advantageously, said at least selective hydrogenation catalyst comprises a support, preferably mineral, and a hydro-dehydrogenating function.

According to a variant, the hydro-dehydrogenating function comprises in particular at least one element from group VIII, preferably chosen from nickel and cobalt, and at least one element from group VI B, preferably chosen from molybdenum and tungsten. According to this variant, the total content of oxides of the metal elements of groups VI B and VIII is preferably between 1% and 40% by weight, preferably from 5% to 30% by weight relative to the total weight of the catalyst. The weight ratio expressed as metal oxide between the metal (or metals) of group VI B relative to the metal (or metals) of group VIII is preferably between 1 and 20, and preferably between 2 and 10.

According to this variant, the reaction section of said step a) comprises for example a selective hydrogenation catalyst comprising between 0.5% and 12% by weight of nickel, preferably between 1% and 10% by weight of nickel (expressed as nickel oxide NiO relative to the weight of said catalyst), and between 1% and 30% by weight of molybdenum, preferably between 3% and 20% by weight of molybdenum (expressed as molybdenum oxide MOO3 relative to the weight of said catalyst) on a preferably mineral support, preferably on an alumina support.

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

The support for said at least one selective hydrogenation catalyst is preferably chosen from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof. Said support may contain doping compounds, in particular oxides chosen from boron oxide, in particular boron trioxide, zirconia, ceria, titanium oxide, phosphoric anhydride and a mixture of these oxides. Preferably, said at least selective hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and optionally boron. When phosphoric anhydride P2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. When boron trioxide B2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may for example be a y (gamma) or h (eta) alumina.

Said selective hydrogenation catalyst is for example in the form of extrudates.

Very preferably, in order to hydrogenate the diolefins as selectively as possible, step a) can implement, in addition to the selective hydrogenation catalysts described above, in addition at least one selective hydrogenation catalyst used in the process. step a) comprising less than 1% by weight of nickel and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, expressed as nickel oxide NiO relative to the weight of said catalyst, and less than 5% by weight of molybdenum and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, expressed as molybdenum oxide MOO3 relative to the weight of said catalyst, on an alumina support. This catalyst with a low metal content is preferably placed upstream of the selective hydrogenation catalysts described above.

Optionally, the charge which comprises a plastics pyrolysis oil, optionally pretreated, and/or optionally mixed beforehand with at least a fraction of a recycle stream, advantageously from stage d) or from optional stage h) , can be mixed with the gas stream comprising hydrogen prior to its introduction into the reaction section.

Said charge, optionally pretreated, and/or optionally mixed with at least a fraction of the recycle stream, advantageously from step d) or optional step h), and/or optionally mixed with the gas stream, can also be heated before its introduction into the reaction section of step a), for example by heat exchange in particular with the hydrotreatment effluent from step b), to reach a temperature close to the temperature used in the reaction section which it feeds. The content of impurities, in particular of diolefins, of the hydrogenated effluent obtained at the end of stage a) is reduced compared to that of the same impurities, in particular of diolefins, included in the charge of the process. Stage a) of selective hydrogenation generally makes it possible to convert at least 90% and preferably at least 99% of the diolefins contained in the initial charge. Step a) also allows the elimination, at least in part, of other contaminants, such as for example silicon. The hydrogenated effluent obtained at the end of stage a) of selective hydrogenation is sent, preferably directly, to stage b) of hydrotreatment. When at least a fraction of the recycle stream resulting from optional step h) is introduced, the hydrogenated effluent obtained at the end of step a) of selective hydrogenation therefore comprises, in addition to the converted feed, said fraction(s) of the recycle stream.

Stage b) of hydrotreatment

According to the invention, the treatment process comprises a step b) of hydrotreatment, advantageously in a fixed bed, of said hydrogenated effluent from step a), optionally in a mixture with at least a fraction of a recycle stream, advantageously from stage d) or from optional stage h), in the presence of hydrogen and of at least one hydrotreatment catalyst, to obtain a hydrotreatment effluent.

Advantageously, step b) implements hydrotreatment reactions well known to those skilled in the art, and more particularly hydrogenation reactions of olefins, aromatics, hydrodemetallization, hydrodesulphurization, hydrodenitrogenation, etc

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

Said hydrotreating reaction section is supplied at least with said hydrogenated effluent from step a) and a gas stream comprising hydrogen, advantageously at the level of the first catalytic bed of the first reactor in operation.

Said hydrotreating reaction section of stage b) can also be supplied with at least a fraction of the recycle stream, advantageously from stage d) or from optional stage h). Said fraction(s) of said recycle stream or all of the recycle stream can be introduced into said hydrotreating reaction section mixed with the hydrogenated effluent from the step a) or separately. Said fraction(s) of said recycle stream or all of the recycle stream can be introduced into said hydrotreating reaction section at the level of one or more catalytic beds of said hydrotreating reaction section of step b). The introduction of at least a fraction of said recycle stream advantageously makes it possible to dilute the impurities still present in the hydrogenated effluent and to control the temperature, in particular to limit the temperature increase, in the bed(s) catalyst(s) of the hydrotreating reaction section which implements highly exothermic reactions.

Advantageously, said hydrotreating reaction section is implemented at a pressure equivalent to that used in the reaction section of stage a) of selective hydrogenation, but at a higher temperature than that of the reaction section of stage a) selective hydrogenation. Thus, said hydrotreating reaction section is advantageously carried out at a hydrotreating temperature between 250 and 430°C, preferably between 280 and 380°C, at a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and at an hourly volume rate (WH) between 0.1 and 10.0 h ¹ , preferably between 0.1 and 5.0 h ¹ , preferably between 0.2 and 2.0 h ¹ , preferably between 0 .2 and 0.8 h ¹ . According to the invention, the “hydrotreatment temperature” corresponds to an average temperature in the hydrotreatment reaction section of step b). In particular, it corresponds to the Weight Average Bed Temperature (WABT) according to the established Anglo-Saxon term, well known to those skilled in the art. The hydrotreatment temperature is advantageously determined as a function of the catalytic systems, of the equipment, of the configuration thereof, used. For example, the hydrotreating temperature (or WABT) is calculated as follows:

WABT - (Xeos + 2x Issdis)/3 with T _inlet : the temperature of the hydrogenated effluent at the inlet of the hydrotreatment reaction section, T _SO rtie: the temperature of the effluent at the outlet of the hydrotreatment reaction section.

The hourly volumetric speed (WH) is defined here as the ratio between the hourly volumetric flow rate of the hydrogenated effluent from stage a) per volume of catalyst(s). The hydrogen coverage in stage b) is advantageously between 50 and 1000 Nm ³ of hydrogen per m ³ of fresh charge which supplies stage a), and preferably between 50 and 500 Nm ³ of hydrogen per m ³ of fresh feed which feeds stage a), preferably between 100 and 300 Nm ³ of hydrogen per m ³ of fresh feed which feeds stage a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen taken under normal conditions of temperature and pressure compared to the volume flow rate of fresh charge which supplies stage a), that is to say of charge comprising a plastics pyrolysis oil, or by the optionally pretreated charge, which feeds stage a) (in normal m ³ , denoted Nm ³ , of H2 per m ³ of fresh charge). The hydrogen can consist of a make-up and/or of recycled hydrogen resulting in particular from stage d) of separation.

Preferably, an additional gas stream comprising hydrogen is advantageously introduced at the inlet of each reactor, in particular operating in series, and/or at the inlet of each catalytic bed from the second catalytic bed of the hydrotreating reaction section. These additional gas streams are also called cooling streams. They make it possible to control the temperature in the hydrotreating reactor in which the reactions implemented are generally very exothermic.

Advantageously, said hydrotreating catalyst used in said step b) can be chosen from known catalysts for hydrodemetallization, hydrotreating, silicon capture, used in particular for the treatment of petroleum cuts, and combinations thereof. Known hydrodemetallization catalysts are for example those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known hydrotreating catalysts are for example those described in patents EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976. Known silicon capture catalysts are for example those described in patent applications CN 102051202 and US 2007/080099. In particular, said hydrotreating catalyst comprises a support, preferably mineral, and at least one metallic element having a hydro-dehydrogenating function. Said metallic element having a hydro-dehydrogenating function advantageously comprises at least one element from group VIII, preferably chosen from the group consisting of nickel and cobalt, and/or at least one element from group VI B, preferably chosen from the group group consisting of molybdenum and tungsten. The total content of oxides of the metal elements of groups VIB and VIII is preferably between 0.1% and 40% by weight, preferably from 5% to 35% by weight, relative to the total weight of the catalyst. The weight ratio expressed as metal oxide between the metal (or metals) of group VIB relative to the metal (or metals) of group VIII is preferably between 1.0 and 20, preferably between 2.0 and 10 For example, the hydrotreating reaction section of step b) of the process comprises a hydrotreating catalyst comprising between 0.5% and 10% by weight of nickel, preferably between 1% and 8% by weight of nickel. , expressed as nickel oxide NiO relative to the total weight of the hydrotreating catalyst, and between 1.0% and 30% by weight of molybdenum, preferably between 3.0% and 29% by weight of molybdenum, expressed as oxide of molybdenum MOO3 relative to the total weight of the hydrotreating catalyst, on a mineral support.

The support for said hydrotreating catalyst is advantageously chosen from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof. Said support may also contain doping compounds, in particular oxides chosen from boron oxide, in particular boron trioxide, zirconia, ceria, titanium oxide, phosphoric anhydride and a mixture of these oxides. . Preferably, said hydrotreating catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron. When phosphoric anhydride P2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. When boron trioxide B2O5 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may for example be a y (gamma) or P (eta) alumina.

Said hydrotreating catalyst is for example in the form of extrudates.

Advantageously, said hydrotreating catalyst used in step b) of the process has a specific surface area greater than or equal to 250 m ² /g, preferably greater than or equal to 300 m ² /g. The specific surface of said hydrotreating catalyst is advantageously less than or equal to 800 m ² /g, preferably less than or equal to 600 m ² /g, in particular less than or equal to 400 m ² /g. The specific surface of the hydrotreating catalyst is measured by the BET method, that is to say the specific surface determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established from the BRUNAUER-EMMETT- TELLER described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938). Such a specific surface makes it possible to further improve the removal of contaminants, in particular of metals such as silicon.

According to another aspect of the invention, the hydrotreating catalyst as described above further comprises one or more organic compounds containing oxygen and/or nitrogen and/or sulfur. Such a catalyst is often designated by the term "additive catalyst". Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulphone, sulphoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or even compounds including a furan ring or even sugars.

Hydrotreatment step b) advantageously allows optimized treatment of the hydrogenated effluent 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 resulting from stage a), the hydrodemetallization of said hydrogenated effluent and the capture of metals, in particular silicon, still present in the hydrogenated effluent. Stage b) of hydrotreatment also allows the hydrodenitrogenation (HDN) of the hydrogenated effluent, i.e. the conversion of the nitrogenous species still present in the hydrogenated effluent. Preferably, the nitrogen content of the hydrotreatment effluent at the end of step b) is less than or equal to 10 ppm by weight.

In a preferred embodiment of the invention, said hydrotreating reaction section comprises several fixed bed reactors, preferably between two and five, very preferably between two and four, fixed bed reactors, each having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, and advantageously operating in series and/or in parallel and/or in switchable mode (or PRS) and/or in swing mode. The different possible operating modes, PRS mode (or lead and lag) and swing mode, and are well known to those skilled in the art and are advantageously defined above. The advantage of a hydrotreatment reaction section comprising several reactors lies in an optimized treatment of the hydrogenated effluent, while making it possible to reduce the risks of clogging of the catalytic bed(s) and therefore to avoid stopping the unit due to clogging.

According to a very preferred embodiment of the invention, said hydrotreating reaction section comprises, preferably consists of:

- (b1) two fixed-bed reactors operating in swing or switchable mode, preferably in PRS mode, each of the two reactors preferably having a catalytic bed advantageously comprising a hydrotreating catalyst preferably chosen from known hydrodemetallization catalysts, silicon capture and combinations thereof, and

- (b2) at least one fixed-bed reactor, preferably one reactor, located downstream of the two reactors (b1), and advantageously operating in series with the two reactors (b1), said fixed-bed reactor (b2) having between 1 and 5 catalytic beds arranged in series and each comprising between one and ten hydrotreating catalyst(s) of which at least one of said hydrotreating catalysts advantageously comprises a support and at least one metallic element preferably comprising at least one element from group VIII , preferably chosen from nickel and cobalt, and/or at least one element from group VI B, preferably chosen from molybdenum and tungsten.

Optionally, step b) can implement a heating section located upstream of the hydrotreatment reaction section and in which the hydrogenated effluent from step a) is heated to reach a temperature suitable for the hydrotreatment , that is to say a temperature between 250 and 430°C. Said optional heating section can thus comprise one or more exchangers, preferably allowing heat exchange between the hydrogenated effluent and the hydrotreatment effluent, and/or a preheating furnace.

Advantageously, stage b) of hydrotreatment allows the total hydrogenation of the olefins present in the initial charge and those possibly obtained after stage a) of selective hydrogenation, but also the conversion at least in part of other impurities present in the load, such as aromatic compounds, metal compounds, sulfur compounds, nitrogen compounds, halogenated compounds (in particular chlorinated compounds), oxygenated compounds. Step b) can also make it possible to further reduce the content of contaminants, such as that of metals, in particular the silicon content. Hydrocracking step c) (first hydrocracking step)

According to the invention, the treatment process comprises a first stage c) of hydrocracking, advantageously in a fixed bed, of said hydrotreated effluent from stage b), in the presence of hydrogen and of at least one hydrocracking catalyst , to obtain a hydrocracked effluent.

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

Advantageously, said step c) is implemented in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, catalyst(s) d hydrocracking. When a reactor comprises several catalytic beds, that is to say at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are arranged in series in said reactor.

Stage b) of hydrotreatment and stage c) of hydrocracking can advantageously be carried out in the same reactor or in different reactors. In the case where they are carried out in the same reactor, the reactor comprises several catalytic beds, the first catalytic beds comprising the hydrotreating catalyst(s) and the following catalytic beds comprising the hydrocracking catalyst(s).

Said hydrocracking reaction section is fed at least with said hydrotreated effluent from step b) and a gas stream comprising hydrogen, advantageously at the level of the first catalytic bed of the first reactor in operation.

Advantageously, said hydrocracking reaction section is implemented at a pressure equivalent to that used in the reaction section of stage a) of selective hydrogenation or stage b) of hydrotreatment. Thus, said hydrocracking reaction section is advantageously carried out at a hydrotreating temperature between 250 and 480°C, preferably between 320 and 450°C, at a hydrogen partial pressure between 1.5 and 25.0 MPa abs., preferably between 2 and 20 MPa abs., and at an hourly volume rate (WH) between 0.1 and 10.0 h ¹ , preferably between 0.1 and 5.0 h ¹ , preferably between 0, 2 and 4: ¹ a.m. According to the invention, the “hydrocracking temperature” corresponds to an average temperature in the hydrocracking reaction section of step c) and of step f) respectively. In particular, it corresponds to the Weight Average Bed Temperature (WABT) according to the established Anglo-Saxon term, well known to those skilled in the art. The hydrocracking temperature is advantageously determined as a function of the catalytic systems, of the equipment, of the configuration thereof, used. For example, the hydrocracking temperature (or WABT) is calculated as follows:

WABT - (Xaojcâs + 2 x T _¾j d }/3 with T _inlet : the temperature of the hydrogenated effluent at the inlet of the hydrocracking reaction section, T _SO rtie: the temperature of the effluent at the outlet of the reaction section d hydrocracking.

The hourly volumetric speed (WH) is defined here as the ratio between the hourly volumetric flow rate of the hydrogenated effluent from stage a) per volume of catalyst(s). The hydrogen coverage in stage c) is advantageously between 80 and 2000 Nm ³ of hydrogen per m ³ of fresh charge which supplies stage a), and preferably between 200 and 1800 Nm ³ of hydrogen per m ³ of fresh load which supplies step a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen taken under normal conditions of temperature and pressure compared to the volume flow rate of fresh charge which supplies stage a), that is to say of charge comprising a plastics pyrolysis oil, or by the optionally pretreated charge, which feeds stage a) (in normal m ³ , denoted Nm ³ , of H2 per m ³ of fresh charge). The hydrogen can consist of a make-up and/or of recycled hydrogen resulting in particular from stage d) of separation.

Preferably, an additional gas stream comprising hydrogen is advantageously introduced at the inlet of each reactor, in particular operating in series, and/or at the inlet of each catalytic bed from the second catalytic bed of the hydrocracking reaction section. These additional gas streams are also called cooling streams. They make it possible to control the temperature in the hydrocracking reactor in which the reactions implemented are generally very exothermic. In one embodiment making it possible to maximize the production of a naphtha cut comprising compounds having a boiling point less than or equal to 175° C., the operating conditions used in stage c) of hydrocracking generally make it possible to achieve conversions per pass, into products having at least 80% by volume of products having boiling points below 175°C, preferably below 160°C and preferably below 150°C, above 15% by weight and even more preferably between 20 and 95% by weight.

Stage c) of hydrocracking thus does not make it possible to transform all the compounds having a boiling point greater than 175°C into compounds having a boiling point less than or equal to 175°C. After fractionation step e), there therefore remains a more or less significant proportion of compounds with a boiling point above 175°C which is sent to the second hydrocracking step f).

In accordance with the invention, stage c) of hydrocracking operates in the presence of at least one hydrocracking catalyst.

The hydrocracking catalyst(s) used in step c) hydrocracking are conventional hydrocracking catalysts known to those skilled in the art, of the bifunctional type combining an acid function with a hydro- dehydrogenating agent and optionally at least one binder matrix. The acid function is provided by supports with a large surface area (generally 150 to 800 m ² /g) exhibiting surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites. The hydrodehydrogenating function is provided by at least one metal from group VI B of the periodic table and/or at least one metal from group VIII.

Preferably, the hydrocracking catalyst(s) used in step c) comprise a hydro-dehydrogenating function comprising at least one group VIII metal chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, and preferably from cobalt and nickel. Preferably, said catalyst(s) also comprise at least one metal from group VI B chosen from chromium, molybdenum and tungsten, alone or as a mixture, and preferably from molybdenum and tungsten. Hydro-dehydrogenating functions of the NiMo, NiMoW, NiW type are preferred. Preferably, the group VIII metal content in the hydrocracking catalyst(s) is advantageously between 0.5 and 15% by weight and preferably between 1 and 10% by weight, the percentages being expressed as percentage by weight of oxides relative to the total weight of the catalyst.

Preferably, the metal content of group VI B in the hydrocracking catalyst(s) is advantageously between 5 and 35% by weight, and preferably between 10 and 30% by weight, the percentages being expressed as percentage by weight of oxides relative to the total weight of the catalyst.

The hydrocracking catalyst(s) used in step c) may also optionally comprise at least one promoter element deposited on the catalyst and chosen from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (preferred chlorine, fluorine), optionally at least one element from group VII B (preferred manganese), and optionally at least one element from group VB (preferred niobium).

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

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

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

In the case where said catalyst comprises a zeolite, the zeolite content in the hydrocracking catalyst(s) is advantageously between 0.1 and 80% by weight, preferably between 3 and 70% by weight, the percentages being expressed as a percentage of zeolite relative to the total weight of the catalyst. A preferred catalyst comprises, and preferably consists of, at least one Group VI B metal and optionally at least one non-noble Group VIII metal, at least one promoter element, and preferably phosphorus, at least one Y zeolite and at least one alumina binder.

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

Another preferred catalyst includes, and preferably consists of, nickel, tungsten, alumina and silica-alumina.

Another preferred catalyst includes, and preferably consists of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

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

According to another aspect of the invention, the hydrocracking catalyst as described above further comprises one or more organic compounds containing oxygen and/or nitrogen and/or sulfur. Such a catalyst is often designated by the term "additive catalyst". Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulphone, sulphoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or even compounds including a furan ring or even sugars.

The preparation of the catalysts of stages a), b) or c) is known and generally comprises a stage of impregnation of group VIII and group VIB metals when present, and optionally phosphorus and/or boron on the support, followed by drying, then optionally by calcination. In the case of an additive catalyst, the preparation is generally carried out by simple drying without calcination after introduction of the organic compound. Here, calcination means a heat treatment under a gas containing air or oxygen at a temperature greater than or equal to 200°C. Before their use in a stage of the process, the catalysts are generally subjected to sulfurization in order to form the active species. The catalyst of step a) can also be a catalyst used in its reduced form, thus involving a reduction step in its preparation. Optionally, step c) can implement a heating section located upstream of the hydrocracking reaction section and in which the hydrotreated effluent from step b) is heated to reach a temperature suitable for hydrocracking. , that is to say a temperature between 250 and 480°C. Said optional heating section may thus comprise one or more exchangers, preferably allowing heat exchange between the hydrotreated effluent and the hydrocracked effluent, and/or a preheating furnace.

Separation step d)

According to the invention, the treatment process comprises a step d) of separation, advantageously implemented in at least one washing/separation section, supplied at least with the hydrocracked effluent from step c) and an aqueous solution , to obtain at least one gaseous effluent, one aqueous effluent and one hydrocarbon effluent.

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

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

The hydrocarbon effluent from step d) comprises hydrocarbon compounds and advantageously corresponds to the plastics pyrolysis oil of the feed, or to the plastics pyrolysis oil and the conventional petroleum or biomass feed fraction. - treated with pyrolysis oil, in which at least some of the heavy compounds have been converted into lighter compounds in order to maximize the naphtha cut. The hydrocarbon effluent is also freed at least in part of its impurities, in particular its olefinic (di- and mono-olefin), metallic and halogenated impurities.

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

Depending on the content of chlorinated compounds in the initial charge to be treated, a stream containing an amine such as, for example, monoethanolamine, diethanolamine and/or monodiethanolamine can be injected upstream of stage a) of selective hydrogenation, between stage a) of selective hydrogenation and stage b) of hydrotreatment and/or between stage c) of hydrocracking and stage d) of separation, preferably upstream of stage a) selective hydrogenation, in order to ensure a sufficient quantity of ammonium ions to combine the chloride ions formed during the hydrotreatment stage, thus making it possible to limit the formation of hydrochloric acid and thus to limit corrosion downstream of the separation section.

Advantageously, step d) of separation comprises an injection of an aqueous solution, preferably an injection of water, into the hydrocracked effluent from step c), upstream of the washing/separation section, of so as to at least partially dissolve ammonium chloride salts and/or hydrochloric acid and thus improve the elimination of chlorinated impurities and reduce the risks of clogging due to an accumulation of ammonium chloride salts.

Separation step d) is advantageously carried out at a temperature of between 50 and 370°C, preferably between 100 and 340°C, more preferably between 200 and 300°C. Advantageously, step d) of separation is carried out at a pressure close to that implemented in steps a) and/or b) and/or c), preferably between 1.0 and 10.0 MPa, so to facilitate the recycling of hydrogen.

The washing/separation section of step d) can at least partly be carried out in common or separate washing and separation equipment, this equipment being well known (separator drums which can operate at different pressures and temperatures, pumps, heat exchangers heat pumps, washing columns, etc.).

In a possible embodiment of the invention, taken in addition to or in isolation from other embodiments of the invention described, step d) of separation comprises the injection of an aqueous solution into the hydrocracked effluent from of step c), followed by washing/separation section advantageously comprising a separation phase making it possible to obtain at least one aqueous effluent loaded with ammonium salts, one washed liquid hydrocarbon effluent and one partially washed gaseous effluent. The aqueous effluent charged with ammonium salts and the washed liquid hydrocarbon effluent can then be separated in a settling flask in order to obtain said hydrocarbon effluent and said aqueous effluent. Said partially washed gaseous effluent can be introduced in parallel into a washing column where it circulates countercurrent to an aqueous flow, preferably of the same nature as the aqueous solution injected into the hydrocracked effluent, which makes it possible to eliminate at least part, preferably entirely, the hydrochloric acid contained in G partially washed gaseous effluent and thus obtaining said gaseous effluent, preferably comprising essentially hydrogen, and an acidic aqueous stream. Said aqueous effluent from the settling flask can optionally be mixed with said acid aqueous stream, and be used, optionally mixed with said acid aqueous stream in a water recycling circuit to supply step d) of separation with said aqueous solution upstream of the washing/separation section and/or in said aqueous stream in the washing column. Said water recycling circuit may comprise a make-up of water and/or of a basic solution and/or a purge making it possible to evacuate the dissolved salts.

In another possible embodiment of the invention, taken separately or in combination with other embodiments of the invention described, step d) of separation can advantageously comprise a "high pressure" washing/separation section which operates at a pressure close to the pressure of step a) of selective hydrogenation and/or of step b) of hydrotreating and/or of step c) of hydrocracking, in order to facilitate the recycling of 'hydrogen. This optional "high pressure" section of step d) can be supplemented by a "low pressure" section, in order to obtain a liquid hydrocarbon fraction devoid of part of the gases dissolved at high pressure and intended to be treated directly in a steam cracking process or optionally be sent to step e) fractionation.

The gas fraction(s) resulting from step d) of separation may (may) be subject to purification(s) and additional separation(s) with a view to recovering at least one gas rich in hydrogen which can be recycled upstream of stages a) and/or b) and/or c) and/or light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent separately or as a mixture in a or furnaces of stage h) of steam cracking so as to increase the overall yield of olefins. The hydrocarbon effluent from step d) of separation is sent, in part or in whole, preferably in whole, to step e) of fractionation.

Step e) of fractionation

The process according to the invention comprises a step of fractionating all or part, preferably all, of the hydrocarbon effluent from step d), to obtain at least one gas stream and at least two liquid hydrocarbon streams , said two liquid hydrocarbon streams being at least one naphtha cut comprising compounds having a boiling point of less than or equal to 175°C, in particular between 80 and 175°C, and a hydrocarbon cut comprising compounds having a boiling above 175°C. Stage e) makes it possible in particular to eliminate the gases dissolved in the liquid hydrocarbon effluent, such as for example ammonia, hydrogen sulphide and light hydrocarbons having 1 to 4 carbon atoms.

Fractionation step e) is advantageously carried out at a pressure of less than or equal to 1.0 MPa abs., preferably between 0.1 and 1.0 MPa abs. According to one embodiment, step e) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit comprising a reflux drum. Said stripping column is fed by the liquid hydrocarbon effluent from step d) and by a stream of steam. The liquid hydrocarbon effluent from stage d) can optionally be reheated before entering the stripping column. Thus, the lightest compounds are entrained at the top of the column and in the reflux circuit comprising a reflux drum in which a gas/liquid separation takes place. The gaseous phase, which includes the light hydrocarbons, is withdrawn from the reflux drum, in a gas stream. The naphtha cut comprising compounds having a boiling point less than or equal to 175° C. is advantageously withdrawn from the reflux drum. The hydrocarbon cut comprising compounds having a boiling point above 175°C is advantageously drawn off at the bottom of the stripping column.

According to other embodiments, step e) of fractionation can implement a stripping column followed by a distillation column or only a distillation column. The naphtha cut comprising compounds having a boiling point less than or equal to 175° C. can be sent, in whole or in part, to a steam cracking unit, at the end of which olefins can be (re)formed to participate to the formation of polymers. It can also be sent to a fuel pool, for example naphtha pool, or even be sent, in part, to stage h) of recycling.

The hydrocarbon cut comprising compounds having a boiling point above 175° C. is at least partly sent to the second stage f) of hydrocracking.

According to a preferred mode, the naphtha cut comprising compounds having a boiling point less than or equal to 175° C., all or part, is sent to a steam cracking unit, while the cut comprising compounds having a boiling point higher than 175° C. is sent to stage f) of hydrocracking.

In another particular embodiment, step e) of fractionation can make it possible to obtain, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point less than or equal to 175° C., preferably between 80 and 175°C, and a kerosene cut comprising compounds having a boiling point above 175°C and less than or equal to 280°C, optionally a diesel cut comprising compounds having a boiling point above 280°C and less than 385° C. and a hydrocarbon cut comprising compounds having a boiling point greater than or equal to 385° C., referred to as a heavy hydrocarbon cut. The naphtha cut can be sent, in whole or in part, to a steam cracking unit and/or to the naphtha pool from conventional petroleum feedstocks, it can also be sent to stage h) recycling; the kerosene cut and/or the diesel cut can also be, in whole or in part, either sent to a steam cracking unit, or respectively to a kerosene or diesel pool from conventional petroleum feedstocks, or be recycled in the process in the same way than the naphtha cup; the heavy cut is sent, at least in part, to the second stage f) of hydrocracking.

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

The gas fraction(s) resulting from stage e) of fractionation may (may) be subject to purification(s) and additional separation(s) with a view to recovering at least light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent separately or as a mixture to one or more furnaces of stage i) of steam cracking so as to increase the overall yield of olefins.

Hydrocracking step f) (second hydrocracking step)

According to the invention, the treatment process comprises a second stage f) of hydrocracking, advantageously in a fixed bed, of at least part of said hydrocarbon cut comprising compounds having a boiling point above 175° C. resulting from step e), in the presence of hydrogen and at least one hydrocracking catalyst, to obtain a second hydrocracked effluent.

Advantageously, step f) implements the hydrocracking reactions well known to those skilled in the art, and more particularly makes it possible to convert at least part of the cut comprising compounds having a boiling point above 175° C to compounds with a boiling point less than or equal to 175°C. Other reactions, such as hydrogenation of olefins, aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrogenation, etc. can continue.

Advantageously, said step f) is implemented in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, catalyst(s) d hydrocracking. When a reactor comprises several catalytic beds, that is to say at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are arranged in series in said reactor.

Said hydrocracking reaction section is fed with at least a part of the cut comprising compounds having a boiling point above 175° C. and a stream gas comprising hydrogen, advantageously at the level of the first catalytic bed of the first reactor in operation.

Advantageously, said second hydrocracking reaction section is implemented at a pressure equivalent to that used in the reaction section of stage a) of selective hydrogenation or stage b) of hydrotreatment or stage c) of first hydrocracking.

Thus, said hydrocracking reaction section is advantageously carried out at a hydrotreating temperature between 250 and 480°C, preferably between 320 and 450°C, at a hydrogen partial pressure between 1.5 and 25.0 MPa abs., preferably between 3 and 20 MPa abs., and at an hourly volume rate (WH) between 0.1 and 10.0 h ¹ , preferably between 0.1 and 5.0 h ¹ , preferably between 0, 2 and 4: ¹ a.m. The hourly volumetric speed (WH) is defined here as the ratio between the hourly volumetric flow rate of the hydrogenated effluent from stage a) per volume of catalyst(s). The hydrogen coverage in stage f) is advantageously between 80 and 2000 Nm ³ of hydrogen per m ³ of fresh charge which supplies stage a), and preferably between 200 and 1800 Nm ³ of hydrogen per m ³ of fresh load which supplies step a). The hydrogen coverage is defined here as the ratio of the volume flow rate of hydrogen taken under normal conditions of temperature and pressure compared to the volume flow rate of fresh charge which supplies stage a), that is to say of charge comprising a plastics pyrolysis oil, or by the optionally pretreated charge, which feeds stage a) (in normal m ³ , denoted Nm ³ , of H2 per m ³ of fresh charge). The hydrogen can consist of a make-up and/or of recycled hydrogen resulting in particular from stage d) of separation.

Preferably, an additional gas stream comprising hydrogen is advantageously introduced at the inlet of each reactor, in particular operating in series, and/or at the inlet of each catalytic bed from the second catalytic bed of the hydrocracking reaction section. These additional gas streams are also called cooling streams. They make it possible to control the temperature in the hydrocracking reactor in which the reactions implemented are generally very exothermic.

These operating conditions used in step f) of the process according to the invention generally make it possible to achieve conversions per pass, into products having at least 80% by volume of compounds having boiling points less than or equal to 175 ° C. , preferably below 160°C and preferably below 150°C, above 15% by weight and even more preferably between 20 and 80% by weight. Nevertheless, the conversion per pass in step f) is kept moderate in order to maximize the selectivity for compounds of the naphtha cut (having a boiling point less than or equal to 175° C., in particular between 80 and less than or equal to 175°C). Conversion per pass is limited by the use of a high recycle rate on the second stage hydrocracking loop. This rate is defined as the ratio between the feed rate of step f) and the feed rate of step a), preferably this ratio is between 0.2 and 4, preferably between 0, 5 and 2.5.

In accordance with the invention, stage f) of hydrocracking operates in the presence of at least one hydrocracking catalyst. Preferably, the second stage hydrocracking catalyst is chosen from the conventional hydrocracking catalysts known to those skilled in the art, such as those described above in stage c) of hydrocracking. The hydrocracking catalyst used in said step f) may be identical to or different from that used in step c), and preferably different.

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

Optionally, step f) can implement a heating section located upstream of the hydrocracking reaction section and in which said hydrocarbon fraction comprising compounds having a boiling point above 175° C. resulting from step e) is heated to reach a temperature suitable for hydrocracking, that is to say a temperature between 250 and 480°C. Said possible heating section can thus comprise one or more exchangers, and/or a preheating furnace.

Stage g) of recycling the second hydrocracked effluent

In accordance with the invention, the method comprises a step g) of recycling at least part and preferably all of said second hydrocracked effluent from step f) in step d) of separation. A purge can be installed on the recycle of said second hydrocracked effluent from step f). Depending on the operating conditions of the process, said purge may be between 0 and 10% by weight of said hydrocracked effluent from stage f) relative to the incoming feed, and preferably between 0.5% and 5% by weight.

Step h) (optional) for recycling the hydrocarbon effluent from step d) and/or the naphtha cut having a boiling point less than or equal to 175°C from step e)

The process according to the invention may comprise stage h) of recycling, in which a fraction of the hydrocarbon effluent resulting from stage d) of separation or a fraction of the naphtha cut having a boiling point lower than or equal to at 175° C. from step e) of fractionation, is recovered to form a recycle stream which is sent upstream of or directly to at least one of the reaction steps of the process according to the invention, in particular to the stage a) of selective hydrogenation and/or stage b) of hydrotreatment. Optionally, a fraction of the recycle stream can be sent to the optional pretreatment step aO). Preferably, the method according to the invention comprises step h) of recycling.

Preferably, at least a fraction of the hydrocarbon effluent from step d) of separation or from the naphtha cut having a boiling point less than or equal to 175° C. from step e) of fractionation feeds the step b) hydrotreating.

Advantageously, the quantity of the recycle stream is adjusted so that the weight ratio between the recycle stream and the charge comprising a plastics pyrolysis oil, that is to say the charge to be treated supplying the overall process, is lower 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 more preferably greater than or equal to 0.1. Very preferably, the quantity of the recycle stream is adjusted so that the weight ratio between the recycle stream and the charge comprising a plastics pyrolysis oil is between 0.2 and 5.

Advantageously, for the start-up phases of the process, a hydrocarbon cut external to the process can be used as recycle stream. A person skilled in the art will then know how to choose said hydrocarbon cut. The recycling of part of the product obtained towards or upstream of at least one of the reaction stages of the process according to the invention advantageously makes it possible on the one hand to dilute the impurities and on the other hand to control the temperature in the stage or stages. (s) reaction (s), in which (the) which (s) of the reactions involved can be strongly exothermic.

According to a preferred embodiment of the invention, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, the sequence of steps, and preferably in the order given, a) selective hydrogenation, b) hydrotreatment, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling of the hydrocracked effluent in stage d), for producing an effluent of which at least a part is compatible for treatment in a steam cracking unit.

According to another preferred embodiment of the invention, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, the sequence of steps, and preferably in the order given, aO ) pretreatment, a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling of the hydrocracked effluent to the step d), to produce an effluent of which at least a part is compatible for treatment in a steam cracking unit.

According to a third preferred embodiment of the invention, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, the sequence of steps, and preferably in the order given, a ) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling of the hydrocracked effluent in step d), h) recycling part of the cut comprising compounds having a boiling point less than or equal to 175° C. in stages a) and/or b), to produce an effluent of which at least a part is compatible for a treatment in a steam cracking unit.

According to a fourth preferred embodiment of the invention, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, the sequence of steps, and preferably in the order given, aO ) pretreatment, a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking and g) recycling of the hydrocracked effluent to the step d), h) of recycling part of the cut comprising compounds having a boiling point less than or equal to 175° C. in stages a) and/or b), to produce an effluent of which at least a part is compatible for treatment in a steam cracking unit.

Said hydrocarbon effluent or said hydrocarbon stream(s) thus obtained by treatment according to the process of the invention of an oil for the pyrolysis of plastics, exhibit(s) a composition compatible with the specifications of a charge at the inlet of a steam cracking unit. In particular, the composition of the hydrocarbon effluent or of said hydrocarbon stream(s) is preferably such that:

- the total content of metallic elements is less than or equal to 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, with: a silicon (Si) element content less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.6 ppm by weight , and a content of the element iron (Fe) less than or equal to 100 ppb weight, - the sulfur content is less than or equal to 500 ppm weight, preferably less than or equal to 200 ppm weight,

- the nitrogen content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight and preferably less than or equal to 5 ppm by weight

- the asphaltene content is less than or equal to 5.0 ppm by weight, - the total chlorine element content is less than or equal to 10 ppm by weight, preferably less than 1.0 ppm by weight,

- the content of olefinic compounds (mono- and di-olefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.1% by weight. The contents are given in relative weight concentrations, percentage (%) by weight, part(s) per million (ppm) weight or part(s) per billion (ppb) weight, relative to the total weight of the stream considered.

The method according to the invention therefore makes it possible to treat the plastic pyrolysis oils to obtain an effluent which can be injected, in whole or in part, into a steam cracking unit. Step i) steam cracking (optional)

The naphtha cut comprising compounds having a boiling point less than or equal to 175° C. resulting from stage e), all or in part, can be sent to a stage i) of steam cracking.

Advantageously, the gas fraction(s) resulting from step d) of separation and/or e) of fractional and containing ethane, propane and butane, may (may) be wholly or partially also sent to stage i) of steam cracking.

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

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

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

According to one or more preferred embodiment(s) of the invention, taken separately or combined together, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, sequence of the steps described above, and preferably in the order given, that is to say: a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e ) fractionation, f) hydrocracking, g) recycling of the second hydrocracked effluent in step d), and step i) steam cracking.

According to a preferred mode, the process for treating a charge comprising a plastics pyrolysis oil comprises, preferably consists of, the sequence of the steps described above, and preferably in the order given, that is- i.e. aO) pretreatment, a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling of the second effluent hydrocracked in step d), g) recycling at least part of the naphtha cut comprising compounds having a boiling point less than or equal to 175° C. in steps a) and/or b), and step i) of steam cracking.

The process according to the invention, when it comprises this step i) of steam cracking, thus makes it possible to obtain, from plastic pyrolysis oils, for example plastic waste, olefins which can be used as monomers for the synthesis of new polymers contained in plastics, with relatively satisfactory yields, without clogging or corrosion of the units. Analytical methods used

The analysis methods and/or standards used to determine the characteristics of the various streams, in particular of the feed to be treated and of the effluents, are known to those skilled in the art. They are specifically listed below: Table 1

LIST OF FIGURES

The mention of the elements referenced in Figure 1 allows a better understanding of the invention, without it being limited to the particular embodiments illustrated in Figure 1. The different embodiments presented can be used alone or in combination. with each other, without limitation of combination.

Figure 1 shows the diagram of a particular embodiment of the method of the present invention, comprising:

- a stage a) of selective hydrogenation of a hydrocarbon feed resulting from the pyrolysis of plastics 1, in the presence of a hydrogen-rich gas 2 and optionally of an amine supplied by the stream 3, carried out in at least one reactor in a fixed bed comprising at least one selective hydrogenation catalyst, to obtain an effluent 4;

- a step b) of hydrotreating the effluent 4 from step a), in the presence of hydrogen 5, carried out in at least one fixed-bed reactor comprising at least one hydrotreating catalyst, to obtain a hydrotreated effluent 6;

- a first step c) of hydrocracking the effluent 6 from step c), in the presence of hydrogen 7, carried out in at least one fixed-bed reactor comprising at least one hydrocracking catalyst, to obtain a first hydrocracked effluent 8;

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

- a step e) of fractionation of the liquid hydrocarbon fraction 12 making it possible to obtain at least one gaseous fraction 13, a naphtha cut 14 comprising compounds having a boiling point less than or equal to 175° C. and a cut 15 comprising compounds with a boiling point above 175°C;

- a second step f) of hydrocracking at least part of the cut 15a comprising compounds having a boiling point above 175° C. resulting from step e), in the presence of hydrogen-16, carried out in at least one fixed-bed reactor comprising at least one hydrocracking catalyst, to obtain a second hydrocracked effluent 17; the other part of the cut 15 constitutes the purge 15b;

- a step of recycling the second hydrocracked effluent 17 in step d) of separation. Instead of injecting the amine stream 3 at the input of stage a) of selective hydrogenation, it is possible to inject it at the input of stage b) of hydrotreatment, at the input of stage c ) of hydrocracking, at the inlet of stage d) of separation or even of not injecting it, depending on the characteristics of the charge. At the end of step e), at least part of the naphtha cut 14 comprising compounds having a boiling point less than or equal to 175° C. is sent to a steam cracking process (not shown) .

Optionally, part of the naphtha cut 14 comprising compounds having a boiling point less than or equal to 175° C. resulting from stage e) constitutes a recycle stream which feeds stage a) of selective hydrogenation (fraction 14a), and step b) of hydrotreating (fraction 14b).

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

Example 1 (in accordance with the invention)

Feedstock 1 treated in the process is a plastics pyrolysis oil (that is to say comprising 100% by weight of said plastics pyrolysis oil) having the characteristics indicated in Table 2. Table 2: characteristics of the load

(1) MAV method described in the article: C. Lépez-Garcia 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, p. 57-68

Charge 1 is subjected to a stage a) of selective hydrogenation carried out in a fixed-bed reactor and in the presence of hydrogen 2 and a selective hydrogenation catalyst of the NiMo on alumina type under the conditions indicated in table 3 . Table 3: conditions of stage a) of selective hydrogenation

At the end of stage a) of selective hydrogenation, all of the diolefins initially present in the feed have been converted.

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

Table 4: conditions of stage b) of hydrotreatment

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

The effluent 8 from stage c) of hydrocracking is subjected to a stage d) of separation according to the invention in which a flow of water is injected into the effluent from stage c) of hydrocracking ; the mixture is then sent to stage d) of separation and is treated in an acid gas scrubbing column. A gas fraction 10 is obtained at the top of the acid gas scrubbing column while at the bottom, a two-phase separator drum makes it possible to separate an aqueous phase and a liquid phase. The gas scrubbing column and the two-phase separator are operated at high pressure. The liquid phase is then sent to a low-pressure drum so as to recover a second gaseous fraction which is purged and a liquid effluent. The liquid effluent 12 obtained at the end of step d) of separation is sent to a step e) of fractionation comprising a stripping column and a distillation column in order to obtain a fraction having a lower boiling point. or equal to 175°C (PI-175°C fraction) and a fraction having a boiling point greater than 175°C (175°C+ fraction). The 175°C+ fraction from stage e) of fractionation is sent to the second stage f) of hydrocracking so as to increase the conversion of compounds having a boiling point above 175°C. A small part of the 175° C.+ fraction is not sent to the second stage f) hydrocracking so as to avoid the accumulation of polyaromatic compounds which could be coke precursors (purge 15b). The volume flow rate of the 175°C+ fraction from stage e) of fractionation and sent to the second stage f) hydrocracking is equal to 80% of the volume flow rate of the liquid effluent from stage b) of hydrotreatment and feeding the first stage c) of hydrocracking. The second hydrocracking step f) is carried out in a fixed bed and in the presence of hydrogen 16 and a zeolitic hydrocracking catalyst comprising NiMo under the conditions presented in Table 6.

Table 6: conditions of the second stage f) of hydrocracking

The effluent 17 from the second hydrocracking step f) is mixed with the effluent 8 from the first hydrocracking step c). The two effluents are subjected to a step d) of separation then a step e) of fractionation, these two steps being common to the two effluents and being carried out as described above.

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

Table 7: yields of the various products and fractions obtained at the output of stages c) and f) of hydrocracking

The H ₂ S and NH ₃ compounds are mainly eliminated in the form of salts in the aqueous phase eliminated in stage d) of separation.

The treatment of the charge according to the steps of the invention, and in particular through steps c) and f) of hydrocracking, makes it possible to obtain a very high yield of naphtha-type PI-175°C fraction.

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

Table 8: characteristics of the PI-175°C, 175°C+ fractions

The PI-175°C and 175°C+ liquid fractions both have compositions compatible with a steam cracking unit since:

- they do not contain olefins (mono- and di-olefins);

- they have very low chlorine element contents (respectively an undetected content and a content of 25 ppb by weight) and below the limit required for a steam cracker charge;

- the metal contents, in particular iron (Fe), are also very low (metal contents not detected for the PI-175°C fraction and < 1 ppm weight for the 175°C+ fraction; Fe contents not detected for the PI-175°C fraction and 50 ppb weight for the 175°C+ fraction) and below the limits required for a steam cracker feed (£ 5.0 ppm weight, very preferably £ 1 ppm weight for metals; £ 100 ppb weight for Fe);

- finally they contain sulfur (< 2 ppm weight for the PI-175°C fraction and < 2 ppm weight for the 175°C+ fraction) and nitrogen (< 0.5 ppm weight for the PI-175° fraction C and <3 ppm by weight for the 175°C+ fraction) at contents well below the limits required for a steam cracker charge (£500 ppm by weight, preferably £200 ppm by weight for S and N).

The PI-175°C liquid fraction obtained is therefore then sent to a stage i) of steam cracking (cf. table 9). Table 9: conditions of the steam cracking step

The effluents from the various steam cracking furnaces are subjected to a separation stage making it possible to recycle the saturated compounds to the steam cracking furnaces and to obtain the yields presented in table 10 (yield = % of mass of product relative to the mass of the fraction PI-175°C upstream of the steam cracking step, denoted % m/m). Table 10: yields of the steam cracking step

Considering the yield of 93% obtained for the liquid fraction at 175°C+ during the process for treating the pyrolysis oil coming out of the hydrocracking stages (see Table 7), it is possible to determine the overall yields of the products from stage i) of steam cracking with respect to the initial charge of plastic pyrolysis oil type introduced in stage a):

Table 11: overall process yields of products from the steam cracking step of the PI-175°C fraction

When the PI-175°C fraction is sent to the steam cracking unit, the process according to the invention makes it possible to achieve overall mass yields of ethylene and propylene respectively of 31.9% and 17.4% compared to the mass quantity of initial plastics pyrolysis oil type filler. In addition, the specific sequence of steps upstream of the steam cracking step makes it possible to limit the formation of coke and to avoid the corrosion problems which would have appeared if the chlorine had not been eliminated.

Example 2 (not in accordance with the invention)

In this example, the load to be processed is identical to that described in Example 1 (see Table 2).

It undergoes stages a) of selective hydrogenation, b) of hydrotreatment and d) of separation, carried out under the same conditions as those described in Example 1. In this example not in accordance with the invention, the effluent from of the hydrotreating stage is not subjected to the hydrocracking stages c) and f). The liquid effluent obtained at the end of step d) of separation constitutes the PI+ fraction.

The yields of the various products and of the various fractions obtained at the outlet of stage b) of hydrotreatment are indicated in table 12 (the yields being corresponding to the ratios of the quantities by mass of the various products obtained with respect to the mass of feedstock upstream of step a), expressed as a percentage and noted as % m/m).

Table 12: Yields of the various products and fractions obtained at the output of stage b) of hydrotreatment

The characteristics of the PI+ fraction (which corresponds to the liquid effluent) obtained after stage d) of separation are presented in Table 13:

Table 13: characteristics of the PI+ fraction

The PI+ fraction obtained via the sequence of steps a), b) and d) consists of approximately 35% of compounds of naphtha type having a boiling point less than or equal to 175°C. This low yield of naphtha-type compounds having a boiling point less than or equal to 175° C. is due to the absence of hydrocracking steps in this nonconforming example. The PI+ fraction liquid effluent is sent directly to a steam cracking stage i) according to the conditions mentioned in table 14.

Table 14: conditions of the steam cracking step

The effluent from the steam cracking furnace is subjected to a separation stage making it possible to recycle the saturated compounds to the steam cracking furnace and to obtain the yields presented in table 15 (yield = % of mass of product relative to the mass of PI+ fraction upstream of the steam cracking step, denoted % m/m).

Table 15: yields of the steam cracking stage of the PI+ fraction

By considering the obtained yield of 99.5% for the PI+ fraction during the process for treating the pyrolysis oil at the outlet of step b) of hydrotreatment (see Table 12), it is possible to determine the yields total of the products resulting from stage i) of steam cracking with respect to the initial charge of plastic pyrolysis oil type introduced in step a):

Table 16: overall process yields of products from the PI+ fraction steam cracking step

When the PI+ liquid fraction is subjected to a steam cracking step, the process according to the invention makes it possible to achieve overall mass yields of ethylene and propylene respectively of 34.6% and 18.9% relative to the quantity by mass of initial plastics pyrolysis oil type charge.

Claims

1. Process for treating a charge comprising a plastics pyrolysis oil, comprising: a) a selective hydrogenation step implemented in a reaction section fed at least by said charge and a gas stream comprising hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature between 100 and 280° C., a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volume rate between 0.3 and 10.0 h ^-1 , to obtain a hydrogenated effluent; b) a hydrotreating step implemented in a hydrotreating reaction section, implementing at least one fixed bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one catalyst hydrotreatment, said hydrotreatment reaction section being fed at least with said hydrogenated effluent from step a) and a gas stream comprising hydrogen, said hydrotreatment reaction section being implemented at a temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric speed between 0.1 and 10.0 h ¹ , to obtain a hydrotreatment effluent; c) a first hydrocracking stage implemented in a hydrocracking reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed at least with said hydrotreated effluent from step b) and a gas stream comprising hydrogen, said hydrocracking reaction section being implemented at a temperature between 250 and 480°C, a hydrogen partial pressure between 1.5 and 25.0 MPa abs. and an hourly volume rate between 0.1 and 10.0 h ¹ , to obtain a first hydrocracked effluent; d) a separation stage, supplied with the hydrocracked effluent from stage c) and an aqueous solution, said stage being carried out at a temperature between 50 and 370° C., to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent; e) a step of fractionating all or part of the hydrocarbon effluent from step d), to obtain at least one gas stream and at least two liquid hydrocarbon streams, said two liquid hydrocarbon streams being at least one naphtha cut comprising compounds having a boiling point less than or equal to 175° C. and a hydrocarbon cut comprising compounds having a boiling point greater than 175° C.; f) a second hydrocracking stage implemented in a hydrocracking reaction section, implementing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being supplied with at least a portion of said hydrocarbon cut comprising compounds having a boiling point above 175°C from step e) and a gas stream comprising hydrogen, said hydrocracking reaction section being carried out at a temperature between 250 and 480°C, a hydrogen partial pressure between 1.5 and 25.0 MPa abs. and an hourly volumetric speed between 0.1 and 10.0 h ¹ , to obtain a second hydrocracked effluent; g) a step of recycling at least part of said second hydrocracked effluent from step f) in step d) of separation.

2. Method according to the preceding claim, which further comprises a step h) of recycling in which a fraction of the hydrocarbon effluent from step d) of separation or a fraction of the naphtha cut having a lower boiling point or equal to 175° C. from step e) of fractionation is sent to step a) of selective hydrogenation and/or step b) of hydrotreatment.

3. Method according to the preceding claim, in which the quantity of the recycle stream of step h) is adjusted so that the weight ratio between the recycle stream and the charge comprising a plastics pyrolysis oil is less than or equal to 10.

4. Method according to one of the preceding claims, comprising a step aO) of pretreatment of the charge comprising a plastic pyrolysis oil, said pretreatment step being implemented upstream of step a) of selective hydrogenation and comprising a filtration step and/or a water washing step and/or an adsorption step.

5. Method according to one of the preceding claims, in which the reaction section of step a) or b) uses at least two reactors operating in switchable mode.

6. Method according to one of the preceding claims, in which a stream containing an amine is injected upstream of step a).

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

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

9. Process according to one of the preceding claims, in which the said hydrocracking catalyst of step c) or of step f) comprises a support chosen from halogenated aluminas, combinations of boron and aluminum oxides , amorphous silica-aluminas and zeolites and a hydro-dehydrogenating function comprising at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and/or at least one metal from group VIII chosen among iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

10. Process according to the preceding claim, in which the said zeolite is chosen from Y zeolites, alone or in combination, with other zeolites from beta zeolites, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO -11, ZSM-48, ZBM-30, singly or in combination.

11. Process according to one of the preceding claims, in which the naphtha cut comprising compounds having a boiling point less than or equal to 175° C. resulting from stage e), all or in part, is sent to stage i ) of steam cracking carried out in at least one pyrolysis furnace at a temperature between 700 and 900° C. and at a pressure between 0.05 and 0.3 relative MPa.

12. Process according to one of the preceding claims, in which the naphtha cut comprising compounds having a boiling point of less than or equal to 175° C. resulting from step e) is fractionated into a heavy naphtha cut comprising compounds having a boiling point between 80 and 175°C and a light naphtha cut comprising compounds having a boiling point below 80°C, at least part of said heavy cut being sent to an aromatic complex comprising at least one step naphtha reforming.

13. Process according to claim 12, in which at least part of the light naphtha cut is sent to stage i) of steam cracking.

14. Product obtainable by the process according to one of claims 1 to 13.