Treatment of plastic pyrolysis oil involving two-step hydrocracking.

Abstract

The present invention relates to a method for processing plastic pyrolysis oil, the method comprising: (a) selectively hydrogenating the feedstock to obtain a hydrogenated effluent; (b) hydrotreating the hydrogenated effluent to obtain a hydrotreated effluent; (c) performing a first hydrocracking step on the hydrogenated effluent to obtain a first hydrocracked effluent; (d) separating the hydrogenated 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 fraction, and a heavier fraction; (f) performing a second hydrocracking step on the heavier fraction to obtain a second hydrocracked effluent; and (g) recycling at least a portion of the second hydrogenated effluent to the separation step (d).

Description

[Technical Field]

[0001] The present invention relates to a method for treating plastic pyrolysis oil to obtain a hydrocarbon-based effluent, which can be upgraded, for example, at least in part, by direct incorporation into naphtha or diesel pools or as a feedstock for a steam cracking unit. Feedstocks obtained from the pyrolysis of plastic waste may contain relatively large amounts of impurities, in particular olefins (mono- and di-olefins), metals, in particular silicon, and halogens, in particular chlorine; the present invention more particularly relates to a method for treating said feedstock to at least in part remove these impurities and to hydrogenate the feedstock so that it can be upgraded.

[0002] The method according to the invention therefore makes it possible to treat plastic pyrolysis oil to obtain an effluent that can be injected wholly or partially into a steam cracking unit, and therefore makes it possible to upgrade the plastic pyrolysis oil while simultaneously reducing coke formation and therefore the risk of clogging and / or premature loss of activity of the catalyst(s) used in the steam cracking unit, and reducing the risk of corrosion. [Background technology]

[0003] Plastics obtained from collection and sorting channels may undergo a process of pyrolysis to obtain, among other things, pyrolysis oils, which are generally burned to generate electricity or used as fuel for industrial boilers and city heating.

[0004] Another route to upgrading plastic pyrolysis oil is to use it as a feedstock for a steam cracking unit to (re)create olefins, which are the constituent monomers of certain polymers. However, plastic waste is generally a mixture of several polymers, such as polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polystyrene. Furthermore, depending on the application, plastics may contain other compounds in addition to polymers, such as plasticizers, pigments, colorants, or polymerization catalyst residues. Plastic waste may also contain small amounts of biomass, for example, from household waste. As a result, the oil obtained from the pyrolysis of plastic waste often contains many impurities, particularly diolefins, metals, especially silicon, or halogenated compounds, especially chlorine-based compounds, heteroelements, such as sulfur, oxygen, nitrogen, and insoluble substances, at high levels that make it incompatible with steam cracking units or units downstream of the steam cracking unit, especially polymerization and selective hydrogenation processes. These impurities can cause problems in operability, particularly corrosion, coking, or catalyst deactivation, or incompatibility in the application of the target polymer. The presence of diolefins can also cause problems with pyrolysis oil instability, characterized by the formation of gums. Gums and insoluble materials that may be present in pyrolysis oil can cause clogging problems during the process.

[0005] Furthermore, during the steam cracking process, the yield of petrochemically desired light olefins, especially ethylene and propylene, is highly dependent on the quality of the feedstock sent for steam cracking. The Bureau of Mines Correlation Index (BMCI) is often used to characterize hydrocarbon fractions. Overall, higher yields of light olefins are associated with higher paraffin content and / or a decrease in BMCI. Conversely, higher yields of undesirable heavy compounds and / or coke are associated with an increase in BMCI.

[0006] Patent document 1 proposes a very general and relatively complex overall method for recycling plastic waste, starting from the very step of pyrolysis of plastic waste to a steam cracking step. The method of patent application 1 comprises, inter alia, a step of hydrotreating the liquid phase obtained directly from the pyrolysis, preferably under very severe conditions, in particular with regard to temperature, for example at a temperature of 260-300°C, a step of separation of the hydrotreated effluent, and then a step of hydrodealkylation of the separated heavy effluent, preferably at high temperature, for example at 260-400°C.

[0007] Unpublished patent application FR20 / 01758 describes a method for treating plastic pyrolysis oil, which method comprises: a) selectively hydrogenating said feedstock in the presence of hydrogen and a selective hydrogenation catalyst to obtain a hydrogenated effluent; b) hydrotreating the hydrogenated effluent in the presence of hydrogen and a hydrotreating catalyst to obtain a hydrotreated effluent; c) separating the hydroprocessing effluent in the presence of an aqueous stream at a temperature between 50 and 370°C to obtain a gas effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent; d) optionally fractionating all or a portion of the hydrocarbon-based effluent obtained from step c) to obtain a gas stream and at least two hydrocarbon-based streams, which may be a naphtha fraction and a heavier fraction; e) a recycling step to the selective hydrogenation step a) and / or the hydrotreating step b), comprising a phase for recovering a fraction of the hydrocarbon-based effluent obtained from the separation step c) or one fraction of the hydrocarbon-based effluent obtained from the fractionation step d) and / or at least one of the hydrocarbon-based effluents obtained from the fractionation step d).

[0008] According to patent application FR20 / 01758, the naphtha fraction obtained from the fractionation step may be sent in whole or in part either to a steam cracking unit or to a naphtha pool obtained from conventional petroleum feedstocks, or may be recycled to step e).

[0009] The heavier fractions obtained from the fractionation step may be sent, in whole or in part, either to a steam cracking unit or to the diesel or kerosene pools obtained from conventional petroleum feedstocks, or may be recycled to step e).

[0010] Heavier fractions can be sent to a steam cracking unit, but few refiners prefer this option because they have a high BMCI and contain more naphthenic, naphthenoaromatic, and aromatic compounds relative to the naphtha fraction, thus leading to a higher C / H ratio. This high ratio causes coking in the steam cracker, necessitating a dedicated steam cracking furnace for this fraction.

[0011] Furthermore, steam cracking of such heavy fractions produces notable products, particularly ethylene and propylene, in small amounts, but more predominantly pyrolysis gasoline.

[0012] Therefore, it would be advantageous to minimize the yield of the heavy fraction and maximize the yield of the naphtha fraction by at least partially converting the heavy fraction to a naphtha fraction by hydrocracking in two steps. This allows for obtaining more naphtha, which is preferably sent to steam cracking to produce more olefins, while simultaneously reducing the risk of clogging during the process, particularly in the treatment of plastic pyrolysis oil, such as that described in the prior art, and the risk of coke formation and / or corrosion in large quantities during subsequent process(es), such as the steam cracking process of plastic pyrolysis oil. The heavy fraction not converted in the first hydrocracking process is sent, after separation, to a second hydrocracking process, which is preferably operated at a moderate conversion to maximize selectivity toward naphtha fraction compounds (boiling points below 175°C, particularly 80-175°C). Furthermore, the C2-C4 compounds produced during hydrocracking may be sent to steam cracking, which allows for improved yields of light olefins (ethylene and propylene). Overall, olefin yields are at least maintained or even improved, while at the same time eliminating the need for a dedicated steam cracker for the heavy fraction. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2018 / 055555 Summary of the Invention [Means for solving the problem]

[0014] (Summary of the Invention) The present invention relates to a method for processing a feedstock containing plastic pyrolysis oil, the method comprising: a) a selective hydrogenation step, which is carried out in the presence of at least one selective hydrogenation catalyst in a reaction section to which the gas stream containing the feedstock and hydrogen is fed, wherein the temperature is 100 to 280°C, the hydrogen partial pressure is 1.0 to 10.0 absolute MPa, and the hourly space velocity is 0.3 to 10.0 h -1 to obtain a hydrogenated effluent; b) Hydrotreating step: This step is carried out in a hydrotreating reaction section using at least one fixed bed reactor, the fixed bed reactor containing n catalyst beds, n being an integer equal to or greater than 1, each containing at least one hydrotreating catalyst, and the hydrotreating reaction section is fed with at least the hydrogenated effluent from step a) and a gas stream containing hydrogen, the temperature in the hydrotreating reaction section being 250-430°C, the partial pressure of hydrogen being 1.0-10.0 absolute MPa, and the hourly space velocity being 0.1-10.0 h -1 to obtain a hydrotreated effluent; c) a first hydrocracking step, carried out in a hydrocracking reaction section using at least one fixed bed reactor, the fixed bed reactor containing n catalyst beds, n being an integer greater than or equal to 1, each containing at least one hydrocracking catalyst, to which at least the hydrotreated effluent from step b) and a gas stream containing hydrogen are fed, the hydrocracking reaction section being used at a temperature of 250 to 480°C, a hydrogen partial pressure of 1.5 to 25.0 absolute MPa, and an hourly space velocity of 0.1 to 10.0 h -1 obtaining a first hydrocracked effluent; d) a separation step, wherein the hydrocracked effluent obtained from step c) and an aqueous solution are fed, said step being carried out at a temperature of 50 to 370°C, to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent; e) fractionating all or a portion of the hydrocarbon-based effluent obtained from step d) to obtain at least one gas stream and at least two liquid hydrocarbon-based streams; said liquid hydrocarbon-based streams being at least one naphtha fraction containing compounds having a boiling point less than or equal to 175°C and a hydrocarbon fraction containing compounds having a boiling point greater than 175°C; f) a second hydrocracking step, which is carried out in a hydrocracking reaction section using at least one fixed-bed reactor, which contains n catalyst beds, n being an integer equal to or greater than 1, each containing at least one hydrocracking catalyst, and which is fed to the hydrocracking reaction section with at least a portion of the hydrocarbon fraction obtained from step e) containing compounds having a boiling point above 175°C and a gas stream containing hydrogen, and which is operated at a temperature of 250 to 480°C, a hydrogen partial pressure of 1.5 to 25.0 absolute MPa, and an hourly space velocity of 0.1 to 10.0 h -1 to obtain a second hydrocracked effluent; g) recycling at least a portion of said second hydrocracked effluent obtained from step f) to separation step d).

[0015] One advantage of the process according to the invention is that the oil obtained from the pyrolysis of plastic waste is purified from at least part of its impurities, making it possible to upgrade it by hydrogenating it and therefore making it suitable for treatment in a steam cracking unit, in particular to incorporate it directly into the fuel pool or to obtain in particular improved yields of light olefins that may serve as monomers in the production of polymers.

[0016] Another advantage of the present invention is that it prevents the risk of clogging and / or corrosion of the processing unit in which the method of the present invention is carried out, a risk that is exacerbated by the presence of diolefins, metals and halogenated compounds in plastic pyrolysis oil, often in large amounts.

[0017] Therefore, the method of the present invention makes it possible to obtain a hydrocarbon-based effluent obtained from plastic pyrolysis oil from which the impurities of the starting plastic pyrolysis oil have been at least partially removed, thereby limiting operability problems that these impurities may cause, such as corrosion, coking, or catalyst deactivation, in particular in the steam cracking unit and / or units located downstream of the steam cracking unit, in particular the polymerization and selective hydrogenation units. Removing at least a portion of the impurities from the oil obtained from the pyrolysis of plastic waste also makes it possible to broaden the range of applications of the target polymer, thereby reducing incompatibility of the application.

[0018] The present invention relates to the recycling of plastics by proposing a method for treating oil obtained from the pyrolysis of plastics to purify it, hydrotreat it, and hydrocrack it to obtain a hydrocarbon-based effluent with a reduced content of impurities and therefore directly upgradeable in the form of either naphtha and / or diesel fractions, or with a composition compatible with the feedstock of a steam cracking unit. Hydrocracking makes it possible to convert at least a portion of the heavy fraction (diesel) into naphtha compounds, thereby obtaining an improved yield of naphtha and, if this fraction is sent to steam cracking, an improved yield of light olefins, while at the same time reducing the risk of clogging during the process of treating plastic pyrolysis oil, such as those described in the prior art, and the risk of coke formation and / or corrosion in large quantities encountered during subsequent process(es), for example, during the process of steam cracking of plastic pyrolysis oil.

[0019] According to a variant, the process also comprises a recycling step h) in which the fraction of the hydrocarbon-based effluent obtained from the separation step d) or the fraction of the naphtha cut having a boiling point below 175° C. obtained from the fractionation step e) is sent to a selective hydrogenation step a) and / or a hydrotreating step b).

[0020] According to a variant, the amount of the recycle stream from step h) is adjusted so that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is less than or equal to 10.

[0021] According to a variant, the method comprises a step a0) of pretreating the feedstock comprising plastic pyrolysis oil, said pretreatment step being carried out upstream of the selective hydrogenation step a) and comprising a filtration step and / or a washing step with water and / or an adsorption step.

[0022] According to a variant, the reaction section of step a) or b) employs at least two reactors functioning in a variably arranged manner.

[0023] According to a variant, upstream of step a) a stream containing an amine is injected.

[0024] According to a variant, the selective hydrogenation catalyst comprises a support chosen from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrodehydrogenation functional group 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.

[0025] According to a variant, said at least one hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrodehydrogenation functional group comprising at least one element from group VIII and / or at least one element from group VIB.

[0026] According to a variant, the hydrocracking catalyst comprises a support chosen from halogenated aluminas, combinations of oxides of boron and aluminum, amorphous silica-alumina and zeolites, and a hydrodehydrogenation functional group containing at least one metal of group VIB chosen alone or in mixtures from chromium, molybdenum and tungsten, and / or at least one metal of group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

[0027] According to this variant, said zeolite is chosen from Y zeolites, alone or in combination with other zeolites from among the zeolites Beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 and ZBM-30, alone or as a mixture.

[0028] According to a variant, the naphtha fraction containing compounds with a boiling point below 175°C obtained from step e) is sent in whole or in part to a steam cracking step i), which is carried out in at least one pyrolysis furnace at a temperature of 700-900°C and a pressure of 0.05-0.3 relative MPa.

[0029] According to a variant, the naphtha fraction obtained from step e) containing compounds having a boiling point of 175°C or less is fractionated into a heavy naphtha fraction containing compounds having a boiling point of 80 to 175°C and a light naphtha fraction containing compounds having a boiling point of less than 80°C, and at least a portion of the heavy fraction is sent to an aromatics complex including at least one naphtha reforming step.

[0030] According to this variant, at least part of the light naphtha fraction is sent to the steam cracking step i).

[0031] The present invention also relates to products obtainable via the process according to the invention.

[0032] According to the present invention, unless otherwise indicated, pressures are absolute pressures, also written abs., and are given in absolute MPa (or MPa abs.).

[0033] According to the present invention, the expressions "comprised between ... and ..." and "between A and B or A to B (between ... and ...)" are equivalent and mean that both limits of the interval are included in the range of values ​​stated. If this is not the case and if both limits are not included in the range stated, such clarification is given by the present invention.

[0034] For purposes of the present invention, various ranges of parameters for a given process, such as pressure ranges and temperature ranges, may be used alone or in combination. For example, for purposes of the present invention, a range of preferred pressure values ​​may be combined with a range of more preferred temperature values.

[0035] In the following text, specific and / or preferred embodiments of the present invention may be described, which may be implemented separately or in combination together, without limitation to the combination where this is technically feasible.

[0036] In the following text, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to metals from columns 8, 9 and 10 according to the new IUPAC classification.

[0037] The metal content is measured by X-ray fluorescence. DETAILED DESCRIPTION OF THE INVENTION

[0038] (Detailed explanation) (Feed material) According to the present invention, "plastic pyrolysis oil" refers to an oil obtained from the pyrolysis of plastics, preferably plastic waste, particularly plastic waste from collection and sorting channels, advantageously in liquid form at room temperature. It contains, in particular, a mixture of hydrocarbon-based compounds, particularly paraffins, mono- and / or diolefins, naphthenes, and aromatic compounds, with these hydrocarbon-based compounds preferably having a boiling point of less than 700°C, preferably less than 550°C. Plastic pyrolysis oil may and usually does contain impurities, such as metals, especially silicon and iron, and halogenated compounds, especially chlorinated compounds. These impurities may be present in high concentrations in the plastic pyrolysis oil, for example, up to 350 ppm by weight, or even up to 700 ppm by weight, or even up to 1000 ppm by weight of halogen elements provided by halogenated compounds, and up to 100 ppm by weight, or even up to 200 ppm by weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals, and metalloids can be compared to metallic contaminants called metals, metallic, or semi-metallic elements. In particular, metals, metallic, or semi-metallic elements that may be contained in oil obtained from the pyrolysis of plastic waste include silicon, iron, or both of these elements. Plastic pyrolysis oil may also contain other impurities, such as heteroelements, particularly provided by sulfur compounds, oxygen compounds, and / or nitrogen compounds, in a content of generally less than 10,000 ppm by weight, preferably less than 4,000 ppm by weight of heteroelements.

[0039] The feedstock for the process according to the invention comprises at least one plastic pyrolysis oil. The feedstock may consist solely of plastic pyrolysis oil(s). Preferably, the feedstock comprises at least 50% by weight, preferably 75% to 100% by weight of plastic pyrolysis oil, i.e. preferably 50% to 100% by weight, preferably 70% to 100% by weight of plastic pyrolysis oil. The feedstock for the process according to the invention may, inter alia, comprise one or more plastic pyrolysis oils, conventional petroleum-based feedstocks or feedstocks obtained from the conversion of biomass, which are then co-processed with the feedstock plastic pyrolysis oil.

[0040] Plastic pyrolysis oil can be obtained from thermal catalytic pyrolysis processes or alternatively prepared by hydropyrolysis (thermal cracking in the presence of a catalyst and hydrogen).

[0041] (Preprocessing (optional)) Said feedstock comprising plastic pyrolysis oil may advantageously be pretreated in an optional pretreatment step a0) before the selective hydrogenation step a) to obtain a pretreated feedstock, which is fed to step a).

[0042] This optional pretreatment step a0) makes it possible to reduce the amount of contaminants, particularly silicon, that may be present in the feedstock containing plastic pyrolysis oil. Therefore, the optional step a0) of pretreatment of the feedstock containing plastic pyrolysis oil is advantageously carried out when the feedstock contains more than 50 ppm by weight, particularly 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 the feedstock contains more than 20 ppm by weight of silicon, more particularly more than 10 ppm by weight, or even more particularly more than 5 ppm by weight, or even more particularly more than 1.0 ppm by weight of silicon.

[0043] Said optional pretreatment step a0) may be carried out via any method known to those skilled in the art for reducing the amount of contaminants, which may in particular comprise a filtration step and / or a washing step with water and / or an adsorption step.

[0044] According to one variant, the optional pretreatment step a0) is carried out in an adsorption section operated in the presence of at least one adsorbent. The optional pretreatment step a0) is carried out at a temperature between 0 and 150°C, preferably between 5 and 100°C, and at a pressure between 0.15 and 10.0 MPa absolute, preferably between 0.2 and 1.0 MPa absolute. The adsorption section is advantageously operated in the presence of at least one adsorbent, preferably an alumina-type adsorbent, having a specific surface area of ​​less than 100 m 2 / g or more, preferably 200m 2 The specific surface area of ​​said at least one adsorbent is advantageously greater than or equal to 600 m 2 / g or less, especially 400m 2 The specific surface area of ​​the adsorbent is the surface area measured by the BET method, i.e., the specific surface area determined by nitrogen adsorption according to standard ASTM D 3663-78, which was established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938).

[0045] Advantageously, said adsorbent contains less than 1% by weight of metallic elements, preferably no metallic elements. The term "metallic elements of the adsorbent" should be understood to refer to elements from groups 6 to 10 of the Periodic Table of the Elements (new IUPAC classification).

[0046] The adsorption section of optional step a0) comprises at least one adsorption column, preferably at least two adsorption columns, and preferentially two to four adsorption columns, containing the adsorbent. When the adsorption section comprises two adsorption columns, one operating mode may be what is technically called "swing" operation, in which one column is online, i.e., in service, while the other column is in reserve. When the adsorbent in the online column becomes spent, it is isolated, while the in-reserve column is placed online, i.e., in service. The spent adsorbent can then be regenerated in situ and / or replaced with fresh adsorbent, and the column containing it can be placed online again, where the other column was isolated.

[0047] Another mode of operation is to operate at least two columns in series. When the adsorbent in the top column is spent, this first column is isolated, and the spent adsorbent is either regenerated in situ or replaced with fresh adsorbent. The column is then brought back online at the last position, and so on. This mode of operation is known as a permutable reactor system (PRS) or, alternatively, the specialized term "lead and lag." The combination of at least two adsorption columns makes it possible to overcome the potentially rapid poisoning and / or clogging of the adsorbent due to the combined action of metal contaminants, diolefins, gums derived from diolefins, and insolubles that may be present in the plastic pyrolysis oil being treated. The reason for this is that the presence of at least two adsorption columns allows for easy replacement and / or regeneration of the adsorbent, advantageously without shutting down the pretreatment unit and even the process, thus reducing the risk of clogging and therefore making it possible to avoid shutting down the unit due to clogging, control costs and limit adsorbent consumption.

[0048] Said optional pretreatment step a0) may optionally be fed with a recycle stream, advantageously at least a portion of the recycle stream obtained from step h) of the present process, either in admixture with the feedstock comprising plastic pyrolysis oil or separately therefrom.

[0049] Said optional pretreatment step a0) therefore makes it possible to obtain a pretreated feedstock which is then fed to the selective hydrogenation step a).

[0050] (Selective hydrogenation step a) According to the present invention, the process comprises a step a) of selective hydrogenation of a feedstock containing plastic pyrolysis oil, which is carried out in the presence of hydrogen under conditions of hydrogen pressure and temperature that allow the feedstock to be maintained in the liquid phase, with an amount of soluble hydrogen just necessary for the selective hydrogenation of the diolefins present in the plastic pyrolysis oil. The selective hydrogenation of the diolefins in the liquid phase therefore makes it possible to avoid or at least limit the formation of "gums" that can clog the reaction section of the hydrotreating step b), i.e., the polymerization of diolefins, and therefore the formation of oligomers and polymers. The selective hydrogenation step a) makes it possible to obtain a hydrogenated effluent, i.e., an effluent with a reduced content of olefins, particularly diolefins, and preferably free of diolefins.

[0051] According to the invention, the selective hydrogenation step a) is carried out in a reaction section to which is fed at least the feedstock comprising plastic pyrolysis oil or the pretreated feedstock obtained from optional pretreatment step a0) and a gas stream comprising hydrogen (H2). Optionally, the reaction section of step a) may advantageously be fed at least a portion of a recycle stream obtained from step d) or optional step h), advantageously directly to at least one inlet of a reactor of the reaction section of step a), optionally as a mixture with the pretreated feedstock or optionally separately from the pretreated feedstock. Introduction of at least a portion of the recycle stream into the reaction section of selective hydrogenation step a) advantageously makes it possible to dilute impurities of the optionally pretreated feedstock and, in particular, to control the temperature in the reaction section.

[0052] The reaction section comprises a selective hydrogenation, preferably carried out in a fixed bed in the presence of at least one selective hydrogenation catalyst, at a temperature advantageously between 100 and 280°C, preferably between 120 and 260°C, preferably between 130 and 250°C, and at a hydrogen partial pressure between 1.0 and 10.0 MPa absolute, preferably between 1.5 and 8.0 MPa absolute, and at an hourly space velocity (HSV) between 0.3 and 10.0 h -1 , preferably 0.5 to 5.0 hours -1 The hourly space velocity (HSV) is defined here as the ratio of the hourly volumetric flow rate of the feedstock, optionally comprising pretreated plastic pyrolysis oil, to the volume of catalyst(s). The amount of gas stream comprising hydrogen (H2) fed to said reaction section of step a) is advantageously determined such that the hydrogen coverage is greater than the volume (m2) of the feedstock. 3 ) per 1-200Nm of hydrogen 3 (Nm 3 / m 3 ), preferably the volume of the feedstock (m 3 ) 1 to 50 Nm of hydrogen per 3 (Nm 3 / m 3), preferably the volume of the feedstock (m 3 ) 5 to 20 Nm of hydrogen per 3 (Nm 3 / m 3 The hydrogen coverage is defined as the ratio at 15°C of the volumetric flow rate of hydrogen taken up under standard temperature and pressure conditions relative to the volumetric flow rate of the "fresh" feedstock, i.e., the volumetric flow rate of the feedstock to be treated, possibly pretreated, but without taking into account any recycle fraction (per volume (m 3 ) Nm of H2 per 3 Standard m written as 3 The hydrogen-containing gas stream feeding the reaction section of step a) may consist of feed hydrogen and / or recycled hydrogen obtained in particular from separation step d).

[0053] Advantageously, the reaction section of step a) comprises 1 to 5 reactors. According to a particular embodiment of the present invention, the reaction section comprises 2 to 5 reactors, which are operated in a permutable mode, referred to by the term PRS (permutable reactor system) or the term "lead and lag". Combining at least two reactors in PRS mode makes it possible to isolate one reactor, discharge the spent catalyst, recharge it with fresh catalyst and return said reactor to operation without shutting down the process. PRS technology is described, in particular, in patent FR2681871.

[0054] Advantageously, reactor inserts, for example of the filter plate type, may be used to prevent clogging of the reactor(s). Examples of filter plates are described in patent FR3051375.

[0055] Advantageously, said at least one selective hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrodehydrogenation function.

[0056] According to one variant, the hydrodehydrogenation functional group comprises, in particular, at least one group VIII element and at least one group VIB element, the group VIII element being preferably selected from nickel and cobalt, and the group VIB element being preferably selected from molybdenum and tungsten. According to this variant, the total content of oxides of metallic elements from groups VIB and VIII is preferably between 1% and 40% by weight, preferentially between 5% and 30% by weight, relative to the total weight of the catalyst. The weight ratio, expressed as metal oxides, of the group VIB metal(s) to the group VIII metal(s) is preferably between 1 and 20, preferably between 2 and 10.

[0057] According to this variant, the reaction section of step a) comprises, for example, a selective hydrogenation catalyst comprising 0.5% to 12% by weight of nickel, preferably 1% to 10% by weight of nickel (expressed as nickel oxide, NiO, relative to the weight of the catalyst), and 1% to 30% by weight of molybdenum, preferably 3% to 20% by weight of molybdenum (expressed as molybdenum oxide, MoO, relative to the weight of the catalyst), on a support, preferably a mineral support, preferably an alumina support.

[0058] According to another variant, the hydrodehydrogenation functional group comprises, and preferably consists of, at least one element of 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 the catalyst. This type of catalyst is preferably used in its reduced form on a support, preferably a mineral support, preferably an alumina support.

[0059] The support for the at least one selective hydrogenation catalyst is preferably selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof. The support may contain other dopant compounds, particularly boron oxides, in particular oxides selected from boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide, and mixtures of these oxides. Preferably, the at least one selective hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and optionally boron. If phosphorus pentoxide 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. If 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% by weight relative to the total weight of the alumina. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

[0060] The selective hydrogenation catalyst is, for example, in the form of extrudates.

[0061] Highly preferably, in order to hydrogenate diolefins as selectively as possible, step a) may use, in addition to the selective hydrogenation catalyst described above, at least one selective hydrogenation catalyst used in step a) containing less than 1% by weight of nickel, expressed as nickel oxide NiO relative to the weight of the catalyst, and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, and less than 5% by weight of molybdenum, expressed as molybdenum oxide MoO relative to the weight of the catalyst, and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, on an alumina support. This catalyst with a low metal loading is preferably located upstream of the selective hydrogenation catalyst described above.

[0062] Optionally, the feedstock comprises plastic pyrolysis oil, optionally pretreated and / or optionally premixed with a recycle stream, advantageously at least a portion of the recycle stream obtained from step d) or optional step h), which feedstock may be mixed with a gas stream comprising hydrogen before its introduction into the reaction section.

[0063] Said feedstock may optionally be pretreated and / or optionally mixed with at least part of a recycle stream, advantageously obtained from step d) or optional step h), and / or, possibly as a mixture with a gas stream, this feedstock may be heated, for example by heat exchange, in particular with the hydrotreatment effluent from step b), before being introduced into the reaction section of step a), in order to reach a temperature close to the operating temperature in the reaction section to which it feeds.

[0064] The content of impurities, especially diolefins, of the hydrogenated effluent obtained at the end of step a) is reduced relative to the content of the same impurities, especially diolefins, contained in the feedstock for this process.Selective hydrogenation step a) generally makes it possible to convert at least 90%, preferably at least 99%, of the diolefins contained in the initial feedstock.Step a) also makes it possible to at least partially remove other contaminants, such as silicon.The hydrogenated effluent obtained at the end of selective hydrogenation step a) is preferably sent directly to hydrotreating step b).If at least a portion of the recycle stream obtained from optional step h) is introduced, the hydrogenated effluent obtained at the end of selective hydrogenation step a) therefore comprises, in addition to the converted feedstock, said portion(s) of recycle stream(s).

[0065] (hydrotreatment step b) According to the invention, the treatment process comprises a step b) of hydrotreating, advantageously in a fixed bed, said hydrotreated effluent obtained from step a), optionally in admixture with a recycle stream, advantageously at least a portion of a recycle stream obtained from step d) or optional step h), in the presence of hydrogen and at least one hydrotreating catalyst to obtain a hydrotreated effluent.

[0066] Advantageously, said step b) comprises a hydrotreating reaction well known to those skilled in the art, in particular a hydrogenation reaction of olefins or aromatic compounds, hydrodemetallization, hydrodesulfurization, hydrodenitrification, etc.

[0067] Advantageously, said step b) is carried out in a hydrotreating reaction section, which comprises at least 1, preferably 1 to 5, fixed bed reactors. The fixed bed reactors contain n catalyst beds, n being an integer greater than or equal to 1, preferably between 1 and 10, preferably between 2 and 5. Said bed(s) each contain at least one, and preferably not more than 10, hydrotreating catalysts. When a reactor comprises several catalyst beds, i.e. at least 2, preferably between 2 and 10, preferably between 2 and 5, said catalyst beds are arranged in series in said reactor.

[0068] The hydrotreating reaction section is advantageously fed at least to the first catalyst bed of the first functioning reactor with the hydrogenated effluent obtained from step a) and with a gas stream comprising hydrogen.

[0069] The hydrotreating reaction section of step b) may be fed with a recycle stream, advantageously at least a portion of the recycle stream obtained from step d) or optional step h). The portion(s) of the recycle stream(s) or the entire amount of the recycle stream may be introduced into the hydrotreating reaction section either as a mixture with the hydrogenated effluent obtained from step a) or separately. The portion(s) of the recycle stream(s) or the entire amount of the recycle stream may be introduced into the hydrotreating reaction section into one or more catalyst beds of the hydrotreating reaction section of step b). The introduction of at least a portion of the recycle stream advantageously makes it possible to dilute impurities still present in the hydrogenated effluent and to control the temperature, in particular limit the temperature rise, in the catalyst bed(s) of the hydrotreating reaction section involving a highly exothermic reaction.

[0070] Advantageously, the hydrotreating reaction section is carried out at a pressure equivalent to that used in the reaction section of the selective hydrogenation step a), but at a temperature higher than that of the reaction section of the selective hydrogenation step a). The hydrotreating temperature at which the hydrotreating reaction section is carried out is therefore advantageously between 250 and 430°C, preferably between 280 and 380°C, with a hydrogen partial pressure of 1.0 and 10.0 absolute MPa, and with an hourly space velocity (HSV) of 0.1 and 10.0 h -1 , preferably 0.1 to 5.0 h -1 , preferentially 0.2 to 2.0 hours -1 , preferably 0.2 to 0.8 hours -1 According to the present invention, the "hydrotreating temperature" corresponds to the average temperature in the hydrotreating reaction section of step b). In particular, it corresponds to the weight-average bed temperature (WABT), according to terminology well known to those skilled in the art. The hydrotreating temperature is advantageously determined depending on the catalyst system used, the equipment and its configuration. For example, the hydrotreating temperature (i.e., WABT) is calculated in the following way:

[0071]

number

[0072] In the formula, T inlet : temperature of the hydrogenated effluent at the inlet of the hydrotreating reaction section, T outlet : The temperature of the effluent at the outlet of the hydrotreating reaction section.

[0073] The hourly space velocity (HSV) is defined here as the ratio of the hourly volumetric flow rate of the hydrogenated effluent obtained from step a) per volume of catalyst(s). The hydrogen coverage in step b) is advantageously determined by the volume (m ) of fresh feedstock fed to step a). 3 ) 50-1000Nm of hydrogen per 3 , preferably the volume (m) of fresh feedstock fed to step a) 3 ) 50-500Nm of hydrogen per 3 , preferably the volume (m) of fresh feedstock fed to step a) 3 ) 100-300Nm of hydrogen per 3 The hydrogen coverage is defined here as the ratio of the volumetric flow rate of hydrogen taken under standard temperature and pressure conditions to the volumetric flow rate of the fresh feedstock fed to step a), i.e. the feedstock containing plastic pyrolysis oil or the optionally pretreated feedstock fed to step a) (volume (m ) of fresh feedstock). 3 ) Nm of H2 per 3 Standard m, denoted as 3 The hydrogen may consist of recycled hydrogen, in particular obtained from the feed and / or separation step d).

[0074] Additional gas streams, preferably containing hydrogen, are advantageously introduced at the inlet of each reactor, in particular at the inlet of each reactor operating in series, and / or at the inlet of each catalyst bed from the second catalyst bed of the hydrotreating reaction section. These additional gas streams are also called quench streams. They make it possible to control the temperature in the hydrotreating reactors, where the reactions involved are generally highly exothermic.

[0075] Advantageously, the hydrotreating catalyst used in step b) may be selected from known hydrodemetallization, hydrotreating or silicon capture catalysts, particularly those used for the treatment of petroleum fractions, and combinations thereof. Known hydrodemetallization catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known 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.

[0076] In particular, the hydrotreating catalyst comprises a support, preferably a mineral support, and at least one metallic element having hydrodehydrogenation function. The metallic element having hydrodehydrogenation function advantageously comprises at least one group VIII element and / or at least one group VIB element, the group VIII element being preferably selected from the group consisting of nickel and cobalt, and the group VIB element being preferably selected from the group consisting of molybdenum and tungsten. The total content of oxides of metallic elements from groups VIB and VIII is preferably between 0.1% and 40% by weight, preferentially between 5% and 35% by weight, relative to the total weight of the catalyst. The weight ratio, expressed as metal oxides, between the group VIB metal(s) to the group VIII metal(s) is preferably between 1.0 and 20, preferably between 2.0 and 10. For example, the hydrotreating reaction section of step b) of the method comprises a hydrotreating catalyst comprising 0.5 wt. % to 10 wt. % nickel, expressed as nickel oxide NiO relative to the total weight of the hydrotreating catalyst, preferably 1 wt. % to 8 wt. % nickel, and 1.0 wt. % to 30 wt. % molybdenum, expressed as molybdenum oxide MoO3 relative to the total weight of the hydrotreating catalyst, preferably 3.0 wt. % to 29 wt. % molybdenum, on a mineral support.

[0077] The support for the hydrotreating catalyst is advantageously selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof. The support may contain other dopant compounds, in particular boron oxides, in particular oxides selected from boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide, and mixtures of these oxides. Preferably, the hydrotreating catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron. If present, the concentration of phosphorus pentoxide P2O5 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. If present, the concentration of boron trioxide B2O5 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. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

[0078] The hydrotreating catalyst is, for example, in the form of extrudates.

[0079] Advantageously, the hydrotreating catalyst used in step b) of the process has a specific surface area of ​​250 m 2 / g or more, preferably 300m 2 The specific surface area of ​​the hydrotreating catalyst is advantageously 800 m 2 / g or less, preferably 600m 2 / g or less, especially 400m 2 / g or less. The specific surface area of ​​the hydrotreating catalyst is measured by the BET method, i.e., the specific surface area is determined by nitrogen adsorption according to standard ASTM D 3663-78, which was established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938). Such a specific surface area allows for further improved removal of contaminants, in particular metals such as silicon.

[0080] According to another aspect of the present invention, the hydrotreating catalyst also contains one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such catalysts are often referred to by the term "additivated catalyst." Generally, the organic compounds are compounds containing one or more chemical functional groups selected from carboxylic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional groups, or compounds containing a furan ring, or sugars.

[0081] The hydrotreating step b) advantageously allows for an optimized treatment of the hydrogenated effluent obtained from step a), which in particular allows for the hydrogenation of the unsaturated bonds of the olefinic compounds present in the hydrogenated effluent obtained from step a), the hydrodemetallization of said hydrogenated effluent, and the maximization of the capture of metals, especially silicon, still present in the hydrogenated effluent.The hydrotreating step b) also allows for the hydrodeazotization (HDN) of the hydrogenated effluent, i.e., the conversion of nitrogen species still present in the hydrogenated effluent.Preferably, the nitrogen content of the hydrotreated effluent obtained from step b) is less than or equal to 10 ppm by weight.

[0082] In a preferred embodiment of the invention, the hydrotreating reaction section comprises several fixed bed reactors, preferentially 2 to 5, very preferentially 2 to 4, each containing n catalyst beds, n being an integer greater than or equal to 1, preferably 1 to 10, preferably 2 to 5, advantageously operated in series and / or parallel and / or in variable sequence (or PRS) mode and / or in "swing" mode. The various optional modes of operation, PRS (lead and drag) mode and swing mode, are well known to those skilled in the art and are advantageously as defined below. The advantage of a hydrotreating reaction section comprising several reactors lies in an optimized treatment of the hydrogenated effluent while at the same time reducing the risk of plugging of the catalyst bed(s) and therefore making it possible to avoid unit shutdowns due to plugging.

[0083] According to a highly preferred embodiment of the present invention, the hydrotreating reaction section comprises, and preferably consists of: - (b1) two fixed-bed reactors, operated in swing or variable-sequence mode, preferably in PRS mode, each of the two reactors preferably having a catalyst bed, which advantageously comprises a hydrotreating catalyst, which is preferably chosen from known hydrodemetallization or silicon capture catalysts and combinations thereof; and - (b2) at least one fixed bed reactor, preferably one reactor, located downstream of the two reactors (b1) and advantageously operated in series with the two reactors (b1), said fixed bed reactor (b2) containing 1 to 5 catalyst beds arranged in series, each containing 1 to 10 hydrotreating catalysts, at least one of said hydrotreating catalysts advantageously comprising a support and at least one metallic element, preferably at least one element of group VIII and / or at least one element of group VIB, the latter preferably being selected from nickel and cobalt and the latter preferably being selected from molybdenum and tungsten.

[0084] Optionally, step b) may comprise a heating section located downstream of the hydrotreating reaction section, in which the hydrotreated effluent obtained from step a) is heated to a temperature suitable for hydrotreating, i.e., a temperature between 250 and 430° C. Said optional heating section may therefore comprise one or more exchangers, preferably exchangers allowing heat exchange between the hydrotreated effluent and the hydrotreated effluent, and / or a preheating furnace.

[0085] Advantageously, the hydrotreating step b) allows the complete hydrogenation of the olefins present in the initial feedstock and those obtainable after the selective hydrogenation step a), but also allows at least partial conversion of other impurities present in the feedstock, such as aromatic compounds, metal compounds, sulfur compounds, nitrogen compounds, halogen compounds (especially chlorine compounds) and oxygen compounds. Step b) may also allow further reduction of the contaminant content, such as the metal content and in particular the silicon content.

[0086] (Hydrocracking step c) (first hydrocracking step) According to the invention, the treatment process comprises a first step c) of hydrocracking the hydrotreated effluent obtained from step b) in the presence of hydrogen and at least one hydrocracking catalyst, advantageously in a fixed bed, to obtain a hydrocracked effluent.

[0087] Advantageously, step c) comprises a hydrocracking reaction well known to those skilled in the art, making it possible in particular to convert the heavy compounds contained in the hydrotreated effluent obtained from step b), such as compounds with a boiling point above 175° C., into compounds with a boiling point below 175° C. Other reactions may follow, such as hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrification, etc.

[0088] Advantageously, step c) is carried out in a hydrocracking reaction section comprising at least one, preferably 1 to 5, fixed bed reactors. The fixed bed reactors contain n catalyst beds, n being an integer greater than or equal to 1, preferably 1 to 10, preferably 2 to 5. The bed(s) each comprise at least one, and preferably not more than 10, hydrocracking catalysts. When a reactor comprises several catalyst beds, i.e. at least 2, preferably 2 to 10, preferably 2 to 5, the catalyst beds are arranged in series in the reactor.

[0089] The hydrotreating step b) and the hydrocracking step c) may advantageously be carried out in the same reactor or in different reactors, in which case the reactor comprises several catalyst beds, the first of which comprises the hydrotreating catalyst(s) and the following catalyst beds comprising the hydrocracking catalyst(s).

[0090] The hydrocracking reaction section is advantageously fed at least to the first catalyst bed of the first functioning reactor with the hydrotreated effluent obtained from step b) and with a gas stream comprising hydrogen.

[0091] Advantageously, said hydrocracking reaction section is carried out at a pressure equivalent to that used in the reaction section of the selective hydrogenation step a) or the hydrotreating step b).

[0092] Therefore, the hydrotreating temperature when the hydrocracking reaction section is carried out is advantageously 250 to 480°C, preferably 320 to 450°C, the hydrogen partial pressure is 1.5 to 25.0 absolute MPa, preferably 2 to 20 absolute MPa, and the hourly space velocity (HSV) is 0.1 to 10.0 h -1 , preferably 0.1 to 5.0 h -1 , preferably 0.2 to 4 hours -1According to the present invention, the "hydrocracking temperature" corresponds to the average temperature in the hydrocracking reaction section of each of steps c) and f). In particular, it corresponds to the weight-average bed temperature (WABT), according to terminology well known to those skilled in the art. The hydrocracking temperature is advantageously determined depending on the catalyst system used, the equipment and its configuration. For example, the hydrocracking temperature (or WABT) is calculated in the following way:

[0093]

number

[0094] In the formula, T inlet : temperature of the hydrogenated effluent at the inlet of the hydrocracking reaction section, T outlet : The temperature of the effluent at the outlet of the hydrocracking reaction section.

[0095] The hourly space velocity (HSV) is defined here as the ratio of the hourly volumetric flow rate of the hydrogenated effluent obtained from step a) per volume of catalyst(s). The hydrogen coverage in step c) is advantageously determined by the volume (m ) of fresh feedstock fed to step a). 3 ) 80-2000Nm of hydrogen per 3 , preferably the volume (m) of fresh feedstock fed to step a) 3 ) 200~1800Nm of hydrogen per 3 The hydrogen coverage is defined here as the ratio of the volumetric flow rate of hydrogen utilized under standard temperature and pressure conditions to the volumetric flow rate of the fresh feedstock fed to step a), i.e. the feedstock containing plastic pyrolysis oil, or the optionally pretreated feedstock fed to step a) (volume (m ) of fresh feedstock). 3 ) Nm of H2 per 3 Standard m, denoted as 3 The hydrogen may consist of feed hydrogen and / or recycled hydrogen obtained in particular from separation step d).

[0096] Additional gas streams, preferably containing hydrogen, are advantageously introduced into the inlet of each reactor, in particular into reactors operated in series, and / or into the inlet of each catalyst bed from the second catalyst bed of the hydrocracking reaction section. These additional gas streams are also called quench streams. They also make it possible to control the temperature in the hydrocracking reactor, where the reactions involved are generally highly exothermic.

[0097] In embodiments that make it possible to maximize the production of a naphtha fraction containing compounds with a boiling point of 175°C or less, the operating conditions used in hydrocracking step c) generally make it possible to obtain a conversion per pass of more than 15 wt. %, even more preferably between 20 wt. % and 95 wt. %, to products having at least 80% by volume of product with a boiling point of less than 175°C, preferably less than 160°C, preferably less than 150°C.

[0098] Hydrocracking step c) therefore does not make it possible to convert all compounds having a boiling point above 175° C. into compounds having a boiling point below 175° C. After fractionation step e), a more or less significant proportion of compounds having a boiling point above 175° C. therefore remains, which are sent to a second hydrocracking step f).

[0099] According to the invention, the hydrocracking step c) is carried out in the presence of at least one hydrocracking catalyst.

[0100] The hydrocracking catalyst(s) used in hydrocracking step c) are conventional hydrocracking catalysts known to those skilled in the art and are of the bifunctional type, combining acid functional groups with hydrodehydrogenating functional groups and optionally at least one binder matrix. The acid functional groups have a high surface acidity (typically 150-800 m 2The hydrodehydrogenation functional groups are provided by a support having a surface area of ​​1000 nm / g, such as halogenated (especially chlorinated or fluorinated) alumina, a combination of boron and aluminum oxides, amorphous silica-alumina, and zeolites. The hydrodehydrogenation functional groups are provided by at least one metal from group VIB and / or at least one metal from group VIII of the periodic table.

[0101] Preferably, the hydrocracking catalyst(s) used in step c) comprise a hydrodehydrogenation functional group, which comprises at least one metal from group VIII, selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, preferably from cobalt and nickel. Preferably, the catalyst(s) also comprise at least one metal from group VIB, selected from chromium, molybdenum and tungsten, alone or in a mixture, preferably from molybdenum and tungsten. Hydrodehydrogenation functional groups of the NiMo, NiMoW or NiW type are preferred.

[0102] Preferably, the content of metal from group VIII in the hydrocracking catalyst(s) is advantageously between 0.5% and 15% by weight, preferably between 1% and 10% by weight, percentages expressed as percentages by weight of oxide relative to the total weight of the catalyst.

[0103] Preferably, the content of metal from group VIB in the hydrocracking catalyst(s) is advantageously between 5% and 35% by weight, preferably between 10% and 30% by weight, percentages expressed as percentages by weight of oxide relative to the total weight of the catalyst.

[0104] The hydrocracking catalyst(s) used in step c) may optionally comprise at least one promoter element, which is deposited on the catalyst and is selected from the group formed by phosphorus, boron and silicon. The hydrocracking catalyst(s) optionally comprise at least one element from group VIIA (preferably chlorine and fluorine), optionally at least one element from group VIIB (preferably manganese), and optionally at least one element from group VB (preferably niobium).

[0105] 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 alone or in mixtures from alumina, silica, silica-alumina, aluminates, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide or clay, preferably chosen alone or in mixtures from alumina or silica-alumina.

[0106] Preferably, the silica-alumina contains more than 50% by weight alumina, preferably more than 60% by weight alumina.

[0107] Preferably, the hydrocracking catalyst(s) used in step c) optionally also comprise a zeolite selected from Y zeolites, preferably USY zeolites, alone or in combination with other zeolites from among the Beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 or ZBM-30 zeolites, alone or in mixtures. Preferably, the zeolite is USY zeolite alone.

[0108] When said catalyst comprises a zeolite, the content of zeolite 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 the percentage of zeolite relative to the total weight of the catalyst.

[0109] Suitable catalysts comprise, preferably consist of, at least one metal from Group VIB and optionally at least one non-noble metal from Group VIII, at least one promoter element, preferably phosphorus, at least one Y zeolite and at least one alumina binder.

[0110] Even more preferred catalysts comprise, and preferably consist of, nickel, molybdenum, phosphorus, USY zeolite, and optionally betaolite, and alumina.

[0111] Other suitable catalysts include, and preferably consist of, nickel, tungsten, alumina and silica-alumina.

[0112] Other suitable catalysts include, and preferably consist of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0113] The hydrocracking catalyst is, for example, in the form of extrudates.

[0114] According to another aspect of the present invention, the hydrogenolysis catalyst also contains one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such catalysts are often referred to by the term "additive catalyst." Typically, the organic compounds are selected from compounds containing one or more chemical functional groups selected from carboxylic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional groups, or compounds containing a furan ring, or sugars.

[0115] The preparation of catalysts for steps a), b) or c) is known and generally comprises a step of impregnation of the support with the Group VIII metal and, if present, the Group VIB metal, and optionally phosphorus and / or boron, followed by drying and then optional calcination. In the case of additive catalysts, the preparation is generally carried out by simple drying without calcination after the introduction of the organic compound. The term "calcination" here means a heat treatment at a temperature of 200°C or higher under air or an oxygen-containing gas. Before their use in the process steps, the catalysts are generally subjected to sulfurization to form active species. The catalyst of step a) may also be a catalyst used in its reduced form, and therefore includes a reduction step during its preparation.

[0116] Optionally, step c) may comprise a heating section located downstream of the hydrocracking reaction section, in which the hydrotreated effluent obtained from step b) is heated to a temperature suitable for hydrocracking, i.e., a temperature between 250 and 480° C. Said optional heating section may therefore comprise one or more exchangers, preferably exchangers allowing heat exchange between the hydrotreated effluent and the hydrocracked effluent, and / or a preheating furnace.

[0117] (Separation step d)) According to the invention, the treatment process comprises a separation step d), which is advantageously carried out in at least one washing / separation section, which is fed at least with the hydrocracked effluent obtained from step c) and with an aqueous solution, to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent.

[0118] The gaseous effluent obtained at the end of step d) advantageously comprises hydrogen, preferably at least 90% by volume, preferably at least 95% by volume of hydrogen. Advantageously, said gaseous effluent may be recycled, at least in part, to the selective hydrogenation step a) and / or the hydrotreating step b) and / or the hydrocracking steps c) and f), the recycling system optionally comprising a purification section.

[0119] The aqueous effluent obtained at the end of step d) advantageously contains ammonium salts and / or hydrochloric acid.

[0120] The hydrocarbon-based effluent obtained from step d) comprises hydrocarbon-based compounds and advantageously corresponds to the feedstock plastic pyrolysis oil or biomass co-processed with plastic pyrolysis oil and a fraction of a conventional petroleum-based feedstock or pyrolysis oil, wherein at least a portion of the heavy compounds have been converted to lighter compounds, maximizing the naphtha fraction. The hydrocarbon-based effluent has also been at least partially purified of its impurities, in particular its olefinic (diolefinic and monoolefinic), metallic and halogenated impurities.

[0121] Ammonium chloride salts are formed by reaction of the chloride ions released during step b) by hydrogenation of the chlorinated compounds and subsequently dissolved in water, in particular in the form of HCl, with the ammonium ions generated during step b) by hydrogenation of the nitrogen compounds, in particular in the form of NH3, and / or provided by the injection of the amine and its subsequent dissolution in water. Separation step d) makes it possible to remove these ammonium chloride salts and thus limit the risk of clogging due to their precipitation, in particular in the transfer lines and / or in the sections of the process according to the invention and / or in the transfer lines to the steam cracker. It also makes it possible to remove the hydrochloric acid formed by the reaction of the hydrogen ions with the chloride ions.

[0122] Depending on the content of chlorinated compounds in the initial feedstock to be treated, a stream containing amines, for example monoethanolamine, diethanolamine and / or monodiethanolamine, may be injected upstream of the selective hydrogenation step a), between the selective hydrogenation step a) and the hydrotreating step b) and / or between the hydrocracking step c) and the separation step d), preferably upstream of the selective hydrogenation step a), to ensure a sufficient amount of ammonium ions to combine with the chloride ions formed during the hydrotreating step, thus making it possible to limit the formation of hydrochloric acid and therefore corrosion downstream of the separation section.

[0123] Advantageously, separation step d) comprises the injection of an aqueous solution, preferably water, into the hydrocracked effluent obtained from step c), upstream of the washing / separation section, to at least partially dissolve the ammonium chloride salts and / or hydrochloric acid, thus improving the removal of chlorinated impurities and therefore reducing the risk of clogging caused by the accumulation of ammonium chloride salts.

[0124] The temperature at which separation step d) is carried out is advantageously between 50 and 370° C., preferentially between 100 and 340° C., preferably between 200 and 300° C. Advantageously, separation step d) is carried out at a pressure close to the pressure used in steps a) and / or b) and / or c), preferably between 1.0 and 10.0 MPa, to facilitate the recycling of hydrogen.

[0125] The washing / separation section of step d) may be carried out at least in part in common or separate washing and separation equipment, which is well known (separation vessels, pumps, heat exchangers, washing columns, etc. which may be operated at various pressures and temperatures).

[0126] In any embodiment of the present invention, in addition to or alternatively to the other described embodiments of the present invention, separation step d) comprises the injection of an aqueous solution into the hydrocracked effluent obtained from step c), followed by a washing / separation section, which advantageously comprises separate phases to obtain at least one aqueous effluent loaded with ammonium salts, a washed liquid hydrocarbon-based effluent and a partially washed gaseous effluent. The aqueous effluent loaded with ammonium salts and the washed liquid hydrocarbon-based effluent may then be separated in a decantation vessel to obtain said hydrocarbon-based effluent and said aqueous effluent. The partially washed gaseous effluent may be introduced in parallel into a washing column, where it flows countercurrently against an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrocracked effluent, thereby making it possible to at least partially, preferably completely, remove the hydrochloric acid contained in the partially washed gaseous effluent and thus obtain said gaseous effluent, preferably said gaseous effluent essentially comprising hydrogen, and an acidic aqueous stream. The aqueous effluent obtained from the decanting vessel may optionally be mixed with the acidic water stream and, optionally as a mixture with the acidic water stream, may be used in a water recycle circuit and fed to step d) of separation into the aqueous solution upstream of the washing / separation section and / or the aqueous stream in the wash column. The water recycle circuit may include a supply of water and / or a basic solution and / or a purge to remove dissolved salts.

[0127] In another optional embodiment of the invention, separately or in combination with the other mentioned aspects of the invention, separation step d) may advantageously comprise a "high pressure" washing / separation section, which operates at a pressure close to that of the selective hydrogenation step a) and / or hydrotreating step b) and / or hydrocracking step c), in order to facilitate the recycling of hydrogen. This optional "high pressure" section of step d) may be completed with a "low pressure" section in order to obtain a hydrocarbon-based liquid fraction free of gaseous parts dissolved at high pressure and intended to be processed directly in a steam cracking process or optionally sent to fractionation step e).

[0128] The gas fraction(s) obtained from separation step d) may be subjected to further purification(s) and separation(s) with the aim of recovering at least one hydrogen-rich gas and / or liquid hydrocarbons, in particular ethane, propane and butanes, the hydrogen-rich gases being recycled upstream of steps a) and / or b) and / or c), and the liquid hydrocarbons being advantageously sent, separately or as a mixture, to one or more furnaces of steam cracking step h) in order to increase the overall yield of olefins.

[0129] The hydrocarbon-based effluent obtained from the separation step d) is sent partially or completely, preferably completely, to a fractionation step e).

[0130] (Fractionation step e) The process according to the invention comprises fractionating all or part, preferably all, of the hydrocarbon-based effluent obtained from step d) to obtain at least one gas stream and at least two liquid hydrocarbon-based streams: at least one naphtha fraction containing compounds having a boiling point below 175°C, in particular between 80 and 175°C, and at least one hydrocarbon fraction containing compounds having a boiling point above 175°C.

[0131] Step e) makes it possible in particular to remove gases dissolved in the hydrocarbon-based liquid effluent, such as ammonia, hydrogen sulfide and light hydrocarbons containing 1 to 4 carbon atoms.

[0132] The pressure at which the fractionation step e) is carried out is advantageously less than or equal to 1.0 MPa absolute, preferably between 0.1 and 1.0 MPa absolute.

[0133] According to one embodiment, step e) may be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit comprising a reflux vessel. The stripping column is fed with the hydrocarbon-based liquid effluent obtained from step d) and a steam stream. The hydrocarbon-based liquid effluent obtained from step d) may optionally be heated before entering the stripping column. Thus, the lightest compounds are entrained at the top of the column and conveyed to a reflux circuit comprising a reflux vessel, where gas / liquid separation takes place. The gas phase comprising light hydrocarbons is withdrawn as a gas stream from the reflux vessel. A naphtha fraction comprising compounds with a boiling point of 175° C. or less is advantageously withdrawn from the reflux vessel. A hydrocarbon fraction comprising compounds with a boiling point above 175° C. is advantageously withdrawn at the bottom of the stripping column.

[0134] According to another embodiment, the fractionation step e) may comprise a stripping column followed by a distillation column or a distillation column only.

[0135] The naphtha fraction containing compounds with a boiling point of 175°C or less may be sent in whole or in part to a steam cracking unit, at the outlet of which olefins may be (re)formed to participate in the formation of polymers. It may be sent to a fuel pool, for example a naphtha pool, or alternatively, may be sent in part to the recycling step h).

[0136] A portion of the hydrocarbon fraction comprising compounds with a boiling point above 175° C. is sent at least partly to a second hydrocracking step f).

[0137] According to a preferred embodiment, the naphtha fraction containing compounds with a boiling point below 175°C is sent, in whole or in part, to a steam cracking unit, and the fraction containing compounds with a boiling point above 175°C is sent to hydrocracking step f).

[0138] In another particular embodiment, the optional fractionation step e) may make it possible to obtain, in addition to the gas stream, a naphtha fraction containing compounds with a boiling point of less than or equal to 175°C, preferably between 80 and 175°C, a kerosene fraction containing compounds with a boiling point of more than 175°C and less than 280°C, and finally a diesel fraction containing compounds with a boiling point of more than 280°C and less than 385°C, and a hydrocarbon fraction containing compounds with a boiling point of more than 385°C, known as the heavy hydrocarbon fraction. The naphtha fraction may be sent, in whole or in part, to a steam cracking unit and / or to a naphtha pool obtained from conventional petroleum-based feedstocks; it may be sent to recycling step h); the kerosene fraction and / or diesel fraction may be sent, in whole or in part, to a steam cracking unit or to a kerosene or diesel pool obtained, respectively, from conventional petroleum-based feedstocks, or may be recycled back to the process, like the naphtha fraction; the heavy fraction may, for its part, at least in part, be sent to the second hydrocracking step f).

[0139] In another specific embodiment, the naphtha fraction obtained from step e) containing compounds having a boiling point of 175°C or less is fractionated into a heavy naphtha fraction containing compounds having a boiling point of 80 to 175°C and a light naphtha fraction containing compounds having a boiling point of less than 80°C, and at least a portion of the heavy naphtha fraction is sent to an aromatics complex including at least one naphtha reforming step for producing aromatic compounds. According to this embodiment, at least a portion of the light naphtha fraction is sent to the steam cracking step i) described below.

[0140] The gas fraction(s) obtained from fractionation step e) may be subjected to further purification(s) and separation(s) with the aim of recovering at least light hydrocarbons, in particular ethane, propane and butane, which may advantageously be sent, separately or as a mixture, to one of the furnaces of steam cracking step i) so as to increase the overall yield of olefins.

[0141] (Hydrocracking step f) (second hydrocracking step) According to the invention, the process comprises a second hydrocracking step f) which advantageously comprises cracking, in a fixed bed, at least a portion of the hydrocarbon fraction comprising compounds with a boiling point above 175°C obtained from step e) in the presence of hydrogen and at least one hydrocracking catalyst, so as to obtain a second hydrocracked effluent.

[0142] Advantageously, step f) comprises a hydrocracking reaction well known to those skilled in the art, making it possible, more particularly, to convert at least part of the fraction comprising compounds with a boiling point above 175° C. into compounds with a boiling point below 175° C. Other reactions may follow, such as hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrification, etc.

[0143] Advantageously, step f) is carried out in a hydrocracking reaction section. The hydrocracking reaction section comprises at least one, preferably 1 to 5, fixed bed reactors containing n catalyst beds, n being an integer greater than or equal to 1, preferably 1 to 10, preferably 2 to 5. The bed(s) each contain at least one, and preferably not more than 10, hydrocracking catalysts. When a reactor comprises several catalyst beds, i.e. at least 2, preferably 2 to 10, preferably 2 to 5, the catalyst beds are arranged in series in the reactor.

[0144] The hydrocracking reaction section advantageously feeds at least a portion of the fraction containing compounds with a boiling point above 175°C and a gas stream containing hydrogen to a first catalyst bed of a first functioning reactor.

[0145] Advantageously, said second hydrocracking reaction section is operated at a pressure equivalent to that used in the reaction section of the selective hydrogenation step a) or the hydrotreating step b) or the hydrocracking step c).

[0146] Therefore, the hydrotreating temperature at which the hydrocracking reaction section is operated is advantageously between 250 and 480°C, preferably between 320 and 450°C, the hydrogen partial pressure is between 1.5 and 25.0 absolute MPa, preferably between 3 and 20 absolute MPa, and the hourly space velocity (HSV) is between 0.1 and 10.0 h -1 , preferably 0.1 to 5.0 h -1 , preferably 0.2 to 4 hours -1 The hourly space velocity (HSV) is defined here as the ratio between the hourly volumetric flow rate of the hydrogenated effluent obtained from step a) and the volume of the catalyst(s). The hydrogen coverage in step f) is advantageously determined by the volume (m ) of fresh feedstock fed to step a). 3 ) 80-2000Nm of hydrogen per 3 , preferably the volume (m) of fresh feedstock fed to step a) 3 ) Hydrogen 200~1800Nm 3 The hydrogen coverage is defined here as the ratio of the volumetric flow rate of hydrogen taken under standard temperature and pressure conditions to the volumetric flow rate of the fresh feedstock fed to step a), i.e. the feedstock containing plastic pyrolysis oil, or the feedstock optionally pretreated and fed to step a) (volume (m ) of fresh feedstock). 3 ) Nm of H2 per 3 Standard m, denoted as 3 The hydrogen may consist of recycled hydrogen, in particular obtained from the feed and / or separation step d).

[0147] Additional gas streams, preferably containing hydrogen, are advantageously introduced at the inlet of each reactor, in particular at the inlet of reactors operated in series, and / or at the inlet of each catalyst bed from the second catalyst bed of the hydrocracking reaction section. These additional gas streams are also called quench streams. They make it possible to control the temperature in the hydrocracking reactors, where the reactions involved are generally highly exothermic.

[0148] The operating conditions used in step f) of the process according to the invention generally make it possible to achieve a per-pass conversion of more than 15 wt. %, even more preferably 20 wt. % to 80 wt. %, to a product containing at least 80 vol. % of compounds with a boiling point of 175° C. or less, preferably below 160° C., preferably below 150° C. However, the per-pass conversion in step f) is kept moderate to maximize the selectivity towards naphtha fraction compounds (boiling points of 175° C. or less, in particular 80-175° C.). The per-pass conversion is limited by using a high recycle rate on the loop for the second hydrocracking step. This rate is defined as the ratio between the flow rate of the feed from step f) and the flow rate of the feedstock from step a); preferentially, this ratio is between 0.2 and 4, preferably between 0.5 and 2.5.

[0149] According to the present invention, the hydrocracking step f) is carried out in the presence of at least one hydrocracking catalyst. Preferably, the hydrocracking catalyst for the second step is selected from conventional hydrocracking catalysts known to those skilled in the art, such as those described above for the hydrocracking step c). The hydrocracking catalyst used in step f) may be the same as or different from that used in step c), but is preferably different.

[0150] In one variant, the hydrocracking catalyst used in step f) comprises a hydrodehydrogenation functional group containing at least one noble metal from group VIII chosen from palladium and platinum, alone or in a mixture. The content of noble metal from group VIII is advantageously between 0.01% and 5% by weight, preferably between 0.05% and 3% by weight, the percentages being expressed as percentages by weight of oxide relative to the total weight of the catalyst.

[0151] Optionally, step f) may comprise a heating section located upstream of the hydrocracking reaction section in which the hydrocarbon fraction comprising compounds with a boiling point above 175° C. obtained from step e) is heated to a temperature suitable for hydrocracking, i.e., a temperature between 250 and 480° C. The optional heating section may therefore comprise one or more exchangers and / or a preheating furnace.

[0152] (Step g) of recycling the secondary hydrocracking effluent) According to the invention, the process comprises a step g) of recycling at least a portion, preferably all, of said second hydrocracked effluent obtained from step f) to the separation step d).

[0153] A purge may be installed on the recycle of the second hydrocracked effluent obtained from step f), which, depending on the operating conditions of the process, may be 0-10 wt. % of the hydrocracked effluent obtained from step f) relative to the incoming feedstock, preferably 0.5 wt. % to 5 wt. %.

[0154] (Step h) (optional) of recycling the hydrocarbon-based effluent obtained from step d) and / or the naphtha fraction obtained from step e) having a boiling point of 175°C or less The process according to the invention may comprise a recycle step h), in which part of the hydrocarbon-based effluent obtained from separation step d) or part of the naphtha fraction with a boiling point below 175°C obtained from fractionation step e) is recovered and constitutes a recycle stream. The recycle stream 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 selective hydrogenation step a) and / or the hydrotreating step b). Optionally, part of the recycle stream may be sent to the optional pretreatment step a0). Preferably, the process according to the invention comprises a recycle step h).

[0155] Preferably, at least a portion of the hydrocarbon-based effluent obtained from the separation step d) or the naphtha cut having a boiling point below 175° C. obtained from the fractionation step e) is fed to the hydrotreating step b).

[0156] Advantageously, the amount of the recycle stream is adjusted so that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil, i.e. the feedstock to be treated that feeds the overall process, is less than or equal to 10, preferably less than or equal to 5, and preferentially greater than or equal to 0.001, preferably greater than or equal to 0.01, preferably greater than or equal to 0.1. Highly preferably, the amount of the recycle stream is adjusted so that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is between 0.2 and 5.

[0157] Advantageously, at the start of the process, a hydrocarbon fraction external to the process may be used as a recycle stream. Those skilled in the art will know how to choose said hydrocarbon fraction.

[0158] Recycling a portion of the product obtained to or upstream of at least one of the reaction steps of the process according to the invention advantageously makes it possible, firstly, to dilute impurities and, secondly, to control the temperature during the reaction step(s) involved, in which the reactions may be highly exothermic.

[0159] According to a preferred embodiment of the present invention, the method for treating a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the following steps, preferably in a given order: selective hydrogenation a), hydrotreating b), hydrocracking c), separation d), fractionation e), hydrocracking f) and recycling of the hydrocracked effluent to step d), generating effluents, at least a part of which is suitable for treatment in a steam cracking unit.

[0160] According to another preferred embodiment of the present invention, the method for treating a feedstock comprising plastic pyrolysis oil comprises, preferably consists of, the following steps, preferably in the given order: pretreatment a0), selective hydrogenation a), hydrotreating b), hydrocracking c), separation d), fractionation e), hydrocracking f), and recycling of the hydrocracked effluent to step d), giving rise to an effluent, at least a part of which is suitable for treatment in a steam cracking unit.

[0161] According to a third preferred embodiment of the present invention, a method for treating a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the following steps, preferably in the given order: a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling of the hydrocracked effluent to step d), h) recycling of a portion of the fraction comprising compounds with a boiling point below 175°C into steps a) and / or b), generating an effluent, at least a portion of which is suitable for treatment in a steam cracking unit.

[0162] According to a fourth preferred embodiment of the present invention, a method for treating a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the following steps, preferably in the given order: pretreatment a0), selective hydrogenation a), hydrotreating b), hydrocracking c), separation d), fractionation e), hydrocracking f), and g) recycling the hydrocracked effluent to step d), h) recycling a portion of the fraction comprising compounds with a boiling point below 175°C into steps a) and / or b), generating an effluent, at least a portion of which is suitable for treatment in a steam cracking unit.

[0163] The hydrocarbon-based effluent or the hydrocarbon-based stream(s) thus obtained by treating plastic pyrolysis oil according to the method of the present invention have a composition that is compatible with the specifications of the feedstock entering the steam cracking unit. In particular, the composition of the hydrocarbon-based effluent or the hydrocarbon-based 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, preferentially less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.5 ppm by weight, with: - the content of silicon element (Si) is 1.0 ppm by weight or less, preferably 0.6 ppm by weight or less, and the content of iron element (Fe) is 100 ppb by weight or less; the sulfur content is less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight; the nitrogen content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight, preferably less than or equal to 5 ppm by weight; - the asphaltene content is less than 5.0 ppm by weight; the total content of elemental chlorine is less than or equal to 10 ppm by weight, preferably less than or equal to 1.0 ppm by weight; The content of olefinic compounds (monoolefins and diolefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.1% by weight.

[0164] The content is given as weight percentage (%), parts per million (ppm) or parts per billion (ppb), which is the relative weight concentration relative to the total weight of the stream under consideration.

[0165] The method according to the invention therefore makes it possible to treat plastic pyrolysis oil in order to obtain an effluent which can be injected totally or partly into a steam cracking unit.

[0166] (Steam Cracking Step i) (Optional) The naphtha fraction containing compounds with a boiling point below 175° C. obtained from step e) may be sent in whole or in part to the steam cracking step i).

[0167] Advantageously, the gas fraction(s) obtained from the separation step d) and / or the fractionation step e) containing ethane, propane and butane may be sent, in whole or in part, to the steam cracking step i).

[0168] The steam cracking step i) is advantageously carried out in at least one pyrolysis furnace at temperatures between 700 and 900°C, preferably between 750 and 850°C, and under a pressure of 0.05 to 0.3 relative MPa. The residence time of the hydrocarbon-based compounds is generally less than 1.0 second (denoted s), preferably between 0.1 and 0.5 s. Steam is advantageously introduced upstream of the optional steam cracking step i) after separation (or fractionation). The amount of water introduced, advantageously in the form of steam, is advantageously between 0.3 and 3.0 kg of water per kg of hydrocarbon-based compounds by weight entering step i). Optional step i) is preferably carried out in several parallel pyrolysis furnaces, adapting the operating conditions to the various streams feeding step i), in particular the stream obtained from step e), and managing the decoking time of the tubes. A furnace may contain one or several tubes arranged in parallel. A furnace may also refer to a group of furnaces operating in parallel. For example, a furnace may be dedicated to cracking a naphtha fraction containing compounds with boiling points below 175°C.

[0169] The effluents from the various steam cracking furnaces are generally recombined before separation to form the effluent. It is understood that steam cracking step i) includes not only the steam cracking furnace but also sub-steps related to steam cracking that are well known to those skilled in the art. These sub-steps may include, inter alia, heat exchangers, columns, catalytic reactors, and recycle to the furnace. The columns generally allow fractionation of the effluent in order to recover at least one light fraction containing hydrogen and compounds containing 2 to 5 carbon atoms, a fraction containing pyrolysis gasoline, and optionally a fraction containing pyrolysis oil. The columns allow separation of the various components of the fractionated light fraction to recover at least one fraction rich in ethylene (C2 fraction), a fraction rich in propylene (C3 fraction), and optionally a fraction rich in butenes (C4 fraction). The catalytic reactors particularly allow selective hydrogenation of the C2, C3, and even C4 fractions and pyrolysis gasoline. Saturates, especially those containing 2 to 4 carbon atoms, are advantageously recycled to the steam cracking furnace to improve the overall yield of olefins.

[0170] This steam cracking step i) makes it possible to obtain at least one effluent containing a satisfactory content of olefins containing 2, 3 and / or 4 carbon atoms (i.e. C2, C3 and / or C4 olefins), in particular a content of 30% by weight or more, in particular 40% by weight or more, or even 50% by weight or more of all olefins containing 2, 3 and 4 carbon atoms relative to the weight of the steam cracking effluent under consideration. Said C2, C3 and C4 olefins may advantageously be used as polyolefin monomers.

[0171] According to one or more preferred embodiments of the present invention, individually or in combination, the method for processing a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the above-mentioned sequence of steps, namely: a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling the second hydrocracked effluent to step d), and i) steam cracking, preferably in the given order.

[0172] According to a preferred embodiment, the method for treating a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the above-mentioned sequence of steps, namely pretreatment a0), selective hydrogenation a), hydrotreating b), fractionation c), separation d), fractionation e), hydrocracking f), recycling the second hydrocracked effluent to step d), recycling at least a portion of the naphtha fraction comprising compounds with a boiling point of 175°C or less to steps a) and / or b), and steam cracking step i), preferably in the given order.

[0173] Therefore, the process according to the invention, when it comprises this steam cracking step i), makes it possible to obtain from plastic pyrolysis oil, e.g. plastic waste, olefins that can serve as monomers for the synthesis of new polymers contained in plastics in a relatively satisfactory yield and without clogging or corrosion of the unit.

[0174] (Analysis methods used) The analytical methods and / or specifications used to determine the characteristics of the various streams, in particular the characteristics of the feedstock and effluent to be treated, are known to those skilled in the art and are listed in particular below.

[0175] [Table 1]

[0176] (List of drawings) The information regarding the elements referenced in Figure 1 allows a better understanding of the invention, but the invention is not limited to the specific embodiment shown in Figure 1. The various embodiments presented may be used alone or in combination with each other, without any limitations on combination.

[0177] FIG. 1 represents a scheme of a particular embodiment of the method of the present invention, comprising: - step a) of selective hydrogenation of a hydrocarbon-based feedstock obtained from the pyrolysis of plastics (1); carried out in at least one fixed-bed reactor containing at least one selective hydrogenation catalyst in the presence of a hydrogen-rich gas (2) and any amine provided by stream (3), to obtain an effluent (4); - a step b) of hydrotreating the effluent (4) obtained from step a), carried out in the presence of hydrogen (5) in at least one fixed-bed reactor containing at least one hydrotreating catalyst, to obtain a hydrotreated effluent (6); - a first step c) of hydrocracking of the effluent (6) obtained from step c), carried out in at least one fixed-bed reactor containing at least one hydrocracking catalyst in the presence of hydrogen (7), to obtain a first hydrocracked effluent (8); - step d of separation of the effluent (8); carried out in the presence of an aqueous wash solution (9) to obtain at least one fraction (10) containing hydrogen, an aqueous fraction (11) containing dissolved salts and a hydrocarbon-based liquid fraction (12); - step e) of fractionating the hydrocarbon-based liquid fraction (12); making it possible to obtain at least one gas fraction (13), a naphtha fraction (14) containing compounds with a boiling point below 175°C, and a fraction (15) containing compounds with a boiling point above 175°C; a second step f) of hydrocracking at least a portion (15a) of the fraction containing compounds with a boiling point above 175°C obtained from step e); carried out in at least one fixed-bed reactor containing at least one hydrocracking catalyst in the presence of hydrogen (16), to obtain a second hydrocracked effluent (17); the other part of fraction (15) constitutes a purge (15b); - recycling the second hydrocracked effluent (17) to the separation step d).

[0178] Instead of injecting the amine stream (3) at the inlet of the selective hydrogenation step a), it is possible, depending on the characteristics of the feedstock, to inject it at the inlet of the hydrotreating step b), at the inlet of the hydrocracking step c), at the inlet of the separation step d), or even not at all.

[0179] At the end of step e), at least a portion of the naphtha fraction (14) containing compounds with a boiling point below 175° C. is sent to a steam cracking process (not shown).

[0180] Optionally, part of the naphtha fraction (14) containing compounds with a boiling point below 175° C. obtained from step e) constitutes a recycle stream, which is fed to the selective hydrogenation step a) (fraction (14a)) and to the hydrotreating step b) (fraction (14b)).

[0181] To allow a better understanding of the present invention, only the main steps are shown in Figure 1 along with the main flows. It is clearly understood that all equipment necessary for function (vessels, pumps, heat exchangers, furnaces, columns, etc.) is present even if not shown. It is also understood that a hydrogen-rich gas stream (feed or recycle) may be injected at the inlet of each reactor or catalyst bed, or between two reactors or two catalyst beds, as described above. Means for purifying and recycling hydrogen that are well known to those skilled in the art may be used.

[0182] (Example) (Example 1: Consistent with the present invention) The feedstock (1) treated in this method is plastic pyrolysis oil (i.e., containing 100% by weight of said plastic pyrolysis oil) and has the characteristics shown in Table 2.

[0183] [Table 2]

[0184] (1) The MAV method is described in the following article: C. Lopez-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, pages 57-68

[0185] The feedstock (1) is subjected to a selective hydrogenation step a) which is carried out in a fixed-bed reactor in the presence of hydrogen (2) and an alumina-supported NiMo selective hydrogenation catalyst under the conditions shown in Table 3.

[0186] [Table 3]

[0187] At the end of the selective hydrogenation step a), all of the diolefins originally present in the feedstock have been converted.

[0188] The effluent (4) obtained from the selective hydrogenation step a) is subjected directly, without separation, to the hydrotreating step b), which is carried out in a fixed bed in the presence of hydrogen (5) and an alumina-supported NiMo type hydrotreating catalyst under the conditions shown in Table 4.

[0189] [Table 4]

[0190] The effluent (6) obtained from the hydrotreating step b) is subjected directly, without separation, to a first hydrocracking step c), which is carried out in a fixed bed in the presence of hydrogen (7) and a zeolitic hydrocracking catalyst containing NiMo under the conditions shown in Table 5.

[0191] [Table 5]

[0192] The effluent (8) obtained from the hydrocracking step c) is subjected to a separation step d) according to the invention, in which a stream of water is injected into the effluent obtained from the hydrocracking step c); the mixture is then sent to the separation step d) and treated in a column for washing the acid gases. A gas fraction (10) is obtained at the top of the acid gas washing column, and at the bottom, a two-phase separation vessel makes it possible to separate the aqueous and liquid phases. The gas washing column and the two-phase separator are operated at high pressure. The liquid phase is then sent to a low-pressure vessel in order to recover a second gas fraction and a liquid effluent. This second gas fraction is purged. The liquid effluent (12) obtained at the end of the separation step d) is sent to the fractionation step e). The fractionation step e) comprises a stripping column and a distillation column for the purpose of obtaining a fraction having a boiling point below 175°C (PI-175°C fraction) and a fraction having a boiling point above 175°C (175°C+ fraction).

[0193] The 175° C.+ fraction obtained from fractionation step e) is sent to a second hydrocracking step f) to increase the conversion of compounds boiling above 175° C. A small portion of the 175° C.+ fraction is not sent to the second hydrocracking step f) to avoid the accumulation of polyaromatic compounds that could be coke precursors (purge (15b)).

[0194] The volumetric flow rate of the 175°C+ fraction obtained from fractionation step e) and sent to the second hydrocracking step f) is equal to 80% of the volumetric flow rate of the liquid effluent obtained from hydrotreating step b) and fed to the first hydrocracking step c).

[0195] The second hydrocracking step f) is carried out in a fixed bed in the presence of hydrogen (16) and a zeolitic hydrocracking catalyst containing NiMo under the conditions shown in Table 6.

[0196] [Table 6]

[0197] The effluent (17) obtained from the second hydrocracking step f) is mixed with the effluent (8) from the first hydrocracking step c). The two effluents are subjected to a separation step d) and then a fractionation step e). These two steps, common to both effluents, are carried out as described above.

[0198] Table 7 shows the overall yields for the various fractions obtained at the outlet of the hydrocracking steps c) and f) at the end of the separation step d) and the fractionation step e) (including the stripping column and the distillation column).

[0199] [Table 7]

[0200] The compounds H2S and NH3 are removed mainly in the form of salts in the aqueous phase which is removed in separation step d).

[0201] The treatment of the feedstock according to the process of the invention, in particular through hydrocracking steps c) and f), makes it possible to obtain very high yields of naphtha-type PI-175°C fractions.

[0202] The characteristics of the liquid fractions PI-175°C and 175°C+ obtained after separation step d) and fractionation step e) are given in Table 8.

[0203] [Table 8]

[0204] Both liquid fractions PI-175°C and 175°C+ have compositions that are compatible with steam cracking units because: - they do not contain any olefins (monoolefins and diolefins); - they have very low contents of elemental chlorine (non-detectable content and content of 25 ppb by weight, respectively), below the limit required for steam cracking feedstocks; - the metal content, in particular iron (Fe), is also very low (metal content not detected for the PI-175°C fraction and <1 ppm by weight for the 175°C+ fraction; Fe content not detected for the PI-175°C fraction and 50 ppb by weight for the 175°C+ fraction), which are below the limits required for steam cracking feedstocks (≦5.0 ppm by weight for metals, highly preferably ≦1 ppm by weight; ≦100 ppb by weight for Fe); - Finally, they contain sulfur (<2 ppm by weight for the PI-175°C fraction and <2 ppm by weight for the 175°C+ fraction) and nitrogen (<0.5 ppm by weight for the PI-175°C fraction and <3 ppm by weight for the 175°C+ fraction), with contents much lower than the limits required for steam cracking feedstocks (≦500 ppm by weight, preferably ≦200 ppm by weight for S and N).

[0205] The liquid fraction PI-175°C thus obtained is subsequently sent to the steam cracking step h) (see Table 9).

[0206] [Table 9]

[0207] The effluents from the various steam crackers are subjected to a separation step that allows the recycling of saturates to the steam cracker and the production of the yields shown in Table 10 (yield = % mass of product relative to the mass of the PI-175°C fraction upstream of the steam cracking step, shown as %m / m).

[0208] [Table 10]

[0209] Considering the 93% yield obtained at 175°C+ of the liquid fraction at the outlet of the hydrocracking step during the pyrolysis oil treatment process (see Table 7), it is possible to determine the overall yield of the products obtained from steam cracking step i) relative to the initial feedstock of plastic pyrolysis oil type introduced into step a).

[0210] [Table 11]

[0211] When the PI-175°C fraction is sent to a steam cracking unit, the process according to the invention makes it possible to achieve overall mass yields of ethylene and propylene of 31.9% and 17.4%, respectively, relative to the mass of the initial feedstock of the plastic pyrolysis oil type.

[0212] Furthermore, a particular sequence of steps upstream of the steam cracking step makes it possible to limit coke formation and avoid corrosion problems that would appear if the chlorine were not removed.

[0213] Example 2 (not in accordance with the present invention) In this example, the feedstock to be treated is the same as that described in Example 1 (see Table 2).

[0214] It undergoes the steps of selective hydrogenation a), hydrotreating b) and separation d), carried out under the same conditions as described in Example 1. In this example, which is not in accordance with the invention, the effluent obtained from the hydrotreating step is not subjected to the hydrocracking steps c) and f). The liquid effluent obtained at the end of separation step d) constitutes the PI+ fraction.

[0215] The yields for the various products and the various fractions obtained at the outlet of hydrotreating step b) are given in Table 12 (the yields correspond to the ratio of the mass of the various products obtained relative to the mass of the feedstock upstream of step a), expressed as a percentage and indicated as %m / m).

[0216] [Table 12]

[0217] The characteristics of the PI+ fraction obtained after separation step d) (which corresponds to the liquid effluent) are given in Table 13.

[0218] [Table 13]

[0219] The PI+ fraction obtained via the sequence of steps a), b) and d) consists of about 35% naphtha-type compounds with a boiling point below 175° C. This low yield of naphtha-type compounds with a boiling point below 175° C. is due to the absence of a hydrocracking step in this example, which is not in accordance with the present invention.

[0220] The liquid effluent fraction PI+ is sent directly to the steam cracking step i) under the conditions described in Table 14.

[0221] [Table 14]

[0222] The effluent from the steam cracker is subjected to a separation step that allows for the recycling of saturates to the steam cracker and the production of the yields shown in Table 15 (yield = % mass of product relative to the mass of the PI+ fraction upstream of the steam cracking step, shown as %m / m).

[0223] [Table 15]

[0224] Taking into account the 99.5% yield obtained for the PI+ fraction at the outlet of hydrotreating step b) during the pyrolysis oil treatment process (see Table 12), it is possible to determine the overall yield for the products obtained from steam cracking step i) relative to the initial feedstock of plastic pyrolysis oil type introduced into step a).

[0225] [Table 16]

[0226] When the liquid fraction PI+ is subjected to a steam cracking step, the method according to the invention makes it possible to achieve overall mass yields of ethylene and propylene of 34.6% and 18.9%, respectively, relative to the mass of the initial feedstock of the plastic pyrolysis oil type.

[0227] When the liquid fraction PI+ is subjected to a steam cracking step, the method according to the invention makes it possible to achieve overall mass yields of ethylene and propylene of 34.6% and 18.9%, respectively, relative to the mass of the initial feedstock of the plastic pyrolysis oil type. [Brief explanation of the drawings]

[0228] [Figure 1] 1 depicts a scheme of a particular embodiment of the method of the present invention.

Claims

1. 1. A method for processing a feedstock containing plastic pyrolysis oil, the method comprising: a) a selective hydrogenation step, which comprises feeding the feedstock and a hydrogen-containing gas stream to a reaction section, and carrying out the selective hydrogenation in the presence of at least one selective hydrogenation catalyst, at a temperature of 100 to 280°C, a hydrogen partial pressure of 1.0 to 10.0 MPa absolute, and an hourly space velocity of 0.3 to 10.0 h －１ to obtain a hydrogenated effluent; b) a hydrotreating step carried out in a hydrotreating reaction section using at least one fixed bed reactor containing n catalyst beds, n being an integer greater than or equal to 1, each containing at least one hydrotreating catalyst, to which at least the hydrogenated effluent from step a) and a gas stream containing hydrogen are fed, the temperature in the hydrotreating reaction section being 250 to 430°C, the partial pressure of hydrogen being 1.0 to 10.0 MPa absolute, and the hourly space velocity being 0.1 to 10.0 h －１ to obtain a hydrotreated effluent; c) a first hydrocracking step carried out in a hydrocracking reaction section using at least one fixed bed reactor containing n catalyst beds, n being an integer greater than or equal to 1, each containing at least one hydrocracking catalyst, to which the hydrotreated effluent from step b) and a gas stream containing hydrogen are fed at least, the temperature in the hydrocracking reaction section being 250 to 480°C, the partial pressure of hydrogen being 1.5 to 25.0 MPa absolute, and the hourly space velocity being 0.1 to 10.0 h －１ obtaining a first hydrocracked effluent; d) a separation step, feeding the hydrocracked effluent from step c) and an aqueous solution, said step being carried out at a temperature between 50 and 370°C, to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent; e) fractionating all or a portion of the hydrocarbon-based effluent obtained from step d) to obtain at least one gas stream and at least two liquid hydrocarbon-based streams, said two liquid hydrocarbon-based streams being at least one naphtha fraction containing compounds having a boiling point less than or equal to 175°C and at least one hydrocarbon fraction containing compounds having a boiling point greater than 175°C; f) a second step of hydrocracking, carried out in a hydrocracking reaction section, using at least one fixed bed reactor, which contains n catalyst beds, n being an integer greater than or equal to 1, each containing at least one hydrocracking catalyst, to which at least a portion of the hydrocarbon fraction obtained from step e) containing compounds having a boiling point above 175°C and a gas stream containing hydrogen are fed, the hydrocracking reaction section being operated at a temperature of 250 to 480°C, the partial pressure of hydrogen being 1.5 to 25.0 absolute MPa, and the hourly space velocity being 0.1 to 10.0 h －１ to obtain a second hydrocracked effluent; g) recycling at least a portion of said second hydrocracked effluent obtained from step f) to separation step d).

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

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

4. 4. The method according to claim 1, further comprising a step a0) of pretreating a feedstock comprising plastic pyrolysis oil, said pretreatment step being carried out upstream of the selective hydrogenation step a) and comprising a filtration step and / or a water washing step and / or an adsorption step.

5. 5. The process according to claim 1, wherein the reaction section of step a) or b) employs at least two reactors functioning in a configurationally variable manner.

6. 6. The process according to claim 1, wherein the amine-containing stream is injected upstream of step a).

7. 7. The method according to claim 1, wherein the selective hydrogenation catalyst comprises a support selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof, and a hydrodehydrogenation functional group containing either at least one Group VIII element and at least one Group VIB element, or at least one Group VIII element.

8. 8. The method according to claim 1, wherein the hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrodehydrogenation functional group comprising at least one Group VIII element and / or at least one Group VIB element.

9. 9. The method according to claim 1, wherein the hydrocracking catalyst in step c) or step f) comprises a support selected from halogenated alumina, a combination of boron and aluminum oxides, amorphous silica-alumina, and zeolite, and a hydrodehydrogenation functional group containing at least one Group VIB metal selected from chromium, molybdenum, and tungsten, either alone or in admixture, and / or at least one Group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, and platinum.

10. 10. The process of claim 9, wherein the zeolite is selected from Y zeolites, alone or in combination with other zeolites from among Beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 and ZBM-30 zeolites, alone or as mixtures.

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

12. The method according to any one of claims 1 to 11, wherein the naphtha fraction obtained from step e) and containing compounds having a boiling point of 175°C or less is fractionated into a heavy naphtha fraction containing compounds having a boiling point of 80 to 175°C and a light naphtha fraction containing compounds having a boiling point of less than 80°C, and at least a portion of the heavy naphtha fraction is sent to an aromatics complex including at least one naphtha reforming step.

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

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