PROCESS FOR TREATMENT OF PLASTICS PYROLYSIS OIL INCLUDING AN H2S RECYCLING STEP

Abstract

The present invention relates to a process for treating a plastic pyrolysis oil, comprising: - hydrotreating the feedstock in the presence of hydrogen and a catalyst; - separating / washing the hydrotreated effluent in the presence of an aqueous solution to obtain at least a first aqueous effluent and a hydrotreated hydrocarbon effluent; - separating the H2S contained in the first aqueous effluent to obtain a gaseous phase containing H2S and a second aqueous effluent, said gaseous phase containing H2S being at least partially recycled upstream of step b); - separating the NH3 contained in the second aqueous effluent to obtain a gaseous phase containing NH3 and a third aqueous effluent. The present invention, through the recycling of the H2S from the process, reduces the consumption of sulfurizing agents required to maintain the catalysts in sulfide form in feedstocks containing only a small amount of sulfur.

Description

Title of the invention: METHOD FOR TREATMENT OF PLASTICS PYROLYSIS OIL INCLUDING AN H2S RECYCLING STEP technical field

[0001] The present invention relates to a process for treating a plastic pyrolysis oil to obtain a hydrocarbon effluent that can be used in a gasoline, jet fuel, or diesel fuel storage unit or as feedstock for a steam cracking unit. More particularly, the present invention relates to a process for treating a feedstock from the pyrolysis of plastic waste, enabling the recycling of a gaseous phase containing H2S from the process in order to maintain the catalysts in sulfide form during the catalytic steps of the process and thus reduce the consumption of added sulfurating agent. Previous technique

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

[0003] Another way to valorize plastic pyrolysis oils is by using these oils as feedstock in a steam cracking unit to (re)create olefins, which are monomers that constitute certain polymers. However, plastic waste is generally a mixture of several polymers, for example, mixtures of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polystyrene. Furthermore, depending on their use, plastics may contain, in addition to polymers, other compounds such as plasticizers, pigments, dyes, or residues of polymerization catalysts. Plastic waste may also contain, in small quantities, biomass from, for example, household waste.Waste treatment, including storage, mechanical processing, sorting, pyrolysis, and the storage and transport of pyrolysis oil, can also induce corrosion. As a result, oils from the pyrolysis of plastic waste contain many impurities, particularly diolefins, metals (especially iron and silicon), halogenated compounds (especially chlorine-based compounds), heteroelements such as sulfur, oxygen, and nitrogen, and insolubles, often at high levels incompatible with steam cracking units or downstream units. Steam cracking, particularly polymerization and selective hydrogenation processes, can be affected by these impurities. These impurities can lead to operability problems, including corrosion, coking, catalytic deactivation, and incompatibility issues with the target polymers. The presence of diolefins can also cause pyrolysis oil instability, characterized by gum formation. Gums and insolubles present in the pyrolysis oil can lead to clogging problems in the processes.

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

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

[0006] Unpublished patent application FR 21 / 00.026 describes a process for treating a plastics pyrolysis oil aimed at reducing and / or eliminating impurities contained in the pyrolysis oil in order to obtain an effluent compatible with a steam cracker. The process comprises the following steps:

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

[0008] One way to eliminate impurities contained in explastic pyrolysis oils is to carry out hydrotreatment in the presence of catalysts which are active in sulfide form.

[0009] In the context of feedstocks containing plastic pyrolysis oil, the feedstocks are generally quite low in sulfur. However, a minimum ppH2S is necessary in the hydrotreating reactor to maintain the catalysts in sulfide form and thus prevent their reduction. To maintain a sufficient ppH2S in the reactor, and given that the feedstocks do not contain enough sulfur, a sulfurizing agent is generally, or even necessarily, added continuously, typically DMDS (dimethyl disulfide) to the feedstock. The sulfurizing agent decomposes very rapidly into H2S through the action of temperature and hydrogen at the reactor inlet and therefore provides the quantity of H2S necessary to ensure a minimum and sufficient ppH2S.

[0010] After hydrotreatment, at least some of the H2S contained in the effluent forms Ammonium sulfide ((NH4)2S) salts are present along with NH3 generated by the hydrogenation of nitrogen compounds during hydrotreating. Unlike conventional fossil-based feedstocks, ex-plastic pyrolysis oils generally contain higher levels of nitrogen than sulfur. These salts are typically removed by water scrubbing, followed by a single steam stripping step of the aqueous effluent. This results in a purified aqueous effluent and a gaseous phase containing H2S and NH3, which are generally discharged together at the top of the stripping column. The gaseous phase containing H2S and NH3 is then typically burned to produce SOX (sulfur oxides) and N2 or NOX (nitrogen oxides).

[0011] The gaseous phase containing H2S and NH3 could be recovered and returned to the inlet of the hydrotreating unit to maintain the ppH2S in the reactor without adding a sulfuric agent. However, the NH3 contained in this gaseous phase prevents this, as the resulting NH3 concentration in the recycling loop would be detrimental to the unit's operation. Furthermore, the presence of NH3 lowers the ppH2. Therefore, the gaseous phase containing H2S and NH3 cannot be directly reused as a source of H2S to maintain the catalysts in sulfide form.

[0012] The present invention proposes a process for treating a feed comprising a plastic pyrolysis oil, enabling the recycling of a phase containing only H2S for use as an H2S source at the input of the catalytic units of the process. This is achieved by performing a separation, generally by stripping, in two stages, allowing the H2S to be separated from the NH3. Indeed, the use of two stripping columns operating under different conditions makes it possible to separate the H2S from the NH3 and thus recover:

[0013] - a gaseous phase containing H2S which can be recycled at the unit inlet hydrotreatment;

[0014] - and a gaseous phase containing NH3 which can be burned or also be recycled at the input of the hydrotreatment unit;

[0015] The two-step stripping process for separating H2S from NH3 thus offers the following advantages:

[0016] - The elimination of NH3 in the phase containing only H2S allows the recycling of H2S at the inlet of the catalytic units of the process;

[0017] - A significant minimization of the consumption of sulfurating agent;

[0018] - Eliminating the gaseous phase containing NH3 by burning it is easier because it no longer contains H2S which forms SOx-type pollutants;

[0019] - The gaseous phase containing NH3 can also be recycled at the inlet of catalytic units, advantageously in stoichiometric quantities adapted to the formation of salts during step c) of separation / washing;

[0020] - Improved compliance with environmental constraints regarding SOx because the the majority of H2S is not burned (but on the contrary recycled in a loop);

[0021] - A decrease in hydrogen consumption in the hydrotreating unit because The sulfurizing agent (DMDS) consumes hydrogen to decompose;

[0022] - Total elimination of NH3 in the gaseous effluent containing hydrogen and / or light hydrocarbons from the head of the separation / washing section (step c) described below). Indeed, the NH3 was captured as ammonium sulfide in the aqueous effluent by the excess H2S, which was then recycled. The gaseous effluent, thus free of NH3, can then be sent to a steam cracker to increase the overall olefin yield. Summary of the invention

[0023] More specifically, the invention relates to a process for treating a feed comprising a plastic pyrolysis oil, comprising:

[0024] a) optionally a hydrogenation step implemented in a hydrogenation reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at less a hydrogenation catalyst, said hydrogenation reaction section being fed at least by said feedstock and a gaseous stream comprising hydrogen, said hydrogenation reaction section being operated at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a hydrogenated effluent,

[0025] b) a hydrotreating step carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst, said hydrotreating reaction section being fed at least by the feed or said hydrogenated effluent from step a) and a gas stream comprising hydrogen, said hydrotreating reaction section being carried out at an average temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a hydrotreated effluent,

[0026] c) a separation step, fed by the hydrotreated effluent from step b) and possibly by the hydrocracked effluent from step g) and an aqueous solution to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent,

[0027] d) a step of separating the H2S contained in the first aqueous effluent to obtain a gaseous phase containing the H2S and a second aqueous effluent, said gaseous phase containing the H2S is optionally at least partly recycled upstream of step a) and / or step b) and / or step g),

[0028] e) a step of separating the NH3 contained in the second aqueous effluent to obtain a gaseous phase containing NH3 and a third aqueous effluent, said gaseous phase containing NH3 is optionally at least partly recycled upstream of step a) and / or step b) and / or step g),

[0029] f) optionally a fractionation step of all or part of the hydrocarbon effluent from step c), to obtain at least one gaseous effluent and at least one first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C,

[0030] (g) optionally a hydrocracking step carried out in a hydrocracking reaction section, employing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed by at least a portion of said hydrocarbon effluent from step (c) and / or by at least a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C from step (f) and a flux gaseous comprising hydrogen, said hydrocracking reaction section being implemented at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric rate between 0.1 and 10.0 h 1 to obtain a first hydrocraced effluent.

[0031] The present invention therefore relates to a process for purifying oil obtained from the pyrolysis of plastic waste by removing at least some of its impurities, thus enabling its hydrogenation and allowing its valorization, in particular by directly incorporating it into the fuel storage unit or by making it compatible with treatment in a steam cracking unit, while also allowing for the continuous recycling of the H2S produced by the process in order to minimize the consumption of sulfurizing agent. The injection of a sulfurizing agent remains necessary, notably at the beginning of the catalytic cycle, while the H2S is formed to be separated in step d) and recycled upstream of step a) and / or step b) and / or step g), and / or upstream of the selective hydrogenation step a0). Additional injections throughout the catalytic cycle may be necessary to compensate for natural losses.However, the ability to recycle a gaseous phase containing H2S without NH3 by the present invention makes it possible to considerably reduce the consumption of the sulfurizing agent.

[0032] Another advantage is the removal of NH3 from the gaseous effluent containing hydrogen and / or light hydrocarbons from the head of the separation / washing section (step c) by reaction with the excess H2S recycled as ammonium sulfide in the aqueous effluent. In other words, the NH3 is released as a salt into the aqueous effluent.

[0033] Another advantage of the invention is to prevent the risks of clogging and / or corrosion of the processing unit in which the process of the invention is implemented, the risks being exacerbated by the presence, often in large quantities, of diolefins, metals and halogenated compounds in the pyrolysis oil of plastics.

[0034] The process of the invention thus makes it possible to obtain a hydrocarbon effluent from a plastic pyrolysis oil that is at least partially free of impurities from the starting plastic pyrolysis oil, thereby limiting operability problems, such as corrosion, coking, or catalytic deactivation, that these impurities can cause, particularly in steam cracking units and / or in units located downstream of steam cracking units, notably polymerization and hydrogenation units. The elimination of at least some of the impurities from the oils resulting from the pyrolysis of plastic waste will also increase the range of applications for the target polymers, as incompatibilities in use are reduced.

[0035] According to one variant, said gaseous phase containing H2S from step d) is at less partly recycled upstream of step a) and / or step b) and / or step g).

[0036] According to one variant, the process includes the hydrogenation step a).

[0037] According to one variant, the process includes the fractionation step f).

[0038] According to one variant, the process includes the hydrocracking step g).

[0039] According to one variant, step d) of separating the H2S contained in the first effluent aqueous is carried out by stripping said effluent with a stream containing water vapor at a pressure between 0.5 and 1 MPa and a temperature between 80 and 150°C.

[0040] According to one variant, step e) of separating the NH3 contained in the second aqueous effluent is carried out by stripping said effluent with a flow containing water vapor at a pressure between 0.1 and 0.5 MPa and a temperature between 80 and 150°C.

[0041] According to one variant, the separation step c) comprises the following steps:

[0042] c) a separation step, fed by the hydrotreated effluent from step b), said step being operated at a temperature between 200 and 450°C and at a pressure substantially identical to the pressure of step b) to obtain at least one gaseous effluent and one liquid effluent, part of which is possibly recycled upstream of step a) and / or step b), c2) a separation step, fed by the gaseous effluent from step cl) and another part of the liquid effluent from step cl) and an aqueous solution, said step being carried out at a temperature between 20 and below 200°C, and at a pressure substantially the same as or below the pressure of step b), to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent.

[0043] According to one variant, the process comprises at least one pretreatment step aO) of the feed comprising a plastics pyrolysis oil, optionally mixed with the hydrocarbon effluent from step c), said pretreatment step being carried out upstream of step a) and / or upstream of step b) and comprises a filtration step and / or a centrifugation step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step and / or a selective hydrogenation step.

[0044] According to one variant, the hydrocarbon effluent from the separation step c), or at least one of the two liquid hydrocarbon cuts from step f), is sent in whole or in part to a steam cracking step h) carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C and at a pressure between 0.05 and 0.3 MPa relative.

[0045] According to one variant, said gaseous phase containing NH3 from step e) is at least partly recycled upstream of step a) and / or step b) and / or step g).

[0046] According to one variant, a stream containing a nitrogen compound and / or a sulfur compound is injected upstream of step a) and / or upstream of step b).

[0047] According to one variant, said hydrogenation catalyst comprises a support selected from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof and a hydro-dehydrogenating function comprising either at least one element from group VIII and at least one element from group VIB, or at least one element from group VIII.

[0048] According to one variant, said hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof, and a hydro-dehydrogenating function comprising at least one element from group VIII and / or at least one element from group VIB.

[0049] According to one variant, the process further comprises a second hydrocracking step g') carried out in a hydrocracking reaction section, employing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed by at least a part of the first hydrocracking effluent from the first hydrocracking step g) and a gas stream comprising hydrogen, said hydrocracking reaction section being carried out at a temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a second hydrocracking effluent.

[0050] According to one variant, said hydrocracking catalyst comprises a support selected from halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites and a hydro-dehydrogenating function comprising at least one metal from group VIB selected from chromium, molybdenum and tungsten, alone or in mixture, and / or at least one metal from group VIII selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

[0051] The invention also relates to the product that can be obtained, and preferably obtained by the process according to the invention.

[0052] According to this variant, the product comprises, in relation to the total weight of the product: - a total content of metallic elements less than or equal to 10.0 ppm by weight, - of which an iron content less than or equal to 200 ppb by weight, and / or - a silicon content less than or equal to 5.0 ppm by weight, and / or - a sulfur content less than or equal to 100 ppm by weight, and / or - a nitrogen content less than or equal to 100 ppm by weight, and / or - a chlorine content less than or equal to 10 ppm by weight, and / or - a mercury content less than or equal to 5 ppb by weight.

[0053] According to the present invention, the pressures are absolute pressures, also noted abs., and are given in absolute MPa (or abs. MPa), unless otherwise indicated.

[0054] According to the present invention, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this were not the case and the limit values ​​were not included in the range described, such clarification will be provided by the present invention.

[0055] In the sense of the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the sense of the present invention, a range of preferred pressure values ​​can be combined with a range of more preferred temperature values.

[0056] In the following, particular and / or preferred embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation of combination where technically feasible.

[0057] In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII (or VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IUP AC classification.

[0058] The metal content is measured by X-ray fluorescence. DETAILED DESCRIPTION The charge

[0059] According to the invention, a "plastic pyrolysis oil" is an oil, advantageously in liquid form at room temperature, obtained from the pyrolysis of plastics, preferably plastic waste originating in particular from collection and sorting channels. It can also be obtained from the pyrolysis of used tires.

[0060] It comprises in particular a mixture of hydrocarbon compounds, notably paraffins, mono- and / or di-olefins, naphthenes, and aromatics. At least 80% by weight of these hydrocarbon compounds preferably have a boiling point below 700°C, and preferably below 550°C. In particular, depending on the origin of the pyrolysis oil, it may comprise up to 70% by weight of paraffins, up to 90% by weight of olefins, and up to 90% by weight of aromatics, it being understood that the sum of the paraffins, olefins, and aromatics is 100% by weight of the hydrocarbon compounds.

[0061] The density of the pyrolysis oil, measured at 15°C according to the ASTM D4052 method, is generally between 0.75 and 0.99 g / cm3, preferably between 0.75 and 0.95 g / cm3.

[0062] The pyrolysis oil of plastics may include, and most often includes, in In addition to impurities such as metals, particularly iron and silicon, and halogenated compounds, including chlorinated compounds, these impurities can be present in plastic pyrolysis oil at high levels, for example, up to 350 ppm by weight, or even 700 ppm by weight or 1000 ppm by weight of halogenated elements (particularly chlorine) from halogenated compounds, and up to 100 ppm by weight or even 200 ppm by weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals, and metalloids can be considered contaminants of a metallic nature, referred to as metallic or semi-metallic metals or elements. Specifically, the metals or metallic or semi-metallic elements that may be present in oils from the pyrolysis of plastic waste include silicon, iron, or both.Plastic pyrolysis oil may also include other impurities such as heteroelements supplied in particular by sulfur compounds, oxygenated compounds and / or nitrogenous compounds, at levels generally less than 27000 ppm weight of heteroelements and preferably less than . 15,500 ppm by weight of heteroatoms. Sulfur compounds are generally present at a concentration of less than 2,000 ppm by weight and preferably less than 500 ppm by weight. Oxygen compounds are generally present at a concentration of less than 15,000 ppm by weight and preferably less than 10,000 ppm by weight. Nitrogen compounds are generally present at a concentration of less than 10,000 ppm by weight and preferably less than 5,000 ppm by weight. The pyrolysis oil of plastics may also contain other impurities such as heavy metals like mercury, arsenic, zinc, and lead, for example, up to 100 ppb by weight or even 200 ppb by weight of mercury.

[0063] The feed for the process according to the invention comprises at least one plastic pyrolysis oil. Said feed may consist solely of plastic pyrolysis oil(s). Preferably, said feed comprises at least 50% by weight, preferably between 70% and 100% by weight, of plastic pyrolysis oil relative to the total weight of the feed, i.e. preferably between 50% and 100% by weight, preferably between 70% and 100% by weight of plastic pyrolysis oil.

[0064] The feed of the process according to the invention may include, in addition to the plastic pyrolysis oil or oils, a conventional petroleum feed or a feed from biomass conversion which is then co-treated with the plastic pyrolysis oil of the feed.

[0065] The conventional petroleum feedstock can advantageously be a cut or a mixture of cuts of the naphtha, diesel or vacuum diesel type.

[0066] The feedstock resulting from biomass conversion can advantageously be chosen from vegetable oils, algae or algal oils, fish oils, Used cooking oils and fats of vegetable or animal origin; or mixtures of such fillers. These vegetable oils may advantageously be crude or refined, wholly or partially, and derived from plants selected from rapeseed, sunflower, soybean, palm, olive, coconut, copra, castor, cottonseed, peanut, linseed, and crambe oils, and all oils derived, for example, from sunflower or rapeseed by genetic modification or hybridization, this list not being exhaustive. These animal fats are advantageously selected from lard and fats composed of residues from the food industry or from the catering industry. Frying oils, various animal oils such as fish oil, tallow, and lard may also be used.The feedstock from biomass conversion can also advantageously be chosen from methyl esters of fatty acids of vegetable and / or animal origin, or from methyl esters of fatty acids from used edible vegetable oils.

[0067] The feedstock resulting from biomass conversion can also be selected from feedstocks obtained from thermal or catalytic biomass conversion processes, such as oils produced from biomass, particularly lignocellulosic biomass, using various liquefaction methods, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to material derived from recently living organisms, including plants, animals, and their by-products. The term "lignocellulosic biomass" refers to biomass derived from plants or their by-products. Lignocellulosic biomass is composed of carbohydrate polymers (cellulose, hemicellulose) and an aromatic polymer (lignin).

[0068] The feed from biomass conversion can also advantageously be chosen from feeds from the paper industry.

[0069] Plastic pyrolysis oil can be obtained from a thermal pyrolysis treatment, catalytic or can be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen). Preprocessing (optional)

[0070] Said feed comprising a plastics pyrolysis oil, optionally mixed with the hydrocarbon effluent from step c) can advantageously be pretreated in at least one optional pretreatment step aO), prior to step a) of hydrogenation and / or step b) of hydrotreatment, to obtain a pretreated feed which feeds step a) and / or step b).

[0071] According to one embodiment, this optional pretreatment step aO) makes it possible to reduce the quantity of contaminants and solid particles, in particular the quantity of iron and / or silicon and / or chlorine, possibly present in the feed containing a plastic pyrolysis oil. This optional step aO) notably allows The removal of sediments that may form due to the instability of pyrolysis oils and / or a compatibility issue between two different feedstocks. Thus, an optional pretreatment step (aO) of the feedstock containing a plastic pyrolysis oil is advantageously carried out, particularly when said feedstock contains more than 10 ppm by weight, especially more than 20 ppm by weight, and more particularly more than 50 ppm by weight, of metallic elements and / or solid particles, and particularly when said feedstock contains more than 5 ppm by weight of silicon, especially more than 10 ppm by weight, or even more than 20 ppm by weight of silicon. Similarly, an optional pretreatment step (aO) of the feedstock containing a plastic pyrolysis oil is advantageously carried out, particularly when said feedstock contains more than 10 ppm by weight, especially more than 20 ppm by weight, and more particularly more than 50 ppm by weight of chlorine.

[0072] Said optional pretreatment step aO) can be implemented by any method known to those skilled in the art that reduces the amount of contaminants. It may in particular include a filtration step and / or a centrifugation step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step and / or a selective hydrogenation step.

[0073] When the optional pretreatment step aO) includes a filtration step and / or a centrifugation step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step, it is advantageously carried out at a temperature between 20 and 400°C, preferably between 40 and 350°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 7.0 MPa abs.

[0074] According to one variant, said optional pretreatment step aO) is carried out in an adsorption section operated in the presence of at least one adsorbent, preferably of the alumina type, having a specific surface area greater than or equal to 100 m² / g, preferably greater than or equal to 200 m² / g. The specific surface area of ​​said at least adsorbent is advantageously less than or equal to 600 m² / g, in particular less than or equal to 400 m² / g. The specific surface area of ​​the adsorbent is a surface area measured by the BET method, that is to say, the specific surface area determined by nitrogen adsorption in accordance with ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938).

[0075] Advantageously, said adsorbent comprises less than 1% by weight of metallic elements, preferably is free of metallic elements. By metallic elements of the adsorbent, we mean the elements of groups 6 to 10 of the periodic table of elements (new IUP AC classification). The residence time of the charge in the The adsorption period is generally between 1 and 180 minutes.

[0076] Said adsorption section of optional step aO) comprises at least one adsorption column, preferably comprising at least two adsorption columns, preferably between two and four adsorption columns, containing said adsorbent. When the adsorption section comprises two adsorption columns, one operating mode may be a so-called "swing" operation, in which one of the columns is online, i.e., in operation, while the other column is in reserve. When the adsorbent in the online column is depleted, that column is isolated while the reserve column is brought online, i.e., into operation. The depleted adsorbent can then be regenerated in situ and / or replaced with fresh adsorbent so that the column containing it can be brought online again once the other column has been isolated.

[0077] Another operating mode involves having at least two columns operating in series. When the absorbent in the leading column is depleted, this first column is isolated, and the spent absorbent is either regenerated in situ or replaced with fresh absorbent. The column is then placed back in the last position, and so on. This operation is called the permutable mode, or, in English, "PRS" for Permutable Reactor System, or "lead and lag" in the established English term. Combining at least two adsorption columns makes it possible to mitigate the potential and potentially rapid poisoning and / or clogging of the adsorbent due to the combined action of metallic contaminants, diolefins, gums derived from diolefins, and insolubles that may be present in the pyrolysis oil of the plastics being treated.The presence of at least two adsorption columns facilitates the replacement and / or regeneration of the adsorbent, advantageously without stopping the pretreatment unit, or even the process, thus reducing the risk of clogging and therefore avoiding unit shutdown due to clogging, controlling costs and limiting adsorbent consumption.

[0078] According to another embodiment, said optional pretreatment step aO) is carried out in a washing section with an aqueous solution, for example water or an acidic or basic solution. This washing section may include equipment for contacting the feed with the aqueous solution and separating the phases so as to obtain the pretreated feed on the one hand and the aqueous solution containing impurities on the other. This equipment may include, for example, a stirred reactor, a decanter, a mixer-decanter, and / or a co-current or counter-current washing column.

[0079] According to another embodiment, said optional pretreatment step aO) is carried out by filtration. The filtration step makes it possible to remove inorganic solids, Sediments and / or fines contained in the feed, including metals, metal oxides, and metal chlorides, are typically removed. A filter with a pore size (e.g., diameter or equivalent diameter) of less than 25 µm is generally used, preferably less than or equal to 10 µm, and even more preferably less than or equal to 5 µm. Alternatively, a filter with a pore size less than 25 µm but greater than 5 µm may be used. A series of filters with different pore sizes may also be used, including a series of filters with decreasing pore sizes in the direction of feed flow. These filter media are well-known for industrial applications. Cartridge filters and self-cleaning filters are suitable examples. The dry extract can be measured, for example, by the Heptane Insolubles test, ASTM D-3279 method.The content of insolubles in heptane must be reduced to less than 0.5% by weight, preferably less than 0.1%.

[0080] According to a particular embodiment, the pretreatment step aO) by filtration comprises at least one filter having a pore size of less than 10 microns, and preferably greater than 5 pm, followed by a filtration system having a pore size of less than 2 pm and preferably less than 1 pm.

[0081] According to another particular embodiment, the pretreatment step aO) by filtration comprises at least one filter having a pore size of less than 10 pm, and preferably greater than 5 pm, followed by an electrostatic precipitation system.

[0082] According to another particular embodiment, the pretreatment step aO) by filtration comprises at least one filter with a pore size of less than 10 pm, and preferably greater than 5 pm, followed by a filter system(s) using filtration aids such as sand or diatomaceous earth.

[0083] According to another embodiment, said optional pretreatment step aO) is carried out by centrifugation. According to another embodiment, the pretreatment step aO) comprises centrifugation and filtration.

[0084] According to another embodiment, said optional pretreatment step aO) includes a selective hydrogenation step. This selective hydrogenation step is advantageously implemented in a reaction section fed at least by said feed, optionally pretreated by one or more pretreatments described above, and a gas stream comprising hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature between 100 and 280°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.3 and 10.0 h1, to obtain a hydrogenated effluent.

[0085] This selective hydrogenation step is carried out under hydrogen pressure and temperature conditions that maintain said charge in the liquid phase and with just the amount of soluble hydrogen necessary for selective hydrogenation The selective hydrogenation of diolefins in the pyrolysis oil is advantageously carried out under milder conditions than step a) hydrogenation. Selective hydrogenation of diolefins in the liquid phase thus avoids, or at least limits, the formation of "gums," i.e., the polymerization of diolefins and therefore the formation of oligomers and polymers that can clog the downstream reaction section(s). Styrenic compounds, particularly styrene, which may be present in the feedstock, can also behave like diolefins in terms of gum formation because the double bond of the vinyl group is conjugated with the aromatic ring. This selective hydrogenation step yields a selectively hydrogenated effluent, i.e., an effluent with a reduced olefin content, particularly diolefins and possibly styrenic compounds.

[0086] Said reaction section implements selective hydrogenation, preferably in a fixed bed, in the presence of at least one selective hydrogenation catalyst, advantageously at an average temperature (or WABT as defined below for step a) of hydrogenation) between 100 and 280°C, preferably between 120 and 260°C, preferably between 130 and 250°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs, preferably between 2.0 and 8.0 MPa abs and at a volumetric hourly rate (WH) between 0.3 and 10.0 h1, preferably between 0.5 and 5.0 h1.

[0087] The quantity of the gaseous flow comprising hydrogen (H2), feeding said reaction section of the selective hydrogenation step, is advantageously such that the hydrogen coverage is between 1 and 200 Nm3 of hydrogen per m3 of charge (Nm3 / m3), preferably between 1 and 50 Nm3 of hydrogen per m3 of charge (Nm3 / m3), preferably between 5 and 20 Nm3 of hydrogen per m3 of charge (Nm3 / m3).

[0088] The hourly volumetric velocity (WH) and the hydrogen coverage are such as are defined below for step a) of hydrogenation).

[0089] The selective hydrogenation step is preferably carried out in a fixed bed. It can also be carried out in a bubbling bed or a moving bed.

[0090] Advantageously, the reaction section of said selective hydrogenation step comprises between 1 and 5 reactors. According to a particular embodiment of the invention, the reaction section comprises between 2 and 5 reactors, which operate in a switchable mode, referred to in English as "PRS" for Permutable Reactor System or "lead and lag" as described in hydrogenation step a). According to a particularly preferred variant, the selective hydrogenation reaction section comprises two reactors operating in a switchable mode.

[0091] Said selective hydrogenation catalyst is generally a catalyst as described in hydrogenation step a). It may or may not be identical to the catalyst of hydrogenation step a).

[0092] The impurity content, in particular diolefins, of the hydrogenated effluent obtained at The output of the selective hydrogenation step is reduced compared to that of the same impurities, particularly diolefins, included in the process feed. The selective hydrogenation step generally converts at least 20% and preferably at least 30% of the diolefins contained in the initial feed.

[0093] Advantageously, said optional pretreatment step aO) comprises a filtration step and / or a centrifugation step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step, followed by a selective hydrogenation step.

[0094] Said optional pretreatment step aO) may also optionally be fed with at least a portion of the hydrocarbon effluent from step c) of the process and / or a portion of the first hydrocarbon cut comprising compounds having a boiling point of 175°C or less from step f) and / or a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C from step f), either mixed with or separately from the feed comprising a plastic pyrolysis oil. Recycling at least a portion of the liquid effluent from step c) and / or at least a portion of one or more hydrocarbon effluents from step f) makes it possible, in particular, to increase sedimentation and thus, after possible filtration, to improve the pretreatment of the feed.

[0095] Said optional pretreatment step aO) thus makes it possible to obtain a pretreated feed which then feeds the step b) and / or the hydrogenation step a) when it is present. Step a) Hydrogenation (optional)

[0096] According to the invention, the process optionally includes a step a) of hydrogenation carried out in a hydrogenation reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst, said hydrogenation reaction section being fed at least by said feed, optionally pretreated, and a gas stream comprising hydrogen, said hydrogenation reaction section being carried out at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a hydrogenated effluent.

[0097] Step a) is carried out in particular under hydrogen pressure and temperature conditions enabling the hydrogenation of diolefins, possibly remaining after the optional selective hydrogenation step, and of olefins at the beginning of the hydrogenation reaction section, while also enabling, through a rising temperature profile, the hydrometallation and hydrodechlorination, in particular, to be carried out. End of the hydrogenation reaction section. A sufficient quantity of hydrogen is injected to allow the hydrogenation of at least some of the diolefins and olefins present in the plastic pyrolysis oil, the hydrodemetallation of at least some of the metals, including the retention of silicon, and also the conversion of at least some of the chlorine (to HCl). The hydrogenation of the diolefins and olefins thus prevents, or at least limits, the formation of "gums," i.e., the polymerization of the diolefins and olefins and therefore the formation of oligomers and polymers, which can clog the reaction section of hydrotreating step b). In parallel with hydrogenation, hydrodemetallation, and in particular the retention of silicon during step a), helps to limit the catalytic deactivation of the reaction section of hydrotreating step b).Furthermore, the conditions in step a) allow for the conversion of at least some of the chlorine.

[0098] Temperature control is important in this step and must meet a conflicting constraint. On the one hand, the inlet temperature and the temperature throughout the hydrogenation reaction section must be sufficiently high to allow the hydrogenation of the diolefins and olefins at the beginning of the hydrogenation reaction section. On the other hand, the inlet temperature of the hydrogenation reaction section must be sufficiently low to prevent the catalyst from being deactivated. Since the hydrogenation reactions, particularly of some of the olefins and diolefins, are highly exothermic, a rising temperature profile is observed in the hydrogenation reaction section. This higher temperature at the end of the section allows the hydrometallation and hydrodechlorination reactions to take place.Thus, the temperature at the outlet of the reaction section of step a) is higher than the temperature at the inlet of the reaction section of step a), generally by at least 3°C, preferably by at least 5°C.

[0099] The temperature in step a), whether it be the average temperature (WABT), the temperature at the inlet of the reaction section or the temperature rise in step a) between the inlet and outlet of the reaction section, can in particular be controlled by injecting a diluent into step a), preferably a recycle of part of the liquid effluent from step c) and / or at least part of one or more hydrocarbon effluents from step f), in particular by the recycle rate and / or by the temperature of the recycled effluent.

[0100] The temperature difference between the inlet and outlet of the reaction section of step a) is understood to include the injection of a gaseous (hydrogen) or liquid cooling stream, in particular a portion of the hydrocarbon liquid effluent from step c).

[0101] The temperature difference between the inlet and outlet of the reaction section in step a) is exclusively due to the exothermicity of the chemical reactions carried out in the reaction section and therefore does not involve the use of a heating method (oven, heat exchanger, etc.).

[0102] The inlet temperature of the reaction section of step a) is between 135 and 397°C, preferably between 240 and 347°C.

[0103] The temperature at the outlet of the reaction section of step a) is between 138 and 400°C, preferably between 243 and 350°C.

[0104] According to the invention, it is advantageous to carry out the hydrogenation of the diolefins and part of the hydrometallation reactions in the same step and at a temperature sufficient to limit the deactivation of the catalyst in step a), which manifests itself as a decrease in the conversion of the diolefins. This same step also makes it possible to take advantage of the heats of the hydrogenation reactions, particularly of some of the olefins and diolefins, so as to have a rising temperature profile in this step and thus eliminate the need for a heating device between the catalytic hydrogenation section and the catalytic hydrotreating section.

[0105] Said reaction section implements hydrogenation in the presence of at least one hydrogenation catalyst, advantageously at an average temperature (or WABT as defined below) between 140 and 400°C, preferably between 240 and 350°C, and particularly preferably between 260 and 330°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs, preferably between 1.5 and 8.0 MPa abs. and at a volumetric hourly rate (WH) between 0.1 and 10.0 h1, preferably between 0.2 and 5.0 h1, and most preferably between 0.3 and 3.0 h1.

[0106] According to the invention, the "average temperature" of a reaction section corresponds to the Weight Average Bed Temperature (WABT), a term well known to those skilled in the art. The average temperature is advantageously determined based on the catalytic systems, equipment, and their configuration used. The average temperature (or WABT) is calculated as follows:

[0107] [Math.l] WABT =

[0108] with Tinlet: the temperature of the effluent at the inlet of the reaction section and Toutlet: the temperature of the effluent at the outlet of the reaction section. Unless otherwise specified, the "average temperature" of a reaction section is given at the start of the cycle.

[0109] The hourly volumetric velocity (WH) is defined here as the ratio between the hourly volumetric flow rate of the feed comprising the plastics pyrolysis oil, possibly pre-treated, by the volume of catalyst(s).

[0110] Hydrogen coverage is defined as the ratio of the volumetric flow rate of hydrogen taken under normal temperature and pressure conditions with respect to the volumetric flow rate of "fresh" feed, i.e. the feed to be treated, possibly pre-treated, without taking into account a recycled fraction, and in particular without taking into account the liquid effluent from step c) recycled and / or step f), at 15°C (in normal m3, noted Nm3, of H2 per m3 of feed).

[0111] The quantity of the gaseous flow comprising hydrogen (H2), feeding said reaction section of step a), is advantageously such that the hydrogen coverage is between 100 and 1500 Nm3 of hydrogen per m3 of charge (Nm3 / m3), preferably between 200 and 1000 Nm3 of hydrogen per m3 of charge (Nm3 / m3), preferably between 250 and 800 Nm3 of hydrogen per m3 of charge (Nm3 / m3).

[0112] Hydrogen can be obtained from a fossil source or from a renewable source, for example from the gasification of plastic waste or produced by electrolysis.

[0113] Advantageously, the reaction section of said step a) comprises between 1 and 5 reactors, preferably between 2 and 5 reactors, and particularly preferably comprises two reactors. The advantage of a hydrogenation reaction section comprising several reactors lies in optimized feedstock processing, while reducing the risk of fouling of the catalytic bed(s) and thus preventing unit shutdown due to fouling.

[0114] According to a preferred embodiment, these reactors operate in a switchable mode, known as a "PRS" (Permutable Reactor System) or "lead and lag." Combining at least two reactors in PRS mode allows one reactor to be isolated, the spent catalyst to be discharged, the reactor to be refilled with fresh catalyst, and the reactor to be restarted without interrupting the process. The PRS technology is described, in particular, in patent FR2681871.

[0115] According to a particularly preferred embodiment, the hydrogenation reaction section of step a) comprises two reactors operating in switchable mode.

[0116] Advantageously, reactor internals, for example of the filter plate type, can be used to prevent clogging of the reactor(s). An example of a filter plate is described in patent FR3051375.

[0117] Advantageously, said hydrogenation catalyst comprises a support, preferably mineral, and a hydro-dehydrogenating function.

[0118] According to one embodiment, the hydro-dehydrogenating function comprises in particular at least one element from Group VIII, preferably selected from nickel and cobalt, and at least one element from Group VIB, preferably selected from molybdenum and tungsten. According to this embodiment, the total content, expressed as oxides of the metallic elements from Groups VIB and VIII, is preferably between 1% and 40% by weight, preferably from 5% to 30% by weight relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0119] The weight ratio expressed in metal oxide between the metal (or metals) of group VIB and the metal (or metals) of group VIII is preferably between 1 and 20, and preferably between 2 and 10.

[0120] According to this variant, the reaction section of said step a) comprises for example a hydrogenation catalyst comprising between 0.5% and 12% by weight of nickel, preferably between 0.9% and 10% by weight of nickel (expressed as nickel oxide NiO relative to the weight of said catalyst), and between 1% and 30% by weight of molybdenum, preferably between 3% and 20% by weight of molybdenum (expressed as molybdenum oxide MoO3 relative to the weight of said catalyst) on a support preferably mineral, preferably on an alumina support.

[0121] According to another embodiment, the hydro-dehydrogenating function comprises, and preferably consists of, at least one element from Group VIII, preferably nickel. According to this embodiment, the nickel oxide content is preferably between 1 and 50% by weight, preferably between 10% and 30% by weight relative to the weight of said catalyst. This type of catalyst is preferably used in its reduced form, on a support, preferably mineral, preferably on an alumina support.

[0122] The support for said hydrogenation catalyst is preferably selected from alumina, silica, silica-aluminas, magnesia, clays, and mixtures thereof. This support may contain dopant compounds, in particular oxides selected from boron oxide, especially boron trioxide, zirconia, cerium, titanium dioxide, phosphoric anhydride, and mixtures thereof. Preferably, said hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and optionally with boron. When phosphoric anhydride (P₂O₅) is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. When boron trioxide B2O3 is present, its concentration is less than 10% by weight relative to the weight of alumina and advantageously at least 0.001% relative to the total weight of alumina.The alumina used can be, for example, a y (gamma) or q (eta) alumina.

[0123] Said hydrogenation catalyst is for example in the form of extrudates.

[0124] Preferably, step a) may implement in addition to the ca(s) hydrogenation catalysts described above, in addition to at least one hydrogenation catalyst used in step a) comprising less than 1% by weight of nickel and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, expressed as nickel oxide NiO relative to the weight of said catalyst, and less than 5% by weight of molybdenum and at least 0.1 wt% molybdenum, preferably 0.5 wt% molybdenum, expressed as molybdenum oxide MoO3 relative to the weight of said catalyst, on an alumina support. This low-metal content catalyst can preferably be placed upstream or downstream of the hydrogenation catalyst(s) described above, preferably upstream.

[0125] Preferably, step a) may implement upstream of the hydrogenation catalyst(s) at least one guard bed containing adsorbents of the type alumina, silica-alumina, zeolite and / or activated carbon possibly containing metals of group VIB and / or VIII. A series of guard beds with particles of different diameters may also be used, in particular a series of guard beds having diameters decreasing in the direction of the flow of the charge (also called "grading" according to Anglo-Saxon terminology).

[0126] Said hydrogenation step a) yields a hydrogenated effluent, that is, an effluent with a reduced content of olefins, particularly diolefins, and metals, particularly silicon. The impurity content, particularly diolefins, of the hydrogenated effluent obtained at the end of step a) is reduced compared to that of the same impurities, particularly diolefins, included in the process feed. Hydrogenation step a) generally converts at least 40%, and preferably at least 60%, of the diolefins and at least 40%, and preferably at least 60%, of the olefins contained in the initial feed. The heat released by the saturation of the double bonds raises the temperature of the reaction medium and initiates the hydrotreating reactions, including the removal, at least in part, of other contaminants, such as silicon and chlorine.Preferably, at least 50%, and more preferably at least 75%, of the chlorine and silicon in the initial feedstock are removed during step a). The hydrogenated effluent obtained at the end of step a) hydrogenation is sent, preferably directly, to step b) hydrotreatment. Step b) of hydrotreatment

[0127] According to the invention, the treatment process comprises a hydrotreating step b) carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst, said hydrotreating reaction section being fed at least by the feed, optionally pretreated in step a0), or said hydrogenated effluent from step a) and a gas stream comprising hydrogen, said hydrotreating reaction section being carried out at an average temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h1, to obtain a hydrotreated effluent.

[0128] Advantageously, step b) implements the hydrotreating reactions well known to those skilled in the art, and more specifically to hydrotreating reactions such as aromatic hydrogenation, hydrodesulfurization, and hydrodeazotation. In addition, the hydrogenation of olefins and remaining halogenated compounds, as well as hydrodemetallation, are carried out.

[0129] Said hydrotreating reaction section is advantageously implemented at a pressure equivalent to that used in the reaction section of step a) of hydrogenation, and generally at a higher average temperature than that of the reaction section of step a) of hydrogenation. Thus, said hydrotreating reaction section is advantageously implemented at an average hydrotreating temperature between 250 and 430°C, preferably between 280 and 380°C, at a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and at a volumetric rate per hour (WH) between 0.1 and 10.0 h1, preferably between 0.1 and 5.0 h1, preferably between 0.2 and 2.0 h1, preferably between 0.2 and 1h'.The hydrogen coverage in step b) is advantageously between 100 and 1500 Nm3 of hydrogen per m3 of fresh feed, and preferably between 200 and 1000 Nm3 of hydrogen per m3 of fresh feed, and more preferably between 250 and 800 Nm3 of hydrogen per m3 of fresh feed. The definitions of mean temperature (WABT), WH, and hydrogen coverage correspond to those described above.

[0130] The hydrotreating step is preferably carried out in a fixed bed. It can also be carried out in a bubbling bed, a driven bed, or a moving bed. When the hydrotreating step is carried out in a bubbling bed, a driven bed, or a moving bed, an additional fixed-bed hydrotreating step can be carried out under the same operating conditions after the bubbling bed, driven bed, or moving bed step, with or without intermediate separation of a gas stream.

[0131] Preferably, the treatment process includes a hydrotreating step b) carried out in a hydrotreating reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreating catalyst.

[0132] Said hydrotreating reaction section is fed at least by the feedstock or hydrogenated effluent from step a) and a gaseous stream including hydrogen, advantageously at the first catalytic bed of the first operating reactor. Injection of at least a portion of the feedstock or hydrogenated effluent from step a) and / or at least a portion of hydrogen between the different catalytic beds is also possible. Optionally, the reaction section of said step b) may also be further fed by at least a portion of the liquid effluent from step c) and / or by at least a portion of one of the effluents from step f).

[0133] Advantageously, said step b) is carried out in a hydrotreating reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrotreating catalysts. When a reactor comprises several catalytic beds, i.e. at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are preferably arranged in series in said reactor.

[0134] When step b) is implemented in a hydrotreating reaction section comprising several, preferably two, reactors, these reactors can operate in series and / or in parallel and / or in switchable (or PRS) mode and / or in swing mode. The various possible operating modes, PRS (or lead and lag) mode and swing mode, are well known to those skilled in the art and are advantageously defined above.

[0135] In another embodiment of the invention, said hydrotreating reaction section comprises a single fixed-bed reactor containing n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five.

[0136] In a particularly preferred mode, the hydrogenation reaction section of step a) comprises two reactors operating in switchable mode followed by the hydrotreating reaction section of step b) which comprises a single fixed-bed reactor.

[0137] Advantageously, said hydrotreating catalyst used in said step b) can be selected from known hydrodemetallation, hydrotreating, silicon capture catalysts, used in particular for the treatment of petroleum cuts, and their combinations. Examples of known hydrometallation catalysts are those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616, and US 5089463. Examples of known hydrotreating catalysts are those described in patents EP 0113297, EP 0113284, US 6589908, US 4818743, and US 6332976. Examples of known silicon capture catalysts are those described in patent applications CN 102051202 and US 2007 / 080099.

[0138] In particular, said hydrotreating catalyst comprises a support, preferably mineral, and at least one metallic element having a hydro-dehydrogenating function. Said metallic element having a hydro-dehydrogenating function advantageously comprises at least one element of Group VIII, preferably selected from the group consisting of nickel and cobalt, and / or at least one element of Group VIB, of The metal is preferably chosen from the group consisting of molybdenum and tungsten. The total content, expressed as oxides of the metallic elements of groups VIB and VIII, is preferably between 0.1% and 40% by weight, and more preferably between 5% and 35% by weight, relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO, respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3, respectively. The weight ratio, expressed as metal oxide, of the metal(s) of group VIB to the metal(s) of group VIII is preferably between 1.0 and 20, and more preferably between 2.0 and 10.For example, the hydrotreating reaction section of step b) of the process comprises a hydrotreating catalyst comprising between 0.5% and 10% by weight of nickel, preferably between 1% and 8% by weight of nickel, expressed as nickel oxide NiO relative to the total weight of the hydrotreating catalyst, and between 1.0% and 30% by weight of molybdenum, preferably between 3.0% and 29% by weight of molybdenum, expressed as molybdenum oxide MoO3 relative to the total weight of the hydrotreating catalyst, on a mineral support, preferably on an alumina support.

[0139] The support for said hydrotreating catalyst is advantageously selected from alumina, silica, silica-aluminas, magnesia, clays, and mixtures thereof. This support may further contain doping compounds, in particular oxides selected from boron oxide, especially boron trioxide, zirconia, cerium, titanium dioxide, phosphoric anhydride, and mixtures thereof. Preferably, said hydrotreating catalyst comprises an alumina support, more preferably an alumina support doped with phosphorus and optionally boron. When phosphoric anhydride (P₂O₅) is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina.When boron trioxide B2O3 is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may be, for example, a γ (gamma) or θ (eta) alumina.

[0140] Said hydrotreating catalyst is for example in the form of extrudates.

[0141] Advantageously, said hydrotreating catalyst used in step b) of the process has a specific surface area greater than or equal to 250 m² / g, preferably greater than or equal to 300 m² / g. The specific surface area of ​​said hydrotreating catalyst is advantageously less than or equal to 800 m² / g, preferably less than or equal to 600 m² / g, in particular less than or equal to 400 m² / g. The specific surface area of ​​the hydrotreating catalyst is measured by the BET method, i.e., the specific surface area determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method described in the periodical 'The Journal of the American Chemical Society', 6Q, 309 (1938). Such a specific surface area further improves the removal of contaminants, particularly metals such as silicon.

[0142] According to another aspect of the invention, the hydrotreating catalyst as described above further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such a catalyst is often referred to as an "additized catalyst." Generally, the organic compound is chosen from a compound having one or more chemical functions selected from among a carboxyl group, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide, or compounds including a furan ring, or sugars.

[0143] Preferably, step b) may implement upstream of the hydrogenation catalyst(s) at least one guard bed or a series of guard beds of the "grading" type as described above for step a).

[0144] Advantageously, hydrotreating step b) enables the hydrogenation of at least 80%, and preferably all, of the olefins remaining after hydrogenation step a), but also the conversion, at least in part, of other impurities present in the feedstock, such as aromatic compounds, metallic compounds, sulfur compounds, nitrogen compounds, halogenated compounds (in particular chlorinated compounds), and oxygenated compounds. Preferably, the nitrogen content at the outlet of step b) is less than 100 ppm by weight. Preferably, the sulfur content at the outlet of step b) is less than 100 ppm by weight. Step b) can also further reduce the contaminant content, such as that of metals, in particular silicon. Preferably, the metal content at the output of step b) is less than 10 ppm by weight, and preferably less than 2 ppm by weight, and the silicon content is less than 5 ppm by weight.

[0145] Depending on the content of sulfur compounds in the initial feed to be treated, a stream containing a sulfurizing agent can be injected upstream of the optional pretreatment step aO), of the optional hydrogenation step a) and / or the hydrotreating step b) and / or upstream of one of the optional hydrocracking steps g) when present, preferably upstream of the hydrogenation step a) and / or the hydrotreating step b) in order to ensure a sufficient quantity of sulfur to form the active species of the catalyst (in sulfide form).

[0146] This activation or sulfidation step is carried out by methods well known to those skilled in the art, and advantageously under a sulfur-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. The sulfidating agents are preferably H2S gas, elemental sulfur, CS2, mercaptans, sulfides and / or Polysulfides, hydrocarbon fractions with a boiling point below 400°C containing sulfur compounds, or any other sulfur-containing compound used for activating hydrocarbon feedstocks to sulfide the catalyst. These sulfur-containing compounds are advantageously selected from alkyl disulfides, such as dimethyl disulfide (DMDS), alkyl sulfides, such as dimethyl sulfide, thiols, such as n-butyl mercaptan (or 1-butanethiol), and tertiononyl polysulfide-type polysulfide compounds. The catalyst can also be sulfided with sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfided in situ in the presence of a sulfurizing agent and a hydrocarbon feedstock. Most preferably, the catalyst is sulfided in situ in the presence of the feedstock supplemented with dimethyl disulfide.

[0147] The injection of a sulfurizing agent is particularly necessary at the beginning of the catalytic cycle, while the H2S is being formed to be separated in step d) and recycled upstream of step a) and / or step b) and / or step g), or / upstream of the selective hydrogenation step of the pretreatment aO). Additional injections throughout the catalytic cycle may be necessary to compensate for natural loss. However, the ability to recycle a gaseous phase containing H2S without NH3 by the present invention makes it possible to considerably reduce the consumption of the sulfurizing agent. Step c) of separation

[0148] According to the invention, the treatment process comprises a separation step c), advantageously implemented in at least one washing / separation section, fed at least by the hydrotreated effluent from step b), and optionally by the hydrocracked effluent from the optional steps g) and g'), and an aqueous solution, to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent.

[0149] The gaseous effluent obtained at the end of step c) advantageously comprises hydrogen, preferably comprising at least 80% by volume, preferably at least 85% by volume, of hydrogen. Advantageously, said gaseous effluent can be at least partially recycled to the steps a) hydrogenation and / or b) hydrotreating and / or g) hydrocracking, the recycling system being able to include a purification section.

[0150] The gaseous effluent can also be subjected to further separation(s) in order to recover at least one hydrogen-rich gas and / or light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent separately or in mixture to one or more furnaces of step h) of steam cracking so as to increase the overall olefin yield.

[0151] The hydrocarbon effluent from separation step c) is sent, in part or in the entirety, either directly into a steam cracking unit, or to an optional fractionation step f). Preferably, the hydrocarbon liquid effluent is sent, in part or in whole, to a fractionation step f).

[0152] The first aqueous effluent obtained at the end of step c) advantageously comprises ammonium salts and / or hydrochloric acid as well as dissolved H2S and NH3.

[0153] This separation step c) makes it possible, in particular, to remove ammonium chloride salts, which are formed by the reaction between chloride ions, released by the hydrogenation of chlorinated compounds in the form of HCl, notably during steps a) and b) followed by dissolution in water, and ammonium ions, generated by the hydrogenation of nitrogen compounds in the form of NH3, notably during step b) and / or supplied by the injection of an amine followed by dissolution in water, and thus to limit the risk of blockage, particularly in the transfer lines and / or in the sections of the process of the invention and / or the transfer lines to the steam cracker, due to the precipitation of ammonium chloride salts. It also makes it possible to remove the hydrochloric acid formed by the reaction of hydrogen ions and chloride ions.This step c) also allows the elimination of ammonium sulfide salts ((NH4)2S) which are formed by reaction between H2S from the hydrodesulfurization of sulfide compounds and NH3.

[0154] Depending on the content of chlorinated compounds in the initial feed to be treated, a stream containing a nitrogenous compound such as an amine, for example monoethanolamine, diethanolamine and / or monodiethanolamine can be injected upstream of the selective hydrogenation step of the pretreatment aO) and / or upstream of the hydrogenation step a) and / or between the hydrogenation step a) and the hydrotreating step b) and / or between the hydrocracking step g) and the separation step c), preferably upstream of the hydrogenation step a) in order to ensure a sufficient quantity of ammonium ions to combine the chloride ions formed during the hydrotreating step, thus limiting the formation of hydrochloric acid and thus limiting corrosion downstream of the separation section.

[0155] According to one variant, said gaseous phase containing NH3 from step e) can also be used as a nitrogen compound.

[0156] Advantageously, the separation step c) includes an injection of an aqueous solution, preferably an injection of water, into the hydrotreated effluent from step b), or the hydrocracked effluent from the optional step g), upstream of the washing / separation section, so as to dissolve at least some of the ammonium chloride salts and / or hydrochloric acid and thus improve the removal of chlorinated impurities and reduce the risks of blockages due to an accumulation of ammonium chloride salts.

[0157] Step c) of separation is advantageously carried out at a temperature between 20 and 450°C, preferably between 100 and 440°C, preferably between 200 and 420°C. It is important to operate within this temperature range (and therefore not to overcool the treated effluent) to avoid the risk of blockages in the lines due to the precipitation of ammonium chloride salts. Advantageously, separation step c) is carried out at a pressure close to that used in steps a) and / or b), preferably between 1.0 and 10.0 MPa, in order to facilitate hydrogen recycling.

[0158] The separation step can advantageously be carried out by any method known to those skilled in the art, such as, for example, the combination of one or more separator(s) (balloon(s)) and / or one or more stripping column(s), this separator(s) (balloon(s)) and / or column(s) optionally being supplied with a stripping gas, for example, a hydrogen-rich gas stream. The washing / separation section of step c) can be at least partially carried out in common or separate washing and separation equipment.

[0159] In a possible embodiment of the invention, step c) of separation comprises the injection of an aqueous solution into the hydrotreated effluent from step b), followed by the washing / separation section advantageously comprising a separation phase enabling the production of at least a first aqueous effluent containing ammonium salts, a washed liquid hydrocarbon effluent, and a partially washed gaseous effluent. Said first aqueous effluent containing ammonium salts and the washed liquid hydrocarbon effluent can then be separated in a settling tank to obtain said hydrocarbon effluent and said first aqueous effluent.The partially washed gaseous effluent can simultaneously be introduced into a scrubbing column where it flows counter-currently to an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrotreated effluent. This allows for the removal, at least in part, and preferably in full, of the hydrochloric acid contained in the partially washed gaseous effluent, thus obtaining the gaseous effluent, preferably consisting essentially of hydrogen, and an acidic aqueous stream. The first aqueous effluent from the settling tank can optionally be mixed with the acidic aqueous stream and used, possibly mixed with the acidic aqueous stream, in a water recycling circuit to supply step c) of the separation of the aqueous solution upstream of the scrubbing / separation section and / or the aqueous stream in the scrubbing column.The said water recycling circuit may include a water top-up and / or a basic solution and / or a purge to remove dissolved salts.

[0160] In another possible embodiment of the invention, the separation step c) may advantageously include a "high-pressure" washing / separation section that operates at a pressure close to the pressure of the hydrogenation step a) and / or the hydrotreating step b) and / or the optional hydrocracking step g), preferably between 1.0 and 10.0 MPa, to facilitate hydrogen recycling. This optional "high-pressure" section of step c) can be supplemented by a "low-pressure" section to obtain a hydrocarbon effluent free of some of the high-pressure dissolved gases, intended for direct treatment in a steam cracking process or, optionally, for use in step f) of fractionation. Variant step c) of two-stage separation

[0161] In a possible embodiment of the invention, step c) of separation comprises the following steps:

[0162] c1) a separation step, fed by the hydrotreated effluent from step b), said step being operated at a temperature between 200 and 450°C and at a pressure substantially the same as the pressure of step b) to obtain at least one gaseous effluent and one liquid effluent, part of which can be recycled upstream of step a) and / or step b), c2) a separation step, fed by the gaseous effluent from step c1) and another part of the liquid effluent from step c1) and an aqueous solution, said step being operated at a temperature between 20 and below 200°C, and at a pressure substantially the same as or below the pressure of step b), to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent. Step c1)

[0163] According to the invention, the treatment process may include a separation step cl), fed by the hydrotreated effluent from step b), said step being carried out at a temperature between 200 and 450°C and at a pressure substantially identical to the pressure of step b) to obtain at least one gaseous effluent and one liquid effluent, part of which can be recycled upstream of step a) and / or step b).

[0164] The separation step cl) is a so-called high-pressure or medium-pressure, high-temperature separation step, also known to those skilled in the art as HHPS (for "Hot High Pressure Separator" in Anglo-Saxon terminology). Thus, this step cl) preferably uses a so-called "hot high-pressure separator," the pressure being substantially equal to the operating pressure of step b). "Pressure substantially equal to the pressure of step b)" means the pressure of step b) with a pressure difference of between 0 and 1 MPa, preferably between 0.005 and 0.3 MPa, and particularly preferably between 0.01 and 0.2 MPa, relative to the pressure of step b). Preferably, the pressure of step cl) is the pressure of step b) less the pressure losses.

[0165] The temperature at which the separation is carried out is between 200 and 450°C, preferably between 220 and 330°C, and particularly preferably between 240 and 300°C. According to a preferred variant, and in order to recover the most calories, the separation is carried out at the highest possible temperature but less than or equal to the outlet temperature of step b), which avoids or limits the reheating (and therefore the need for calories) of the effluent from step b). According to another variant, the effluent from step b) can be heated or cooled before separation.

[0166] This separation step (c) can advantageously be carried out by any method known to those skilled in the art, such as, for example, the combination of one or more separators (balloons) and / or one or more stripping columns, these separators (balloons) and / or columns optionally being supplied with a stripping gas, for example, a hydrogen-rich gas stream. Preferably, step (c) is carried out with a single separator (balloon).

[0167] Part of the liquid effluent can be recycled upstream of step a) and / or step b) and / or upstream of the selective hydrogenation step of the pretreatment aO). Recycling part of the product obtained to or upstream of at least one of the reaction steps advantageously allows, on the one hand, the dilution of impurities and, on the other hand, the control of the temperature in the reaction step(s), in which reactions involved may be strongly exothermic. Advantageously, the quantity of liquid effluent from step c) recycled, i.e. the recycled fraction of product obtained, is adjusted so that the weight ratio between the recycled stream from step c) and the feed comprising a plastics pyrolysis oil, i.e. the feed to be treated feeding the overall process, is less than or equal to 10, preferably less than or equal to 7, and preferably greater than or equal to 0.001, preferably greater than or equal to 0.01, and preferably greater than or equal to 0.1. Preferably, the quantity of liquid effluent from step c) recycled is adjusted so that the weight ratio between the recycle stream and the feed including plastic pyrolysis oil is between 0.01 and 10, preferably between 0.1 and 7, and particularly preferably between 0.2 and 5. This recycle rate makes it possible in particular to control the temperature rise in step a).Indeed, when the recycle rate is high, the feed dilution rate is high, and the temperature rise at the beginning of the reaction section of step a), notably due to the hydrogenation reactions of diolefins, is thus controllable by the dilution effect.

[0168] High-pressure, high-temperature separation makes it possible, on the one hand, to maximize energy recovery by hot recycling a portion of the liquid effluent. Indeed, the energy required to reach the inlet temperature in step a) and / or step b) can be at least partially supplied by the heat from a portion of the liquid effluent from step c), and also makes it possible to reduce or even eliminate any potential Preheating by directly heating the charge above a temperature exceeding 200°C prevents gum formation. Furthermore, recycling at least some of the high-pressure liquid effluent saves energy for its pressurization in step a) and / or step b).

[0169] High-pressure, high-temperature separation also minimizes the amount of light fraction (hydrocarbon fraction comprising compounds with a boiling point of 175°C or lower, or naphtha) contained in the liquid effluent recycled in step a) and / or step b). At this temperature, almost all of the light fraction of the effluent (naphtha) is released as a gaseous effluent to the separation / washing step c2), while the liquid phase consists mainly of the heavy fraction of the feedstock (hydrocarbon fraction comprising compounds with a boiling point above 175°C, or middle distillates). In this way, the ppH2 is increased in step a) and / or step b) because the light fraction (naphtha) could partially vaporize and lower the ppH2 if it were not at least partially removed during the high-pressure, high-temperature separation.The removal of the light fraction containing naphtha can optionally be increased by a slight expansion upstream of at least one separator implemented in step cl), although this implementation is not preferred due to the energy loss associated with the expansion. Another option for increasing the removal of the light fraction containing naphtha could be to perform stripping, for example by injecting a hydrogen-rich gas in step cl).

[0170] According to a preferred embodiment, at least a portion of the hydrotreated liquid effluent from step c) may advantageously be either cooled, or preheated, if necessary, or kept at the same temperature as at the outlet of separation step c), before being advantageously recycled upstream of hydrogenation step a) and / or hydrotreating step b), depending on the temperature and flow rate of feed and hydrogen, so that the temperature of the incoming stream, comprising said feed mixed with at least a portion of said liquid effluent from step c) and a hydrogen-rich gas, is between 140 and 430°C, preferably between 220 and 350°C, and particularly preferably between 260 and 330°C.

[0171] In the case where at least part of the liquid effluent from separation step c) is pre-heated before being recycled upstream of step a) and / or step b), said effluent may pass through at least one exchanger and / or at least one furnace before being recycled upstream of step a) and / or step b), so as to adjust the temperature of said recycled liquid effluent.

[0172] In the case where at least part of the liquid effluent from separation step c) is cooled before being recycled upstream of step a) and / or step b), said effluent may pass through at least one heat exchanger and / or at least one aerator refrigerant before being recycled upstream of step a) and / or step b), so as to adjust the temperature of said recycled liquid effluent.

[0173] Implementing the recycle upstream of step a) of hydrogenation and / or upstream of step b) of hydrotreatment, of at least a part of the liquid effluent from step c) which can be either cooled or preheated, if necessary, or kept at the same temperature as at the outlet of step c) of separation, therefore makes it possible to adjust the temperature of the incoming flow at step a) and / or at step b), as required.

[0174] According to one embodiment, the feed, before being mixed with at least a portion of the effluent from step c), can be preheated by direct heating to a temperature of up to 200°C, preferably up to 180°C, and particularly preferably up to 150°C. Above this temperature, contact with a wall during direct heating can induce the formation of gums and / or coke, which can cause fouling and an increase in the pressure drop of the feed heating system as well as of the catalyst bed(s). Heating the feed to a temperature above 150°C, preferably above 180°C, and particularly preferably above 200°C, is preferably carried out by indirect heating with at least a portion of the effluent from step c).Thus, the temperature rise above 150°C, preferably above 180°C, and particularly preferably above 200°C, of ​​the load is caused by mixing with a hotter liquid, and not by contact with a heated wall. According to another variant, the heating of the load to a temperature above 150°C, preferably above 180°C, and particularly preferably above 200°C, is carried out by furnaces or heat exchangers sized to have a very low wall temperature compared to the temperature of the load, for example, an electric furnace.

[0175] According to another embodiment, the feed is entirely heated by indirect heating from at least a portion of the effluent from step c). In this case, the feed is not preheated before being mixed with at least a portion of the effluent from step c).

[0176] According to another variant, the feed is not heated by indirect heating by at least part of the effluent from step c). In this case, the feed and the part of the effluent from step c) recycled are mixed, the part of the effluent from step c) recycled having substantially the same temperature or a lower temperature than the feed.

[0177] Another heating stream advantageously consists of a hydrogen-rich gaseous effluent from the hydrogen make-up and / or the gaseous effluent from separation step c). At least a portion of this hydrogen-rich gaseous effluent from the hydrogen make-up and / or the gaseous effluent from separation step c- The preparation is advantageously injected in mixture with at least part of the liquid effluent from step c) or separately, upstream of step a) and / or step b). The hydrogen-rich gas stream can therefore advantageously be either pre-heated in mixture with at least part of the liquid effluent or pre-heated separately before mixing, preferably by passing through at least one exchanger and / or at least one furnace or any other means of heating known to those skilled in the art. Step c2)

[0178] According to the invention, the treatment process comprises a separation step c2), advantageously implemented in at least one washing / separation section, fed by the first gaseous effluent and another part of the liquid effluent from step c1) and an aqueous solution, said step being carried out at a temperature between 20 and below 200°C, and at a pressure substantially the same as or below the pressure of step b), to obtain at least one gaseous effluent, one first aqueous effluent and one hydrocarbon effluent.

[0179] The separation step c2) is carried out in at least one so-called high-pressure or medium-pressure, low-temperature separator vessel, also known to those skilled in the art as CHPS (for "Cold High Pressure Separator" in Anglo-Saxon terminology). Thus, this step c2) preferably uses a so-called "cold high-pressure separator," the pressure being substantially equal to the operating pressure of step b). "Pressure substantially equal to the pressure of step b)" means the pressure of step b) with a pressure difference of between 0 and 1 MPa, preferably between 0.005 and 0.3 MPa, and particularly preferably between 0.01 and 0.2 MPa, relative to the pressure of step b). Preferably, the pressure of step c2) is the pressure of step b) less the pressure losses.Furthermore, carrying out at least part of the separation step c2) at a pressure substantially identical to the operating pressure of step b) facilitates hydrogen recycling.

[0180] The separation step c2) can also be carried out at a pressure lower than the pressure of step b).

[0181] The separation step c2) may also include a (first) separation step at a pressure substantially equal to the operating pressure of step b), followed by at least one other separation step carried out at the same or lower temperature and pressure as each separation step of the preceding step c2).

[0182] The temperature at which the separation of step c2) is carried out is between 20 and less than 200°C, preferably between 25 and 120°C, and particularly preferably between 30 and 70°C.

[0183] It is important to operate within this temperature range (and therefore not to overcool the hydrotreated effluent) to avoid the risk of blockage in the lines due to the precision pittion of ammonium chloride salts.

[0184] The washing / separation section of step c2) can be at least partly carried out in common or separate washing and separation equipment, such equipment being well known (separating vessels capable of operating at different pressures and temperatures, pumps, heat exchangers, washing columns, etc.). In particular, the separation step c2) can be carried out as described in step c) above.

[0185] When one (or two) hydrocracking steps are present (described below), this step c2) can in addition be fed by at least part of the hydrocracking effluent from an optional hydrocracking step g).

[0186] At least a portion of the hydrocarbon effluent from step c2) can be recycled as a quench upstream of step a and / or step b) and / or step g). The injection of the hydrocarbon effluent from step c2) can be carried out at the first catalytic bed of the reaction section of step a) and / or step b) and / or step g) or between the different catalytic beds of each section. When the hydrogenation reaction section of step a) comprises two reactors operating in switchable mode, at least a portion of the hydrocarbon effluent from step c2) can be recycled between the two reactors.

[0187] Step d) of separating the H2S contained in the first aqueous effluent

[0188] According to the invention, the treatment process comprises a step d) of separating the H2S contained in the first aqueous effluent to obtain a gaseous phase containing the H2S and a second aqueous effluent, said gaseous phase containing the H2S is preferably at least partly recycled upstream of step a) and / or step b) and / or step g).

[0189] Step d) of separating the H2S contained in the first aqueous effluent is advantageously carried out by stripping with a gas stream, preferably inert, in a stripping column. A stripping column is a distillation column into which a gas stream, preferably inert, is injected at the bottom of the column. The gas phase containing the H2S is recovered at the top of the column and a second aqueous effluent is recovered at the bottom of the column. The inert gas stream can be hydrogen, nitrogen, or steam. Preferably, step d) is carried out by steam stripping.

[0190] Stripping using a gaseous flow, preferably inert, makes it possible to obtain a very low content of dissolved H2S in the second aqueous effluent at the bottom of the stripping column.

[0191] Step d) of H2S separation is generally carried out at a pressure between 0.5 and 1.5 MPa, preferably between 0.5 and 1 MPa, and in a particular manner- preferred range between 0.6 and 0.9 MPa.

[0192] Stripping is generally carried out at a temperature between 80 and 150°C, preferably between 120 and 145°C (at the top and bottom of the column respectively).

[0193] The inert gas flow rate is generally such that the ratio between the inert gas flow rate expressed in normal m3 per hour (Nm3 / h) and the flow rate of the first aqueous effluent to be treated expressed in m3 per hour under standard conditions (15°C, 0.1 MPa) is between 50 and 600 Nm3 / m3, preferably between 200 and 400 Nm3 / m3. Normal m3 refers to the quantity of gas in a volume of 1 m3 at 0°C and 0.1 MPa.

[0194] Stripping carried out under these operating conditions makes it possible in particular to separate H2 S from said first aqueous effluent without carrying away the NH3 (which remains predominantly in the aqueous phase).

[0195] According to one embodiment, in step d) a portion of the gaseous phase at the top of the stripping column, comprising H2S and the inert gas stream (vapor), is condensed and is preferably reinjected, at least in part, as liquid reflux into the upper part of the stripping column. The condensation is generally carried out by cooling to a temperature between 30 and 65°C, for example with cold water.

[0196] Liquid reflux allows control / reduction of the temperature at the top of the stripping column.

[0197] The gaseous phase containing the H2S withdrawn from the top of the stripping column is at least partially recycled upstream of step a) and / or step b) and / or upstream of step g) of hydrocracking and / or upstream of the selective hydrogenation step of the pretreatment aO) when present, in order to act as a sulfurizing agent for the catalyst(s). Before its recycling, it may undergo at least one additional purification step, for example, contact with liquid or amine washing.

[0198] According to another variant, step d) of separating the H2S contained in the first aqueous effluent can also be carried out by liquid / liquid extraction in which an inert or reactive solvent is brought into contact with the aqueous effluent.

[0199] Step e) of separation of the NH3 contained in the second aqueous effluent

[0200] According to the invention, the treatment process comprises a step e) of separating the NH3 contained in the second aqueous effluent from step d) to obtain a gaseous phase containing NH3 and a third aqueous effluent, said gaseous phase containing NH3 is preferably at least partly recycled upstream of step a) and / or step b) and / or step g).

[0201] Step e) of separating the NH3 contained in the second aqueous effluent is advantageously carried out by stripping using an inert gas stream in a stripping column. The gaseous phase containing NH3 is recovered at the top of the column and a The third aqueous effluent is collected at the bottom of the column. The inert gas stream can be hydrogen, nitrogen, or steam. Preferably, step e) is carried out by steam stripping.

[0202] Stripping using an inert gas flow makes it possible to obtain a very low content of dissolved NH3 at the bottom of the stripping column allowing the recovery of a third aqueous effluent which can be introduced into a conventional wastewater treatment.

[0203] The NH3 separation step e) is generally carried out at a pressure between 0.1 and less than 0.5 MPa, preferably between 0.05 and 0.2 MPa.

[0204] Stripping is generally carried out at a temperature between 80 and 150°C, preferably between 120 and 145°C (at the top and bottom of the column respectively).

[0205] The flow rate of the inert gas stream is generally such that the ratio between the flow rate of the inert gas stream expressed in normal m3 per hour (Nm3 / h) and the flow rate of the feed to be treated expressed in m3 per hour under standard conditions (15°C, 0.1 MPa) is between 50 and 600 Nm3 / m3, preferably between 200 and 400 Nm3 / m3. Normal m3 refers to the quantity of gas in a volume of 1 m3 at 0°C and 0.1 MPa.

[0206] According to one embodiment, in step e) a portion of the gaseous phase at the top of the stripping column, comprising NH3 and the inert gas stream (vapor), is condensed and is preferably reinjected, at least in part, as liquid reflux into the upper part of the stripping column. The condensation is generally carried out by cooling to a temperature between 30 and 65°C, for example with cold water.

[0207] Liquid reflux allows control / reduction of the temperature at the top of the stripping column.

[0208] According to one variant, said gaseous phase containing NH3 can be at least partly recycled upstream of step a) and / or step b) and / or step g), and / or upstream of the selective hydrogenation step aO), advantageously in stoichiometric quantities adapted to the formation of salts during the separation / washing step c). Step f) (optional) of splitting

[0209] The process according to the invention may include a step of fractionating all or part, preferably all, of the hydrocarbon effluent from step c), to obtain at least one gaseous stream and at least two liquid hydrocarbon streams, said two liquid hydrocarbon streams being at least a first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C (naphtha cut), in particular between 80 and 175°C, and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C (middle distillates cut).

[0210] Step f) makes it possible in particular to eliminate the gases dissolved in the liquid effluent hy drocarbon, such as ammonia, hydrogen sulfide and light hydrocarbons having 1 to 4 carbon atoms.

[0211] The optional fractionation step f) is advantageously carried out at a pressure less than or equal to 3.0 MPa abs., preferably between 0.5 and 2.5 MPa abs.

[0212] According to one embodiment, step f) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit including a reflux flask. Said stripping column is fed by the hydrocarbon liquid effluent from step c) and by a stream of steam. The hydrocarbon liquid effluent from step c) may optionally be heated before entering the stripping column. Thus, the lighter compounds are carried to the top of the column and into the reflux circuit including a reflux flask in which a gas / liquid separation takes place. The gaseous phase, which includes the light hydrocarbons, is withdrawn from the reflux flask as a gas stream. The hydrocarbon fraction, comprising compounds having a boiling point less than or equal to 175°C, is advantageously withdrawn from the reflux flask.The hydrocarbon fraction comprising compounds having a boiling point above 175°C is advantageously drawn off from the bottom of the stripping column.

[0213] According to other embodiments, the fractionation step f) can employ a stripping column followed by a distillation column or only a distillation column.

[0214] Depending on the destination or use of the fractions from step f) of fractionation, a person skilled in the art will adjust the cut points in the stripping and / or distillation operations. For example, it may be necessary to adjust the endpoint of the naphtha cut to 150, 175 or 200°C.

[0215] The first hydrocarbon fraction comprising compounds having a boiling point of 175°C or lower and the second hydrocarbon fraction comprising compounds having a boiling point above 175°C, possibly mixed, may be sent, in whole or in part, to a steam cracking unit, at the end of which olefins may be (re)formed to participate in polymer formation. Preferably, only a portion of said fractions is sent to a steam cracking unit; at least a fraction of the remaining portion is optionally recycled in at least one of the process steps and / or sent to a fuel storage unit, for example, a naphtha storage unit, a diesel storage unit, or a kerosene storage unit, derived from conventional petroleum feedstocks.

[0216] According to a preferred method, the first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C, in whole or in part, is sent to a steam cracking unit, while the second hydrocarbon cut comprising compounds having a boiling point above 175°C is sent to a hydrocracking step g) and / or sent to a fuel storage unit.

[0217] In a particular embodiment, the optional fractionation step f) can provide, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point less than or equal to 175°C, preferably between 80 and 175°C, and a middle distillates cut comprising compounds having a boiling point greater than 175°C and less than 385°C, and a hydrocarbon cut comprising compounds having a boiling point greater than or equal to 385°C, referred to as a heavy hydrocarbon cut.The naphtha cut can be sent, in whole or in part, to a steam cracking unit and / or to the naphtha storage unit from conventional petroleum feedstocks, or it can also be recycled; the middle distillate cut can also be sent, in whole or in part, either to a steam cracking unit, or to a diesel storage unit from conventional petroleum feedstocks, or it can also be recycled; the heavy cut can, for its part, be sent, at least in part, to a steam cracking unit, or be sent to the hydrocracking step (g) when present.

[0218] In another particular embodiment, the optional fractionation step f) can provide, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point less than or equal to 175°C, preferably between 80 and 175°C, and a kerosene cut comprising compounds having a boiling point greater than 175°C and less than or equal to 280°C, a diesel cut comprising compounds having a boiling point greater than 280°C and less than 385°C and a hydrocarbon cut comprising compounds having a boiling point greater than or equal to 385°C, referred to as a heavy hydrocarbon cut. The naphtha cut, the kerosene cut and / or the diesel cut can be, in whole or in part, either sent to a steam cracking unit, or respectively to a naphtha, kerosene or diesel pool from conventional petroleum feedstocks, or recycled.The heavy cut can, at least in part, be sent to a steam cracking unit, or be sent to the hydrocracking step (g) when present.

[0219] In another particular embodiment, the naphtha cut comprising compounds having a boiling point of 175°C or less from step f) is fractionated into a heavy naphtha cut comprising compounds having a boiling point between 80 and 175°C and a light naphtha cut comprising compounds having a boiling point below 80°C, at least a portion of said heavy naphtha cut being sent to an aromatic complex comprising at least one naphtha reforming step for the production of aromatic compounds. According to this embodiment, at least a portion of the light naphtha cut is sent into step h) of steam cracking described below.

[0220] The gaseous effluent(s) from step f) of fractionation may be subjected to further purification and separation in order to recover at least light hydrocarbons, in particular ethane, propane and butane, which may advantageously be sent separately or mixed to one or more furnaces of step h) of steam cracking so as to increase the overall olefin yield. (Optional) step g) of hydrocracking

[0221] According to one variant, the process of the invention may include a step g) of hydrocracking carried out after step c) of separation with at least a part of said hydrocarbon effluent from step c) or carried out after step f) of fractionation with at least a part of the second hydrocarbon cut comprising compounds having a boiling point above 175°C.

[0222] Advantageously, step g) implements hydrocracking reactions well known to those skilled in the art, and more specifically allows the conversion of heavy compounds, for example compounds having a boiling point above 175°C, into compounds having a boiling point less than or equal to 175°C contained in the hydrocarbon effluent from step f) of fractionation. Other reactions, such as the hydrogenation of olefins and aromatics, hydrodemetallation, hydrodesulfurization, hydrodeazotation, etc., can be carried out.

[0223] Compounds with a boiling point above 175°C have a high BMCI and, compared to lighter compounds, contain more naphthenic, naphtheno-aromatic, and aromatic compounds, thus leading to a higher C / H ratio. This high ratio causes coking in the steam cracker, thus requiring steam cracking furnaces dedicated to this cut. When it is desired to minimize the yield of these heavy compounds (middle distillate cut) and maximize the yield of light compounds (naphtha cut), these compounds can be converted, at least partially, into light compounds by hydrocracking, a cut generally preferred for a steam cracking unit.

[0224] Thus, the process of the invention may comprise a hydrocracking step (g) carried out in a hydrocracking reaction section, employing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed by at least a portion of said hydrocarbon effluent from step (c) and / or by at least a portion of the second hydrocarbon cut comprising compounds having a boiling point above 175°C from step (f) and a gas stream comprising hydrogen, said hydrocracking reaction section being carried out at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and a velocity hourly volume between 0.1 and 10.0 h 1 to obtain a first hydrocracked effluent.

[0225] Thus, said hydrocracking reaction section is advantageously implemented at an average temperature between 250 and 450°C, preferably between 320 and 430°C, at a partial pressure of hydrogen between 1.5 and 20.0 MPa abs., preferably between 3 and 18.0 MPa abs., and at a volumetric rate per hour (WH) between 0.1 and 10.0 h⁻¹, preferably between 0.1 and 5.0 h⁻¹, preferably between 0.2 and 4 h⁻¹. The hydrogen coverage in step g) is advantageously between 80 and 2000 Nm³ of hydrogen per m³ of fresh feed that feeds step a), and preferably between 200 and 1800 Nm³ of hydrogen per m³ of fresh feed that feeds step a). The definitions of mean temperature (WABT), WH and hydrogen cover correspond to those described above.

[0226] Advantageously, said hydrocracking reaction section is implemented at a pressure equivalent to that used in the reaction section of step a) of hydrogenation or step b) of hydrotreating.

[0227] Advantageously, said step (g) is carried out in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrocracking catalysts. When a reactor comprises several catalytic beds, that is to say at least two, preferably between two and ten, preferably between two and five catalytic beds, said catalytic beds are preferably arranged in series in said reactor.

[0228] The hydrocracked effluent can at least partially be recycled in step a) hydrogenation and / or in step b) hydrotreatment and / or in step c) separation. Preferably, it is recycled in step c) separation.

[0229] The hydrocracking step can be carried out in one (step g) or two steps (steps g) and g')). When carried out in two steps, the effluent from the first hydrocracking step g) is separated to obtain a hydrocarbon fraction comprising compounds with a boiling point above 175°C (middle distillate fraction), which is introduced into the second hydrocracking step g') comprising a second dedicated hydrocracking reaction section, different from the first hydrocracking reaction section g). This configuration is particularly suitable when it is desired to produce only a naphtha fraction.

[0230] The second hydrocracking step g') carried out in a hydrocracking reaction section, employing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least a hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of the first hydrocracking effluent from the first hydrocracking step (g) and a gas stream comprising hydrogen, said hydrocracking reaction section being operated at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs., and a volumetric flow rate between 0.1 and 10.0 h⁻¹, to obtain a second hydrocracking effluent. The preferred operating conditions and catalysts used in the second hydrocracking step are those described for the first hydrocracking step. The operating conditions and catalysts used in the two hydrocracking steps may be identical or different.

[0231] Said second hydrocracking step is preferably carried out in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed bed reactor(s) having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, said bed(s) each comprising at least one, and preferably not more than ten, hydrocracking catalyst(s).

[0232] These operating conditions used in the hydrocracking step(s) generally allow for conversions per pass to products having at least 80% by volume of compounds with boiling points of 175°C or lower, preferably lower than 160°C and preferably lower than 150°C, greater than 15% by weight and even more preferably between 20 and 95% by weight. When the process is carried out in two hydrocracking steps, the conversion per pass in the second step is kept moderate in order to maximize selectivity for naphtha cut compounds (having a boiling point of 175°C or lower, in particular between 80°C and 175°C or lower). The conversion per pass is limited by the use of a high recycle ratio on the loop of the second hydrocracking step.This rate is defined as the ratio between the feed flow rate of stage g') and the charge flow rate of stage a) or stage b), preferably this ratio is between 0.2 and 4, preferably between 0.5 and 2.5.

[0233] The hydrocracked effluent from the second hydrocracking step g') can at least partially be recycled in the hydrogenation step a) and / or in the hydrotreating step b) and / or in the separation step c). Preferably, it is recycled in the separation step c).

[0234] The hydrocracking step(s) do not necessarily allow the transformation of all hydrocarbon compounds with a boiling point above 175°C (middle distillate cut) into hydrocarbon compounds with a boiling point below or equal to 175°C (naphtha cut). After the fractionation step f), a more or less significant proportion of compounds with a boiling point above 175°C. To increase conversion, at least a portion of this unconverted fraction can be introduced into a second hydrocracking stage (g'). Another portion can be purged. Depending on the process operating conditions, this purge can be between 0 and 10% by weight of the fraction comprising compounds having a boiling point above 175°C relative to the incoming feed, and preferably between 0.5% and 5% by weight.

[0235] According to the invention, the hydrocracking step(s) operate in the presence of at least one hydrocracking catalyst.

[0236] The hydrocracking catalyst(s) used in the hydrocracking step(s) are conventional hydrocracking catalysts known to those skilled in the art, of a bifunctional type combining an acid function with a hydro-dehydrogenating function and optionally at least one binding matrix. The acid function is provided by large surface area supports (generally 150 to 800 m² / g) exhibiting surface acidity, such as halogenated aluminas (particularly chlorinated or fluorinated), combinations of boron and aluminum oxides, amorphous silica-aluminas, and zeolites. The hydro-dehydrogenating function is provided by at least one metal from group VIB of the periodic table and / or at least one metal from group VIII.

[0237] Preferably, the hydrocracking catalyst(s) comprise a hydro-dehydrogenating function including at least one metal from Group VIII selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, and platinum, and preferably from cobalt and nickel. Preferably, said catalyst(s) also comprise at least one metal from Group VIB selected from chromium, molybdenum, and tungsten, alone or in a mixture, and preferably from molybdenum and tungsten. NiMo, NiMoW, and NiW type hydro-dehydrogenating functions are preferred.

[0238] Preferably, the content of Group VIII metal in the hydrocracking catalyst(s) is advantageously between 0.5 and 15 wt% and preferably between 1 and 10 wt%, the percentages being expressed as a wt% of oxides relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO, respectively.

[0239] Preferably, the content of group VIB metal in the hydrocracking catalyst(s) is advantageously between 5 and 35 wt%, and preferably between 10 and 30 wt%, the percentages being expressed as a wt% of oxides relative to the total weight of the catalyst. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0240] The hydrocracking catalyst(s) may also optionally include at least one promoting element deposited on the catalyst and selected from the group formed by phosphorus, boron and silicon, possibly at least one element from group VIIA (chlorine, fluorine preferred), possibly at least one element from group VIIB (manganese preferred), and possibly at least one element from group VB (niobium preferred).

[0241] Preferably, the hydrocracking catalyst(s) comprise at least one amorphous or poorly crystallized porous mineral matrix of the oxide type selected from aluminas, silicas, silica-aluminas, aluminates, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, clay, alone or in mixture, and preferably aluminas or silica-aluminas, alone or in mixture.

[0242] Preferably, the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina.

[0243] Preferably, the hydrocracking catalyst(s) may also include a zeolite selected from the Y zeolites, preferably from the US Y zeolites, alone or in combination with other zeolites from the beta zeolites, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, alone or in mixtures. Preferably, the zeolite is the USY zeolite alone.

[0244] In the case where said catalyst includes a zeolite, the zeolite content in the hydrocracking catalyst(s) is advantageously between 0.1 and 80% by weight, preferably between 3 and 70% by weight, the percentages being expressed as a percentage of zeolite relative to the total weight of the catalyst.

[0245] A preferred catalyst comprises, and preferably consists of, at least one metal from group VIB and optionally at least one non-noble metal from group VIII, at least one promoting element, preferably phosphorus, at least one zeolite Y and at least one alumina binder.

[0246] An even more preferred catalyst comprises, and is preferably made up of, nickel, molybdenum, phosphorus, a USY zeolite, and possibly also a beta zeolite, and alumina.

[0247] Another preferred catalyst comprises, and is preferably made up of, nickel, tungsten, alumina and silica-alumina.

[0248] Another preferred catalyst comprises, and is preferably made up of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0249] Said hydrocracking catalyst is for example in the form of extrudates.

[0250] In one embodiment, the hydrocracking catalyst used in the second hydrocracking step comprises a hydro-dehydrogenating function including at least one Group VIII noble metal selected from palladium and platinum, alone or in a mixture. The Group VIII noble metal content is advantageously between 0.01 and 5 wt% and preferably between 0.05 and 3 wt%, the percentages being expressed as wt% of oxides (PtO or PdO) relative to the total wt% of the catalyst.

[0251] According to another aspect of the invention, the hydrocracking catalyst further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such a catalyst is often referred to as an "additized catalyst." Generally, the organic compound is chosen from a compound having one or more chemical functions selected from among a carboxyl group, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide, or compounds including a furan ring, or sugars.

[0252] The preparation of catalysts for hydrogenation, hydrotreating, and hydrocracking steps is known and generally includes an impregnation step with Group VIII and Group VIB metals, when present, and possibly phosphorus and / or boron on the support, followed by drying and then possibly calcination. In the case of an additive catalyst, preparation is generally carried out by simple drying without calcination after the introduction of the organic compound. Calcination is understood here as heat treatment under a gas containing air or oxygen at a temperature of 200°C or higher. Before their use in a process step, catalysts are generally subjected to sulfidation to form the active species. The catalyst in step a) may also be a catalyst used in its reduced form, thus implying a reduction step in its preparation.

[0253] The hydrogen-containing gas stream that feeds the selective hydrogenation, hydrogenation, hydrotreating, and hydrocracking reaction section can consist of hydrogen make-up and / or recycled hydrogen, particularly from separation step c). Preferably, an additional hydrogen-containing gas stream is advantageously introduced at the inlet of each reactor, especially those operating in series, and / or at the inlet of each catalytic bed from the second catalytic bed of the reaction section. These additional gas streams are also called cooling streams. They allow for temperature control in the reactor, in which the reactions carried out are generally highly exothermic.

[0254] Said hydrocarbon effluent or hydrocarbon stream(s) thus obtained by treatment according to the process of the invention of a plastic pyrolysis oil, have a composition compatible with the specifications of an inlet feed for a steam cracking unit. In particular, the composition of the hydrocarbon effluent or hydrocarbon stream(s) is preferably such that: - the total content of metallic elements is less than or equal to 10.0 ppm by weight, preferably less than or equal to 2.0 ppm by weight, preferably less than or equal to 1.0 ppm by weight and preferably less than or equal to 0.5 ppm by weight, with: a silicon (Si) content less than or equal to 5.0 ppm by weight, preferably less than or equal to 1 ppm by weight, and preferably less than or equal to 0.6 ppm by weight and / or an iron (Fe) content less than or equal to 200 ppb by weight, - the sulfur content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight, and / or - the nitrogen content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight and preferably less than or equal to 5 ppm by weight and / or - the asphaltene content is less than or equal to 5.0 ppm by weight, and / or - the total chlorine content is less than or equal to 10 ppm by weight, preferably less than 1.0 ppm by weight, and / or - a mercury content less than or equal to 5 ppb by weight, preferably less than 3 ppb by weight, and / or - the content of olefinic compounds (mono- and di-olefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.1% by weight. The contents are given as relative weight concentrations, percentage (%) by weight, part(s) per million (ppm) by weight or part(s) per billion (ppb) by weight, relative to the total weight of the stream considered.

[0255] The process according to the invention therefore makes it possible to treat the pyrolysis oils of plastics to obtain an effluent which can be injected, in whole or in part, into a steam cracking unit. (Optional) heavy metal adsorption step

[0256] Any gaseous effluent and / or any liquid effluent from at least one of the separation steps c), d) or e) or from the fractionation step f) may be subjected to an optional heavy metal adsorption step.

[0257] The gaseous effluents may include, in particular, the gaseous effluent from step c) and / or the gaseous phase containing H2S from step d) and / or the gaseous phase containing NH3 from step e) and / or the gaseous effluent from step f) of fractionation.

[0258] Liquid effluents may include, in particular, the hydrocarbon effluent from step c) and / or the first and / or second hydrocarbon cut from step f).

[0259] The optional adsorption step makes it possible to eliminate or reduce the quantity of metallic impurities, in particular the quantity of heavy metals such as arsenic, zinc, lead, and especially mercury, which may be present in said gaseous and liquid effluents. The metallic impurities, and in particular heavy metals, are present in the feedstock. Certain impurities, particularly those based on mercury, can be transformed in one of the steps of the process according to the invention. Their transformed form is easier to trap. Their elimination or reduction may be necessary in particular when at least part of said gaseous and liquid effluents is intended to be sent, either directly or after having undergone one or more optional additional steps such as the fractionation step f), to a step having strict specifications for metallic impurities, such as a steam cracking step.

[0260] Thus, an optional step of adsorption of a gaseous effluent and / or a hydrocarbon effluent from the process according to the invention is advantageously carried out in particular when at least one of these effluents or the feed includes respectively more than 20 ppb by weight, in particular more than 15 ppb by weight of metallic elements of heavy metals (As, Zn, Pb, Hg, ...), and in particular when at least one of these effluents or the feed includes respectively more than 10 ppb by weight of mercury, more particularly more than 15 ppb by weight of mercury.

[0261] Said optional adsorption step is advantageously carried out at a temperature between 20 and 250°C, preferably between 40 and 200°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 1.0 MPa abs.

[0262] Said optional adsorption step can be implemented by any adsorbent known to those skilled in the art that allows the quantity of such contaminants to be reduced.

[0263] According to one variant, said optional adsorption step is implemented in an adsorption section operated in the presence of at least one adsorbent comprising a porous support and at least one active phase which may be sulfur-based in elemental form, or in the form of metallic sulfide or metallic oxide, or even in metallic form in elemental form.

[0264] The porous support may be chosen from among the families of aluminas, silica-aluminas, silicas, zeolites, and / or activated carbons. Advantageously, the porous support is alumina-based. The specific surface area of ​​the support is generally between 150 and 600 m² / g, preferably between 200 and 400 m² / g, and even more preferably between 150 and 320 m² / g. The specific surface area of ​​the adsorbent is measured by the BET method as described above.

[0265] The active phase is sulfur-based in elemental form, or in the form of a metallic sulfide or metal oxide, or even in elemental metallic form. Preferably, the active phase is in the form of a metallic sulfide, in particular a sulfide of a metal from the group selected from copper, molybdenum, tungsten, iron, nickel or cobalt.

[0266] Advantageously, the active phase of the adsorbent comprises between 1 and 70% by weight of sulfur relative to the total weight of the adsorbent, preferably between 2 and 25% and most preferably between 3 and 20%.

[0267] Advantageously, the proportion by weight of metal in relation to the total weight of the adsorbent is generally between 1 and 60%, preferably between 2 and 40%, preferably between 5 and 30%, most preferably between 5 and 20%.

[0268] The residence time in the adsorption section is generally between 1 and 180 minutes.

[0269] Said adsorption section may comprise one or more adsorption columns. When the adsorption section comprises two adsorption columns, one operating mode may be a so-called "swing" mode, in which one of the columns is in operation, while the other column is in reserve. Another operating mode is to have at least two columns operating in series in a switchable mode.

[0270] Preferably, said adsorption section comprises an adsorption column for the gaseous effluent(s) and an adsorption column for the liquid effluent(s). Step h) of steam cracking (optional)

[0271] The hydrocarbon effluent from the separation step c), or at least one of the two liquid hydrocarbon stream(s) from the optional step f), may be sent in whole or in part to a steam cracking step h).

[0272] Advantageously, the gaseous effluent(s) from step c) of separation and / or f) of fractionation and containing ethane, propane and butane, may, in whole or in part, also be sent to step h) of steam cracking.

[0273] Said steam cracking step h) is advantageously carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C, preferably between 750 and 850°C, and at a pressure between 0.05 and 0.3 MPa relative. The residence time of the hydrocarbon compounds is generally less than or equal to 1.0 second (denoted s), preferably between 0.1 and 0.5 s. Advantageously, steam is introduced upstream of the optional steam cracking step h) and after the separation step c) (or fractionation step f)). The quantity of water introduced, advantageously in the form of steam, is advantageously between 0.3 and 3.0 kg of water per kg of hydrocarbon compounds entering step h).Preferably, the optional step h) is carried out in several pyrolysis furnaces in parallel in order to adapt the operating conditions to the different feeds supplying step h), particularly those from step f), and also to manage the decoking times of the tubes. A furnace comprises one or more tubes arranged in parallel. A furnace can also refer to a group of furnaces operating in parallel. For example, a furnace may be dedicated to cracking the hydrocarbon fraction comprising compounds with a boiling point less than or equal to 175°C.

[0274] The effluents from the various steam cracking furnaces are generally recombined before separation to form a single effluent. It is understood that step h) of steam cracking includes the steam cracking furnaces but also the substeps associated with steam cracking that are well known to those skilled in the art. These substeps may include, in particular, heat exchangers, columns and catalytic reactors, and recirculation to the furnaces. A column generally allows the effluent to be fractionated in order to recover at least a light fraction comprising hydrogen and compounds having 2 to 5 carbon atoms, a fraction comprising pyrolysis gasoline, and possibly a fraction comprising pyrolysis oil.Columns are used to separate the different components of the light fractionation fraction in order to recover at least one ethylene-rich cut (C2 cut), one propylene-rich cut (C3 cut), and possibly one butene-rich cut (C4 cut). Catalytic reactors are used, in particular, to perform hydrogenation of the C2, C3, and even C4 cuts, as well as pyrolysis gasoline. Saturated compounds, especially those with 2 to 4 carbon atoms, are advantageously recycled to steam cracking furnaces to increase overall olefin yields.

[0275] This steam cracking step (h) yields at least one effluent containing olefins comprising 2, 3, and / or 4 carbon atoms (i.e., C2, C3, and / or C4 olefins), at satisfactory levels, in particular greater than or equal to 30 wt%, especially greater than or equal to 40 wt%, or even greater than or equal to 50 wt% of total olefins comprising 2, 3, and 4 carbon atoms relative to the weight of the steam cracking effluent considered. These C2, C3, and C4 olefins can then be advantageously used as polyolefin monomers.

[0276] According to a preferred embodiment of the invention, the process for treating a feed comprising a plastic pyrolysis oil preferably comprises the following sequence of steps, and preferably in the given order:

[0277] - b) hydrotreating, c) separation / washing and d) separation of H2S with recycling of H2S in step b), and e) separation of NH3

[0278] - a) hydrogenation, b) hydrotreating, c) separation / washing and d) se H2S preparation with H2S recycling in step a) and / or b), and e) NH3 separation

[0279] - a) hydrogenation, b) hydrotreating, c) separation / washing and d) se H2S preparation with H2S recycling in step a) and / or b), e) NH3 separation and f) fractionation

[0280] - a) hydrogenation, b) hydrotreating, c) separation / washing and d) se H2S preparation with H2S recycling in step a) and / or b), e) NH3 separation and f) fractionation

[0281] and introduction of the hydrocarbon cut comprising compounds having a boiling point above 175°C in step g) of hydrocracking, the hydrocracking effluent being recycled in step c).

[0282] All embodiments may include and preferably consist of in addition to a pretreatment step aO).

[0283] All embodiments may include and preferably consist of in addition to a step h) of steam cracking. Analytical methods used

[0284] The analytical methods and / or standards used to determine the characteristics of the various flows, in particular the load to be treated and the effluents, are known to those skilled in the art. They are listed below for information purposes. Other methods considered equivalent may also be used, including equivalent IP, EN, or ISO methods:

[0285] [Tables 1] Description Methods Density @15°C ASTM D4052 Sulfur Content ISO 20846 Nitrogen Content ASTM D4629 Acid Value ASTM D664 Bromine Number ASTM DI 159 Diolefin Content from Maleic Anhydride Value MAV Method (1) Oxygen Content Combustion + Infrared Paraffin Content UOP990-11 Naphthenes and Olefins Content UOP990-11 Aromatics Content UOP990-11 Halogen Content ASTM D7359 Chloride Content ASTM D7536 Metal Content: ASTM D5185 P Fe Si Na B Simulated Distillation ASTM D2887

[0286] (1) MAV method described in the article: C. Lôpez-Garcla et al., Near Infrared Mo- nitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68 LIST OF FIGURES

[0287] Mention of the elements referenced in Figures 1 to 2 allows for a better understanding of the invention, without the latter being limited to the particular embodiments illustrated in Figures 1 to 2. The different embodiments presented can be used alone or in combination with each other, without limitation of combination. [Fig 1]

[0288] Figure 1 shows a diagram of a particular embodiment of the process of the present invention, comprising: - a step a) of hydrogenation (optional) of a hydrocarbon feed 1 from the pyrolysis of plastics in the presence of a hydrogen-rich gas 2 and possibly an amine supplied by the stream 3 and possibly a sulfurizing agent by the stream 4 (especially at the beginning of the cycle);

[0289] -a step b) hydrotreatment fed by the hydrocarbon effluent 5 from step a) hydrogenation if present and by a flow of a hydrogen-rich gas 6;

[0290] -a separation step c) fed by the effluent 7 from the hydrotreatment step b) and in the presence of an aqueous solution 10 to obtain at least a gaseous effluent 11, a first aqueous effluent 12 containing H2S, HCl and NH3 and a hydrocarbon effluent 13;

[0291] - a step d) of separating the H2S contained in the first aqueous effluent 12 from preferably by stripping with a stream containing water vapor 19 allowing to obtain a gaseous phase containing H2S 20 and a second aqueous effluent 21, said gaseous phase containing H2S is at least partly recycled upstream of step a) and / or step b), preferably upstream of step a) when it is present. This recycling of the phase containing H2S 20 makes it possible to maintain the catalysts of steps a) and / or b) in sulfide form and thus to reduce the input of sulfurizing agent 4;

[0292] - a step e) of separating the NH3 contained in the second aqueous effluent 21 from Preference for stripping with a stream containing water vapor 19, allowing the production of a gaseous phase containing NH3 22 and a third aqueous effluent 23. [Fig 2]

[0293] Figure 2 shows a diagram of another particular embodiment of the process of the present invention which is based on the diagram in Figure 1. This diagram includes a step c) carried out in two stages, then a step f) of fractionation and a step g) of hydrocracking in addition.

[0294] Step a) hydrogenation and step b) hydrotreating are carried out as described in [Fig. 1]. Step c) separation, carried out in two stages, includes in particular:

[0295] - a step cl) of separation of the hydrotreated effluent 7 carried out at high pressure and high temperature (HHPS) to obtain at least one gaseous effluent 8, and one liquid effluent 9 of which a part 9a can be recycled upstream of step a) or upstream of step b) (not shown),

[0296] - a separation step c2) carried out at high pressure and low temperature (HPLS) and supplied by the gaseous effluent 8 and the other part of the liquid effluent 9b from step cl) and an aqueous solution 10 and enabling the production of at least one gaseous effluent 11 comprising hydrogen, one aqueous effluent 12 containing dissolved salts and dissolved H2S and NH3, and one hydrocarbon effluent 13;

[0297] Step d) of H2S separation and step e) of NH3 separation are carried out as described in [Fig. 1]. Recycling of the phase containing H2S 20 is carried out in the same way. It can also be at least partially recycled in step g) of hydrocracking. Optionally, a step f) of fractionation of the hydrocarbon effluent 13 is carried out to obtain at least one gaseous effluent 14, a first hydrocarbon cut 15 comprising compounds having a boiling point less than or equal to 175°C (naphtha cut) and a second hydrocarbon cut 16 comprising compounds having a boiling point greater than 175°C (middle distillates cut).

[0298] Following step f), a portion of the first hydrocarbon cut 15, comprising compounds with a boiling point of 175°C or lower, can be sent to a steam cracking process (not shown). Another portion of the first hydrocarbon cut 15 can feed into step a) hydrogenation and / or step b) hydrotreating (recycling not shown).

[0299] In [Fig.2], at least part of the second hydrocarbon cut 16 comprising compounds having a boiling point above 175°C from step f) feeds a hydrocracking step g) which is carried out in at least one fixed bed reactor comprising at least one hydrocracking catalyst and is supplied with hydrogen 17. The hydrocracking effluent 18 can be recycled between separation steps cl) and c2) or upstream of separation step c) (not shown).

[0300] Instead of injecting the amine 3 flux into the inlet of step a) hydrogenation, it is possible to inject it into the inlet of step b) hydrotreating, into the inlet of step c) separation, into the inlet of step g) hydrocracking when it is present, or not to inject it, depending on the characteristics of the feed.

[0301] Only the main stages, with the principal flows, are shown in Figures 1 and 2, to facilitate a better understanding of the invention. It is understood that all the equipment necessary for operation is present (tanks, pumps, heat exchangers, furnaces, columns, etc.), even if not shown. It is also understood that hydrogen-rich gas flows (make-up or recycle), as described above, can be injected at the inlet of each reactor or catalytic bed or between two reactors or two catalytic beds. Methods well known to those skilled in the art for hydrogen purification and recycling can also be implemented. EXAMPLES Example 1 (according to the invention)

[0302] The charge 1 treated in the process with a flow rate of 10000 kg / h (10 T / h) is a plastics pyrolysis oil (i.e. comprising 100% by weight of said plastics pyrolysis oil) having the characteristics indicated in Table 2.

[0303] Table 2: Load characteristics

[0304] [Tables2] Description / Methods ASTM D4052 Unit Pyrolysis Oil Density @ 15°C g / cm3 0.845 Sulfur Content ISO 20846 ppm wt 170 Nitrogen Content ASTM D4629 ppm wt 2264 Acid Value ASTM D664 mgKOK / g 3.95 Bromine Value ASTM DI 159 g Br2 / 100g 90 Diolefin Content from Maleic Anhydride Value MAV Method (i) % wt 36 Elemental Oxygen Content ASTM D5622 % wt 1.0 Paraffin Content UOP990-11 % wt 19 Naphthene Content UOP990-11 % wt 7 Olefin Content UOP990-11 % wt 31 Aromatic Content UOP990-11 % by weight 43 Halogen content ASTM D7359 ppm by weight 400 Asphaltene content IFP 9313 ppm by weight 380 Metal content ASTM D5185 P ppm by weight 46 Fe ppm by weight 3 Si ppm by weight 130 Na ppm by weight 2.5 B ppm by weight 5 As ppb by weight 200 Hg ppb by weight 20 Simulated Distillation ASTM D2887 0% °C 45 10% °C 94 30% °C 135 50% °C 180 70% °C 250 90% °C 394 100% °C 550

[0305] (1) MAV method described in the article: C. Lôpez-Garcla et al., Near Infrared Mo- nitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68

[0306] The charge 1 is subjected to a step a) of hydrogenation carried out in a fixed bed reactor and in the presence of hydrogen 2 and a NiMo on alumina type hydrogenation catalyst under the conditions indicated in Table 3.

[0307] Table 3: Conditions of step a) of hydrogenation

[0308] [Tables3] Reactor inlet temperature °C 290 Reactor outlet temperature °C 320 Average temperature (WABT) °C 305 Partial pressure of hydrogen MPa abs 6.7 H2 / HC (Volume coverage of hydrogen relative to feed volume) Nm3 / m3 300 WH (Volume flow rate of feed / volume of catalysts) h1 0.8

[0309] The conditions indicated in Table 3 correspond to cycle start conditions and the average temperature (WABT) is increased by 1°C per month in order to compensate for catalytic deactivation.

[0310] At the end of step a) of hydrogenation, the conversion rates (= (initial concentration - final concentration) / initial concentration) observed are shown in Table 4.

[0311] Table 4: Species conversions during step a) hydrogenation

[0312] [Tables4] Diolefin conversion rate % >60 Olefin conversion rate % >60 Silicon retention % >75

[0313] The effluent 5 from step a) of hydrogenation is directly subjected, without separation, to a step b) of hydrotreatment carried out in a fixed bed and in the presence of hydrogen and a NiMo on alumina type hydrotreatment catalyst under the conditions presented in Table 5.

[0314] Table 5: Conditions of step b) of hydrotreatment

[0315] [Tables5] Average Water Treatment Temperature (WABT) °C 325 Partial Pressure of Hydrogen MPa abs 6.5 H2 / HC (Volume coverage of hydrogen relative to feed volume) Nm3 / m3 400 WH (Volume flow rate of feed / volume of catalysts) h1 0.5

[0316] The conditions indicated in Table 5 correspond to start-of-cycle conditions and the average temperature (WABT) is increased by 1°C per month in order to compensate for catalytic deactivation.

[0317] The effluent 7 from hydrotreatment step b) is subjected to a separation step c): a water stream 10 is injected into the effluent from hydrotreatment step b); the mixture is then treated in an acid gas scrubbing column and separator vessels to obtain a gas fraction and a liquid effluent. The yields of the different fractions obtained after separation are shown in Table 6 (the yields correspond to the ratios of the mass quantities of the different products obtained to the mass of feed upstream of step a), expressed as a percentage and denoted % w / w).

[0318] Table 6: Yields of the different products obtained after separation

[0319] [Tables] Gas fraction (NH3 + H2S + H2O + C1-C4) % m / m 2.42 Liquid fraction % m / m 99.31

[0320] All or part of the liquid fraction obtained can then be valorized in a steam cracking step in order to form olefins which can be polymerized in order to form recycled plastics.

[0321] The pyrolysis oil charge contains very little sulfur (170 ppm by weight). This sulfur The sulfur-containing molecules are hydrogenated in the reaction section and transformed into H₂S. This H₂S, in the form of partial pressure of H₂S (ppH₂S) in the reactor, contributes to maintaining the sulfide phase of the NiMo catalysts on alumina. However, the ppH₂S obtained with this sulfur content in the feed (170 ppm wt) is insufficient to maintain the catalysts in the sulfide phase throughout the cycle. This results in rapid deactivation of catalyst activity if no action is taken. It is therefore necessary to add H₂S to the reaction system to achieve a sufficient ppH₂S. This addition of H₂S can be done by injecting it into the dimethyl disulfide pyrolysis oil (DMDS) feed at the unit inlet. DMDS decomposes easily upon contact with the catalyst into CH4 and H2S, thus generating sufficient ppü2S to maintain the catalysts in sulfide form.This approach results in high DMDS consumption, which is detrimental to the economics of the process.

[0322] Another method of the invention is to recover the H2S which is discharged in the aqueous effluent by means of a double stripping of this aqueous effluent and to reinject this H2S at the inlet of the unit by dissolution in the pyrolysis oil feed.

[0323] The injection of DMDS and / or the recycling of H2S at the unit inlet can serve both to maintain sufficient ppü2S in the reaction system and to neutralize all the NH3 produced by the hydrogenation of nitrogen molecules. Indeed, H2S reacts with NH3 to form ammonium sulfides, which are almost entirely washed away and transferred to the aqueous effluent (stream 12), thus releasing the gas stream at the outlet of the ammonia stabilization column (stream 11). This ammonia-free gas stream can then be sent directly to the steam cracker to maximize olefin production.

[0324] The advantage of recycling an H2S stream compared to injecting DMDS, whether in the context of maintaining a sufficient ppü2S or in the case of delivering a gas stream free of its ammonia, is therefore to save the quantity of DMDS throughout the cycle.

[0325] Table 7 shows four operating cases.

[0326] Case 1: Single acid water stripper and DMDS injection only to maintain a sufficient ppü2S to keep the catalysts in the sulfide phase.

[0327] Case 2: Double acid water stripper to recycle at the unit inlet a predominantly H2S stream from the head of the first stripping column only to maintain a sufficient ppü2S to keep the catalysts in the sulfide phase. This case is consistent with the invention.

[0328] Case 3: Simple acid water stripper and DMDS injection to maintain sufficient ppü2S to keep the catalysts in the sulfide phase and also to neutralize all the NH3 and deliver an NH3-free gas stream

[0329] Case 4: Double acid water stripper to recycle at the unit inlet a predominantly H2S stream from the head of the first stripping column to maintain a sufficient ppH2S to keep the catalysts in sulfide phase and also to neutralize all the NH3 and deliver an NH3-free gas stream. This case is in accordance with the invention.

[0330] It can be noted that the invention saves 19 kg / h of DMDS when it comes to maintaining a minimum ppH2S to keep the catalysts in sulfide form.

[0331] It can also be noted that the invention allows an even greater saving, namely 65 kg / h (75 - 10 = 65 kg / h) of DMDS saved to deliver an ammonia-free gas flow.

[0332] Table 7: Operating Cases

[0333] [Tables?] Case 1 Case 2 Case 3 Case 4 Single acid water stripper with minimum ppH2S Double acid water stripper with minimum ppH2S Single acid water stripper with NH3-free gas flow Double acid water stripper with NH3-free gas flow ppH2S at the outlet of the HDT reactor bar a 0.02 (0.002 MPa) 0.02 (0.002 MPa) 0.21 (0.021 MPa) 0.21 (0.021 MPa) DMDS injection flow rate kg / h 19 0 75 10 DMDS gain kg / h - 19 - 65 Stabilization column operating conditions Top column pressure barg 7.1 (0.71 MPa) Bottom column pressure barg 7.3 (0.73 MPa) Inlet charge temperature °C 160 Number of theoretical plates 10 Heat flux of the Reboiler Gcal / h 0.55 Operating conditions of the H2S Stripping column Top pressure barg N / A 9 (0.9 MPa) N / A 9 (0.9 MPa) Bottom pressure barg 9.1 (0.91 MPa) 9.1 (0,91 MPa) Inlet charge temperature °C 135 130 Number of theoretical trays - 12 12 Stripping steam flow rate kg / h 285 303 Operating conditions of the NH3 Stripping column Top pressure barg N / A 2.4 N / A 2.4 , (0.24 MPa) (0.24 MPa) Bottom pressure of barg column 2.6 (0.26 MPa) 2.6 (0.26 MPa) Inlet charge temperature °C 124 126 Number of theoretical trays - 15 15 Stripping steam flow rate kg / h 535 538 Operating conditions of the Simple Stripping Column (H2S & NH3) Top pressure of barg column 2.4 (0.24 MPa) N / A 2.4 (0.24 MPa) N / A Bottom pressure of barg column 2.5 (0.25 MPa) Inlet charge temperature °C 94 Number of theoretical trays - 15 Stripping steam flow rate kg / h 435 Stabilization column overhead gas flow rate kg / h 177 169 179 Stabilization column overhead gas composition h2 %mol 29.3 31.7 26.4 h2s %mol NIL 0.2 1.8 nh3 %mol 9.6 9.8 NIL h2o %mol 1.4 1.4 1.4 Cl %mol 33.8 29.9 46.7 C2 %mol 6.9 7.3 6.8 C3 %mol 3.9 4.0 3.7 C4 %mol 10.7 11.1 10.1 C5+ %mol 4.5 4.4 3.1 Flow rate of H2S-rich gas at the top of the H2S stripping column (kg / h) N / A 14 N / A Composition of H2S-rich gas at the top of the H2S stripping column: h2s %mol N / A 92.2 N / A nh3 %mol 0.05 h2o %mol 7.74 Flow rate of acidic gas at the top of the acid water stripping column (kg / h) 40 22 103 Composition of acidic gas at the top of the NH3 stripping column (or simple stripping column): h2s %mol 24.5 2.7 32.7 nh3 %mol 44.3 66.1 35.7 h2o %mol 31.2 31.3 31.6 Flow rate of stripped water (kg / h) 2,553 2,996 2,551 Composition of stripped water: H2O % by weight 99.9 99.9 99.9 nh3 ppm weight <30 <30 <30 h2s ppm weight <5 <5 <5 Hydrocarbon ppm weight Trace Trace Trace

Claims

Demands

1. A process for treating a feedstock comprising a plastics pyrolysis oil, comprising: a) optionally a hydrogenation step carried out in a hydrogenation reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst, said hydrogenation reaction section being fed at least by said feedstock and a gas stream comprising hydrogen, said hydrogenation reaction section being carried out at an average temperature between 140 and 400°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric rate between 0.1 and 10.0 h1, to obtain a hydrogenated effluent, b) a hydrotreating step carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst,said hydrotreating reaction section being fed at least by the feed or said hydrogenated effluent from step a) and a gaseous stream comprising hydrogen, said hydrotreating reaction section being operated at an average temperature between 250 and 430°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and an hourly volumetric velocity between 0.1 and 10.0 h*, to obtain a hydrotreated effluent, c) a separation step, fed by the hydrotreated effluent from step b) and possibly by the hydrocracked effluent from step g) and an aqueous solution to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent, d) a step of separating the H2S contained in the first aqueous effluent to obtain a gaseous phase containing the H2S and a second aqueous effluent, said gaseous phase containing the H2S is at least partly recycled upstream of step a) and / or step b) and / or step g),e) a step of separating the NH3 contained in the second aqueous effluent to obtain a gaseous phase containing NH3 and a third aqueous effluent, said gaseous phase containing NH3 being optionally at least partially recycled upstream of step a) and / or step b) and / or step g), f) optionally a step of fractionating all or part of, the hydrocarbon effluent from step c), to obtain at least one gaseous effluent and at least one first hydrocarbon cut comprising compounds having a boiling point less than or equal to 175°C and a second hydrocarbon cut comprising compounds having a boiling point greater than 175°C, g) optionally a hydrocracking step carried out in a hydrocracking reaction section, employing at least one fixed bed having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed by at least a portion of said hydrocarbon effluent from step c) and / or by at least a portion of the second hydrocarbon cut comprising compounds having a boiling point greater than 175°C from step f) and a gaseous stream comprising hydrogen,said hydrocracking reaction section being implemented at an average temperature between 250 and 450°C, a partial pressure of hydrogen between 1.5 and 20.0 MPa abs. and an hourly volumetric rate between 0.1 and 10.0 h 1 to obtain a first hydrocraced effluent.

2. A process according to any one of the preceding claims comprising the hydrogenation step a).

3. A method according to any one of the preceding claims comprising the fractionation step f).

4. A method according to any one of the preceding claims comprising the hydrocracking step g).

5. A method according to any one of the preceding claims wherein step d) of separating the H2S contained in the first aqueous effluent is carried out by stripping said effluent with a stream containing water vapor at a pressure between 0.5 and 1 MPa and a temperature between 80 and 150°C.

6. A method according to any one of the preceding claims wherein step e) of separating the NH3 contained in the second aqueous effluent is carried out by stripping said effluent with a stream containing water vapor at a pressure between 0.1 and 0.5 MPa and a temperature between 80 and 150°C.

7. A process according to any one of the preceding claims, wherein the separation step (c) comprises the following steps: (c) a separation step, fed by the hydrotreated effluent from step (b), said step being operated at a temperature between 200 and 450°C and at a pressure substantially the same as the pressure of step b) to obtain at least one gaseous effluent and one liquid effluent, part of which may be recycled upstream of step a) and / or step b), c2) a separation step, fed by the gaseous effluent from step c1) and another part of the liquid effluent from step c1) and an aqueous solution, said step being carried out at a temperature between 20 and below 200°C, and at a pressure substantially the same as or below the pressure of step b), to obtain at least one gaseous effluent, a first aqueous effluent and a hydrocarbon effluent,

8. A process according to any one of the preceding claims, comprising at least one pretreatment step aO) of the feed comprising a plastic pyrolysis oil, optionally mixed with the hydrocarbon effluent from step c), said pretreatment step being carried out upstream of step a) and / or upstream of step b) and comprising a filtration step and / or a centrifugation step and / or an electrostatic separation step and / or a washing step using an aqueous solution and / or an adsorption step and / or a selective hydrogenation step.

9. A process according to any one of the preceding claims, wherein the hydrocarbon effluent from the separation step c), or at least one of the two liquid hydrocarbon cuts from step f), is sent in whole or in part to a steam cracking step h) carried out in at least one pyrolysis furnace at a temperature between 700 and 900°C and at a pressure between 0.05 and 0.3 MPa relative.

10. A process according to any one of the preceding claims wherein said NH3-containing gaseous phase from step e) is at least partly recycled upstream of step a) and / or step b) and / or step g).

11. A method according to any one of the preceding claims wherein a stream containing a nitrogen compound and / or a sulfur compound is injected upstream of step a) and / or upstream of step b).

12. A process according to any one of the preceding claims wherein said hydrogenation catalyst comprises a support selected from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof and a hydro-dehydrogenating function comprising either at least one element of Group VIII and at least one element of Group VIB, or at least one element of Group VIII.

13. A process according to any one of the preceding claims wherein said hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof, and a hydro-dehydrogenating function comprising at least one element from group VIII and / or at least one element from group VIB.

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

15. A process according to any one of the preceding claims, wherein said hydrocracking catalyst comprises a support selected from halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites and a hydro-dehydrogenating function comprising at least one metal from group VIB selected from chromium, molybdenum and tungsten, alone or in mixture, and / or at least one metal from group VIII selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

16.

17. Product obtained by the process according to any one of claims 1 to 15. Product according to claim 16, which comprises, relative to the total weight of the product: - a total metallic content of less than or equal to 10.0 ppm by weight, - of which an iron content of less than or equal to 200 ppb by weight, and / or - a silicon content of less than or equal to 5.0 ppm by weight, and / or - a sulfur content of less than or equal to 100 ppm by weight, and / or - a nitrogen content of less than or equal to 100 ppm by weight, and / or - a chlorine content less than or equal to 10 ppm by weight, and / or - a mercury content less than or equal to 5 ppb by weight.

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