Optimized method for processing plastic pyrolysis oils for improving their use

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for treating a plastic pyrolysis oil to obtain a hydrocarbon effluent that can be recovered, for example, by being at least partially integrated directly into a naphtha or diesel pool 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, in order to remove at least some of the impurities, in particular olefins (mono- and di-olefins), metals, especially silicon, and halogens, especially chlorine, that said feedstock may contain in relatively large quantities, and to hydrogenate the feedstock so that it can be recovered.

[0002] The process according to the invention thus makes it possible to treat plastic pyrolysis oils to obtain an effluent that can be injected, in whole or in part, into a steam cracking unit. The process according to the invention therefore makes it possible to valorize plastic pyrolysis oils, while reducing coke formation and thus the risks of clogging and / or premature loss of activity of the catalyst(s) used in the steam cracking unit, and reducing the risk of corrosion. PREVIOUS TECHNIQUE

[0003] Plastics collected and sorted through recycling programs can undergo pyrolysis to produce, 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.

[0004] Another way to valorize plastic pyrolysis oils could be by using them as feedstock in a steam cracking unit to (re)create olefins, which are monomers that make up 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 its 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 sources such as household waste.As a result, the oils produced by the pyrolysis of plastic waste contain many impurities, particularly diolefins, metals (especially silicon), halogenated compounds (including chlorine-based compounds), heteroatoms such as sulfur, oxygen, and nitrogen, and insolubles, often at high levels incompatible with steam cracking units or downstream units, such as polymerization and selective hydrogenation processes. These impurities can cause operability problems, including corrosion, coking, catalytic deactivation, and incompatibility issues with the target polymers. The presence of diolefins can also lead to pyrolysis oil instability, characterized by gum formation. This phenomenon is generally mitigated by proper feedstock storage.Gums and insolubles that may be present in pyrolysis oil can cause clogging problems in the processes.

[0005] Furthermore, during the steam cracking stage, the yields of light olefins sought for petrochemicals, particularly ethylene and propylene, are highly dependent on the quality of the feedstocks sent to the cracker. The BMCI (Bureau of Mines Correlation Index) is often used to characterize hydrocarbon fractions. Generally, light olefin yields increase when the paraffin content increases and / or when the BMCI decreases. Conversely, yields of undesirable heavy compounds and / or coke increase when the BMCI increases.

[0006] Document WO 2018 / 055555 proposes a comprehensive, very general, and relatively complex plastic waste recycling process, from the initial pyrolysis stage 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, between 260 and 300°C; a separation stage of the hydrotreating effluent; and then a hydrodelakylation stage of the separated heavy effluent, preferably at a high temperature, for example, between 260 and 400°C.

[0007] Document WO 2014 / 001632 discloses a process for treating biomass that may contain polymers, comprising a two-step prehydrogenation step; a hydroprocessing step including hydroisomerization, hydrotreating, hydrodearomatization, and / or hydrocracking reactions; a separation step into a gaseous phase, an aqueous phase, and a hydrocarbon effluent; and a fractionation step to obtain diesel and gasoline-type fractions. Documents US 2016 / 264885 A1, WO 2016 / 142809 A1, and US 3,492,220 A also describe a process according to the prior art.

[0008] The present invention aims to overcome these drawbacks and contribute to the recycling of plastics, by proposing a process for treating an oil from the pyrolysis of plastics to purify and hydrotreat it in order to obtain a hydrocarbon effluent with a reduced content of impurities and therefore usable, either directly in the form of naphtha cut and / or diesel cut, or having a composition compatible with a charge of a steam cracking unit and allowing to obtain improved yields of light olefins during the steam cracking step, while in particular reducing the risks of clogging during the treatment steps of plastic pyrolysis oils, such as those described in the prior art, and the formation of coke in large quantities and / or the risks of corrosion encountered during subsequent step(s), for example during the steam cracking step of plastic pyrolysis oils. SUMMARY OF THE INVENTION

[0009] The invention relates to a process for treating a charge comprising a plastic pyrolysis oil, as defined in the claims.

[0010] An advantage of the process according to the invention is to purify an oil from the pyrolysis of plastic waste of at least part of its impurities which makes it possible to hydrogenate it and thus to be able to valorize it in particular by incorporating it directly into a fuel pool or by making it compatible with a treatment in a steam cracking unit in order to obtain in particular light olefins with increased yields which can be used as monomers in the manufacture of polymers.

[0011] 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.

[0012] 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 selective hydrogenation units. The elimination of at least some of the impurities from the oils resulting from the pyrolysis of plastic waste will also broaden the range of applications for the target polymers, as incompatibilities in use are reduced.

[0013] The invention also has the advantage of contributing to plastic recycling and the preservation of fossil resources by enabling the recovery of oils from their pyrolysis. It allows for the purification and hydrotreating of these oils, which can then be introduced into a steam cracker to obtain olefins and thus remanufacture polymers. The process also makes it possible to obtain naphtha and / or diesel fractions from feedstocks containing plastic pyrolysis oils. These fractions could then be directly integrated by the refiner into the naphtha and / or diesel pools obtained from crude oil refining, respectively. DESCRIPTION OF IMPLEMENTATION METHODS

[0014] 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 from collection and sorting channels. It comprises, in particular, a mixture of hydrocarbon compounds, notably paraffins, mono- and / or diolefins, naphthenes, and aromatics, these hydrocarbon compounds preferably having a boiling point below 700°C and more preferably below 550°C. The plastic pyrolysis oil may, and most often does, further comprise impurities such as metals, particularly silicon and iron, and halogenated compounds, particularly chlorinated compounds.These impurities can be present in plastic pyrolysis oils at high concentrations, for example, up to 350 ppm by weight, or even 700 ppm by weight or 1000 ppm by weight of halogenated elements from halogenated compounds, and up to 100 ppm by weight or 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 metallic or semi-metallic metals or 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 10000 ppm weight of heteroelements and preferably less than 4000 ppm weight of heteroelements.

[0015] According to the present invention, the pressures are absolute pressures, also noted as abs., and are given in absolute MPa (or MPa abs.).

[0016] 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 within the described range of values. If this were not the case, and the limit values ​​were not included within the described range, this clarification will be provided by the present invention. 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 preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0017] In the following, specific and / or preferred embodiments of the invention may be described. They may be implemented separately or in combination, without limitation as to whether they can be combined, when technically feasible.

[0018] The invention relates to a process for treating a charge comprising a plastic pyrolysis oil, according to claim 1. The charge

[0019] The feedstock of the process according to the invention comprises at least one plastic pyrolysis oil. This feedstock may consist solely of plastic pyrolysis oil(s). Preferably, this feedstock comprises at least 50% by weight, and more preferably between 75% and 100% by weight, of plastic pyrolysis oil, i.e., preferably between 50% and 100% by weight, and more preferably between 70% and 100% by weight of plastic pyrolysis oil. The feedstock of the process according to the invention may include, among other things, one or more plastic pyrolysis oils, a conventional petroleum feedstock, or a feedstock derived from biomass conversion, which is then co-treated with the plastic pyrolysis oil of the feedstock.

[0020] The pyrolysis oils from the plastics in said feedstock comprise hydrocarbon compounds and impurities such as, in particular, mono- and / or di-olefins, metals, notably silicon and iron, halogenated compounds, notably chlorinated compounds, heteroelements supplied by sulfur compounds, oxygenated compounds, and / or nitrogenous compounds. These impurities are often present at high concentrations, for example, up to 350 ppm by weight, or even 700 ppm by weight or 1000 ppm by weight of halogenated elements, and up to 100 ppm by weight, or even 200 ppm by weight of metallic or semi-metallic elements.

[0021] The said feed comprising a plastics pyrolysis oil can advantageously be pretreated in an optional pretreatment step a0), prior to the selective hydrogenation step a), to obtain a pretreated feed which feeds the step a). This optional pretreatment step a0) makes it possible to reduce the quantity of contaminants, in particular the quantity of silicon, possibly present in the feed comprising a plastics pyrolysis oil.Thus, an optional pretreatment step a0) of the feed comprising a plastic pyrolysis oil is advantageously carried out, particularly when said feed comprises more than 50 ppm by weight, especially more than 20 ppm by weight, more particularly more than 10 ppm by weight, or even more than 5 ppm by weight, of metallic elements, and particularly when said feed comprises more than 20 ppm by weight of silicon, more particularly more than 10 ppm by weight, or even more than 5 ppm by weight, and even more particularly more than 1.0 ppm by weight of silicon. This optional pretreatment step a0) may also include a filtration step to remove any solid impurities.

[0022] The optional pretreatment step a0) is carried out prior to the selective hydrogenation step a) in an adsorption section operated in the presence of at least one adsorbent, preferably having a specific surface area greater than or equal to 100 m² / g, and / or in a solid / liquid separation section, for example, a filtration section. The optional pretreatment step a0) is fed with the feedstock comprising a plastic pyrolysis oil and is carried out at a temperature between 0 and 150°C, preferably between 5 and 100°C, and at a pressure between 0.15 and 10.0 MPa abs, preferably between 0.2 and 1.0 MPa abs. Preferably, the optional pretreatment step a0) incorporates at least one adsorption section.The adsorption section is advantageously 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 measured by the BET method, that is, the specific surface area determined by nitrogen adsorption according to ASTM D 3663-78, based on the Brunauer-Emmett-Teller method described in *The Journal of the American Chemical Society*, 6Q, 309 (1938). Advantageously, the adsorbent comprises less than 1% by weight of metallic elements, and 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.

[0023] The adsorption section of optional step a0) comprises at least one adsorption column, preferably 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" mode, in which one of the columns is in operation, while the other column is in reserve. When the adsorbent in the in-operation column is depleted, that column is isolated while the reserve column is brought into operation. The depleted adsorbent can then be regenerated. in situ and / or replaced with fresh absorbent so that the column containing it can be put back in line once the other column has been isolated.

[0024] Another operating mode is to have at least two columns operating in series. When the absorbent in the first column is worn out, this first column is isolated and the worn absorbent is either regenerated in situor replaced with fresh absorbent. The column is then returned to the last position, and so on. This operation is called a 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 helps to mitigate the potential and 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 risks of clogging and therefore avoiding the shutdown of the unit due to clogging, controlling costs and limiting adsorbent consumption.

[0025] The said optional pretreatment step a0) may also optionally be fed by at least a fraction of a recycle stream, advantageously from step e) of the process, mixed or separately from the feed comprising a plastics pyrolysis oil.

[0026] The said optional pretreatment step a0) thus makes it possible to obtain a pretreated feed which then feeds the selective hydrogenation step a). Step a) Selective hydrogenation

[0027] According to the invention, the process comprises a step a) of selective hydrogenation of the feedstock, comprising a plastic pyrolysis oil, carried out in the presence of hydrogen, under hydrogen pressure and temperature conditions enabling the feedstock to be maintained in the liquid phase, and with just enough soluble hydrogen to selectively hydrogenate the diolefins present in the plastic pyrolysis oil. The selective hydrogenation of the diolefins in the liquid phase thus avoids, or at least limits, the formation of "gums," i.e., the polymerization of the diolefins and therefore the formation of oligomers and polymers, which can clog the reaction section of step b) of hydrotreating. This selective hydrogenation step a) yields a hydrogenated effluent, i.e., an effluent with a reduced olefin content, particularly diolefins, preferably free of diolefins.

[0028] According to the invention, said selective hydrogenation step a) is implemented in a reaction section fed at least by said feed comprising a plastics pyrolysis oil, or by the pretreated feed from the optional pretreatment step a0), and a gaseous stream comprising hydrogen (H2). Optionally, the reaction section of said step a) may also be further fed by at least a fraction of a recycle stream, advantageously from step e), either mixed with said feed, optionally pretreated, or separately from the feed, optionally pretreated, advantageously directly at the inlet of at least one of the reactors of the reaction section of step a), or according to both modes, mixed and separate from the feed, optionally pretreated.Introducing at least a fraction of said recycle stream into the reaction section of step a) of selective hydrogenation advantageously allows the impurities of the feed, possibly pre-treated, to be diluted and the temperature to be controlled, particularly in said reaction section.

[0029] The said reaction section implements selective hydrogenation, preferably in a fixed bed, in the presence of at least one selective hydrogenation catalyst, between 110 and 200°C, preferably between 130 and 180°C, a partial pressure of hydrogen between 1.0 and 10.0 MPa abs. and at a volumetric flow rate (VVH) between 1.0 and 10.0 h⁻¹. The volumetric flow rate (VVH) is defined here as the ratio between the volumetric flow rate per hour of the feed including the plastics pyrolysis oil, possibly pretreated, and the volume of catalyst(s). The quantity of gaseous flux comprising hydrogen (H2), feeding said reaction section of step a), such that the hydrogen cover is 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).Hydrogen coverage is defined as the ratio of the volumetric flow rate of hydrogen under standard temperature and pressure conditions to the volumetric flow rate of the "fresh" feed, i.e., the feed to be treated, possibly pretreated, without taking into account any recycled fraction, at 15°C (in standard conditions, m³, denoted Nm³, of H₂ per m³ of feed). The gaseous flow containing hydrogen, which feeds the reaction section of step a), may consist of added hydrogen and / or recycled hydrogen, particularly from separation step c).

[0030] Advantageously, the reaction section of said step a) comprises between 1 and 5 reactors. According to a particular embodiment of the invention, the reaction section comprises between 2 and 5 reactors, which operate in a switchable mode, known as a "Permutable Reactor System" (PRS) 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.

[0031] Advantageously, reactor internals, for example filter plates, can be used to prevent clogging of the reactor(s). An example of a filter plate is described in patent FR3051375.

[0032] Advantageously, said at least selective hydrogenation catalyst comprises a support, preferably mineral, and a hydro-dehydrogenating function.

[0033] The hydro-dehydrogenating function includes in particular at least one element from group VIII, preferably chosen from nickel and cobalt, and / or at least one element from group VIB ,preferably selected from molybdenum and tungsten. The total oxide content of the metallic elements of groups VIB and VIII (i.e., the sum of the metallic elements of groups VIB and VIII) is preferably between 1% and 40% by weight, preferably between 5% and 30% by weight relative to the total weight of the catalyst. The weight ratio, expressed as a metal oxide, of the metal(s) of group VIB to the metal(s) of group VIII is preferably between 1 and 20, and preferably between 2 and 10.For example, the reaction section of said step a) comprises a selective hydrogenation catalyst comprising between 0.5% and 10% by weight of nickel, preferably between 1% and 5% by weight of nickel (expressed as nickel oxide NiO relative to the weight of said catalyst), and between 1% and 30% by weight of molybdenum, preferably between 3% and 20% by weight of molybdenum (expressed as molybdenum oxide MoO3 relative to the weight of said catalyst) on a preferably mineral support.

[0034] The support for said at least one selective 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 at least one selective hydrogenation catalyst comprises an alumina support, preferably doped with phosphorus and optionally boron. When phosphoric anhydride (P₂O₅) is present, its concentration is less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina.When boron trioxide (B₂O₅) is present, its concentration is less than 10% by weight relative to the weight of the alumina, and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may be, for example, gamma (γ) or eth (η) alumina.

[0035] The said selective hydrogenation catalyst is, for example, in the form of extrudates.

[0036] Preferably, in order to hydrogenate the diolefins as selectively as possible, at least one selective hydrogenation catalyst used in step a) comprises less than 1% by weight of nickel and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, expressed as nickel oxide NiO relative to the weight of said catalyst, and less than 5% by weight of molybdenum and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, expressed as molybdenum oxide MoO3 relative to the weight of said catalyst, on an alumina support.

[0037] Optionally, the feed, which includes a plastic pyrolysis oil, possibly pre-treated, and / or possibly pre-mixed with at least a fraction of a recycled material stream advantageously from step e), may be mixed with the gaseous stream containing hydrogen prior to its introduction into the reaction section. This feed, possibly pre-treated, and / or possibly mixed with at least a fraction of the recycled material stream advantageously from step e), and / or possibly mixed with the gaseous stream, may also be heated before its introduction into the reaction section of step a), for example by heat exchange, particularly with the hydrotreating effluent from step b), to reach a temperature close to that used in the reaction section it feeds.

[0038] 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. The selective hydrogenation step a) converts at least 90% and preferably at least 99% of the diolefins contained in the initial feed. Step a) also removes, at least partially, other contaminants, such as silicon. The hydrogenated effluent obtained at the end of the selective hydrogenation step a) is preferably sent directly to the hydrotreatment step b). When at least a fraction of the recycled material from the optional step e) is introduced, the hydrogenated effluent obtained at the end of the selective hydrogenation step a) therefore includes, in addition to the converted feed, said fraction(s) of the recycled material. Step b) of hydrotreatment

[0039] According to the invention, the treatment process comprises a step b) of hydrotreating, in a fixed bed, said hydrogenated effluent from step a), optionally mixed with at least a fraction of a recycle stream advantageously from step e), in the presence of hydrogen and at least one hydrotreating catalyst, to obtain a hydrotreating effluent.

[0040] Advantageously, step b) implements hydrotreating reactions well known to those skilled in the art, and more particularly reactions of hydrogenation of olefins, aromatics, hydrodemetallation, hydrodesulfurization, hydrodeazotation, etc.

[0041] 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, each bed comprising at least one, and preferably no more than ten, hydrotreating catalyst(s). Where 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 arranged in series in said reactor.

[0042] Said hydrotreating reaction section is supplied at least by said hydrogenated effluent from step a) and a gaseous stream comprising hydrogen, advantageously at the level of the first catalytic bed of the first operating reactor.

[0043] The hydrotreating reaction section of step b) may also be fed by at least a fraction of the recycled stream advantageously from optional step e). Said fraction(s) of said recycled stream, or the entire recycled stream, may be introduced into said hydrotreating reaction section mixed with the hydrogenated effluent from step a), separately from said hydrogenated effluent from step a), or both mixed and separately from said hydrogenated effluent. Said fraction(s) of said recycled stream, or the entire recycled stream, may be introduced into said hydrotreating reaction section at one or more catalytic beds of said hydrotreating reaction section of step b).The introduction of at least a fraction of said recycled stream advantageously dilutes the impurities still present in the hydrogenated effluent and controls the temperature, in particular limiting the temperature rise, in the catalytic bed(s) of the hydrotreating reaction section, which employs highly exothermic reactions. Advantageously, at the end of hydrotreating step b), the entire recycled stream, advantageously from optional step e), is reintroduced into the process according to the present invention, either in a single injection or in several injections by fractions injected at the different steps a) and / or b), and / or optionally a0), of the process.

[0044] Advantageously, said hydrotreating reaction section is implemented at a pressure equivalent to that used in the reaction section of step a) of selective hydrogenation, but at a higher temperature than that of the reaction section of step a) of selective hydrogenation. Thus, said hydrotreating reaction section is implemented at a 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 (VPH) between 0.1 and 10.0 h⁻¹, preferably between 0.1 and 5.0 h⁻¹, preferably between 0.2 and 2.0 h⁻¹, preferably between 0.2 and 0.8 h⁻¹. According to the invention, the "hydrotreating temperature" corresponds to an average temperature in the hydrotreating reaction section of step b).In particular, it corresponds to the Weight Average Bed Temperature (WABT), a term well known to those skilled in the art. The hydrotreating temperature is advantageously determined based on the catalytic systems, equipment, and their configuration used. For example, the hydrotreating temperature (or WABT) is calculated as follows: WABT = (T in + 2xT out ) / 3. With T in: the temperature of the hydrogenated effluent at the inlet of the hydrotreatment reaction section, T out: the temperature of the effluent at the outlet of the hydrotreatment reaction section.

[0045] The hourly volumetric velocity (HVV) is defined here as the ratio of the hourly volumetric flow rate of the hydrogenated effluent from step a) to the volume of catalyst(s). The hydrogen coverage in step b) is between 50 and 1000 Nm³ of hydrogen per m³ of fresh feed supplying step a), and preferably between 50 and 500 Nm³ of hydrogen per m³ of fresh feed supplying step a), preferably between 100 and 300 Nm³ of hydrogen per m³ of fresh feed supplying step a). Hydrogen coverage is defined here as the ratio of the volumetric flow rate of hydrogen taken under normal temperature and pressure conditions to the volumetric flow rate of fresh feed that feeds step a), i.e., feed including a plastics pyrolysis oil, or possibly pre-treated feed, that feeds step a) (in normal m 3< , noted Nm 3< , of H 2 per m 3< of fresh feed).The hydrogen can consist of a top-up and / or recycled hydrogen, in particular from step c) of separation.

[0046] Preferably, an additional gas stream containing hydrogen is advantageously introduced at the inlet of each reactor, particularly those operating in series, and / or at the inlet of each catalytic bed from the second catalytic bed of the hydrotreating reaction section. These additional gas streams are also called cooling streams. They allow for temperature control in the hydrotreating reactor, where the reactions carried out are generally highly exothermic.

[0047] Advantageously, said at least hydrotreating catalyst used in said step b) may be selected from known hydrodemetallation, hydrotreating, silicon capture catalysts used especially for the treatment of petroleum cuts, and combinations thereof. 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.

[0048] In particular, said at least one hydrotreating catalyst comprises a support, preferably mineral, and at least one metallic element having a hydro-dehydrogenating function. Said at least one metallic element having a hydro-dehydrogenating function advantageously comprises at least one element from Group VIII, preferably selected from the group consisting of nickel and cobalt, and / or at least one element from Group VIB, preferably selected from the group consisting of molybdenum and tungsten. The total oxide content of the metallic elements from Groups VIB and VIII is preferably between 1% and 40% by weight, preferably between 5% and 30% by weight, relative to the total weight of the catalyst. The weight ratio, expressed as a metallic oxide, of the metal(s) from Group VIB to the metal(s) from Group VIII is preferably between 1.0 and 20, preferably between 2.0 and 10.For example, the hydrotreating reaction section of step b) of the process includes a hydrotreating catalyst comprising between 0.5% and 10% by weight of nickel, preferably between 1% and 5% 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 20% by weight of molybdenum, expressed as molybdenum oxide MoO3 relative to the total weight of the hydrotreating catalyst, on a mineral support.

[0049] The support for said at least one 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 at least one 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 (B₂O₅) is present, its concentration is less than 10% by weight relative to the weight of the alumina, and advantageously at least 0.001% relative to the total weight of the alumina. The alumina used may be, for example, gamma (γ) or eth (η) alumina.

[0050] The said hydrotreating catalyst is, for example, in the form of extrudates.

[0051] Advantageously, the at least one 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 ​​the hydrotreating catalyst is advantageously less than or equal to 800 m² / g, preferably less than or equal to 600 m² / g, and in particular less than or equal to 400 m² / g. The specific surface area of ​​the hydrotreating catalyst is measured by the BET method, that is, 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 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.

[0052] Hydrotreatment step b) advantageously allows for optimized treatment of the hydrogenated effluent from step a). In particular, it maximizes the hydrogenation of unsaturated bonds in olefinic compounds present in the hydrogenated effluent from step a), the hydrodemetallation of said hydrogenated effluent, and the capture of metals, especially silicon, still present in the hydrogenated effluent. Hydrotreatment step b) also enables the hydrodeazotation (HDN) of the hydrogenated effluent, that is, the conversion of nitrogen species still present in the hydrogenated effluent. Preferably, the nitrogen content of the hydrotreated effluent after step b) is less than or equal to 10 ppm by weight.

[0053] In a preferred embodiment of the invention, said hydrotreating reaction section comprises several fixed-bed reactors, preferably between two and five, most preferably between two and four, each having n catalytic beds, n being an integer greater than or equal to one, preferably between one and ten, preferably between two and five, and advantageously operating in series and / or in parallel and / or in switchable mode (or PRS) and / or in swing mode. The various possible operating modes, PRS (or lead and lag) and swing modes, are well known to those skilled in the art and are advantageously defined above. The advantage of a hydrotreating reaction section comprising several reactors lies in the optimized treatment of the hydrogenated effluent, while reducing the risk of clogging of the catalytic bed(s) and thus preventing unit shutdown due to clogging.

[0054] According to a highly preferred embodiment of the invention, said hydrotreating reaction section comprises, preferably, the following: (b1) two fixed-bed reactors operating in swing or PRS mode, preferably in PRS mode, each of the two reactors preferably having a catalytic bed advantageously comprising a hydrotreating catalyst preferably selected from known hydrodemetallation catalysts, silicon capture catalysts and combinations thereof, and (b2) at least one fixed-bed reactor, preferably one reactor, located downstream of the two reactors (b1), and advantageously operating in series with the two reactors (b1), said fixed-bed reactor (b2) having between 1 and 5 catalytic beds arranged in series and each comprising between one and ten hydrotreating catalyst(s), at least one of said hydrotreating catalysts advantageously comprising a support and at least one metallic element preferably comprising at least one element of group VIII, preferably selected from nickel and cobalt, and / or at least one element of group VIB, preferably selected from molybdenum and tungsten..

[0055] Optionally, step b) may implement a heating section located upstream of the hydrotreating reaction section, in which the hydrogenated effluent from step a) is heated to reach a temperature suitable for hydrotreating, i.e., a temperature between 250 and 430°C. This optional heating section may thus include one or more heat exchangers, preferably allowing heat exchange between the hydrogenated effluent and the hydrotreating effluent, and / or a preheating furnace.

[0056] Advantageously, step b) of hydrotreating allows for the complete hydrogenation of the olefins present in the initial feed and those potentially obtained after step a) of selective hydrogenation, but also for the conversion, at least in part, of other impurities present in the feed, such as aromatic compounds, metallic compounds, sulfur compounds, nitrogen compounds, halogenated compounds (particularly chlorinated compounds), and oxygenated compounds. Step b) can also further reduce the contaminant content, such as that of metals, especially silicon. Step c) of separation

[0057] According to the invention, the treatment process includes a separation step c), implemented in at least one washing / separation section fed at least by the hydrotreatment effluent from step b) and an aqueous solution, to obtain at least one gaseous effluent, one aqueous effluent and one hydrocarbon effluent.

[0058] The gaseous effluent obtained at the end of step c) advantageously comprises hydrogen, preferably comprising at least 90% by volume, preferably at least 95% by volume, and preferably at least 99% by volume of hydrogen. Advantageously, said gaseous effluent may at least partially be recycled to steps a) selective hydrogenation and / or b) hydrotreating, the recycling system possibly including a purification section.

[0059] The aqueous effluent obtained at the end of step c) advantageously comprises ammonium salts and / or hydrochloric acid.

[0060] The hydrocarbon effluent from step c) comprises hydrocarbon compounds and advantageously corresponds to the plastics pyrolysis oil of the feed, or to the plastics pyrolysis oil and the conventional petroleum feed fraction co-treated with the pyrolysis oil, freed at least in part of its impurities, in particular its olefinic (di- and mono-olefins), metallic, halogenated impurities.

[0061] This separation step (c) allows, in particular, the removal of ammonium chloride salts, which are formed by the reaction between chloride ions (released by the hydrogenation of chlorinated compounds in step b) and ammonium ions (generated by the hydrogenation of nitrogen compounds in step b) and / or supplied by the injection of an amine). This process limits the risk of blockage, particularly in transfer lines and / or in sections of the process of the invention and / or in transfer lines to the steam cracker, due to the precipitation of ammonium chloride salts. It also allows the removal of hydrochloric acid formed by the reaction of hydrogen and chloride ions.

[0062] Depending on the content of chlorinated compounds in the initial feed to be treated, a flow of amines can be injected upstream of the selective hydrogenation step a), between the selective hydrogenation step a and the hydrotreating step b, and / or between the hydrotreating step b and the separation step c, preferably upstream of the selective 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.

[0063] Step c) of separation includes an injection of an aqueous solution, preferably an injection of water, into the hydrotreatment effluent from step b), 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.

[0064] Step c) of separation is carried out at a temperature between 200 and 300°C. Advantageously, step c) of separation is carried out at a pressure close to that used in steps a) and / or b), preferably between 1.0 and 10.0 MPa, so as to facilitate hydrogen recycling.

[0065] The washing / separation section of step c) can at least partly be 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.).

[0066] In a possible embodiment of the invention, considered in addition to or in isolation from other embodiments of the invention described, step c) of separation comprises the injection of an aqueous solution into the hydrotreatment effluent from step b) followed by the washing / separation section advantageously comprising a separation phase enabling the production of at least one aqueous stream loaded with ammonium salts, a washed liquid hydrocarbon stream, and a partially washed gaseous stream. The aqueous stream loaded with ammonium salts and the washed liquid hydrocarbon stream can then be separated in a settling tank to obtain said hydrocarbon effluent and said aqueous effluent.The partially washed gas stream 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 hydrotreatment effluent. This allows for the removal, at least in part, and preferably in full, of the hydrochloric acid contained in the partially washed gas stream, thus yielding the gaseous effluent, preferably consisting primarily of hydrogen, and an acidic aqueous stream. The 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 the separation step (c) into the aqueous solution upstream of the scrubbing / separation section and / or into 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.

[0067] In another possible embodiment of the invention, taken separately or in combination with other embodiments of the invention described, the separation step (c) may advantageously include a "high-pressure" washing / separation section operating at a pressure close to that of the selective hydrogenation step (a) and / or the hydrotreating step (b), in order to facilitate hydrogen recycling. This possible "high-pressure" section of step (c) may be supplemented by a "low-pressure" section to obtain a hydrocarbon liquid fraction free of some of the high-pressure dissolved gases, intended for direct treatment in a steam cracking process or, optionally, for use in the fractionation step (d).

[0068] The hydrocarbon effluent from separation step c) is sent, in part or in whole, either directly to the inlet of a steam cracking unit or to an optional fractionation step d). Preferably, the liquid hydrocarbon effluent is sent, in part or in whole, preferably in whole, to a fractionation step d). Step d) (optional) of splitting

[0069] 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 gas stream and at least one hydrocarbon stream.

[0070] In a particular embodiment, the optional fractionation step (d) may provide, in addition to said at least gas stream, at least two hydrocarbon streams having different boiling points. Said fractionation step (d) may, for example, provide, in addition to a gas stream, a naphtha cut comprising compounds having a boiling point below 150°C, preferably between 80 and 150°C, and a hydrocarbon cut comprising compounds having a boiling point above 150°C, or a naphtha cut comprising compounds having a boiling point below 150°C, in particular between 80 and 150°C, a diesel cut comprising compounds having a boiling point between 150°C and 385°C, and a hydrocarbon cut comprising compounds having a boiling point above 385°C, referred to as a heavy hydrocarbon cut.

[0071] Step d) allows, in particular under the action of a flow of water vapor, in particular to eliminate gases dissolved in the liquid hydrocarbon effluent, such as ammonia, hydrogen sulfide and light hydrocarbons having 1 to 4 carbon atoms.

[0072] The optional fractionation step d) is advantageously carried out at a pressure less than or equal to 1.0 MPa abs., preferably between 0.1 and 1.0 MPa abs.

[0073] In one embodiment, step d) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit including a reflux flask. This stripping column is fed by the hydrocarbon liquid effluent from step c) and by a steam stream. 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 comprising a reflux flask in which gas / liquid separation takes place. The gaseous phase, which includes the light hydrocarbons, is withdrawn from the reflux flask as a gas stream. At least a fraction of the liquid phase is advantageously withdrawn from the reflux flask as a hydrocarbon stream with a relatively low boiling point, for example, a naphtha cut with a boiling point below 150°C.A hydrocarbon stream, advantageously liquid, with a boiling point higher than the hydrocarbon stream withdrawn from the top of the column, for example higher than 150°C, is withdrawn from the bottom of the stripping column.

[0074] According to other embodiments, step d) of fractionation may employ a stripping column followed by a distillation column or only a distillation column.

[0075] The hydrocarbon stream(s) obtained, for example the naphtha cut comprising compounds having a boiling point below 150°C and the cut comprising compounds having a boiling point above 150°C, possibly mixed, may be sent, in whole or in part, preferably in part, to a steam cracking unit, at the end of which olefins may be (re)formed to participate in the formation of polymers. Preferably, only part of the hydrocarbon stream(s) obtained is sent to a steam cracking unit; at least a fraction of the remaining part of the hydrocarbon stream(s) obtained is possibly sent to recycling step e) and / or to a fuel pool, for example naphtha pool, diesel pool or kerosene pool, from conventional petroleum feedstocks.

[0076] For example, following the optional fractionation step d) which yielded two hydrocarbon streams, the naphtha stream advantageously comprising compounds with a boiling point below 150°C can be sent in whole or in part to a naphtha pool, i.e. to the naphtha effluents from more conventional petroleum feedstocks, while the second hydrocarbon stream advantageously comprising compounds with a boiling point above 150°C is sent, in whole or in part, to a steam cracking unit. According to another example, the optional step d) leads to obtaining at least one naphtha cut (in particular comprising compounds with a boiling point below 150°C), one diesel cut (in particular comprising compounds with a boiling point between 150°C and 385°C) and one heavy cut (in particular comprising compounds with a boiling point above 385°C);The naphtha cut can be sent, in whole or in part, to the naphtha pool from conventional petroleum feedstocks; the diesel cut can also be sent, in whole or in part, either to a steam cracking unit or to a diesel pool from conventional petroleum feedstocks; the heavy cut can be sent, at least in part, to a steam cracking unit, or possibly sent at least in part to another conventional petroleum feedstock processing unit, such as a vacuum distillate processing unit like a hydrocracking unit. Step e) (optional) of recycling part of the product

[0077] The process according to the invention includes recycling step e), in which a fraction of the hydrocarbon effluent from separation step c), or a fraction of the hydrocarbon stream(s) from the optional fractionation step d), is recovered to form a recycle stream that is sent upstream of, or directly to, at least one of the reaction steps of the process according to the invention, in particular to selective hydrogenation step a) and / or hydrotreating step b). Optionally, a fraction of the recycle stream may be sent to the optional step a0. Preferably, the process according to the invention includes recycling step e).

[0078] Recycling step e) includes a recovery phase of a fraction of the hydrocarbon effluent from separation step c) or a fraction of one or more of the hydrocarbon streams from the optional fractionation step d) to constitute the recycle stream, and a recycling phase of said recycle stream at least to selective hydrogenation step a) or hydrotreating step b) or to steps a) and b). The recycle stream may feed said reaction steps a) or b) in a single injection or may be divided into several fractions to feed reaction steps a) and / or b) in several injections, i.e., at different catalytic beds. Preferably, at least a fraction of the recycle stream feeds hydrotreating step b). Optionally, a fraction of the recycle stream may feed the optional pretreatment step a0).Preferably, at the end of step b), the entire recycle stream is reintroduced into the process.

[0079] Advantageously, the quantity of the recycled stream, i.e. the recycled fraction of the product obtained, is adjusted so that the weight ratio between the recycled stream and the feed including a plastic pyrolysis oil, i.e. the feed to be treated supplying the overall process, is less than or equal to 10, preferably less than or equal to 5, and preferably greater than or equal to 0.001, preferably greater than or equal to 0.01, and most preferably greater than or equal to 0.1. Most preferably, the quantity of the recycled stream is adjusted so that the weight ratio between the recycled stream and the feed including a plastic pyrolysis oil is between 0.2 and 5.

[0080] Advantageously, for the start-up phases of the process, an external hydrocarbon fraction can be used as a recycled feedstock. Those skilled in the art will then be able to select the appropriate hydrocarbon fraction.

[0081] Recycling part of the product obtained to or upstream of at least one of the reaction steps of the process according to the invention 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.

[0082] According to a preferred embodiment of the invention, the process for treating a feed comprising a plastic pyrolysis oil preferably consists of the sequence of steps, preferably in the given order, a) selective hydrogenation, b) hydrotreatment, c) separation and d) fractionation, to produce a treated plastic pyrolysis oil of composition compatible with the input of a steam cracking unit.

[0083] According to another preferred embodiment of the invention, the process for treating a feed comprising a plastic pyrolysis oil preferably consists of the sequence of steps, and preferably in the given order, a0) pretreatment, a) selective hydrogenation, b) hydrotreatment, c) separation and d) fractionation, to produce a treated plastic pyrolysis oil of composition compatible with the inlet of a steam cracking unit.

[0084] According to a third preferred embodiment of the invention, the process for treating a feed comprising a plastic pyrolysis oil comprises, preferably, the sequence of steps, and preferably in the given order, a) selective hydrogenation, b) hydrotreating, c) separation, d) fractionation and e) recycling of a fraction of the product, to produce a treated plastic pyrolysis oil of composition compatible with the input of a steam cracking unit.

[0085] According to a fourth preferred embodiment of the invention, the process for treating a feed comprising a plastic pyrolysis oil preferably comprises the following steps, preferably in the given order: a0) pretreatment, a) selective hydrogenation, b) hydrotreatment, c) separation, d) fractionation and e) recycling of a fraction of the product, to produce a treated plastic pyrolysis oil of composition compatible with the input of a steam cracking unit.

[0086] The hydrocarbon effluent or hydrocarbon stream(s) thus obtained by treating a plastic pyrolysis oil according to the process of the invention, 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 metallic content is less than or equal to 5.0 ppm by weight, preferably less than or equal to 2.0 ppm by weight, preferably less than or equal to 1.0 ppm by weight, and preferably less than or equal to 0.5 ppm by weight, with: a silicon (Si) content less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.6 ppm by weight, and an iron (Fe) content less than or equal to 100 ppb by weight, a sulfur content less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight, a nitrogen content less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight, an asphaltene content less than or equal to 5.0 ppm by weight, a total chlorine content less than or equal to 50 ppb by weight, and an olefinic compound (mono- and di-olefin) content 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 0.5% by weight.

[0087] 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.

[0088] The process according to the invention thus makes it possible to treat plastic pyrolysis oils to obtain an effluent that can be injected, in whole or in part, into a steam cracking unit. The process according to the invention therefore makes it possible to valorize plastic pyrolysis oils, while reducing coke formation and thus the risks of clogging and / or premature loss of activity of the catalyst(s) used in the steam cracking unit, and reducing the risk of corrosion. Step f) of steam cracking (optional)

[0089] The hydrocarbon effluent from the separation step c), or the hydrocarbon stream(s) from the optional step d), may be sent in whole or in part to a steam cracking step f).

[0090] The steam cracking step (f) 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 relative pressure between 0.05 and 0.3 MPa. 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 (f) and after separation (or fractionation). The quantity of water introduced, advantageously in the form of steam, is between 0.3 and 3.0 kg of water per kg of hydrocarbon compounds entering step (f). Preferably, the optional step f) is carried out in several pyrolysis ovens in parallel in order to adapt the operating conditions to the different flows feeding step f) in particular from step d), and also to manage the decoding 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, one furnace might be dedicated to cracking a hydrocarbon stream containing compounds with a boiling point below 150°C, particularly between 80 and 150°C, and another furnace might be dedicated to the hydrocarbon stream containing compounds with a boiling point above 150°C.

[0091] This steam cracking step (f) 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% by weight, especially greater than or equal to 40% by weight, or even greater than or equal to 50% by weight of total olefins comprising 2, 3, and 4 carbon atoms relative to the weight of the steam cracking effluent. These C2, C3, and C4 olefins can then be advantageously used as polyolefin monomers.

[0092] According to one or more preferred embodiment(s) of the invention, taken separately or combined together, the process for treating a feed comprising a plastic pyrolysis oil comprises, preferably, the sequence of steps described above, and preferably in the order given, that is to say: step a0) of pretreatment, step a) of selective hydrogenation, step b) of hydrotreatment, step c) of separation, optionally step d) of fractionation, and step f) of steam cracking.

[0093] The process according to the invention, when it includes this step f) of steam cracking, thus makes it possible to obtain from pyrolysis oils of plastics, for example of plastic waste, olefins which can be used as monomers for the synthesis of new polymers contained in plastics, at relatively satisfactory yields, without clogging or corrosion of the units.

[0094] The following figures and examples illustrate the invention without limiting its scope. Analytical methods used

[0095] The analytical methods and / or standards used to determine the characteristics of the various flows, particularly the load to be treated and the effluents, are known to those skilled in the art. They are listed below: Table 1 Features Methods Density @15°C ASTM D4052 Sulfur content ISO 20846 Nitrogen content ASTM D4629 Hint acid ASTM D664 Bromine content ASTM D1159 Content of Di-Olefins based on the Maleic Anhydride Index Method MAV as described in the article : C. López-García et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol.62 (2007), No.1, 57-68 Oxygen content Combustion + Infrared Paraffin Content UOP990-11 Content of Naphthenes UOP990-11 Olefin content UOP990-11 Aromatic Content UOP990-11 Content of Halogens ASTM-D7359 Content of Asphaltenes IFP9313 Chloride content ASTM D7536 Metal content: ASTM-D5185 P Fe If N / A B Simulated Distillation ASTM D2887 LIST OF FIGURES

[0096] The mention of the elements referenced in the Figures 1 to 3 allows for a better understanding of the invention, without limiting it to the particular embodiments illustrated in the Figures 1 to 3The different embodiments presented can be used alone or in combination with each other, without limitation of combination.

[0097] There Figure 1 represents the diagram of a particular embodiment of the process of the present invention, comprising: a step a) of selective hydrogenation of a hydrocarbon feedstock from the pyrolysis of plastics 1, in the presence of a hydrogen-rich gas 2, a fraction R1 of a recycle stream R and possibly an amine supplied by the stream 3, carried out in at least one fixed-bed reactor comprising at least one selective hydrogenation catalyst, to obtain an effluent 4; a step b) of hydrotreating the effluent 4 from step a), in the presence of hydrogen 5 and two fractions R2 and R3 of a recycle stream R, carried out in at least one fixed-bed reactor comprising at least one hydrotreating catalyst, to obtain a hydrotreated effluent 6; a step c) of separating the effluent 6 carried out in the presence of an aqueous washing solution 7 and allowing to obtain at least one fraction 8 comprising hydrogen, an aqueous fraction 9 containing dissolved salts, and a hydrocarbon liquid fraction 10;the recycling of a part R of the hydrocarbon fraction 10 from step c), said part R constituting the recycle stream and being divided into 3 fractions R1, R2, R3, to feed the step a) of selective hydrogenation (fraction R1), and the step b) of hydrotreating (fractions R2 and R3). ;

[0098] Instead of injecting the amine 3 flux into the inlet of step a) selective hydrogenation, it is possible to inject it into the inlet of step b) hydrotreating, into the inlet of step c) separation or not to inject it at all, depending on the characteristics of the feed.

[0099] There Figure 2 represents another particular embodiment of the process according to the invention. In the embodiment shown in the Figure 2, the hydrocarbon liquid fraction 10, obtained at the end of step c) is sent to a fractionation step d) allowing to obtain at least a gaseous fraction 11, a fraction including naphtha 12 and a hydrocarbon fraction 13. A part R of the hydrocarbon fraction 13 from step d) constitutes the recycle stream which feeds the hydrotreating step b).

[0100] There Figure 3 represents a variant of the implementation of the process according to the invention shown in the Figure 1 In the embodiment shown on the Figure 3The hydrocarbon feedstock from the pyrolysis of plastics 1 undergoes a pretreatment step a0) prior to the selective hydrogenation step a). The pretreated feedstock 14 then feeds the selective hydrogenation step a). Furthermore, the liquid hydrocarbon fraction 10 obtained at the end of step c) is sent to a fractionation step d) to obtain at least a gaseous fraction 11, a fraction including naphtha 12, and a hydrocarbon fraction 13. A recycled stream R, consisting of a portion of the hydrocarbon fraction 13, is divided into three fractions R1, R2, and R3 to feed the selective hydrogenation step a (fraction R1) and the hydrotreating step b (fractions R2 and R3).

[0101] Only the main stages, with the main flows, are represented on the Figures 1 to 3To facilitate a better understanding of the invention, it is understood that all 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 recycled), 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.

[0102] At the end of step d), the fraction comprising naphtha 12 and / or the hydrocarbon fraction 13 is / are sent to a steam cracking process. EXAMPLES Example 1 (according to the invention)

[0103] The feed 1 treated in the process is a plastics pyrolysis oil (i.e. comprising 100% by weight of said plastics pyrolysis oil) having the characteristics indicated in Table 2. Table 2: Load characteristics Description / Methods Unit Pyrolysis oil Density @15°C ASTM D4052 g / cm³< 0,820 Sulfur content ISO 20846 ppm weight 25000 Nitrogen content ASTM D4629 ppm weight 730 Acid value ASTM D664 mgKOH / g 1,5 Bromine content ASTM D1159 g / 100g 80 Content of Di-Olefins based on the Maleic Anhydride Index MAV Method (1)< % weight 10 Oxygen content Combustion - Infrared % weight 1,0 Paraffin Content UOP990-11 % weight 45 Content of Naphthenes UOP990-11 % weight 20 Olefin content UOP990-11 % weight 25 Aromatic Content UOP990-11 % weight 10 Content of Halogens ASTM-D7359 ppm weight 350 Content of Asphaltenes IFP9313 ppm weight 380 Chloride content ASTM D7536 ppm weight 320 Metal content: ASTM-D5185 P ppm weight 10 Fe ppm weight 25 If ppm weight 45 N / A ppm weight 2 B ppm weight 2 Simulated Distillation: ASTM D2887 0% °C 40 10% °C 98 30% °C 161 50% °C 232 70% °C 309 90% °C 394 100% °C 432 (1) MAV method described in the article: C. López-García et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68

[0104] The charge 1 is subjected to a step a) of selective hydrogenation carried out in a fixed bed reactor and in the presence of hydrogen 2 and a NiMo on Alumina type selective hydrogenation catalyst under the conditions indicated in Table 3. Table 3: Conditions for step a) of selective hydrogenation Temperature °C 150 Partial Pressure of Hydrogen MPa abs 6,4 H2 / HC (Volume coverage of hydrogen relative to the volume of charge) Nm 3< / m 3< 10 VVH (volumetric charge flow rate / volume of catalysts) h -1< 6

[0105] At the end of step a) of selective hydrogenation, all of the diolefins initially present in the feed have been converted.

[0106] The effluent 4 from step a) of selective hydrogenation is directly subjected, without separation, to a step b) of hydrotreating carried out in a fixed bed and in the presence of hydrogen 5, a hydrocarbon stream of recycle R, and a NiMo on Alumina type hydrotreating catalyst under the conditions presented in Table 4. Table 4: Conditions for step b) of hydrotreatment Hydrotreatment temperature °C 355 Partial Pressure of Hydrogen MPa abs 6,2 H2 / HC (Volume coverage of hydrogen relative to the volume of charge) Nm 3< / m 3< 300 VVH (volumetric charge flow rate / volume of catalysts) h -1< 0,5

[0107] The effluent 6 from hydrotreatment step b) is subjected to a separation step c) in which a stream of water is injected into the effluent from hydrotreatment step b); the mixture is then treated in an acid gas scrubbing column and separator drums. The resulting liquid effluent is then sent to a fractionation step d) which includes a stripping column. The yields of the different fractions obtained after separation and fractionation are shown in Table 5 (the yields being the ratios of the mass quantities of the different products obtained to the mass of feedstock upstream of step a), expressed as a percentage and denoted % w / w). Table 5: Yields of the different products obtained after separation and fractionation NH3 + H2S % m / m 0,35 C1-C4 Fraction % m / m 0,50 PI-150°C Fraction % m / m 28,10 Fraction 150°C+ % m / m 71,40 Fraction PI+ (mixture of fractions PI-150°C and 150°C+) % m / m 99,50

[0108] Part of the 150°C+ fraction is recycled to hydrotreating step b) as a recycled stream. The quantity of 150°C+ fraction is adjusted so that the weight ratio between the recycled fraction and the fresh feed 1 is 1.

[0109] It appears that the temperature difference between the inlet and outlet of the hydrotreating reaction section, with the hydrotreating temperature (or mean hydrotreating temperature, WABT) adjusted to 355°C, is reduced compared to a process according to the invention but not involving the recycling of a fraction of the hydrocarbon effluent obtained. This means that recycling a fraction of the hydrocarbon effluent obtained makes it possible to control the temperature in the hydrotreating reaction section where the reactions involved are highly exothermic.

[0110] The characteristics of the liquid fractions PI-150°C and 150°C+ (as well as the fraction Pl+ which is the sum of the fractions PI-150°C and 150°C+) obtained after step c) of separation and a fractionation step are presented in Table 6: Table 6: Characteristics of the fractions PI-150°C, 150°C+ and Pl+ Analysis (method) PI-150°C Fraction Fraction 150°C+ PI+ fraction Density @ 15°C (ASTM D4052) g / cm³< 0,750 0,827 0,804 Content of: Sulfur (ASTM D5453) ppm weight < 2 < 10 < 10 Nitrogen (ASTM D4629) ppm weight < 0,5 < 5 < 5 Fe (ASTM D5185) ppb weight Not detected < 50 < 50 Total Metals (ASTM D5185) ppm weight Not detected < 1 < 1 Chlorine (ASTM D7536) ppb weight Not detected < 25 < 25 Paraffins (UOP990-11) % weight 68 65 66 Naphthenes (UOP990-11) % weight 30,5 33 32 Olefins (UOP990-11) % weight not detected not detected not detected Aromatics (UOP990-11) % weight 1,5 2 2 Simulated Distillation (ASTM D2887) 0% °C 25 150 25 5% °C 32 162 53 10% °C 40 174 92 30% °C 82 226 155 50% °C 108 281 227 70% °C 126 346 305 90% °C 142 395 391 95% °C 146 404 398 100% °C 150 432 432

[0111] Both the PI-150°C and 150°C+ liquid fractions have compositions compatible with a steam cracking unit because: They do not contain olefins (mono- and di-olefins); they have very low chlorine content (respectively an undetected content and a content of 25 ppb wt) and are below the limit required for a steam cracker feed (≤ 50 ppb wt); the metal content, in particular iron (Fe), is also very low (undetected metal content for the PI-150°C fraction and < 1 ppm wt for the 150°C+ fraction; undetected Fe content for the PI-150°C fraction and 50 ppb wt for the 150°C+ fraction) and is below the limits required for a steam cracker feed (≤ 5.0 ppm wt, preferably ≤ 1 ppm wt for metals; ≤ 100 ppb wt for Fe);Finally, they contain sulfur (< 2 ppm by weight for the PI-150°C fraction and < 10 ppm by weight for the 150°C+ fraction) and nitrogen (< 0.5 ppm by weight for the PI-150°C fraction and < 5 ppm by weight for the 150°C+ fraction) at levels far below the limits required for a steam cracker feed (≤ 500 ppm by weight, preferably ≤ 200 ppm by weight for S and N).

[0112] It also appears that the mixture of the two liquid fractions, named Pl+, also has very low levels of olefins and contaminants (in particular metals, chlorine, sulfur, nitrogen) making the composition compatible with a steam cracking unit.

[0113] The resulting PI-150°C and 150°C+ liquid fractions are then sent to a steam cracking stage where the liquid fractions are cracked under different conditions (see Table 7). The PI+ mixture can also be sent directly to a steam cracking stage according to the conditions mentioned in Table 7. Table 7: Steam cracking stage conditions Oven outlet pressure MPa abs 0,2 Flue outlet temperature (fractions PI-150°C) °C 800 Oven exit temperature fraction 150°C+ °C 790 Flue outlet temperature (PI+ fractions) °C 795 Vapor / fraction ratio PI-150°C+ kg / kg 0,6 Vapor / fraction ratio 150°C+ kg / kg 0,8 Vapor Ratio / PI+ Fractions kg / kg 0,7 Residence time in a PI-150°C fraction oven s 0,3 Residence time in oven fractions at 150°C+ s 0,3 Residence time four fractions PI+ s 0,3

[0114] The effluents from the different steam cracking furnaces are subjected to a separation step allowing the saturated compounds to be recycled back to the steam cracking furnaces and the yields to be obtained shown in Table 8 (yield = % mass of product relative to the mass of each of the fractions upstream of the steam cracking step, noted % w / w). Table 8: Steam cracking stage yields Fractions PI-150°C Fraction Fraction 150°C+ PI+ fraction H2, CO, C1 % m / m 7,8 7,9 8,1 Ethylene % m / m 33,7 34,2 34,8 Propylene % m / m 18,3 18,6 19,0 C4 Cup % m / m 14,6 14,8 15,1 Pyrolysis fuel % m / m 19,8 19,4 18,8 Pyrolysis oil % m / m 5,7 5,1 4,2

[0115] Considering the yields obtained for the different liquid fractions PI-150°C and 150°C+ (and their mixture PI+) during the pyrolysis oil treatment process (see Table 5), it is possible to determine the overall yields of the products from the steam cracking step relative to the initial feed of plastic pyrolysis oil introduced in step a): Table 9: Overall process yields followed by the steam cracking step Fractions PI-150°C Fraction Fraction 150°C+ PI+ fraction H2, CO, C1 % m / m 2,2 5,6 8,0 Ethylene % m / m 9,5 24,4 34,7 Propylene % m / m 5,2 13,3 18,9 C4 Cup % m / m 4,1 10,6 15,1 Pyrolysis fuel % m / m 5,6 13,9 18,7 Pyrolysis oil % m / m 1,6 3,6 4,2

[0116] When the liquid fraction PI+ is subjected to a steam cracking step, the process according to the invention achieves overall mass yields of ethylene and propylene of 34.7% and 18.9%, respectively, relative to the initial mass quantity of plastic pyrolysis oil feedstock. When the PI-150°C and 150°C+ fractions are sent to the steam cracking unit separately, the process according to the invention achieves overall mass yields of ethylene and propylene of 33.9% (= 9.5 + 24.4) and 18.5% (= 5.2 + 13.3), respectively, relative to the initial mass quantity of plastic pyrolysis oil feedstock.

[0117] Furthermore, the specific sequence of steps upstream of the steam cracking stage helps to limit the formation of coke and to avoid the corrosion problems that would have appeared if the chlorine had not been removed. Example 2 (according to the invention)

[0118] In this example, the fractionation step includes, in addition to a stripping column, a distillation section in order to obtain a diesel cut that can be directly integrated into a diesel pool, i.e. meeting the specifications required for a diesel and in particular the specification of T90 D86 at 360°C.

[0119] The load to be processed is identical to that described in Example 1 (see table 2).

[0120] It undergoes the steps a) selective hydrogenation, b) hydrotreating, and c) separation, carried out under the same conditions as those described in Example 1. The liquid effluent obtained at the end of step c) separation is sent to a stripping column, as in Example 1. At the end of the stripping column, the two fractions PI-150°C and 150°C+ are obtained, as in Example 1. They have the same characteristics as those of Example 1 (see Table 6). The 150°C+ fraction is sent to a distillation column where it is distilled into two cuts: a 150-385°C cut and a 385°C+ cut. A portion of the 385°C+ cut is recovered to form a recycling stream R, which is sent to step b) hydrotreating.

[0121] Similar to the process described in Example 1, the temperature difference between the inlet and outlet of the hydrotreating reaction section is limited compared to a process without recycle.

[0122] Table 10 gives the overall yields of the different fractions obtained at the end of steps c) of separation and d) of fractionation (which includes a stripping column and a distillation column). Table 10: Yields of the different products obtained after separation and fractionation NH3 + H2S % m / m 0,350 Fraction C 1-C4 % m / m 0,50 PI-150°C Fraction % m / m 28,10 Fraction 150_385°C+ % m / m 60,90 Fraction 385°C+ % m / m 14,63

[0123] Table 11 gives the characteristics of the 150-385°C and 385°C+ cuts, and the EN-590 commercial specifications of a diesel. Table 11: Characteristics of 150-385°C and 385°C+ cuts and EN-590 commercial specifications Features Units Cup 150-385°C 385°C+ Cup EN-590 specifications Density @ 15°C g / cm³< 0,824 0,844 0,820 - 0,845 Content of: Sulfur ppm weight < 10 < 10 < 10 Nitrogen ppm weight < 5 < 5 Cetane Number D613 55,4 - > 51 Cetane D4737A ice cream 54,4 - > 46 Aromatics % weight 2 2 < 11 Simulated Distillation D2887 0 °C 152 377 5 °C 160 381 10 °C 171 383 30 °C 216 391 50 °C 263 398 70 °C 318 404 90 °C 369 420 95 °C 380 426 100 °C 390 429 Distillation D86 0 ° C 181 402 5 ° C 187 403 10 ° C 193 396 30 ° C 225 389 50 ° C 262 384 70 ° C 305 387 90 ° C 344 394 95 ° C 355 398 < 360°C 100 ° C 358 395

[0124] Table 11 shows that the 150-385°C cut has the qualities required to be sent directly to the diesel pool. Example 3 (not in accordance with the invention)

[0125] In this example, the hydrocarbon feed of pyrolysis oil type identical to that used in example 1 is sent directly to a steam cracking step.

[0126] The mass yields of the different products obtained are calculated with respect to the initial load (see Table 12) Table 12: Steam cracking stage yields H2, CO, C1 % m / m 7,7 Ethylene % m / m 33,1 Propylene % m / m 18,0 C4 Cup % m / m 14,4 Pyrolysis fuel % m / m 20,3 Pyrolysis oil % m / m 6,5

[0127] The yields of ethylene and propylene obtained after direct steam cracking of pyrolysis oil (a process not according to the invention) and shown in Table 12 are lower than those obtained after steam cracking of a feedstock resulting from the treatment of the same pyrolysis oil from plastics of Example 1 according to the process of the invention (see Table 8), which demonstrates the advantage of the process according to the invention. Furthermore, the treatment of pyrolysis oil directly in a steam cracking furnace (Example 2) resulted in increased coke formation, necessitating premature furnace shutdown.

Claims

1. Process for the treatment of a feedstock comprising a plastics pyrolysis oil, comprising: a) a stage of selective hydrogenation carried out in a reaction section fed at least with said feedstock maintained in the liquid phase and a gas stream comprising hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature between 110 and 200°C, a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and an hourly space velocity between 1.0 and 10.0 h-1, the amount of hydrogen of the gas stream employed in stage a) being of between 1 and 50 Nm3 of hydrogen per m3 of feedstock, to obtain a hydrogenated effluent; b) a hydrotreating stage carried out in a hydrotreating reaction section, employing a fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreating catalyst, said hydrotreating reaction section being fed at least with said hydrogenated effluent resulting from stage a) and a gas stream comprising hydrogen, said hydrogenated effluent resulting from stage a) and said gas stream comprising hydrogen being introduced into the hydrotreating reaction section at the level of the first catalytic bed of said section, said hydrotreating reaction section being used at a temperature between 250 and 430°C, a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h-1, the amount of hydrogen of the gas stream employed in stage b) being of between 50 and 1000 Nm3 of hydrogen per m3 of fresh feedstock which feeds stage a), to obtain a hydrotreating effluent; c) a separation stage, fed with the hydrotreating effluent resulting from stage b) and an aqueous solution, said stage being operated at a temperature between 200 and 300°C, said separation stage c) comprising an injection of an aqueous solution into the hydrotreating effluent resulting from stage b), upstream of the washing / separation section, to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent; d) optionally a stage of fractionating all or part of the hydrocarbon effluent resulting from stage c), to obtain at least one gas stream and at least one hydrocarbon stream; e) a recycling stage comprising a phase of recovery of a fraction of the hydrocarbon effluent resulting from the separation stage c) or a fraction of the or of at least one of the hydrocarbon stream(s) resulting from the optional fractionation stage d), to constitute a recycle stream, and a phase of recycling said recycle stream to at least the selective hydrogenation stage a), the hydrotreating stage b) or stages a) and b).

2. Process according to Claim 1, in which the hydrotreating reaction section of stage b) is additionally fed with at least one fraction of the recycle stream resulting from stage e) which is (are) introduced into said hydrotreating reaction section as a mixture with the hydrogenated effluent resulting from stage a), separately from said hydrogenated effluent resulting from stage a) or according to the two modes as a mixture and separately from said hydrogenated effluent.

3. Process according to Claim 1 or 2, in which the reaction section of stage a) is additionally fed with at least one fraction of the recycle stream resulting from stage e), either as a mixture with said feedstock or separately from the feedstock, or also according to the two modes as a mixture and separately from the feedstock.

4. Process according to one of the preceding claims, comprising said fractionation stage d).

5. Process according to one of the preceding claims, comprising a stage a0) of pretreatment of the feedstock comprising a plastics pyrolysis oil, said pretreatment stage being carried out prior to the selective hydrogenation stage a) in an adsorption section, operated in the presence of at least one adsorbent, and / or in a solid / liquid separation section, said pretreatment stage being fed with said feedstock and operating at a temperature between 0 and 150°C, preferably between 5 and 100°C, and at a pressure between 0.15 and 10.0 MPa abs., preferably between 0.2 and 1.0 MPa abs., to obtain a pretreated feedstock which feeds stage a).

6. Process according to one of the preceding claims, in which the selective hydrogenation stage a) is carried out at a temperature between 130 and 180°C.

7. Process according to one of the preceding claims, in which the amount of hydrogen of the gas stream employed in stage a) is of between 5 and 20 Nm3 of hydrogen per m3 of feedstock.

8. Process according to one of the preceding claims, in which the reaction section of stage a) employs at least two reactors preferably operating in permutable mode.

9. Process according to one of the preceding claims, in which said at least selective hydrogenation catalyst comprises a support, preferably chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and their mixtures, and a hydrodehydrogenating function comprising at least one element from group VIII, preferably chosen from the group consisting of nickel and cobalt, and / or at least one element from group VIB, preferably chosen from the group consisting of molybdenum and tungsten.

10. Process according to Claim 9, in which said at least selective hydrogenation catalyst comprises less than 1% by weight of nickel, expressed as nickel oxide NiO with respect to the weight of said catalyst, and less than 5% by weight of molybdenum, expressed as molybdenum oxide MoO3 with respect to the weight of said catalyst, on an alumina support.

11. Process according to one of the preceding claims, in which n is between 2 and 10, and an additional gas stream comprising hydrogen is introduced into the inlet of each catalytic bed starting from the second catalytic bed of the hydrotreating reaction section of stage b).

12. Process according to one of the preceding claims, in which the amount of hydrogen of the gas stream employed in stage b) between 100 and 300 Nm3 of hydrogen per m3 of fresh feedstock which feeds stage a).

13. Process according to one of the preceding claims, in which said at least one hydrotreating catalyst comprises a support, preferably chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and their mixtures, and a hydrodehydrogenating function comprising at least one element from group VIII, preferably chosen from the group consisting of nickel and cobalt, and / or at least one element from group VIB, preferably chosen from the group consisting of molybdenum and tungsten.

14. Process according to one of the preceding claims, in which said at least one hydrotreating catalyst exhibits a specific surface of greater than or equal to 250 m2 / g, preferably of greater than or equal to 300 m2 / g.

15. Process according to one of the preceding claims, additionally comprising a steam cracking stage f), carried out in at least one pyrolysis furnace at a temperature of between 700 and 900°C and at a pressure of between 0.05 and 0.3 MPa relative.