CN116194555A

CN116194555A - Method for treating plastic pyrolysis oil comprising two-step hydrocracking

Info

Publication number: CN116194555A
Application number: CN202180059087.8A
Authority: CN
Inventors: W·维斯; J·博纳尔多特; I·里巴斯桑圭萨
Original assignee: Repsol SA; IFP Energies Nouvelles IFPEN
Current assignee: Repsol SA; IFP Energies Nouvelles IFPEN
Priority date: 2020-07-30
Filing date: 2021-07-26
Publication date: 2023-05-30
Also published as: US20230287283A1; EP4189038A1; BR112023001482A2; KR20230044444A; CA3185358A1; AU2021318798A1; FR3113060B1; TW202216968A; FR3113060A1; JP2023535638A; WO2022023263A1

Abstract

The invention relates to a method for treating plastic pyrolysis oil, comprising: a) Selective hydrogenation of the feedstock to obtain a hydrogenation effluent; b) Hydrotreating of the hydrotreated effluent to obtain a hydrotreated effluent; c) A first hydrocracking step of the hydrotreated effluent to obtain a first hydrocracked effluent; d) Separation of the hydrocracking effluent in the presence of an aqueous stream to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent; e) Fractionating the hydrocarbon-based liquid effluent to obtain at least one gas stream and at least one naphtha fraction and a heavier fraction; f) A second hydrocracking step of the heavier fraction to obtain a second hydrocracking effluent; g) Recycling at least a portion of the second hydrocracking effluent to separation step d).

Description

Method for treating plastic pyrolysis oil comprising two-step hydrocracking

Technical Field

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

Thus, the process of the present invention allows for the treatment of plastic pyrolysis oil to obtain an effluent that may be fully or partially injected into a steam cracking unit. Thus, the process of the present invention makes it possible to upgrade plastic pyrolysis oil while reducing coke formation and thus the risk of premature loss of activity of one or more catalysts used in the plugging and/or steam cracking unit and reducing the risk of corrosion.

Prior Art

Plastics obtained from collection and sorting channels may undergo a pyrolysis step to obtain pyrolysis oil, among other things. These plastic pyrolysis oils are typically burned to produce electricity and/or used as fuel in industrial boilers or municipal heating.

Another approach to upgrading plastic pyrolysis oils is to use these plastic pyrolysis oils as feedstock for a steam cracking unit to (re) produce olefins, which are constituent monomers of certain polymers. However, plastic waste is typically a mixture of several polymers, such as a mixture of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride and polystyrene. Furthermore, depending on the application, the plastics may contain other compounds besides the polymers, such as plasticizers, pigments, colorants or polymerization catalyst residues. Plastic waste may also contain small amounts of biomass, for example from household waste. As a result, the oils obtained from the pyrolysis of plastic waste contain many impurities, in particular diolefins, metals, in particular silicon, or halogenated compounds, in particular chlorine-based compounds, miscellaneous elements such as sulphur, oxygen and nitrogen, and insoluble substances, in contents which are generally high and incompatible with the steam cracking unit or units located downstream of the steam cracking unit, in particular the polymerization process and the selective hydrogenation process. These impurities may cause handling problems, in particular problems of corrosion, coking or catalytic deactivation, or incompatibility problems in the applications of the target polymers. The presence of diolefins can also lead to problems with instability of pyrolysis oils, characterized by gum formation. Gum and insoluble materials that may be present in pyrolysis oil can cause plugging problems in the process.

Furthermore, during the steam cracking step, the yields of the light olefins, particularly ethylene and propylene, sought by petrochemistry are greatly dependent on the quality of the feedstock sent to steam cracking. BMCI (mineral office related index) is commonly used to characterize hydrocarbon fractions. Overall, as the paraffin content increases and/or as BMCI decreases, the yield of light olefins increases. Conversely, as BMCI increases, the yield of undesirable heavy compounds and/or coke increases.

WO 2018/055555 proposes an overall process for recycling plastic waste, which is very common and relatively complex, from various steps of pyrolysis of plastic waste to steam cracking steps. The process of patent application WO 2018/055555 comprises, inter alia, a step of hydrotreating the liquid phase obtained directly from pyrolysis, preferably under very severe conditions, in particular in terms of temperature, for example at 260-300 ℃, a step of separating the hydrotreated effluent, and then a step of hydrodealkylating the separated heavy effluent, preferably at high temperature, for example at 260-400 ℃.

The unpublished patent application FR 20/01758 describes a method of treating plastic pyrolysis oil comprising:

a) Selectively hydrogenating the feedstock in the presence of hydrogen and a selective hydrogenation catalyst to obtain a hydrogenation effluent;

b) Hydrotreating the hydrotreated effluent in the presence of hydrogen and a hydrotreating catalyst to obtain a hydrotreated effluent;

c) Separating the hydrotreated effluent in the presence of an aqueous stream at a temperature of 50-370 ℃ to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent;

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

e) A recycling step comprising recycling a portion of the hydrocarbon-based effluent obtained from the separation step c) or a portion of the hydrocarbon-based stream obtained from the fractionation step d) and/or at least one to the stages in the selective hydrogenation step a) and/or the hydrotreating step b).

According to patent application FR 20/01758, the naphtha fraction obtained from the fractionation step may be fed in whole or in part to a steam cracking unit or to a naphtha pool obtained from a conventional petroleum feedstock, or may be recycled to step e).

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

While heavier fractions may be sent to the steam cracking unit, few refineries support this option. The reason for this is that the heavier fraction has a high BMCI and contains more naphthenes, naphthenes-aromatics and aromatics relative to the naphtha fraction, thus resulting in a higher C/H ratio. This high ratio is responsible for coking in the steam cracker, and thus a steam cracker dedicated to this fraction is required.

In addition, steam cracking of such heavy fractions produces smaller amounts of the products of interest, particularly ethylene and propylene, but more pyrolysis gasoline.

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

Disclosure of Invention

The present invention relates to a method of treating a feedstock comprising plastic pyrolysis oil, comprising:

a) A selective hydrogenation step in the presence of at least one selective hydrogenation catalyst at a temperature of 100 to 280 ℃ and under a partial pressure of hydrogen of 1.0 to 10.0MPa absolute and for 0.3 to 10.0h in a reaction zone fed with at least the feedstock and a gaseous stream comprising hydrogen ^-1 Is carried out at a hourly space velocity to obtain a hydrogenation effluent;

b) A hydrotreating step carried out in a hydrotreating reaction zone fed with at least the hydrogenation effluent obtained from step a) and hydrogen containing gas using at least one fixed bed reactor comprising n catalytic beds, n being an integer greater than or equal to 1, each catalytic bed containing at least one hydrotreating catalystThe hydrotreating reaction section is operated at a temperature of 250-430 ℃ and a hydrogen partial pressure of 1.0-10.0MPa absolute and for 0.1-10.0h ^-1 Is used at a hourly space velocity to obtain a hydrotreated effluent;

c) A first hydrocracking step carried out in a hydrocracking reaction zone fed with at least the hydrotreated effluent obtained from step b) and a gaseous stream comprising hydrogen, using at least one fixed bed reactor comprising n catalytic beds, n being an integer greater than or equal to 1, each catalytic bed comprising at least one hydrocracking catalyst, said hydrocracking reaction zone being at a temperature ranging from 250 to 480 ℃, a hydrogen partial pressure ranging from 1.5 to 25.0MPa absolute and a hydrogen partial pressure ranging from 0.1 to 10.0h ^-1 Is used at a hourly space velocity to obtain a first hydrocracking effluent;

d) A separation step fed with the hydrocracking effluent and the aqueous solution obtained from step c), said step being carried out at a temperature ranging from 50 to 370 ℃ to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent;

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

f) A second hydrocracking step carried out in a hydrocracking reaction zone, which is fed with at least a portion of the hydrocarbon fraction comprising compounds having a boiling point of more than 175 ℃ and a gaseous stream comprising hydrogen obtained from step e), using at least one fixed bed reactor comprising n catalytic beds, n being an integer greater than or equal to 1, each catalytic bed comprising at least one hydrocracking catalyst, said hydrocracking reaction zone being at a temperature of 250-480 ℃ at a hydrogen partial pressure of 1.5-25.0MPa absolute and a hydrogen partial pressure of 0.1-10.0h ^-1 Is operated at a hourly space velocity to obtain a second hydrocracking effluent;

g) Recycling at least a portion of said second hydrocracking effluent obtained from step f) to the step of separating step d).

An advantage of the process according to the invention is that at least a part of the impurities of the oil obtained from the pyrolysis of plastic waste are purified, which makes it possible to hydrogenate the oil and thus to upgrade it, in particular by directly incorporating it into a fuel tank, or by making it compatible with the treatment in a steam cracking unit, so as to be able to obtain light olefins, which can be used as monomers in polymer manufacture, in particular in improved yields.

Another advantage of the present invention is to prevent the risk of clogging and/or corrosion of the processing unit in which the process of the present invention is carried out, which is exacerbated by the typically high presence of diolefins, metals and halogenated compounds in plastic pyrolysis oil.

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

The invention relates to the recovery of plastics and proposes a method for treating the oil obtained from the pyrolysis of plastics to purify it, hydrotreat it and hydrocrack it, in order to obtain a hydrocarbon-based effluent with reduced impurity content, which is therefore modifiable directly in the form of a naphtha fraction and/or a diesel fraction, or which has a composition compatible with the feedstock of a steam cracking unit. Hydrocracking makes it possible to convert at least a part of the heavy fraction (diesel) into compounds of the naphtha fraction, which makes it possible to obtain an improved naphtha fraction yield and an improved light olefin yield when this fraction is sent to steam cracking, while in particular reducing the risk of plugging during plastic pyrolysis oil treatment steps such as those described in the prior art, and the risk of substantial coke formation and/or corrosion encountered during subsequent step(s), such as during the steam cracking step of plastic pyrolysis oil.

According to a variant, the process further comprises a recycling step h), wherein a portion of the hydrocarbon-based effluent obtained from the separation step d) or a portion of the naphtha fraction having a boiling point of less than or equal to 175 ℃ obtained from the fractionation step e) is sent to the selective hydrogenation step a) and/or the hydrotreating step b).

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

According to a variant, the method comprises a step a 0) of pre-treating a feedstock comprising a plastic pyrolysis oil, said pre-treatment step being carried out upstream of the selective hydrogenation step a) and comprising a filtration step and/or a step of washing with water and/or an adsorption step.

According to a variant, the reaction section of step a) or b) uses at least two reactors operating in a replaceable mode.

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

According to one variant, the selective hydrogenation catalyst comprises a support selected from alumina, silica-alumina, magnesia, clay and mixtures thereof, and comprises at least one group VIII element and at least one group VIB element, or at least one hydro-dehydrogenation function (function) of a group VIII element.

According to one variant, the at least one hydrotreating catalyst comprises a support selected from alumina, silica-alumina, magnesia, clay and mixtures thereof, and a hydro-dehydrogenation function comprising at least one group VIII element and/or at least one group VIB element.

According to a variant, the hydrocracking catalyst comprises a support selected from the group consisting of halogenated alumina, a combination of boron and aluminium oxides, amorphous silica-alumina and zeolite, and a hydro-dehydrogenation function comprising at least one group VIB metal selected from chromium, molybdenum and tungsten (alone or as a mixture) and/or at least one group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

According to this variant, the zeolite is selected from the group consisting of Y zeolite, alone or in combination with other zeolites selected from the group consisting of beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 and ZBM-30 zeolite (alone or as a mixture).

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

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

According to this variant, at least a portion of the light naphtha fraction is sent to steam cracking step i).

The invention also relates to a product obtainable by the treatment process according to the invention.

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

According to the present invention, the expressions "included between" and "are equivalent and mean that the limits of the intervals are included in the ranges of values stated. If this is not the case, and if the limit value is not included in the range, the present invention will give such a description.

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

Hereinafter, specific and/or preferred embodiments of the present invention may be described. Where technically feasible, they may be implemented individually or combined together without limiting the combination.

Hereinafter, the family of chemical elements is given according to CAS taxonomy (CRC Handbook of Chemistry and Physics, CRC Press publication, master code D.R.Lide, 81 th edition, 2000-2001). For example, group VIII according to CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

The metal content was measured by X-ray fluorescence.

Detailed Description

Raw materials

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, in particular plastic waste from collection and sorting channels. It comprises in particular a mixture of hydrocarbon-based compounds, in particular paraffins, mono-and/or di-olefins, naphthenes and aromatics, these hydrocarbon-based compounds preferably having a boiling point below 700 ℃ and preferably below 550 ℃. Plastic pyrolysis oils may also, and often do, contain impurities such as metals, particularly silicon and iron, and halogenated compounds, particularly chlorinated compounds. These impurities may be present in high levels in plastic pyrolysis oil, for example up to 350 ppm by weight or even 700 ppm by weight or even 1000 ppm by weight of halogen elements provided by halogenated compounds, up to 100 ppm by weight or even 200 ppm by weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, late transition metals and metalloids may be compared to contaminants of metallic nature, referred to as metals or metallic elements or semi-metallic elements. In particular, the metal or metallic element or semi-metallic element that may be contained in the oil obtained from the pyrolysis of plastic waste includes silicon, iron or both elements. The plastic pyrolysis oil may also contain other impurities, such as, in particular, heteroatoms provided by sulfur compounds, oxygen compounds and/or nitrogen compounds, which are generally present in amounts of less than 10000 ppm by weight heteroatoms, preferably less than 4000 ppm by weight heteroatoms.

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

The plastic pyrolysis oil may be obtained by a thermal catalytic pyrolysis process or may be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

Pretreatment (optional)

The feedstock comprising plastic pyrolysis oil may advantageously be pretreated in an optional pretreatment step a 0) prior to the selective hydrogenation step a) to obtain a pretreated feedstock fed to step a).

This optional pretreatment step a 0) makes it possible to reduce the amount of contaminants, in particular the amount of silicon, that may be present in the feedstock comprising plastic pyrolysis oil. Thus, the optional step a 0) of pretreatment of the feedstock comprising plastic pyrolysis oil is advantageously carried out, in particular when the feedstock comprises more than 50 wt ppm, in particular more than 20 wt ppm, more in particular more than 10 wt ppm, or even more than 5 wt ppm of metallic elements, and in particular when the feedstock comprises more than 20 wt ppm of silicon, more in particular more than 10 wt ppm, or even more than 5 wt ppm, and even more in particular more than 1.0 wt ppm of silicon.

The optional pretreatment step a 0) may be carried out by any method known to the person skilled in the art for reducing the amount of contaminants. It may in particular comprise a filtration step and/or a washing with water step and/or an adsorption step.

According to a variant, the optional pretreatment step a 0) is carried out in an adsorption section operating in the presence of at least one adsorbent. The optional pretreatment step a 0) is carried out at a temperature of from 0 to 150 ℃, preferably from 5 to 100 ℃, and at an absolute pressure of from 0.15 to 10.0MPa, preferably from 0.2 to 1.0MPaUnder pressure. The adsorption stage advantageously has a specific surface area of at least one of greater than or equal to 100m ² /g, preferably greater than or equal to 200m ² The adsorbent of/g, preferably an alumina-type adsorbent. The specific surface area of the at least one adsorbent is advantageously less than or equal to 600m ² /g, in particular less than or equal to 400m ² And/g. The specific surface area of the adsorbent is the surface area measured by the BET method, i.e. by nitrogen adsorption according to the standard ASTM D3663-78 established by the Brunauer-Emmett-Teller method described in journal The Journal of the American Chemical Society,60, 309 (1938).

Advantageously, the adsorbent comprises less than 1% by weight of metallic elements, and preferably is free of metallic elements. The term "metallic element of the adsorbent" is understood to mean an element of groups 6-10 of the periodic table (new IUPAC classification).

Optionally said adsorption section of step a 0) comprises at least one adsorption column containing said adsorbent, preferably at least two adsorption columns, preferably two to four adsorption columns. When the adsorption section comprises two adsorption columns, one mode of operation may be a mode called "switching" operation according to a specific term, wherein one column is on-line, i.e. in use, and the other column is ready for use. When the adsorbent of the on-line column fails, the column is isolated and the standby column is brought on-line, i.e. in use. The spent adsorbent may then be regenerated in situ and/or replaced with fresh adsorbent so that once another column is isolated, the column containing it may be brought online again.

Another mode of operation is with at least two columns operating in series. When the adsorbent of the tower located at the top fails, the first tower is isolated and the failed adsorbent is regenerated in situ or replaced with fresh adsorbent. The tower is then put back on-line at the last location and so on. This mode of operation is referred to as a replaceable mode, or PRS for replaceable reactor systems, or "lead and lag" according to a proprietary terminology. The combination of at least two adsorption columns makes it possible to overcome possible and potentially rapid poisoning and/or adsorbent plugging due to the combined action of metal contaminants, diolefins, gums obtained from diolefins and insoluble substances that may be present in the plastic pyrolysis oil to be treated. The reason for this is that 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 making it possible to reduce the risk of clogging and thus avoid the stopping of the unit due to clogging, to control costs and limit the consumption of adsorbent.

The optional pretreatment step a 0) may also optionally be fed with at least a portion of the recycle stream, which is advantageously obtained from step h) of the process, as a mixture with the feedstock comprising plastic pyrolysis oil or separately from the feedstock comprising plastic pyrolysis oil.

The optional pretreatment step a 0) thus makes it possible to obtain a pretreated feedstock, which is then fed to the selective hydrogenation step a).

Selective hydrogenation step a)

According to the invention, the process comprises a step a) of selective hydrogenation of a feedstock comprising a plastic pyrolysis oil, in the presence of hydrogen, under hydrogen pressure and temperature conditions such that the feedstock can be maintained in the liquid phase, and in an amount of soluble hydrogen just necessary for the selective hydrogenation of the diolefins present in the plastic pyrolysis oil. Thus, the selective hydrogenation of the diolefins in the liquid phase makes it possible to avoid or at least limit the formation of "colloids", i.e. the polymerization of diolefins and thus the formation of oligomers and polymers, which can clog the reaction section of the hydrotreatment step b). The selective hydrogenation step a) makes it possible to obtain a hydrogenation effluent, i.e. an effluent having a reduced olefin content, in particular a diolefin content, preferably free of diolefins.

According to the invention, the selective hydrogenation step a) is fed at least with the feedstock comprising plastic pyrolysis oil or with the pretreated feedstock obtained from the optional pretreatment step a 0), and comprises hydrogen (H) ₂ ) Is carried out in the reaction section of the gas stream of (a). Optionally, the reaction section of step a) may also be fed with at least a portion of the recycle stream, which is advantageousObtained from step d) or optionally step h), as a mixture with the optionally pretreated feedstock or separately from the optionally pretreated feedstock, advantageously directly fed at the inlet of at least one reactor of the reaction section of step a). Introducing at least a portion of the recycle stream into the reaction section of the selective hydrogenation step a) advantageously makes it possible to dilute impurities of the optionally pretreated feedstock and to control in particular the temperature in the reaction section.

The reaction section comprises a hydrogen partial pressure of 1.0 to 10.0MPa absolute, preferably 1.5 to 8.0MPa absolute, and a reaction time of 0.3 to 10.0h in the presence of at least one selective hydrogenation catalyst, advantageously at a temperature of 100 to 280 ℃, preferably 120 to 260 ℃, preferably 130 to 250 ℃ ^-1 Preferably 0.5 to 5.0h ^-1 Selective hydrogenation at Hourly Space Velocity (HSV), preferably in a fixed bed. The Hourly Space Velocity (HSV) is defined herein as the ratio of the hourly volumetric flow rate of the optionally pretreated feedstock containing plastic pyrolysis oil to the volume of the one or more catalysts. Hydrogen-containing (H) gas fed to the reaction section of step a) ₂ ) The amount of gas stream of (2) is advantageously such that the hydrogen coverage is in the range 1-200Nm ³ Hydrogen/m ³ Raw materials (Nm) ³ /m ³ ) Preferably 1-50Nm ³ Hydrogen/m ³ Raw materials (Nm) ³ /m ³ ) Preferably 5-20Nm ³ Hydrogen/m ³ Raw materials (Nm) ³ /m ³ ). The hydrogen coverage is defined as the ratio (in standard m) of the volumetric flow of hydrogen employed at standard temperature and pressure conditions to the volumetric flow of "fresh" feedstock (i.e. optionally pretreated feedstock to be treated, without regard to any recycle fraction) at 15 deg.c ³ Written as Nm ³ ，H ₂ /m ³ Raw material meter). The hydrogen-containing gas stream fed to the reaction section of step a) may consist of a hydrogen supply and/or in particular recycled hydrogen obtained from the separation step d).

Advantageously, the reaction section of step a) comprises from 1 to 5 reactors. According to a particular embodiment of the invention, the reaction section comprises 2 to 5 reactors, which are operated in a replaceable mode, denoted by the term PRS or by the terms "lead and lag" for replaceable reactor systems. The combination of at least two reactors in PRS mode makes it possible to isolate one reactor, discharge spent catalyst, recharge the reactor with fresh catalyst and return the reactor to use without stopping the process. PRS techniques are described in particular in patent FR 2681871.

Advantageously, a reactor insert, such as a filter plate type reactor insert, may be used to prevent plugging of one or more reactors. An example of a filter plate is described in patent FR 3051375.

Advantageously, the at least one selective hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrodeoxygenation function.

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

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

According to another variant, the hydrodeoxygenation function comprises, and preferably consists of, at least one element of group VIII, preferably nickel. According to this variant, the content of nickel oxide is preferably from 1 to 50% by weight, preferably from 10 to 30% by weight, relative to the weight of the catalyst. Such catalysts are preferably used in their reduced form on a preferably mineral support, preferably on an alumina support.

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

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

Very preferably, in order to hydrogenate the diolefins as selectively as possible, step a) may use, in addition to the selective hydrogenation catalyst described above, at least one selective hydrogenation catalyst for step a) comprising less than 1% by weight of nickel and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, expressed as nickel oxide NiO relative to the weight of the catalyst, and molybdenum oxide MoO, expressed as molybdenum oxide MoO relative to the weight of the catalyst, on an alumina support ₃ Expressed as less than 5 wt% molybdenum and at least 0.1 wt% molybdenum, preferably 0.5 wt% molybdenum. Such a small amount of added metal catalyst is preferably placed upstream of the above selective hydrogenation catalyst.

Optionally, the feedstock comprising plastic pyrolysis oil, which has optionally been pretreated, and/or optionally pre-mixed with at least a portion of the recycle stream advantageously obtained from step d) or optionally step h), may be mixed with the gas stream comprising hydrogen before it is introduced into the reaction section.

The feedstock, which has optionally been pretreated, and/or optionally mixed with at least a portion of the recycle stream advantageously obtained from step d) or from optional step h), and/or optionally as a mixture with a gas stream, may also be heated before being introduced into the reaction section of step a), for example by heat exchange with the hydrotreated effluent from step b) in particular, to reach a temperature close to the temperature of implementation in the reaction section of its feed.

The impurities, in particular the diolefins, of the hydrogenated effluent obtained at the end of step a) are reduced in content with respect to the same impurities, in particular the diolefins, contained in the feedstock of the process. The selective hydrogenation step a) can generally convert at least 90% and preferably at least 99% of the diolefins contained in the initial feedstock. Step a) may also at least partially remove other contaminants, such as silicon. The hydrogenation effluent obtained at the end of the selective hydrogenation step a) is sent, preferably directly, to the hydrotreating step b). When at least a portion of the recycle stream obtained from optional step h) is introduced, the hydrogenation effluent obtained at the end of the selective hydrogenation step a) thus comprises one or more fractions of said recycle stream in addition to the converted feedstock.

Hydrotreating step b)

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

Advantageously, step b) comprises hydrotreating reactions well known to the person skilled in the art, more particularly reactions of hydrogenation of olefins or aromatic compounds, hydrodemetallization, hydrodesulphurisation, hydrodenitrogenation, etc.

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

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

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

Advantageously, the hydrotreatment reaction zone is carried out at a pressure equal to the pressure used in the reaction zone of the selective hydrogenation step a), but at a temperature higher than the temperature of the reaction zone of the selective hydrogenation step a). Thus, the hydrotreatment reaction stage is advantageously carried out at a hydrotreatment temperature of from 250 to 430℃and preferably from 280 to 380℃at a hydrogen partial pressure of from 1.0 to 10.0MPa absolute and at a pressure of from 0.1 to 10.0h ^-1 Preferably 0.1 to 5.0h ^-1 Preferably 0.2-2.0h ^-1 Preferably 0.2 to 0.8h ^-1 Is carried out at a space-time velocity (HSV). According to the invention, the "hydrotreating temperature" corresponds to the average temperature in the hydrotreating reaction section of step b). In particular, it corresponds to a Weight Average Bed Temperature (WABT) according to a specific term, which is well known to the person skilled in the art. The hydrotreating temperature is advantageously determined according to the catalytic system used, the equipment and its configuration. For example, the hydrotreating temperature (or WABT) is calculated as follows:

WABT＝(T _{an inlet} +2x T _{An outlet} )/3

Wherein T is _{An inlet} : temperature, T, of the hydrogenation effluent at the inlet of the hydrotreatment reaction section _{An outlet} : the temperature of the effluent at the outlet of the hydroprocessing reaction section.

The Hourly Space Velocity (HSV) is defined herein as the ratio of the hourly volumetric flow of the hydrogenation effluent obtained from step a) to the volume of the catalyst or catalysts. The hydrogen coverage in step b) is advantageously from 50 to 1000Nm ³ Hydrogen/m ³ The fresh feed to step a), preferably 50-500Nm ³ Hydrogen/m ³ The fresh feed to step a), preferably 100-300Nm ³ Hydrogen/m ³ Feeding fresh feed to step a). The hydrogen coverage is defined here as the ratio (in standard m) of the volume flow of hydrogen employed under standard temperature and pressure conditions to the volume flow of fresh feedstock fed to step a), i.e. feedstock comprising plastic pyrolysis oil or optionally already pretreated feedstock fed to step a) ³ Is denoted as Nm ³ ，H ₂ /m ³ Fresh raw materials). The hydrogen may consist of the feed and/or recycled hydrogen obtained in particular from separation step d).

Preferably, the further gas stream comprising hydrogen is advantageously introduced into the inlet of each reactor, which is operated in particular in series, and/or into the inlet of each catalytic bed starting from the second catalytic bed of the hydroprocessing reaction section. These additional gas streams are also referred to as cooling streams. They allow control of the temperature in the hydroprocessing reactor where the reactions involved are typically highly exothermic.

Advantageously, the hydrotreating catalyst used in the step b) may be selected from known hydrodemetallization, hydrotreating or silicon removal catalysts, in particular catalysts for treating petroleum fractions, and combinations thereof. Known hydrodemetallization catalysts are for example those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known hydrotreating catalysts are for example those described in patent EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976. Known silicon scavenging catalysts are for example those described in patent applications CN 102051202 and US 2007/080099.

In particular, the hydrotreating catalyst comprises a support, preferably a mineral support, and at least one metal element having a hydrodeoxygenation function. The metal element having a hydrodeoxygenation function advantageously comprises at least one element of group VIII, preferably chosen from nickel and cobalt, and/or at least one element of group VIB, preferably chosen from molybdenum and tungsten. The total content of oxides of the group VIB and group VIII metal elements is preferably 0.1 wt.% to 40 wt.%, preferably 5 wt.% to 35 wt.%, relative to the total weight of the catalyst. The weight ratio of the one or more group VIB metals to the one or more group VIII metals expressed as metal oxides is preferably from 1.0 to 20, preferably from 2.0 to 10. For example, the hydrotreating reaction section of step b) of the process comprises a hydrotreating catalyst comprising 0.5 to 10 wt.% nickel, preferably 1 to 8 wt.% nickel, expressed as nickel oxide NiO relative to the total weight of the hydrotreating catalyst, and molybdenum oxide M0O, expressed as molybdenum oxide M0O relative to the total weight of the hydrotreating catalyst, on a mineral support ₃ Expressed as 1.0 to 30 wt% molybdenum, preferably 3.0 to 29 wt% molybdenum.

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

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

Advantageously, the hydrotreating catalyst used in step b) of the process has a diameter of greater than or equal to 250m ² /g, preferably greater than or equal to 300m ² Specific surface area per gram. The specific surface area of the hydrotreating catalyst is advantageously less than or equal to 800m ² /g, preferably less than or equal to 600m ² /g, in particular less than or equal to 400m ² And/g. The specific surface area of the hydrotreating catalyst is measured by the BET method, i.e., by nitrogen adsorption according to standard ASTM D3663-78 established by the Brunauer-Emmett-Teller method described in journal The Journal of the American Chemical Society,60, 309 (1938). This specific surface area makes it possible to further improve the removal of contaminants, in particular metals such as silicon.

According to another aspect of the invention, the hydrotreating catalyst as described above further comprises one or more organic compounds containing oxygen and/or nitrogen and/or sulfur. Such catalysts are generally referred to by the term "additivated catalysts". Typically, the organic compound is selected from compounds comprising one or more chemical functional groups selected from carboxyl, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional groups, or compounds or sugars comprising a furan ring.

The hydrotreating step b) advantageously allows an optimized treatment of the hydrogenation effluent obtained from step a). It makes it possible in particular to maximize the hydrogenation of the unsaturated bonds of the olefin compounds present in the hydrogenation effluent obtained from step a), the hydrodemetallization of said hydrogenation effluent and the removal of metals, in particular silicon, still present in the hydrogenation effluent. The hydrotreating step b) also allows Hydrodenitrogenation (HDN) of the hydrogenation effluent, i.e. the conversion of nitrogen-containing species still present in the hydrogenation effluent. Preferably, the hydrotreated effluent obtained from step b) has a nitrogen content of less than or equal to 10 wt-ppm.

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

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

- (b 1) two fixed bed reactors operating in switched or replaceable mode, preferably in PRS mode, each of the two reactors preferably having a catalytic bed advantageously containing a hydrotreating catalyst, preferably selected from known hydrodemetallization or silicon removal catalysts and combinations thereof, and

- (b 2) at least one fixed bed reactor, preferably one reactor, located downstream of the two reactors (b 1) and advantageously operating in series with the two reactors (b 1), the fixed bed reactors (b 2) comprising one to five catalytic beds arranged in series and each comprising one to ten hydrotreating catalysts, wherein at least one of the hydrotreating catalysts advantageously comprises a support and at least one metallic element, preferably comprising at least one group VIII element, preferably selected from nickel and cobalt, and/or at least one group VIB element, preferably selected from molybdenum and tungsten.

Optionally, step b) may comprise a heating section downstream of the hydrotreating reaction section, and wherein the hydrotreated effluent obtained from step a) is heated to a temperature suitable for hydrotreating, i.e. a temperature of 250 to 430 ℃, said optional heating section may thus comprise one or more exchangers, preferably allowing heat exchange between the hydrotreated effluent and the hydrotreated effluent, and/or a preheating furnace.

Advantageously, the hydrotreating step b) allows complete hydrogenation of the olefins present in the initial feedstock and those which can be obtained after the selective hydrogenation step a), but also allows at least partial conversion of other impurities present in the feedstock, such as aromatic compounds, metal compounds, sulphur compounds, nitrogen compounds, halogen compounds (in particular chlorine compounds) and oxygen compounds. Step b) may further reduce the content of contaminants, such as metals, in particular silicon.

Hydrocracking step c) (first hydrocracking step)

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

Advantageously, step c) comprises hydrocracking reactions well known to the person skilled in the art and more particularly makes it possible to convert heavy compounds, for example compounds having a boiling point greater than 175 ℃, into compounds having a boiling point less than or equal to 175 ℃ contained in the hydrotreated effluent obtained from step b). Other reactions may be subsequently carried out, such as hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulfurization, hydrodenitrogenation, and the like.

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

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

Said hydrocracking reaction stage is fed at least with said hydrotreated effluent obtained from step b) and with a hydrogen-containing gas stream, advantageously into the first catalytic bed of the first functional reactor.

Advantageously, the hydrocracking reaction section is carried out at a pressure equal to the pressure used in the reaction section of the selective hydrogenation step a) or the hydrotreating step b).

Thus, the hydrocracking reaction stage is advantageously carried out at a hydrotreating temperature of from 250 to 480 ℃, preferably from 320 to 450 ℃, at a hydrogen partial pressure of from 1.5 to 25.0MPa absolute, preferably from 2 to 20MPa absolute, and at a hydrogen partial pressure of from 0.1 to 10.0h ^-1 Preferably 0.1 to 5.0h ^-1 Preferably 0.2 to 4 hours ^-1 Is carried out at a space-time velocity (HSV). According to the invention, the "hydrocracking temperature" corresponds to the average temperature in the hydrocracking reaction section of step c) and step f), respectively. In particular, it corresponds to a Weight Average Bed Temperature (WABT) according to a specific term, which is well known to the person skilled in the art. The hydrocracking temperature is advantageously determined according to the catalytic system used, the equipment and its configuration. For example, the hydrocracking temperature (or WABT) is calculated as follows:

WABT＝(T _{An inlet} +2xT _{An outlet} )/3

Wherein T is _{An inlet} : temperature, T, of the hydrogenation effluent at the inlet of the hydrocracking reaction section _{An outlet} : temperature of the effluent at the outlet of the hydrocracking reaction section.

The Hourly Space Velocity (HSV) is defined herein as the ratio of the hourly volumetric flow of the hydrogenation effluent obtained from step a) to the volume of the catalyst or catalysts. The hydrogen coverage in step c) is advantageously from 80 to 2000Nm ³ Hydrogen/m ³ Fresh feed to step a), preferably 200-1800Nm ³ Hydrogen/m ³ Feeding fresh feed to step a). Hydrogen coverage is defined herein as hydrogen employed under standard temperature and pressure conditionsThe ratio of the volumetric flow to the volumetric flow of fresh feedstock (i.e. feedstock comprising plastic pyrolysis oil or optionally pretreated feedstock fed to step a) fed to step a) (at standard m ³ Is denoted as Nm ³ ，H ₂ /m ³ Fresh raw materials). The hydrogen may consist of the feed and/or recycled hydrogen obtained in particular from separation step d).

Preferably, the further gas stream comprising hydrogen is advantageously introduced into the inlet of each reactor, which is operated in particular in series, and/or into the inlet of each catalytic bed starting from the second catalytic bed of the hydrocracking reaction section. These additional gas streams are also referred to as cooling streams. They allow control of the temperature in the hydrocracking reactor where the reactions involved are typically highly exothermic.

In embodiments where it is possible to maximize the production of naphtha fractions comprising compounds having a boiling point of less than or equal to 175 ℃, the operating conditions used in the hydrocracking step c) are typically such that a single pass conversion of more than 15 wt.% and even more preferably from 20 wt.% to 95 wt.% can be obtained, converting it to a product having a boiling point of less than 175 ℃, preferably less than 160 ℃ and preferably less than 150 ℃ of at least 80% by volume.

Thus, the hydrocracking step c) does not allow to convert all compounds having a boiling point greater than 175 ℃ into compounds having a boiling point less than or equal to 175 ℃. After the fractionation step e), a more or less large fraction of the compounds having a boiling point of more than 175 ℃ is thus retained and sent to the second hydrocracking step f).

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

The one or more hydrocracking catalysts used in the hydrocracking step c) are conventional hydrocracking catalysts known to the person skilled in the art, of the bifunctional type combining an acid function and a hydro-dehydrogenation function and optionally at least one binder matrix. The acid function is defined by a large surface area (typically 150-800m ² Support, e.g. halogenated, in particular chlorinated or fluorinated, alumina, boron and aluminium oxide combinations, amorphous silica-alumina and zeolite. The hydro-dehydrogenation function is provided by at least one metal of group VIB of the periodic table and/or at least one metal of group VIII.

Preferably, the one or more hydrocracking catalysts used in step c) comprise a hydro-dehydrogenation functionality comprising at least one group VIII metal selected from the group consisting of iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, preferably selected from cobalt and nickel. Preferably, the one or more catalysts further comprise at least one group VIB metal selected from chromium, molybdenum and tungsten, alone or as a mixture, and preferably selected from molybdenum and tungsten. Preferred are hydro-dehydrogenation functionalities of the NiMo, niMoW or NiW type.

Preferably, the content of group VIII metal in the one or more hydrocracking catalysts is advantageously from 0.5 to 15% by weight, preferably from 1 to 10% by weight, expressed as a percentage by weight of oxide relative to the total weight of the catalyst.

Preferably, the content of group VIB metals in the one or more hydrocracking catalysts is advantageously from 5 to 35 wt%, preferably from 10 to 30 wt%, expressed as a weight percentage of oxides relative to the total weight of the catalyst.

The one or more hydrocracking catalysts used in step c) may optionally further comprise at least one promoter element selected from phosphorus, boron and silicon, optionally at least one group VIIA element (preferably chlorine and fluorine), optionally at least one group VIIB element (preferably manganese), and optionally at least one group VB element (preferably niobium) deposited on the catalyst.

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

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

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

When the catalyst comprises zeolite, the zeolite content of the one or more hydrocracking catalysts is advantageously from 0.1 to 80% by weight, preferably from 3 to 70% by weight, expressed as a percentage of zeolite relative to the total weight of the catalyst.

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

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

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

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

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

According to another aspect of the invention, the hydrocracking catalyst as described above further comprises one or more organic compounds containing oxygen and/or nitrogen and/or sulfur. Such catalysts are generally referred to by the term "additivated catalysts". Typically, the organic compound is selected from compounds comprising one or more chemical functional groups selected from carboxyl, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional groups, or compounds or sugars comprising a furan ring.

The preparation of the catalysts of steps a), b) or c) is known and generally comprises the steps of impregnating the support with a group VIII metal and a group VIB metal (if present) and optionally phosphorus and/or boron, followed by drying and then optionally calcining. In the case of catalysts with additives, the preparation is generally carried out by simple drying after the introduction of the organic compound without calcination. The term "calcination" refers herein to a heat treatment in a gas comprising air or oxygen at a temperature of greater than or equal to 200 ℃. The catalyst is typically sulfided to form the active material before it is used in the process step. The catalyst of step a) may also be a catalyst used in its reduced form, thus involving a reduction step in its preparation.

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

Separation step d)

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

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

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

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

This separation step d) makes it possible in particular to remove ammonium chloride salts released by hydrogenation of chlorinated compounds, in particular in the form of HCl, during step b), followed by dissolution in water, and by hydrogenation of nitrogen-containing compounds, in particular in the form of NH, during step b) ₃ The reaction between ammonium ions, which is generated in form and/or provided by injection of an amine, followed by dissolution in water, is formed and thus limits the risk of clogging due to precipitation of ammonium chloride salts, in particular in the transfer line and/or in the section of the process of the invention and/or in the transfer line of the steam cracker. It also makes it possible to remove hydrochloric acid formed by the reaction of hydrogen ions and chloride ions.

Depending on the content of chlorinated compounds in the initial feedstock to be treated, a stream containing amines, such as monoethanolamine, diethanolamine and/or monoethanolamine, may be injected upstream of the selective hydrogenation step a), between the selective hydrogenation step a) and the hydrotreating step b) and/or between the hydrocracking step c) and the separation step d), preferably upstream of the selective hydrogenation step a), to ensure that a sufficient amount of ammonium ions combines with chloride ions formed during the hydrotreating step, so that the formation of hydrochloric acid and thus corrosion downstream of the separation stage can be limited.

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

The separation step d) is advantageously carried out at a temperature of 50 to 370 ℃, preferably 100 to 340 ℃, preferably 200 to 300 ℃. Advantageously, the separation step d) is carried out at a pressure close to that used in step a) and/or b) and/or c), preferably from 1.0 to 10.0MPa, to promote the recycling of the hydrogen.

The washing/separation stage of step d) may be carried out at least partly in a common or separate washing and separation apparatus, which apparatus is well known (separation vessels, pumps, heat exchangers, washing towers, etc. which may be operated at various pressures and temperatures).

In an optional embodiment of the invention, in addition to or separate from the other described embodiments of the invention, the separation step d) comprises injecting an aqueous solution into the hydrocracking effluent obtained from step c), followed by a washing/separation stage, which advantageously comprises a separation stage for obtaining at least one aqueous effluent loaded with ammonium salt, a washed hydrocarbon-based liquid effluent and a partly washed gaseous effluent. The aqueous effluent loaded with ammonium salt and the washed hydrocarbon-based liquid effluent may then be separated in a decanting vessel to obtain the hydrocarbon-based effluent and the aqueous effluent. The partially scrubbed gaseous effluent can be introduced in parallel into a scrubbing column in which it is recycled counter-currently with respect to an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrocracking effluent, which makes it possible to at least partially, preferably completely, remove the hydrochloric acid contained in the partially scrubbed gaseous effluent and thus obtain the gaseous effluent, preferably substantially comprising hydrogen, and an acidic aqueous stream. The aqueous effluent obtained from the decanting vessel may optionally be mixed with the acidic aqueous stream and optionally used as a mixture with the acidic aqueous stream in a water recycle loop to feed to separation step d), the aqueous solution entering upstream of the washing/separation stage and/or the aqueous stream in the washing column. The water recirculation loop may include a supply of water and/or alkaline solution and/or a drain for removal of dissolved salts.

In another optional embodiment of the invention, alone or in combination with other described embodiments of the invention, the separation step d) may advantageously comprise a "high pressure" washing/separation section operating at a pressure close to that of the selective hydrogenation step a) and/or the hydrotreating step b) and/or the hydrocracking step c) to promote the recycling of hydrogen. The optional "high pressure" section of step d) may comprise a "low pressure" section in order to obtain a hydrocarbon-based liquid fraction free of a part of the dissolved gas at high pressure and which is intended to be treated directly in the steam cracking process or optionally sent to fractionation step e).

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

Passing part or all, preferably all, of the hydrocarbon-based effluent obtained from separation step d) to fractionation step e)

Fractionation step e)

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

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

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

According to one embodiment, step e) may be carried out in a section advantageously comprising at least one stripper provided with a reflux loop comprising a reflux vessel. The stripper is fed with a liquid effluent based on hydrocarbons obtained from step d) and a steam stream. The liquid hydrocarbon-based effluent obtained from step d) may optionally be heated before entering the stripper. Thus, the lightest compounds are entrained overhead and enter a reflux loop comprising a reflux vessel in which the gas/liquid separation takes place. The gas phase comprising light hydrocarbons is withdrawn from the reflux vessel as a gas stream. It is advantageous to withdraw from the reflux vessel a naphtha fraction comprising compounds having a boiling point of less than or equal to 175 ℃. The hydrocarbon fraction comprising compounds having a boiling point of greater than 175 ℃ is advantageously withdrawn at the bottom of the stripper.

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

The naphtha fraction containing compounds having a boiling point less than or equal to 175 ℃ may be sent, in whole or in part, to a steam cracking unit at the outlet of which olefins may be (re) formed to participate in the formation of the polymer. It may also be sent to a fuel tank, for example a naphtha tank, or may be partly sent to the recycling step h).

The hydrocarbon fraction comprising compounds having a boiling point of more than 175 ℃ is (as such) at least partly sent to the second hydrocracking step f).

According to a preferred embodiment, the naphtha fraction comprising compounds having a boiling point of less than or equal to 175 ℃ is sent wholly or partly to a steam cracking unit, while the fraction comprising compounds having a boiling point of greater than 175 ℃ is sent to the hydrocracking step f).

In another embodiment, the optional fractionation step e) may be such that, in addition to the gas stream, a naphtha fraction comprising compounds having a boiling point of less than or equal to 175 ℃, preferably 80-175 ℃, and a kerosene fraction comprising compounds having a boiling point of more than 175 ℃ and less than 280 ℃, even a diesel fraction comprising compounds having a boiling point of more than 280 ℃ and less than 385 ℃, and a hydrocarbon fraction comprising compounds having a boiling point of more than or equal to 385 ℃ are obtained, referred to as heavy hydrocarbon fraction. The naphtha fraction may be sent, in whole or in part, to a steam cracking unit and/or to a naphtha pool obtained from a conventional petroleum-based feedstock; it may also be sent to the recycling step h); the kerosene fraction and/or diesel fraction may also be sent in whole or in part to a steam cracking unit, or to a kerosene or diesel tank respectively obtained from conventional petroleum-based feedstocks, or recycled back to the process in the same way as the naphtha fraction; the heavy fraction may be at least partially sent to a second hydrocracking step f).

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

The gas fraction or fractions obtained from the fractionation step e) may be subjected to additional purification or purification and separation or separations to recover at least light hydrocarbons, in particular ethane, propane and butanes, which may advantageously be fed separately or as a mixture to a furnace of the steam cracking step i) to increase the overall yield of olefins.

Hydrocracking step f) (second hydrocracking step)

According to the invention, the treatment process comprises subjecting at least a portion of the hydrocarbon fraction comprising compounds having a boiling point greater than 175 ℃ obtained from step e) to a second hydrocracking step f), advantageously in a fixed bed, in the presence of hydrogen and at least one hydrocracking catalyst, to obtain a second hydrocracking effluent.

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

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

The hydrocracking reaction section is fed with at least a part of the fraction comprising compounds having a boiling point of more than 175 ℃ and a hydrogen-containing gas stream, advantageously fed into the first catalytic bed of the first functional reactor.

Advantageously, the second hydrocracking reaction zone is operated at a pressure equal to the pressure used in the reaction zone of the selective hydrogenation step a) or the hydrotreating step b) or the first hydrocracking step c).

Thus, the hydrocracking reaction stage is advantageously carried out at a hydrotreating temperature of from 250 to 480 ℃, preferably from 320 to 450 ℃, at a hydrogen partial pressure of from 1.5 to 25.0MPa absolute, preferably from 3 to 20MPa absolute, and at a hydrogen partial pressure of from 0.1 to 10.0h ^-1 Preferably 0.1 to 5.0h ^-1 Preferably O.2-4h ^-1 Is operated at a space velocity (HSV). The Hourly Space Velocity (HSV) is defined herein as the ratio of the hourly volumetric flow of the hydrogenation effluent obtained from step a) to the volume of the catalyst or catalysts. The hydrogen coverage in step f) is advantageously from 80 to 2000Nm ³ Hydrogen/m ³ Fresh feed to step a), preferably 200-1800Nm ³ Hydrogen/m ³ Feeding fresh feed to step a). The hydrogen coverage is defined here as the ratio (in standard m) of the volume flow of hydrogen employed under standard temperature and pressure conditions to the volume flow of fresh feedstock (i.e. feedstock comprising plastic pyrolysis oil) fed to step a) or optionally already pretreated feedstock fed to step a) ³ Is denoted as Nm ³ ，H ₂ /m ³ Fresh raw materials). The hydrogen may consist of the feed and/or recycled hydrogen obtained in particular from separation step d).

These operating conditions used in step f) of the process according to the invention generally make it possible to obtain a single pass conversion of greater than 15% by weight and even more preferably from 20% by weight to 80% by weight, converting it into a product comprising at least 80% by volume of compounds having a boiling point of less than or equal to 175 ℃, preferably less than 160 ℃ and preferably less than 150 ℃. However, the per pass conversion in step f) is kept medium to maximize the selectivity to naphtha fraction compounds (boiling point less than or equal to 175 ℃, especially 80 to less than or equal to 175 ℃). The single pass conversion is limited by the use of a high recycle ratio in the second hydrocracking step loop. The ratio is defined as the ratio of the flow of feed from step f) to the flow of feed from step a), which is preferably 0.2-4, preferably 0.5-2.5.

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

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

Optionally, step f) may comprise a heating section upstream of the hydrocracking reaction section, and wherein the hydrocarbon fraction comprising compounds having a boiling point of more than 175 ℃ obtained from step e) is heated to a temperature suitable for hydrocracking, i.e. a temperature of 250 to 480 ℃. The optional heating section may thus comprise one or more exchangers and/or preheat furnaces.

Step g) of recycling the second hydrocracking effluent

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

The effluent may be installed in the recycle of the second hydrocracking effluent obtained from step f). Depending on the operating conditions of the process, the discharge may be from 0 to 10% by weight, preferably from 0.5 to 5% by weight, of the hydrocracking effluent obtained from step f) relative to the incoming feedstock.

Step h) (optionally) recycling the hydrocarbon-based effluent from step d) and/or the naphtha fraction having a boiling point of less than or equal to 175 ℃ from step e)

The process according to the invention may comprise a recycling step h) in which a portion of the hydrocarbon-based effluent obtained from the separation step d) or of the naphtha fraction having a boiling point of less than or equal to 175 ℃ obtained from the fractionation step e) is recovered to constitute a recycle stream which is sent upstream of or directly into at least one of the reaction steps of the process according to the invention, in particular into the selective hydrogenation step a) and/or the hydrotreating step b). Optionally, a portion of the recycle stream may be sent to an optional pretreatment step a 0). Preferably, the method according to the invention comprises a recycling step h).

Preferably, at least a portion of the hydrocarbon-based effluent obtained from separation step d) or at least a portion of the naphtha fraction having a boiling point of less than or equal to 175 ℃ obtained from fractionation step e) is fed to hydrotreating step b).

Advantageously, the amount of recycle stream is adjusted so that the weight ratio between recycle stream and feedstock comprising plastic pyrolysis oil, i.e. feedstock to be treated fed to 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 preferably greater than or equal to 0.1. Very preferably, the amount of the recycle stream is adjusted such that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is in the range of 0.2 to 5.

Advantageously, for the initial stages of the process, the hydrocarbon fraction external to the process can be used as recycle stream. The person skilled in the art knows how to select the hydrocarbon fraction.

Recycling a portion of the resulting product into or upstream of at least one reaction step of the process according to the invention advantageously makes it possible to dilute the impurities first and to control the temperature in one or more reaction steps in which the reaction involved may be highly exothermic second.

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

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

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

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

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

-the total content of metallic elements is less than or equal to 5.0 ppm by weight, preferably less than or equal to 2.0 ppm by weight, preferably less than or equal to 1.0 ppm by weight, and preferably less than or equal to 0.5 ppm by weight, wherein:

A content of elemental silicon (Si) of less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.6 ppm by weight, and

the content of iron element (Fe) is less than or equal to 100 ppb by weight,

a sulfur content of less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight,

a nitrogen content of less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight, preferably less than or equal to 5 ppm by weight,

an asphaltene content of less than 5.0 ppm by weight,

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

the content of olefinic compounds (mono-and diolefins) is less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.1% by weight.

The content is given in relative weight concentrations, weight percent (%), parts per million by weight (ppm) or parts per billion by weight (ppb) relative to the total weight of the stream under consideration.

The process according to the invention thus makes it possible to treat plastic pyrolysis oil to obtain an effluent which can be wholly or partly injected into a steam cracking unit.

Steam cracking step i) (optional)

The naphtha fraction obtained from step e) containing compounds having a boiling point of less than or equal to 175 ℃ may be sent in whole or in part to the steam cracking step i).

Advantageously, the one or more gaseous fractions obtained from the separation step d) and/or the fractionation step e) and containing ethane, propane and butane may also be sent, in whole or in part, to the steam cracking step i).

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

The effluent from the various steam cracking furnaces is typically recombined prior to separation to form the effluent. It should be understood that the steam cracking step i) comprises a steam cracking furnace, but also comprises sub-steps related to steam cracking, which are well known to the person skilled in the art. These sub-steps may include, inter alia, heat exchangers, columns and catalytic reactors, and recycling to the furnace. The column typically allows fractionation of the effluent to recover at least one light fraction comprising hydrogen and compounds containing 2 to 5 carbon atoms, and a fraction comprising pyrolysis gasoline, and optionally a fraction comprising pyrolysis oil. The column allows for the separation of the various components of the fractionated light fraction to recover at least one ethylene rich fraction (C2 fraction) and a propylene rich fraction (C3 fraction) and optionally a butene rich fraction (C4 fraction). The catalytic reactor in particular allows selective hydrogenation of C2, C3 or even C4 fractions and pyrolysis gasoline. It is advantageous to recycle saturated compounds, especially saturated compounds containing 2 to 4 carbon atoms, to the steam cracking furnace to increase the overall yield of olefins.

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

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

According to a preferred embodiment, the process for treating a feedstock comprising plastic pyrolysis oil comprises, preferably in a given order, and preferably consists of, the above-described sequence of steps, i.e. a 0) pretreatment, a) selective hydrogenation, b) hydrotreating, c) hydrocracking, d) separation, e) fractionation, f) hydrocracking, g) recycling the second hydrocracking effluent into step d), g) recycling at least part of the naphtha fraction comprising compounds having a boiling point of less than or equal to 175 ℃ into steps a) and/or b), and steam cracking step i).

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

Analysis method used

Analytical methods and/or criteria for determining the properties of various streams, in particular of the feedstock and effluent to be treated, are known to the person skilled in the art. They are listed in particular below:

TABLE 1

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Drawings

Information about the elements mentioned in fig. 1 enables a better understanding of the invention, while the invention is not limited to the specific embodiments illustrated in the figures. The various embodiments presented may be used alone or in combination with one another without any limitation to the combination.

FIG. 1 shows a flow chart of one embodiment of the method of the present invention, comprising:

a step a) of selectively hydrogenating a hydrocarbon-based feedstock obtained from the pyrolysis of plastic 1 in the presence of a hydrogen-rich gas 2 and optionally an amine supplied from stream 3, 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 obtained from step a) in the presence of hydrogen 5, in at least one fixed bed reactor comprising at least one hydrotreating catalyst, to obtain a hydrotreated effluent 6;

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

A separation step d) of the effluent 8 carried out in the presence of an aqueous washing solution 9, so that at least one fraction 10 comprising hydrogen, an aqueous fraction 11 containing dissolved salts and a liquid fraction 12 based on hydrocarbons can be obtained;

a step e) of fractionating the liquid fraction 12 based on hydrocarbons, so that at least one gaseous fraction 13, a naphtha fraction 14 comprising compounds having a boiling point less than or equal to 175 ℃ and a fraction 15 comprising compounds having a boiling point greater than 175 ℃ can be obtained;

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

recycling the second hydrocracking effluent 17 to the step of separating step d).

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

At the end of step e), at least a portion of the naphtha fraction 14 containing compounds having a boiling point less than or equal to 175 ℃ is sent to a steam cracking process (not shown).

Optionally, a portion of the naphtha fraction 14 comprising compounds having a boiling point of less than or equal to 175 ℃ obtained from step e) constitutes a recycle stream which is fed to the selective hydrogenation step a) (portion 14 a) and the hydrotreating step b) (portion 14 b).

Fig. 1 shows only the main steps and main streams for a better understanding of the present invention. It is clearly understood that all the equipment required for functioning (vessels, pumps, exchangers, furnaces, towers, etc.) exists, even though it is not shown. It will also be appreciated that, as described above, a hydrogen-rich gas stream (supplied or recycled) may be injected into the inlet of each reactor or catalytic bed, or between two reactors or catalytic beds. Methods for purifying and recycling hydrogen known to those skilled in the art may also be used.

Examples

Example 1 (according to the invention)

Feedstock 1 treated in this process was a plastic pyrolysis oil having the characteristics shown in table 2 (i.e., comprising 100 wt% of the plastic pyrolysis oil).

Table 2: characteristics of the raw materials

(1) The MAV method is described in the article: l. Twill-GarcIa et al, near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, oil & Gas Science and Technology-Rev. IFP, volume 62 (2007), phase 1, pages 57-68.

Feedstock 1 is subjected to a selective hydrogenation step a) carried out in a fixed bed reactor in the presence of hydrogen 2 and a selective hydrogenation catalyst of the NiMo type on alumina, under the conditions indicated in table 3.

Table 3: conditions for the selective hydrogenation step a)

Temperature (temperature)	℃	180
			Partial pressure of hydrogen	Absolute pressure of MPa	6.4
H ₂ HC (hydrogen volume coverage relative to feedstock volume)	Nm ³ /m ³	50
			HSV (volume flow of feedstock/volume of catalyst)	h ^-1	0.5

At the end of the selective hydrogenation step a), all the dienes initially present in the feedstock are converted.

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

Table 4: conditions of the hydrotreating step b)

Hydrotreating temperature	℃	355
			Partial pressure of hydrogen	Absolute pressure of MPa	6.2
H ₂ HC (hydrogen volume coverage relative to feedstock volume)	Nm ³ /m ³	300
			HSV (volume flow of feedstock/volume of catalyst)	h ^-1	0.5

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

Table 5: conditions of the first hydrocracking step c)

Subjecting the effluent 8 obtained from hydrocracking step c) to a separation step d) according to the invention, wherein a water stream is injected into the effluent obtained from hydrocracking step c); the mixture is then sent to separation step d) and treated in a column to scrub the acid gas. The gas fraction 10 is obtained at the top of the acid gas scrubber, while at the bottom, a two-phase separation vessel allows separation of the aqueous phase and the liquid phase. The gas scrubber and the two-phase separator operate at high pressure. The liquid phase is then sent to a low pressure vessel to recover a second gaseous fraction and a liquid effluent that are withdrawn. The liquid effluent 12 obtained at the end of the separation step d) is sent to a fractionation step e) comprising a stripper and a distillation column, to obtain a fraction having a boiling point less than or equal to 175 ℃ (PI-175 ℃ fraction) and a fraction having a boiling point greater than 175 ℃ (175 ℃ + fraction).

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

The volume flow of the 175 ℃ plus fraction obtained from fractionation step e) and sent to the second hydrocracking step f) is equal to 80% of the volume flow of the liquid effluent obtained from hydrotreating step b) and fed to the first hydrocracking step c).

The second hydrocracking step f) was carried out in a fixed bed and in the presence of hydrogen 16 and a zeolite hydrocracking catalyst comprising NiMo under the conditions indicated in table 6.

Table 6: conditions of the second hydrocracking step f)

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

Table 7 shows the total yields of the various fractions obtained at the outlet of the hydrocracking steps c) and f) at the end of the separation step d) and the fractionation step e), which comprises a stripper and a distillation column.

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

H ₂ S ^*	％m/m	0.27
			NH ₃ ^*	％m/m	0.09
C1	％m/m	0.21
			C2	％m/m	0.21
C3	％m/m	1.76
			C4	％m/m	6.34
PI-175 ℃ fraction	％m/m	93.00
			175 ℃ plus fraction	％m/m	0.50
Totals to	％m/m	102.37

Compound H ₂ S and NH ₃ Is removed mainly in the form of a salt in the aqueous phase removed in separation step d).

The treatment of the feedstock according to the steps of the invention, in particular by hydrocracking steps c) and f), makes it possible to obtain very high yields of naphtha type PI-175 ℃ fractions.

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

table 8: characteristics of PI-175 ℃ and 175 ℃ plus fractions

Both the liquid fractions PI-175 ℃ and 175 ℃ + have compositions compatible with the steam cracking unit, since:

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

they have a very low content of elemental chlorine (undetected content and content of 25 ppb by weight, respectively) below the limit required for steam cracking of the feedstock;

the metal content, in particular the iron (Fe) content, is also very low (no metal content is detected in the fraction at PI-175 ℃ C. And < 1 ppm by weight in the fraction at 175 ℃ C. + and no Fe content is detected in the fraction at PI-175 ℃ C. + and 50 ppb by weight in the fraction at 175 ℃ C.) which is lower than the limit required for the steam cracking feedstock (metal. Ltoreq.5.0 ppm by weight, very preferably. Ltoreq.1 ppm by weight; fe. Ltoreq.100 ppb by weight);

finally, they contain sulfur (fraction < 2 ppm by weight for PI-175 ℃ C., fraction < 2 ppm by weight for 175 ℃ C. + fraction) and nitrogen (fraction < 0.5 ppm by weight for PI-1 ℃ C., fraction < 3 ppm by weight for 175 ℃ C. + fraction) in amounts much lower than the limits required for steam cracking feedstocks (500 ppm by weight for S and N. Ltoreq.500 ppm by weight, preferably. Ltoreq.200 ppm by weight).

The liquid fraction PI-175 ℃ obtained is then sent to the steam cracking step h) (see table 9).

Table 9: conditions of the steam cracking step

Pressure at furnace outlet	Absolute pressure of Mpa	0.2
			Temperature of PI-175 ℃ fraction at furnace exit	℃	800
steam/PI-175 ℃ fraction ratio	kg/kg	0.6
			Furnace residence time of PI-175 ℃ fraction	s	0.3

The effluent from the various steam cracking furnaces is subjected to a separation step which enables the recycling of saturated compounds into the steam cracking furnace and yields (yield = mass% of product relative to the mass of PI-175 ℃ fraction upstream of the steam cracking step, expressed as% m/m) shown in table 10.

Table 10: yield of steam cracking step

Fractions and process for preparing the fractions		PI-175 ℃ fraction
			H ₂ ，CO，C1	％m/m	7.9
Ethylene	％m/m	34.3
			Propylene	％m/m	18.7
C4 fraction	％m/m	14.9
			Pyrolysis gasoline	％m/m	19.3
Pyrolysis oil	％m/m	4.9

Considering that the yield obtained for the liquid fraction 175 ℃ during the pyrolysis oil treatment process at the outlet of the hydrocracking step is 93% (see table 7), the total yield of the product obtained from the steam cracking step i) relative to the plastic pyrolysis oil type initial feedstock introduced into step a) can be determined:

table 11: for the PI-175 ℃ fraction, the overall process yield of the product from the steam cracking step

Fractions and process for preparing the fractions		PI-175 ℃ fraction
			H ₂ ，CO，C1	％m/m	7.4
Ethylene	％m/m	31.9
			Propylene	％m/m	17.4
C4 fraction	％m/m	13.9
			Pyrolysis gasoline	％m/m	17.9
Pyrolysis oil	％m/m	4.5

When the PI-175 ℃ fraction is sent to a steam cracking unit, the process according to the invention makes it possible to achieve a total mass yield of 31.9% and 17.4% of ethylene and propylene, respectively, with respect to the mass of the plastic pyrolysis oil type starting material.

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

Example 2 (not according to the invention)

In this example, the raw material to be treated was the same as described in example 1 (see table 2).

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

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

Table 12: yields of the various products and fractions obtained at the outlet of the hydrotreatment step b)

H ₂ S	％m/m	0.27
			NH ₃	％m/m	0.09
C1	％m/m	0.0 1
			C2	％m/m	0.02
C3	％m/m	0.09
			C4	％m/m	0.38
PI+ fraction		99.55
			Totals to	％m/m	100.05

The characteristics of the pi+ fraction (which corresponds to the liquid effluent) obtained after separation step d) are shown in table 13:

table 13: characteristics of the PI+ fraction

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The pi+ fraction obtained by the sequence of steps a), b) and d) comprises about 35% of compounds of the naphtha type having a boiling point less than or equal to 175 ℃. This low yield of naphtha type compounds having a boiling point less than or equal to 175 ℃ is due to the absence of a hydrocracking step in this example not according to the invention.

The liquid effluent fraction pi+ is sent directly to the steam cracking step i) under the conditions described in table 14.

Table 14: conditions of the steam cracking step

Pressure at furnace outlet	Absolute pressure of MPa	0.2
			Temperature of pi+ fraction at furnace outlet	℃	795
Ratio of steam/PI+ fraction	kg/kg	0.7
			Furnace residence time of pi+ fraction	S	0.3

The effluent from the steam cracking furnace was subjected to a separation step which enabled the recycling of saturated compounds into the steam cracking furnace and produced the yields shown in table 15 (yield = mass% of product relative to the mass of pi+ fraction upstream of the steam cracking step, noted as% m/m).

Table 15: yield of steam cracking step for pi+ fraction

Fractions and process for preparing the fractions		PI+ fraction
			H ₂ ，CO，C1	％m/m	8.1
Ethylene	％m/m	34.8
			Propylene	％m/m	19.0
C4 fraction	％m/m	15.1
			Pyrolysis gasoline	％m/m	18.8
Pyrolysis oil	％m/m	4.2

Considering that the yield obtained for the pi+ fraction during the pyrolysis oil treatment process at the outlet of the hydrotreatment step b) is 99.5% (see table 12), the total yield of product obtained from the steam cracking step i) relative to the plastic pyrolysis oil type initial feedstock introduced into step a) can be determined:

table 16: for the pi+ fraction, the overall process yield of the product obtained from the steam cracking step

Fractions and process for preparing the fractions		PI+ fraction
			H ₂ ，CO，Cl	％m/m	8.1
Ethylene	％m/m	34.6
			Propylene	％m/m	18.9
C4 fraction	％m/m	15.0
			Pyrolysis gasoline	％m/m	18.7
Pyrolysis oil	％m/m	4.2

When the liquid fraction pi+ is subjected to a steam cracking step, the process according to the invention makes it possible to achieve a total mass yield of ethylene and propylene of 34.6% and 18.9%, respectively, with respect to the mass of the plastic pyrolysis oil type starting material.

Claims

1. A process for treating a feedstock comprising plastic pyrolysis oil, comprising:

b) A hydrotreating step carried out in a hydrotreating reaction zone fed with at least the hydrotreating effluent obtained from step a) and a gas stream comprising hydrogen, using at least one fixed bed reactor comprising n catalytic beds, n being an integer greater than or equal to 1, each catalytic bed comprising at least one hydrotreating catalyst, said hydrotreating reaction zone being at a temperature of from 250 to 430 ℃, a hydrogen partial pressure of from 1.0 to 10.0MPa absolute and a hydrogen partial pressure of from 0.1 to 10.0h ^-1 Is used at a hourly space velocity to obtain a hydrotreated effluent;

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

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

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

4. The process according to any of the preceding claims, comprising a step a 0) of pre-treating a feedstock comprising plastic pyrolysis oil, said pre-treatment step being carried out upstream of the selective hydrogenation step a) and comprising a filtration step and/or a step of washing with water and/or an adsorption step.

5. The process according to any of the preceding claims, wherein the reaction section of step a) or b) uses at least two reactors operating in a replaceable mode.

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

7. The process according to any of the preceding claims, wherein the selective hydrogenation catalyst comprises a support selected from the group consisting of alumina, silica-alumina, magnesia, clay, and mixtures thereof, and a hydro-dehydrogenation functionality comprising at least one group VIII element and at least one group VIB element, or at least one group VIII element.

8. The process according to any of the preceding claims, wherein the hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica-alumina, magnesia, clay, and mixtures thereof, and a hydro-dehydrogenation functionality comprising at least one group VIII element and/or at least one group VIB element.

9. The process according to any of the preceding claims, wherein the hydrocracking catalyst of step c) or step f) comprises a support selected from the group consisting of halogenated alumina, a combination of boron and aluminium oxides, amorphous silica-alumina and zeolite, and a hydro-dehydrogenation functionality comprising at least one group VIB metal selected from chromium, molybdenum and tungsten, alone or as a mixture, and/or at least one group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

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

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

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

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

14. A product obtained by the process according to any one of claims 1-13.