Method for treating plastic pyrolysis oil for use in a steam cracking unit - Patent Application 20070122997

Abstract

The present invention relates to a method for treating plastic pyrolysis oil, the method comprising: a) treating a plastic pyrolysis oil in the presence of hydrogen and at least one selective hydrogenation catalyst at a temperature of 100-150°C, a hydrogen partial pressure of 1.0-10.0 MPa (absolute), and an hourly space velocity of 1.0-10.0 h -1 a) selectively hydrogenating a feedstock at a temperature between 250 and 370°C and a hydrogen partial pressure between 1.0 and 10.0 MPa (absolute) to obtain a hydrogen effluent; b) hydrotreating the hydrogen effluent in the presence of hydrogen and at least one hydrotreating catalyst at a temperature between 250 and 370°C and a hydrogen partial pressure between 1.0 and 10.0 MPa (absolute) to obtain a hydrotreated effluent; c) separating the hydrotreated effluent originating from step b) in the presence of an aqueous stream at a temperature between 50 and 370°C to obtain at least one gaseous effluent, one aqueous liquid effluent and one hydrocarbon liquid effluent.

Description

[Technical Field]

[0001] The present invention relates to a method for treating plastic pyrolysis oil to obtain a hydrocarbon effluent, the composition of which is compatible with the feedstock fed to a steam cracking unit. More particularly, the present invention relates to a method for treating a feedstock obtained from the pyrolysis of plastic waste to at least partially remove impurities, in particular olefins (mono- and di-olefins), metals, in particular silicon, and halogens, in particular chlorine, which the feedstock may contain in relatively large amounts, and to hydrogenate and upgrade the feedstock in a steam cracking unit with an increased yield of light olefins. [Background technology]

[0002] The plastics obtained from the collection and sorting channels may undergo a process of pyrolysis, in particular to obtain pyrolysis oils, which are generally combusted to produce electricity and / or used as fuel in industrial boilers or city heating.

[0003] Another route to upgrading plastic pyrolysis oils could be to use them as feedstock for steam cracking units to (re)create olefins, which are the constituent monomers of certain polymers. However, plastic waste is generally a mixture of multiple polymers, such as polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polystyrene. Furthermore, depending on the application, plastics may contain other compounds in addition to polymers, such as plasticizers, pigments, dyes, or polymerization catalyst residues. Plastic waste may also contain trace amounts of biomass, such as those originating from household waste. As a result, the oil obtained from the pyrolysis of plastic waste contains large amounts of impurities, especially diolefins, metals, especially silicon, or halogenated compounds, especially chlorine-based compounds, heteroelements, such as sulfur, oxygen, and nitrogen, and insoluble substances, often at high levels that make them incompatible with steam cracking units or units downstream of the steam cracking unit, especially polymerization and selective hydrogenation processes. These impurities may result in operability problems, particularly corrosion, coking, or catalyst deactivation problems, or incompatibility in the application of the target polymer. The presence of diolefins may also lead to instability problems in the pyrolysis oil, characterized by the formation of gums. This phenomenon is generally limited by proper containment of the feedstock. Gums and insolubles that may be present in the pyrolysis oil can cause blockage problems in the process.

[0004] Furthermore, during the steam cracking process, the yield of light olefins sought for petrochemicals, especially ethylene and propylene, is highly dependent on the quality of the feedstock sent for steam cracking. The Bureau of Mines Correlation Index (BMCI) is often used to characterize hydrocarbon fractions. Globally, the yield of light olefins increases with increasing paraffin content and / or decreasing BMCI. Conversely, the yield of unwanted heavy compounds and / or coke increases with increasing BMCI.

[0005] Patent document 1 proposes a comprehensive method for recycling plastic waste. It is very general and ranges from extreme steps of thermal decomposition of plastic waste to steam cracking steps. The method of Patent document 1 comprises, in particular, a step of hydrotreating the liquid phase obtained directly from the pyrolysis, preferably under very stringent conditions, in particular temperature-stringent conditions, for example at temperatures between 260 and 300°C, a step of separating the hydrotreated effluent, and a subsequent step of hydrodealkylation of the separated off heavy effluent, preferably at high temperatures, for example at temperatures between 260 and 400°C.

[0006] The present invention aims to overcome these drawbacks and participate in the recycling of plastics by treating the oil derived from the pyrolysis of plastics in order to purify it and to hydrotreat it, thereby obtaining a hydrocarbon effluent with a reduced content of impurities, the composition of which is compatible with the feedstock fed to the steam cracking unit, leading to an improved yield of light olefins during the steam cracking step, while in particular reducing the risk of blockages during the process for treating plastic pyrolysis oil, such as those described in the prior art, and the risk of significant coke formation and / or corrosion encountered during the process for steam cracking plastic pyrolysis oil. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2018 / 055555 Summary of the Invention [Means for solving the problem]

[0008] (Summary of the Invention) The present invention provides a method for processing a feedstock containing plastic pyrolysis oil, comprising at least the following steps: a) selective hydrogenation step; in a reaction section, a gaseous stream containing the feedstock and hydrogen is fed to a reaction section in the presence of at least one selective hydrogenation catalyst at a temperature of 100 to 250°C, a hydrogen partial pressure of 1.0 to 10.0 MPa (absolute), and an hourly space velocity of 1.0 to 10.0 h -1 obtaining a hydrogenated effluent; b) a hydrotreating step carried out in a hydrotreating reaction section comprising a fixed bed reactor containing n catalyst beds, n being an integer equal to or greater than 1, arranged in series, each containing at least one hydrotreating catalyst, wherein the hydrogenated effluent from step a) and a gaseous stream containing hydrogen are fed to the first catalyst bed of the hydrotreating reaction section at a temperature of 250-430°C, a hydrogen partial pressure of 1.0-10.0 MPa (absolute), and an hourly space velocity of 0.1-10.0 h -1 to obtain a hydrotreated effluent; c) a separation step, which involves feeding the hydrotreated effluent and the aqueous solution obtained from step b) and carrying out the separation at a temperature of 50 to 370°C to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent. The present invention relates to a method comprising:

[0009] The advantage of the process of the present invention is that it provides a precise sequence of operations that allows the oil derived from the pyrolysis of plastic waste to be freed of at least some of its impurities and hydrogenated to make it particularly compatible with processing in a steam cracking unit to be able to regenerate light olefins in improved yields that can be used as monomers in the production of polymers. The present invention also makes it possible to prevent the risk of blockage and / or corrosion of the processing unit in which the process of the present invention is carried out, a risk exacerbated by the presence of diolefins, metals and halogenated compounds in the plastic pyrolysis oil, often in large amounts.

[0010] The process of the present invention therefore makes it possible to obtain an effluent obtained from plastic pyrolysis oil that is at least partially free from the impurities of the starting plastic pyrolysis oil, thus limiting the operability problems that these impurities may cause in the steam cracking unit and / or units located downstream of the steam cracking unit, in particular the polymerization and selective hydrogenation units, such as corrosion, coking or catalyst deactivation problems. The removal of at least a portion of the impurities from the oil obtained from the pyrolysis of plastic waste also makes it possible to increase the range of applications of the target polymer, reducing its application incompatibility.

[0011] The present invention has the additional advantage of participating in the recycling of plastics and the conversion of fossil resources by making it possible to upgrade the oils resulting from their pyrolysis in a steam cracking unit: it in fact makes it possible to refine and hydrotreat these oils, which can then be introduced into a steam cracker to obtain olefins and thus remanufacture polymers.

[0012] The method also makes it possible to obtain naphtha and / or diesel fractions from feedstocks containing plastic pyrolysis oil, fractions that could be directly integrated into naphtha and / or diesel pools, respectively, obtained by refiners by refining crude oil. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Description of the embodiment) According to the present invention, "plastics pyrolysis oil" refers to an oil, advantageously in liquid form at ambient temperature, obtained from the pyrolysis of plastics, preferably plastic waste, especially from collection and sorting channels. It contains, in particular, a mixture of hydrocarbon compounds, especially paraffins, monoolefins and / or diolefins, or possibly naphthenes and aromatic compounds, preferably having a boiling point below 700°C, preferably below 550°C. Plastic pyrolysis oil may, and usually does, contain impurities, such as metals, especially silicon and iron, and halogenated compounds, especially chlorinated compounds. These impurities may be present in high concentrations in plastics pyrolysis oil, for example, up to 350 ppm by weight, or even up to 700 ppm by weight, or even up to 1000 ppm by weight of halogen elements provided by halogenated compounds, and up to 100 ppm by weight, or even up to 200 ppm by weight of metallic or semi-metallic elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals, and metalloids may be compared to metallic contaminants and are referred to as metals, metallic, or metallic elements. In particular, metals, metallic, or metallic elements that may be contained in oil obtained from the pyrolysis of plastic waste include silicon, iron, or both of these elements. Plastic pyrolysis oil may contain heteroelements, particularly those provided by other impurities such as sulfur compounds, oxygen compounds, and / or nitrogen compounds, generally in a content of less than 10,000 ppm by weight of heteroelements, preferably less than 4,000 ppm by weight of heteroelements.

[0014] According to the invention, the pressure is absolute pressure, also written abs. (absolute) and is given in MPa absolute (or MPa(absolute)).

[0015] According to the present invention, the expressions "comprised between ... and ..." and "between ... and ..." are equivalent and mean that both limits of the interval are included in the stated range of values. If this were not the case and both limits were not included in the stated range, such clarification would be provided by the present invention.

[0016] For purposes of the present invention, various ranges of parameters for a given process, such as pressure ranges and temperature ranges, may be used alone or in combination. For example, for purposes of the present invention, a preferred range of pressure values may be combined with a more preferred range of temperature values.

[0017] In the following specification, specific embodiments of the present invention may be described, which may be implemented separately or in combination together, without any limitation on the combination where this is technically feasible.

[0018] The present invention provides a method for processing a feedstock containing plastic pyrolysis oil, comprising the steps of: a) a selective hydrogenation step, advantageously carried out in a fixed bed, in which the feedstock and hydrogen are contacted in the presence of at least one selective hydrogenation catalyst, said selective hydrogenation being advantageously carried out in at least one reactor, preferably at least two reactors in series, preferably two permutable reactors of the PRS (Permutable Reactor System) type, at a temperature of 100-250°C, preferably 110-200°C, preferably 130-180°C, with a hydrogen partial pressure of 1.0-10.0 MPa (absolute) and an hourly space velocity of 1.0-10.0 h -1 obtaining at least one effluent having a reduced content of diolefins, also referred to as hydrogenated effluent; b) a hydrotreating step carried out in a fixed bed, in which the hydrogenated effluent from the selective hydrogenation step a) is contacted with hydrogen in the presence of at least one hydrotreating catalyst, carried out in at least one fixed bed reactor, advantageously comprising n catalyst beds, n being an integer greater than or equal to 1, preferably between 2 and 10, preferably between 2 and 5, arranged in series, at a temperature of 250-430°C, preferably between 280-380°C, with a hydrogen partial pressure of 1.0-10.0 MPa (absolute) and an hourly space velocity (HSV) of 0.1-10.0 h -1 , preferably 0.1 to 5.0 h -1 , preferentially 0.2 to 2.0 hours -1 , preferably 0.2 to 0.8 hours -1 and an additional gaseous stream containing hydrogen is advantageously introduced into the inlet of each catalyst bed from the second catalyst bed to obtain at least one hydrotreated effluent; c) a step of separating the hydrotreated effluent obtained from step b), comprising a washing / separation section to which the hydrotreated effluent obtained from step b) and advantageously an aqueous stream are fed, said separation step being carried out at a temperature between 50 and 370°C, preferentially between 100 and 340°C, preferably between 200 and 300°C, to obtain at least one gaseous effluent, at least one aqueous effluent and at least one hydrocarbon effluent. The present invention relates to a method comprising:

[0019] (Feed material) The feedstock for the process according to the invention comprises at least one plastic pyrolysis oil. The feedstock may consist solely of plastic pyrolysis oil(s). Preferably, the feedstock comprises at least 50% by weight, preferably 75% to 100% by weight of plastic pyrolysis oil, i.e. preferably 50% to 100% by weight, preferably 70% to 100% by weight of plastic pyrolysis oil. The feedstock for the process according to the invention may in particular comprise one or more plastic pyrolysis oils, a conventional petroleum-based feedstock, which is subsequently co-processed with the feedstock plastic pyrolysis oil.

[0020] The feedstock plastic pyrolysis oil contains hydrocarbon compounds, preferably paraffin compounds, and impurities such as, in particular, monoolefins and / or diolefins, metals, especially silicon and iron, heteroelements provided by halogenated compounds, especially chlorinated compounds, sulfur-containing compounds, oxygen-containing compounds and / or nitrogen-containing compounds. These impurities are often present in high contents, for example, up to 350 ppm by weight, even up to 700 ppm by weight, even up to 1000 ppm by weight of halogen elements provided by halogenated compounds, and up to 100 ppm by weight, even up to 200 ppm by weight of metallic or semi-metallic elements.

[0021] The feedstock containing plastic pyrolysis oil can be advantageously pre-treated in a pre-treatment step a0) prior to the selective hydrogenation step a) to obtain a pre-treated feedstock, which is then fed to step a). This pre-treatment step a0) makes it possible to reduce the amount of contaminants, particularly silicon, that may be present in the feedstock containing plastic pyrolysis oil. Therefore, step a0) of pre-treatment of the feedstock containing plastic pyrolysis oil is advantageously carried out when the feedstock contains more than 50 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 10 ppm by weight, or even more than 5 ppm by weight of metallic elements, in particular when the feedstock contains more than 20 ppm by weight, more particularly more than 10 ppm by weight, or even more particularly more than 5 ppm by weight of elements, and even more particularly more than 1.0 ppm by weight of silicon.

[0022] The pretreatment step a0) is carried out in an adsorption section prior to the selective hydrogenation step a), which is fed with the feedstock containing the plastic pyrolysis oil and operates in the presence of at least one adsorbent at a temperature of 0 to 150°C, preferably 5 to 100°C, and at a pressure of 0.15 to 10.0 MPa (absolute), preferably 0.2 to 1.0 MPa (absolute), the adsorbent preferably being of the alumina type and having a specific surface area of 100 m2 / g or more, preferably 200m 2 The specific surface area of said at least one adsorbent is advantageously 600 m 2 / g or less, especially 400m 2 / g or less. The specific surface area of the adsorbent is the surface area measured by the BET method, i.e. the specific surface area determined by nitrogen adsorption according to standard ASTM D 3663-78, established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938). Advantageously, the adsorbent contains less than 1% by weight of metallic elements, preferably no metallic elements. The term "metallic elements of the adsorbent" should be understood as referring to elements from groups 6 to 10 of the periodic table of the elements.

[0023] The adsorption section includes at least one adsorption column, preferably two adsorption columns, containing the adsorbent. When the adsorption section includes two adsorption columns, one operating mode may be called "swing," in which one of the columns is online while the other is in reserve. When the absorbent in the online column is depleted, this column is isolated, while the column in reserve is placed online. The depleted absorbent is then regenerated in situ and / or replaced with fresh absorbent, and will be replaced online again when the other column is isolated. Another operating mode is to have two columns operating in series; when the absorbent in the top column is depleted, this first column is isolated, and the depleted absorbent is either regenerated in situ or replaced with fresh absorbent. The column is then brought back online in a second position, etc. This operation is called "lead and drag," according to established terminology. The combination of two adsorption columns makes it possible to overcome possible and potentially rapid poisoning and / or blockage of the adsorbent due to the combined action of metallic contaminants, diolefins, gums and insolubles resulting from diolefins that may be present in the plastic pyrolysis oil to be treated. The presence of two adsorption columns in fact facilitates the replacement and / or regeneration of the adsorbent, advantageously without shutting down the pretreatment unit or even the process, thus reducing the risk of blockages and thus making it possible to avoid unit shutdowns due to blockages, controlling costs and limiting adsorbent consumption.

[0024] (Selective hydrogenation step a) According to the present invention, the process comprises a selective hydrogenation step a) carried out in the presence of hydrogen under conditions of hydrogen pressure and temperature that allow them to maintain a liquid phase, with the amount of soluble hydrogen just necessary for the selective hydrogenation of the diolefins present in the plastic pyrolysis oil. Selective hydrogenation of diolefins in the liquid phase therefore makes it possible to avoid or at least limit the formation of "gums" that can clog the reaction section of the subsequent hydrotreating step, i.e., the polymerization of diolefins and therefore the formation of oligomers and polymers. The selective hydrogenation step a) makes it possible to obtain a hydrogenated effluent, i.e., an effluent with a reduced content of diolefins, or even free of diolefins.

[0025] According to the invention, the selective hydrogenation step a) is carried out in a reaction section to which the feedstock comprising the plastic pyrolysis oil or the optionally pretreated feedstock obtained from the pretreatment step a0) and a gaseous stream comprising hydrogen (H2) are fed. The reaction section involves selective hydrogenation in a fixed bed in the presence of at least one selective hydrogenation catalyst, advantageously at a temperature of 100-250°C, preferably 110-200°C, preferably 130-180°C, with a hydrogen partial pressure of 1.0-10.0 MPa (absolute) and an hourly space velocity (HSV) of 1.0-10.0 h2. -1 According to step a) of the process of the present invention, the hourly space velocity (HSV) is defined as the ratio of the hourly volumetric flow rate of the feedstock comprising the (optionally pretreated) plastic pyrolysis oil to the volume of the catalyst(s). The amount of gaseous stream fed to said reaction section of step a) is advantageously determined so that the hydrogen coverage is equal to the volume (m 3 ) per 1-50Nm of hydrogen 3 (Nm 3 / m 3 ), preferably the volume of the feedstock (m 3 ) 5 to 20 Nm of hydrogen per 3 (Nm 3 / m 3) is used. Hydrogen coverage is defined as the ratio of the volumetric flow rate of hydrogen available under standard temperature and pressure conditions relative to the volumetric flow rate of the feedstock at 15°C (volume of feedstock (m 3 ) Nm of H2 per 3 Normal m written as 3 The hydrogen-containing gaseous stream fed to the reaction section of step a) may consist of recycled hydrogen, obtained in particular from the hydrogen feed and / or separation step c).

[0026] Advantageously, the reaction section of step a) comprises at least one reactor. Preferably, the reaction section comprises at least two reactors, preferably two reactors operating in a permutable system, also called "PRS" (Permutable Reactor System). The combination of two "PRS" reactors makes it possible to isolate one reactor, discharge spent catalyst, recharge the reactor with fresh catalyst and return said reactor to service without shutting down the process. The PRS technology is particularly described in patent FR2681871.

[0027] Advantageously, reactor inserts may be used to prevent clogging of the reactor(s), for example of the filter plate type, examples of which are described in patent FR3051375.

[0028] Advantageously, said at least one selective hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrodehydrogenating group.

[0029] The hydrodehydrogenation catalyst comprises, in particular, at least one group VIII element and / or at least one group VIB element. The group VIII element is preferably selected from the group consisting of nickel and cobalt. The group VIB element is preferably selected from the group consisting of molybdenum and tungsten. The total content of oxides of metallic elements from groups VIB and VIII (i.e. the sum of metallic elements from groups VIB and VIII) is preferably 1% to 40% by weight, preferentially 5% to 30% by weight, relative to the total weight of the catalyst. The weight ratio, expressed as metal oxides, between the group VIB metal(s) relative to the group VIII metal(s) is preferably 1 to 20, preferably 2 to 10. For example, the reaction section of step a) comprises a selective hydrogenation catalyst comprising 0.5% to 10% by weight of nickel, preferably 1% to 5% by weight of nickel (expressed as nickel oxide NiO relative to the weight of the catalyst), 1% to 30% by weight of molybdenum, preferably 3% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO3 relative to the weight of the catalyst) on a support, preferably a mineral support.

[0030] The support for the at least one selective hydrogenation catalyst is preferably selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof. The support may contain a dopant compound, in particular an oxide selected from the group consisting of boron oxide, especially boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide, and mixtures of these oxides. Preferably, the at least one selective hydrogenation catalyst comprises an alumina support, preferably doped with phosphorus and optionally boron. If present, phosphorus pentoxide P2O5 has a concentration of less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. If present, boron trioxide B2O3 has a concentration of less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be γ (gamma) or η (eta) alumina.

[0031] The selective hydrogenation catalyst is, for example, in the form of extrudates.

[0032] Highly preferably, the at least one selective hydrogenation catalyst used in step a) comprises less than 1% by weight of nickel, expressed as nickel oxide NiO relative to the weight of the catalyst, and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, and less than 5% by weight of molybdenum, expressed as molybdenum oxide MoO relative to the weight of the catalyst, and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, on an alumina support, in order to hydrogenate diolefins as selectively as possible.

[0033] Optionally, the feedstock comprising optionally pre-treated plastic pyrolysis oil may be mixed with a gaseous stream containing hydrogen prior to the reaction section.

[0034] The feedstock, optionally mixed with a gaseous stream, may be heated before the reaction section, for example by heat exchange, especially with a hydroprocessing effluent, to reach a temperature close to that used in the reaction section to which it feeds.

[0035] The content of impurities, especially diolefins, in the hydrogenated effluent obtained at the end of step a) is reduced relative to the content of certain impurities, especially the content of diolefins contained in the feedstock of the process.Step a) makes it possible to convert at least 90%, preferably at least 99%, of the diolefins contained in the original feedstock.Step a) also makes it possible to at least partially remove other contaminants, such as silicon.The hydrogenated effluent is preferably sent directly to hydrotreating step b).

[0036] (Hydrotreatment step b)) According to the invention, the treatment process comprises a step b) of hydrotreating, advantageously in a fixed bed, of said hydrogenated effluent obtained from step a) in the presence of hydrogen and at least one hydrotreating catalyst to obtain a hydrotreated effluent.

[0037] Advantageously, step b) is carried out in a hydrotreating reaction section comprising a fixed bed reactor containing n catalyst beds, n being an integer greater than or equal to 1, preferably between 2 and 10, preferably between 2 and 5, arranged in series and each containing at least one hydrotreating catalyst. Advantageously, at the first catalyst bed, the reaction section is fed with the hydrogenated effluent from step a) and a gaseous stream comprising hydrogen.

[0038] Advantageously, the hydrotreating reaction section is carried out at a pressure equivalent to that used in the reaction section of the selective hydrogenation step a), but at a temperature higher than that of the reaction section of the selective hydrogenation step a). The temperature at which the hydrotreating reaction section is carried out is therefore advantageously between 250 and 430°C, preferably between 280 and 380°C, with a hydrogen partial pressure of 1.0 and 10.0 MPa (absolute) and an hourly space velocity (HSV) of 0.1 and 10.0 h -1 , preferably 0.1 to 5.0 h -1 , preferentially 0.2 to 2.0 hours -1 , preferably 0.2 to 0.8 hours -1 According to step b) of the process of the invention, the hourly space velocity (HSV) is defined as the ratio of the hourly volumetric flow rate of the hydrogenated effluent obtained from step a) to the volume of the catalyst(s). The hydrogen coverage in step b) is advantageously determined by the volume (m ) of the hydrogenated effluent obtained from step a). 3 ) 50-1000Nm of hydrogen per 3 , preferably the volume (m ) of the hydrogenated effluent obtained from the selective hydrogenation step a) 3 ) 50-500Nm of hydrogen per 3 , preferably the volume (m ) of the hydrogenated effluent obtained from the selective hydrogenation step a) 3 ) 100-300Nm of hydrogen per 3 The hydrogen coverage is defined in this case as the ratio of the volumetric flow rate of hydrogen utilized under standard conditions of temperature and pressure relative to the volumetric flow rate of the hydrogenated effluent obtained from step a) (the volume (m 3 ) Nm of H2 per 3 Normal m written as 3 The hydrogen may consist of recycled hydrogen, in particular obtained from the feed and / or separation step c).

[0039] Additional gaseous streams, preferably containing hydrogen, are advantageously introduced at the inlet of each catalyst bed from the second catalyst bed. These additional gaseous streams are also called quench streams. They make it possible to control the temperature in the hydroprocessing reactor, where the reactions involved are generally highly exothermic.

[0040] Advantageously, the at least one hydrotreating catalyst used in step b) may be selected from known hydrodemetallization, hydrotreating or silicon trapping catalysts, especially those used for the treatment of petroleum fractions, and combinations thereof. Known hydrodemetallization catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known hydrotreating catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976. Known silicon trapping catalysts are, for example, those described in patent applications CN 102051202 and US 2007 / 080099.

[0041] In particular, the at least one hydrotreating catalyst comprises a support, preferably a mineral support, and at least one metallic element having hydrodehydrogenation function. The at least one metallic element having hydrodehydrogenation function advantageously comprises at least one group VIII element and / or at least one group VIB element. The group VIII element is preferably selected from the group consisting of nickel and cobalt. The group VIB element is preferably selected from the group consisting of molybdenum and tungsten. The total content of oxides of metallic elements from groups VIB and VIII is preferably between 1% and 40% by weight, preferentially between 5% and 30% by weight, relative to the total weight of the catalyst. The weight ratio, expressed as metal oxides, between the group VIB metal(s) to the group VIII metal(s) is preferably between 1.0 and 20, preferably between 2.0 and 10. For example, the hydrotreating reaction section of step b) of the method comprises a hydrotreating catalyst comprising 0.5% to 10% by weight of nickel, expressed as nickel oxide NiO, preferably 1% to 5% by weight of nickel relative to the total weight of the hydrotreating catalyst, and 1.0% to 30% by weight of molybdenum, expressed as molybdenum oxide MoO, preferably 3.0% to 20% by weight of molybdenum, relative to the total weight of the hydrotreating catalyst, on a mineral support.

[0042] The support for the at least one hydrotreating catalyst is advantageously selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof. The support may contain a dopant compound, in particular an oxide selected from the group consisting of boron oxide, especially boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide, and mixtures of these oxides. Preferably, the at least one hydrotreating catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron. If present, phosphorus pentoxide P2O5 has a concentration of less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. If present, boron trioxide B2O3 has a concentration of less than 10% by weight relative to the weight of the alumina and advantageously at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be γ (gamma) or η (eta) alumina.

[0043] The hydrotreating catalyst is, for example, in the form of extrudates.

[0044] Advantageously, the at least one hydrotreating catalyst used in step b) of the process has a specific surface area of 250 m 2 / g or more, preferably 300m 2 The specific surface area of the hydrotreating catalyst is advantageously 800 m 2 / g or less, preferably 600m 2 / g or less, especially 400m 2 / g or less. The specific surface area of the hydrotreating catalyst is measured by the BET method, i.e., the specific surface area is determined by nitrogen adsorption according to standard ASTM D 3663-78, which was established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938). Such a specific surface area allows for further improved removal of contaminants, in particular metals such as silicon.

[0045] Optionally, step b) may comprise a heating section, which is located upstream of the hydrotreating reaction section, in which the hydrotreated effluent obtained from step a) is heated to a temperature suitable for hydrotreating, i.e., a temperature between 250 and 370° C. Said optional heating section may therefore comprise one or more exchangers, preferably those allowing heat exchange between the hydrotreated effluent and the hydrotreated effluent, and / or a preheating furnace.

[0046] Advantageously, hydrotreating step b) allows complete hydrogenation of the olefins present in the initial feedstock and those that may be obtained after selective hydrogenation step a), but also allows at least partial conversion of other impurities present in the feedstock, such as aromatic compounds, metal compounds, sulfur compounds, nitrogen compounds, halogen compounds (especially chlorine compounds) and oxygen compounds. Step b) may also allow further reduction of the contaminant content, such as the metal content and in particular the silicon content.

[0047] (Separation step c)) According to the invention, the process comprises a separation step c), which is advantageously carried out in at least one washing / separation section, to which at least the hydrotreatment effluent obtained from step b) is fed, in order to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent.

[0048] The gaseous effluent advantageously comprises hydrogen, preferably essentially comprises hydrogen, i.e. at least 90% by volume, preferably at least 95% by volume, preferably at least 99% by volume of hydrogen. Advantageously, said gaseous effluent, preferably essentially containing hydrogen, may be at least partially recycled to the selective hydrogenation step a) and / or the hydrotreating step b), the recycling system optionally comprising a purification section. The aqueous effluent advantageously comprises ammonium salts and / or hydrochloric acid. The hydrocarbon effluent comprises hydrocarbon compounds and advantageously corresponds to the feedstock plastic pyrolysis oil or the plastic pyrolysis oil and a portion of a conventional petroleum-based feedstock co-processed with the pyrolysis oil, and is at least partially free from its impurities, in particular its olefinic impurities (diolefins and monoolefins), metallic impurities and halogenated impurities.

[0049] This separation step c) makes it possible in particular to remove ammonium chloride salts resulting from the reaction between chloride ions released by the hydrogenation of the chlorinated compounds during step b) and ammonium ions produced by the hydrogenation of the nitrogen-carrying compounds during step b) and / or provided by the injection of amines, and therefore to limit the risk of blockages, in particular blockages in the transfer lines and / or in the sections of the process according to the invention and / or in the transfer lines to the steam cracker, due to precipitation of ammonium chloride salts. It also makes it possible to remove hydrochloric acid formed by the reaction of hydrogen ions with chloride ions.

[0050] Depending on the content of chlorinated compounds in the initial feedstock to be treated, an amine stream 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 hydrotreating step b) and the separation step c), preferably upstream of the selective hydrogenation step a), to ensure a sufficient amount of ammonium ions to combine with the chloride ions formed during the hydrotreating step, thus making it possible to limit the formation of hydrochloric acid and therefore corrosion downstream of the separation section.

[0051] Advantageously, separation step c) comprises the injection of an aqueous solution into the hydrotreatment effluent obtained from step b), upstream of the washing / separation section, 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 blockages caused by the accumulation of ammonium chloride salts.

[0052] The separation step c) is advantageously carried out at temperatures between 50 and 370° C., preferentially between 100 and 340° C., preferably between 200 and 300° C. Advantageously, the separation step c) is carried out at a pressure close to that used in steps a) and / or b), facilitating the recycling of hydrogen.

[0053] The washing / separation section of step c) may be carried out at least in part in common or separate washing and separation equipment, which is well known (separation vessels, pumps, heat exchangers, wash columns, etc. which may be operated at various pressures and temperatures).

[0054] In this optional embodiment of the invention, which may be used in addition to or separately from the other described embodiments of the invention, separation step c) comprises the injection of an aqueous solution into the hydrotreatment effluent obtained from step b), followed by a scrubbing / separation section advantageously containing separate phases for obtaining at least one aqueous stream saturated with ammonium salts, a washed liquid hydrocarbon stream and a partially washed gaseous stream. The aqueous stream saturated with ammonium salts and the washed liquid hydrocarbon stream may then be separated in a decanting vessel to obtain said hydrocarbon effluent and said aqueous effluent. The partially washed gaseous stream may be introduced in parallel into a scrubbing column, where it flows countercurrently relative to an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrotreatment effluent, thereby making it possible to at least partially, preferably entirely, remove the hydrochloric acid contained in the partially washed gaseous stream and thus obtain said gaseous effluent, preferably essentially 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 may be used in a water recycle circuit for feeding step c) of separation into the aqueous solution and / or the aqueous stream in a wash column, optionally as a mixture with the acidic aqueous stream, upstream of the washing / separation section. The water recycle circuit may include a water supply and / or a purge to remove basic solution and / or dissolved salts.

[0055] In another optional embodiment of the invention, which may be utilized separately or in combination with the other described embodiments of the invention, separation step c) may advantageously comprise a "high pressure" washing / separation section, which operates at a pressure close to that of the selective hydrogenation step a) and / or the hydrotreating step b), facilitating the recycling of hydrogen. This "high pressure" section of step c) may be completed with a "low pressure" section, resulting in a hydrocarbon liquid fraction, free of the portion of gas dissolved at high pressure, which is intended to be directly processed in the steam cracking process and optionally sent to fractionation step d).

[0056] The hydrocarbon effluent obtained from separation step c) is sent directly to the inlet of the steam cracking unit or to an optional fractionation step d), preferably the hydrocarbon liquid effluent is sent to fractionation step d).

[0057] (Fractionation step d) (optional) The process according to the invention may, and preferably does, comprise a step of fractionating the hydrocarbon effluent to obtain at least one gaseous stream and at least two hydrocarbon streams having different boiling points. The fractionation step d) may, for example, make it possible to obtain a naphtha fraction having a boiling point below 150°C, in particular between 80 and 150°C, a hydrocarbon fraction having a boiling point above 150°C, or a naphtha fraction having a boiling point below 150°C, in particular between 80 and 150°C, a diesel fraction having a boiling point between 150°C and 385°C, and a hydrocarbon fraction having a boiling point above 385°C, which are referred to as heavy hydrocarbon fractions.

[0058] If present, step d) makes it possible in particular to remove gases dissolved in the hydrocarbon liquid effluent, such as ammonia, hydrogen sulfide and light hydrocarbons containing 1 to 4 carbon atoms, in particular under the action of the steam stream.

[0059] The pressure at which the optional fractionation step d) is carried out is advantageously less than 1.0 MPa (absolute), preferably between 0.1 and 1.0 MPa (absolute). Step d) can be carried out in a section comprising a stripping column, which is equipped with a reflux circuit comprising a reflux vessel. The stripping column is fed with the hydrocarbon liquid effluent obtained from step c) and a steam stream. The hydrocarbon liquid effluent obtained from step c) can optionally be heated before entering the stripping column. Thus, the lightest compounds are entrained at the top of the column and enter a reflux circuit comprising a reflux vessel, where gas / liquid separation takes place. The gas phase comprising light hydrocarbons is withdrawn from the reflux vessel as a gaseous stream. At least a portion of the liquid phase is advantageously withdrawn from the reflux vessel with a hydrocarbon stream having a relatively low boiling point, for example, a naphtha fraction having a boiling point below 150°C. The hydrocarbon stream is advantageously liquid and has a higher boiling point, for example greater than 150° C., than the hydrocarbon stream withdrawn at the top of the column, and is withdrawn at the bottom of the stripping column.

[0060] According to another embodiment, the fractionation step d) may comprise only a stripping column or a distillation column followed by a distillation column.

[0061] The hydrocarbon streams, for example, naphtha fractions with boiling points below 150° C. and fractions with boiling points above 150° C., may optionally be mixed and sent to a steam cracking unit, at the outlet of which olefins can be (re)formed and participate in the formation of polymers. Alternatively, naphtha streams, for example, those with boiling points below 150° C., may be sent to a naphtha pool, i.e., naphtha effluent, derived from more conventional petroleum-based feedstocks and generated in the same refinery in which the process according to the invention is carried out, and hydrocarbon streams with boiling points above 150° C. are sent for their part to a steam cracking unit. If the optional step d) results in obtaining a naphtha fraction (especially having a boiling point below 150°C), a diesel fraction (especially having a boiling point between 150°C and 385°C) and a heavy fraction (especially having a boiling point above 385°C), the naphtha fraction can be sent to a naphtha pool generated in the same refinery, and the diesel fraction can also be sent together with the heavy fraction to a steam cracking unit or to a diesel pool generated in the refinery.

[0062] According to one or more preferred embodiments of the present invention, separately or in combination, the method for treating a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the sequence of steps described above: pre-treatment step a0), selective hydrogenation step a), hydrotreating step b), separation step c) and optional fractionation step d), preferably in the given order, resulting in a treated plastic pyrolysis oil having a composition compatible with the input to the steam cracking unit.

[0063] The hydrocarbon effluent or, if the process according to the invention comprises a fractionation step, the hydrocarbon streams with different boiling points thus obtained by treating the plastic pyrolysis oil according to the process of the invention, have a composition that meets the specifications for the feedstock entering the steam cracking unit. In particular, the composition of the hydrocarbon effluent or of the hydrocarbon streams is preferably such that: - total content of metallic elements: not more than 5.0 ppm by weight, preferably not more than 2.0 ppm by weight, preferentially not more than 1.0 ppm by weight, preferably not more than 0.5 ppm by weight; - silicon element (Si) content: 1.0 ppm by weight or less, preferably 0.6 ppm by weight or less, and - Iron (Fe) content: 100 ppb or less by weight, sulfur content: not more than 500 ppm by weight, preferably not more than 200 ppm by weight; Nitrogen content: not more than 500 ppm by weight, preferably not more than 200 ppm by weight, - Asphaltene content: 5.0 ppm by weight or less, - Total content of chlorine atoms: 50 ppb by weight or less; - content of olefinic compounds (monoolefins and diolefins): less than or equal to 5.0% by weight, preferably less than or equal to 2.0% by weight, preferably less than or equal to 0.5% by weight;

[0064] The content is given as a relative weight concentration in weight percentage (%), parts by million (ppm) or parts by billion (ppb) relative to the total weight of the stream under consideration.

[0065] The method according to the invention therefore makes it possible to treat plastic pyrolysis oil to obtain an effluent that can be injected into a steam cracking unit. The method according to the invention therefore makes it possible to upgrade the plastic pyrolysis oil while simultaneously reducing the risk of coke formation and therefore blockage and / or premature loss of activity of the catalyst(s) used in the steam cracking unit, and reducing the risk of corrosion.

[0066] (Steam cracking step e) (optional) The hydrocarbon effluent obtained from the separation step c) or optionally at least one of the two hydrocarbon streams obtained from step d) may be sent to a steam cracking step e).

[0067] The steam cracking step e) is advantageously carried out in at least one pyrolysis furnace, the temperature of which is between 700 and 900°C, preferably between 750 and 850°C, and the pressure of which is between 0.05 and 0.3 MPa (relative). The residence time of the hydrocarbon compounds is generally less than 1.0 second (denoted as s), preferably between 0.1 and 0.5 seconds. Steam is advantageously introduced upstream of the optional steam cracking step e) and after separation (or fractionation). The amount of water introduced, advantageously in the form of steam, is between 0.3 and 3.0 kg of water per kg of hydrocarbon compounds by weight entering step e). Optional step e) is preferably carried out in several parallel pyrolysis furnaces, the operating conditions being adapted to the various streams feeding step e) and to manage the decoding time of the tubes. The furnace may comprise one or several tubes arranged in parallel. The furnace may also refer to a group of furnaces operating in parallel. For example, one furnace may be dedicated to cracking hydrocarbon streams containing compounds with boiling points below 150°C, particularly between 80 and 150°C, and another furnace may be dedicated to cracking hydrocarbon streams containing compounds with boiling points above 150°C.

[0068] This steam cracking step e) makes it possible to obtain at least one effluent, in particular one effluent per hydrocarbon stream sent to steam cracking step e), containing a satisfactory content of olefins containing 2, 3 and / or 4 carbon atoms (i.e. C2, C3 and / or C4 olefins), in particular a content of 30% by weight or more, in particular 40% by weight or more, or even 50% by weight or more of all olefins containing 2, 3 and 4 carbon atoms, relative to the weight of the steam cracking effluent under consideration. The C2, C3 and C4 olefins can advantageously be used as polyolefin monomers.

[0069] According to one or more preferred embodiments of the present invention, to be utilized separately or in combination, the method for processing a feedstock comprising plastic pyrolysis oil comprises, and preferably consists of, the sequence of steps described above, namely, a pretreatment step a0), a selective hydrogenation step a), a hydrotreatment step b), a separation step c), an optional fractionation step d), and a steam cracking step e), preferably in the given order.

[0070] The process according to the invention, if it comprises this steam cracking step e), therefore makes it possible to obtain from plastic pyrolysis oils, e.g. plastic waste, olefins which can serve as monomers for the synthesis of new polymers in relatively satisfactory yields without blockage or corrosion of the unit.

[0071] The following figures and examples illustrate the present invention but do not limit its scope.

[0072] (Analysis methods used) The analytical methods and / or criteria used to determine the characteristics of the various streams, in particular the feed and effluent streams to be treated, are known to those skilled in the art and are in particular listed below.

[0073] [Table 1]

[0074] (List of drawings) The information regarding the elements referenced in Figures 1-3 allows for a better understanding of the invention, but the invention is not limited to the specific embodiments illustrated in Figures 1-3. The various embodiments presented may be used alone or in combination with each other, and there are no limitations on combinations.

[0075] FIG. 1 shows a scheme of one embodiment of the method of the present invention, which includes: - step a) of selective hydrogenation of a hydrocarbon feedstock (1) obtained from the thermal decomposition of plastics; carried out in at least one fixed-bed reactor containing at least one selective hydrogenation catalyst in the presence of a hydrogen-rich gas (2) and optionally an amine provided by a stream (3), to obtain an effluent (4); - step b) of hydrotreating the effluent (4) obtained from step a) in the presence of hydrogen (5) in at least one fixed-bed reactor containing at least one hydrotreating catalyst to obtain a hydrotreated effluent (6); - step c) of separation of the effluent (6); carried out in the presence of an aqueous wash solution (7), making it possible to obtain at least one fraction (8) containing hydrogen, an aqueous fraction (9) containing dissolved salts, and a hydrocarbon liquid fraction (10).

[0076] Instead of injecting the amine stream (3) at the inlet of the selective hydrogenation step a), it is possible, depending on the characteristics of the feedstock, to inject it at the inlet of the hydrotreating step b), at the inlet of the separation step c), or else not to inject it.

[0077] Figure 2 shows a variant of the implementation of the process according to the invention shown in Figure 1. In the embodiment shown in Figure 2, the hydrocarbon liquid fraction (10) obtained at the end of step c) is sent to a fractionation step d) making it possible to obtain at least one gaseous fraction (11), a naphtha-containing fraction (12) and a hydrocarbon fraction (13).

[0078] Figure 3 shows a variant of the implementation of the process according to the invention shown in Figure 2. In the embodiment shown in Figure 3, a hydrocarbon feedstock (1) obtained from the pyrolysis of plastics undergoes a pretreatment step a0) prior to the selective hydrogenation step a). The pretreated feedstock (14) is fed to the selective hydrogenation step a).

[0079] Only the main steps, together with the main flows, are shown in Figures 1 to 3 to allow a better understanding of the invention. It is clearly understood that all the equipment required for the functioning (vessels, pumps, exchangers, furnaces, columns, etc.) is present, even if not shown. It is also understood that the above-mentioned hydrogen-rich gaseous stream (feed or recycle) may be injected at the inlet of each reactor or catalyst bed or between two reactors or two catalyst beds. Means known to those skilled in the art may be used to purify and recycle hydrogen.

[0080] At the end of step d), the naphtha-containing fraction (12) and / or the hydrocarbon fraction (13) are sent to a steam cracking process.

[0081] (Example) Example 1 (according to the present invention) The feedstock treated in this method is plastic pyrolysis oil (i.e., containing 100% by weight of said plastic pyrolysis oil) and has the characteristics indicated in Table 2.

[0082] [Table 2]

[0083] (1) The MAV method is described in the paper: C. Lopez-Garcia et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68.

[0084] The feedstock (1) is subjected to a selective hydrogenation step a), which is carried out in a fixed-bed reactor in the presence of hydrogen (2) and an alumina-supported NiMo type selective hydrogenation catalyst under the conditions indicated in Table 3.

[0085] [Table 3]

[0086] At the end of the selective hydrogenation step a), all of the diolefins originally present in the feedstock have been converted.

[0087] The effluent (4) obtained from the selective hydrogenation step a) is subjected directly, without separation, to a hydrotreating step b), which is carried out in a fixed bed in the presence of hydrogen (5) and an alumina-supported NiMo type hydrotreating catalyst under the conditions set out in Table 4.

[0088] [Table 4]

[0089] The effluent (6) obtained from the hydrotreating step b) is subjected to a separation step c): a water stream is injected into the effluent obtained from the hydrotreating step b); the mixture is then treated in an acid gas washing tower and a separation vessel. The liquid effluent obtained is then sent to a fractionation step d), which comprises a stripping tower. The yields of the various fractions obtained after separation and fractionation are indicated in Table 5 (the yields correspond to the ratio of the mass of the various products obtained relative to the mass of the feedstock upstream of step a), expressed as a percentage (%) and denoted as %m / m).

[0090] [Table 5]

[0091] The characteristics of the PI-150°C and 150°C+ liquid fractions (and also the PI+ fraction being the sum of the PI-150°C and 150°C+ fractions) obtained after separation step c) and fractionation step are presented in Table 6.

[0092] [Table 6]

[0093] Both liquid fractions PI-150°C and 150°C+ have compositions that are compatible with steam cracking units for the following reasons: - they do not contain any olefins (monoolefins and diolefins); - they have very low contents of elemental chlorine (undetectable and 25 ppb by weight, respectively), which are below the limit required for steam cracking feedstocks (≦50 ppb by weight); - the content of metals, especially iron (Fe), is also very low (the content of metals is not detected for the PI-150°C fraction and <1 ppm by weight for the 150°C+ fraction; the content of Fe is not detected for the PI-150°C fraction and 50 ppb by weight for the 150°C+ fraction), which is below the limits required for steam cracking feedstocks (≦5.0 ppm by weight for metals, very preferably ≦1 ppm by weight; ≦100 ppb by weight for Fe); Finally, they contain sulfur (<2 ppm by weight for the PI-150°C fraction and <10 ppm by weight for the 150°C+ fraction) and nitrogen (<0.5 ppm by weight for the PI-150°C fraction and <5 ppb by weight for the 150°C+ fraction) in contents that are significantly lower than the limits required for steam cracking feedstocks (≦500 ppm by weight, preferably ≦200 ppm by weight for S and N).

[0094] The mixture of the two liquid fractions, designated PI+, also appears to have a very low content of olefins and contaminants (particularly metals, chlorine, sulfur, and nitrogen) making the composition suitable for steam cracking units.

[0095] The resulting liquid fractions PI-150°C and 150°C+ are therefore sent to a steam cracking step, where they are cracked under various conditions (see Table 7). The PI+ mixture can also be sent directly to a steam cracking step under the conditions mentioned in Table 7.

[0096] [Table 7]

[0097] The effluents from the various steam crackers are subjected to a separation step which allows the recycling of saturated compounds to the steam cracker, and the production yields are presented in Table 8 (yield = % by mass of product relative to the respective mass of the fraction upstream of the steam cracking step, expressed as %m / m).

[0098] [Table 8]

[0099] By considering the yields obtained for the various liquid fractions PI-150°C and 150°C+ (and their PI+ mixtures) during the pyrolysis oil treatment process (see Table 5), it is possible to determine the overall yield for the products obtained from the steam cracking step relative to the initial feedstock of plastic pyrolysis oil type introduced in step a).

[0100] [Table 9]

[0101] When the liquid fraction PI+ is subjected to a steam cracking step, the method according to the invention makes it possible to achieve overall mass yields of ethylene and propylene of 34.7% and 18.9%, respectively, relative to the amount of mass of the initial feedstock of the plastic pyrolysis oil type. When the PI-150°C and 150°C+ fractions are sent separately to a steam cracking unit, the method according to the invention makes it possible to achieve overall mass yields of ethylene and propylene of 33.9% (=9.5+24.4) and 18.5% (=5.2+13.3), respectively, relative to the amount of mass of the initial feedstock of the plastic pyrolysis oil type.

[0102] Furthermore, a particular sequence of steps upstream of the steam cracking step makes it possible to limit coke formation and avoid corrosion problems that would otherwise appear from having unremoved chlorine.

[0103] Example 2 (according to the present invention) In this embodiment, the fractionation process includes a distillation section in addition to the stripping column to obtain a diesel fraction that can be directly integrated into the diesel pool, i.e., it meets the specifications required for diesel, in particular the T90 D86 specification at 360°C.

[0104] The feedstock to be treated is the same as that described in Example 1 (see Table 2).

[0105] It undergoes a step a) of selective hydrogenation, a step b) of hydrotreating and a step c) of separation. These steps are carried out under the same conditions as those described in Example 1. The liquid effluent obtained at the end of separation step c) is sent to a stripping column, as in Example 1. At the end of the stripping column, two fractions PI-150°C and 150°C+ are obtained, as in Example 1, which have the same characteristics as those of Example 1 (see Table 6). The 150°C+ fraction is sent to a distillation column, where it is distilled into two fractions: a 150-385°C fraction and a 385°C+ fraction. Table 10 gives the overall yields for the various fractions obtained at the end of separation step c) and fractionation step d) (these include the stripping column and the distillation column).

[0106] [Table 10]

[0107] Table 11 gives the characteristics of the 150-385°C and 385°C+ fractions and the EN-590 commercial specifications for diesel.

[0108] [Table 11]

[0109] Table 11 shows that the 150-385°C fraction has the required quality to be sent directly to the diesel pool.

[0110] Example 3 (not in accordance with the present invention) In this example, the same pyrolysis oil type hydrocarbon feedstock as used in Example 1 is sent directly to a steam cracking step.

[0111] The yields by mass of the different products obtained are calculated relative to the initial feedstock (see Table 12).

[0112] [Table 12]

[0113] The ethylene and propylene yields obtained after direct steam cracking of the pyrolysis oil (a process not in accordance with the invention) and presented in Table 12 are lower than the yields obtained after steam cracking of the feedstock obtained from the treatment by the process of the invention of the same plastic pyrolysis oil of Example 1 (see Table 8), demonstrating the advantages of the process according to the invention. Furthermore, the treatment of the pyrolysis oil directly in a steam cracking furnace (Example 2) resulted in increased coke formation, which required premature shutdown of the furnace. [Brief explanation of the drawings]

[0114] [Figure 1] 1 shows a scheme of one embodiment of the method of the present invention. [Figure 2] 2 is a variant of the implementation of the method according to the invention shown in FIG. 1; [Figure 3] 3 is a variant of the implementation of the method according to the invention shown in FIG. 2;

Claims

1. 1. A method for treating a feedstock containing plastic pyrolysis oil, said plastic pyrolysis oil containing monoolefins and / or diolefins, metal and halogenated compounds, comprising at least the following steps: a) a selective hydrogenation step carried out in the presence of at least one selective hydrogenation catalyst in a reaction section, to which the feedstock and a gaseous stream containing hydrogen are fed, the feedstock being maintained in a liquid phase, the temperature during the step being 100 to 250°C, the partial pressure of hydrogen being 1.0 to 10.0 MPa (absolute), and the hourly space velocity being 1.0 to 10.0 h －１ and the amount of gaseous stream fed to said reaction section is such that the hydrogen coverage is 1-50 Nm 3 of hydrogen per volume (m 3 ) of feedstock to obtain a hydrogenated effluent; b) a hydrotreating step carried out in a hydrotreating reaction section comprising a fixed bed reactor containing n catalyst beds, n being an integer equal to or greater than 1, wherein when n is 1, it contains at least one hydrotreating catalyst, and when n is a plurality of catalyst beds, they are arranged in series and each contains at least one hydrotreating catalyst, and the hydrotreating effluent from step a) and a gaseous stream containing hydrogen are fed to the first catalyst bed of the hydrotreating reaction section at a temperature of 250 to 430°C, a hydrogen partial pressure of 1.0 to 10.0 MPa (absolute), and an hourly space velocity of 0.1 to 10.0 h －１ to obtain a hydrotreated effluent; c) a separation step carried out in at least one washing / separation section, to which the hydrotreated effluent obtained from step b) and water are fed and which is carried out at a temperature of 50 to 370°C, in order to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon effluent, said step c) comprising the injection of water into the hydrotreated effluent obtained from step b) upstream of the washing / separation section; A method comprising:

2. a step a) of pre-treating a feedstock containing plastic pyrolysis oil; ０ ), wherein the pretreatment step, preceding the selective hydrogenation step a), is carried out in an adsorption section to which the feedstock is fed and which is operated at a temperature of 0 to 150°C and a pressure of 0.15 to 10.0 MPa (absolute) in the presence of at least one adsorbent, the adsorbent having a specific surface area of 100 m ２ 10. The method of claim 1, wherein the pre-treated feedstock has a % saturation of 0.15 to 0.25 g / g or more and is fed to the section of step a).

3. 3. The method according to claim 1, wherein the temperature at which the selective hydrogenation step a) is carried out is 110 to 200°C in step a).

4. 4. The process according to claim 1, wherein the reaction section of step a) employs at least two reactors operating in a configuration-variable system.

5. 5. The method according to claim 1, wherein the at least one selective hydrogenation catalyst comprises a support and at least one Group VIII element and / or at least one Group VIB element, wherein the support is selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, the Group VIII element is selected from the group consisting of nickel and cobalt, and the Group VIB element is selected from the group consisting of molybdenum and tungsten.

6. The at least one selective hydrogenation catalyst contains less than 1% by weight of nickel, expressed as nickel oxide, NiO, relative to the weight of the catalyst, and at least 0.1% by weight of molybdenum oxide, MoO, relative to the weight of the catalyst. ３ 6. The method of claim 5, comprising less than 5 wt. % and a minimum of 0.1 wt. % molybdenum, expressed as a molybdenum content of 0.1 wt. % on an alumina support.

7. 7. The process according to claim 1, wherein an additional gaseous stream comprising hydrogen is introduced from a second catalyst bed at the inlet of each catalyst bed in the hydrotreating reaction section of step b).

8. The amount of gaseous stream fed to the hydrotreating reaction section of step b) is determined so that the hydrogen coverage is greater than the volume (m ) of the hydrogenated effluent obtained from step a). ３ 8. The method according to claim 1, wherein the amount of hydrogen per 1000 kcal / kg of the mixture is 50 to 500 Nm 3 of hydrogen per 1000 kcal / kg of the mixture.

9. 9. The method according to any one of claims 1 to 8, wherein the at least one hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and contains 0.5% to 10% by weight of nickel, expressed as nickel oxide NiO relative to the total weight of the hydrotreating catalyst, and 1.0% to 30% by weight of molybdenum, expressed as molybdenum oxide MoO 3 relative to the total weight of the hydrotreating catalyst.

10. The at least one hydrotreating catalyst has a specific surface area of 250 m ２ The method according to any one of claims 1 to 9, wherein the saturation coefficient is 1 / g or more.

11. The method of any one of claims 1 to 10, further comprising a fractionation step d) subsequent to step c).

12. The method according to any one of claims 1 to 11, further comprising a steam cracking step e) following step d), which is carried out in at least one pyrolysis furnace at a temperature of 700 to 900°C and a pressure of 0.05 to 0.3 MPa (relative).

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