US20250313765A1 - Method for treating plastic pyrolysis oil including an h2s recycling step - Google Patents

Method for treating plastic pyrolysis oil including an h2s recycling step

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US20250313765A1
US20250313765A1 US18/860,831 US202318860831A US2025313765A1 US 20250313765 A1 US20250313765 A1 US 20250313765A1 US 202318860831 A US202318860831 A US 202318860831A US 2025313765 A1 US2025313765 A1 US 2025313765A1
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stage
effluent
weight
resulting
separation
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Inventor
Jerome Bonnardot
Loïk GUENAULT
Floriane MALDONADO
Inigo RIBAS SANGUESA
Martin SANTOS MARTINEZ
Sheyla CARRASCO HERNANDEZ
Wilfried Weiss
Marisa DE SOUSA DUARTE
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Repsol SA
IFP Energies Nouvelles IFPEN
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Repsol SA
IFP Energies Nouvelles IFPEN
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Assigned to REPSOL S.A., IFP Energies Nouvelles reassignment REPSOL S.A. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CARRASCO HERNANDEZ, Sheyla, RIBAS SANGUESA, INIGO, SANTOS MARTINEZ, Martin, BONNARDOT, JEROME, GUENAULT, Loïk, WEISS, WILFRIED, DE SOUSA DUARTE, Marisa
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/002—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal in combination with oil conversion- or refining processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/10—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal from rubber or rubber waste
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G47/00—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G49/00—Treatment of hydrocarbon oils, in the presence of hydrogen or hydrogen-generating compounds, not provided for in a single one of groups C10G45/02, C10G45/32, C10G45/44, C10G45/58 or C10G47/00
    • C10G49/22—Separation of effluents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
    • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
    • C10G65/04—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including only refining steps
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
    • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
    • C10G65/12—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including cracking steps and other hydrotreatment steps
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
    • C10B53/07—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form of solid raw materials consisting of synthetic polymeric materials, e.g. tyres
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1003—Waste materials
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/20—Characteristics of the feedstock or the products
    • C10G2300/201—Impurities
    • C10G2300/207—Acid gases, e.g. H2S, COS, SO2, HCN
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/40—Characteristics of the process deviating from typical ways of processing
    • C10G2300/4006—Temperature
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/40—Characteristics of the process deviating from typical ways of processing
    • C10G2300/4012—Pressure
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/70—Catalyst aspects

Definitions

  • the present invention relates to a process for the treatment of a plastics pyrolysis oil in order to obtain a hydrocarbon effluent which can be upgraded in a unit for the storage of petrol, jet or gas-oil fuels or as feedstock of a steam cracking unit. More particularly, the present invention relates to a process for the treatment of a feedstock resulting from the pyrolysis of plastic waste making it possible to recycle a gas phase containing H 2 S resulting from the process in order to keep the catalysts in sulfide form in the catalytic stages of the process and thus to reduce the consumption of sulfiding agent to be added.
  • Plastics resulting from collection and sorting channels can undergo a stage of pyrolysis in order to obtain, inter alia, pyrolysis oils. These plastics pyrolysis oils are generally incinerated in order to generate electricity and/or used as fuel in industrial or urban heating boilers.
  • plastic waste is generally a mixture of several polymers, for example mixtures of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride or polystyrene.
  • the plastics may contain, in addition to polymers, other compounds, such as plasticizers, pigments, dyes or also residues of polymerization catalysts.
  • Plastic waste may additionally contain, in a minor amount, biomass originating, for example, from household waste.
  • the treatment of waste can also cause corrosion.
  • the oils resulting from the pyrolysis of plastic waste comprise a lot of impurities, in particular diolefins, metals, in particular iron, silicon, or also halogen compounds, in particular chlorine-based compounds, heteroelements, such as sulfur, oxygen and nitrogen, and insoluble materials, at contents which are often high and incompatible with steam cracking units or units located downstream of steam cracking units, in particular polymerization processes and selective hydrogenation processes.
  • the yields of light olefins sought for the petrochemical industry, in particular ethylene and propylene, are strongly dependent on the quality of the feedstocks sent for steam cracking.
  • the BMCI Boau of Mines Correlation Index
  • This index developed for hydrocarbon products resulting from crude oils, is calculated from the measurement of the density and the average boiling point: it is equal to 0 for a linear paraffin and to 100 for benzene. Its value thus increases in proportion as the product analysed has a condensed aromatic structure, naphthenes having a BMCI intermediate between paraffins and aromatics.
  • the yields of light olefins increase when the paraffin content increases and thus when the BMCI decreases.
  • the yields of undesired heavy compounds and/or of coke increase when the BMCI increases.
  • the document WO 2018/055555 provides an overall process for the recycling of plastic waste, which is very general and relatively complex, ranging from the very stage of pyrolysis of the plastic waste up to the steam cracking stage.
  • the process of the application WO 2018/055555 comprises, inter alia, a stage of hydrotreating the liquid phase resulting directly from the pyrolysis, preferably under quite stringent conditions, in particular in terms of temperature, for example at a temperature of between 260 and 300° C., a stage of separation of the hydrotreating effluent and then a stage of hydrodealkylation of the separated heavy effluent at a preferably high temperature, for example of between 260 and 400° C.
  • the unpublished patent application FR 21/00.026 describes a process for the treatment of a plastics pyrolysis oil targeted at reducing and/or at removing the impurities contained in the pyrolysis oil in order to obtain an effluent compatible for a steam cracker.
  • the process comprises the following stages:
  • One route for removing the impurities contained in the ex-plastics pyrolysis oils is thus to carry out a hydrotreating in the presence of catalysts which are active in sulfide form.
  • the feedstocks available are generally fairly poor in sulfur.
  • a minimum pH 2 Sp is necessary in the hydrotreating reactor in order to keep the catalysts in sulfide form and thus not to reduce them.
  • a sulfiding agent is generally, indeed even necessarily, continuously added, typically DMDS (dimethyl disulfide), to the feedstock.
  • DMDS dimethyl disulfide
  • H 2 S contained in the effluent forms ammonium sulfide salts ((NH 4 ) 2 S) with the NH 3 generated by the hydrogenation of nitrogen compounds during the hydrotreating.
  • ex-plastics pyrolysis oils generally contain greater contents of nitrogen than contents of sulfur.
  • These salts are generally removed by scrubbing with water, followed by a (single) stage of steam stripping of the aqueous effluent, making it possible to obtain a purified aqueous effluent and a gas phase containing H 2 S and NH 3 , which are generally discharged together at the top of the stripping column.
  • the gas phase containing H 2 S and NH 3 is subsequently generally incinerated to form SO x (sulfur oxides) and N 2 or NO x (nitrogen oxides).
  • the gas phase containing H 2 S and NH 3 might be recovered and returned to the inlet of the hydrotreating unit in order to maintain the pH 2 Sp in the reactor without adding a sulfiding agent.
  • the NH 3 contained in this gas phase prevents this from being done as there would be a concentration of NH 3 in the recycling loop which would be prejudicial to the operation of the unit.
  • the presence of NH 3 lowers the pH 2 p.
  • the gas phase containing H 2 S and NH 3 thus cannot be reused directly as source of H 2 S for keeping the catalysts in sulfide form.
  • the invention relates to a process for the treatment of a feedstock comprising a plastics pyrolysis oil, comprising:
  • the present invention thus relates to a process making it possible to purify an oil resulting from the pyrolysis of plastic waste of at least a part of its impurities, which makes it possible to hydrogenate it and thus to be able to upgrade it in particular by incorporating it directly in the fuel storage unit or else by rendering it compatible with a treatment in a steam cracking unit while being able to recycle the H 2 S resulting from the process continuously in order to minimize the consumption of sulfiding agent.
  • the injection of a sulfiding agent remains in particular necessary at the start of the catalytic cycle, the time that the H 2 S is formed in order to be separated in stage d) and recycled upstream of stage a) and/or of stage b) and/or of stage g), and/or also upstream of the selective hydrogenation stage a0). Additional injections throughout the catalytic cycle may be necessary in order to compensate for the natural loss.
  • the fact of being able to recycle a gas phase containing the H 2 S without the NH 3 by the present invention makes it possible to considerably reduce the consumption of the sulfiding agent.
  • Another advantage is the removal of the NH 3 in the gaseous effluent comprising hydrogen and/or light hydrocarbons from the top of the separation/scrubbing section (stage c)) by reaction with the recycled excess H 2 S in the form of ammonium sulfide in the aqueous effluent.
  • the NH 3 leaves in the form of salt in the aqueous effluent.
  • Another advantage of the invention is that of preventing risks of plugging and/or of corrosion of the treatment unit in which the process of the invention is carried out, the risks being exacerbated by the presence, often in large amounts, of diolefins, metals and halogen compounds in the plastics pyrolysis oil.
  • the process of the invention thus makes it possible to obtain a hydrocarbon effluent, resulting from a plastics pyrolysis oil, which is freed, at least partly, of the impurities of the starting plastics pyrolysis oil, thus limiting the problems of operability, such as the corrosion, coking or catalytic deactivation problems, which may be brought about by these impurities, in particular in steam cracking units and/or in units located downstream of the steam cracking units, in particular the polymerization and hydrogenation units.
  • the removal of at least a part of the impurities of the oils resulting from the pyrolysis of plastic waste will also make it possible to increase the range of applications of the target polymers, the incompatibilities of usages being reduced.
  • the process comprises the hydrogenation stage a).
  • the process comprises the fractionation stage f).
  • the process comprises the hydrocracking stage g).
  • the separation stage c) comprises the following stages:
  • the process comprises at least one stage a0) of pretreatment of the feedstock comprising a plastics pyrolysis oil, optionally as a mixture with the hydrocarbon effluent resulting from stage c), said pretreatment stage being carried out upstream of stage a) and/or upstream of stage b), and comprises a filtration stage and/or a centrifugation stage and/or an electrostatic separation stage and/or a stage of scrubbing by means of an aqueous solution and/or an adsorption stage and/or a selective hydrogenation stage.
  • the hydrocarbon effluent resulting from the separation stage c), or at least one of the two liquid hydrocarbon cuts resulting from stage f), is sent, completely or partly, to a steam cracking stage h) carried out in at least one pyrolysis furnace at a temperature of between 700 and 900° C. and at a pressure of between 0.05 and 0.3 MPa relative.
  • said hydrogenation catalyst comprises a support chosen from alumina, silica, silicas-aluminas, magnesia, clays and their mixtures and a hydro-dehydrogenating function comprising either at least one element from group VIII and at least one element from group VIB, or at least one element from group VIII.
  • said hydrotreating catalyst comprises a support chosen from the group consisting of alumina, silica, silicas-aluminas, magnesia, clays and their mixtures and a hydro-dehydrogenating function comprising at least one element from group VIII and/or at least one element from group VIB.
  • the process additionally comprises a second hydrocracking stage g′) carried out in a hydrocracking reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a part of the first hydrocracked effluent resulting from the first hydrocracking stage g) and a gas stream comprising hydrogen, said hydrocracking reaction section being employed at a temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁇ 1 , in order to obtain a second hydrocracked effluent.
  • a second hydrocracking stage g′ carried out in a hydrocracking reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at
  • the invention also relates to the product liable to be obtained, and preferably obtained, by the process according to the invention.
  • the pressures are absolute pressures, also denoted abs., and are given in MPa absolute (or MPa abs.), unless otherwise indicated.
  • the expressions “of between . . . and . . . ” and “between . . . and . . . ” are equivalent and mean that the limiting values of the interval are included in the described range of values. If such were not the case and if the limiting values were not included in the described range, such a piece of information will be revealed by the present invention.
  • the various parameter ranges for a given stage can be used alone or in combination.
  • a range of preferred pressure values can be combined with a range of more preferred temperature values.
  • group VIII (or VIIIB) according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.
  • the content of metals is measured by X-ray fluorescence.
  • a “plastics pyrolysis oil” is an oil, advantageously in liquid form at ambient temperature, resulting from the pyrolysis of plastics, preferably of plastic waste originating in particular from collection and sorting channels. It can also result from the pyrolysis of worn tyres.
  • hydrocarbon compounds especially paraffins, mono- and/or diolefins, naphthenes and aromatics. At least 80% by weight of these hydrocarbon compounds preferably have a boiling point of less than 700° C. and preferably of less than 550° C.
  • the latter can comprise up to 70% by weight of paraffins, up to 90% by weight of olefins and up to 90% by weight of aromatics, it being understood that the sum of the paraffins, of the olefins and of the aromatics is 100% by weight of the hydrocarbon compounds.
  • the density of the pyrolysis oil measured at 15° C. according to the ASTM D4052 method, is generally of between 0.75 and 0.99 g/cm 3 , preferably of between 0.75 and 0.95 g/cm 3 .
  • the plastics pyrolysis oil can additionally comprise, and usually does comprise, impurities such as metals, in particular iron, silicon or halogen compounds, in particular chlorine compounds. These impurities can be present in the plastics pyrolysis oil at high contents, for example up to 350 ppm by weight or also 700 ppm by weight, indeed even 1000 ppm by weight, of halogen elements (in particular chlorine) contributed by halogen compounds, and up to 100 ppm by weight, indeed even 200 ppm by weight, of metal or semi-metal elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals and metalloids can be put into the same category as contaminants of metal nature, referred to as metals or metal or semi-metal elements.
  • impurities such as metals, in particular iron, silicon or halogen compounds, in particular chlorine compounds.
  • the metals or metal or semi-metal elements possibly contained in the oils resulting from the pyrolysis of plastic waste comprise silicon, iron or both these elements.
  • the plastics pyrolysis oil can also comprise other impurities, such as heteroelements contributed in particular by sulfur compounds, oxygen compounds and/or nitrogen compounds, at contents generally of less than 27 000 ppm by weight of heteroelements and preferably of less than 15 500 ppm by weight of heteroelements.
  • the sulfur compounds are generally present in a content of less than 2000 ppm by weight and preferably of less than 500 ppm by weight.
  • the oxygen compounds are generally present in a content of less than 15 000 ppm by weight and preferably of less than 10 000 ppm by weight.
  • the nitrogen compounds are generally present in a content of less than 10 000 ppm by weight and preferably of less than 5000 ppm by weight.
  • the plastics pyrolysis oil can also comprise other impurities, such as heavy metals, for example mercury, arsenic, zinc and lead, for example up to 100 ppb by weight or also 200 ppb by weight of mercury.
  • the feedstock of the process according to the invention comprises at least one plastics pyrolysis oil.
  • Said feedstock can consist solely of plastics pyrolysis oil(s).
  • said feedstock comprises at least 50% by weight, preferably between 70% and 100% by weight, of plastics pyrolysis oil, with respect to the total weight of the feedstock, that is to say preferably between 50% and 100% by weight and in a preferred way between 70% and 100% by weight of plastics pyrolysis oil.
  • the conventional petroleum feedstock can advantageously be a cut or a mixture of cuts of naphtha, gas oil or vacuum gas oil type.
  • Frying oils various animal oils, such as fish oils, tallow or lard, can also be used.
  • the feedstock resulting from the conversion of biomass can also advantageously be chosen from methyl esters of fatty acids of vegetable and/or animal origin or also methyl esters of fatty acids of waste food vegetable oils.
  • the feedstock resulting from the conversion of biomass can also be chosen from feedstocks originating from processes for thermal or catalytic conversions of biomass, such as oils which are produced from biomass, in particular from lignocellulosic biomass, with various liquefaction methods, such as hydrothermal liquefaction or pyrolysis.
  • biomass refers to a material derived from recently living organisms, which comprises plants, animals and their by-products.
  • lignocellulosic biomass denotes biomass derived from plants or from their by-products.
  • the lignocellulosic biomass is composed of carbohydrate polymers (cellulose, hemicellulose) and of an aromatic polymer (lignin).
  • the feedstock resulting from the conversion of biomass can also advantageously be chosen from feedstocks resulting from the papermaking industry.
  • the plastics pyrolysis oil can result from a thermal or catalytic pyrolysis treatment or also be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and of hydrogen).
  • Said feedstock comprising a plastics pyrolysis oil, optionally as a mixture with the hydrocarbon effluent from stage c), can advantageously be pretreated in at least one optional pretreatment stage a0), prior to the hydrogenation stage a) and/or the hydrotreating stage b), in order to obtain a pretreated feedstock which feeds stage a) and/or stage b).
  • this optional pretreatment stage a0 makes it possible to reduce the amount of contaminants and of solid particles, in particular the amount of iron and/or of silicon and/or of chlorine, possibly present in the feedstock comprising a plastics pyrolysis oil.
  • This optional stage a0) makes possible in particular the removal of sediments which can be formed as a result of the unstable nature of the pyrolysis oils and/or of a problem of compatibility between two different feedstocks.
  • an optional stage a0) of pretreatment of the feedstock comprising a plastics pyrolysis oil is advantageously carried out, especially when said feedstock comprises more than 10 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 50 ppm by weight, of metal elements and/or of solid particles, and especially when said feedstock comprises more than 5 ppm by weight of silicon, more particularly more than 10 ppm by weight, indeed even more than 20 ppm by weight, of silicon.
  • an optional stage a0) of pretreatment of the feedstock comprising a plastics pyrolysis oil is advantageously carried out especially when said feedstock comprises more than 10 ppm by weight, in particular more than 20 ppm by weight, more particularly more than 50 ppm by weight, of chlorine.
  • Said optional pretreatment stage a0 can be carried out by any method known to a person skilled in the art which makes it possible to reduce the amount of contaminants. It can in particular comprise a filtration stage and/or a centrifugation stage and/or an electrostatic separation stage and/or a stage of scrubbing by means of an aqueous solution and/or an adsorption stage and/or a selective hydrogenation stage.
  • the optional pretreatment stage a0 comprises a filtration stage and/or a centrifugation stage and/or an electrostatic separation stage and/or a stage of scrubbing by means of an aqueous solution and/or an adsorption stage
  • a temperature between 20 and 400° C., preferably between 40 and 350° C.
  • a pressure between 0.15 and 10.0 MPa abs., preferably between 0.2 and 7.0 MPa abs.
  • said optional pretreatment stage a0) is carried out in an adsorption section operated in the presence of at least one adsorbent, preferably of alumina type, having a specific surface of greater than or equal to 100 m 2 /g, preferably of greater than or equal to 200 m 2 /g.
  • the specific surface of said at least one adsorbent is advantageously less than or equal to 600 m 2 /g, in particular less than or equal to 400 m 2 /g.
  • said adsorbent comprises less than 1% by weight of metal elements and is preferably devoid of metal elements.
  • metal elements of the adsorbent should be understood as meaning the elements of Columns 6 to 10 of the Periodic Table of the Elements (new IUPAC classification).
  • the residence time of the feedstock in the adsorption section is generally of between 1 and 180 minutes.
  • Said adsorption section of the optional stage a0) comprises at least one adsorption column, preferably comprises at least two adsorption columns, preferentially between two and four adsorption columns, containing said adsorbent.
  • one operating mode can be a “swing” operation, in which one of the columns is on-line, that is to say in operation, while the other column is in reserve.
  • the adsorbent of the on-line column is spent, this column is isolated, while the column in reserve is placed on-line, i.e. in operation.
  • the spent adsorbent can subsequently be regenerated in situ and/or replaced with fresh adsorbent so that the column containing it can again be brought back on-line once the other column has been isolated.
  • Another operating mode is to have at least two columns operating in series.
  • the adsorbent of the column placed at the head is spent, this first column is isolated and the spent adsorbent is either regenerated in situ or replaced with fresh adsorbent.
  • the column is subsequently brought back on-line in the last position, and so on.
  • This operation is known as permutable mode, or according to the term PRS for Permutable Reactor System, or also “lead and lag”.
  • the combination of at least two adsorption columns makes it possible to overcome the possible and potentially rapid poisoning and/or clogging of the adsorbent due to the combined action of the metal contaminants, of the diolefins, of the gums resulting from the diolefins and of the insoluble matter which may be present in the plastics pyrolysis oil to be treated.
  • the reason for this is that the presence of at least two adsorption columns facilitates the replacement and/or the regeneration of the adsorbent, advantageously without shutdown of the pretreatment unit, indeed even of the process, thus making it possible to reduce the risks of clogging and thus to avoid shutdown of the unit because of clogging, to control the costs and to limit the consumption of adsorbent.
  • said optional pre-treatment stage a0) is carried out in a section for scrubbing with an aqueous solution, for example water, or an acidic or basic solution.
  • This scrubbing section can contain items of equipment which make it possible to bring the feedstock into contact with the aqueous solution and to separate the phases so as to obtain, on the one hand, the pretreated feedstock and, on the other hand, the aqueous solution comprising impurities.
  • These items of equipment can include, for example, a stirred reactor, a decanter, a mixer-decanter and/or a cocurrentwise or countercurrentwise scrubbing column.
  • the stage of pretreatment a0) by filtration comprises at least one filter, the size of the pores of which is less than 10 ⁇ m and preferably greater than 5 ⁇ m, followed by a filtration system, the size of the pores of which is less than 2 ⁇ m and preferably less than 1 ⁇ m.
  • the stage of pretreatment a0) by filtration comprises at least one filter, the size of the pores of which is less than 10 ⁇ m and preferably greater than 5 ⁇ m, followed by an electrostatic precipitation system.
  • these reactors operate in permutable mode, known as PRS for Permutable Reactor System, or also “lead and lag”.
  • PRS Permutable Reactor System
  • the combination of at least two reactors in PRS mode makes it possible to isolate a reactor, to discharge the spent catalyst, to recharge the reactor with fresh catalyst and to bring said reactor back into service without shutting down the process.
  • the PRS technology is described in particular in Patent FR 2 681 871.
  • the hydrogenation reaction section of stage a) comprises two reactors operating in permutable mode.
  • reactor internals for example of filter plate type, can be used to prevent the plugging of the reactor(s).
  • An example of a filter plate is described in Patent FR 3 051 375.
  • the ratio by weight, expressed as metal oxide, of the metal (or metals) from group VIB with respect to the metal (or to the metals) from group VIII is preferably of between 1 and 20 and in a preferred way between 2 and 10.
  • the support of said hydrogenation catalyst is preferably chosen from alumina, silica, silicas-aluminas, magnesia, clays and their mixtures.
  • Said support can include dopant compounds, in particular oxides chosen from boron oxide, especially boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide and a mixture of these oxides.
  • said hydrogenation catalyst comprises an alumina support, optionally doped with phosphorus and optionally boron.
  • phosphorus pentoxide P 2 O 5 When phosphorus pentoxide P 2 O 5 is present, its concentration is less than 10% by weight, with respect to the weight of the alumina, and advantageously at least 0.001% by weight, with respect to the total weight of the alumina.
  • boron trioxide B 2 O 3 When boron trioxide B 2 O 3 is present, its concentration is less than 10% by weight, with respect to the weight of the alumina, and advantageously at least 0.001%, with
  • Said hydrogenation catalyst is, for example, in the form of extrudates.
  • stage a) can employ, in addition to the hydrogenation catalyst(s) described above, moreover at least one hydrogenation catalyst used in stage 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 with respect to the weight of said catalyst, and less than 5% by weight of molybdenum and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, expressed as molybdenum oxide MoO 3 with respect to the weight of said catalyst, on an alumina support.
  • This catalyst not highly loaded with metals, can be preferably placed upstream or downstream of the hydrogenation catalyst(s) described above, preferably upstream.
  • stage a) can employ, upstream of the hydrogenation catalyst(s), at least one guard bed containing adsorbents of alumina, silica-alumina, zeolite and/or active carbon type optionally containing metals from group VIB and/or VIII.
  • Use may also be made of a series of guard beds with particles of different diameters, in particular a series of guard beds having decreasing diameters in the direction of the circulation of the feedstock (also referred to as “grading”).
  • the heat given off by the saturation of the double bonds makes it possible to raise the temperature of the reaction medium and to initiate the hydrotreating reactions, in particular the removal, at least partly, of other contaminants, such as, for example, silicon and chlorine.
  • other contaminants such as, for example, silicon and chlorine.
  • at least 50% and more preferentially at least 75% of the chlorine and of the silicon of the initial feedstock are removed during stage a).
  • the hydrogenated effluent obtained on conclusion of the hydrogenation stage a) is sent, preferably directly, to the hydrotreating stage b).
  • the treatment process comprises a hydrotreating stage b) carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst, said hydrotreating reaction section being fed at least with the feedstock, optionally pretreated in stage a0), or said hydrogenated effluent resulting from stage a) and a gas stream comprising hydrogen, said hydrotreating reaction section being employed at an average temperature between 250 and 430° C., a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁇ 1 , in order to obtain a hydrotreated effluent.
  • stage b) carries out hydrotreating reactions well known to a person skilled in the art and more particularly hydrotreating reactions such as the hydrogenation of aromatics, hydrodesulfurization and hydrodenitrogenation. Furthermore, the hydrogenation of the olefins and of the remaining halogen compounds and also the hydrodemetallization are continued.
  • Said hydrotreating reaction section is advantageously employed at a pressure equivalent to that used in the reaction section of the hydrogenation stage a), and generally at a higher average temperature than that of the reaction section of the hydrogenation stage a).
  • said hydrotreating reaction section is advantageously implemented at an average hydrotreating temperature between 250 and 430° C., preferably between 280 and 380° C., at a hydrogen partial pressure between 1.0 and 10.0 MPa abs. and at an hourly space velocity (HSV) between 0.1 and 10.0 h ⁇ 1 , preferably between 0.1 and 5.0 h ⁇ 1 , preferentially between 0.2 and 2.0 h ⁇ 1 , in a preferred way between 0.2 and 1 h ⁇ 1 .
  • HSV hourly space velocity
  • the hydrogen coverage in stage b) is advantageously of between 100 and 1500 Sm 3 of hydrogen per m 3 of fresh feedstock, preferably between 200 and 1000 Sm 3 of hydrogen per m 3 of fresh feedstock and in a preferred way between 250 and 800 Sm 3 of hydrogen per m 3 of fresh feedstock.
  • the definitions of the average temperature (WABT), of the HSV and of the hydrogen coverage correspond to those described above.
  • the hydrotreating stage is preferably carried out in a fixed bed. It can also be carried out in an ebullated bed, in an entrained bed or in a moving bed.
  • an additional stage of hydrotreating in a fixed bed can be carried out, under the same ranges of operating conditions, after that in an ebullated bed, in an entrained bed or in a moving bed, with or without intermediate separation of a gas stream.
  • the treatment process comprises a hydrotreating stage b) carried out in a hydrotreating reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreating catalyst.
  • Said hydrotreating reaction section is fed at least with the feedstock or said hydrogenated effluent resulting from stage a) and a gas stream comprising hydrogen, advantageously at the first catalytic bed of the first reactor in operation.
  • An injection of at least a part of the feedstock or of the hydrogenated effluent resulting from stage a) and/or at least a part of hydrogen between the different catalytic beds is also possible.
  • the reaction section of said stage b) can furthermore also be fed with at least a part of the liquid effluent resulting from stage c) and/or with at least a part of one of the effluents from stage f).
  • said hydrotreating catalyst comprises a support, preferably an inorganic support, and at least one metal element having a hydro-dehydrogenating function.
  • Said metal element having a hydro-dehydrogenating function advantageously comprises at least one element from group VIII, preferably chosen from the group consisting of nickel and cobalt, and/or at least one element from group VIB, preferably chosen from the group consisting of molybdenum and tungsten.
  • the total content, expressed as oxides, of the metal elements from groups VIB and VIII is preferably between 0.1% and 40% by weight, preferentially from 5% to 35% by weight, with respect to the total weight of the catalyst.
  • the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively.
  • the support of said hydrotreating catalyst is advantageously chosen from alumina, silica, silicas-aluminas, magnesia, clays and their mixtures.
  • Said support can additionally include dopant compounds, in particular oxides chosen from boron oxide, especially boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide and a mixture of these oxides.
  • said hydrotreating catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally boron.
  • stage b) can employ, upstream of the hydrogenation catalyst(s), at least one guard bed or a series of guard beds of “grading” type as described above for stage a).
  • the hydrotreating stage b) makes possible the hydrogenation of at least 80% and preferably of all of the olefins remaining after the hydrogenation stage a), but also the conversion, at least partly, of other impurities present in the feedstock, such as the aromatic compounds, the metal compounds, the sulfur compounds, the nitrogen compounds, the halogen compounds (in particular the chlorine compounds) and the oxygen compounds.
  • the nitrogen content at the outlet of stage b) is less than 100 ppm by weight.
  • the sulfur content at the outlet of stage b) is less than 100 ppm by weight.
  • Stage b) can also make it possible to further reduce the content of contaminants, such as that of the metals, in particular the silicon content.
  • the content of metals at the outlet of stage b) is less than 10 ppm by weight, in a preferred way less than 2 ppm by weight, and the silicon content is less than 5 ppm by weight.
  • a stream containing a sulfiding agent can be injected upstream of the optional pretreatment stage a0), of the optional hydrogenation stage a) and/or of the hydrotreating stage b) and/or upstream of one of the optional hydrocracking stages g), when they are present, preferably upstream of the hydrogenation stage a) and/or the hydrotreating stage b), in order to ensure a sufficient amount of sulfur to form the active entity of the catalyst (in sulfide form).
  • Said sulfur-containing compounds are advantageously chosen from alkyl disulfides, such as, for example, dimethyl disulfide (DMDS), alkyl sulfides, such as, for example, dimethyl sulfide, thiols, such as, for example, n-butyl mercaptan (or 1-butanethiol), and polysulfide compounds of tert-nonyl polysulfide type.
  • the catalyst can also be sulfided by the sulfur contained in the feedstock to be desulfurized.
  • the catalyst is sulfided in situ in the presence of a sulfiding agent and of a hydrocarbon feedstock.
  • the catalyst is sulfided in situ in the presence of the feedstock additivated with dimethyl disulfide.
  • the injection of a sulfiding agent is in particular necessary at the start of the catalytic cycle, the time that the H 2 S is formed in order to be separated in stage d) and recycled upstream of stage a) and/or of stage b) and/or of stage g), or also upstream of the selective hydrogenation stage of the pretreatment a0). Additional injections throughout the catalytic cycle may be necessary in order to compensate for the natural loss.
  • the fact of being able to recycle a gas phase containing the H 2 S without the NH 3 by the present invention makes it possible to considerably reduce the consumption of the sulfiding agent.
  • the treatment process comprises a separation stage c), advantageously carried out in at least one scrubbing/separation section, fed at least with the hydrotreated effluent resulting from stage b), and optionally with the hydrocracked effluent resulting from the optional stages g) and g′), and an aqueous solution, in order to obtain at least a gaseous effluent, a first aqueous effluent and a hydrocarbon effluent.
  • the gaseous effluent can also form the subject of additional separation(s) for the purpose of recovering at least one hydrogen-rich gas and/or light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent separately or as a mixture to one or more furnaces of the steam cracking stage h) so as to increase the overall yield of olefins.
  • additional separation(s) for the purpose of recovering at least one hydrogen-rich gas and/or light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent separately or as a mixture to one or more furnaces of the steam cracking stage h) so as to increase the overall yield of olefins.
  • the hydrocarbon effluent resulting from the separation stage c) is sent, partly or completely, either directly to the inlet of a steam cracking unit or to an optional fractionation stage f).
  • the liquid hydrocarbon effluent is sent, partly or completely, to a fractionation stage f).
  • the first aqueous effluent obtained on conclusion of stage c) advantageously comprises ammonium salts and/or hydrochloric acid, and also dissolved H 2 S and NH 3 .
  • This separation stage c) makes it possible in particular to remove the ammonium chloride salts, which are formed by reaction between the chloride ions, released by the hydrogenation of the chlorine compounds in HCl form, in particular during stages a) and b), followed by dissolution in the water, and the ammonium ions, generated by the hydrogenation of the nitrogen compounds in NH 3 form, in particular during stage b), and/or contributed by the injection of an amine, followed by dissolution in the water, and thus to limit the risks of plugging, in particular in the transfer lines and/or in the sections of the process of the invention and/or the transfer lines to the steam cracker, due to the precipitation of the ammonium chloride salts.
  • This stage c) also makes it possible to remove the hydrochloric acid formed by the reaction of the hydrogen ions and the chloride ions.
  • This stage c) also makes it possible to remove the ammonium sulfide salts ((NH 4 ) 2 S) which are formed by reaction between the H 2 S resulting from the hydrodesulfurization of the sulfur compounds and the NH 3 .
  • a stream containing a nitrogen compound such as an amine, for example monoethanolamine, diethanolamine and/or monodiethanolamine
  • a nitrogen compound such as an amine, for example monoethanolamine, diethanolamine and/or monodiethanolamine
  • a nitrogen compound such as an amine, for example monoethanolamine, diethanolamine and/or monodiethanolamine
  • a stream containing a nitrogen compound can be injected upstream of the selective hydrogenation stage of the pretreatment a0) and/or upstream of the hydrogenation stage a) and/or between the hydrogenation stage a) and the hydrotreating stage b) and/or between the hydrocracking stage g) and the separation stage c), preferably upstream of the hydrogenation stage a), in order to ensure a sufficient amount of ammonium ions to combine with the chloride ions formed during the hydrotreating stage, thus making it possible to limit the formation of hydrochloric acid and thus to limit the corrosion downstream of the separation section.
  • a nitrogen compound such as an amine, for
  • said gas phase containing the NH 3 resulting from stage e) can also be used as nitrogen compound.
  • the separation stage c) comprises an injection of an aqueous solution, preferably an injection of water, into the hydrotreated effluent resulting from stage b), or the hydrocracked effluent resulting from the optional stage g), upstream of the scrubbing/separation section, so as to dissolve, at least partly, ammonium chloride salts and/or hydrochloric acid and thus to improve the removal of the chlorinated impurities and to reduce the risks of pluggings due to an accumulation of the ammonium chloride salts.
  • the separation stage c) is advantageously carried out at a temperature of between 20 and 450° C., preferentially between 100 and 440° C., preferably between 200 and 420° C. It is important to operate in this temperature range (and thus not to excessively cool the hydrotreated effluent) at the risk of plugging in the lines due to the precipitation of the ammonium chloride salts.
  • the separation stage c) is carried out at a pressure close to that employed in stages a) and/or b), preferably between 1.0 and 10.0 MPa, so as to facilitate the recycling of hydrogen.
  • the separation stage can advantageously be carried out by any method known to a person skilled in the art, such as, for example, the combination of one or more separator(s) (drum(s)) and/or one or more stripping columns, it being possible for this or these separator(s) (drum(s)) and/or columns to be optionally fed with a stripping gas, for example a hydrogen-rich gas stream.
  • a stripping gas for example a hydrogen-rich gas stream.
  • the scrubbing/separation section of stage c) can, at least partly, be made of common or separate items of scrubbing and separation equipment.
  • the separation stage c) comprises the injection of an aqueous solution into the hydrotreated effluent resulting from stage b), followed by the scrubbing/separation section advantageously comprising a phase of separation which makes it possible to obtain at least one first aqueous effluent charged with ammonium salts, a scrubbed liquid hydrocarbon effluent and a partially scrubbed gaseous effluent.
  • Said first aqueous effluent charged with ammonium salts and the scrubbed liquid hydrocarbon effluent can subsequently be separated in a knockout drum in order to obtain said hydrocarbon effluent and said first aqueous effluent.
  • Said partially scrubbed gaseous effluent can, in parallel, be introduced into a scrubbing column where it circulates countercurrentwise to an aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrotreated effluent, which makes it possible to remove, at least partly, preferably completely, the hydrochloric acid contained in the partially scrubbed gaseous effluent and to thus obtain said gaseous effluent, preferably essentially comprising hydrogen, and an acidic aqueous stream.
  • Said first aqueous effluent resulting from the knockout drum can optionally be mixed with said acidic aqueous stream, and be used, optionally as a mixture with said acidic aqueous stream, in a water recycling circuit for feeding the separation stage c) with said aqueous solution upstream of the scrubbing/separation section and/or with said aqueous stream in the scrubbing column.
  • Said water recycling circuit can comprise a supply of water and/or of a basic solution and/or a bleed making it possible to discharge the dissolved salts.
  • the separation stage c) can advantageously comprise a “high-pressure” scrubbing/separation section which operates at a pressure close to the pressure of the hydrogenation stage a) and/or of the hydrotreating stage b) and/or of the optional hydrocracking stage g), preferably between 1.0 and 10.0 MPa, in order to facilitate the recycling of hydrogen.
  • This optional “high-pressure” section of stage c) can be supplemented by a “low-pressure” section, in order to obtain a hydrocarbon effluent devoid of a portion of the gases dissolved at high pressure and intended to be treated directly in a steam cracking process or optionally to be sent into the fractionation stage f).
  • the separation stage c) comprises the following substages:
  • the treatment process can comprise a separation stage c1), fed with the hydrotreated effluent resulting from stage b), said stage being carried out at a temperature of between 200 and 450° C. and at a pressure substantially identical to the pressure of stage b), in order to obtain at least a gaseous effluent and a liquid effluent, a part of which can be recycled upstream of stage a) and/or of stage b).
  • the separation stage c1) is a separation stage said to be a high-pressure or medium-pressure high-temperature separation stage, also known to a person skilled in the art under the name HHPS (Hot High Pressure Separator).
  • this stage c1) preferably employs a “hot high-pressure” separator, the pressure being substantially equal to the operating pressure of stage b).
  • the term “pressure substantially equal to the pressure of stage b)” is understood to mean the pressure of stage b) with a pressure difference of between 0 and 1 MPa, preferably of between 0.005 and 0.3 MPa and particularly preferably of between 0.01 and 0.2 MPa, with respect to the pressure of stage b).
  • the pressure of stage c1) is the pressure of stage b) decreased by pressure drops.
  • the temperature at which the separation is carried out is of between 200 and 450° C., preferably of between 220 and 330° C. and particularly preferably of between 240 and 300° C.
  • the separation is carried out at a temperature which is the highest possible but less than or equal to the outlet temperature of stage b), which makes it possible to avoid or to limit reheating (and thus a need for heat) of the effluent from stage b).
  • the effluent from stage b) can be reheated or cooled before the separation.
  • This separation stage c1) can advantageously be carried out by any method known to a person skilled in the art, such as, for example, the combination of one or more separator(s) (drum(s)) and/or one or more stripping columns, it being possible for this or these separator(s) (drum(s)) and/or columns to be optionally fed with a stripping gas, for example a hydrogen-rich gas stream.
  • stage c) is carried out with a single separator (drum).
  • a part of the liquid effluent can be recycled upstream of stage a) and/or of stage b) and/or upstream of the selective hydrogenation stage of the pretreatment a0).
  • the recycling of a part of the product obtained to or upstream of at least one of the reaction stages advantageously makes it possible, on the one hand, to dilute the impurities and, on the other hand, to control the temperature in the reaction stage(s), in which the reactions involved can be highly exothermic.
  • the amount of recycled liquid effluent resulting from stage c), that is to say the recycled fraction of product obtained is adjusted so that the ratio by weight of the recycle stream from stage c) to the feedstock comprising a plastics pyrolysis oil, that is to say the feedstock to be treated feeding the overall process, is less than or equal to 10, preferably less than or equal to 7, and preferentially greater than or equal to 0.001, preferably greater than or equal to 0.01 and in a preferred way greater than or equal to 0.1.
  • the amount of recycled liquid effluent resulting from stage c) is adjusted so that the ratio by weight of the recycle stream to the feedstock comprising a plastics pyrolysis oil is of between 0.01 and 10, preferably of between 0.1 and 7 and particularly preferably of between 0.2 and 5.
  • This recycle ratio makes it possible in particular to control the rise in the temperature in stage a). This is because, when the recycle ratio is high, the rate of dilution of the feedstock is high, and the rise in temperature at the beginning of the reaction section of stage a), in particular due to the hydrogenation reactions of the diolefins, is thus controllable by the dilution effect.
  • the high-pressure and high-temperature separation makes it possible, on the one hand, to maximize the recovery of energy by the hot recycle of a part of the liquid effluent. This is because the energy in order to reach the inlet temperature necessary in stage a) and/or stage b) can be at least partly contributed by the heat of a part of the liquid effluent resulting from stage c) and also makes it possible to reduce, indeed even eliminate, an optional preheating by direct heating of the feedstock beyond a temperature of greater than 200° C. in order to prevent the formation of gums. Furthermore, the fact of recycling at least a part of the liquid effluent at high pressure makes it possible to economize on energy for its pressurization in stage a) and/or stage b).
  • the high-pressure and high-temperature separation makes it possible, on the other hand, to minimize the amount of light fraction (hydrocarbon cut comprising compounds having a boiling point of less than or equal to 175° C. or naphtha) contained in the liquid effluent recycled in stage a) and/or stage b).
  • this temperature virtually all of the light fraction of the effluent (naphtha) leaves as gaseous effluent to the separation/scrubbing stage c2), whereas, as liquid phase, there is predominantly the heavy fraction of the feedstock (hydrocarbon cut comprising compounds having a boiling point of greater than 175° C. or middle distillates).
  • the pH 2 p is favoured in stage a) and/or in stage b) because the light fraction (naphtha) might partly evaporate and lower the pH 2 p if it were not at least partly removed during the high-pressure and high-temperature separation.
  • the removal of the light fraction comprising naphtha can optionally be increased by a slight pressure reduction upstream of at least one separator used in stage c1), even if this use is not preferred as a result of the energy loss linked to the pressure reduction.
  • Another option for increasing the removal of the light faction comprising naphtha can consist in carrying out a stripping, for example by injecting a hydrogen-rich gas in stage c1).
  • At least a part of the hydrotreated liquid effluent resulting from stage c) can advantageously be either cooled, or preheated, if necessary, or kept at the same temperature as at the outlet of the separation stage c), before being advantageously recycled upstream of the hydrogenation stage a) and/or of the hydrotreating stage b), according to the temperature and the flow rate of feedstock and hydrogen, so that the temperature of the incoming stream, comprising said feedstock as a mixture with at least a part of said liquid effluent resulting from stage c) and a hydrogen-rich gas, is of between 140 and 430° C., preferably between 220 and 350° C. and particularly preferably between 260 and 330° C.
  • said effluent optionally passes through at least one exchanger and/or at least one oven before being recycled upstream of stage a) and/or stage b), so as to adjust the temperature of said recycled liquid effluent.
  • said effluent optionally passes through at least one exchanger and/or at least one cooling tower before being recycled upstream of stage a) and/or stage b), so as to adjust the temperature of said recycled liquid effluent.
  • the feedstock before being mixed with at least a part of the effluent resulting from stage c), can be preheated by direct heating to a temperature ranging up to 200° C., preferably up to 180° C. and particularly preferably up to 150° C. Above this temperature, contact with a wall during the direct heating can bring about the formation of gums and/or of coke, which can cause fouling and an increase in the pressure drop of the system for heating the feedstock and also of the bed(s) of catalysts.
  • the heating of the feedstock to a temperature above 150° C., preferably above 180° C. and particularly preferably above 200° C. is preferably carried out by indirect heating by at least a part of the effluent resulting from stage c).
  • the rise in temperature above 150° C., preferably above 180° C. and particularly preferably above 200° C. of the feedstock is brought about by mixing with a hotter liquid and not by contact with a heated wall.
  • the heating of the feedstock to a temperature above 150° C., preferably above 180° C. and particularly preferably above 200° C. is carried out by ovens or exchangers proportioned in order to have a very low wall temperature in comparison with the temperature of the feedstock, for example an electric oven.
  • the feedstock is entirely heated by indirect heating by at least a part of the effluent resulting from stage c).
  • the feedstock is not preheated before being mixed with at least a part of the effluent resulting from stage c).
  • the feedstock is not heated by indirect heating by at least a part of the effluent resulting from stage c).
  • the feedstock and the part of the recycled effluent resulting from stage c) are mixed, the part of the recycled effluent resulting from stage c) having substantially the same temperature as or a lower temperature than the feedstock.
  • Another heating stream advantageously consists of a hydrogen-rich gaseous effluent originating from the hydrogen supply and/or of the gaseous effluent resulting from the separation stage c). At least a part of this hydrogen-rich gaseous effluent originating from the hydrogen supply and/or of the gaseous effluent resulting from the separation stage c) is advantageously injected as a mixture with at least a part of the liquid effluent resulting from stage c) or separately, upstream of stage a) and/or of stage b).
  • the hydrogen-rich gas stream can thus be advantageously either preheated as a mixture with at least a part of the liquid effluent or preheated separately before mixing, preferably by optional passage through at least one exchanger and/or at least one oven or any other heating means known to a person skilled in the art.
  • the treatment process comprises a separation stage c2), advantageously carried out in at least one scrubbing/separation section, fed with the first gaseous effluent and another part of the liquid effluent resulting from stage c1) and an aqueous solution, said stage being carried out at a temperature of between 20 and less than 200° C. and at a pressure substantially identical to or less than the pressure of stage b), in order to obtain at least a gaseous effluent, a first aqueous effluent and a hydrocarbon effluent.
  • the pressure of stage c2) is the pressure of stage b) decreased by pressure drops.
  • the fact of operating at least a part of the separation stage c2) at a pressure substantially identical to the operating pressure of stage b) furthermore facilitates the recycling of hydrogen.
  • the separation stage c2) can also be carried out at a lower pressure than the pressure of stage b).
  • the separation stage c2) can also comprise a (first) stage of separation at a pressure substantially equal to the operating pressure of stage b), followed by at least one other separation stage carried out at a temperature identical to or lower than and at a pressure lower than each preceding separation stage of stage c2).
  • the temperature at which the separation of stage c2) is carried out is of between 20 and less than 200° C., preferably of between 25 and 120° C. and particularly preferably of between 30 and 70° C.
  • stage c2) can at least partly be made of common or separate items of scrubbing and separation equipment, these items of equipment being well known (knockout drums which can be operated at various pressures and temperatures, pumps, heat exchangers, scrubbing columns, and the like).
  • the separation stage c2) can in particular be carried out the same as stage c) described above.
  • this stage c2) can in addition be fed with at least a part of the hydrocracked effluent resulting from an optional hydrocracking stage g).
  • At least a part of the hydrocarbon effluent resulting from stage c2) can be recycled as liquid quench upstream of stage a) and/or of stage b) and/or of stage g).
  • the injection of the hydrocarbon effluent resulting from stage c2) can be carried out at the first catalytic bed of the reaction section of stage a) and/or of stage b) and/or of stage g) or between the different catalytic beds of each section.
  • the hydrogenation reaction section of stage a) comprises two reactors operating in permutable mode, at least a part of the hydrocarbon effluent resulting from stage c2) can be recycled between the two reactors.
  • the treatment process comprises a stage d) of separation of the H 2 S contained in the first aqueous effluent, in order to obtain a gas phase containing the H 2 S and a second aqueous effluent, said gas phase containing the H 2 S being preferably, at least partly, recycled upstream of stage a) and/or stage b) and/or stage g).
  • Stage d) of separation of the H 2 S contained in the first aqueous effluent is advantageously carried out by stripping using a gas stream, preferably an inert gas stream, in a stripping column.
  • a stripping column is a distillation column in which a gas stream, preferably an inert gas stream, is injected at the column bottom.
  • the gas phase containing the H 2 S is recovered at the column top and a second aqueous effluent is recovered at the bottom of the column.
  • the inert gas stream can be hydrogen, nitrogen or steam.
  • stage d) is carried out by steam stripping.
  • Stripping using a gas stream preferably an inert gas stream, makes it possible to obtain a very low content of dissolved H 2 S in the second aqueous effluent at the bottom of the stripping column.
  • the stage d) of separation of the H 2 S is generally carried out at a pressure of between 0.5 and 1.5 MPa, preferably of between 0.5 and 1 MPa and particularly preferably of between 0.6 and 0.9 MPa.
  • the stripping is generally carried out at a temperature of between 80 and 150° C., preferably between 120 and 145° C. (at the top and bottom of the column, respectively).
  • the flow rate of the inert gas stream is generally such that the ratio of the flow rate of the inert gas stream, expressed in standard m 3 per hour (Sm 3 /h), to the flow rate of first aqueous effluent to be treated, expressed in m 3 per hour at standard conditions (15° C., 0.1 MPa), is of between 50 and 600 Sm 3 /m 3 , preferably between 200 and 400 Sm 3 /m 3 .
  • Standard m 3 is understood to mean the amount of gas in a volume of 1 m 3 at 0° C. and 0.1 MPa.
  • a part of the gas phase at the top of the stripping column comprising the H 2 S and the inert gas stream (steam), is condensed and is preferably reinjected, at least partly, as liquid reflux into the upper part of the stripping column.
  • the condensation is generally carried out by cooling to a temperature of between 30 and 65° C., for example with cold water.
  • the liquid reflux makes it possible to control/reduce the temperature at the stripping column top.
  • Said gas phase containing the H 2 S withdrawn at the stripping column top is at least partly recycled upstream of stage a) and/or stage b) and/or also upstream of the hydrocracking stage g) and/or upstream of the selective hydrogenation stage of the pretreatment a0), when they are present, in order to act as sulfiding agent for the catalyst(s).
  • it Before its recycling, it can be subjected to at least one additional stage of purification, for example a contacting with liquid or a scrubbing with amines.
  • stage d) of separation of the H 2 S contained in the first aqueous effluent can also be carried out by liquid/liquid extraction, in which an inert solvent or a reactant is brought into contact with the aqueous effluent.
  • the treatment process comprises a stage e) of separation of the NH 3 contained in the second aqueous effluent resulting from stage d), in order to obtain a gas phase containing the NH 3 and a third aqueous effluent, said gas phase containing the NH 3 being preferably, at least partly, recycled upstream of stage a) and/or stage b) and/or stage g).
  • Stage e) of separation of the NH 3 contained in the second aqueous effluent is advantageously carried out by stripping using an inert gas stream in a stripping column.
  • the gas phase containing NH 3 is recovered at the column top and a third aqueous effluent is recovered at the bottom of the column.
  • the inert gas stream can be hydrogen, nitrogen or steam.
  • stage e) is carried out by steam stripping.
  • the stripping using an inert gas stream makes it possible to obtain a very low content of dissolved NH 3 at the bottom of the stripping column, making it possible to recover a third aqueous effluent which can be introduced into a conventional wastewater treatment.
  • Stage e) of separation of the NH 3 is generally carried out at a pressure of between 0.1 and less than 0.5 MPa, preferably of between 0.05 and 0.2 MPa.
  • the stripping is generally carried out at a temperature of between 80 and 150° C., preferably between 120 and 145° C. (at the top and bottom of the column, respectively).
  • the flow rate of the inert gas stream is generally such that the ratio of the flow rate of the inert gas stream, expressed in standard m 3 per hour (Sm 3 /h), to the flow rate of feedstock to be treated, expressed in m 3 per hour at standard conditions (15° C., 0.1 MPa), is of between 50 and 600 Sm 3 /m 3 , preferably between 200 and 400 Sm 3 /m 3 .
  • Standard m 3 is understood to mean the amount of gas in a volume of 1 m 3 at 0° C. and 0.1 MPa.
  • a part of the gas phase at the top of the stripping column comprising the NH 3 and the inert gas stream (steam), is condensed and is preferably reinjected, at least partly, as liquid reflux into the upper part of the stripping column.
  • the condensation is generally carried out by cooling to a temperature of between 30 and 65° C., for example with cold water.
  • the liquid reflux makes it possible to control/reduce the temperature at the stripping column top.
  • said gas phase containing the NH 3 can be, at least partly, recycled upstream of stage a) and/or stage b) and/or stage g), and/or also upstream of the selective hydrogenation stage a0), advantageously in stoichiometric amounts suitable for the formation of the salts during the separation/scrubbing stage c).
  • the process according to the invention can comprise a stage of fractionation of all or part, preferably of the whole, of the hydrocarbon effluent resulting from stage c), in order to obtain at least a gas stream and at least two liquid hydrocarbon streams, said two liquid hydrocarbon streams being at least a first hydrocarbon cut comprising compounds having a boiling point of less than or equal to 175° C. (naphtha cut), in particular between 8° and 175° C., and a second hydrocarbon cut comprising compounds having a boiling point of greater than 175° C. (middle distillates cut).
  • Stage f) makes it possible in particular to remove the gases dissolved in the liquid hydrocarbon effluent, such as, for example, ammonia, hydrogen sulfide and light hydrocarbons having from 1 to 4 carbon atoms.
  • the optional fractionation stage f) is advantageously carried out at a pressure of less than or equal to 3.0 MPa abs., preferably between 0.5 and 2.5 MPa abs.
  • stage f) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit comprising a reflux drum.
  • Said stripping column is fed with the liquid hydrocarbon effluent resulting from stage c) and with a steam stream.
  • the liquid hydrocarbon effluent resulting from stage c) can optionally be heated before entering the stripping column.
  • the lightest compounds are entrained at the column top and into the reflux circuit comprising a reflux drum in which a gas/liquid separation takes place.
  • the gas phase which comprises the light hydrocarbons is withdrawn from the reflux drum as a gas stream.
  • the hydrocarbon cut comprising compounds having a boiling point of less than or equal to 175° C. is advantageously withdrawn from the reflux drum.
  • the hydrocarbon cut comprising compounds having a boiling point of greater than 175° C. is advantageously withdrawn at the stripping column bottom.
  • the naphtha cut comprising compounds having a boiling point of less than or equal to 175° C. resulting from stage f) is fractionated to give a heavy naphtha cut comprising compounds having a boiling point between 80 and 175° C. and a light naphtha cut comprising compounds having a boiling point of less than 80° C., at least a part of said heavy naphtha cut being sent to an aromatic complex comprising at least one stage of reforming of the naphtha for the purpose of producing aromatic compounds.
  • at least a part of the light naphtha cut is sent into the steam cracking stage h) described below.
  • the gaseous effluent(s) resulting from the fractionation stage f) can form the subject of additional purification(s) and separation(s) for the purpose of recovering at least light hydrocarbons, in particular ethane, propane and butane, which can advantageously be sent, separately or as a mixture, to one or more furnaces of the steam cracking stage h) so as to increase the overall yield of olefins.
  • the compounds having a boiling point of greater than 175° C. have a high BMCI and contain, with respect to lighter compounds, more naphthenic, naphthenic-aromatic and aromatic compounds, thus leading to a higher C/H ratio.
  • This high ratio is a cause of coking in the steam cracker, thus requiring steam cracking furnaces dedicated to this cut.
  • these compounds can be at least partly converted into light compounds by hydrocracking, a cut generally favoured for a steam cracking unit.
  • the process of the invention can comprise a hydrocracking stage g) carried out in a hydrocracking reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a part of said hydrocarbon effluent resulting from stage c) and/or with at least a part of the second hydrocarbon cut comprising compounds having a boiling point of greater than 175° C. resulting from stage f) and a gas stream comprising hydrogen, said hydrocracking reaction section being employed at an average temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁇ 1 , in order to obtain a first hydrocracked effluent.
  • said hydrocracking reaction section is implemented at a pressure equivalent to that used in the reaction section of the hydrogenation stage a) or of the hydrotreating stage b).
  • the hydrocracked effluent can, at least partly, be recycled in the hydrogenation stage a) and/or in the hydrotreating stage b) and/or in the separation stage c). Preferably, it is recycled in the separation stage c).
  • the hydrocracking stage can be carried out in one stage (stage g)) or two stages (stages g) and g′)).
  • stage g stage g
  • stages g and g′ stages
  • a separation of the effluent resulting from the first hydrocracking stage g) is carried out, making it possible to obtain a hydrocarbon cut comprising compounds having a boiling point of greater than 175° C. (middle distillates cut), which cut is introduced into the second hydrocracking stage g′) comprising a dedicated second hydrocracking reaction section different from the first hydrocracking reaction section g).
  • This configuration is particularly suitable when it is desired to produce only a naphtha cut.
  • the second hydrocracking stage g′) is carried out in a hydrocracking reaction section, employing at least one fixed-bed reactor having n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a part of the first hydrocracked effluent resulting from the first hydrocracking stage g) and a gas stream comprising hydrogen, said hydrocracking reaction section being employed at an average temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁇ 1 , in order to obtain a second hydrocracked effluent.
  • the preferred operating conditions and the catalysts used in the second hydrocracking stage are those described for the first hydrocracking stage.
  • the operating conditions and catalysts used in the two hydrocracking stages can be identical or different.
  • Said second hydrocracking stage is preferably carried out in a hydrocracking reaction section comprising at least one, preferably between one and five, fixed-bed reactor(s) having n catalytic beds, n being an integer greater than or equal to 1, preferably of between 1 and 10, in a preferred way of between 2 and 5, said bed(s) each comprising at least one, and preferably not more than ten, hydrocracking catalyst(s).
  • the conversion per pass is limited by the use of a high recycle ratio over the loop of the second hydrocracking stage.
  • This ratio is defined as the ratio of the feed flow rate of stage g′) to the flow rate of the feedstock of stage a) or of stage b); preferentially, this ratio is of between 0.2 and 4, in a preferred way between 0.5 and 2.5.
  • the hydrocracked effluent from the second hydrocracking stage g′) can, at least partly, be recycled in the hydrogenation stage a) and/or in the hydrotreating stage b) and/or in the separation stage c). Preferably, it is recycled in the separation stage c).
  • the hydrocracking stage(s) thus does (do) not necessarily make it possible to convert all the hydrocarbon compounds having a boiling point of greater than 175° C. (middle distillates cut) into hydrocarbon compounds having a boiling point of less than or equal to 175° C. (naphtha cut).
  • the fractionation stage f there may thus remain a more or less significant proportion of compounds having a boiling point of greater than 175° C.
  • at least a part of this unconverted cut can be introduced into a second hydrocracking stage g′). Another part can be bled off.
  • said bleed can be of between 0% and 10% by weight of the cut comprising compounds having a boiling point of greater than 175° C., with respect to the incoming feedstock, and preferably between 0.5% and 5% by weight.
  • the hydrocracking stage(s) operate(s) in the presence of at least one hydrocracking catalyst.
  • the hydrocracking catalyst(s) used in the hydrocracking stage(s) are conventional hydrocracking catalysts known to a person skilled in the art, of bifunctional type combining an acid function with a hydro-dehydrogenating function and optionally at least one binding matrix.
  • the acid function is contributed by supports of high specific surface area (generally 150 to 800 m 2 /g) exhibiting a surface acidity, such as halogenated (in particular chlorinated or fluorinated) aluminas, combinations of boron and aluminium oxides, amorphous silicas-aluminas and zeolites.
  • the hydro-dehydrogenating function is contributed by at least one metal from group VIB of the Periodic Table and/or at least one metal from group VIII.
  • the hydrocracking catalyst(s) comprise a hydro-dehydrogenating function comprising at least one metal from group VIII chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, and preferably from cobalt and nickel.
  • said catalyst(s) also comprise at least one metal from group VIB chosen from chromium, molybdenum and tungsten, alone or as a mixture, and preferably from molybdenum and tungsten.
  • Hydro-dehydrogenating functions of NiMo, NiMoW or NiW type are preferred.
  • the content of metal from group VIII in the hydrocracking catalyst(s) is advantageously of between 0.5% and 15% by weight and preferably between 1% and 10% by weight, the percentages being expressed as percentage by weight of oxides, with respect to the total weight of the catalyst.
  • the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively.
  • the hydrocracking catalyst(s) can also optionally comprise at least one promoter element deposited on the catalyst and chosen from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (chlorine and fluorine preferred), optionally at least one element from group VIIB (manganese preferred) and optionally at least one element from group VB (niobium preferred).
  • the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina.
  • a preferred catalyst comprises, and preferably consists of, at least one metal from group VIB and optionally at least one non-noble metal from group VIII, at least one promoter element, and preferably phosphorus, at least one Y zeolite and at least one alumina binder.
  • Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, alumina and silica-alumina.
  • Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, a USY zeolite, alumina and silica-alumina.
  • the hydrocracking catalyst employed in the second hydrocracking stage comprises a hydro-dehydrogenating function comprising at least one noble metal from group VIII chosen from palladium and platinum, alone or as a mixture.
  • the content of noble metal from group VIII is advantageously of between 0.01% and 5% by weight and preferably between 0.05% and 3% by weight, the percentages being expressed as percentage by weight of oxides (PtO or PdO), with respect to the total weight of the catalyst.
  • the hydrocracking catalyst additionally comprises one or more organic compounds containing oxygen and/or nitrogen and/or sulfur.
  • a catalyst is often denoted by the term “additivated catalyst”.
  • the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide function or also compounds including a furan ring or also sugars.
  • the preparation of the catalysts of the hydrogenation, hydrotreating and hydrocracking stages is known and generally comprises a stage of impregnation of the metals from group VIII and from group VIB, when it is present, and optionally of the phosphorus and/or of the boron on the support, followed by drying, and then optionally by a calcination.
  • the preparation generally takes place by simple drying without calcination after introduction of the organic compound.
  • calcination is understood here to mean a heat treatment under a gas containing air or oxygen at a temperature of greater than or equal to 200° C.
  • the catalysts are generally subjected to a sulfidation in order to form the active entity.
  • the catalyst of stage a) can also be a catalyst used in its reduced form, thus involving a reduction stage in its preparation.
  • the gas stream comprising hydrogen which feeds the selective hydrogenation, hydrogenation, hydrotreating and hydrocracking reaction section, can consist of a supply of hydrogen and/or can consist of recycled hydrogen resulting in particular from the separation stage c).
  • an additional gas stream comprising hydrogen is advantageously introduced at the inlet of each reactor, in particular operating in series, and/or at the inlet of each catalytic bed starting from the second catalytic bed of the reaction section.
  • These additional gas streams are also referred to as cooling streams. They make it possible to control the temperature in the reactor in which the reactions carried out are generally highly exothermic.
  • Said hydrocarbon effluent or said hydrocarbon stream(s) thus obtained by treatment according to the process of the invention of a plastics pyrolysis oil exhibit(s) a composition compatible with the specifications for a feedstock at the inlet of a steam cracking unit.
  • the composition of the hydrocarbon effluent or of said hydrocarbon stream(s) is preferably such that:
  • the contents are given as relative concentrations by weight, percentages (%) by weight, part(s) per million (ppm) by weight or part(s) per billion (ppb) by weight, with respect to the total weight of the stream under consideration.
  • Any gaseous effluent and/or any liquid effluent resulting from at least one of the separation stages c), d) or e) or from the fractionation stage f) can be subjected to an optional stage of adsorption of heavy metals.
  • the gaseous effluents can in particular be the gaseous effluent resulting from stage c) and/or the gas phase containing the H 2 S resulting from stage d) and/or the gas phase containing NH 3 resulting from stage e) and/or the gaseous effluent resulting from the fractionation stage f).
  • the liquid effluents can in particular be the hydrocarbon effluent resulting from stage c) and/or the first and/or the second hydrocarbon cut resulting from stage f).
  • the optional adsorption stage makes it possible to eliminate or reduce the amount of metal impurities, in particular the amount of heavy metals, such as arsenic, zinc, lead and in particular mercury, possibly present in said gaseous and liquid effluents.
  • the metal impurities, and in particular the heavy metals are present in the feedstock.
  • Some impurities, in particular based on mercury, can be transformed in one of the stages of the process according to the invention. Their transformed form is easier to trap.
  • an optional stage of adsorption of a gaseous effluent and/or of a hydrocarbon effluent resulting from the process according to the invention is advantageously carried out in particular when at least one of these effluents or the feedstock respectively comprise more than 20 ppb by weight, in particular more than 15 ppb by weight, of metal elements of heavy metals (As, Zn, Pb, Hg, and the like), and in particular when at least one of these effluents or the feedstock respectively comprise more than 10 ppb by weight of mercury, more particularly more than 15 ppb by weight of mercury.
  • Said optional adsorption stage is advantageously carried out at a temperature between 20 and 250° C., preferably between 40 and 200° C., and at a pressure between 0.15 and 10.0 MPa abs., preferably between 0.2 and 1.0 MPa abs.
  • the hydrocarbon effluent resulting from the separation stage c), or at least one of the two liquid hydrocarbon streams resulting from the optional stage f), can be sent, completely or partly, to a steam cracking stage h).
  • the gaseous effluent(s) resulting from the separation stage c) and/or the fractionation stage f) and containing ethane, propane and butane can also be sent, completely or partly, to the steam cracking stage h).
  • the optional stage h) is carried out in several pyrolysis furnaces in parallel, so as to adapt the operating conditions to the various streams feeding stage h), in particular resulting from stage f), and also to manage the decoking times of the tubes.
  • a furnace comprises one or more tubes arranged in parallel.
  • a furnace can also denote a group of furnaces operating in parallel.
  • a furnace may be dedicated to the cracking of the hydrocarbon cut comprising compounds having a boiling point of less than or equal to 175° C.
  • the effluents from the various steam cracking furnaces are generally recombined before separation for the purpose of constituting an effluent.
  • the steam cracking stage h comprises the steam cracking furnaces but also the substages associated with the steam cracking which are well known to a person skilled in the art. These substages can in particular comprise heat exchangers, columns and catalytic reactors and recyclings to the furnaces.
  • a column generally makes it possible to fractionate the effluent for the purpose of recovering at least a light fraction comprising hydrogen and compounds having from 2 to 5 carbon atoms, and a fraction comprising pyrolysis petrol, and optionally a fraction comprising pyrolysis oil.
  • This steam cracking stage h) makes it possible to obtain at least one effluent containing olefins comprising 2, 3 and/or 4 carbon atoms (that is to say C 2 , C 3 and/or C 4 olefins), at satisfactory contents, in particular of greater than or equal to 30% by weight, in particular of greater than or equal to 40% by weight, indeed even of greater than or equal to 50% by weight, of total olefins comprising 2, 3 and 4 carbon atoms, with respect to the weight of the steam cracking effluent under consideration.
  • Said C 2 , C 3 and C 4 olefins can subsequently be advantageously used as polyolefin monomers.
  • the process for the treatment of a feedstock comprising a plastics pyrolysis oil preferably comprises the linking together of the following stages, and preferably in the order given:
  • All the embodiments can comprise and preferably consist of, in addition, a pretreatment stage a0).
  • All the embodiments can comprise and preferably consist of, in addition, a steam cracking stage h).
  • FIGS. 1 and 2 make possible a better understanding of the invention, without the latter being limited to the specific embodiments illustrated in FIGS. 1 and 2 .
  • the various embodiments presented can be used alone or in combination with one another, without limitation of combination.
  • FIG. 1 represents the diagram of a specific embodiment of the process of the present invention, comprising:
  • FIG. 2 represents the diagram of another specific embodiment of the process of the present invention which is based on the diagram of FIG. 1 .
  • This diagram comprises a stage c) carried out in two stages, then a fractionation stage f) and a hydrocracking stage g) in addition.
  • the hydrogenation stage a) and the hydrotreating stage b) are carried out as described in FIG. 1 .
  • the separation stage c), carried out in two stages, comprises in particular:
  • Stage d) of separation of the H 2 S and stage e) of separation of the NH 3 are carried out as described in FIG. 1 .
  • the recycling of the phase containing the H 2 S 20 is carried out in the same way. It can also, at least partly, be recycled in the hydrocracking stage g).
  • a stage f) of fractionation of the hydrocarbon effluent 13 is carried out which makes it possible to obtain at least a gaseous effluent 14 , a first hydrocarbon cut 15 comprising compounds having a boiling point of less than or equal to 175° C. (naphtha cut) and a second hydrocarbon cut 16 comprising compounds having a boiling point of greater than 175° C. (middle distillates cut).
  • stage f On conclusion of stage f), a part of the first hydrocarbon cut 15 comprising compounds having a boiling point of less than or equal to 175° C. can be sent to a steam cracking process (not represented). Another part of the first hydrocarbon cut 15 can feed the hydrogenation stage a) and/or the hydrotreating stage b) (recycling not represented).
  • the hydrocracked effluent 18 can be recycled between the separation stages c1) and c2) or also upstream of the separation stage c) (not represented).
  • FIGS. 1 and 2 Only the main stages, with the main streams, are represented in FIGS. 1 and 2 , in order to make it possible for the invention to be better understood. It is clearly understood that all the items of equipment required for the operation are present (drums, pumps, exchangers, ovens/furnaces, columns, and the like), even if not represented. It is also understood that gas streams rich in hydrogen (supply or recycle), as described above, can be injected at the inlet of each reactor or catalytic bed or between two reactors or two catalytic beds. Means well known to a person skilled in the art for the purification and recycling of hydrogen can also be employed.
  • the feedstock 1 treated in the process with a flow rate of 10 000 kg/h (10 T/h) is a plastics pyrolysis oil (that is to say, comprising 100% by weight of said plastics pyrolysis oil) exhibiting the characteristics indicated in Table 2.
  • the feedstock 1 is subjected to a hydrogenation stage a) carried out in a fixed-bed reactor and in the presence of hydrogen 2 and of a hydrogenation catalyst of NiMo-on-alumina type, under the conditions indicated in Table 3.
  • the conditions indicated in Table 3 correspond to conditions at the beginning of the cycle and the average temperature (WABT) is increased by 1° C. per month so as to compensate for the catalytic deactivation.
  • WABT average temperature
  • the effluent 5 resulting from the hydrogenation stage a) is subjected directly, without separation, to a hydrotreating stage b) carried out in a fixed bed and in the presence of hydrogen and of a hydrotreating catalyst of NiMo-on-alumina type under the conditions presented in Table 5.
  • the conditions indicated in Table 5 correspond to conditions at the beginning of the cycle and the average temperature (WABT) is increased by 1° C. per month so as to compensate for the catalytic deactivation.
  • the effluent 7 resulting from the hydrotreating stage b) is subjected to a separation stage c): a stream of water 10 is injected into the effluent resulting from the hydrotreating stage b); the mixture is subsequently treated in a column for scrubbing sour gases and knockout drums, in order to obtain a gas fraction and a liquid effluent.
  • the yields of the various fractions obtained after separation are shown in Table 6 (the yields correspond to the ratios of the amounts by weight of the various products obtained, with respect to the weight of feedstock upstream of stage a), expressed as percentage and denoted % w/w).
  • All or part of the liquid fraction obtained can subsequently be upgraded in a steam cracking stage for the purpose of forming olefins which can be polymerized for the purpose of forming recycled plastics.
  • the pyrolysis oil feedstock contains very little sulfur (170 ppm by weight).
  • This sulfur which exists in the form of sulfur-containing molecules, is hydrogenated in the reaction section and is converted into H 2 S.
  • This H 2 S in the form of a partial H 2 S pressure (pH 2 Sp) in the reactor, contributes to the maintenance of the sulfide phase of the NiMo-on-alumina catalysts. Nevertheless, the pH 2 Sp obtained with this content of sulfur-containing compounds in the feedstock (170 ppm by weight) is insufficient to keep the catalysts in the sulfide phase throughout the cycle. This results in a rapid deactivation of the activity of the catalyst if nothing is done.
  • H 2 S it is thus advisable to add H 2 S to the reaction system in order to achieve a sufficient pH 2 Sp.
  • This addition of H 2 S can be carried out in the form of an injection, at the inlet of the unit, into the pyrolysis oil feedstock, of dimethyl disulfide (DMDS).
  • DMDS readily decomposes as soon as it contacts the catalyst to give CH 4 and H 2 S, thus generating a sufficient pH 2 Sp to keep the catalysts in sulfide form. This way of operating causes a high consumption of DMDS harmful to the economics of the process.
  • Another way, forming the subject-matter of the invention is to recover the H 2 S which is discharged in the aqueous effluent using a twofold stripping of this aqueous effluent and to reinject this H 2 S at the inlet of the unit by dissolution in the pyrolysis oil feedstock.
  • the injection of DMDS and/or the recycling of H 2 S at the inlet of the unit can serve both to maintain a sufficient pH 2 Sp in the reaction system but also can serve to neutralize all the NH 3 resulting from the hydrogenation of the nitrogen-containing molecules. This is because the H 2 S reacts with the NH 3 to form ammonium sulfides which will be virtually completely scrubbed out and transferred into the aqueous effluent (stream 12 ), making it possible to free the gas stream at the top outlet of the stabilization column from the presence of ammonia (stream 11 ). This gas stream, freed from the presence of ammonia, can thus be sent directly to the steam cracker in order to maximize the production of olefins.
  • Case 1 Simple stripping of sour water and injection of DMDS only in order to maintain a pH 2 Sp sufficient to keep the catalysts in the sulfide phase.
  • Case 2 Twofold stripping of sour water in order to recycle, at the inlet of the unit, a stream predominant in H 2 S resulting from the top of the first stripping column only in order to maintain a pH 2 Sp sufficient to keep the catalysts in the sulfide phase. This case is in accordance with the invention.
  • Case 3 Simple stripping of sour water and injection of DMDS in order to maintain a pH 2 Sp sufficient to keep the catalysts in the sulfide phase and also in order to neutralize all the NH 3 and to deliver an NH 3 -free gas stream.
  • Case 4 Twofold stripping of sour water in order to recycle, at the inlet of the unit, a stream predominant in H 2 S resulting from the top of the first stripping column in order to maintain a pH 2 Sp sufficient to keep the catalysts in the sulfide phase and also in order to neutralize all the NH 3 and to deliver an NH 3 -free gas stream. This case is in accordance with the invention.
  • the invention makes it possible to save 19 kg/h of DMDS when it is a matter of maintaining a minimum pH 2 Sp for keeping the catalysts in sulfide form.

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US18/860,831 2022-04-29 2023-04-17 Method for treating plastic pyrolysis oil including an h2s recycling step Pending US20250313765A1 (en)

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FR3135090B1 (fr) 2025-11-28
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TW202407084A (zh) 2024-02-16
WO2023208636A1 (fr) 2023-11-02
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AU2023259466A1 (en) 2024-10-31

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