Method for producing olefins by steam decomposition using upgraded pyrolysis gases

Abstract

A method for producing olefins from feedstock including plastics and / or tires and / or solid recovered fuel, comprising the steps of: (a) pyrolysis of the feedstock including plastics and / or tires and / or solid recovered fuel in a pyrolysis unit to recover a first gaseous effluent containing at least a mixture of H2, CO, CO2 and C1-C6 hydrocarbons and a first liquid effluent containing C7+ hydrocarbons; (b) compression and cooling of the first gaseous effluent, and then separation of the compressed and cooled first gaseous effluent to obtain a second liquid effluent mainly containing C3+ hydrocarbons and a residual second gaseous effluent concentrated with H2, CO and CO2; (c) introduction of the second liquid effluent into a steam decomposition unit in the presence of water vapor.

Description

[Technical Field]

[0001] The present invention relates to the field of recycling plastics and / or tires and / or solid recovered fuel (SRF). The present invention aims to maximize the production of olefins constituting the polymers of plastics and / or tires and / or SRF via a steam cracking unit thanks to an upgrade in light pyrolysis gas, thereby enabling a significant increase in olefin yield and a reduction in environmental impact. [Background technology]

[0002] Plastics or recycled tires or other solid recovery fuels (SRFs) obtained from collection and sorting channels may be upgraded through a pyrolysis process. Pyrolysis involves heating the feedstock containing plastics and / or recycled tires and / or other SRFs in the absence of oxygen, with or without a catalyst, to form three main products: a hydrocarbon phase; which is liquid at ambient temperature and is also called pyrolysis oil; a light gas phase; also called pyrolysis gas; and a solid residue; also called char.

[0003] The liquid hydrocarbon phase—pyrolysis oil—is generally upgraded as a feedstock for steam cracking units, (re)forming olefins, which are constituent monomers of a given polymer. Pyrolysis oil often contains impurities in high concentrations and incompatible with steam cracking units or units located downstream of steam cracking units, particularly polymerization and selective hydrogenation methods often occur upstream of the steam cracking process. For example, a purification process is required, often involving at least one hydrogenation step.

[0004] Regarding the light gas phase obtained from pyrolysis, it is generally used (recycled) as fuel to provide the energy required for the pyrolysis reaction. Such methods are described, for example, in Patent Documents 1 to 6.

[0005] Another method for upgrading the light gas phase involves sending it directly to a steam cracking unit, possibly after pretreatment to remove H2S in particular, in order to increase the olefin yield. Such methods are described, for example, in Patent Documents 7-9. However, none of the documents describe the removal of CO and CO2 prior to introduction into the steam cracker.

[0006] However, the act of sending this light gas phase to the steam splitting unit faces the following two constraints: - Firstly, it is often necessary to purify this light gas phase (by desulfurization, dechlorination, and denitrification) and then send it to the steam cracking unit to maintain the stable and substantially unchanging operation of the steam cracking unit. While most impurities (chlorine, sulfur, nitrogen, metals, etc.) can be treated by the hydrotreatment (HDT) method upstream of the steam cracking process, CO and CO2 present in the light gas phase are also removed. On the one hand, the presence of CO has a negative (inhibitory) effect on the activity of catalysts used in units downstream of the steam cracker, and on the other hand, the presence of CO2 can cause the formation of ice crystals in the cold train of the steam cracker. - Secondly, it is advantageous to leave open the possibility of using at least a portion of the light gas phase obtained from pyrolysis to provide the energy required for the pyrolysis reaction, thereby reducing energy dependence and carbon emissions at the production site.

[0007] The present invention makes it possible to simultaneously address these two constraints, which is achieved by introducing a step of compressing the pyrolysis light gas phase to condense at least the C3+ hydrocarbons, and then separating them from the non-condensable gases (mainly H2, CO, CO2, C1, and C2). The condensed flow containing C3+ hydrocarbons is advantageously sent to a purification unit (HDT) to meet the specifications required for use as feedstock for a steam cracking unit. Alternatively, if the condensed flow rich in C3+ hydrocarbons is of satisfactory quality, it may be sent directly to the steam cracking unit, possibly together with another hydrocarbon feedstock.

[0008] The light products contained in the non-condensable gas are advantageously used, for example, as fuel to provide the energy required to operate the pyrolysis unit. In the context of the present invention, the conditions of the compression step can be adjusted to produce more or less non-condensable light products depending on the energy requirements of the pyrolysis unit. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2005 / 087897 [Patent Document 2] International Publication No. 2018 / 000050 [Patent Document 3] U.S. Patent Application Publication No. 2018 / 0010050 [Patent Document 4] U.S. Patent Application Publication No. 2018 / 0142164 [Patent Document 5] International Publication No. 2014 / 006273 [Patent Document 6] U.S. Patent Application Publication No. 2015 / 0080624 [Patent Document 7] International Publication No. 2016142808

Patent Document 8

Patent Document 9

Summary of the Invention

Means for Solving the Problems

[0010] (Summary of the Invention) More precisely, the present invention relates to a method for producing olefins from a feedstock containing plastic and / or tire and / or solid recovered fuel, the method comprising the following steps: (a) A step of pyrolyzing a feedstock containing plastic and / or tire and / or solid recovered fuel in a pyrolysis unit; recovering at least a first gaseous effluent containing a hydrocarbon mixture containing H2, CO, CO2 and C1-C6 hydrocarbons, and a first liquid effluent mainly containing C7+ hydrocarbons; (b) A step of compressing the first gaseous effluent obtained from step a), then cooling it, and then separating the compressed and cooled first gaseous effluent in a separation unit; obtaining a second liquid effluent mainly containing C3+ hydrocarbons and a residual second gaseous effluent enriched with H2, CO and CO2; (c) A step of introducing the second liquid effluent into a steam cracking unit in the presence of steam; producing olefins.

[0011] According to a variant, the first liquid effluent is introduced into the steam cracking unit of step c).

[0012] According to the modification, in step b), at least a portion of the first liquid effluent is introduced into the separation unit as a mixture with or not as a mixture of the compressed first gaseous effluent, the mixture is then separated to obtain an intermediate liquid effluent and the residual second gaseous effluent concentrated with H2, CO and CO2, the intermediate liquid effluent is then separated in a second separation unit to obtain the second liquid effluent mainly containing C3+ hydrocarbons and the residual third gaseous effluent concentrated with H2, CO and CO2.

[0013] According to the modification, the purification of the second liquid effluent obtained from step b) is performed in a purification unit upstream of the steam decomposition unit in step c).

[0014] According to the modification, the purification of the first liquid effluent obtained from step a) is performed in a purification unit upstream of the steam decomposition unit in step c).

[0015] According to the modification, step b) is performed such that, during one or more separations, the pressure is 0.5 to 2.5 relative MPa, preferably 1.0 to 1.5 relative MPa, and the temperature is 20 to 55°C, preferably 30 to 45°C.

[0016] According to the modification, the purification step includes a step of pre-treating the second liquid effluent obtained from step b) and / or the first liquid effluent obtained from step a), the pre-treatment step being carried out upstream of step c), and including an adsorption step and / or a filtration step and / or a centrifugation step and / or a decantation step and / or an electrostatic separation step and / or a washing step with an aqueous solution and / or a stripping step.

[0017] According to the modification, the purification process includes a hydrogenation process carried out in a hydrogenation reaction section, using at least one fixed-bed reactor having n catalyst beds, where n is an integer of 1 or more, each containing at least one hydrogenation catalyst, the hydrogenation reaction section is fed the optionally pre-treated second liquid effluent obtained from step b) and / or the optionally pre-treated first liquid effluent obtained from step a) and a hydrogen-containing gas stream, the average temperature when the hydrogenation reaction section is carried out is 150~430°C, the hydrogen partial pressure is 1.0~10.0 absolute MPa, and the spatiotemporal velocity is 0.1~10.0 h -1 This yields a purified second liquid effluent and / or a purified first liquid effluent.

[0018] According to the modification, the hydrogenation catalyst comprises a support selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof, and a hydrogenation-dehydrogenation functional element containing at least one element from Group VIII and at least one element from Group VIB, or at least one element from Group VIII.

[0019] According to the modification, following the hydrogenation process, a washing / separation process is carried out, and the optionally pre-treated, purified second liquid effluent and / or the optionally pre-treated, purified first liquid effluent and aqueous solution are fed to obtain at least a gaseous effluent, an aqueous effluent and the washed and purified second liquid effluent and / or the washed and purified first liquid effluent.

[0020] According to the modification, the optionally pre-treated and / or washed and purified second liquid effluent, and / or the optionally pre-treated and / or washed and purified first liquid effluent are subjected to at least one fractionation step in a fractionation unit to obtain at least one gas stream and at least one liquid stream of C3+ hydrocarbons.

[0021] According to the modification, the fractionation unit includes a depentane column from which liquid C3-C4 hydrocarbon streams and C5+ liquid hydrocarbon streams are extracted.

[0022] According to the modification, at least one of the liquid streams obtained from the fractionation step is sent, at least in part, to the steam decomposition unit in step c).

[0023] According to the modification, the steam decomposition step c) is carried out in at least one pyrolysis furnace at a temperature of 700-900°C and a relative pressure of 0.05-0.3 MPa in the presence of steam.

[0024] According to the modified version, in steam decomposition step c), the residence time of the hydrocarbon compound is 1.0 second or less, and the amount of water introduced in the form of steam is 0.3 to 3.0 kg per kg of hydrocarbon compound at the inlet of steam decomposition step c).

[0025] According to the variation, the supply materials consist of plastics and / or tires and / or solid recycled fuel.

[0026] For the remainder of this text, the term “pyrolysis oil” is understood to mean the oil produced as a result of the pyrolysis of plastics and / or tires and / or SRF, unless otherwise specified.

[0027] For the remainder of this text, the term “pyrolysis gas” is understood to mean the gases resulting from the pyrolysis of plastics and / or tires and / or SRF, unless otherwise specified.

[0028] According to the present invention, the expressions "of between ... and ..." and "between ... and ..." are synonymous, meaning that both upper and lower limits of the interval fall within the range of values ​​stated. If this is not the case, or if both limits do not fall within the range stated, such clarification is provided by the present invention.

[0029] In this explanation, the term "comprise" is synonymous with "include" and "contain" (meaning the same thing), and is inclusive or open-ended, not excluding other elements not mentioned. The term "comprise" is understood to encompass the exclusive and closed-ended term "consist."

[0030] In the spirit of the present invention, various parameter ranges for a given process, such as pressure ranges and temperature ranges, can be used individually or in combination. For example, for the purposes of the present invention, a suitable pressure range can be combined with a suitable temperature range.

[0031] Specific and / or preferred embodiments of the present invention are described below. They can be used separately or in combination, and there are no restrictions on the combinations, as long as the combinations are technically feasible.

[0032] The following groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor-in-chief DR. Lide, 81st edition, 2000-2001). For example, Group VIII (or Group VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9, and 10 of the new IUPAC classification.

[0033] The metal content is measured by X-ray fluorescence. [Modes for carrying out the invention]

[0034] (Detailed explanation) (Feed material) Plastic waste is generally a mixture of several polymers. The raw materials used in the methods according to the present invention may include, either alone or in mixtures, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polystyrene (at low and / or high densities). Furthermore, depending on the application, plastics may contain other compounds in addition to polymers, such as plasticizers, pigments, dyes, or residues of polymerization catalysts. Plastic waste may also contain small amounts of biomass, for example, from household waste.

[0035] Regarding tires, they are primarily composed of rubber for elastic properties (a mixture of cross-linked synthetic or natural rubber-type elastomers with the addition of silica, resin, sulfur, zinc oxide, carbon black, and other types of adjuvants) and textiles and metal fibers for reinforcement.

[0036] Solid recovered fuel (SRF), also known as refuse-derived fuel (RDF), is solid, non-toxic waste prepared for energy recovery, regardless of whether it originates from household waste and similar waste, waste from economic activities, or waste from construction and demolition. SRF is generally a mixture of any combustible waste, e.g., used tires, food by-products (fat, animal meal, etc.), viscose and wood waste, light parts resulting from shredders (e.g., used cars, light parts resulting from electrical and electronic equipment (WEEE)), household and commercial waste, and residues from the recycling of various types of waste, including, among other things, certain municipal waste, plastic waste, textiles, or wood. Plastic waste is commonly found in SRF.

[0037] The feedstock used in the method according to the present invention contains plastic and / or tire and / or SRF. Preferably, the feedstock consists of plastic and / or tire and / or SRF. In the case of a mixture of plastic, tire and / or SRF, this mixture may be prepared in any proportion.

[0038] (pyrolysis step a)) According to step a) of the method according to the present invention, a step of pyrolysis of a feed material containing plastics and / or tires and / or SRF is performed in a pyrolysis unit, and at least a first gaseous effluent, also called pyrolysis gas, containing a mixture of hydrocarbons including H2, CO, CO2 and C1-C6 hydrocarbons, and a first liquid effluent, also called pyrolysis oil, mainly containing C7+ hydrocarbons (i.e., the C7+ hydrocarbon content is 50% by weight or more relative to the mass of the liquid effluent).

[0039] The process of pyrolysis of feedstock containing plastics and / or tires and / or SRF can be carried out via thermal or catalytic pyrolysis treatment, or otherwise prepared by hydrothermal decomposition (pyrolysis in the presence of a catalyst and hydrogen).

[0040] The temperature at which the pyrolysis process is generally carried out is between 250°C and 750°C. The pyrolysis process can be carried out under more or less severe conditions.

[0041] The temperature during the low-severity pyrolysis process is 250°C to 450°C, preferably 275°C to 425°C, and particularly preferably 300°C to 400°C. The low-severity pyrolysis process produces pyrolysis oils rich in monoolefins and diolefins, as well as a considerable amount of aromatic compounds, which may contain chlorine compounds.

[0042] The temperature during the high-severity pyrolysis process is 450°C to 750°C, preferably 500°C to 700°C, and particularly preferably 550°C to 650°C. The high-severity pyrolysis process produces pyrolysis oil rich in aromatic compounds, which may contain chlorine compounds.

[0043] A pyrolysis unit may comprise one or more reactors configured to convert a feedstock into gaseous and liquid-phase products (for example, simultaneously). One or more reactors may contain one or more beds of inert material, including sand, zeolite, or a combination thereof, or a pyrolysis catalyst. Generally, the pyrolysis catalyst can transfer heat to the components subjected to the pyrolysis process in the pyrolysis unit.

[0044] The pyrolysis unit may comprise one or more pieces of equipment, such as one or more heated extruders, heated rotary kilns, heated tank-type reactors, dry-fired containers, closed heated surfaces through which the feed material flows along the walls, or other equipment providing a container or furnace or heated surface surrounded by a furnace.

[0045] In one or more embodiments of the pyrolysis unit, a purge gas is used in all or part of one or more pyrolysis steps to improve the decomposition of plastics, produce valuable products, and provide feed for steam decomposition, or a combination thereof. The purge gas may include hydrogen (H2), nitrogen (N2), steam, product gas, or a combination thereof.

[0046] The pyrolysis process makes it possible to produce at least two effluents: a first gaseous effluent, also called pyrolysis gas, containing a mixture of hydrocarbons including H2, CO, CO2, and C1-C6 hydrocarbons, and a first liquid effluent, also called pyrolysis oil, mainly containing C7+ hydrocarbons.

[0047] The first liquid effluent, which mainly contains C7+ hydrocarbons, is a pyrolysis oil, which is advantageously in liquid form at ambient temperature. The pyrolysis oil particularly contains a mixture of hydrocarbon compounds, especially paraffins (n-paraffins and isoparaffins), olefins (monoolefins and / or diolefins), naphthenes, and aromatic compounds. The boiling point of at least 80% by weight of these hydrocarbon compounds is preferably below 700°C, and more preferably below 550°C. In particular, depending on the origin of the feedstock processed by the pyrolysis unit, the pyrolysis oil may contain up to 70% by weight of paraffins, up to 90% by weight of naphthenes, up to 90% by weight of olefins, and up to 90% by weight of aromatic compounds, and it is understood that the sum of paraffins, naphthenes, olefins, and aromatic compounds is equal to 100% by weight of the hydrocarbon compounds.

[0048] The first liquid effluent mainly contains C7+ hydrocarbons. That is, the C7+ hydrocarbon content is 50% by weight or more relative to the mass of the first liquid effluent.

[0049] Pyrolytic oils may contain diolefins. The diolefin content is usually determined indirectly as the maleic anhydride value (MAV). This method is based on the Diels-Alder addition reaction between conjugated diolefins and maleic anhydride. A method for determining MAV is described by C. Lopez-Garcia et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57-68. MAV is expressed as the weight (mg) of maleic anhydride reacted with 1 g of sample (mg / g). MAV in pyrolytic oils varies between 5 and 100 mg / g.

[0050] The density of pyrolysis oil is measured at 15°C according to the ASTM D4052 method and is generally 0.75 g / cm³. 3 ~0.99 g / cm³ 3 Preferably 0.75 g / cm³ 3 ~0.95g / cm 3 That is the case.

[0051] Pyrolysis oil may also contain, and usually does contain, impurities such as metals, particularly iron, silicon, or halogen compounds, particularly chlorine compounds. These impurities may be present in high concentrations in the pyrolysis oil, for example, halogen elements (especially chlorine alone, but also bromine, fluorine, or iodine) may be present in amounts up to 500 ppm by weight, or even up to 700 ppm by weight, actually even up to 1000 ppm by weight, or even up to 5000 ppm by weight, with halogen elements generally present in amounts of 1 to 1000 ppm by weight, or 1 to 700 ppm by weight, or 1 to 500 ppm by weight. Pyrolytic oils may contain up to 500 ppm by weight of elemental chlorine, or more accurately up to 700 ppm by weight, actually up to 1,000 ppm by weight, and even up to 5,000 ppm by weight, contributed by chlorine compounds, with elemental chlorine generally present in amounts of 1 to 1,000 ppm by weight, or 1 to 700 ppm by weight, or more accurately, 1 to 500 ppm by weight.

[0052] This oil may contain up to 200 ppm by weight, and in fact up to 1500 ppm by weight, of metallic or metalloid elements, which are generally present in amounts of 1-200 ppm by weight or 1-1500 ppm by weight. Alkali metals, alkaline earth metals, transition metals, post-transition metals, and metalloids can be placed in the same category as metallic contaminants called metals, metallic elements, or metalloid elements. In particular, metals, metallic elements, or metalloid elements include silicon, iron, or both of these elements. Pyrolysis oil may contain up to 200 ppm by weight, or up to 1000 ppm by weight, of silicon, which are generally present in amounts of 1-200 ppm by weight, or 1-1000 ppm by weight, or 1-500 ppm by weight. Pyrolysis oil may contain up to 50 ppm by weight, or up to 100 ppm by weight, of iron, which are generally present in amounts of 1-50 ppm by weight or 1-100 ppm by weight. Pyrolytic oils may also contain phosphorus, sodium, calcium, potassium, and magnesium.

[0053] The pyrolysis oil may also contain other impurities, such as heteroatoms, particularly those contributed by sulfur compounds, oxygen compounds, and / or nitrogen compounds, the content of which is generally less than 40,000 ppm by weight of heteroatoms, preferably less than 15,500 ppm by weight of heteroatoms, and the heteroatoms are generally 1 to 40,000 ppm by weight or 1 to 15,500 ppm by weight.

[0054] Sulfur compounds are generally present at a concentration of less than 15,000 ppm by weight, preferably less than 10,000 ppm by weight, and are generally present at a concentration of 1 to 15,000 ppm by weight or 1 to 10,000 ppm by weight.

[0055] Oxygen compounds are generally present at a content of less than 15,000 ppm by weight, preferably less than 10,000 ppm by weight, and are generally present at 1 to 15,000 ppm by weight or 1 to 10,000 ppm by weight.

[0056] Nitrogen compounds are generally present at a content of less than 10,000 ppm by weight, preferably less than 5,000 ppm by weight, and are generally present at 1 to 10,000 ppm by weight or 1 to 5,000 ppm by weight.

[0057] The content of sulfur, oxygen, and / or nitrogen compounds often depends on the origin of the processed feedstock. Therefore, tire pyrolysis oil generally contains more heteroatoms, particularly sulfur compounds, than plastic pyrolysis oil.

[0058] Pyrolysis oil may also contain other impurities, such as heavy metals, including mercury, arsenic, zinc, and lead. For example, mercury or arsenic may be present in concentrations of up to 100 ppb by weight or up to 200 ppb by weight, while heavy metals are generally present in concentrations of 1 to 200 ppb by weight or 1 to 100 ppb by weight.

[0059] The first gaseous effluent obtained from pyrolysis, also called pyrolysis gas, contains a mixture of hydrocarbons including H2, CO, CO2, and C1-C6 hydrocarbons. It may also contain halogens (especially those in the form of chlorine compounds), water, sulfur, and nitrogen.

[0060] The first gaseous effluent generally contains hydrocarbons including C1-C6 hydrocarbons, and its content is at least 20% by volume, preferably at least 30% by volume, and particularly preferably at least 40% by volume, relative to the total volume of the first gaseous effluent.

[0061] The first gaseous effluent generally contains CO and CO2, with a content of at least 1 volume%, generally at least 2 volume%, and often at least 3 volume%, relative to the total volume of the first gaseous effluent.

[0062] The first gaseous effluent obtained from pyrolysis may contain halogens, particularly chlorine, depending on the properties of the pyrolyzed feedstock. The first gaseous effluent obtained from pyrolysis generally contains halogens, particularly chlorine, and its content is greater than 25 ppm by weight, generally greater than 50 ppm by weight, and often greater than 70 ppm by weight, relative to the total weight of the first gaseous effluent.

[0063] (Step b) of compressing, cooling, and separating the pyrolysis gas) In step b), the treatment of the first gaseous effluent according to the present invention is carried out to condense the C3+ hydrocarbons (also called condensates) contained in the first gaseous effluent into a liquid phase, while compounds H2, CO, CO2 and light C1-C2 hydrocarbons are separated into a non-condensable gas stream.

[0064] Specifically, the condensation of C3+ hydrocarbons in the pyrolysis gas makes it possible to increase the yield of olefins during the steam cracking process, while at the same time limiting the presence of CO and CO2 in the condensate, thereby limiting not only the deactivation of catalysts in the purification process if there is one, but also the deactivation of catalysts that may be used in units downstream of the steam cracker for processing ("polishing") the products formed by the steam cracker. This step b) therefore makes it possible to selectively extract upgradeable compounds (C3+ hydrocarbons, especially C3-C6 hydrocarbons) for the steam cracker.

[0065] The residual gas stream is non-condensable and can be used to provide the energy required for the operation of the pyrolysis process.

[0066] Therefore, during step b) of the method according to the present invention, the first gaseous effluent obtained from step a) is compressed and then cooled, and the compressed and cooled first gaseous effluent is then separated in a separation unit to obtain a second liquid effluent mainly containing C3+ hydrocarbons, particularly C3-C6 hydrocarbons, and a residual second gaseous effluent concentrated with H2, CO, and CO2.

[0067] Step b) is carried out such that during separation the relative pressure is 0.5 to 2.5 relative MPa (5 to 25 relative bar or barg) and the temperature is 20 to 55°C. Preferably, the pressure is 1.0 to 1.5 relative MPa and the temperature is 30 to 45°C, and more preferably 35 to 40°C.

[0068] The compression of the first gaseous effluent is generally carried out by at least one compressor. The cooling of the first gaseous effluent is generally carried out by a heat exchanger.

[0069] The separation can be advantageously carried out by any method known to those skilled in the art, such as a combination of one or more separators (one or more drums) and / or one or more stripping towers, which may be supplied with a stripping gas, for example, a hydrogen-rich gas stream. Preferably, the separation is carried out in the separator drums.

[0070] Step b) makes it possible to obtain a second liquid effluent mainly containing C3+ hydrocarbons and a residual second gaseous effluent containing H2, CO, CO2 and light C1-C2 hydrocarbons.

[0071] The term "second liquid spill containing mainly C3+ hydrocarbons" is understood to mean a liquid spill in which the C3+ hydrocarbon content is 50% by weight or more relative to the weight of the second liquid spill.

[0072] The second liquid effluent, which mainly contains C3+-C6 hydrocarbons, is low in CO and CO2. The expression "low in CO and CO2" is understood to mean that the CO and CO2 content is 5000 ppm by weight or less, preferably 3000 ppm by weight or less, relative to the weight of the second liquid effluent.

[0073] Specifically, following the series of compression, cooling, and separation in step b), CO and CO2 (and H2) are concentrated in the residual second gaseous effluent. This makes it possible to recover the second liquid effluent, in which the CO and CO2 content is acceptable for sending to steam decomposition step c) or an upstream purification step of steam decomposition step c).

[0074] According to another embodiment, at least a portion of the first liquid effluent obtained from the pyrolysis step a) can be introduced into the separation unit as a mixture with or without a mixture of the compressed first gaseous effluent. More specifically, the method according to the present invention may include step b), in which at least a portion of the first liquid effluent is introduced into the separation unit as a mixture with or without a mixture of the compressed first gaseous effluent, the mixture is then separated to obtain an intermediate liquid effluent and the residual second gaseous effluent concentrated with H2, CO and CO2, the intermediate liquid effluent is then separated in a second separation unit to obtain a second liquid effluent mainly containing C3+ hydrocarbons and a residual third gaseous effluent concentrated with H2, CO and CO2.

[0075] This embodiment allows for further extraction of organic components from the first gaseous effluent in the liquid phase obtained from the separation. The recovered components include C3 hydrocarbons (e.g., propane, propylene) and hydrocarbons with higher boiling points, but may also include C2 hydrocarbons (e.g., ethylene, ethane) as valuable petrochemical raw materials. Furthermore, this embodiment aims to maximize the recovery of organochlorine compounds and other impurities, clean the first gaseous effluent, and concentrate the impurities in the liquid phase for further purification in the refining process. By pressurizing and contacting the first gaseous effluent with the first liquid effluent, the partial pressure of the vapor in liquid form from the separation is reduced, thus entraining the heaviest organic components of the vapor phase of the first gaseous effluent into the liquid phase, creating a "sponge" effect. Several options exist for sending all or part of the first liquid effluent to the separation: - The first liquid effluent obtained from step a) is sent directly to the separation unit. - The first liquid effluent obtained from step a) is mixed with the compressed first gaseous effluent either upstream or downstream of the cooling process, and the mixture is sent to a separation unit.

[0076] In this embodiment, the separation of the mixture can be advantageously carried out by any method known to those skilled in the art, such as a separator drum or an adsorbent column, in which the first liquid effluent is introduced at its top and the first gaseous effluent is introduced at its bottom.

[0077] The residual second gaseous effluent, which is the gas phase obtained from the separation of the mixture, has a lower impurity content than the first gaseous effluent, thus making it easier to use as fuel for either a pyrolysis unit or an external application, or as a feedstock for a steam cracker.

[0078] The intermediate liquid effluent, which is the liquid recovered from the separation of the mixture, is then processed in a second separation unit to produce the second liquid effluent and a residual third gaseous effluent. This separation step allows for further removal of lighter components, such as H2, CO, and / or CO2, from the intermediate liquid effluent to a level generally up to 1000 ppm, often less than 100 ppm, but preferably less than 10 ppm by weight. The removal of these components prevents them from finding a way to more easily enter either the steam decomposition unit or the purification unit.

[0079] The separation of the intermediate liquid effluent can be advantageously carried out by any method known to those skilled in the art, for example, by distillation (e.g., distillation using a tray distillation column or a packed distillation column), a combination of one or more separator drums, a pervaporation membrane, or any combination thereof.

[0080] The separation of the intermediate liquid effluent can be carried out within the same pressure and temperature range as the separation of the mixture. The pressure and temperature conditions may be the same or different. If a distillation column is used as the second separation unit, the separation temperature can be 80-150°C at the bottom of the column, and the pressure can be 1-1.5 MPa.

[0081] The residual third gaseous effluent is concentrated with light components, which may include CO, CO2, and methane, but also include certain light hydrocarbon components, particularly ethylene and heavier hydrocarbon compounds. The residual third gaseous effluent can be recycled upstream of compression or cooling and mixed with the first gaseous effluent, and some of the light hydrocarbon components can be recovered into the liquid phase from the separation of the mixture. In some cases, the residual third gaseous effluent can also be mixed with residual second gaseous effluent or fuel for a pyrolysis unit, and its energy contents can be used as fuel for either the pyrolysis unit or an external application.

[0082] (Steam decomposition process c)) According to step c) of the method according to the present invention, the second liquid effluent (condensate) is introduced into a steam decomposition unit in the presence of water vapor to obtain an olefin.

[0083] Advantageously, the first liquid effluent (pyrolysis oil), which mainly contains C7+ hydrocarbons, is also introduced into the steam decomposition unit of step c) either as a mixture with the second liquid effluent (condensate) or not as a mixture.

[0084] The aforementioned second liquid effluent (condensate) can account for 0.5% to 10% by weight relative to the total weight of the feedstock mixture introduced into the steam decomposition process.

[0085] The steam decomposition step c) is advantageously carried out in the presence of steam in at least one pyrolysis furnace, at a temperature of 700 to 900°C, preferably 750 to 850°C, and at a pressure of 0.05 to 0.3 relative MPa. The residence period of the hydrocarbon compound is generally 1.0 second (also expressed as s), preferably 0.1 to 0.5 s. Advantageously, the steam is introduced upstream of the steam decomposition step c). The amount of water introduced in the form of steam is advantageously 0.3 to 3.0 kg of water per kg of the hydrocarbon compound at the inlet of the steam decomposition step.

[0086] The steam cracking process can be carried out in multiple parallel pyrolysis furnaces, with operating conditions adapted to various flows supplied to the steam cracking process and the number of tube decoking cycles controlled. A furnace may include one or multiple tubes arranged in parallel. A furnace may also represent a group of furnaces operating in parallel. For example, a furnace may be dedicated to cracking an intermediate distillate fraction.

[0087] Evaporates from various steam cracking furnaces are generally separated for the purpose of recombining them into a single effluent. The steam cracking process includes the steam cracking furnace, but is understood to also include related auxiliary processes known to those skilled in the art. These auxiliary processes may include, among others, heat exchangers, towers and catalytic reactors, and recycling to the furnace. Towers generally allow for the fractionation of the effluent. This fractionation is carried out for the purpose of recovering at least a light fraction containing hydrogen and compounds having 2-5 carbon atoms, and a fraction containing pyrolysis gasoline, and possibly a heavier fraction. Towers allow for the separation of various components of the fractionated light fraction, recovering at least an ethylene-rich fraction (C2 fraction) and a propylene-rich fraction (C3 fraction), and possibly a butene-rich fraction (C4 fraction). Catalytic reactors particularly allow for the hydrogenation of the C2, C3, and even C4 fractions, as well as the pyrolysis gasoline. Saturated compounds, particularly those having 2 to 4 carbon atoms, are advantageously recycled into steam cracking furnaces, increasing the overall yield of olefins.

[0088] This steam decomposition step c) makes it possible to obtain at least one effluent containing olefins containing 2, 3, and / or 4 carbon atoms (i.e., C2, C3, and / or C4 olefins) in a satisfactory content, in particular, at a content of 30% by weight or more of the total weight of olefins containing 2, 3, and 4 carbon atoms relative to the weight of the steam decomposition effluent under consideration. The C2, C3, and C4 olefins can then be advantageously used as polyolefin monomers.

[0089] According to one embodiment, if the second liquid effluent (condensate) and / or the first liquid effluent (pyrolysis oil) do not meet the specifications (in particular, the chlorine-related specifications) at the inlet of the steam decomposition unit, these specifications can be achieved by dilution at the inlet of the steam decomposition unit with a feedstock that is chlorine-free or contains very small amounts of chlorine, such as petroleum feedstock. The petroleum feedstock is preferably selected from naphtha, kerosene, gas oil, or a mixture of such feedstocks.

[0090] According to another embodiment, the second liquid effluent (condensate) and / or the first liquid effluent (pyrolysis oil) that do not meet the specifications (particularly the chlorine specifications) at the inlet of the steam decomposition unit may undergo at least one purification step before being introduced into steam decomposition step c).

[0091] (One or more purification steps upstream of the steam cracking process (optional)) The second liquid effluent (condensate) obtained from step b) may contain impurities at excessively high concentrations compared to the specifications of the steam decomposition unit. These impurities include, in particular, halogen compounds, especially chlorine-based compounds, as well as diolefins, olefins, metals, especially iron and silicon, and other heteroatoms, such as sulfur, oxygen, and nitrogen.

[0092] Steam decomposition units require very high feed purity, particularly low content of chlorine, diolefins, olefins, and metals and sulfur. The chlorine content specification at the inlet of the steam decomposition unit is typically a maximum of 3 ppm by weight, preferably a maximum of 1 ppm by weight.

[0093] The second liquid effluent (condensate) obtained from step b) may therefore undergo at least one purification process in a purification unit upstream of the steam decomposition unit to achieve the specifications required for steam decomposition step c).

[0094] The same applies to the first liquid effluent (pyrolysis oil) obtained from step a), which mainly contains C7+ hydrocarbons, and which may also contain, in addition to halogen compounds, especially chlorine-based compounds, diolefins, olefins, metals, especially iron and silicon, or other heteroatoms, such as sulfur, oxygen and nitrogen, as well as insoluble substances.

[0095] The first liquid effluent (pyrolysis oil) obtained from step a) may therefore undergo at least one refining process in a refining unit upstream of the steam decomposition unit to achieve the specifications required for steam decomposition step c).

[0096] The purification process may include a hydrogenation process, which may be preceded by a pretreatment and / or may be followed by a washing / separation process.

[0097] According to the modification, only the second liquid effluent undergoes at least one purification step in the purification unit upstream of the steam decomposition unit c).

[0098] According to another modification, only the first liquid effluent undergoes at least one purification step in the purification unit upstream of the steam decomposition unit c).

[0099] In another variation, this variation is preferable, in which the second liquid effluent and the first liquid effluent undergo at least one refining step in a refining unit upstream of the steam decomposition unit, preferably in the same refining unit. Thus, the second liquid effluent (condensate) can be sent to a hydrogenation step, either as a mixture with or separately from the first liquid effluent (pyrolysis oil), followed by a washing / separation step.

[0100] In another variation, the second liquid effluent and the first liquid effluent may undergo several refining steps, some individually and some together. Thus, the first liquid effluent (pyrolysis oil) may undergo, for example, pretreatment and then, together with the second liquid effluent (condensate), be sent to a hydrotreatment step followed by a washing / separation step, or otherwise directly to a steam cracking step c).

[0101] (Preprocessing (optional)) One route for removing impurities contained in the second effluent and / or the first liquid effluent is to perform pretreatment, which is generally performed upstream of the hydrogenation step, if there is a hydrogenation step after the pyrolysis step.

[0102] According to the modification, this optional pretreatment step makes it possible to reduce the amount of contaminants and solid particles. In particular, this optional pretreatment step makes it possible to remove sediments that may be formed as a result of the unstable nature of the pyrolysis oil and / or compatibility issues between two different feedstocks.

[0103] The optional pretreatment steps can be carried out by any method known to those skilled in the art that enables a reduction in the amount of contaminants. This may include, in particular, adsorption steps and / or filtration steps and / or centrifugation steps and / or decantation steps and / or electrostatic separation steps and / or washing with aqueous solution steps and / or gas stripping steps.

[0104] The temperature at which the optional pretreatment step is advantageously carried out is 20 to 400°C, preferably 40 to 350°C, and the pressure at that time is 0.15 to 10.0 absolute MPa, preferably 0.2 to 7.0 absolute MPa.

[0105] According to the modification, the optional pretreatment step is carried out in an adsorption section operated in the presence of at least one adsorbent. The adsorbent can be selected from zeolite, activated carbon, clay, silica, or alumina. Advantageously, the adsorbent contains less than 1% by weight of metallic elements, and preferably lacks metallic elements. The term “metallic elements in the adsorbent” should be understood to mean elements from groups 6-10 of the periodic table (new IUPAC classification).

[0106] According to another variation, the optional pretreatment step is carried out in a section for washing with an aqueous solution, such as water, or an acidic or basic solution. This washing section may include equipment that allows contact between the pyrolysis oil and / or condensate and the aqueous solution and separates the phases to obtain, on the one hand, the pretreated feedstock and on the other hand, an aqueous solution containing impurities. These devices may include, for example, a stirred reactor, a settler, a mixer-settler, and / or a parallel or countercurrent washing column.

[0107] In another variation, the optional pretreatment step is carried out by filtration. The filtration step makes it possible to remove inorganic solids, sediments and / or particulate matter contained in the pyrolysis oil and / or condensate, in particular metals, metal oxides and metal chlorides. Filters are commonly used, with pore sizes (e.g., diameter or equivalent diameter) of less than 25 μm, preferably 10 μm or less, and more preferably 5 μm or less. A series of filters with different pore sizes may be used, in particular a series of filters with pore sizes decreasing in the direction of flow of the feed material. These filter materials are well known for industrial applications. Cartridge filters or self-cleaning filters are suitable, for example.

[0108] According to another variation, the optional pretreatment step is carried out by centrifugation, decantation, or electrostatic separation.

[0109] According to another variation, the optional pretreatment step is carried out by gas stripping, thereby reducing the oxygen content in the feedstock. Gas extraction can remove oxygen (O2) that may be dissolved in the pyrolysis oil and / or condensate, thereby reducing the possibility of free radical formation resulting in polymerization in downstream processes. The method generally involves contacting the pyrolysis oil and / or condensate with an extraction gas (e.g., H2, N2, or a mixture thereof), thereby transferring at least some of the dissolved oxygen in the feedstock to the extraction gas, followed by the separation of the extraction gas from the pyrolysis oil and / or condensate. Any dissolved H2 remaining in the pyrolysis oil and / or condensate after the gas extraction step is not a problem, assuming that a hydrogenation step is generally carried out downstream.

[0110] The optional preprocessing steps generally include one or more, preferably more of, of the above processes.

[0111] The aforementioned optional pretreatment step makes it possible to obtain the pretreated second effluent and / or the pretreated first liquid effluent, which can then be fed to a hydrogenation step or, in some cases, to a steam decomposition step c) after a fractionation step.

[0112] (Hydrogenation process (optional)) Another route for removing impurities contained in the second liquid effluent and / or the first liquid effluent is to carry out a hydrogenation process in the presence of a catalyst.

[0113] Therefore, the purification process can include a hydrogenation process carried out in the hydrogenation reaction section, using at least one fixed-bed reactor having n catalyst beds, where n is an integer of 1 or more, each containing at least one hydrogenation catalyst. The hydrogenation reaction section feeds the optionally pretreated second liquid effluent obtained from step b) and / or the optionally pretreated first liquid effluent obtained from step a) and an air stream containing hydrogen. The average temperature during the hydrogenation reaction is 150 - 430 °C, the hydrogen partial pressure is 1.0 - 10.0 absolute MPa, and the space velocity is 0.1 - 10.0 h -1 to obtain a purified second liquid effluent and / or a purified first liquid effluent.

[0114] Advantageously, the hydrogenation process performs hydrogenation reactions well-known to those skilled in the art, more particularly hydrogenation reactions such as hydrodemetallization, hydrogenation of aromatic compounds, hydrodesulfurization, and hydrodenitrogenation, and also performs hydrogenation of olefins (monoolefins and diolefins) and hydrogenation of halogen compounds (particularly chlorine compounds).

[0115] The average hydrogenation temperature (or the following WABT) when the hydrogenation reaction section is advantageously carried out is 150 - 430 °C, preferably 280 - 380 °C, the hydrogen partial pressure at that time is 1.0 - 10.0 absolute MPa, and the space velocity (HSV) at that time is 0.1 - 10.0 h -1 , preferably 0.1 - 5.0 h -1 , preferentially 0.2 - 2.0 h -1 , suitably 0.2 - 1 h -1 is. The hydrogen coverage rate is advantageously 50 - 1000 Nm of hydrogen per cubic meter (m 3 ) of the feedstock fed to the hydrogenation process, preferably 50 - 500 Nm of hydrogen per cubic meter (m 3 ) of the feedstock, suitably 100 - 300 Nm of hydrogen per cubic meter (m 3 ) of the feedstock, 3 preferably 100 - 300 Nm of hydrogen per cubic meter (m 3 ) of the feedstock, 3 is.

[0116] ​​ The “average temperature” of the reaction section corresponds to the weight-average bed temperature (WABT), which is well known to those skilled in the art. The average temperature is advantageously determined depending on the catalyst system, equipment, and their configurations used. The average temperature (or WABT) is calculated as follows:

[0117]

number

[0118] In the formula, T inlet : The temperature of the effluent at the inlet of the reaction section, and T outlet : The temperature of the effluent at the outlet of the reaction section.

[0119] The space-spatiotemporal velocity (HSV) is defined here as the ratio of the hourly volumetric flow rate of any selected pre-treated feedstock to the volume of one or more catalysts.

[0120] Hydrogen coverage is defined as the ratio of the volumetric flow rate of hydrogen under standard temperature and pressure conditions to the volumetric flow rate of an optional pre-treated feedstock at 15°C, without taking into account any recycled portions (volume of feedstock (m³) 3 ) Standard H2 m per unit 3 (Nm 3 It is described as follows).

[0121] Preferably, the method according to the present invention includes a hydrogenation step carried out in a hydrogenation reaction section, using at least one fixed-bed reactor having n catalyst beds, where n is an integer of 1 or more, preferably 1 to 10, and more preferably 2 to 5, each containing at least one hydrogenation catalyst.

[0122] The hydrogenation reaction section is advantageously supplied with the second liquid effluent obtained from step b) and / or the first liquid effluent obtained from step a), along with a hydrogen-containing gaseous flow, to at least the first catalyst bed of the first reactor in operation. Injection of at least a portion of the feedstock and / or at least a portion of the hydrogen between the various catalyst beds is also possible.

[0123] A hydrogenation reaction section using at least one fixed-bed reactor can be operated by downward or upward flow of gas and liquid.

[0124] The hydrogen-containing gaseous stream is supplied to the hydrogenation reaction section and can consist of supply hydrogen and / or recycled hydrogen. The hydrogen-containing gaseous stream may originate from fossil or renewable sources, for example, from the gasification of plastic waste or produced by electrolysis.

[0125] Preferably, an additional gas stream containing hydrogen is advantageously introduced at the inlet of each reactor, particularly at reactors operating in series, and / or at the inlet of each catalyst bed, starting from the second catalyst bed of the reaction section. These additional gas streams are also called cooling streams. They make it possible to control the temperature in the reactor, where the reaction being carried out is generally highly exothermic.

[0126] Preferably, the hydrogenation process may use at least one guard bed upstream of one or more hydrogenation catalysts. This guard bed contains an adsorbent of the type alumina, silica, silica-alumina, zeolite, and / or activated carbon, and optionally contains metals from Group VIB and / or Group VIII. A series of guard beds having particles of different diameters may be used, in particular a series of guard beds having a diameter that decreases in the direction of the flow of the feedstock (also referred to as "grading").

[0127] Advantageously, the hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrogenation dehydrogenation functional product.

[0128] According to this modification, the hydrogenation dehydrogenation functional product particularly comprises at least one element from Group VIII and at least one element from Group VIB, wherein the at least one element from Group VIII is preferably selected from nickel and cobalt, and the at least one element from Group VIB is preferably selected from molybdenum and tungsten. According to this modification, the total content expressed as oxides of metal elements from Group VIB and Group VIII is preferably 1% to 40% by weight, and preferably 5% to 30% by weight, relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO, respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3, respectively. The weight ratio expressed as the metal content of one or more metals from Group VIB relative to one or more metals from Group VIII is preferably 1 to 20, and more preferably 2 to 10.

[0129] According to this modification, the hydrogenation catalyst included in the reaction section of the hydrogenation process contains, for example, 0.5% to 12% by weight of nickel, preferably 0.9% to 10% by weight of nickel (expressed as nickel oxide NiO relative to the weight of the catalyst), and 1% to 30% by weight of molybdenum, preferably 3% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO3 relative to the weight of the catalyst), preferably on a mineral support, preferably on an alumina support.

[0130] According to another modification, the hydrogenation-dehydrogenating functional product contains, and preferably consists of, at least one element from Group VIII, preferably nickel. According to this modification, the nickel oxide content is preferably 1% to 50% by weight, and preferably 10% to 30% by weight, relative to the weight of the catalyst. This type of catalyst is preferably used in its reduced form, preferably on a mineral support, and preferably on an alumina support.

[0131] According to another aspect of the present invention, the hydrogenation catalyst described above further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such catalysts are often denoted by the term “additivated catalyst.” Generally, the organic compounds are selected from compounds containing one or more chemical functional groups selected from the groups of carboxylic acids, alcohols, thiols, thioethers, sulfones, sulfoxides, ethers, aldehydes, ketones, esters, carbonates, amines, nitriles, imides, oximes, ureas, and amides, or compounds containing furan rings or sugars.

[0132] The support for the hydrogenation catalyst is preferably selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof. The support may include dopant compounds, in particular boron oxides, in particular boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide, and mixtures thereof. Preferably, the hydrogenation catalyst comprises an alumina support and is optionally doped with phosphorus and boron. If phosphorus pentoxide (P2O5) is present, its concentration is less than 10% by weight relative to the weight of alumina and favorably at least 0.001% by weight relative to the total weight of alumina. If boron oxide (B2O3) is present, its concentration is less than 10% by weight relative to the weight of alumina and favorably at least 0.001% by weight relative to the total weight of alumina. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

[0133] The hydrogenation catalyst is, for example, in the form of an extruded product or beads.

[0134] The preparation of catalysts for hydrogenation processes is known and generally involves impregnation of a support with metals from Group VIII and, if present, from Group VIB, and optionally phosphorus and / or boron, followed by drying, and then optionally calcination. The catalyst may also be a catalyst used in its reducing form, and therefore a reduction step may be included in its preparation.

[0135] Prior to use in the process of this method, the catalyst is generally subjected to sulfidation to form active species. Depending on the sulfur compound content in the initial feedstock to be treated, a stream containing a sulfidating agent can be injected upstream of an optional pretreatment step or upstream of a hydrogenation step, preferably upstream of a hydrogenation step, to ensure a sufficient amount of sulfur to form the active species (in the form of sulfides) of the catalyst. This activation or sulfidation step is carried out by methods well known to those skilled in the art, advantageously under a sulfo-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. The sulfidating agent is preferably H2S gas, elemental sulfur, CS2, thiols, sulfides and / or polysulfides, a hydrocarbon fraction with a boiling point below 400°C containing sulfur compounds, or any other sulfur-containing compound used for activating the hydrocarbon feedstock with respect to sulfiding the catalyst. The sulfur-containing compound is advantageously selected from alkyl disulfides, e.g., dimethyl disulfide (DMDS), alkyl sulfides, e.g., dimethyl sulfide, thiols, e.g., n-butylthiol (or 1-butanethiol), and tert-nonyl polysulfide type polysulfide compounds. The catalyst may also be sulfurized by sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfurized in situ in the presence of a sulfidating agent and a hydrocarbon feedstock. More preferably, the catalyst is sulfurized in situ in the presence of a feedstock to which dimethyl disulfide has been added. The sulfidating agent can be injected continuously.

[0136] According to the modification, the hydrogenated second liquid spill and / or first liquid spill can be supplemented with feedstock obtained from conventional petroleum feedstock or biomass conversion, which is then co-treated in the pretreatment and / or hydrogenation process.

[0137] Conventional petroleum supply raw materials can, advantageously, be fractions or mixtures of fractions of the type naphtha or gas oil.

[0138] The feedstock obtained from biomass conversion may be advantageously selected from vegetable oils, oils or algal oils from algae, fish oils, waste food oils, and fats of plant or animal origin, or mixtures of such feedstocks. The vegetable oil may be advantageously crude or fully or partially refined and obtained from plants selected from rapeseed, sunflower, soybean, palm, olive, coconut, coconut kernel, castor oil plant, cotton, peanut oil, linseed oil, and seaweed oil, and includes, for example, all oils obtained from genetically modified or hybridized sunflower or rapeseed, but this list is not limited. The animal fat may be advantageously selected from fats and fats consisting of residues from the food industry or obtained from the catering industry. Frying oils, various animal oils, such as fish oil, animal fat, or lard may also be used. The feedstock obtained from biomass conversion may, advantageously, be selected from methyl esters of fatty acids of plant and / or animal origin, or also from methyl esters of fatty acids of waste food vegetable oils.

[0139] The feedstock obtained from biomass conversion may also be selected from feedstock originating from thermal or catalytic biomass conversion methods, such as oils derived from biomass, particularly lignocellulosic biomass, by various liquefaction methods, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to materials derived from organisms that were recently alive, and includes plants, animals, and their by-products. The term "lignocellulosic biomass" refers to biomass derived from plants or their by-products. Lignocellulosic biomass consists of carbohydrate polymers (cellulose, hemicellulose) and aromatic polymers (lignin).

[0140] The raw materials obtained from biomass conversion can, advantageously, also be selected from raw materials obtained from the paper industry.

[0141] After the hydrogenation process, purified second liquid effluent and / or purified first liquid effluent are obtained.

[0142] (Washing / separation process) According to the modification, a washing / separation step can be performed after the hydrogenation step, and the optionally pre-treated, purified second liquid effluent and / or the optionally pre-treated, purified first liquid effluent and an aqueous solution are fed to obtain a gaseous effluent, an aqueous effluent, and at least the washed and purified second liquid effluent and / or the washed and purified first liquid effluent.

[0143] The hydrogenation of chlorine compounds in the form of HCl, in particular, is released during the hydrogenation process and subsequently dissolved in water. The reaction between chloride ions, which are generated during the hydrogenation process in the form of NH3 by the hydrogenation of nitrogen compounds and / or provided by the injection of amines, and subsequently dissolved in water, produces ammonium chloride salts. This washing / separation step makes it possible to remove such ammonium chloride salts, in particular, thus limiting the risk of clogging due to the precipitation of ammonium chloride salts, particularly in the transfer lines and / or sections and / or transfer lines to the steam decomposer of the method of the present invention. Hydrochloric acid is formed by the reaction of hydrogen ions with halide ions, which are released during the hydrogenation process by the hydrogenation of halogen compounds and dissolved in aqueous solution. This step also makes it possible to remove such hydrochloric acid. If H2S is present in the hydrogenated effluent obtained from the hydrogenation process, the washing / separation step also makes it possible to remove ammonium sulfide ((NH4)2S) salts, which are produced by the reaction between H2S obtained from the hydrogenation desulfurization of sulfur compounds and NH3, by dissolving them in aqueous solution.

[0144] The temperature during the washing / separation process is advantageously 50–450°C, preferredly 100–440°C, and preferably 200–420°C. Operating within this temperature range (and thus avoiding excessive cooling of the hydrogenation effluent) is important in mitigating the risk of line clogging due to ammonium chloride salt precipitation. Advantageously, the pressure during the washing / separation process is close to the pressure used in the hydrogenation process, preferably 1.0–10.0 absolute MPa, to facilitate hydrogen recycling.

[0145] The aqueous solution may be water. It can also be a basic aqueous solution (for example, by adding NaOH). The use of a basic solution makes it possible to neutralize hydrogen halides and any dissolved salts.

[0146] The washing / separation process can, advantageously, be carried out in common or separate washing and separation equipment, which is well known (separator drums, pumps, heat exchangers, washing columns, etc., which can be operated at various pressures and temperatures).

[0147] Advantageously, the washing / separation step includes the injection of an aqueous solution, preferably water, into the hydrogenated effluent upstream of the washing / separation section to dissolve at least some, preferably all, of the hydrogen halides (particularly HCl) and any salts present.

[0148] In one optional embodiment of the present invention, the washing / separation step comprises injecting an aqueous solution into the hydrogenated effluent and is followed by a washing / separation section, which advantageously includes a separation phase for obtaining at least one aqueous effluent loaded with hydrogen halides (particularly HCl) and any dissolved salt present, a washed hydrogenated effluent, and a partially washed gaseous effluent. The aqueous effluent and the washed hydrogenated effluent can then be separated in a decant vessel to obtain the washed hydrogenated effluent and the aqueous effluent. The partially washed gaseous effluent can concurrently be introduced into a washing column, where it flows opposite an aqueous stream, preferably an aqueous stream of the same nature as the aqueous solution injected into the hydrogenated effluent, thereby removing at least some, preferably all, of the hydrochloric acid contained in the partially washed gaseous effluent, thus making it possible to obtain the gaseous effluent, preferably essentially hydrogen-containing, and an acidic aqueous stream. The aqueous effluent obtained from the decanting container may, optionally, be mixed with the acidic aqueous stream, and possibly as a mixture with the acidic aqueous stream, in a water recycling circuit to feed the aqueous solution upstream of the wash / separation section and / or the aqueous stream in the wash column to the wash / separation process. The water recycling circuit may include a bleed that allows for the discharge of feedwater and / or basic solution and / or impurities.

[0149] According to one embodiment, depending on the content of chlorine compounds in the second liquid effluent and / or the first liquid effluent, a stream containing nitrogen compounds, such as ammonia or amines, such as monoethanolamine, diethanolamine and / or monodiethanolamine, can be injected upstream of the hydrogenation process to ensure a sufficient amount of ammonium ions to combine with the chloride ions formed during the hydrogenation process in the form of ammonium chloride salts, thereby limiting the formation of hydrochloric acid and thus limiting corrosion downstream of the separation section.

[0150] The gaseous effluent obtained at the end of the washing / separation process is advantageously hydrogen-containing, preferably at least 60% by volume, and more preferably at least 70% by volume. The gaseous effluent obtained at the end of the washing / separation process is chlorine-free, generally containing chlorine at a concentration of less than 3 ppm by weight, which allows it to be sent to a refinement unit requiring hydrogen. According to one embodiment, the gaseous effluent can be recycled, at least partially, to a hydrogenation process, and the recycling system may include a refinement section (e.g., for the adsorption of heavy metals, mercury).

[0151] The aqueous effluent obtained at the end of the washing / separation process preferably contains ammonium salts and / or hydrochloric acid.

[0152] The washed and purified second liquid effluent and / or a portion of the washed and purified first liquid effluent can be recycled upstream of the hydrogenation process, thereby allowing for dilution of impurities and, on the other hand, control of the temperature in the hydrogenation process, where the reactions involved may be highly exothermic. By diluting impurities, it is possible to limit undesirable reactions, such as the polymerization of diolefins (formation of gum-like substances and / or coke).

[0153] According to another embodiment, the embodiment is preferred, wherein the washed and purified second liquid effluent and / or the washed and purified first liquid effluent are partially, preferably completely, directly sent to the inlet of the steam decomposition unit.

[0154] (Fractionalization process (optional)) According to one embodiment, the optionally pretreated and / or washed and purified second liquid effluent, and / or the optionally pretreated and / or washed and purified first liquid effluent are subjected to at least one fractionation step in a fractionation unit upstream of the steam cracking step to obtain at least one gas stream, at least one liquid stream of C3+ hydrocarbons, such as naphtha fraction, and at least one intermediate distillate fraction.

[0155] The term "naphtha fraction" is understood to refer to a hydrocarbon fraction containing compounds whose boiling points are generally below 175°C, particularly between 80°C and 175°C.

[0156] The term "intermediate distillate fraction" is understood to refer to a hydrocarbon fraction containing compounds whose boiling point is generally above 175°C. Heavy fractions may include intermediate distillates, such as diesel and / or kerosene fractions, which may also contain heavier compounds.

[0157] Those skilled in the art will adjust the cut point in the stripping and / or distillation operation according to the intended use or application of the fraction obtained from the fractionation process. For example, it may be necessary to adjust the endpoint of the naphtha fraction to 150, 175, or 200°C, or even 250°C.

[0158] The fractionation process makes it possible to remove gases dissolved in the liquid hydrocarbon effluent, such as ammonia, hydrogen sulfide, and light C1-C2 hydrocarbons.

[0159] The pressure during the fractionation process is advantageously 1.0 absolute MPa or less, preferably 0.1 to 1.0 absolute MPa.

[0160] According to one embodiment, the fractionation process can be carried out in a section that advantageously includes at least one stripping column having a reflux circuit with a reflux drum. The optionally pretreated and / or washed and purified second liquid effluent and / or the optionally pretreated and / or washed and purified first liquid effluent may optionally be heated before entering the stripping column. Thus, the lightest compounds are encombined at the top of the column and enter the reflux circuit with a reflux drum, where gas / liquid separation takes place. The gas phase containing light C1-C2 hydrocarbons is withdrawn from the reflux drum as a gas stream. The naphtha fraction is advantageously withdrawn from the reflux drum as a liquid stream. The intermediate distillate fraction is advantageously withdrawn from the bottom of the stripping column.

[0161] According to another embodiment, the fractionation step may be carried out in a section comprising one or more separator drums. Advantageously, at least one "low-pressure, low-temperature" separator drum is used to remove gases dissolved in the optionally pre-treated and / or washed and purified second liquid effluent and / or the optionally pre-treated and / or washed and purified first liquid effluent.

[0162] According to other embodiments, the fractionation step may use only a stripping column and a subsequent distillation column or distillation column.

[0163] In yet another embodiment, the fractionation process may be carried out in a depentane column, from which, in addition to the gaseous flow, the C3-C4 liquid flow and the C5+ liquid flow are extracted.

[0164] At least one of the liquid streams obtained by the fractionation process (naphtha fraction, intermediate distillate fraction, C3-C4 liquid stream, or C5+ liquid stream) can be sent in whole or in part to a steam cracking process, at which point the olefin may be (re)formed and participate in polymer formation.

[0165] In another variation, a portion of the liquid C3-C4 flow may be sent to the steam decomposition process, while another portion may be used as fuel gas to provide some of the energy required to operate, for example, a pyrolysis unit. By separating the liquid C3-C4 flow that can be sent to the steam decomposition or pyrolysis unit, it is thus possible to adjust the energy requirements of the pyrolysis unit.

[0166] One or more fractions of gas or liquid obtained from the fractionation step can be subjected to one or more additional purification steps, such as washing with an amine, water, or sodium hydroxide.

[0167] Alternatively, a portion of at least one of the liquid streams obtained by the fractionation process may be recycled to at least one of the processes of the present method (e.g., pretreatment or hydrogenation) and / or sent to a unit for storing fuels obtained from conventional petroleum feedstocks, such as a unit for storing naphtha or a unit for storing intermediate distillates.

[0168] Advantageously, one or more purification steps enable the hydrogenation of at least 80%, preferably all, of the olefins (monoolefins and diolefins), as well as at least partial conversion of other impurities present in the feedstock, such as aromatic compounds, metallic compounds, sulfur compounds, nitrogen compounds, halogen compounds (especially chlorine compounds), and oxygen compounds.

[0169] Preferably, the nitrogen content is less than 10 ppm by weight at the outlet of the purification process.

[0170] Preferably, the sulfur content is less than 10 ppm by weight at the outlet of the refining process.

[0171] Preferably, the oxygen content is less than 10 ppm by weight at the outlet of the purification process.

[0172] Preferably, the metal content is less than 10 ppm by weight, preferably less than 2 ppm by weight, at the outlet of the refining process, and the silicon content is less than 5 ppm by weight.

[0173] Preferably, the halogen (especially chlorine) content is less than 3 ppm by weight at the outlet of the purification process.

[0174] The content is given as a relative weight concentration, expressed as a percentage by weight (%), parts per million (ppm), or parts per billion (ppb), relative to the total weight of the flow under consideration.

[0175] (Hydrocracking process (optional)) In a modified version, the method of the present invention may include a hydrocracking step, which is carried out either immediately after the hydrotreatment step or after the fractionation step for the intermediate distillate fraction. Compounds with boiling points above 175°C contain more naphthenic, naphthenic-aromatic, and aromatic compounds relative to lighter compounds, thus resulting in a higher C / H ratio. This high ratio causes coking in the steam cracker, thus requiring a steam cracking furnace dedicated to this fraction. If it is desirable to minimize the yield of these heavy compounds (intermediate distillate fraction) and maximize the yield of light compounds (naphtha fraction), these compounds can be at least partially converted by hydrocracking to lighter compounds generally preferred by steam cracking units.

[0176] Therefore, the method of the present invention may include a hydrocracking step, which is carried out in a hydrocracking reaction section, using at least one fixed-bed reactor having n catalyst beds, where n is an integer of 1 or more, each containing at least one type of hydrocracking catalyst, the hydrocracking reaction section is fed the hydrogenated effluent and / or intermediate distillate fraction obtained from the fractionation step and a hydrogen-containing gas stream, the average temperature when the hydrocracking reaction section is carried out is 250 to 450°C, the hydrogen partial pressure is 1.5 to 20.0 absolute MPa, and the spatiotemporal velocity is 0.1 to 10.0 h -1 This yields hydrocracking effluent, which is then sent to a fractionation step, and subsequently, preferably, a steam decomposition step c).

[0177] Therefore, the average temperature during the hydrogenolysis reaction section is advantageously 250-480°C, preferably 320-450°C, the hydrogen partial pressure is 1.5-20.0 absolute MPa, preferably 2-18.0 absolute MPa, and the space-spatiotemporal velocity (HSV) is 0.1-10.0 h. -1 Preferably 0.1 to 5.0 hours -1 Prioritizing 0.2-4 hours -1 Therefore, the hydrogen coating rate is advantageous in the hydrocracking process, which is the volume (m³) of the feed material supplied to the hydrocracking process. 3 ) Hydrogen per unit: 80-2000 Nm 3 Preferably, the volume of the feed material to be supplied to the hydrocracking process (m³ 3 ) Hydrogen per unit: 200-1800 Nm 3 The definitions of mean temperature (WABT), HSV, and hydrogen coverage correspond to the definitions above.

[0178] The hydrogenation and hydrocracking processes can, advantageously, be carried out in the same reactor or in different reactors. If they are carried out in the same reactor, the reactor comprises several catalyst beds, the first catalyst bed containing one or more hydrogenation catalysts, and subsequent catalyst beds containing one or more hydrocracking catalysts.

[0179] The hydrocracking process can be carried out in one or two steps. If it is carried out in two steps, the effluent from the first hydrocracking step is separated to obtain a heavy fraction (unreacted intermediate distillate fraction), which is then introduced into a second hydrocracking step, which includes a dedicated second hydrocracking section distinct from the first hydrocracking section. This configuration is particularly suitable when it is desired to produce only a naphtha fraction. Preferred operating conditions and catalysts used in the second hydrocracking step are those described for the first hydrocracking step. The operating conditions and catalysts used in the two hydrocracking steps may be the same or different.

[0180] One or more types of hydrocracking catalysts used in one or more hydrocracking steps are conventional hydrocracking catalysts known to those skilled in the art, and are of a dual-functional type that combines acid function with hydrogenation and dehydrogenation function, and may be combined with at least one type of binding matrix. The acidic functional material has a high surface area (generally 150-800 m²) that exhibits surface acidity. 2 The hydrogenated dehydrogenated functional is composed of a support of ( / g), such as halogenated (especially chlorinated or fluorinated) alumina, a combination of boron and aluminum oxides, amorphous silica-alumina, and zeolites. The hydrogenated dehydrogenated functional is contributed by at least one metal from Group VIB of the periodic table and / or at least one metal from Group VIII. Hydrogenated dehydrogenated functionals of the type NiMo, NiMoW, or NiW are preferred.

[0181] (List of drawings) While further details of the elements referenced in Figures 1-3 will allow for a better understanding of the present invention, the present invention is not limited to the specific embodiments shown in Figures 1-3. The various embodiments presented can be used individually or in combination with each other, and there are no restrictions on the combinations.

[0182] Figure 1 shows a diagram of a general embodiment of the method of the present invention.

[0183] A feedstock (1) containing plastics and / or tires and / or SRF is thermally decomposed in a thermal or catalytic pyrolysis unit (U1) to produce at least a first gaseous effluent (2) (pyrolysis gas) containing a mixture of hydrocarbons including H2, CO, CO2 and C1-C6 hydrocarbons, and a first liquid effluent (3) (pyrolysis oil) mainly containing C7+ hydrocarbons.

[0184] The first gaseous effluent (2), which contains a mixture of hydrocarbons including H2, CO, CO2, and C1-C6 hydrocarbons, is then compressed (K1) and then cooled (E1) to enable the recovery of a second liquid effluent (4) (condensate) in a separator drum (D1) which mainly contains C3-C6 hydrocarbons but contains little CO and CO2, and a residual second gaseous effluent (8) (non-condensable gas flow) concentrated with H2, CO, and CO2.

[0185] As shown in Figure 1, the solid stream (10) containing carbon ("char") is also extracted from the pyrolysis unit.

[0186] The second liquid effluent (4), which mainly contains C3-C6 hydrocarbons, is advantageously sent to a purification unit (U2) used to purify the second liquid effluent (4) and to meet the specifications of a feedstock that can be processed in a steam cracking unit (U3). If the purification unit is a hydrogenation unit, hydrogen (5) is injected.

[0187] The first liquid effluent (3), which mainly contains C7+ hydrocarbons, is also advantageously introduced into the purification unit (U2).

[0188] The hydrogenation unit may be followed by a washing / separation unit (not shown) that specifically enables the removal of chlorine (in the form of HCl and salts).

[0189] The second gaseous effluent (8) obtained from the separator drum (D1) is rich in H2, CO, and CO2, and can be sent in whole or in part to a pyrolysis unit to provide the energy required for the method, or transferred to another onboard facility and upgraded as fuel (9).

[0190] Downstream of the hydrogenation or chlorine removal section, a separation unit (not shown in Figure 1) may be present, configured to separate "non-condensable" compounds (H2, CO, CO2, H2S) and may recover the C3+ hydrocarbon stream. According to a preferred embodiment, the separation unit is a stabilization unit (depentaner) from which a C5+ compound-rich liquid hydrocarbon stream (7) is withdrawn at the bottom of the column, and a non-condensable gas stream and fraction (6) containing C3-C4 hydrocarbons are withdrawn at the top of the column after condensation of the top gas.

[0191] As shown in Figure 1, all or part of the hydrocarbon stream (6) is, in some cases, sent to a steam decomposition unit (U3) after a purification step (e.g., washing with amines, water, or sodium hydroxide). As shown in the figure, the hydrocarbon stream (6) can be separated into two parts, one of which is used as a fuel gas to provide some of the energy required for the operation of the pyrolysis unit (U1), and the other part is sent to a steam decomposition unit (U3) to produce a mixture of C3-C4 olefins (e.g., propylene, butylene, butadiene).

[0192] According to a preferred embodiment shown in Figure 1, there is a shared steam decomposition unit (U3), which is configured to treat a C5+ hydrocarbon stream (7) and a hydrocarbon stream (6) containing C3-C4 hydrocarbons as a mixture.

[0193] Figure 2 shows a diagram of another specific embodiment of the method of the present invention, which is based on the diagram of Figure 1, wherein the second liquid effluent (4) (condensate) obtained from the separator drum (D1) is sent to the steam decomposition unit (U3) after a chlorine removal step, but does not undergo processing in the purification unit (U2). This operating mode is particularly applicable to processing the condensate by co-processing it with another feed material whose specifications are compatible with those of the steam decomposition unit feed material.

[0194] Figure 3 shows a diagram of another specific embodiment of the method of the present invention, based on the diagram of Figure 1, wherein at least a portion of the first liquid effluent (11) is introduced into a separation unit (D1), such as an adsorbent column or separator drum. The first liquid effluent (11) may also be mixed with a compressed first gaseous effluent (2) upstream or downstream of cooling, and the mixture is sent to the separation unit (D1) (dotted arrow).

[0195] The separation unit (D1) makes it possible to obtain an intermediate liquid effluent (11') and a residual second gaseous effluent (8) concentrated with H2, CO, and CO2. This residual second gaseous effluent (8) is recycled to the pyrolysis unit (U1) to generate the energy required for this method.

[0196] The intermediate liquid effluent (11') is enriched with light (especially C2) hydrocarbon compounds by the "sponge" effect, and is introduced into a second separation unit (D2) to obtain the second liquid effluent (4) mainly containing C3+ (and some C2) hydrocarbons, and a residual third gaseous effluent (12) concentrated with H2, CO, and CO2.

[0197] The residual third gaseous effluent (12) is concentrated by light components. These light components may include CO, CO2, and methane, but also include certain light hydrocarbon components, particularly ethylene and heavier hydrocarbon compounds. The residual third gaseous effluent (12) is preferably recycled upstream of its compression or cooling and mixed with the first gaseous effluent (2), and some of the light hydrocarbon components can be recovered into the liquid phase from the separation unit (D1).

[0198] Only the main processes, along with the main flow, are shown in the diagram to allow for a better understanding of the present invention. Even if not shown, it is clearly understood that all the equipment necessary for the operation (drums, pumps, exchangers, furnaces, towers, etc.) is present.

[0199] (Examples) (Example 1) The embodiment is based on the embodiment shown in Figure 1.

[0200] The raw material for the plastic waste originating from the sorting channel is thermally decomposed in unit (U1) at a temperature of 470°C in the absence of oxygen. The first liquid effluent (C7+) of the pyrolysis product (3) resulting from the pyrolysis reaction is sent to a purification unit (U2) to saturate it with olefins and diolefins, and then unwanted impurities, namely silicon, nitrogen, sulfur, chlorine, and metals (Si, P, K, Na, Hg, As, etc.), are removed in a steam decomposition unit (U3). The first gaseous effluent (2), which is rich in CO / CO2, is withdrawn from the pyrolysis unit (U1), then compressed, then cooled, and sent to a separator drum. This separator drum is operated at a pressure of 1.1 relative MPa (11 barg) and a temperature of 40°C, thereby separating the second liquid effluent (4), which is rich in hydrocarbons (C3+) but has a drastically reduced CO / CO2 content, from the second gaseous effluent, which is rich in H2, CO, and CO2, and using this to provide the energy required for the pyrolysis reaction (U1). The second liquid effluent (4) (condensate) obtained from the drum (D1) has an acceptable content of CO and CO2, and is sent into the unit (U2) to reduce the content of impurities Si, N, metals, and especially chlorine, although this is still too high for the specifications of the steam decomposition unit (U3). The flow (4) is then processed in the purification unit (U2) as a mixture with the pyrolysis product (3) to achieve the required specifications at the inlet of the steam decomposition unit (U3).

[0201] Table 1 shows the pressure, temperature, and flow rate for flows (2), (4), and (8).

[0202] In the following embodiment (Table 2), the first liquid effluent (3) accounts for 70% by weight of the plastic feed material introduced into the pyrolysis unit (U1), while the second liquid effluent (4) accounts for 8% by weight of the plastic feed material introduced into the pyrolysis unit (U1). Therefore, by recombining the two flows (3) and (4), the material yield increases from 70% to 78%, i.e., an increase of approximately 11%. This increase in yield remains the same at the outlet of the purification unit (U2), and therefore at the inlet of the steam decomposition unit (U3), as long as all the hydrocarbon flow produced by the purification unit (U2) is sent to the steam decomposition unit (U3). This implies that if a stabilization process (removal of non-condensable gases) is performed following the purification process in the purification unit (U2), all of the hydrocarbon-containing liquid effluent obtained from the stabilization process will be sent to the steam decomposition unit (U3), thereby making it possible to increase the olefin yield.

[0203] [Table 1]

[0204] [Table 2]

[0205] (Example 2) Example 2 is based on the embodiment shown in Figure 3.

[0206] Example 2 was carried out under the same thermal decomposition conditions as Example 1, using the same plastic supply material as in Example 1.

[0207] In this embodiment, the entirety of the first liquid effluent (C7+)(11) recovered from the pyrolysis unit (U1) is sent to the top of an adsorbent column (D1) operated at 12 barg and 40°C, together with the compressed and cooled first gaseous effluent (2). Before contact, the first gaseous effluent (2) is compressed and cooled as in Example 1, and then introduced to the bottom of the adsorbent column (D1).

[0208] The adsorption column (D1) recovers an intermediate liquid effluent (11') that is rich in hydrocarbons (C3+) but has a drastically reduced CO / CO2 content, and a residual second gaseous effluent (8) that is rich in H2, CO, and CO2. The residual second gaseous effluent (8) is used to provide the energy required for the pyrolysis reaction (U1). The intermediate liquid effluent (11') is sent to a separation unit (D2), which is a distillation column.

[0209] The separation unit (D2) recovers residual third gaseous effluent (12) and second liquid effluent (4). The residual third gaseous effluent (12) is recycled entirely to the compressor (K1), and the second liquid effluent (4) is introduced into the purification unit (U2). The flow (4) is then processed in the purification unit (U2) as a mixture with the pyrolysis product (3) to achieve the required specifications at the inlet of the steam decomposer (U3).

[0210] Table 3 shows the operating conditions under which contact / mixing occurs in the separation unit (D1) between the first liquid effluent (11) and the first gaseous effluent (2). The first liquid effluent (11) accounts for 70% by weight of the flow recovered from unit (U1), and the first gaseous effluent (2) accounts for 20% by weight of the flow collected from unit (U1). This table also shows the composition of flows (2), (11), (4), (8), and (12), as well as their impurity (chloromethane) content.

[0211] Table 4 shows the flow rates for flows (1), (4), and (8).

[0212] [Table 3]

[0213] [Table 4]

[0214] As shown in Tables 3 and 4, the stream (4) recovered from the separation unit (D2) accounts for approximately 87% by weight of the feed material processed in unit (U1). Stream (4) contains a low content of CO+CO2 (less than 50 ppm) and essentially few light C1 hydrocarbons, but includes some upgradeable C2 hydrocarbons. This thus improves the olefin production yield when stream (4) is processed in the purification unit (U2), and the effluent is steam-decomposed in unit (U3).

[0215] The flow rate of the second gaseous effluent (8) has been reduced to 2.4%, and the second gaseous effluent (8) has a reduced content of organic chlorides, such as chloromethane, which is reduced from the initial 50 ppm to 5 ppm. The flow (8) is therefore smaller and has a lower impurity content, which allows for easy upgrades, for example, as a fuel gas. [Brief explanation of the drawing]

[0216] [Figure 1] This figure shows a general embodiment of the method of the present invention. [Figure 2] This figure shows another specific embodiment of the method of the present invention. [Figure 3] This figure shows another specific embodiment of the method of the present invention.

Claims

1. A method for producing olefins from feedstock containing plastics and / or tires and / or solid recovery fuel, comprising the following steps: (a) Pyrolysis process in a pyrolysis unit of feedstock containing plastics and / or tires and / or solid recovered fuel; H ２ CO, CO ２ The first gaseous effluent (2) containing a mixture of hydrocarbons including C1-C6 hydrocarbons, and the first liquid effluent (3) mainly containing C7+ hydrocarbons are recovered; (b) A step of compressing the first gaseous effluent (2) obtained from step a), then cooling it, and then separating the compressed and cooled first gaseous effluent in a separation unit; a second liquid effluent (4) mainly containing C3+ hydrocarbons and H ２ CO and CO ２ A concentrated residual second gaseous effluent (8) is obtained; (c) A step of introducing the second liquid effluent (4) into a steam decomposition unit in the presence of water vapor; to produce olefins.

2. The method according to claim 1, wherein the first liquid outflow (3) is introduced into the steam decomposition unit of step c).

3. In step b), at least a portion of the first liquid effluent (11) is introduced into the separation unit as a mixture with the compressed first gaseous effluent (2) or not as a mixture, and then the mixture is separated into an intermediate liquid effluent (11') and H ２ CO and CO ２ The concentrated residual second gaseous effluent (8) is obtained, and then the intermediate liquid effluent (11') is separated in a second separation unit to obtain the second liquid effluent (4) which mainly contains C3+ hydrocarbons, and H ２ CO and CO ２ The method according to claim 1 or 2, wherein a concentrated residual third gaseous effluent (12) is obtained.

4. The method according to any one of claims 1 to 3, wherein the step of purifying the second liquid effluent (4) obtained from step b) is carried out in a purification unit upstream of the steam decomposition unit in step c).

5. The method according to any one of claims 1 to 4, wherein the step of purifying the first liquid effluent (3) obtained from step a) is carried out in a purification unit upstream of the steam decomposition unit in step c).

6. The method according to any one of claims 1 to 5, wherein step b) is performed such that, during one or more separations, the pressure becomes 0.5 to 2.5 relative MPa, preferably 1.0 to 1.5 relative MPa, and the temperature becomes 20 to 55°C, preferably 30 to 45°C.

7. The method according to any one of claims 4 to 6, wherein the purification step includes a step of pre-treating the second liquid effluent (4) obtained from step b) and / or the first liquid effluent (3) obtained from step a), the pre-treatment step being carried out upstream of step c), and the pre-treatment step including an adsorption step and / or a filtration step and / or a centrifugation step and / or a decantation step and / or an electrostatic separation step and / or a washing step with an aqueous solution and / or a gas stripping step.

8. The purification process includes a hydrogenation process carried out in a hydrogenation reaction section, using at least one fixed bed reactor having n catalyst beds, where n is an integer of 1 or more, each containing at least one hydrogenation catalyst. In the hydrogenation reaction section, the optionally pre-treated second liquid effluent obtained from step b) and / or the optionally pre-treated first liquid effluent obtained from step a) are fed together with an air stream containing hydrogen. The average temperature during the implementation of the hydrogenation reaction section is 150 to 430 °C, the hydrogen partial pressure is 1.0 to 10.0 absolute MPa, and the space-time velocity is 0.1 to 10.0 h －１ A method according to any one of claims 4 to 7, wherein a purified second liquid effluent and / or a purified first liquid effluent are obtained.

9. The method according to claim 8, wherein the hydrogenation catalyst comprises a support selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof, and a hydrogenation-dehydrogenation functional element comprising at least one element from Group VIII and at least one element from Group VIB, or at least one element from Group VIII.

10. The method according to claim 8 or 9, wherein, following the hydrogenation step, a washing / separation step is performed, and the optionally pre-treated and purified second liquid effluent and / or the optionally pre-treated and purified first liquid effluent and an aqueous solution are fed to obtain at least a gaseous effluent, an aqueous effluent and the washed and purified second liquid effluent and / or the washed and purified first liquid effluent.

11. The method according to any one of claims 4 to 10, wherein the optionally pretreated and / or washed and purified second liquid effluent and / or the optionally pretreated and / or washed and purified first liquid effluent are subjected to at least one fractionation step in a fractionation unit to obtain at least one gas stream and at least one liquid stream of C3+ hydrocarbons.

12. The method according to claim 11, wherein the separation unit includes a depentane column, and extracts liquid streams of liquid C3-C4 hydrocarbons and C5+ liquid hydrocarbons from the depentane column.

13. The method according to claim 11 or 12, wherein at least one of the liquid streams obtained from the fractionation step is sent, at least in part, to the steam decomposition unit in step c).

14. The method according to any one of claims 1 to 13, wherein the steam decomposition step c) is carried out in the presence of steam in at least one pyrolysis furnace, the temperature at which the step is carried out is 700 to 900°C, and the pressure at which the step is carried out is 0.05 to 0.3 relative MPa.

15. The method according to any one of claims 1 to 14, wherein in the steam decomposition step c), the residence time of the hydrocarbon compound is 1.0 second or less, and the amount of water introduced is in the form of steam, at the inlet of the steam decomposition step c), 0.3 to 3.0 kg of water per kg of the hydrocarbon compound.

16. The method according to any one of claims 1 to 15, wherein the supplied raw materials consist of plastics and / or tires and / or solid recycled fuel.

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