PROCESS FOR PRODUCING PARAFFINS BY HYDROTREATMENT OF FEEDSTOCKS FROM PLASTIC WASTE

Abstract

The present invention relates to a process for producing paraffins by hydrotreatment, in particular from a composition comprising a plastic liquefaction oil, said composition comprising paraffins, olefins, aromatics and heteroatoms.The process comprises: (a) a step of separating a portion of the paraffins and olefins contained in said composition comprising at least one step of crystallization (i) of said composition by lowering the temperature from 10°C to 60°C from an initial temperature at which said composition is entirely liquid and obtaining a mixture comprising a solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms and an effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms, followed by at least one step of separation (ii) of said solid product and said effluent, (b) a step of hydrotreatment of the solid product of step (a) during which the olefins contained in said solid product are hydrogenated and an effluent containing paraffins and at most 2% m / m of olefins is produced. Abstract figure: without.

Description

Title of the invention: PROCESS FOR THE PRODUCTION OF PARAFFINS BY HYDROTREATMENT OF FEEDSTOCKS FROM PLASTIC WASTE Technical field

[0001] The present invention relates to a process for producing paraffins by hydrotreatment, in particular from feedstocks originating from plastic waste. Context of the invention

[0002] Paraffins, especially waxes, are most often obtained by refining hydrocarbons of fossil origin.

[0003] Waxes are in particular mixtures of linear or branched paraffins (n- and iso-alkanes) whose carbon chain generally contains more than 18 carbon atoms, and potentially up to more than 100 carbon atoms. The melting points of paraffins increase with the number of carbons. For C18+ paraffins, this melting point (measured according to ASTM D87:2009) is generally above 25°C, and is typically above 70°C for paraffins used as waxes.

[0004] Waxes are mainly used, pure or in mixtures with additives, for coating paper, cardboard, containers, metals, etc. (waterproofing or protection), for thermal insulation, for the manufacture of candles (flash point between 200°C and 250°C), in mixtures with chemical products, for the manufacture of chlorinated paraffins, for the waterproofing of fabrics, for the waterproofing of particle boards, etc.

[0005] With the scarcity of fossil resources and growing environmental constraints, manufacturers are looking for other hydrocarbon feedstocks to produce paraffins and in particular waxes.

[0006] Furthermore, the significant quantities of plastic waste produced and the environmental problems they generate have led manufacturers to seek ways to recycle this waste, in particular those making it possible to produce new monomers and then polymers and thus to complete the life cycle of the plastic. This recycling route is a chemical route consisting of liquefying the plastic waste, in particular by thermal means (typically by pyrolysis or by hydrothermal liquefaction), then reintroducing the effluent produced into a conventional refining circuit. This liquefaction is however energy-intensive and is therefore only considered for treating contaminated plastic waste, which cannot be treated in another way (by mechanical recycling or depolymerization for example).

[0007] The significant amount of impurities present in plastic waste liquefaction oils requires them to be pretreated before being injected into a conventional refining circuit. Thus, pyrolysis or hydrothermal liquefaction of plastic waste is typically followed by purification including hydrotreatment and removal of contaminants using various purification processes such as distillation.

[0008] There are thus numerous pretreatment processes focused on the removal of chlorinated compounds. However, other impurities present in plastic liquefaction oil simply prohibit their direct use in other refining processes. In particular, oxygenated compounds present in plastic liquefaction oil can be converted into peroxides and thus promote the formation of polymers and gums from the olefins present in the plastic liquefaction oil. In particular, the presence of olefins and oxygenated compounds can lead to undesirable polymerization during storage, transport from the place of production to the place of further processing as well as during purification and further processing treatments. Since purification operations are often carried out at high temperatures, an increase in the rate of undesirable polymerization can thus be observed.

[0009] Document WO2021 / 115982 describes a process for the recovery by dewaxing of aliphatic hydrocarbons from a hydrocarbon feedstock comprising aliphatic hydrocarbons and polar compounds containing a heteroatom. This feedstock includes the liquid products from the pyrolysis of plastic waste. The process described consists of mixing the feedstock to be treated with a solvent, cooling the mixture in a temperature range of 5°C to -30°C to obtain wax crystals and separating them in order to produce aliphatic hydrocarbons comprising wax and a dewaxed liquid comprising the solvent, the polar compounds and optionally aromatics. This document provides for steam cracking of the aliphatic hydrocarbons comprising wax directly, without intermediate hydrotreatment. These aliphatic hydrocarbons are defined as non-olefinic (paraffinic) aliphatic compounds and olefinic aliphatic compounds.The production of paraffins is not described.

[0010] Furthermore, the behavior of plastic waste liquefaction oils is difficult to predict due to the complexity of these oils. For example, gas chromatographic analysis of plastic waste pyrolysis oil only allows 25 to 45% by weight of compounds containing oxygen and nitrogen to be identified. Furthermore, the composition of these oils varies greatly depending on the nature of the plastic waste treated.

[0011] There is therefore a continuing need to develop methods for producing high-value chemical products from plastic waste, regardless of its origin, in particular by using existing conventional refining units. Summary of the invention

[0012] The invention aims to provide a process for producing paraffins by hydrotreatment from a composition comprising a plastic liquefaction oil, said composition comprising paraffins, olefins, aromatics and heteroatoms, the process comprising:

[0013] (a) a step of separating a portion of the paraffins and olefins contained in said composition comprising at least one step of crystallization (i) of said composition by lowering the temperature from 10°C to 60°C from an initial temperature at which said composition is entirely liquid and obtaining a mixture comprising a solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms, and an effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms, followed by at least one step of separation (ii) of said solid product and said effluent,

[0014] (b) a step of hydrotreating the solid product of step (a) during which the olefins contained in said solid product are hydrogenated and an effluent containing paraffins and at most 2% m / m of olefins is produced.

[0015] This particular sequence of steps makes it possible to treat in a hydrotreatment reactor a solid originating from a composition comprising a plastic liquefaction oil but having olefin, aromatic and heteroatom contents conforming to those required at the inlet of a hydrotreatment reactor process, regardless of the contaminant content of the composition.

[0016] The composition treated by the process according to the invention may comprise at least 2% by mass of plastic liquefaction oil(s). The remainder may then be composed of at most 98% by mass of a diluent or solvent such as a hydrocarbon and / or one or more components such as: a biomass liquefaction oil such as Panicum virgatum, a tall oil, a used edible oil, an animal fat, a vegetable oil such as rapeseed, canola, castor, palm, soybean oil, an oil extracted from an algae, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, a biomass liquefaction oil such as a lignocellulosic biomass such as a wood, paper and / or cardboard liquefaction oil, an oil obtained by pyrolysis of crushed used furniture, an elastomer liquefaction oil for example possibly vulcanized latex or tires, as well as mixtures thereof.

[0017] In one embodiment, the composition may comprise at least 5% by mass, at least 10% by mass, at least 25% by mass, at least 50% by mass, at least less than 75% by mass, at least 90% by mass or 100% by mass of plastic liquefaction oil(s). The mass content of plastic liquefaction oil(s) in the composition may be within any range defined by two of the limits previously set.

[0018] The heteroatoms contained in the composition treated in the present invention may be oxygen, nitrogen, sulfur, silicon, a metal and / or a halogen, in particular chlorine.

[0019] The solid product from step (a) may contain from 50% m / m to 90% m / m of paraffins, from 10 to 40% m / m of olefins, from 0 to 2% m / m of aromatics, from 2 to 15% m / m of naphthenes, and optionally at most 2% m / m of heteroatoms.

[0020] The paraffins produced in step (b) may contain from 0 to 2% m / m of olefins, preferably from 0 to 1% m / m. Their total heteroatom content may be from 0 to 1% m / m. Thus, the effluent produced in step (b) may contain 70% m / m or more of paraffins, preferably 80% m / m or more of paraffins, more preferably 90% m / m or more of paraffins, in particular 97% m / m or more of paraffins, preferably 98% m / m or more of paraffins.

[0021] Advantageously, the paraffins produced in step (b) may also contain:

[0022] - at most 100 ppm of oxygen (measured according to the ASTM D5622 / D2504 standard), - at most 20 ppm of nitrogen (measured according to the ASTM D4629 standard), - at most 500 ppm of sulfur (measured according to the ISO 20846 standard), - not more than 120 ppm chlorine (measured according to ASTM D7359-18).

[0023] In one embodiment, during separation step (a), said composition may be mixed with at least one solvent prior to at least one crystallization step (i). It will then be possible to advantageously provide a step of separating at least one solvent from the effluent from separation step (iii) and returning at least one solvent separated to step (i).

[0024] The solvent may advantageously be an organic solvent, for example chosen from an aliphatic hydrocarbon, an aromatic hydrocarbon, a ketone, an alcohol or their mixtures, preferably a ketone or an alcohol. Examples of solvents which can be used include acetone, methyl ethyl ketone, isopropanol.

[0025] In particular, a solvent or a mixture of solvents may be chosen which does not crystallize at the crystallization temperature of the paraffins to be separated, preferably a solvent or a mixture of solvents in the liquid state and miscible with the composition at the temperatures for carrying out step (a) of the process of the present invention and in particular at least one crystallization step (i).

[0026] The volume ratio of said composition to the solvent may be from 10 / 90v / v to 90 / 10v / v, or from 20 / 80v / v to 80 / 20 v / v, preferably from 40 / 60v / v to 60 / 40v / v or from 45 / 55v / v to 55 / 45v / v, for example 50 / 50 v / v, or in any interval defined by two of these ratios.

[0027] The separation step (a) can be carried out in a single step or in two steps to improve the separation and recovery of paraffins. The separation step (a) can then comprise:

[0028] (i-1) a first crystallization step by lowering the temperature of said composition from 10°C to 60°C from a first initial temperature at which said composition is entirely liquid and obtaining a first mixture comprising a first solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms, and a first effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms,

[0029] (ii-1) a first step of separating said first solid product and said first effluent,

[0030] (i-2) a second crystallization step by lowering the temperature of said first effluent from 10°C to 60°C from a second initial temperature at which said first effluent is entirely liquid and obtaining a second mixture comprising a second solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms, and a second effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms.

[0031] (ii-2) a second step of separating said second solid product and said second effluent, and

[0032] the first solid product and the second solid product are subjected to hydrotreatment step (b).

[0033] When a solvent or solvent mixture is added to the composition, it is then added before the first crystallization step (i-1). Preferably, no solvent is added before the second crystallization step (i-2).

[0034] The crystallization step (i) or each of the crystallization steps (i-1) and (i-2) is carried out from an initial temperature at which the composition (alone or in a mixture with a solvent), or the first effluent, is entirely liquid, up to a final temperature, 10 to 60°C lower than the initial temperature.

[0035] The initial temperature can be easily determined by a person skilled in the art using standard measuring methods. The initial temperature is typically higher (for example by 5 to 10°C) than the crystallization temperature of the paraffins to be separated from the composition. This crystallization temperature can be determined by differential scanning calorimetry measurements (P.Claudy et al, Diesel fuels: determination of onset crys-tallization temperature, pour point and filter plugging point by differential scanning calorimetry. Correlation with standard test methods. Fuel, 1986, vol 65, pp 861-4).

[0036] During separation step (a), separation step (ii), (ii-1) or (ii-2) can be carried out by at least one step chosen from filtration, decantation, centra trifugation. This separation step (ii), (ii-1) or (ii-2) is typically carried out at a temperature lower than or equal to the final temperature in order to recover the solid product.

[0037] In one embodiment, the solid product from step (a), before being hydrotreated in step (b), may be washed, in one or more times, typically three times, with at least one solvent, preferably at a temperature lower than or equal to the final temperature. This solvent is as defined above. When at least one solvent is used during the crystallization step (i), (i-1) or (i-2), the same solvent or mixture of solvents may advantageously be used for this washing step. This washing step may advantageously be followed by a step of drying or evaporation of the washed solid product, making it possible to remove the residual solvent(s) before the hydrotreatment (b).

[0038] During the hydrotreatment of step (b), 98% m / m or more of the olefins can be hydrogenated, in particular by choosing suitable operating conditions.

[0039] The hydrotreatment of step (b) can be carried out in a single step or in two steps. When carried out in a single step, the solid product(s) from step (a) are hydrogenated at a temperature of 200 to 450°C, preferably 200 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bar, preferably 30 to 100 bar and in the presence of a hydrotreatment catalyst, for example a hydrogenation catalyst comprising NiMo (0.1-60% by mass) and / or CoMo (0.1-60% by mass).

[0040] Alternatively, the hydrotreatment of step (b) can be carried out in a first step (b-1) in which the solid product(s) from step (a) are hydrogenated at a temperature of 80 to 250°C, preferably 130 to 190°C in the presence of hydrogen at an absolute pressure of 5 to 60 bars, preferably 20 to 30 bars and in the presence of a first hydrotreatment catalyst, for example a hydrogenation catalyst comprising Pd (0.1-10% by weight) and / or Ni (0.1-60% by weight) and / or NiMo (0.1-60% by weight), and in a second step (b-2) in which the effluent from step (b-1) is hydrogenated at a temperature of 200 to 450°C, preferably 200 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence of a second hydrotreatment catalyst, for example a hydrogenation catalyst comprising NiMo (0.1-60% by weight) and / or CoMo (0.1-60% by weight).The first step can then allow the hydrogenation of dienes initially present in the composition and which have been crystallized with the paraffins in the solid product(s).

[0041] The invention also relates to a method for recovering plastic waste comprising the following steps: (A) a step of liquefaction of waste containing plastics and obtaining a hydrocarbon product comprising a gaseous phase, a liquid phase and a solid phase, (B) a step of separating the liquid phase from said product, said liquid phase forming a plastic liquefaction oil, (C) a step of treating at least part of the liquid phase by a process for producing paraffins according to the invention.

[0042] The liquefaction step (A) may comprise a pyrolysis step typically carried out at a temperature of 300 to 1000°C or 400 to 700°C, this pyrolysis being for example a rapid pyrolysis, a flash pyrolysis, or a catalytic pyrolysis or a hydropyrolysis.

[0043] Alternatively or in combination, the liquefaction step (A) may comprise a hydrothermal liquefaction step, typically carried out at a temperature of 250 to 500°C and at pressures of 10 to 25-40 MPa.

[0044] The waste treated in step (A) may be plastic waste possibly mixed with biomass, as previously described.

[0045] The separation step (B) makes it possible to eliminate the gaseous phase, essentially the C1-C4 hydrocarbons and the solid phase (typically char) to recover only the liquid organic phase forming a liquefaction oil.

[0046] This plastic liquefaction oil typically comprises from 30 to 55% by mass of paraffins, from 10 to 50% m / m of olefins, from 5 to 12% m / m of aromatics. These contents can be determined by gas chromatography.

[0047] In particular, a plastic liquefaction oil may comprise a Bromine index of 20 to 60 g Br / 100 g and / or a maleic anhydride index (UOP326-82) of 1 to 20 mg maleic anhydride / 1 g.

[0048] A plastic liquefaction oil may further comprise one or more of the following heteroatom contents: 0 to 8% m / m oxygen, 250 to 3800 ppm nitrogen, 35 to 850 ppm sulfur, 34 to 900 ppm metals, 50 to 6000 ppm chlorine, 0 to 100 ppm bromine, 1.5 to 100 ppm fluorine.

[0049] This liquid phase can then be subjected, in part or in whole, to the olefin production process of the invention, alone or in a mixture with other components to produce the paraffins of interest by hydrotreatment. Definitions

[0050] The terms "comprising" and "comprises" as used herein are synonymous with "including," "includes," or "contains," "containing," and are inclusive or unbounded and do not exclude additional features, elements, or method steps not specified.

[0051] The expressions % by weight and % by mass have an equivalent meaning and refer to the proportion of the mass of a product relative to 100g of a composition. including.

[0052] The expression "plastic liquefaction oil" or "oil resulting from the liquefaction of plastic" or "plastic waste liquefaction oil" or "liquefaction oil resulting from the pyrolysis of waste containing plastics" refers to the liquid products obtained at the end of pyrolysis or hydrothermal liquefaction of thermoplastic, thermosetting or elastomeric polymers, alone or in a mixture and generally in the form of waste, optionally in a mixture with at least one other waste such as biomass, for example chosen from lignocellulosic biomass, paper and cardboard.

[0053] The pyrolysis process must be understood as a thermal cracking process, carried out in the presence or absence of a catalyst (for example, catalytic or non-catalytic fast pyrolysis, etc.). The hydrothermal liquefaction process (or HTL for "Hydrothermal Liquefaction" in English) is a thermochemical conversion process using water as a solvent, reactant and catalyst for the degradation reactions of plastics or biomass, the water typically being in a subcritical or supercritical state.

[0054] The plastic can be of any type, including any type of new or used plastic, included in household (post-consumer) or industrial waste. Plastics are understood to mean materials made of polymers and optionally auxiliary components such as plasticizers, fillers, colorants, catalysts, flame retardants, stabilizers, etc. For example, these polymers can be halogenated polyethylene (Cl, F) or not, polypropylene, polystyrene, polybutadiene, polyisoprene, poly(ethylene terephthalate) (PET), acrylonitrile-butadiene-styrene (ABS), polybutylene, poly(butylene terephthalate) (PBT), polyvinyl chloride (PVC), polyvinylidene chloride, a polyester, a polyamide, a polycarbonate, a polyether, an epoxy polymer, a polyacetal, a polyimide, a polyesteramide, silicone, etc.Generally speaking, any polymer or mixture of polymers capable of producing paraffins by liquefaction can be used.

[0055] These liquefaction pyrolysis oils contain paraffins, i-paraffins (iso-paraffins), dienes, alkynes, olefins, naphthenes and aromatics. The plastic liquefaction oils also contain impurities containing heteroatoms, such as chlorinated, oxygenated and / or silylated organic compounds, metals, salts, phosphorus, sulfur, and nitrogen compounds.

[0056] The composition of the plastic liquefaction oil is dependent on the nature of the liquefied plastic and is essentially (in particular at more than 80% m / m, most often at more than 90% m / m) made up of hydrocarbons having from 1 to 150 carbon atoms and impurities.

[0057] Biomass can be defined as an organic plant or animal product. Biomass thus includes (i) biomass produced by surplus agricultural land, not used for human or animal food: dedicated crops, called energy crops; (ii) biomass produced by deforestation (forest maintenance) or the clearing of agricultural land; (iii) agricultural residues from cereal crops, vines, orchards, olive trees, fruits and vegetables, agri-food residues, etc.; (iv) forest residues from forestry and wood processing; (v) agricultural residues from livestock farming (manure, slurry, bedding, droppings, etc.); (vi) household organic waste (paper, cardboard, green waste, etc.); (vii) ordinary industrial organic waste (paper, cardboard, wood, putrescible waste, etc.).The liquefaction oil treated by the invention may come from the liquefaction of waste containing at least 1% m / m, optionally from 1 to 50% m / m, from 2 to 30% m / m or in a range defined by any two of these limits, of one or more of the aforementioned biomasses, residues and organic waste, and the remainder consisting of plastic waste.

[0058] The composition of the plastic liquefaction oil is dependent on the nature of the liquefied plastic and is essentially (in particular at more than 80% m / m, most often at more than 90% m / m) made up of hydrocarbons having from 1 to 150 carbon atoms and impurities.

[0059] The expression "MAV" (acronym for "Maleic Anhydric Value") refers to the UOP326-82 method which is expressed in mg of maleic anhydride which react with 1 g of sample to be measured.

[0060] The term "Bromine Index" is the number of milligrams of bromine that react with 100 g of sample and can be measured according to ASTM DI 159-07 (2017) method.

[0061] The concentration of metals in hydrocarbon matrices can be determined by any known method. Acceptable methods include X-ray fluorescence (XRF) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Analytical scientists know how to identify the most suitable method for measuring each metal and heteroelement depending on the hydrocarbon matrix under consideration.

[0062] The content of paraffins, olefins, naphthenes and aromatic hydrocarbons can be determined by multidimensional gas chromatography, for example according to the method described in the document Duhamel, Journal of Chromatography A, 1387 (2015) 95-103, Comparison of cryogenics and differential flow modulator.

[0063] The melting point of paraffins can be measured according to ASTM D87:2009.

[0064] The oxygen content can be measured according to the standard: ASTM D5622-17 / D2504-88(2015). Nitrogen content can be measured according to the standard: ASTM D4629-17. Sulfur content can be measured according to ISO 20846:2011. The content of halogens, including chlorine, bromine, fluorine, can be measured according to the standard: ASTM D7359-18.

[0065] The particular features, structures, properties, embodiments of the invention may be freely combined into one or more embodiments not specifically described herein, as may be apparent to those skilled in the art in the processing of plastic liquefaction oils using their general knowledge.

[0066] By "hydrotreatment catalyst" is meant a catalyst promoting the incorporation of hydrogen into the products. This type of catalyst is typically a metal catalyst comprising one or more metals from groups 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 of the periodic table. Description of the invention Examples

[0067] Embodiments of the present invention are illustrated by the following non-limiting examples.

[0068] Example 1: separation of paraffins by crystallization in acetone or in an acetone-isopropanol mixture

[0069] A plastic pyrolysis oil HPP1 was mixed at room temperature (i.e. approximately 10°C above the crystallization temperature of the paraffins to be separated) (T° = 25°C, P= latm) with a crystallization solvent (acetone or a 50 / 50 (v / v) mixture of acetone and iso-propanol) to produce a clear homogeneous solution. Then the temperature of the mixture was lowered from this initial temperature of 25°C to a final temperature of -20°C. The formation of a solid product (called cake) was observed. The cake was separated by filtration, washed with the crystallization solvent, then dried and analyzed.

[0070] Table 1 lists the compositions of the pyrolysis oil and the cakes from the two filtrations. It can be seen that the recovered solid product contains mainly paraffins, with a significant quantity of olefins and a very small quantity of aromatics.

[0071] [Tables 1] HPP1 Cake 1 Cake 2 Solvent — Acetone Acetone / zToPro (50 / 50) Ratio (solvent / feed) (v / v) — 50 / 50 50 / 50 Ramp — Quench Quench Final Temperature — -20°C -20°C Yield (%m) 11.5 7.6 FAMILY % m / m % m / m % m / m paraffins 35.8 60.1 63.8 Olefins 42.6 36.1 35.2 Mononaphthenes 6.0 2.8 0.6 Polynaphthenes 5.7 0.7 0.2 Monoaromatics 6.8 0.4 0.2 Diaromatics 0.4 0.0 0.0 Triaromatics 0.0 0.0 0.0 Tetraaromatics + 0.0 0.0 0.0 Unknowns unidentified 0.6 0.0 0.0 Other molecules 2.0 0.0 0.0 TOTAL 100 100 100

[0072] Example 2: Hydrotreatment of the solid product of Example 1

[0073] The solid from Example 1 can be hydrotreated according to the following procedure:

[0074] The solid may be introduced into an optional first hydrotreatment section (HDT1), essentially to hydrogenate the diolefins, and is operated in the liquid phase. This step may comprise a plurality of reactors in series and / or parallel if guard reactors are used upstream or downstream of the first hydrogenation reactor. These guard reactors may make it possible to reduce the concentration of certain undesirable chemical species and / or elements such as chlorine, silicon and metals. Particularly undesirable metals include Si, Na, Ca, Mg, Fe and Hg.

[0075] A second hydrotreatment section (HDT2) is dedicated to the hydrogenation of olefins and to demetallation (HDM), desulfurization (HDS), denitrogenation (HDN) and deoxygenation (HDO). HDT2 is operated in the gas phase. This section consists in one or more reactors operated in series, lead-lag or in parallel.

[0076] Since the hydrotreating reactions in sections HDT1 and HDT2 are exothermic, a cold hydrogen quench can be used to moderate the temperature increase and control the reaction.

[0077] Isolated, lead-lag, series and / or parallel guard reactors can be considered depending on the nature and quantity of the contaminant in the flow to be treated.

[0078] In the event that the treatments of examples 1 or 2 do not allow sufficient reduction of impurities to be obtained, guard reactors for removing chlorine and silicon can be operated in the gas phase. The silicon can also be trapped on the upper bed of a reactor in section HDT2 or separately, upstream or downstream by the treatment of the hot gases leaving section HDT2.

[0079] Chlorine and mercury can be separated by liquid or gas phase guard reactors.

[0080] There may be intermediate quenches between the beds or between the HDT1 and HDT2 reactors or no quenching. In the latter case, recycling of part of the flow leaving HDT1 or HDT2 must be carried out to control the temperature. Strict control of the temperature in HDT1 must be carried out when this step is implemented, in order to avoid clogging of the reactor and degradation of the catalytic hydrogenation conditions.

[0081] The operating pressure in each of the hydrotreatments HDT1 and HDT2 is 5-140 bars, preferably 20-30 bars for HDT1 and 20-140 bars, preferably 30-100 bars for HDT2, typically 30-40 bars for HDT2.

[0082] Typical temperature range at the inlet of HDT1 at the start of the cycle (SOR: start of run): 150-200°C. The catalyst for HDT 1 usually comprises Pd (0.1-10% by weight) and / or Ni (0.1-60% by weight) and / or NiMo (0.1-60% by weight).

[0083] Typical temperature range at the inlet of HDT2 at the start of the cycle (SOR: start of run): 200-340°C. Typical temperature range at the outlet of HDT2 (SOR): 300-380°C, up to 450°C. The catalyst for HDT 2 usually comprises a NiMo (any type of commercial catalyst for refining or petrochemical application), potentially a CoMo in the very last beds at the bottom of the reactor (any type of commercial catalyst for refining or petrochemical application).

[0084] The upper bed of the HDT2 should preferably be operated with a NiMo having a hydrogenating capacity as well as a silicon trapping capacity. Such an upper bed can be considered as an adsorbent as well as a metal trap also having HDN activity and a hydrogenating capacity. An example of an upper bed acceptable for this function includes commercial NiMo catalyst adsorbents cialy available such as ACT971, ACT981 from Axens or equivalents from Haldor Topsoe, Axens, Criterion, etc. It is possible to have two separate beds in an HDT2 reactor, with quenching between the two beds or between the two reactors, if the two beds are in two separate reactors, or no quenching at all. Ideally, the intermediate quench is carried out using cold HDT2 effluent or by supplying cold hydrogen, i.e. at a temperature generally ranging from 15 to 30°C, in order to control the HDT2 exotherm. Dilution by recycling the hydrocarbon stream to the upper HDT2 bed is not recommended due to the increased risk of bed fouling. The feedstock arriving at the HDT2 catalyst should be completely vaporized at all times, including in variable regimes as is the case during start-ups.Sending liquid hydrocarbons to the upper bed of an HDT2 reactor can generate fouling and an increase in the pressure difference between the inlet and outlet of said HDT2 reactor and lead to premature shutdown.

[0085] Depending on the metals possibly present in the solid to be hydrotreated, a hydrodemetallization catalyst, for example commercial, can be added to the upper bed of the HDT2 section in order to protect the lower catalytic beds from deactivation.

[0086] The effluent leaving the HDT2 section may comprise 97% m / m or 98% m / m or more of paraffins, at most 2% m / m of olefins and may be used as such or fractionated according to distillation temperature ranges to obtain paraffins having a specific melting point meeting the specifications of a particular application, for example 70°C or more.

Claims

Claims

1. A process for producing paraffins by hydrotreatment from a composition comprising a plastic liquefaction oil, said composition comprising paraffins, olefins, aromatics and heteroatoms, the process comprising: (a) a step of separating a portion of the paraffins and olefins contained in said composition comprising at least one step of crystallizing (i) said composition by lowering the temperature from 10°C to 60°C from an initial temperature at which said composition is entirely liquid and obtaining a mixture comprising a solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms and an effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms, followed by at least one step of separating (ii) said solid product and said effluent,(b) a step of hydrotreatment of the solid product from step (a) during which the olefins contained in said solid product are hydrogenated and an effluent containing paraffins and at most 2% m / m of olefins is produced.,

2. Method according to claim 1, characterized in that, during the separation step (a), said composition is mixed with at least one solvent prior to the at least one crystallization step (i), the at least one solvent being in the liquid state and miscible with the composition at the temperatures for carrying out step (a).

3. A method according to claim 2, further comprising a step of separating the at least one solvent from the effluent from separation step (iii) and returning the at least one separated solvent to step (i).

4. Method according to claim 2 or 3, characterized in that the at least one solvent is an organic solvent.

5. Method according to claim 4, characterized in that the organic solvent is chosen from an aliphatic hydrocarbon, an aromatic hydrocarbon, a ketone, an alcohol or their mixtures.

6. Method according to claim 5, characterized in that the organic solvent is chosen from a ketone and an alcohol.

7. Method according to any one of claims 2 to 6, characterized in that the volume ratio of said composition to the solvent is from 10 / 90 v / v to 90 / 10 v / v, preferably 20 / 80 v / v to 80 / 20 v / v, more than preferably from 40 / 60v / v to 60 / 40v / v or from 45 / 55v / v to 55 / 45v / v.

8. Process according to any one of claims 1 to 7, characterized in that: the separation step (a) comprises: (i-1) a first crystallization step by lowering the temperature of said composition from 10°C to 60°C from a first initial temperature at which said composition is entirely liquid and obtaining a first mixture comprising a first solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms, and a first effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms, (ii-1) a first step of separating said first solid product and said first effluent,(i-2) a second crystallization step by lowering the temperature of said first effluent from 10°C to 60°C from a second initial temperature at which said first effluent is entirely liquid and obtaining a second mixture comprising a second solid product enriched in paraffins and depleted in olefins, aromatics and heteroatoms, and a second effluent depleted in paraffins and enriched in olefins, aromatics and heteroatoms, (ii-2) a second step of separating said second solid product and said second effluent, and the first solid product and the second solid product are subjected to hydrotreatment step (b).,

9. Method according to any one of claims 1 to 8, characterized in that the separation step (ii), (ii-1) or (ii-2) is carried out by at least one step chosen from filtration, decantation, centrifugation.

10. Process according to any one of claims 1 to 9, characterized in that the hydrotreatment of step (b) is carried out in a single step in which the solid product(s) resulting from step (a) are hydrogenated at a temperature of 200 to 450°C, preferably 200 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence of a hydrotreatment catalyst.

11. Process according to any one of claims 1 to 9, characterized in that the hydrotreatment of step (b) is carried out in a first step (b-1) in which the solid product(s) resulting from step (a) are hy- at a temperature of 80 to 250°C, preferably 130 to 190°C in the presence of hydrogen at an absolute pressure of 5 to 60 bars, preferably 20 to 30 bars and in the presence of a first hydrotreatment catalyst, and in a second step (b-2) in which the effluent from step (b-1) is hydrogenated at a temperature of 200 to 450°C, preferably 200 to 340°C in the presence of hydrogen at an absolute pressure of 20 to 140 bars, preferably 30 to 100 bars and in the presence of a second hydrotreatment catalyst.

12. Method for recovering plastic waste comprising the following steps: (A) a step of liquefying waste containing plastics and obtaining a hydrocarbon product comprising a gaseous phase, a liquid phase and a solid phase, (B) a step of separating the liquid phase from said product, said liquid phase forming a plastic liquefaction oil, (C) a step of treating at least a portion of the liquid phase by a paraffin production process according to any one of claims 1 to 11.