FR3126710A1 - Process for purifying hydrocarbon feedstock in aqueous medium and use - Google Patents

Abstract

Process for purifying a composition comprising a plastic pyrolysis oil comprising treatment with a strong base in the presence of water followed by washing with water. The process is useful for reducing the concentration of hetero-elements and in particular of alkali and alkaline-earth metal cations in said composition with a view to making it compatible for introduction as feedstock in conversion processes such as steam cracking, catalytic cracking in a fluidized bed, catalytic hydrogenation or hydrocracking, in particular without deactivating the catalysts used in these processes.

Description

Process for purifying hydrocarbon feedstock in aqueous medium and use

Technical field of the invention

The present invention relates to a process for the purification of hydrocarbon feedstock and its subsequent use in refining and petrochemical processes. The process according to the invention makes it possible to purify feedstocks containing plastic pyrolysis oils, in particular with a view to their use in a steam cracking process.

Technology background

Patent JP3776335 discloses a process for dechlorination and denitrogenation of an oil resulting from the catalytic or thermal cracking of plastic waste which is treated at different temperatures up to 425°C for 30 minutes in the presence of an aqueous solution of a compound alkali of an alkali or alkaline earth metal at a pH greater than or equal to 7. All non-radioactive natural alkali or alkaline earth metal hydroxides are tested. The reaction product is then separated from the alkaline aqueous solution by liquid-liquid separation with ethyl ether.

Patent application WO2012/069467 claims a process for eliminating siloxanes contained in a plastic pyrolysis oil by heat treatment between 200 and 350°C in the presence of an alkali metal hydroxide in the solid state or in solution. The use of calcium hydroxide at 5% by weight at 225°C does not make it possible to obtain a reduction in the siloxane content (table 5, p.12 and lines 9 to 11, p.13). At the end of the reaction, the pyrolysis oil is separated by distillation under reduced pressure.

Patent FI128848 describes a sequence of processes comprising heat treatment of a plastic pyrolysis oil at at least 200°C in the presence of an alkaline aqueous solution. At the end of the reaction, the pyrolysis oil is separated from the alkaline aqueous phase. A final hydrotreatment makes it possible to obtain a steam cracker charge which is optionally washed with an acid solution before introduction into the steam cracker.

Patent application WO2020/02769 claims a sequence of processes for purifying a composition comprising at least 20 ppm of chlorine. Many recyclable liquid wastes can be treated, including plastic pyrolysis oils. The process sequence comprises a heat treatment of the charge in the presence of an alkali metal hydroxide in order to obtain a reduction of at least 50% of the chlorine content with respect to the charge, followed by a hydrotreatment in order to obtain a new reduction of at least 50% of the chlorine content.

Patent application WO2021/105326 claims a process for recovering liquefied plastic waste comprising a step of pretreating the liquefied plastic waste by bringing it into contact with an aqueous medium having a pH of at least 7 at a temperature of 200°C or more. , followed by a liquid-liquid separation in which the aqueous phase is separated from the organic phase, to produce a pretreated liquefied waste plastic material. The proposed solution includes the use of a solution of NaOH in water. The separation of the aqueous and organic phases is carried out by physical (centrifugation) or chemical methods (addition of additives to aid separation, for example non-aqueous solvents, addition of an additional quantity of the aqueous medium used for setting in contact with or an aqueous medium having a different alkaline substance concentration), or by gravity.

These documents do not present means for lowering the content of alkali metals/alkaline earth metals present in the plastic pyrolysis oil after pretreatment with a strong base. However, it is known that the presence of alkali/alkaline earth metals can lead to the deactivation of catalysts used in catalytic processes for the treatment of pretreated plastic pyrolysis oil.

The aim of the invention is to propose a process for purifying plastic pyrolysis oil making it possible to facilitate its purification by limiting the quantity of strong base used while maintaining high reduction performance, including for the reduction of the content of alkali and/or alkaline-earth metals resulting from the treatment of plastic pyrolysis oil with a strong base.

To this end, the invention relates to a process for reducing the heteroatom concentration of a composition comprising a plastic pyrolysis oil containing at least 20 ppm by mass of chlorine as measured according to standard ASTM D7359-18, comprising:

(To). bringing said composition into contact with 0.1-50% by mass of a strong base comprising an alkali or alkaline-earth metal cation in the presence of water, for 1 minute to 20 minutes at a temperature of at most 450°C,

(b). washing with water at neutral or acidic pH of the product resulting from step (a).

In particular, step (a) is implemented without adding a solvent other than water or a solvent possibly already present in the composition.

Advantageously, the strong base added in step a) is in solution in water. Thus, during step (a), the composition can be brought into contact with an aqueous solution of a strong base comprising an alkali or alkaline-earth metal cation. The person skilled in the art will then choose a sufficient quantity of water to dissolve/solubilize the strong base, preferably the smallest possible quantity of water.

During step (a), the ratio by volume of the strong base in solution in water/composition, i.e. the ratio by volume of the mixture (strong base + water)/composition, may be 0.1/99 .9 to 80/20, from 1/99 to 80/20, from 1/99 to 70/30, from 1/99 to 65/35, from 1/99 to 60/40, from 1/99 to 50/ 50, or in any interval defined by any two of the aforementioned terminals.

The composition may further comprise a biomass pyrolysis oil such as Panicum virgatum , tall oil, used food oil, animal fat, vegetable oil such as rapeseed, canola, castor, palm, soya, an oil extracted from an algae, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, an oil from the pyrolysis of biomass such as a lignocellulosic biomass such as an oil from the pyrolysis of wood , paper and/or cardboard, an oil obtained by pyrolysis of crushed used furniture, an oil from the pyrolysis of elastomers, for example optionally vulcanized latex or tires, as well as mixtures thereof.

The composition may comprise at least 2% by mass of a plastic pyrolysis oil. The remainder may then be composed of at most 98% by mass of a diluent or solvent such as a hydrocarbon and/or of one or more of the components listed above. In one embodiment, the composition may comprise at least 25% by mass of pyrolysis plastic oil, preferably at least 50% by mass, more preferably 75% by mass, even more preferably at least 90% by mass of pyrolysis plastic oil. It is also possible to use only pyrolysis plastic oil.

The bringing into contact is preferably carried out for a period of 1 minute to 20 minutes, preferably from 1 minute to 16 minutes, at a temperature of 50 to 450° C., preferably of 90 to 350° C., more preferably of 150 to 350° C. and at an absolute pressure of 0.1 to 100 bar, preferably 1 to 50 bar.

A preferred strong base can be chosen from LiOH, NaOH, CsOH, Ba(OH) ₂ , Na ₂ O, KOH, K ₂ O, CaO, Ca(OH) ₂ , MgO, Mg(OH) ₂ and mixtures thereof. A more preferred strong base may be selected from NaOH, KOH and mixtures thereof.

The water used during step (b) can have an acid pH (PH<7) or neutral (pH=7). In particular, the water used does not contain a base and in particular does not contain a strong base comprising an alkali or alkaline-earth metal cation. An acid pH can be obtained by adding one or more organic or inorganic acids. Examples of usable organic acids include citric acid (C ₆ H ₈ O ₇ ), formic acid (CH₂O₂), acetic acid (CH₃COOH), sulfamic acid (H ₃ NSO ₃ ). Examples of inorganic acids are hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ).

Step (b) can be carried out at a temperature of 0° to 80°C, for example from 0° to 60°C, preferably from 0° to 40°C, more preferably from 0° to 30 °C, especially without external heating. Step (b) is typically carried out at atmospheric pressure.

During step (b), the water/composition volume ratio with the strong base may be from 10/90 to 90/10, from 20/80 to 80/20, from 30/70 to 70/30, from 35/65 to 65/35, from 35/65 to 60/40, from 40/60 to 60/40, or even within any interval defined by any two of the aforementioned limits.

Step (b) may comprise, or consist of, bringing the product resulting from step (a) into contact with water by any means known in the prior art.

For example, the product from step (a) and the water can be introduced into tanks, reactors or mixers commonly used in the profession and the two components can be mixed. Contacting may include vigorous agitation of the two components by a mixing device. For example, the two components can be mixed together by agitation or by shaking. Alternatively, the contacting can be carried out in an enclosure in which the two components circulate against the current. This contacting may occur more than once, in particular under the conditions presented above.

Step (b) can be implemented on the product directly resulting from step (a) (comprising the strong base in solution in water and the product resulting from bringing the composition into contact), without step intermediate, or on the product resulting from step (a) having undergone a separation step.

Thus, in one embodiment, the method according to the invention comprises, between step (a) and (b), a separation step between the strong base comprising the alkali or alkaline-earth metal cation in solution in the water and the product resulting from bringing said composition into contact. The product resulting from bringing said composition into contact corresponds to a composition comprising a plastic pyrolysis oil having a lower concentration of heteroatoms than the initial composition. It is thus a purified composition.

The separation between the strong base in solution in water and the product resulting from stage (a) is advantageously carried out by (i) centrifugation, (ii) decantation, or (iii) by the combination of these two stages.

Typically, this separation step makes it possible to separate an organic phase, corresponding to the product resulting from the contacting of step (a), and an aqueous phase containing the strong base comprising the alkali or alkaline-earth metal cation. It can be preceded by a solids separation step by (i) filtration, (ii) centrifugation or (iii) a combination of the two steps. This solids separation step can make it possible to facilitate the subsequent separation of the organic and aqueous phases by eliminating all or part of the solids present in the product resulting from step (a).

Also, advantageously, the strong base in solution in the water separated during this separation step can be returned (recycled), partially or totally, in step (a).

The separation step makes it possible to reduce part of the content of the product resulting from step (a) in alkaline or alkaline-earth cation. The remaining alkali or alkaline-earth cation content (or all or substantially all of the alkali or alkaline-earth cation content when this separation step is absent) is removed during washing step (b). The composition thus treated can be used without causing deactivation of catalysts used in subsequent catalytic treatment processes.

Washing step (b) can make it possible to obtain a product having an alkaline or alkaline-earth cation content of less than or equal to 2 ppm (by mass).

The invention may also comprise an additional step prior to step (a) of bringing into contact, in which said composition is subjected, in particular immediately before step (a), to (i) filtration, (ii) washing with a polar solvent, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). This preliminary step can make it possible to reduce some of the impurities contained in the composition, such as oxygen, nitrogen, chlorine, sulfur or other heteroatoms. In particular, the reduction in the quantity of oxygen can make it possible to avoid the formation of solids and/or gels during step (b).

During the additional preliminary washing step (ii), the polar solvent/composition volume ratio can be from 10/90 to 90/10, from 20/80 to 80/20, from 30/70 to 70/30, from 35/65 to 65/35, from 35/65 to 60/40, from 40/60 to 60/40.

The polar solvent can have a higher or lower density than the density of the composition comprising a plastic pyrolysis oil.

In particular, the density of the polar solvent can be higher or lower by 3 to 50% than that of the composition.

The polar solvent is also an immiscible solvent in the composition comprising a pyrolysis oil to be purified.

In the present invention, it may be considered that the polar solvent (or a mixture of polar solvents where appropriate) is immiscible when its recovery rate is greater than or equal to 0.95. This recovery rate is defined as the ratio of the volume of extract to the volume of initial solvent, this extract being a phase containing the solvent, immiscible with the composition containing a pyrolysis oil, recovered after agitation then decantation of a mixture one part by volume of solvent with twenty-five parts by volume of the composition containing a pyrolysis oil to be purified, at atmospheric pressure and at a temperature of 20°C.

In particular, this recovery rate can be determined by following the following procedure:

• Introduction of 50 mL of composition containing pyrolysis oil into a flat-bottomed flask with a volume of 100 mL, using a precision pipette of +/-0.5 mL,
• Introduce 2 mL of solvent into the flask, using a precision pipette +/-0.1mL,
• Introduce a magnetic bar, close the balloon with a polypropylene stopper,
• Shake the mixture on a mechanical stirrer plate at a speed of 500 rpm for 5 min,
• At the end of the 5 minutes, stop stirring, remove the magnetic bar using a magnetic rod,
• Transfer the contents of the flask into a graduated tube with an accuracy of +/-0.05 mL for a volume less than or equal to 2mL and an accuracy of +/-0.1 mL for a volume greater than 2mL. Wait for the complete demixing by decantation and measure the volume of the 2 phases using the graduations. It is considered that complete demixing is achieved when the volumes of the two phases no longer vary.

The expression "polar solvent" within the meaning of this patent application covers all the chemical species, alone or as a mixture, capable of solvating a composition comprising a plastic pyrolysis oil, and comprising at least one carbon-hydrogen covalent bond, carbon-halogen, carbon-chalcogen or carbon-nitrogen and having a non-zero dipole moment. The polar solvent can thus contain one or more heteroatoms, in particular chosen from oxygen, sulfur and nitrogen, preferably oxygen. Acceptable polar solvents, immiscible with the composition comprising a pyrolysis oil to be purified, include compositions comprising hydrocarbon compounds which contain heteroatoms in their molecular structure, for example (i) alcohols such as methanol and ethanol, and mixtures of alcohols resulting from fermentation, for example a mixture of isomers of butanol or a mixture of isomers of pentanol such as fusel oil (ii) ethers, for example cyclopentylmethyl ether or 1,4- dioxane, (iii) sulfur compounds, for example thiophene or dimethylsulfoxide, (iv) nitrogen compounds, for example N,N -dimethylformamide, (v) halogenated compounds, for example dichloromethane or chloroform, or else :

• water having an acidic, basic or neutral pH. An acid pH can be obtained by adding one or more organic or inorganic acids. Examples of usable organic acids include citric acid (C ₆ H ₈ O ₇ ), formic acid (CH₂O₂), acetic acid (CH₃COOH), sulfamic acid (H ₃ NSO ₃ ). Examples of inorganic acids are hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ). A basic pH can be obtained by adding alkali and alkaline-earth metal oxides, alkali and alkaline-earth hydroxides (for example NaOH, KOH, Ca(OH) ₂ ) and amines (for example triethylamine, ethylenediamine, ammonia).
• glycol ethers, including in particular polyethylene glycol of chemical formula HO-(CH ₂ -CH ₂ -O) _n -H with a mass-average molar mass of 90 to 800 g/mol, for example diethylene glycol and tetraethylene glycol, polypropylene glycol of chemical formula H[OCH(CH ₃ )CH ₂ ] _n OH with a mass-average molar mass of 130 to 800 g/mol, for example dipropylene glycol and tetrapropylene glycol,
• dialkyl formamides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethyl formamide (DMF),
• dialkyl sulfoxides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 carbon atoms, in particular dimethyl sulfoxide (DMSO) and sulfolane
• compounds comprising a furan ring,
• cyclic carbonate esters, comprising in particular from 3 to 8 or from 3 to 4 carbon atoms, in particular propylene carbonate and ethylene carbonate.

One or more of the aforementioned solvents can be used. However, advantageously, only one of the aforementioned solvents can be used provided that it is immiscible with the composition containing a pyrolysis oil to be purified.

Preferably, the polar solvent may be a glycol ether, in particular polyethylene glycol with the chemical formula HO-(CH ₂ -CH ₂ -O) _n -H with a mass-average molar mass of 90 to 800 g/mol or polypropylene glycol of chemical formula H[OCH(CH ₃ )CH ₂ ] _n OH with a mass-average molar mass of 130 to 800 g/mol, or a compound comprising a furan ring, or a cyclic carbonate ester, in particular propylene carbonate or ethylene, alone or as a mixture, preferably alone.

In a preferred embodiment, the polar solvent is chosen from propylene carbonate, ethylene carbonate and polyethylene glycol of chemical formula HO-(CH ₂ -CH ₂ -O) _n -H of mass-average molar mass from 90 to 800 g/mol, alone or as a mixture, preferably alone.

The invention may also include an additional step in which:

(vs). the product from the washing of step (b) undergoes catalytic hydrogenation in one or two stages.

In the case where the catalytic hydrogenation is carried out in two stages, stage (c) is carried out in a first stage (c-1) in which the product resulting from the contacting is hydrogenated at a temperature between 20 and 200° C., preferably between 30 and 90° C. in the presence of hydrogen at an absolute pressure of between 5 and 60 bars, preferably between 20 and 30 bars and in the presence of 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 (c-2) in which the effluent from the step (c-1) is hydrogenated at a temperature of between 200 and 450°C, preferably between 200 and 340°C in the presence of hydrogen at an absolute pressure of between 20 and 140 bar, preferably between 30 and 60 bars and in the presence of a hydrogenation catalyst comprising NiMo (0.1-60% by weight) and/or CoMo (0.1-60% by weight).

The product from step (b) or the effluent from step (c) is (d) preferably purified by passage through a solid adsorbent in order to reduce the content of at least one element from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or water content.

The adsorbent can be operated in regenerative or non-regenerative mode, at a temperature below 400°C, preferably below 100°C, more preferably below 60°C, chosen from: (i) a silica gel, ( ii) a clay, (iii) a crushed clay, (iv) apatite, (v) hydroxyapatite and combinations thereof, (vi) an alumina, for example an alumina obtained by precipitation of boehmite, a calcined alumina such such as Ceralox ® from Sasol, (vii) boehmite, (viii) bayerite, (ix) hydrotalcite, (x) a spinel such as Pural ® or Puralox from Sasol, (xi) a promoted alumina, by example Selexsorb ® from BASF, an acid promoted alumina, an alumina promoted by a zeolite and/or by a metal such as Ni, Co, Mo or a combination of at least two of them, (xii) a clay treated with an acid such as Tonsil ® from Clariant, (xiii) a molecular sieve in the form of an aluminosilicate containing an alkaline or alkaline-earth cation, for example sieves 3A, 4A, 5A, 13X, for example sold under the Siliporite ® brand of Ceca, (xiv) a zeolite, (xv) an activated carbon, or the combination of at least two adsorbents, the adsorbent or the at least two adsorbents retaining at least 20% by weight, preferably at least 50% by weight of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or water.

According to a preferred embodiment, the adsorbent is regenerable, has a specific surface of at least 200 m²/g and is operated in a fixed bed reactor at less than 100° C. with a VVH of 0.1 to 10 h ^-1 .

According to an additional embodiment, at least part of the product resulting from stage (b) or of the effluent resulting from stage (c) or (d) can be:

(e). processed in a steam cracker, and/or

(f). processed in a fluidized bed catalytic cracker, and/or

(g). processed in a hydrocracker, and/or

(h). treated in a catalytic hydrogenation unit, and/or

(i). used as such or separated into streams which can be used for the preparation of fuels and fuels such as LPG, petrol, diesel, heavy fuel oil and/or for the preparation of lubricants.

The previously described steps of the method according to the invention can be implemented one after the other without any intermediate step apart from the optional additional steps described.

Definitions

The hourly volume velocity (VVH) is defined as the hourly volume of feed flow per unit of catalytic volume and is expressed here in h ^-1 .

The terms "comprising" and "comprises" as used herein are synonymous with "including", "includes" or "contains", "containing", and are inclusive or without limitation and do not exclude additional features, unspecified elements or method steps.

Specifying a numeric domain without decimals includes all whole numbers and, where appropriate, fractions thereof (for example, 1 to 5 may include 1, 2, 3, 4, and 5 when referring to a count of items, and may also include 1.5, 2, 2.75, and 3.80, where reference is made to, for example, a measurement.).

Specifying a decimal also includes the decimal itself (for example, "from 1.0 to 5.0" includes 1.0 and 5.0). Any range of numeric values recited here also includes any subrange of numeric values mentioned above.

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 comprising it.

Unless otherwise specified, measurements given in parts per million (ppm) are by weight.

The expression "plastic pyrolysis oil" or "oil resulting from plastic pyrolysis" refers to the liquid products obtained after pyrolysis of thermoplastic, thermosetting or elastomeric polymers, alone or as a mixture and generally under the form of waste. The pyrolysis process must be understood as a thermal cracking process, implemented in the presence or not of a catalyst (for example fast pyrolysis, catalytic or not, etc.). The pyrolyzed plastic can be of any type. For example, the plastic to be pyrolyzed can be polyethylene, polypropylene, polystyrene, polyester, polyamide, polycarbonate, etc. These plastic pyrolysis oils contain paraffins, i-paraffins (iso-paraffins), dienes, alkynes, olefins, naphthenes and aromatics. Plastic pyrolysis oils also contain impurities such as chlorinated, oxygenated and/or silylated organic compounds, metals, salts, phosphorus compounds, sulfur, and nitrogen.

The composition of the plastic pyrolysis oil is dependent on the nature of the pyrolyzed 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 1 to 150 carbon atoms and impurities.

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

The expression “Number of bromine” corresponds to the quantity of bromine in grams having reacted on 100 g of sample and can be measured according to the ASTM D1159-07 method.

The term "Bromine Index" is the number of milligrams of bromine that reacts with 100 g of sample and can be measured by the methods ASTM D2710 or ASTM D5776.

Boiling points as mentioned herein are measured at atmospheric pressure, unless otherwise stated. An initial boiling point is defined as the temperature value from which a first bubble of vapor is formed. A final boiling point is the highest temperature reachable during distillation. At this temperature, no more vapor can be transported to a condenser. The determination of the initial and final points uses techniques known in the art and several methods adapted according to the range of distillation temperatures are applicable, for example NF EN 15199-1 (version 2020) or ASTM D2887 for the measurement of the points of boiling of petroleum fractions by gas chromatography, ASTM D7169 for heavy hydrocarbons, ASTM D7500, D86 or D1160 for distillates.

The concentration of metals in the 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). Specialists in analytical sciences know how to identify the most suitable method for measuring each metal and each hetero-element according to the hydrocarbon matrix considered.

The particular characteristics, structures, properties, embodiments of the invention can be freely combined in one or more embodiments not specifically described here, as may be apparent to specialists in the treatment of plastic pyrolysis oils implementing their general knowledge.

Description of the invention

Examples

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

Ex e simple 1 : Purification of one plastic pyrolysis oil in the presence of a strong base and water follow up e by washing with water

The physico-chemical characteristics of the plastic pyrolysis oil used are described in Table 1, below:

[Table 1] Table 1 Pyrolysis oil HPP2 Density (g/mL) 0.800 Kinematic viscosity (15°C, mm²/s) 2.1 Distillation, initial boiling point(°C) 69 Distillation, 50% (°C) 214 Distillation, end boiling point (°C) 451 Silicon (mass ppm) 82 Chlorine (ppm mass) 96 Oxygen (% mass) 0.87 Nitrogen (ppm weight) 206

Test protocol:

A 1.5 L AISI-316L grade stainless steel autoclave equipped with mechanical agitation is charged with the HPP2 pyrolysis oil, a strong base in the form of NaOH and water, the strong base being solubilized in water before entering the autoclave (Table 2). The sum of the volume of pyrolysis oil and the volume of water introduced is approximately 600 mL at ambient temperature, without taking into account any effects of volume variation during their mixing. The autoclave is closed and the gas overhead in the autoclave is swept with nitrogen for 30 minutes. The autoclave is then heated under autogenous pressure with stirring at a speed of 400 to 1500 rpm at a temperature of 225°C for a period of 1 minute, 10 minutes or 20 minutes depending on the tests, once the target temperature has been reached. The temperature rise rate is set at 30° C./10 minutes.

[Table 2] Table 2 Essay 1 2 3 Pyrolysis oil HPP2 HPP2 HPP2 Water/load volume ratio 0.024 0.024 0.024 Temperature (°C) 225 225 225 Time (mins) 1 10 20 Volume of water (mL) 13.8 13.8 138.0 Mass of NaOH (g) 14.0 14.0 138.0 Mass of pyrolysis oil (g) 467.2 467.2 368.0 Initial pyrolysis oil volume (mL) 584 584 460 NaOH concentration in pyrolysis oil (%m/m) 3 3 3 NaOH concentration in water (%m/m) 50 50 50 Initial density (g/mL) 0.8 0.8 0.8 Final pressure in the autoclave (bars) 10 8 12

At the end of the reaction, the autoclave is cooled to ambient temperature then, for tests 1 and 2, the mixture is discharged and washed three times with water with, at each wash, a water/ filler = 40/60, to remove strong base residues and water-soluble impurities. The resulting purified and washed pyrolysis oil is analyzed for residual impurity content (Table 3). For test 3, the mixture discharged from the autoclave is divided into two parts. The first part is washed with water under the same conditions as for tests 1 and 2 and the resulting purified and washed pyrolysis oil is analyzed (test 3A of table 3). The second part is decanted in order to recover the organic phase, which is then centrifuged. The resulting decanted and centrifuged pyrolysis oil is analyzed (test 3B of table 3).

[Table 3] Table 3 Essay 1 2 3A 3B Initial silicon (ppm weight) 80 80 80 80 Final silicon (ppm weight) <2 <2 <2 <2 Silicon abatement (%) >97 >97 >97 97 Initial chlorine (ppm weight) 115 115 115 115 Final chlorine (ppm weight) 32 24 23 23 Chlorine abatement (%) 72 79 80 80 Initial oxygen (% weight) 0.90 0.90 0.90 0.90 Final oxygen (% weight) 0.12 0.13 0.11 0.47 Oxygen abatement (%) 87 86 88 48 Initial nitrogen (ppm weight) 192 192 192 192 Final nitrogen (ppm weight) 31 29.8 30.0 43.6 Nitrogen reduction (%) 84 84 84 77 Initial sodium (ppm weight) <2 <2 2.5 <2 Final sodium (ppm weight) <2 <2 <2 1536

The data in Table 3 show that the use of soda in the presence of water followed by washing makes it possible to significantly reduce the impurities initially contained in the pyrolysis oil as well as the sodium introduced by the treatment with soda, even for a short duration of treatment with soda.

In particular, it has been observed that in the absence of washing, for example after simple decantation/centrifugation, the sodium content of the pyrolysis oil is high, in particular greater than 1000ppm, which is not acceptable for a treatment later catalytic.

The pyrolysis oil can either be used as it is, or optionally dried on an adsorbent such as a molecular sieve or an anhydrous salt, for example Na ₂ SO ₄ , then is distilled under reduced pressure in order to eliminate any possible trace solid, for example strong base, adsorbent residue, anhydrous/hydrated salt or gums.

Ex e simple 2 : Two-step hydrotreating and steam cracking of the product of Example 1

One of the purified and washed pyrolysis oils of example 1 (from tests 1, 2 or 3A) can be hydrotreated in two stages according to the following procedure:

The purified and washed pyrolysis oil can be introduced into a first hydrotreating section (HDT1) essentially to hydrogenate the diolefins and is operated in the liquid phase. This stage can 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 can make it possible to reduce the concentration of certain undesirable chemical species and/or of elements such as chlorine, silicon and metals. Particularly undesirable metals include Na, Ca, Mg, Fe and Hg.

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

Since the hydrotreating reactions in the HDT1 and HDT2 sections are exothermic, cold hydrogen quenching can be used to moderate the temperature rise and control the reaction.

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.

In the event that the treatment of example 1 does not make it possible to obtain a sufficient reduction in impurities, guard reactors to eliminate chlorine and silicon can be operated in the gaseous phase. The silicon can also be trapped on the upper bed of a reactor of the HDT2 section or separately, upstream or downstream by the treatment of the hot gases leaving the HDT2 section.

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

There may be intermediate quenches between the beds or between the HDT1 and HDT2 reactors or no quench. In the latter case, part of the flow leaving HDT1 or HDT2 must be recycled to control the temperature. A strict control of the temperature in HDT1 must be carried out, in order to avoid the clogging of the reactor and the deterioration of the catalytic hydrogenation conditions.

The operating pressure in each of the HDT1 and HDT2 hydrotreatments is 5-60 bars, preferably 20-30 bars for HDT1 and 20-140 bars, preferably 30-60 bars for HDT2, typically 30-40 bars for HDT2.

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

Typical temperature range at the HDT2 inlet at the start of the cycle (SOR: start of run): 200-340°C. Typical HDT2 output temperature range (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).

The upper bed of HDT2 should preferably be operated with a NiMo having a hydrogenating capacity as well as a silicon trapping capacity. An upper bed of this type can be considered as an adsorbent as well as a metal trap that also has HDN activity and hydrogenating capacity. An example of an upper bed acceptable for this function includes commercially available NiMo catalyst adsorbents 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 quenching is carried out using cold HDT2 effluent or by adding cold hydrogen, i.e. at a temperature generally ranging from 15 to 30°C, in order to control the exotherm of HDT2. Dilution by recycle of the hydrocarbon stream to the upper bed of HDT2 is not recommended due to the increased risk of bed fouling. The load arriving on the HDT2 catalyst should be completely vaporized at all times, including in variable speed as is the case during starts. 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 the outlet of said HDT2 reactor and lead to premature shutdown.

Depending on the metals present in the pyrolysis oil 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.

The hydrotreated pyrolysis oil leaving the HDT2 section can be used as it is or fractionated according to distillation temperature ranges, to supply a steam cracker, an FCC, a hydrocracker, a catalytic reformer or a pool of fuels or combustibles such as LPG, gasoline, jet, diesel, fuel oil.

Alternatively, the treated pyrolysis oil leaving the HDT2 section undergoes an additional purification step by passing it over a capture mass such as an adsorbent, for example (i) a silica gel, (ii) a clay, (iii) a crushed clay, (iv) apatite, (v) hydroxyapatite and combinations thereof, (vi) an alumina, for example an alumina obtained by precipitation of boehmite, a calcined alumina such as Ceralox ® from Sasol, (vii ) boehmite, (viii) bayerite, (ix) hydrotalcite, (x) a spinel such as Pural ® or Puralox from Sasol, (xi) a promoted alumina, for example Selexsorb ® from BASF, an alumina promoted acid, an alumina promoted by a zeolite and/or by a metal such as Ni, Co, Mo or a combination of at least two of them, (xii) an acid-treated clay such as Tonsil ® from Clariant , (xiii) a molecular sieve in the form of an aluminosilicate containing an alkaline or alkaline-earth cation, for example sieves 3A, 4A, 5A, 13X, for example marketed under the Siliporite ® brand from Ceca, (xiv) a zeolite , (xv) an activated carbon, or the combination of at least two adsorbents, the adsorbent or the at least two adsorbents retaining at least 20% by weight, preferably at least 50% by weight of at least one element among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or water. Ideally, the adsorbent is regenerable, has a specific surface of at least 200 m²/g and is operated in a fixed bed reactor at less than 100° C. with a VVH of 0.1 to 10 h ^-1 .

Claims (15)

Process for reducing the heteroatom concentration of a composition comprising a plastic pyrolysis oil containing at least 20 ppm by mass of chlorine as measured according to standard ASTM D7359-18, comprising:

1. bringing said composition into contact with 0.1-50% by mass of a strong base comprising an alkali or alkaline-earth metal cation, in the presence of water, for 1 minute to 20 minutes at a temperature of at over 450°C,
2. washing with water at neutral or acidic pH of the product resulting from step (a).

A method according to claim 1, wherein the composition further comprises biomass pyrolysis oil such as Panicum virgatum , tall oil, used cooking oil, animal fat, vegetable oil such as rapeseed oil, canola, castor, palm, soy, an oil extracted from an algae, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeasts, a biomass pyrolysis oil such as a lignocellulosic biomass such as an oil from the pyrolysis of wood, paper and/or cardboard, an oil obtained by pyrolysis of crushed used furniture, an oil from the pyrolysis of elastomers, for example possibly vulcanized latex or tires, as well as mixtures thereof. Process according to claim 1 or 2, comprising between step (a) and (b) a step of separation between the strong base comprising the alkali or alkaline-earth metal cation in solution in water and the product resulting from the bringing said composition into contact. Process according to claim 3, in which the separation step is carried out by (i) centrifugation, (ii) decantation, or (iii) by the combination of these two steps. Process according to Claim 3 or 4, in which the strong base in solution in water separated during the separation stage is returned, partially or totally, to the contacting stage (a). Process according to one of Claims 3 to 5, in which the stage of separation is preceded by a stage of separation of the solids by (i) filtration, (ii) centrifugation or (iii) a combination of the two stages. Process according to any one of Claims 1 to 6, in which the bringing into contact is carried out for a period of 1 minute to 20 minutes, preferably from 1 minute to 16 minutes, at a temperature of 50 to 450°C, preferably 90 to 350°C, more preferably 150 to 350°C and at an absolute pressure of 0.1 to 100 bar, preferably 1 to 50 bar. Process according to any one of Claims 1 to 7, in which the strong base is chosen from LiOH, NaOH, CsOH, Ba(OH) ₂ , Na ₂ O, KOH, K ₂ O, CaO, Ca(OH) ₂ , MgO, Mg(OH) ₂ and their mixtures. Process according to any one of Claims 1 to 8, in which, prior to the contacting of step (a), the said composition is subjected to (i) filtration, (ii) washing with a polar solvent, (iii) distillation, (iv) decantation, or (v) the combination of two, three or four of steps (i) to (iv). Process according to one of Claims 1 to 9, in which:
(c) the product resulting from the washing of stage (b) undergoes catalytic hydrogenation in one or two stages. Process according to Claim 10, in which the catalytic hydrogenation of stage (c) is carried out in a first stage (c-1) in which the product resulting from the placing in contact is hydrogenated at a temperature comprised between 20 and 200° C., preferably between 30 and 90° C. in the presence of hydrogen at an absolute pressure of between 5 and 60 bars, preferably between 20 and 30 bars and in the presence of 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 (c-2) in which the effluent from step (c-1) is hydrogenated at a temperature of between 200 and 450° C., preferably between 200 and 340° C. in the presence of hydrogen at an absolute pressure of between 20 and 140 bars, preferably between 30 and 60 bars and in the presence of a hydrogenation catalyst comprising NiMo (0.1-60% by weight) and/or CoMo (0.1-60% by weight). Process according to any one of Claims 1 to 11, in which the product resulting from stage (b) or the effluent resulting from stage (c) is (d) purified by passage through a solid adsorbent in order to reduce the content of at least one element from among F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or the water content. Process according to Claim 12, in which the adsorbent is operated in regenerative or non-regenerative mode, at a temperature below 400°C, preferably below 100°C, more preferably below 60°C chosen from: (i) a silica gel, (ii) a clay, (iii) a crushed clay, (iv) apatite, (v) hydroxyapatite and combinations thereof, (vi) an alumina, for example an alumina obtained by precipitation of boehmite, a calcined alumina such as Ceralox ® from Sasol, (vii) boehmite, (viii) bayerite, (ix) hydrotalcite, (x) a spinel such as Pural ® or Puralox from Sasol, (xi ) a promoted alumina, for example Selexsorb® from BASF, an acid promoted alumina, an alumina promoted by a zeolite and/or by a metal such as Ni, Co, Mo or a combination of at least two of them, ( xii) an acid treated clay such as Tonsil ® from Clariant, (xiii) a molecular sieve in the form of an aluminosilicate containing an alkali or alkaline earth cation e.g. 3A, 4A, 5A, 13X sieves, e.g. marketed under the Siliporite ® brand from Ceca, (xiv) a zeolite, (xv) an activated carbon, or the combination of at least two adsorbents, the adsorbent or the at least two adsorbents retaining at least 20% by weight, of preferably at least 50% by weight of at least one element from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or some water. Process according to Claim 13, in which the adsorbent is regenerable, has a specific surface area of at least 200 m²/g and is operated in a fixed bed reactor at less than 100°C with a VVH of 0.1 to 10 h ^-1 . Process according to any one of claims 1 to 14, in which at least part of the product resulting from stage (b) or of the effluent resulting from stage (c) or (d) is:
(e) processed in a steam cracker, and/or
(f) processed in a fluidized bed catalytic cracker, and/or
(g) treated in a hydrocracker, and/or
(h) treated in a catalytic hydrogenation unit, and/or
(i) used as such or separated into streams which can be used for the preparation of fuels and combustibles such as LPG, petrol, diesel, heavy fuel oil and/or for the preparation of lubricants.