FR3141185A1 - Process for treating a composition comprising an oil derived from plastic waste - Google Patents

Abstract

Process for treating a composition comprising an oil from plastic waste The present invention relates to a process for treating a composition comprising an oil from liquefied plastics, said composition containing at least 5 ppm by mass of silicon and/or at least 2 ppm by mass of chlorine as measured according to the ISO20884 standard, said treatment process comprising: a) a step of bringing said composition into contact, under heat, with a strong base; then c) a washing step with a polar solvent immiscible with the product obtained, said polar solvent being chosen from water, a polar organic solvent and their mixtures; then d) a step of mixing the product of the previous step with a petroleum product comprising at least one petroleum distillation fraction, the mixture obtained comprising between 1% by mass and 98% by mass of the product of the previous step; then e) a catalytic hydrotreatment step, in the presence of hydrogen, of the mixture obtained in the previous step. Figure: none

Description

Process for treating a composition comprising an oil derived from plastic waste

The present invention relates to a process for treating a composition comprising a liquefied plastic oil, in particular produced from plastic waste.

The chemical recycling of plastic material, for example by pyrolysis, allows the recovery of this type of waste. The material is thermally decomposed to yield a hydrocarbon oil containing various impurities, including compounds including metals and/or heteroatoms, such as silicon, chlorine, nitrogen and oxygen.

It is advantageous to treat oils from plastic waste with the aim of using them as fuel, for example for thermal engines.

For this purpose, hydrotreatments, or hydrorefinings, refer to catalytic treatment processes in the presence of hydrogen, preferably hot and/or under pressure. Hydrotreatments make it possible to eliminate many impurities such as unsaturated hydrocarbons, metals and compounds comprising heteroatoms. Hydrotreatments are in particular part of the known processes for refining petroleum cuts for the manufacture of fuels, as described for example in document WO2014/096704.

However, certain impurities present in oils from plastic waste cause deactivation of the catalysts used during hydrotreatments and/or operational problems such as fouling and corrosion. Among these impurities we find, among others, chlorine and silicon, in particular in the form of siloxanes.

In order to refine oils from plastic waste using a classic hydrotreatment process, it is possible to mix these oils beforehand with a petroleum product such as a petroleum distillation cut. This type of process is known as co-processing.

To limit deactivation of hydroprocessing catalysts and operational problems in existing processes/units, the quantity of oil mixed with a petroleum product generally does not exceed 1% to 2% by mass. Such a constraint strongly limits the prospects for recycling oils from plastic waste.

Applications FR 21 04616, FR 21 04617 and FR 21 09395, not yet published, in the name of the Applicant, describe a process for purifying plastic pyrolysis oils prior to a steam cracking step. This purification process makes it possible to drastically reduce the content of compounds comprising heteroatoms and silicon in these oils.

The present invention aims to feed the oils thus purified into hydrotreatment processes mixed with petroleum products.

To this end, the subject of the invention is a treatment process of the aforementioned type, in which: the composition comprising a liquefied plastics oil contains at least 5 ppm by mass of silicon as measured according to the ISO20884 standard and/or at least 2 ppm by mass of chlorine as measured according to ASTM D7359; and the method comprises the following steps:

a) a step of bringing the composition into contact, under heat, with a strong base; Then

c) a washing step with a polar solvent immiscible with the product obtained, said polar solvent being chosen from water, a polar organic solvent and their mixtures; Then

d) a step of mixing the product of the previous step with a petroleum product comprising at least one petroleum distillation fraction, the mixture obtained comprising between 1% by mass and 98% by mass of the product of the previous step; Then

e) a catalytic hydrotreatment step, in the presence of hydrogen, of the mixture obtained in the previous step.

In this description, the term “liquefied plastic oil” refers to liquid products obtained following treatment of thermoplastic, thermosetting or elastomeric polymers, alone or in mixture and generally in the form of waste. The treatment is for example pyrolysis or HTL (HydroThermal Liquefaction) treatment. The treated plastic is, for example, polyethylene, polypropylene, polystyrene, polyester, polyamide, polycarbonate or mixtures thereof.

Pyrolysis is a thermal cracking process, carried out in the presence or absence of a catalyst.

The composition of liquefied plastic oil depends on the nature of the plastic processed and is formed, typically more than 80% by mass, of hydrocarbons having 1 to 150 carbon atoms. Liquefied plastic oils contain in particular compounds such as paraffins, iso-paraffins, dienes, alkynes, olefins, naphthenes and aromatics.

Liquefied plastic oils also contain impurities such as chlorinated, oxygenated and/or silylated organic compounds, metals, salts, phosphorus compounds, sulfur, and nitrogen.

According to an advantageous embodiment, the composition comprising a liquefied plastics oil comprises at least 25% by weight of liquefied plastics oil, preferably at least 50% by weight of liquefied plastics oil, more preferably at least 90% by weight of oil liquefied plastics. According to a particular embodiment, the composition comprises only a liquefied plastic oil.

According to an advantageous embodiment, the composition comprising a liquefied plastic oil further comprises an oil derived from biomass. Said oil from biomass is for example chosen from: a Panicum virgatum oil, a tall oil (from the paper mill), a used food oil, an animal fat, a vegetable oil such as rapeseed oil, canola oil , castor, palm, soya, 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 a oil for pyrolysis of wood, paper and/or cardboard, an oil obtained by pyrolysis of crushed used furniture, an oil for pyrolysis of elastomers, for example possibly vulcanized latex or tires, as well as their mixtures.

In the present description, it is considered that the composition subjected to the process of the invention initially contains at least 5 ppm by mass of silicon, as measured according to the ISO20884 standard, and/or at least 2 ppm by mass of chlorine as measured. according to ASTM D7359. Silicon is notably present in liquefied plastic oils in the form of siloxanes, in particular cyclic siloxanes of type D3, D4 and/or D5. Chlorine is particularly present in liquefied plastic oils in the form of inorganic chlorine, but also organic chlorine such as chloroethane, dichloroethane, chlorobenzene or even vinyl chloride.

According to an advantageous embodiment, the strong base of contacting step a) comprises an oxide, a hydroxide, a bicarbonate or an alkoxide of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or in a mixture. More preferably, 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 , NH ₄ OH , TMAOH, TEAOH, TBuOH, MeONa, EtONa and their mixtures. Even more preferably, the strong base is chosen from KOH, NaOH and their mixtures.

Alternatively, the strong base is chosen from Na ₂ O, K ₂ O, CaO, MgO and their mixtures with each other and/or with the hydroxide bases previously mentioned.

An example of estimating a minimum quantity of strong base to use in step a) will be described later.

According to an advantageous embodiment, step a) of contacting is carried out at a temperature of at least 85°C, preferably at least 100°C, more preferably at least 150°C, even more preferably at least 180°C.

Preferably, step a) of contacting is carried out at a pressure of between 1 bar and 50 bars, more preferably between 1 bar and 30 bars, even more preferably between 1 bar and 25 bars.

The duration of contacting step a) is preferably at least 1 minute, more preferably between 5 minutes and 2 hours, even more preferably between 10 minutes and 1 hour.

According to a first advantageous embodiment, contacting step a) is carried out in the presence of water. Preferably, step a) is carried out in the presence of a concentrated aqueous solution of the strong base, more preferably in the presence of a saturated aqueous solution of the strong base.

According to a second advantageous embodiment, contacting step a) is carried out in the presence of a polar organic solvent comprising an alcohol function and/or an ether function. Preferably, said polar organic solvent is chosen from (i) C1 to C4 alcohols, preferably from methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol ethylene glycol, propylene glycol, (ii) alcohols comprising an ether function, preferably diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol and (iii) cyclic ethers, preferably tetrahydrofuran, 2-methyltetrahydrofuran, cyclopentylmethylether, tetrahydropyran, 1,4-dioxane, eucalyptol; and their mixtures.

The term “polar organic solvent” within the meaning of this description covers all chemical species, alone or in mixture, capable of solvating a composition comprising a liquefied plastic oil, and comprising at least one covalent carbon-hydrogen, carbon-halogen bond. , carbon-chalcogen or carbon-nitrogen and having a non-zero dipole moment.

According to a third advantageous embodiment, the strong base of contacting step a) is in solid form, for example in the form of soda pellets.

According to one embodiment, the treatment process comprises, between steps a) and c), a step b) of separation of the composition from the strong base.

Said separation step b) is implemented by any method known to those skilled in the art, including centrifugation, decantation, filtration or by the combination of these methods.

Preferably, if the treatment process is implemented in a reactor, the strong base recovered in step b) is recycled at the head of said reactor for step a).

In the first and second advantageous embodiments described above for step a), separation step b) makes it possible to separate a first so-called oily liquid phase, corresponding to the product resulting from step a), and a second liquid phase containing most of the strong base. According to the third advantageous embodiment described above for step a), separation step b) makes it possible to separate a liquid phase, corresponding to the product resulting from step a), and a solid phase, comprising essential of the strong base.

According to an alternative embodiment, the mixture formed by the composition and the strong base in step a) is directly subjected to washing step c). The omission of step b) is for example advantageous in the case of a strong base quantity chosen in slight excess compared to the minimum quantity, the method of calculation of which is described later.

In the present description, in particular concerning washing step c), it is considered that a polar solvent is immiscible with the product resulting from step b) when its recovery rate is greater than or equal to 0.95. The 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 liquefied plastic oil, recovered after stirring then decanting a mixture of one part by volume of solvent with twenty-five parts by volume of the composition containing a liquefied plastic oil to be purified, at atmospheric pressure and a temperature of 20°C. A method for determining the recovery rate is for example described in application FR2109395 cited above.

According to one embodiment in which the polar solvent of washing step c) comprises a polar organic solvent, said polar organic solvent is advantageously chosen from (i) 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 800g/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, (ii) dialkyl formamides, in which the alkyl group can comprise from 1 to 8 or from 1 to 3 atoms of carbons, in particular N,N -dimethyl formamide (DMF), (iii) 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, (iv) compounds comprising a furan ring, (v) cyclic carbonate esters, comprising in particular from 3 to 8 or from 3 to 4 carbon atoms, in particular propylene carbonate and ethylene carbonate; and their mixtures.

According to an advantageous embodiment, the polar solvent of washing step c) is water with a neutral pH (pH=7) or acidic (pH<7). Preferably, said water does not contain a base and in particular a hydroxide base. The acidic pH of water is for example 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 ).

According to an advantageous embodiment, during washing step c), a polar solvent/composition volume ratio is between 10/90 and 90/10, preferably between 20/80 and 80/20, more preferably between between 30/70 and 70/30, even more preferably between 40/60 and 60/40.

According to an advantageous embodiment, washing step c) is carried out at a temperature between 0°C and 120°C, preferably between 10°C and 90°C, more preferably at room temperature.

Preferably, washing step c) is carried out at a pressure of between 1 bar and 50 bars, more preferably between 1 bar and 30 bars, more preferably between 1 bar and 10 bars, even more preferably at atmospheric pressure.

Washing step c) is for example carried out by stirring the product from step a) or b) and the washing solvent in the same container, or by counter-current circulation. The duration of step c) is preferably at least 1 minute, more preferably between 1 minute and 10 minutes.

Advantageously, washing step c) is repeated several times, for example two or three times, with identical or different solvents.

Steps a) to c) make it possible to significantly reduce the silicon and/or chlorine content of the composition comprising the liquefied plastic oil. In particular, according to numerous experimental results, the silicon content of the composition resulting from step c) is less than 2 ppm by mass, for an initial value of between 9 ppm and 150 ppm.

According to one embodiment, before mixing step d), the product resulting from washing step c) is subjected to an additional drying step on an adsorbent such as Na ₂ SO ₄ and/or distillation and/or or any other means to extract free water.

During mixing step d), the product from washing step c) is mixed with a petroleum product comprising at least one petroleum cut, that is to say at least one petroleum distillation fraction. Preferably, the petroleum product consists of one or more petroleum distillation fractions.

Said one or more petroleum distillation fractions are preferably chosen from the following cuts or mixtures of cuts, characterized by their start and end temperatures of distillation. Said temperatures, given as an indication, correspond to distillation at atmospheric pressure:

- a naphtha/gasoline cut, whose start of distillation temperature is less than 45°C and the end of distillation temperature is between 145°C and 180°C;

- a naphtha/gasoline-LPG cut, comprising a naphtha cut as defined above and further comprising C3 and C4 alkanes, of the propane and butane type;

- a kerosene cut, whose start temperature of distillation is between 145°C and 180°C and the end temperature of distillation is between 240°C and 300°C;

- a diesel cut, whose start of distillation temperature is between 225°C and 250°C and the end of distillation temperature is between 360°C and 380°C;

- a mixed kerosene-diesel cut, whose start of distillation temperature is between 145°C and 180°C and the end of distillation temperature is between 360°C and 380°C;

- an atmospheric residue, which includes distillation products at temperatures greater than or equal to 360°C.

Preferably, the petroleum product introduced in step d) comprises only one/one of the cuts or mixtures of cuts described above, and not several of these cuts or mixtures of cuts.

According to an advantageous embodiment, the product resulting from step c) undergoes a distillation step f) before being mixed in step d) with a petroleum product. Distillation step f) is carried out with start and end distillation temperatures close to the start and end distillation temperatures of the petroleum product in step d). Preferably, the start and end temperatures of distillation of step f) are equal to the start and end temperatures of distillation of the petroleum product.

The mixture produced in step d) comprises between 1% by mass and 98% by mass of the product of the previous step, i.e. step c) or f).

The percentage by mass of the product obtained in said step c) or f) in the mixture obtained in step d) is preferably at least 3%, more preferably at least 5%, more preferably at least 10 %, more preferably at least 15% and even more preferably at least 20%.

In the case where the product of step c) has not undergone step f) of distillation before mixing with the petroleum product, said distillation can be carried out on the mixture of step d) before putting it into operation. work of step e).

Indeed, as will be described below, the implementation characteristics of step e) of catalytic hydrotreatment preferentially depend on the characteristics of the petroleum product introduced in step d), in particular on its starting temperatures and end of distillation.

Step e) is a hydrotreatment step, or hydrorefining, of the mixture obtained in the previous step. Hydrotreatment step e) is a catalytic treatment step in the presence of hydrogen or dihydrogen (H ₂ ), of the mixture obtained in step d), said mixture possibly then having been distilled, as indicated above.

More precisely, step e) is a hydrotreatment step aimed at eliminating all or part of the sulfur, nitrogen, oxygen compounds, and other impurities present in the mixture obtained in step d). Hydrotreatment includes, among other things, hydrodesulfurization (or HDS), hydrodenitrogenation (or HDN), hydrodeoxygenation (HDO), hydrogenation (HYD), hydrodearomatization or hydrodemetallation (HDM) reactions.

Hydrotreatment step e) is preferably carried out in a reactor, which is considered in the description which follows.

The hydrotreatment catalysts used are preferably supported catalysts comprising an oxide support and at least one hydrogenating function. Such catalysts are known from the state of the art.

Preferably, these catalysts may be catalysts containing at least one element from group VIB (Cr, Mo, W) and/or an element from group VIII (Fe, Ru, Os, Co, Rh, Ir, Pd, Ni, Pt ). More preferably, these catalysts are sulfur type catalysts containing at least one element from group VIB (Cr, Mo, W) and/or one element from group VIII (Fe, Co, Ni).

Preferably, the catalyst of step e) comprises a sulfur type catalyst based on cobalt-molybdenum CoMo and/or nickel-molybdenum NiMo and/or NiW, or a mixture of these catalysts.

The oxide support is for example chosen from the group consisting of alumina, silica, silica-aluminas, zirconia, titanium oxide, clays and mixtures of at least two of these minerals. Advantageously, this support may contain other doping compounds, such as boron, phosphorus, or a mixture of these dopants.

Preferably, step e) is carried out hot and/or under pressure. In particular, step e) is carried out at a temperature between 200°C and 450°C, preferably between 250 and 420°C, more preferably between 250°C and 400C; and at an absolute pressure between 5 and 200 bars, preferably between 5 and 80 bars, more preferably between 20 and 60 bars.

The spatial velocity of the feed, called LHSV, which is defined as the volumetric flow rate of liquid hydrocarbon feed divided by the total volume of catalyst, can be between 0.5 and 5 h ^-1 , preferably from 1 to 4 h ^-1 . The quantity of hydrogen mixed with the feed, defined as the ratio between the volumetric flow rate of hydrogen measured under normal conditions of temperature and pressure by the volumetric flow rate of liquid hydrocarbon feed, can be between 100 and 1600 Nm³/m³ , preferably between 100 and 800 Nm³/m³, more preferably between 200 and 600 Nm³/m³.

For example, step e) is implemented in a fixed bed reactor, comprising one or more catalytic beds, each bed comprising at least one hydrotreatment catalyst. The reactor is supplied on the one hand by a flow of the mixture obtained in step d), and on the other hand by a gaseous flow rich in hydrogen, in a manner similar to the hydrodesulfurization step described in document WO2014/ 096704.

Optionally, one or more pretreatment steps or sections may be used upstream of hydrodesulfurization (HDS). The aim of this pre-treatment step(s), called hydrodemetallation (HDM), is to eliminate the majority of the metals in the feed or other impurities using one or more hydrodemetallation catalysts. To do this, a succession of catalysts presenting a different porosity between the HDM section and the HDS section can be used, making it possible to optimize at each stage, the accessibility of the active phase, the porosity and the active phase content, manner similar to what is described in document US2006/0060509 for example. In this case, the HDM catalysts used are preferably catalysts known to those skilled in the art. They generally comprise a metal component from Group VIB, preferably molybdenum, on a porous oxide support, generally alumina used alone or mixed with other oxides such as silicon, titanium or zirconia. The catalyst may also contain or not a Group VIII metal component, preferably nickel and/or cobalt, for reasons of economy and performance, preferably nickel. The hydrodemetallization catalyst may contain limited amounts of other ingredients known to those skilled in the art, such as phosphorus, boron, alkali metal components and alkaline earth metal components. The porosity of the support of the catalysts considered can then either be a large average porous distribution or a bimodal porous distribution combining mesopores allowing the surface area to be maximized and macropores allowing the diffusion of large molecules, as described in patents US7119045 or EP1060794 .

Alternatively, demetallation reactions in the presence of hydrogen are carried out in separate reactors, before hydrotreatment step e).

Preferably, the implementation characteristics of step e) of catalytic hydrotreatment depend on the characteristics of the petroleum product introduced in step d). In particular, step e) is preferably carried out on known catalytic hydrotreatment units, intended for the refining of specific petroleum cuts or specific mixtures such as naphtha/gasoline, naphtha/gasoline-LPG, kerosene, gasoil, kerosene cuts. -diesel and atmospheric residue described above.

It is therefore preferable that the petroleum product introduced in step d) contains only one/one of these cuts or mixtures of cuts. Likewise, it is preferable that the composition mixed in step d) of said petroleum product has previously undergone step f) of distillation, or alternatively that the mixture obtained in step d) is distilled before step e ) with the appropriate start and end temperatures of distillation.

The low silicon and chlorine content of the product obtained in step c) makes it possible to mix step d) with a significant proportion of liquefied plastic oil, without impacting the hydrotreatment catalyst(s) during step e).

The product obtained at the end of step e) is intended to be used as fuel. According to one embodiment, said product of step e) is then subjected to an additive step suitable for said use as fuel. Additives such as corrosion inhibitors, antioxidants, anti-foaming agents, demulsifiers and/or chelants are for example added to the product of step e).

The process described above thus allows efficient recycling of liquefied plastic oils, among other things in the form of fuel.

Examples of embodiment of the invention

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

Example 1: Calculation of a minimum quantity of strong base to be brought into contact with the liquefied plastic oil composition in step a)

A minimum quantity of strong base to be used during step a) can in particular be estimated as follows:

Let a be the mass percentage of oxygen and let b, c and d be the respective contents in parts per million for nitrogen, chlorine and silicon, in the composition to be treated.

Let A, B, C and D be the respective molar masses of oxygen, nitrogen, chlorine and silicon.

Let M be the molar mass of the strong base to be used (around 40 g/mol for sodium hydroxide) and m be a percentage linked to the consumption of strong base.

This last value is calculated as follows:

Assuming that not all heteroatoms react with the strong base, as may be the case with a carboxylic acid which will consume one equivalent of base for two oxygen atoms, the minimum mass concentration of α base is calculated as next :

where ε is a factor being at least equal to 0.5.

Example 2 : Purification of a plastic pyrolysis oil in the presence of a strong base and water followed by washing with water

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

[Table 1] Table 1 Pyrolysis oil HPP4 Density (g/mL) 0.826 Kinematic viscosity (15°C, mm²/s) 2.78 Distillation, initial boiling point (°C) 84 Distillation, 50% (°C) 233 Distillation, final boiling point (°C) 398 Silicon (mass ppm) 45 Chlorine (mass ppm) 164 Oxygen (% by mass) 1.69 Nitrogen (ppm weight) 3510

Test protocol:

A 1.5 L AISI-316L grade stainless steel autoclave equipped with mechanical stirring is charged with HPP4 pyrolysis oil, a strong base in the form of NaOH and water, the strong base being solubilized in water before its introduction into the autoclave (table 2). The sum of the volume of pyrolysis oil and the volume of water introduced is approximately 600 mL at room temperature, without taking into account the possible effects of volume variation during their mixing. The autoclave is closed and the gaseous sky in the autoclave is flushed 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 30 minutes, once the target temperature has been reached. The temperature rise speed is set at 30°C/10 minutes.

[Table 2] Table 2 Essay 1 Pyrolysis oil HPP4 Water/load volume ratio 0.025 Temperature (°C) 225 Time (min) 30 Water volume (mL) 14.5 Mass of NaOH (g) 14.5 Mass of pyrolysis oil (g) 481 Initial volume of pyrolysis oil (mL) 584 NaOH concentration in pyrolysis oil (%m/m) 3 NaOH concentration in water (%m/m) 50 Initial density (g/mL) 0.824 Final pressure in the autoclave (bars) 13

At the end of the reaction, the autoclave is cooled to room temperature then the mixture is unloaded and washed three times with water with, at each wash, a water/charge volume ratio = 40/60, for remove strong base residue and water-soluble impurities. The resulting purified and washed pyrolysis oil is analyzed to measure the content of residual impurities (Table 3).

[Table 3] Table 3 Essay 1 Initial silicon (ppm weight) 45 Final silicon (ppm weight) <2 Silicon reduction (%) >95 Initial chlorine (ppm weight) 164 Final chlorine (ppm weight) 16 Chlorine reduction (%) 90 Initial oxygen (% weight) 1.69 Final oxygen (% weight) 0.38 Oxygen reduction (%) 78 Initial nitrogen (ppm weight) 3510 Final nitrogen (ppm weight) 881 Nitrogen reduction (%) 75 Initial sodium (ppm weight) <2 Final sodium (ppm weight) <2

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 soda treatment.

The pyrolysis oil is either used as 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 of solid, for example strong base, adsorbent residue, anhydrous/hydrated salt or gums.

Example 3 : Mixture of the product in the example 2 with a petroleum product

We consider an SGRO (Straight Run Gas Oil) type petroleum product having the following characteristics (table 4):

[Table 4] Table 4 OPE 7028 Density (g/mL) 0.8575 ASTM D86 – T5% (°C) 255 ASTM D86 – T95% (°C) 370 Total nitrogen (ppm mass) 160 Sulfur (ppm mass) 11000

The silicon and chlorine contents of SGRO are considered to be negligible.

We consider the mixtures below of said SGRO with the product of step 2 (treated HPP4) or with the initial untreated HPP4 (HPP4), depending on their silicon and chlorine levels (table 5). The mixtures are expressed as a mass percentage of HPP4, treated or not. The “HDS Specification” column corresponds to the maximum admissible values of silicon and chlorine levels in a product, before passing through an industrial catalytic hydrodesulfurization reactor:

[Table 5] Table 5 Levels (ppm) HDS specification SGRO + 2% HPP4 SGRO + 2% HPP4 treated SGRO + 10% HPP4 SGRO + 10% HPP4 treated If < 1 0.9 << 1 4.5 << 1 Cl <2 3.3 0.3 16.4 1.6

The treatment process according to the invention for HPP4 oil makes it possible to introduce it up to 10% by mass into a mixture with SGRO, while satisfying the requirements for the catalytic hydrodesulfurization step.

On the contrary, in the absence of treatment according to the invention, the 10% HPP4 mixture exceeds the specifications for silicon and chlorine, and the 2% HPP4 mixture exceeds the specifications for chlorine.

The treatment process according to the invention therefore makes it possible to increase the quantity of oil resulting from recycling of plastics in mixtures with petroleum products, in particular intended to produce fuels.

Claims (12)

Process for treating a composition comprising a liquefied plastic oil, said composition containing at least 5 ppm by mass of silicon as measured according to the ISO20884 standard, and/or at least 2 ppm by mass of chlorine as measured according to the ASTM D7359 standard, said treatment process comprising:
a) a step of bringing said composition into contact, under heat, with a strong base; Then
c) a washing step with a polar solvent immiscible with the product obtained, said polar solvent being chosen from water, a polar organic solvent and their mixtures; Then
d) a step of mixing the product of the previous step with a petroleum product comprising at least one petroleum distillation fraction, the mixture obtained comprising between 1% by mass and 98% by mass of the product of the previous step; Then
e) a catalytic hydrotreatment step, in the presence of hydrogen, of the mixture obtained in the previous step. A treatment method according to claim 1, wherein the strong base of step a) comprises an oxide, hydroxide, bicarbonate or alkoxide of an alkali metal cation or an alkaline earth metal cation, or a hydroxide or a bicarbonate of a quaternary ammonium cation, alone or in a mixture. Treatment process according to claim 1 or claim 2, comprising, before step c), a step b) of separating the composition with the strong base. Treatment method according to one of the preceding claims, in which the polar solvent of step c) is water at neutral or acidic pH. Treatment method according to one of the preceding claims, in which step a) is carried out in the presence of water, preferably in the presence of a concentrated aqueous solution of the strong base, more preferably in the presence of a saturated aqueous solution from the strong base. Treatment method according to one of claims 1 to 4, in which step a) is carried out in the presence of a polar organic solvent comprising an alcohol function and/or an ether function. Method according to one of claims 1 to 4, in which the strong base of step a) is in solid form. Treatment method according to one of the preceding claims, in which step a) is carried out at a temperature of at least 85°C, preferably at least 100°C, more preferably at least 150°C, even more preferably at least 180°C. Treatment method according to one of the preceding claims, in which: the petroleum product of mixing step d) is characterized by start and end temperatures of distillation; and before mixing step d), the product obtained in step c) undergoes a distillation step f), with start and end temperatures of distillation similar to the start and end temperatures of distillation of said petroleum product . Treatment method according to one of the preceding claims, in which the mixture obtained in step d) comprises at least 3% by mass, preferably at least 5% by mass, more preferably at least 10% by mass, more preferably at least 15% by mass, even more preferably at least 20% by mass, of the product obtained in the previous step. Treatment method according to one of the preceding claims, in which the composition comprising a liquefied plastics oil further comprises a biomass oil. Treatment process according to one of the preceding claims, then comprising a step of adding additives to the product obtained in step e) of catalytic hydrotreatment, so as to make said product suitable for use as fuel.