Patent Application
20240376388
The present invention relates to a method for purifying a hydrocarbon feedstock and its subsequent use in refining and petrochemical processes. The method according to the invention allows to purify feedstocks containing plastic pyrolysis oils and/or oils of hydrothermal liquefaction of plastic in particular with a view to their use in a steam cracking method.
The patent JP3776335 discloses a method for dechlorinating and denitrifying an oil coming from the catalytic or thermal cracking of plastic waste that is treated at various temperatures up to 425° C. for 30 minutes in the presence of an aqueous solution of an alkaline compound of an alkali or alkaline earth metal at a pH greater than or equal to 7. All the hydroxides of non-radioactive natural alkali or alkaline earth metals are tested. The reaction product is then separated from the alkaline aqueous solution by liquid-liquid separation with ethyl ether.
The patent application WO2012/069467 claims a method for eliminating siloxanes contained in a plastic pyrolysis oil by heat treatment between 20° 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 allow to obtain a reduction in the siloxane content (table 5, p. 12 and lines 9 to 11, p. 13). After the reaction, the pyrolysis oil is separated by distillation at a reduced pressure.
The patent FI128848 describes a method sequence comprising a heat treatment of a plastic pyrolysis oil at at least 200° C. in the presence of an alkaline aqueous solution. After the reaction, the pyrolysis oil is separated from the alkaline aqueous phase. A final hydrotreatment allows to obtain a steam cracker feedstock that is optionally washed by an acid solution before introduction into the steam cracker.
The patent application WO2020/020769 claims a method sequence for purifying a composition comprising at least 20 ppm of chlorine. Numerous recyclable liquid wastes can be treated, including plastic pyrolysis oils. The method sequence comprises a heat treatment of the feedstock 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 feedstock, followed by a hydrotreatment in order to obtain a new reduction of at least 50% of the chlorine content.
The patent application WO2021/105326 claims a method for reusing liquefied plastic waste comprising a step of pretreatment of the liquefied plastic waste by placing it in 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 plastic material of pretreated liquefied waste. The solution proposed comprises the use of a solution of NaOH in water. The separation of the aqueous and organic phases is implemented by physical (centrifugation) or chemical (addition of additives for assisting the separation, for example non-aqueous solvents, addition of an additional quantity of aqueous medium used for placing in contact or of an aqueous medium having a concentration of a different alkaline substance) methods, or by gravity.
The patent application US20140303421A1 describes a method for treating synthetic crude oils allowing to lower the concent of acids and/or the presence of particles and of contaminants containing heteroatoms. The synthetic crude oil is washed with a basic aqueous solution having a pH no higher than 10 in order to avoid saponification. The synthetic crude oil is then separated from the aqueous solution. In the embodiment illustrated by FIG. 3, the synthetic crude oil is washed with a first solution in order to eliminate the particles, the contaminants containing metals or metalloids or alkali metals. For this purpose, the first solution is acidic to neutralise the alkali species and absorb the acids or metals, metalloids of the organic polar molecules or other impurities and/or the first solution contains chelating agents to eliminate the metals. The synthetic crude oil thus washed is then separated then washed with a second basic aqueous solution having a pH not higher than 10 before being once again separated.
The patent application WO2020239729 describes a method for purifying plastic pyrolysis oils that comprises a purification step in which the oil is subjected to a hydrothermal treatment at 150-450° C. with water or water at pH>7. The oil is then separated from the aqueous phase then sent without other intermediate treatment to hydrotreatment, alone or in a mixture, in the presence of a catalyst and hydrogen in order to carry out one or more reactions of hydrogenation, hydrodeoxygenation, hydrodesulphurisation, hydrodenitrification, hydrodechlorination, hydrodearomatisation or hydroisomerisation.
These documents do not present means for lowering the content of alkali/alkaline earth metals present in the plastic pyrolysis oil and/or in the oil of hydrothermal liquefaction of plastic after pretreatment by a strong base. However, it is known that the presence of alkali/alkaline earth metals can lead to the deactivation of catalysts used in the catalytic methods for treatment of pretreated plastic oil.
The invention aims to propose a method for purifying plastic liquefaction oil allowing 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 the plastic liquefaction oil by a strong base.
For this purpose, the invention relates to a method for reducing the concentration of heteroatoms in a composition comprising a plastic liquefaction oil containing at least 20 ppm by weight of chlorine as measured according to the standard ASTM D7359-18, comprising:
The plastic liquefaction oil can be a plastic pyrolysis oil, an oil of hydrothermal liquefaction of plastic or a mixture of the two, for example a plastic pyrolysis oil.
In particular, step (a) is implemented without addition of solvent other than the water or a solvent optionally already present in the composition.
During step (a), the composition is placed in contact with 0.1 to 50% by weight of a strong base with respect to the weight of the composition introduced.
Advantageously, during step (a), the composition is placed in contact with 0.1 to 15% by weight of a strong base in the presence of water, more preferably with 1 to 15% by weight of a strong base, even more preferably with 1 to 10% by weight of a strong base.
Advantageously, the strong base added in step (a) is in solution in water. Thus, during step (a), the composition can be placed in contact with an aqueous solution of a strong base comprising an alkali or alkaline earth metal cation. A person skilled in the art will thus choose quantity of water sufficient to dissolve/solubilise the strong base, preferably the smallest possible quantity of water, or just enough to saturate the water with strong base.
Advantageously, the strong base added in step (a) is in solution in the water, and the content of strong base in the water is 0.1 to 50% by weight, preferably 25% to 50% by weight, more preferably 40 to 50% by weight, even more preferably, the water is saturated with strong base, in particular the water contains a quantity of strong base just sufficient to obtain a saturated solution.
During step (a), the volume ratio of the strong base in solution in the water/composition, i.e. the volume ratio of the mixture (strong base+water)/composition, can be from 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 the entire interval defined by any two of the aforementioned limits.
The composition can further comprise an oil of pyrolysis or of hydrothermal liquefaction of biomass, in particular an oil of pyrolysis or of hydrothermal liquefaction of biomass such as of Panicum virgatum, a tall oil, a used food oil, an animal fat, a vegetable oil such as a colza, canola, ricin, palm, soybean oil, an oil extracted from an alga, an oil extracted from a fermentation of oleaginous microorganisms such as oleaginous yeast, an oil of pyrolysis or of hydrothermal liquefaction of biomass such as a lignocellulosic biomass such as an oil of pyrolysis of wood, of paper and/or of cardboard, an oil obtained by pyrolysis or hydrothermal liquefaction of ground used furniture, an oil of pyrolysis or hydrothermal liquefaction of elastomers for example of optionally vulcanised latex or of tires, as well as mixtures thereof.
The composition can comprise at least 2% by weight of a plastic oil, or even at least 1% by weight of plastic oil. The rest can thus be composed of at most 98% by weight, or even of at most 99% by weight of a dilutant or solvent such as a hydrocarbon and/or of one or more of the components listed above. In one embodiment, the composition can comprise at least 5% m, preferably at least 10% m, more preferably at least 25% by weight of plastic oil, preferably at least 50% by weight, more preferably 75% by weight, even more preferably at least 90% by weight of plastic oil. The composition can comprise at most 80% m or 90% m or 95% m or 100% m of plastic liquefaction oil. It is also possible to use only plastic oil.
The placing in contact preferably occurs for a duration of 1 minute to 20 minutes, preferably 1 minute to 16 minutes, at a temperature of 50 to 450° C., preferably 50 to 350° C. or 90 to 350° C., more preferably 150 to 350° C., even more preferably 50 to 250° C., 50 to 225° C. or 50 to 200° C., and at an absolute pressure of 0.1 to 100 bar, preferably 1 to 50 bar. It should be noted that the duration of placing in contact can be longer (for example from 30 minutes to 1 hour, or even more), but does not allow to improve the quality of the products obtained.
In a particularly preferred embodiment, the placing in contact is carried out for a duration of 1 minute to 20 minutes, preferably 1 minute to 16 minutes, at a temperature of at most 250° C., more preferably of at most 225° C., even more preferably of at most 200° C. In this particularly preferred embodiment, the placing in contact can be carried out at a temperature of at least 50° C., preferably of at least 90° C., more preferably of at least 150° C. In this particularly preferred embodiment, the placing in contact can be carried out at an absolute pressure of 0.1 to 100 bar, preferably 1 to 50 bar.
In this particularly preferred embodiment, the composition can advantageously be placed in contact with:
A preferred strong base can be chosen from LiOH, NaOH, CsOH, Ba(OH)2, Na2O, KOH, K2O, CaO, Ca(OH)2, MgO, Mg(OH)2 and mixtures thereof. A more preferred strong base can be chosen from NaOH, KOH and mixtures thereof, in particular for the implementation of the particularly preferred embodiment.
The water used during step (b) can have an acidic (pH<7) or neutral (pH=7) pH. 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 acidic pH can be obtained by adding one or more organic or inorganic acids. Examples of usable organic acids comprise citric acid (C6H8O7), formic acid (CH2O2), acetic acid (CH3COOH). Examples of inorganic acids are hydrochloric acid (HCl), nitric acid (HNO3), sulphuric acid (H2SO4), phosphoric acid (H3PO4), sulphamic acid (H3NSO3).
Step (b) can be carried out at a temperature of 0° to 80° C., for example 0° to 60° C., preferably 0° to 40° C., more preferably 0° to 30° C., in particular without external heating. Step (b) is typically implemented at atmospheric pressure.
During step (b), the volume ratio of water/composition with the strong base can be 10/90 to 90/10, 20/80 to 80/20, 30/70 to 70/30, 35/65 to 65/35, 35/65 to 60/40, 40/60 to 60/40, or in any interval defined by any two of the aforementioned limits.
Step (b) can comprise, or consist of, placing the product coming from step (a) in contact with water by any means known in the prior art.
For example, the product coming from step (a) and the water can be introduced into tanks, reactors or mixers routinely used in the profession and the two components can be mixed. The placing in contact can comprise vigorous stirring of the two components by a mixing device. For example, the two components can be mixed together by stirring or by shaking. Alternatively, the placing in contact can be carried out in a chamber in which the two components circulate counter-current. This placing in contact can occur more than once, in particular in the conditions presented above.
Step (b) can be implemented on the product directly coming from step (a) (comprising the strong base in solution in the water and the product coming from placing the composition in contact), without an intermediate step, or on the product coming 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 step of separation between the strong base comprising the alkali or alkaline earth metal cation in solution in the water and the product coming from placing said composition in contact. The product coming from placing said composition in contact corresponds to a composition comprising a plastic pyrolysis oil having a concentration of heteroatoms lower than the initial composition. This is therefore a purified composition.
The separation between the strong base in solution in the water and the product coming from step (a) is advantageously carried out by (i) centrifugation, (ii) decantation, or (iii) by the combination of these two steps.
Typically, this separation step allows to separate an organic phase, corresponding to the product coming from the placing in contact 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 step of separating the solids by (i) filtration, (ii) centrifugation or (iii) a combination of the two steps. This step of separating the solids can allow to facilitate the separation of the later organic and aqueous phases by eliminating all or a part of the solids present in the product coming from step (a).
Also, advantageously, the strong base in solution in the water separated during this separation step can be sent back (recycled), partly or in totality, into step (a).
The separation step allows to lower a part of the content of alkali or alkaline earth cation in the product coming from step (a). The remaining content of alkali or alkaline earth cation (or the totality or quasi-totality of the content of alkali or alkaline earth cation when this separation step is absent) is eliminated during the washing step (b). The composition thus treated can be used without causing a deactivation of catalysts used in catalytic processes of later treatments.
The washing step (b) can allow to obtain a product having a content of alkali or alkaline earth cation lower than or equal to 2 ppm (by weight).
The invention can also comprise an additional step prior the step (a) of placing in contact, in which said composition is subjected, in particular immediately before step (a), to (i) a filtration, (ii) washing with a polar solvent, (iii) a distillation, (iv) a decantation, or (v) to the combination of two, three of four of steps (i) to (iv). This prior step can allow to lower a part of the impurities contained in the composition such as oxygen, nitrogen, chlorine, sulphur or other heteroatoms. In particular the reduction in the quantity of oxygen can allow to avoid the formation of a solid and/or of gels during step (b).
During the prior additional step of washing (ii), the volume ratio of polar solvent/composition can be 10/90 to 90/10, 20/80 to 80/20, 30/70 to 70/30, 35/65 to 65/35, 35/65 to 60/40, 40/60 to 60/40.
The polar solvent can have a density higher or lower than the density of the composition comprising a plastic oil, in particular 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 further a solvent non-miscible in the composition comprising a pyrolysis oil to be purified.
In the present invention, it can be considered that the polar solvent (or that a mixture of polar solvents if necessary) is non-miscible 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, non-miscible with the composition containing a pyrolysis oil, recovered after stirring then decantation of a mixture of 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.
This recovery rate can in particular be determined by following the following procedure:
The expression “polar solvent” in the sense of the present patent application covers all the chemical species, alone or in a mixture, capable of solvating a composition comprising a plastic oil, in particular a plastic pyrolysis oil, and including at least one carbon-hydrogen, carbon-halogen, carbon-chalcogen or carbon-nitrogen covalent bond and having a non-zero dipole moment. The polar solvent can thus contain one or more heteroatoms, in particular chosen from oxygen, sulphur and nitrogen, preferably oxygen. Acceptable polar solvents, non-miscible with the composition comprising a plastic oil to be purified, include compositions comprising hydrocarbon compounds that include heteroatoms in their molecular structure, for example (i) alcohols such as methanol and ethanol, and mixtures of alcohols coming from fermentation, for example a mixture of isomers of butanol or a mixture of isomers of pentanol such as a fusel oil, (ii) ethers, for example cyclopentyl methyl ether or 1,4-dioxane, (iii) sulphurated compounds, for example thiophene or dimethylsulphoxide, (iv) nitrogenated compounds, for example N,N-dimethylformamide, (v) halogenated compounds, for example dichloromethane or chloroform, or:
One or more of the aforementioned solvents can be used. However, advantageously, just one of the aforementioned solvents can be used provided that it is non-miscible with the composition containing a plastic oil, in particular a plastic pyrolysis oil, to be purified.
Preferably, the polar solvent can be a glycol ether, in particular the polyethylene glycol having the chemical formula HO—(CH2—CH2—O)n—H having a mass average molar mass of 90 to 800 g/mol or the polypropylene glycol having the chemical formula H[OCH(CH3)CH2]nOH having a mass average molar mass of 130 to 800 g/mol, or a compound comprising a furane cycle, or a cyclic carbonate ester, in particular the carbonate of propylene or of ethylene, alone or in a mixture, preferably alone.
In a preferred embodiment, the polar solvent is chosen from propylene carbonate, ethylene carbonate and the polyethylene glycol having the chemical formula HO—(CH2—CH2—O)n—H having a mass average molar mass of 90 to 800 g/mol, alone or in a mixture, preferably alone.
The invention can also comprise an additional step in which:
In the case in which the catalytic hydrogenation is carried out in two steps, step (c) is carried out in a first step (c-1) in which the product coming from the placing in contact is hydrogenated at a temperature of between 2° and 200° C., preferably between 3° and 90° C. in the presence of hydrogen at an absolute pressure of between 5 and 60 bar, preferably between 20 and 30 bar 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 coming from step (c-1) is hydrogenated at a temperature of between 20° and 450° C., preferably between 20° and 340° C. in the presence of hydrogen at an absolute pressure of between 20 and 140 bar, preferably between 30 and 60 bar 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 coming from step (b) or the effluent coming from step (c) is (d) preferably purified by passing over a solid adsorbent in order to reduce the content of at least one element out of F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or the content of water.
The adsorbent can be used in regenerative or non-regenerative mode, at a temperature lower than 400° C., preferably lower than 100° C., more preferably lower than 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 calcinated 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 acidic 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 alkali or alkaline earth cation for example the sieves 3A, 4A, 5A, 13X, for example marketed under the brand Siliporite® 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 out of F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or of the water.
According to a preferred embodiment, the adsorbent is regenerative, has a specific surface area of at least 200 m2/g and is used in a fixed-bed reactor at less than 100° C. with an SV of 0.1 to 10 h−1.
According to an additional embodiment, at least a part of the product coming from step (b) or of the effluent coming from step (c) or (d) can be:
The steps described above of the method according to the invention can be implemented one after the other without an intermediate step besides the optional additional steps described.
The space velocity (SV) is defined as the hourly volume of stock flow per unit of catalytic volume and is expressed here in h−1.
The terms “comprising” and “comprises” as used here are synonyms with “including”, “includes” or “contains”, “containing”, and are inclusive or without limits and do not exclude non-specified additional features, elements or steps of methods.
The specification of a numerical range without decimals includes all the integers and, when this is appropriate, fractions of the latter (for example, 1 to 5 can include 1, 2, 3, 4 and 5 when reference is made of a number of elements, and can also include 1.5, 2, 2.75 and 3.80 when reference is made to, for example, a measurement).
The specification of a decimal also comprises the decimal itself (for example, “from 1.0 to 5.0” includes 1.0 and 5.0). Any range of numerical values mentioned here also comprises any sub-range of numerical 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 100 g of a composition comprising it.
Unless otherwise indicated, the measurements given in parts per million (ppm) are expressed by weight.
The expression “plastic liquefaction oil” or “liquefied plastic oil” or “plastic oil” designates the liquid products resulting from the pyrolysis of the plastic and/or from the hydrothermal liquefaction of plastic, alone or in a mixture and generally in the form of plastic waste, optionally mixed with at least one other waste such as biomass, for example chosen from lignocellulosic biomass, paper and cardboard and/or elastomers, for example optionally vulcanised latex or tires.
The biomass can be defined as a plant or animal organic product, including residues and organic waste. The biomass thus comprises (i) the biomass produced by the surplus of agricultural land, not used for human or animal food: dedicated crops, called energy crops; (ii) the biomass produced by tree clearing (forest maintenance) or the clearing of agricultural land; (iii) the agricultural residues coming from cereal cultures, grape vines, orchards, olive trees, fruits and vegetables, residues from the agri-food industry, etc.; (iv) the forest residues coming from sylviculture and from the transformation of wood; (v) the agricultural residues coming from livestock farming (manure, liquid manure, litter, droppings, etc.); (vi) household organic waste (paper, cardboard, green waste, etc.); (vii) non-hazardous industrial organic waste (papers, cardboard, wood, putrescible waste, etc.). The liquefaction oil treated by the invention can be derived from the liquefaction of waste containing at least 1% m/m, optionally 1-50% m/m, 2-30% m/m, or in a range defined by two of these limits, of one or more of the aforementioned biomasses, residues and organic wastes, and the rest consisting of plastic waste, optionally mixed with elastomers, in particular in the form of waste.
The elastomers are linear or branched polymers transformed by vulcanisation into an infusible and insoluble weakly cross-linked three-dimensional network. They include the natural or synthetic rubbers. They can be part of waste of the tire type or any other household or industrial waste containing elastomers, natural and/or synthetic rubber, mixed or not with other components, such as plastics, plasticisers, fillers, vulcanising agents, vulcanisation accelerators, additives, etc. Examples of elastomer polymers include the ethylene-propylene copolymers, ethylene-propylene-diene terpolymer (EPDM), polyisoprene (naturel or synthetic), polybutadiene, the styrene-butadiene copolymers, the polymers containing isobutene, the copolymers of isobutylene isoprene, chlorinated or brominated, the copolymers of butadiene acrylonitrile (NBR), and the polychloroprenes (CR), the polyurethanes, the elastomers of silicone, etc. The plastic liquefaction oil treated by the invention can 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 an interval defined by any two of these limits, of one or more aforementioned elastomers, in particular in the form of waste, the rest consisting of plastic waste, optionally mixed with biomasses, residues and organic waste.
The expression “plastic pyrolysis oil” or “oil resulting from the pyrolysis of plastic” refers to the liquid products obtained after a pyrolysis of thermoplastic, thermosetting or elastomer polymers, alone or in a mixture and generally in the form of waste. The pyrolysis method must be understood as a method for thermal cracking, typically carried out at a temperature of 300 to 1000° C. or 400 to 700° C., implemented in the presence of a catalyst or not (for example fast catalytic pyrolysis or not, etc.).
The expression “hydrothermal plastic oil” or “oil resulting from the hydrothermal liquefaction of plastic” designates the liquid products obtained after hydrothermal liquefaction of plastic or of plastic waste. The method for hydrothermal liquefaction is typically carried out at a temperature of 250 to 500° C. and at pressures of 10 to 25-40 MPa in the presence of water.
The pyrolysed plastic or plastic resulting from hydrothermal liquefaction can be of any type. For example, the plastic can be polyethylene, polypropylene, polystyrene, a polyester, a polyamide, a polycarbonate, etc. These plastic liquefaction oils contain paraffins, i-paraffins (iso-paraffins), dienes, alkynes, olefins, naphthenes and aromatics. The plastic liquefaction oils also contain impurities such as chlorinated, oxygenated and/or silylated organic compounds, metals, salts, phosphorus compounds, sulphur, and nitrogen.
The composition of the plastic pyrolysis oil or of the oil of hydrothermal liquefaction of plastic depends on the nature of the plastic pyrolysed or treated by hydrothermal liquefaction and substantially consists (in particular at more than 80% m/m, most often at more than 90% m/m) of hydrocarbons having from 1 to 150 carbon atoms and of impurities.
A plastic liquefaction oil typically comprises from 5 to 80% m/m of paraffins (including cyclo-paraffins), from 10 to 95% m/m of unsaturated compounds (comprising olefins, dienes and acetylenes), from 5 to 70% m/m of aromatics. These contents can be determined by gas chromatography.
A plastic liquefaction oil can in particular comprise one or more of the following contents of heteroatoms: from 0 to 8% m/m of oxygen (measured according to the standard ASTM D5622), from 1 to 13000 ppm of nitrogen (measured according to the standard ASTM D4629), from 2 to 10000 ppm of sulphur (measured according to the standard ISO 20846), from 1 to 10000 ppm of metals (measured by ICP), from 50 to 6000 ppm of chlorine (measured according to the standard ASTM D7359-18), from 0 to 200 ppm of bromine (measured according to the standard ASTM D7359-18), from 1 to 40 ppm of fluorine (measured according to the standard ASTM D7359-18), 1 to 2000 ppm of silicon (measured by XRF).
The expression “MAV” (acronym of “Maleic Anhydric Value”) refers to the method UOP326-82 which is expressed in mg of maleic anhydride that react with 1 g of sample to be measured.
The expression “bromine number” corresponds to the quantity of bromine in grams having reacted over 100 g of sample and can be measured according to the method ASTM D1159-07.
The expression “bromine index” is the number of milligrams of bromine that react with 100 g of sample and can be measured according to the methods ASTM D2710 or ASTM D5776.
The boiling points as mentioned here are measured at atmospheric pressure, unless otherwise indicated. An initial boiling point is defined as the temperature value starting at which a first bubble of vapour is formed. A final boiling point is the highest temperature reachable during a distillation. At this temperature, no more vapour can be transported towards a condenser. The determination of the initial and final boiling points uses techniques known in the field 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 boiling points 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 spectroscopy (ICP-AES). The specialists in analytical sciences know how to identify the method most adapted to the measurement of each metal and each hetero-element according to the hydrocarbon matrix considered.
The specific features, structures, properties, embodiments of the invention can be combined freely in one or more embodiments not specifically described here, as can be clear to specialists in the treatment of plastic pyrolysis oils implementing their general knowledge.
The embodiments of the present invention are illustrated by the following non-limiting examples.
The physico-chemical characteristics of the plastic pyrolysis oil used are described in table 1, below:
A 1.5 L autoclave made of AISI-316L grade stainless steel equipped with mechanical stirring is loaded with the pyrolysis oil HPP2, a strong base in the form of NaOH and water, the strong base being dissolved in the water before its introduction into the autoclave (table 2). The sum of the volume of pyrolysis oil and of the volume of water introduced is approximately 600 mL at ambient temperature, without taking into account the possible effects of variation in volume during their mixture. The autoclave is closed and the headspace 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 duration of 1 minute, 10 minutes or 20 minutes according to the trials, once the target temperature has been reached. The speed of temperature rise is set to 30° C./10 minutes.
After the reaction, the autoclave is cooled to ambient temperature then, for trials 1 and 2, the mixture is unloaded and washed three times with water with, at each washing, a volume ratio of water/feedstock=40/60, to eliminate the residues of strong base and the impurities soluble in water. The resulting purified and washed pyrolysis oil is analysed to measure the content of residual impurities (table 3). For trial 3, the mixture unloaded from the autoclave is divided into two parts. The first part is washed with water in the same conditions as for trials 1 and 2 and the resulting purified and washed pyrolysis oil is analysed (trial 3A in 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 analysed (trial 3B in table 3).
The data of table 3 shows that the use of sodium hydroxide in the presence of water followed by washing allows to considerably reduce the impurities initially contained in the pyrolysis oil as well as the sodium introduced by the treatment with sodium hydroxide, even for a short duration of treatment with sodium hydroxide.
In particular, it was observed that in the absence of washing, for example after a simple decantation/centrifugation, the content of sodium in the pyrolysis oil is high, in particular greater than 1000 ppm, which is not acceptable for a later catalytic treatment.
The pyrolysis oil can be either used as such, or optionally dried on an adsorbent such as a molecular sieve or an anhydride salt, for example Na2SO4, then is distilled under reduced pressure in order to eliminate any possible trace of solid, for example of strong base, of adsorbent residue, of anhydride/hydrated salt or of gums.
Another pyrolysis oil HPP8 was placed in contact with sodium hydroxide according to a trial protocol similar to that of example 1 in conditions gathered together in table 4. 450 g of HPP8 oil were thus placed in contact for 20 minutes at 180° C. with 22.5 g of NaOH dissolved in water.
After the reaction, the autoclave is cooled to ambient temperature, then the mixture is unloaded and washed three times with water with, at each washing, a volume ratio of water/feedstock=40/60, to eliminate the residues of strong base and the impurities soluble in water.
The data of table 5 shows that the use of sodium hydroxide in the presence of water followed by washing allows to considerably reduce the impurities initially contained in the pyrolysis oil as well as the sodium introduced by the treatment with sodium hydroxide, even for a temperature of treatment with sodium hydroxide lower than 200° C.
One of the purified and washed pyrolysis oils of example 1 (coming from trials 1, 2 or 3A) or of example 2 (trial 4) can be hydrotreated in two steps according to the following procedure:
The purified and washed pyrolysis oil can be introduced into a first hydrotreatment section (HDT1) substantially to hydrogenate the diolefins and is operated in liquid phase. This step 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 allow to reduce the concentration of certain undesirable chemical species and/or of elements such as chlorine, silicon and the metals. Particularly undesirable metals include Na, Ca, Mg, Fe and Hg.
A second hydrotreatment section (HDT2) is dedicated to the hydrogenation of the olefins and to demetallation (HDM), desulphurisation (HDS), denitrification (HDN) and deoxygenation (HDO). HDT2 is operated in gas phase. This section consists of one or more reactors operated in series, lead-lad or parallel.
Since the hydrotreatment reactions in the sections HDT1 and HDT2 are exothermal, a quenching with cold hydrogen can be used to moderate the temperature increase and control the reaction.
Insulated guard reactors, in lead-lag, series and/or parallel are possible according to the nature and the quantity of the contaminant in the flow to be treated.
In the hypothesis in which the treatment of example 1 does not allow to obtain a sufficient reduction in impurities, guard reactors to eliminate the chlorine and the silicon can be operated in gas phase. The silicon can thus be trapped on the upper bed of a reactor of the section HDT2 or separately, upstream or downstream by the treatment of the hot gases exiting the section HDT2.
The chlorine and the mercury can be separated by guard reactors in liquid or gas phase.
There can be intermediate quenchings between the beds or between the reactors HDT1 and HDT2 or no quenching. In the latter case, a recycling of a part of the flow exiting HDT1 or HDT2 must be carried out to control the temperature. A strict control of the temperature in HDT1 must be carried out, in order to avoid the plugging of the reactor and the degradation of the catalytic hydrogenation conditions.
The operating pressure in each of the hydrotreatments HDT1 and HDT2 is 5-60 bar, preferably 20-30 bar for HDT1 and 20-140 bar, preferably 30-60 bar for HDT2, typically 30-40 bar for HDT2.
Typical temperature range at the inlet of HDT1 at cycle start (SOR: start of run): 150-200° C. The catalyst for HDT1 usually comprises Pd (0.1-10% weight) and/or Ni (0.1-60% weight) and/or NiMo (0.1-60% weight).
Typical temperature range at the inlet of HDT2 at cycle start (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 HDT2 usually comprises an NiMo (any type of commercial catalyst for refinement or petrochemical use), potentially a CoMo in the very last beds at reactor bottom (any type of commercial catalyst for refinement or petrochemical use).
The upper bed of HDT2 must be operated preferably with an NiMo having a hydrogenating capacity as well as a capacity for trapping silicon. An upper bed of this type can be considered to be an adsorbent as well as a metal trap also having an HDN activity and a hydrogenating capacity. An example of an acceptable upper bed for this function comprises the 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 a reactor HDT2, with a quenching between the two beds or between the two reactors, if the two beds are in two distinct reactors, or no quenching at all. Ideally, the intermediate quenching is carried out via the cold effluent of HDT2 or by an addition of cold hydrogen, that is to say at a temperature generally ranging from 15 to 30° C., in order to control the exotherm of HDT2. A dilution by recycling of the flow of hydrocarbon towards the upper bed of HDT2 is not recommended because of the increased risks of fouling of the bed. The feedstock arriving on the catalyst of HDT2 should be totally vapourised at all times, including in variable state as is the case during the start-ups. The sending of liquid hydrocarbons onto the upper bed of a reactor HDT2 can generate fouling and an increase in the pressure difference between the inlet and the outlet of said reactor HDT2 and lead to premature stoppage.
According to the metals present in the pyrolysis oil to be hydrotreated, a hydrodemetallation catalyst, for example commercial, can be added onto the upper bed of the section HDT2 in order to protect the lower catalytic beds against deactivation.
The hydrotreated pyrolysis oil exiting the section HDT2 can be used as such or fractioned according to the distillation temperature ranges, to feed a steam cracker, an FCC, a hydrocracker, a catalytic reformer or a pool of fuels or combustibles such as GPL, gasoline, jet, diesel, fuel oil.
Alternatively, the treated pyrolysis oil exiting the section HDT2 undergoes an additional step of purification by passing 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 calcinated 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 acidic 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 alkali or alkaline earth cation for example the sieves 3A, 4A, 5A, 13X, for example marketed under the brand Siliporite® 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 out of F, CI, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg and Hg and/or of the water. Ideally, the adsorbent is regenerative, has a specific surface area of at least 200 m2/g and is used in a fixed-bed reactor at less than 100° C. with an SV of 0.1 to 10 h−1.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2109395 | Sep 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2022/051498 | 7/26/2022 | WO |
