Method for treating a composition of natural origin comprising lipids and impurities with an adsorbent

Abstract

The invention relates to a method for treating a composition of natural origin comprising lipids and impurities, the method comprising: (A) a step of bleaching in which the composition of natural origin is brought into contact with an adsorbent, producing an effluent comprising the purified composition of natural origin and the spent adsorbent, (B) a step of hydrotreating the effluent of step (A), carried out in the presence of dihydrogen and at least one catalyst, in order to transform the fatty acid esters and the free fatty acids contained in the purified composition of natural origin into linear or substantially linear paraffins, (C) a step of treating the spent adsorbent of step (A), the spent adsorbent containing from 10% to 30% by weight of a composition of natural origin trapped in the adsorbent, said composition of natural origin comprising lipids and impurities, the step (C) of treating the spent adsorbent of step (A) comprising: (a) bringing the spent adsorbent into contact with supercritical CO2 during which the supercritical CO2 extracts at least some of the lipids that were initially contained in the composition of natural origin and are trapped in the spent adsorbent, while at least some of the impurities remain trapped in the spent absorbent, (b) recovering (i) an effluent resulting from the contacting step containing the supercritical CO2 and the compounds extracted from the spent adsorbent, and (ii) the spent adsorbent resulting from the contacting step containing the impurities, (c) separating the effluent recovered in step (b) into a gas stream containing the CO2 and a liquid phase containing the compounds extracted from the adsorbent, and wherein at least some or all of the liquid phase containing the compounds extracted from the adsorbent resulting from step (C) is (i1) mixed with the composition of natural origin upstream of the bleaching step (A) or during said step (A), and / or upstream of the hydrotreatment step (B) or during said step (B).

Description

[0001] TITLE: PROCESS FOR RECOVERING HYDROCARBON COMPOUNDS TRAPPED IN ADSORBENTS

[0002] Technical field

[0003] The present invention relates to the field of the treatment of hydrocarbon feedstocks of natural origin, in particular with a view to the manufacture of bio-sourced fuels, and more precisely the recovery of compounds trapped in the adsorbents used in the pretreatment of these hydrocarbon feedstocks of natural origin.

[0004] Prior art

[0005] Due to the scarcity of fossil resources and growing environmental concerns, the use of molecules derived from biomass is increasingly sought to replace molecules of fossil origin.

[0006] A well-known process for manufacturing renewable fuel and other hydrocarbon fluids involves subjecting a vegetable or animal fat or oil to hydrotreatment in the presence of dihydrogen and a catalyst, typically leading to hydrodeoxygenation, usually followed by hydroisomerization to obtain the required cold properties.

[0007] This hydrotreatment step is usually preceded by chemical and physical pretreatment steps, such as degumming, neutralization with an alkaline solution (usually NaOH), bleaching, finishing or polishing, steam treatment, cavitation, etc.

[0008] Among these pretreatment steps, bleaching involves contacting the feedstock to be treated with a solid adsorbent and generally ensures the removal of soaps, residual phosphatides, metals, and certain oxidation products, and catalyzes the removal of carotene and even the decomposition of peroxides. Another function is the removal of peroxides and secondary oxidation products. The bleaching process involves contacting the oil with an absorbent, such as clays, synthetic amorphous silica, and activated carbons. After treatment, the adsorbent is separated from the oil and treated as waste, often by methanization or incineration. However, some of the oil remains blocked in the pores of the adsorbent and is thus lost, resulting in a loss of efficiency in the oil treatment and fuel manufacturing process. This blocked oil can represent up to 25% of the adsorbent's weight.

[0009] There is therefore a need to recover a hydrocarbon load of natural origin retained in an adsorbent.

[0010] Summary of the invention

[0011] The invention aims to provide a method for treating a used adsorbent containing from 10 to 30% by mass of a composition of natural origin trapped in the adsorbent, said composition of natural origin comprising lipids and impurities, said method comprising:

[0012] (a) bringing the spent adsorbent into contact with supercritical CO2 during which the supercritical CO2 extracts at least part of the lipids initially contained in the composition of natural origin and trapped in the spent adsorbent, while at least part of the impurities remain trapped in the spent absorbent,

[0013] (b) the recovery of (i) an effluent from the contacting containing the supercritical CO2 and the compounds extracted from the spent adsorbent, and (ii) the spent adsorbent from the contacting containing the impurities,

[0014] (c) separating the effluent recovered in step (b) into a gaseous stream containing the CO2 and a liquid phase containing the compounds extracted from the spent adsorbent.

[0015] Without wishing to be bound by a theory, it is assumed that the supercritical, non-polar CO2 will extract from the used adsorbent the essentially non-polar compounds trapped in the adsorbent, and in particular the non-polar lipids, namely mainly the fatty acid esters, including triglycerides, di-glycerides and / or mono-glycerides, while the polar compounds, and in particular the metals, including alkali metals and / or alkaline earth metals, phospholipids and / or nitrogen compounds and / or chlorinated compounds, which are considered as impurities, remain trapped in the adsorbent. Advantageously, said composition of natural origin may contain one or more oils chosen from a vegetable oil, an animal oil or fat, a used oil or fat, an oil produced by microorganisms, esters resulting from the transesterification of the fatty acid esters contained in one or more of these oils, as well as mixtures thereof.

[0016] Advantageously, the lipids contained in the composition of natural origin may comprise phenolic lipids, fatty acids, phospholipids, fatty acid esters (including triglycerides, diglycerides, monoglycerides), alone or in a mixture.

[0017] Advantageously, the impurities contained in the composition of natural origin may comprise metals, in particular alkali metals and / or alkaline earth metals, and / or nitrogen and / or chlorine, and / or phosphorus, in particular in the form of phosphorus compounds such as phospholipids. In particular, the liquid phase separated from step (c) may have a small amount of impurities (e.g. from 0 to 15% by mass, most often from 0 to 10% by mass, or even from 0 to 5% by mass), or preferably be free of impurities.

[0018] Advantageously, the used adsorbent may come from an adsorbent chosen from a clay, silica, and / or cellulose fibers, preferably a clay, in particular an activated clay.

[0019] The contacting step can be carried out under at least one of the following conditions: a pressure of 15 to 40 MPa and a temperature of 40 to 70 °C, a mass ratio of charge / Supercritical CO2 of 5:1 to 300:1.

[0020] Advantageously, the contacting may be carried out in the presence of an esterifying agent, and / or a polarity modifying agent and / or a diluent, in particular an alcohol, preferably a C1-C4 alcohol, preferably a C1-C2 alcohol. The diluent may also comprise, or consist of, a portion of the liquid phase recovered in step (c). However, preferably, the contacting is carried out without adding an esterifying agent and / or a modifying agent, and without adding a diluent, in particular other than the liquid phase recovered in step (c).

[0021] Advantageously, the contacting can be carried out continuously in a reactor in which the spent adsorbent and the supercritical CO2 circulate countercurrently.

[0022] The method for treating an adsorbent according to the invention can be integrated into a method for treating a composition of natural origin comprising lipids and impurities in order to improve the overall efficiency of this method.

[0023] Thus, the invention also relates to a method for treating a composition of natural origin comprising lipids and impurities, said method comprising:

[0024] (A) a bleaching step in which said composition of natural origin is brought into contact with an adsorbent producing an effluent comprising the purified composition of natural origin and the spent adsorbent,

[0025] (B) a hydrotreatment step of the effluent from step (A),

[0026] (C) a step of treating the used adsorbent from step (A) according to the invention.

[0027] Advantageously, the liquid phase containing the compounds extracted from the adsorbent resulting from step (C) can be, at least in part or in whole, (i1) mixed with the composition of natural origin upstream of the bleaching step (A) or during this step (A), and / or upstream of the hydrotreatment step (B) or during this step (B), and / or (i2) added to the used adsorbent entering the treatment step (C).

[0028] In particular, when step (C) of treatment of the adsorbent is carried out in the presence of an esterifying agent, the liquid phase resulting from step (C) containing the compounds extracted from the adsorbent can then advantageously be sent upstream of step (B) of hydrotreatment after separation of the glycerol.

[0029] Definitions

[0030] The terms "comprising" and "comprises" as used herein are synonymous with "including", "includes" or "contains", "containing", and are inclusive or unbounded and do not exclude additional features, elements or method steps not specified. The expressions % by weight and % by mass (also noted "%m") have an equivalent meaning and refer to the proportion of the mass of a product relative to 100 g of a composition comprising it.

[0031] Atmospheric pressure is the actual measured pressure. It therefore varies around normal atmospheric pressure (1013.25 mbar).

[0032] Detailed description of the invention

[0033] The present invention relates to a method for treating an adsorbent containing from 10 to 30% by mass of a composition of natural origin, in particular incorporated into a method for treating this composition of natural origin.

[0034] Composition of natural origin

[0035] The composition of natural origin trapped in the adsorbent used in the present invention is a composition comprising lipids and impurities, and in particular heteroatoms, lipids chosen from phenolic lipids, fatty acids, triglycerides, diglycerides, monoglycerides, phospholipids, fatty acid esters and / or a mixture of two or more of these compounds.

[0036] This composition may include, or consist of, a naturally derived oil or a mixture of natural oils. A naturally derived oil is defined as an oil that does not contain mineral oil of fossil origin.

[0037] The composition according to the invention may contain one or more oils of natural origin chosen from a vegetable oil, an animal oil or fat, a used oil, an oil produced by microorganisms, animal fats and used cooking oils which are animal by-products, esters resulting from the trans-esterification of the fatty acid esters contained in one or more of these oils, as well as their mixtures.

[0038] Compositions resulting from the transesterification of fatty acid esters contained in these oils, such as compositions comprising fatty acid methyl esters or fatty acid ethyl esters, and comprising impurities originating from the oils, may also be part of the treated naturally derived compositions considered in the present invention. Typically, a naturally derived oil may contain 50%m or more, 60%m or more, preferably 70%m or more, of phenolic lipids, fatty acids and / or fatty acid esters (mono-, di-, triglycerides, fatty acid ethyl esters, fatty acid methyl esters).

[0039] An oil of natural origin may contain 50%m or more of fatty acid esters (mono-, di-, triglycerides, fatty acid ethyl esters, fatty acid methyl esters) and / or fatty acids, preferably 60%m or more, preferably 70%m or more.

[0040] In one embodiment, a naturally occurring oil or a mixture of naturally occurring oils may contain fatty acid esters and free fatty acids containing one to three C8-C24 acyl groups, saturated or unsaturated. When multiple acyl groups are present, they may be the same or different.

[0041] An oil of natural origin may contain 50%m or more, preferably 60%m or more, preferably 70%m or more, of phenolic lipids. These phenolic lipids include in particular the compounds represented by the formula (1):

[0042] [Chem 1]

[0043] Or :

[0044] R is a straight-chain C10-C30, optionally C12-C20, for example C15, saturated or unsaturated alkyl group, substituted or not by heteroatoms chosen from O, N or S, R 1 is hydrogen or a hydroxyl group, R 2 is hydrogen, a carboxylic group or an ester, R3 is hydrogen.

[0045] The oil of natural origin may in particular comprise one or more of the following phenolic lipids: - alkylated phenols whose alkyl group is a linear chain in C10-C30, optionally in C12-C20, for example in C15, saturated or not, substituted or not by heteroatoms chosen from O, N or S,

[0046] - alkylresorcinols whose alkyl group has a linear chain of C10-C30, optionally C12-C20, for example C15, saturated or not, substituted or not by heteroatoms chosen from O, N or S,

[0047] - anacardic acids, the alkyl group of which has a linear chain of C10-C30, optionally C12-C20, for example C15, saturated or not, substituted or not by heteroatoms chosen from O, N or S.

[0048] The vegetable oil can be chosen from pine oil, rapeseed oil, sunflower oil, castor oil, peanut oil, linseed oil, babasu oil, hemp oil, linola oil, jatropha oil, peanut oil, rice bran oil, mustard oil, carinata oil, coconut oil, copra oil, olive oil, palm oil, cottonseed oil, corn oil, palm kernel oil, soybean oil, pumpkin oil, grapeseed oil, argan oil, jojoba oil, sesame oil, walnut oil, hazelnut oil, tung oil, rice oil, safflower oil, algae oil, used oils, nut shell oil (including cashew nut shell oil), and any combination thereof.

[0049] Used oil includes used cooking oil or used edible oil and oils recovered from waste water, such as trap and drain grease / oil, gutter oil, sewer oil, e.g. from water treatment plants, and used grease from the food industry.

[0050] Animal fat can be chosen from tallow, lard, fat (yellow and brown fat), fish oil / fat, milk fat, animal fats which are animal by-products.

[0051] In particular, animal fats and used cooking oils which are animal by-products have the status of animal by-products within the meaning of Regulation (EC) No 1069 / 2009 of the European Parliament and of the Council of 21 October 2009 and Commission Regulation (EU) No 142 / 2011 (implementing regulation of Regulation EC No 1069 / 2009).

[0052] Animal fats with animal by-product status are fatty residues of animal origin, other than used cooking oils, for example from food industries or rendering plants.

[0053] Used cooking oils with the status of animal by-products are used cooking oils (used cooking oils or UCO), namely residues of fats of vegetable or animal origin used for human consumption, in the food industry, in collective or commercial catering.

[0054] Naturally occurring oil can also be oil produced by microorganisms, whether natural or genetically modified, such as bacteria, yeasts, including oleaginous yeasts, algae, prokaryotes or eukaryotes. In particular, these oils can be recovered by well-known mechanical or chemical extraction methods.

[0055] The above-mentioned oils of natural origin, most of which are rich in triglycerides or phenolic lipids, also contain varying amounts of components such as free fatty acids, mono- and diglycerides, and / or numerous other organic and inorganic components, including phosphatides, sterols, tocopherols, tocotrienols, hydrocarbons, pigments (gossypol, chlorophyll), vitamins (carotenoids), sterol glucosides, glycolipids, protein fragments, traces of pesticides and traces of metals, as well as resinous and mucilaginous materials. Among the latter components, some compounds, especially those containing heteroatoms, are pollutants that are preferable to be at least partially removed before further processing.

[0056] The composition of natural origin according to the invention thus typically comprises heteroatoms, including in particular phosphorus and / or nitrogen. These heteroatoms are generally in the form of organic compounds, in particular in the form of lipids. The phosphorus content of the composition of natural origin may be 20 ppm or more or 50 ppm or more, for example from 50 ppm to 1500 ppm, or from 200 ppm to 1200 ppm, measured for example by X-ray fluorescence or ICP using the UOP 389 method.

[0057] The nitrogen content of the naturally occurring composition may be 50 ppm or more, for example 50 ppm to 1200 ppm or 200 ppm to 2000 ppm, measured for example by X-ray fluorescence.

[0058] The naturally occurring composition may further comprise one or more other heteroatoms such as alkali metals, including potassium, alkaline earth metals, and / or chlorine. The content of these heteroatoms may vary depending on the constituents of the composition. It may be determined by elemental analysis such as X-ray fluorescence or ICP.

[0059] In the composition of natural origin considered in the invention, phosphorus may in particular be present in the form of phosphatides, the most common of which are phosphatic acid, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol and phosphate salts. As these compounds are often charged due to their low (phosphate group) or high (amino group) pKa, they may also contain alkali or alkaline-earth elements or absorb metal cations such as copper or iron.

[0060] Nitrogen is present in phosphatidylcholine and phosphatidylethanolamine. It can also be present in naturally occurring compounds in the form of chlorophyll, protein residues, fatty amines, etc.

[0061] Metals, in particular alkali metals and / or alkaline earth metals, and / or nitrogen, and / or chlorine, and / or phosphorus, in particular more precisely the compound(s) containing these heterotaomes, present in the composition of natural origin considered in the invention are considered as impurities.

[0062] Detailed description of the process for treating a used adsorbent

[0063] Due to their pollutant content, the previously described natural oils are typically subjected to one or more chemical and physical pretreatments well known to those skilled in the art in order to reduce their pollutant content before being sent to a subsequent hydrotreatment step. The elimination of these pollutants makes it possible to prevent corrosion of the catalysts used downstream as well as corrosion of the equipment.

[0064] Among these pretreatments, bleaching consumes significant quantities of adsorbent while the recovered spent adsorbent contains significant quantities of oil trapped in its pores, this oil representing 10 to 30% of its mass, generally around 25% by mass.

[0065] The treatment process according to the invention makes it possible to recover this oil trapped in the spent adsorbent by supercritical CO2 extraction, without the impurities trapped in the spent adsorbent. By "spent adsorbent" is meant an adsorbent which has been used in a bleaching process for a composition of natural origin. The adsorbent may be as described with reference to step (A) of the process for treating a composition of natural origin of the invention.

[0066] To this end, a spent adsorbent containing 10 to 30% by mass of a natural oil composition as previously described is first brought into contact (a) with supercritical CO2. The latter extracts from the spent adsorbent at least a portion of the lipids initially contained in the natural oil composition and trapped in the spent adsorbent, while the impurities remain, at least in part, trapped in the absorbent.

[0067] Then (b) the recovery of (i) an effluent from the contact containing the supercritical CO2 and the compounds extracted from the spent adsorbent, and (ii) the spent adsorbent from the contact containing the impurities is carried out.

[0068] Finally, (c) the separation of the effluent recovered in step (b) into a gaseous flow containing the CO2 and a liquid phase containing the compounds extracted from the used adsorbent is carried out.

[0069] The compounds extracted from the spent adsorbent include, or consist of, at least a portion of the lipids initially contained in the naturally occurring composition, and possibly other compounds soluble in supercritical CO2.

[0070] The lipids extracted during contacting step (a) typically comprise, or consist of, fatty acid esters, and in particular triglycerides, diglycerides, and / or monoglycerides, and / or free fatty acids. Contacting step a) may be carried out in the presence of a polarity modifying agent. By "polarity modifying agent" is meant a polar compound soluble in supercritical carbon dioxide and which increases the polarity of said supercritical carbon dioxide.

[0071] Polarity modifying agents are well known to those skilled in the art and are typically chosen from short-chain alcohols.

[0072] Short-chain alcohols are defined as linear or branched C1-C4 alkanes substituted by a hydroxyl group, in particular methanol or ethanol.

[0073] The use of a polarity modifying agent can improve the extraction of polar compounds of interest, particularly fatty acid esters and / or fatty acids.

[0074] In particular, the mass fraction of the polarity modifying agent in the supercritical CO2 phase can be 0 to 20%.

[0075] The contacting step (a) can also be carried out in the presence of an esterifying agent.

[0076] Esterifying agent means a reactive compound or composition allowing the esterification of lipids bearing a carboxylic acid group.

[0077] The esterification agents are well known to those skilled in the art and are in particular chosen from short-chain alcohols, in particular C1-C4; short-chain alcohols and a catalyst chosen from acids and bases.

[0078] The esterifying agent may in particular be methanol or ethanol, and optionally a base such as hydroxide or potassium hydroxide, or an acid, such as sulfuric acid, p-toluenesulfonic acid, 4-methylbenzenesulfonic acid, benzenesulfonic acid, methylsulfonic acid, nitric acid, acetic acid, phosphoric acid, preferably sulfuric acid.

[0079] In the presence of an esterifying agent, which is mixed with supercritical CO2, extraction and transesterification of lipids can be carried out, leading to the extraction of fatty acid methyl esters (FAMEs) or fatty acid ethyl esters (FAEs), when said esterifying agent is for example methanol or ethanol, in the presence or absence of a catalyst. The transformation of lipids into the corresponding esters can improve the separation because esters are more soluble in supercritical CO2 than their corresponding lipids (glycerides or free fatty acids).

[0080] When short-chain alcohols are mixed with supercritical CO2, they can thus act as both a polarity-modifying agent and an esterifying agent, depending on their alcohol concentration.

[0081] The spent adsorbent may optionally be fluidized by adding a diluent, for example an alcohol, in particular a C1-C4 alcohol, preferably methanol or ethanol, and / or by adding a portion of the liquid phase containing the compounds extracted from the adsorbent separated in step (c). The diluent may represent 5 to 20% by mass of the spent adsorbent entering the contacting step (a). The diluent may in particular be an esterification agent as previously described.

[0082] By supercritical CO2 phase is meant supercritical CO2 as defined in step (a), and including, where appropriate, the polar modifying agent and / or the esterifying agent and / or the diluent.

[0083] Contacting step (a) can be carried out under a pressure of 15 to 40 MPa and at a temperature of 40 to 70°C.

[0084] The pressure is typically less than 40 MPa to ensure some difference between the densities of the contacted phases, while allowing the solubilization of lipids in the supercritical phase.

[0085] The pressure and temperature to be applied during contact depend on the solubility of the compounds to be extracted from the adsorbent used by supercritical CO2, and can be adapted, particularly in the above-mentioned ranges, by tests.

[0086] The mass ratio [supercritical CO2 flow rate] / [spent adsorbent flow rate] may preferably be from 5:1 to 300:1, for example from 2:1 to 250:1.

[0087] Contacting can be carried out in any suitable contacting device, for example a reactor, a fractionating column or a decanter-mixer.

[0088] The treatment of the spent adsorbent may be continuous or not (batch treatment). When it is continuous, the flow rates of supercritical CO2 and spent adsorbent may be determined by a person skilled in the art depending on the dimensions of the contacting device. When it is not continuous, only the flow rate of supercritical CO2 must be determined.

[0089] In one embodiment, in particular for continuous treatment of the spent adsorbent, the spent adsorbent and the supercritical CO2 may advantageously be introduced countercurrently, for example in a contacting device allowing countercurrent extraction and recovery of an upper (lighter) phase and a lower (heavier) phase, such as a fractionating column or a decanter-mixer. More precisely, the spent adsorbent is then introduced at the top of the contacting device and the supercritical CO2 is introduced at the bottom of the contacting device. The flows of the two phases are induced by the difference in gravity; the spent adsorbent constitutes the descending phase and the supercritical phase constitutes the ascending phase.

[0090] When contacting is carried out in a fractionation column, the contact between the spent adsorbent and the supercritical phase can be improved by using packing in the fractionation column. Packed fractionation columns increase the contact surface area between the contacted phases, thus enabling good mass transfer.

[0091] In another embodiment, in particular for batch treatment of the used adsorbent, the latter may be arranged in one or more fixed beds crossed by the supercritical CO2 in the contacting device. This may be implemented in a reactor, this reactor possibly being equipped with packing upstream of the adsorbent bed(s) with respect to the circulation of supercritical CO2. The supercritical phase may be a descending or ascending phase.

[0092] Without wishing to be bound by a theory, thanks to the high contact surface between the two phases and the specific mass transfer properties of supercritical fluids, CO2 can diffuse easily into the mass of the spent adsorbent, and more particularly inside its pores, which makes it possible to extract the compounds most soluble in supercritical CO2. The recovery (b) of the effluent from the contacting containing the supercritical CO2 and the compounds extracted from the spent adsorbent, on the one hand, and the spent adsorbent from the contacting containing the impurities, on the other hand, is now described.

[0093] When the spent adsorbent is processed continuously, the phases exiting the top and bottom of the used contacting device flow naturally due to gravity differential. The upper phase, which is the extract (or lighter phase), contains mainly supercritical CO2 and lipids (and / or other extracted compounds). The lower phase is generally called the raffinate (or heavier phase). The lower phase is composed mainly of spent adsorbent, impurities, and small amounts of CO2. Both phases (upper phase and lower phase) are collected continuously by simple depressurization. Upon exiting the contacting device, the upper and lower phases return to a lower pressure (to the contacting pressure) or directly to ambient pressure.

[0094] When the treatment of the spent adsorbent is not continuous, a phase (an effluent) containing mainly supercritical CO2 and lipids (and / or other extracted compounds) is recovered at the lower or upper end of the contacting device. At the outlet of the contacting device, this phase returns to a lower pressure (than the contacting pressure) or directly to ambient pressure. When all the spent adsorbent has been treated, the device is stopped, depressurized and the adsorbent replaced by a new batch of spent adsorbent to be treated.

[0095] Once recovered, the effluent from the contact containing the supercritical CO2 and the compounds extracted from the spent adsorbent is separated (c) into a gaseous stream containing the CO2 and a liquid phase containing the compounds extracted from the adsorbent, as described below.

[0096] Regardless of the embodiment, when brought to ambient pressure, the supercritical CO2 returns to the gaseous state and the extracted compounds it contains are spontaneously separated from the CO2. Thus, the phase containing the supercritical CO2 and the extracted compounds is depressurized and the CO2 is separated from the remaining liquid phase, typically collected in a separator. The separation of the supercritical CO2 is spontaneous and easily achieved by simple depressurization, for example in a separator arranged at the outlet of the contacting device. The remaining liquid phase is mainly composed of lipids (fatty acid esters, and in particular tri-, di- and monoglycerides, as well as free fatty acids), and possibly other apolar compounds extracted by the supercritical CO2. It may contain impurities in small quantities (from 0 to 15% by mass, most often from 0 to 10% by mass, or even from 0 to 5% by mass), or be free of impurities.CO2 can advantageously be recycled in the contacting step with a recycling rate of 98% for example.

[0097] The liquid phase can then be returned to a process for treating a composition of natural origin in order to increase its yield.

[0098] The recovered spent adsorbent is depressurized and the CO2 (contained in relatively small quantities) is separated from the spent adsorbent. The latter contains the various compounds insoluble in supercritical CO2, and in particular impurities such as metals, especially alkali and / or alkaline earth metals, phosphorus, chlorine and / or nitrogen. The recovered spent adsorbent, considered as waste, can be recycled according to the site's possibilities or destroyed.

[0099] The contacting device can include several sections in which different temperatures can be applied. An induced internal reflux can improve the separation. In this case, the feed may not be introduced at the top of the device, but in the middle or between the middle and the top. The pressure will preferably be 15 to 40 MPa. Indeed, for such pressure conditions, retrograde behavior is observed. This means that the solubility of the solute in supercritical CO2 decreases as the temperature increases. Thus, if the upper section is at a higher temperature than the other lower sections, the solutes solubilized in the supercritical phase in the lower sections will condense (since they will be less soluble at higher pressure) thus creating an internal reflux.

[0100] The use of a temperature gradient along several sections of a contacting device, in particular a fractionation column, is well known to those skilled in the art and is notably described by Michel Perrut in "Extraction par fluide supercritique", DOI: 10.51257 / a-v1-j2770, Techniques de l'ingénieur, 1999).

[0101] Process for treating a composition of natural origin

[0102] The previously described composition of natural origin, optionally after having undergone one or more pretreatments such as a degumming pretreatment and a neutralization pretreatment, is subjected to a bleaching step (A) before being sent to a hydrotreatment step (B), optionally after an intermediate treatment, such as a finishing or polishing treatment, a steam treatment, cavitation, etc.

[0103] During bleaching step (A), the composition of natural origin is brought into contact with an adsorbent producing an effluent comprising the purified composition of natural origin and the spent adsorbent.

[0104] The adsorbent used may be any adsorbent capable of adsorbing a specific category of compounds, including metals, phosphorus, chlorine and / or nitrogen, commonly used to purify naturally occurring compositions. The adsorbent material may be a mineral material or a surface-activated or surface-treated material, for example, a surface-activated or surface-treated mineral material.

[0105] The adsorbent may comprise, or consist of, a clay, silica, and / or cellulose fibers, preferably a clay.

[0106] For example, diatomaceous earth, diatomite, perlite, bentonite, palygorskite, kaolin, kaolinite, silica and / or sepiolite, or any combination of these materials, may be used as the mineral material, optionally activated or surface-treated, for example, bentonite, acid-activated or acid-treated.

[0107] In the context of the present invention, "activated" or "surface-treated" means any process capable of modifying the characteristics of the adsorbent material, such as a mineral-based material, in terms of its ability to increase, for example, the adsorption of a class of agent(s). Surface activation may significantly increase or enhance the surface area of ​​the adsorbent material, for example by introducing pores, which provides more surface area for adsorption. In addition to, or as an alternative to, increasing the surface area, the surface of the adsorbent may be chemically activated to exhibit better adsorbent properties (for example, by surface acidity). Surface activation may be carried out in one or more steps, for example, using one or more surface-activating agents.For example, a surface activating agent such as an acid increases both the surface area of ​​the adsorbent and the chemical adsorption properties of the adsorbent material.

[0108] A typical way to activate an adsorbent or mineral to increase its adsorption properties is to boil it for several hours in an aqueous solution of mineral acid (e.g., sulfuric or nitric acid), wash the activated adsorbent or mineral with water to remove excess acid, dry the activated adsorbent or mineral, and optionally grind it to a suitable particle size.

[0109] The adsorbent material, preferably surface activated, may have one or more of the following characteristics:

[0110] - a pore size (pore width) for example less than about 1 pm, less than about 0.1 pm, less than about 0.05 pm, less than about 0.002 pm, or for example from about 0.002 to about 0.05 pm,

[0111] - a permeability of from about 0.1 to about 20 Darcy, from about 0.2 to about 2.5 Darcy, from about 0.2 to about 1 Darcy or from about 0.5 to about 1.0 Darcy, or preferably between 0.2 and 1 Darcy,

[0112] - particle sizes from about 1 pm to about 1000 pm, for example from about 1 pm to about 500 pm, from about 1 pm to about 100 pm, from about 10 pm to about 500 pm, from about 10 pm to about 100 pm, for example from about 50 pm to about 250 pm, preferably from about 1 pm to about 1000 pm,

[0113] - a specific surface area of ​​approximately 100 m 2 / g or more, such as about 250 m 2 / g or more, about 300 - 400 m 2 / g or more, or about 500 m 2 / g or more, such as about 1000 m 2 / g or more.

[0114] The adsorbent material used in step (A) is preferably capable of adsorbing compounds containing phosphorus and / or metals, etc. Thus, the purified naturally occurring composition emerging from step (A) has reduced amounts of compounds containing metals and / or phosphorus, or is essentially free of compounds containing metals and / or phosphorus.

[0115] The contacting of step (A) may comprise mixing the naturally occurring composition with the adsorbent by any known means, for example by mechanical mixing, or otherwise. Alternatively, the contacting may be carried out by placing the adsorbent on one or more supports or surfaces, such as filters.

[0116] Contacting is typically carried out for a duration of 1 minute to 360 minutes, for example 5 to 60 minutes.

[0117] The adsorbent brought into contact with the composition of natural origin may be present in an amount of 0.1 to 3% by mass relative to the mass of the composition of natural origin to be purified, for example 0.5 to 1.5% by mass.

[0118] During the contacting step, the composition of natural origin may be at a temperature of 15°C to 100°C, advantageously 15 to 80°C.

[0119] After contact, the purified natural composition is separated from the adsorbent, for example by filtration using one or more filters, or by centrifugation, sedimentation, decantation, or a combination of these techniques.

[0120] It is then subjected to hydrotreatment step (B).

[0121] This hydrotreatment step is typically carried out in the presence of dihydrogen and at least one catalyst to transform the fatty acid esters and free fatty acids, contained in the purified naturally occurring composition, into linear or substantially linear paraffins.

[0122] Hydrotreatment can be carried out between 100 and 550 °C in the presence of dihydrogen at pressures ranging from 0.01 to 10 MPa. The ratio of dihydrogen to feedstock can be 100 to 2000 Nl / I.

[0123] The hydrotreatment can be carried out in the presence of at least one catalyst chosen from (i) oxides, phosphides or sulfides of Ni, Mo, W, Co or mixtures of NiW, NiMo, CoMo, NiCoW, NiCoMo, NiMoW and CoMoW, (ii) metals or mixtures of metal alloys from group 10 and group 11 of the periodic table, (iii) basic oxides such as alkali metal oxides, alkaline earth oxides, lanthanide oxides, zinc oxide, spinels, perovskites, calcium silicates.

[0124] The hydrotreatment step (B) can be carried out in one or more reactors. Any type of reactor normally used for this type of reaction can be used, for example a fixed-bed reactor, a stirred-tank reactor, an ebullated-bed reactor, a slurry-type reactor, etc., preferably a fixed-bed reactor.

[0125] This hydrotreatment step may comprise one or more steps chosen from hydrodeoxygenation, decarboxylation and decarbonylation. A person skilled in the art will be able to choose the operating conditions in order to favor one or other of these reactions depending on the desired result.

[0126] The hydrodeoxygenation may for example be carried out at a temperature of 200 to 500 °C, preferably 220 to 400 °C, under a pressure of 1 MPa to 10 MPa (10 to 100 bar), for example 6 MPa, and with a dihydrogen / oil ratio of 100 to 2000, but preferably 350 to 1500, for example 800 NI H2 / I oil.

[0127] The decarboxylation and / or decarbonylation step may for example be carried out between 100 and 550 °C in the presence of dihydrogen at pressures ranging from 0.01 to 10 MPa. The ratio between dihydrogen and feedstock may be from 100 to 2000 Nl / I.

[0128] The hydrotreated effluent produced by the hydrotreatment step may optionally be subjected to subsequent hydroisomerization and / or hydrocracking steps for the production of a fuel.

[0129] According to the invention, the adsorbent used during bleaching step (A), now spent, is subjected (C) to the method for treating a spent adsorbent according to the invention in order to recover the composition of natural origin which has remained trapped. The implementation of the method for treating the spent adsorbent makes it possible to recover a liquid phase containing the compounds extracted from the spent adsorbent, namely essentially lipids. This liquid phase can be mixed with the composition of natural origin upstream of bleaching step (A) or during this step (A), and / or upstream of hydrotreatment step (B) or during this step (B), and / or be added to the spent adsorbent entering treatment step (C). Preferably, the liquid phase is added in part or in whole, preferably in whole, to the composition of natural origin upstream of step (A) or (B) or during these steps, in order to increase the total yield of the process.We can choose to return this liquid phase to step (A) or (B) depending on its possible impurity content.

[0130] Preferably, only a part of this liquid phase, advantageously a minor part (less than 50% by mass, preferably less than 25% by mass), is added to the used adsorbent entering the treatment step (C), the remainder being sent upstream of step (A) or (B) or during these steps.

[0131] In a preferred embodiment, the liquid phase is only added to the composition of natural origin upstream of step (A) or (B) or during these steps.

[0132] Description of figures

[0133] Non-limiting examples of implementation of the invention are now described with reference to the figures.

[0134] [Fig. 1] Figure 1 is a schematic representation of one embodiment of the method for treating a spent adsorbent.

[0135] [Fig. 2] Figure 2 is a schematic representation of an embodiment of the method for treating a composition of natural origin implementing the method for treating a used adsorbent.

[0136] In Figure 1, the used adsorbent, containing from 10 to 30% by mass of a composition of natural origin, enters via a pipe 1 into a contacting device 10 for the implementation of step (a) of the method according to the invention. In the non-limiting example shown, this contacting device 10 is an extraction column in which the fluids circulate counter-currently. The pipe 1 thus opens into the device 10 in the upper part. The flow rate and pressure of the used adsorbent can be controlled by means of a pump 2 and a valve 3. The used adsorbent leaves the device 10 in the lower part via a pipe 4, generally equipped with a valve 5. At the outlet of the device 10, the used adsorbent has a reduced lipid content.

[0137] The CO2 is introduced into a pipe 6 via a valve 7, then is pressurized by means of a high-pressure pump 8, for example a piston pump. The latter thus delivers supercritical CO2 at the desired flow rate. This enters the device 10 in the lower part, is then brought into contact with the spent adsorbent so that it extracts the compounds soluble in the supercritical CO2, and leaves it in the upper part via a pipe 9. It then passes through a depressurization device 11, for example a pressure regulator, before entering a separator 12, for example of the cyclonic type. The latter makes it possible to recover on the one hand a liquid phase via a pipe 13 equipped with a valve 14, and on the other hand the CO2 via a pipe 15 equipped with a valve 16. The separated CO2 can be returned, in part or in whole, via a valve 17 in the pipe 6 to return to the contacting device 10.

[0138] In Figure 2, a composition of natural origin is introduced via a pipe 100 into a contacting device 110 for implementing step (A) of the method according to the invention. The adsorbent used for this bleaching step is introduced into the device 110 via a pipe 101. At the end of this contacting, the purified composition of natural origin is recovered via a pipe 102 and the used adsorbent via a pipe 103. This separation can be carried out as previously described, within the device 110 or by means of a suitable separation system not shown. The purified composition of natural origin then enters a hydrotreatment section 120 to undergo hydrotreatment according to step (B) of the invention and produce a hydrotreated effluent discharged via the pipe 104.

[0139] The spent adsorbent circulating in the pipe 103 is sent to the treatment method described with reference to FIG. 1 via the pipe 1 in order to recover the composition of natural origin which has remained trapped. As shown, the liquid phase thus recovered via the pipe 13 can be returned upstream of the bleaching step (A), and / or upstream of the hydrotreatment step (B), or even be mixed, at least in part, with the spent adsorbent before it enters the contacting device 10. Different valves and pumps (not shown) can further be provided to regulate the flow rates and distribute the fluids between the devices 110, 120 and 10.

Claims

CLAIMS 1. Method for treating a composition of natural origin comprising lipids and impurities, said method comprising: (A) a bleaching step in which said composition of natural origin is brought into contact with an adsorbent producing an effluent comprising the purified composition of natural origin and the spent adsorbent, (B) a step of hydrotreatment of the effluent from step (A) carried out in the presence of dihydrogen and at least one catalyst to transform the fatty acid esters and the free fatty acids, contained in the purified composition of natural origin, into linear or substantially linear paraffins, (C) a step of treating the spent adsorbent from step (A), the spent adsorbent containing from 10 to 30% by mass of a composition of natural origin trapped in the adsorbent, said composition of natural origin comprising lipids and impurities, said step (C) of treating the spent adsorbent from step (A) comprising: (a) bringing the spent adsorbent into contact with supercritical CO2 during which the supercritical CO2 extracts at least part of the lipids initially contained in the composition of natural origin and trapped in the spent adsorbent, while at least part of the impurities remain trapped in the spent absorbent, (b) the recovery of (i) an effluent from the contacting containing the supercritical CO2 and the compounds extracted from the spent adsorbent, and (ii) the spent adsorbent from the contacting containing the impurities, said compounds extracted from the spent adsorbent comprising at least a portion of the lipids initially contained in the composition of natural origin, said extracted lipids comprising fatty acid esters and / or free fatty acids, (c) separating the effluent recovered in step (b) into a gaseous stream containing the CO2 and a liquid phase containing the compounds extracted from the adsorbent, and in which the liquid phase containing the compounds extracted from the adsorbent from step (C) is, at least in part or in whole, (il) mixed with the composition of natural origin upstream of the bleaching step (A) or during this step (A), and / or upstream of the hydrotreatment step (B) or during this step (B).

2. Treatment method according to claim 1, characterized in that said composition of natural origin contains one or more oils chosen from a vegetable oil, an animal oil or fat, a used oil or fat, an oil produced by microorganisms, esters resulting from the transesterification of the fatty acid esters contained in one or more of these oils, as well as their mixtures.

3. Treatment method according to claim 1 or 2, characterized in that the lipids contained in the composition of natural origin comprise phenolic lipids, fatty acids, phospholipids, fatty acid esters, alone or in a mixture.

4. Treatment method according to any one of claims 1 to 3, characterized in that the impurities contained in the composition of natural origin comprise metals, in particular alkali metals and / or alkaline earth metals, and / or nitrogen, and / or chlorine, and / or phosphorus.

5. Treatment method according to any one of claims 1 to 4, characterized in that the used adsorbent comes from an adsorbent chosen from a clay, silica, and / or cellulose fibers, preferably a clay.

6. Treatment method according to any one of claims 1 to 5, characterized in that the contacting of step (a) is carried out under at least one of the following conditions: a pressure of 15 to 40 MPa and a temperature of 40 to 70 °C, a mass ratio of charge / Supercritical CO2 of 5:1 to 300:

1.

7. Treatment method according to any one of claims 1 to 6, characterized in that the contacting is carried out in the presence of an esterification agent and / or a polarity modification agent and / or a diluent.

8. Treatment method according to any one of claims 1 to 7, characterized in that the contacting of step (a) is carried out continuously in a reactor in which the adsorbent and the supercritical CO2 circulate in countercurrent.

9. Treatment method according to any one of claims 1 to 8, characterized in that the liquid phase containing the compounds extracted from the adsorbent from step (C) is, at least in part (i2) added to the used adsorbent entering the treatment step (C).

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