Continuous countercurrent leaching process for the recycling of catalyst metals

Abstract

The present invention relates to a continuous process for countercurrent leaching of a spent catalyst comprising at least one metal from group VIB, and / or at least one metal from group VIII, optionally phosphorus and / or sulfur, and a support based on oxide(s), characterized in that said process comprises N leaching steps, N being greater than or equal to 2, by countercurrently contacting the spent catalyst with a leaching solution comprising at least one organic compound, the leaching solution being fed continuously and passing through each of the leaching steps in the opposite direction to the circulation of the spent catalyst, each leaching step being followed by a solid / liquid separation step to obtain a solution of extracted metal / metals and a catalyst depleted in metal / metals.

Description

Title of the invention: Continuous countercurrent leaching process for the recycling of catalyst metals Technical field

[0001] The present invention relates to the recycling of catalyst metals originating in particular from hydrocarbon hydrotreatment or hydroconversion units. More particularly, the present invention relates to a continuous countercurrent leaching process for the recycling of catalyst metals, making it possible to ensure a high metal extraction rate and reduced leaching solution consumption. Prior art

[0002] Most of the technological innovations needed for the energy transition (electric vehicles, wind power, fuel cells, batteries, etc.) require the massive use of metals. In order to meet this demand while ensuring sustainable development, metal recycling is becoming a major challenge for the coming century.

[0003] In particular, spent catalysts from hydrocarbon hydrotreatment or hydroconversion units contain metals of interest, namely at least one metal from group VIB and at least one metal from group VIII. Once spent, the metals contained in these catalysts are not currently recycled for the manufacture of new catalysts: they are essentially reused for the manufacture of special alloys, requiring complex purification operations, in particular to rid the recovered metals of compounds deemed to be contaminants, such as arsenic, or problematic in view of the intended applications, such as phosphorus, the presence of which disrupts, for example, the properties of chrome steel alloys.

[0004] However, processes have been developed to recover metals from catalysts, in order to recycle them for the manufacture of new catalysts.

[0005] For example, patent application US 2007 / 0167321 proposes to recover molybdenum from used catalysts to make new catalysts. To do this, according to this process, the used catalyst is dispersed in a basic solution, a contaminant / compound contained in the used catalyst that is to be eliminated (arsenic, phosphorus) is removed from the solution by precipitating it, and then the solution is filtered. The molybdenum is then precipitated by changing the pH of the solution to an acidic pH. The molybdenum precipitate is filtered so that it can be reused by dispersion in an impregnation solution also containing precursors of other metals, such as precursors of cesium, antimony or vanadium, and other components necessary to constitute the new catalyst by impregnation of a support.

[0006] Patent application FR3117381 proposes the production of a recycled catalyst for hydrotreatment or hydroconversion of hydrocarbons. Cobalt and molybdenum are extracted by an aqueous solution containing at least one organic acid. The solution obtained is then used directly for impregnation on an aluminum support, to produce a recycled catalyst. The extracted metals remain in the liquid phase throughout this process.

[0007] Most processes for recovering metals operate in batch mode by providing one or more contacts between the leaching solution and the solid, without moving the solid. On an industrial scale and in the case of high tonnages, these processes can be improved.

[0008] Indeed, it is often preferable to opt for a continuous process beyond a certain tonnage, with multi-stage implementation ensuring greater extraction. Contact with the leaching solution can be done in co-current or counter-current of the solid to be treated, the latter option being preferred because it allows a significant reduction in the consumption of leaching solution.

[0009] Continuous countercurrent leaching processes are known in other fields. An example is application WO2021 / 133435A1 which describes a continuous countercurrent extraction process for purifying solid biomass. The latter passes through a series of stirred tanks while an acidified aqueous solution circulates in the opposite direction to maximize the performance of the process. In this type of process, the solid is dispersed in the liquid in the form of a suspension (or slurry according to English terminology), requiring separation steps between each stage by means of an injection of air to fluidize the solid before separating it on a grid outside the tank.

[0010] Another way of proceeding is to move the solid rather than a slurry, making it possible to limit the number of equipment to be implemented. Moving baskets, a conveyor belt or a moving grid can be used for this purpose. For example, application WO2020 / 078811A1 describes a method for producing a plant protein concentrate from a plant material, by extracting soluble carbohydrates with an aqueous alcohol solvent. The solvent extraction is carried out in a conveyor belt extractor equipped with a means for cleaning the belt on its return path.

[0011] The present invention aims to improve the processes for recovering metals from catalysts by providing a continuous countercurrent leaching process for recycling catalyst metals. Summary of the invention

[0012] The invention relates to a continuous process for countercurrent leaching of a spent catalyst comprising at least one metal from group VIB, and / or at least one metal from group VIII, optionally phosphorus and / or sulfur, and a support based on oxide(s), characterized in that said process comprises N leaching steps, N being greater than or equal to 2, by countercurrent contacting of the spent catalyst with a leaching solution comprising at least one organic compound, the leaching solution being fed continuously and passing through each of the leaching steps in the opposite direction to the circulation of the spent catalyst, each leaching step being followed by a solid / liquid separation step to obtain a solution of extracted metal / metals and a catalyst depleted in metal / metals.

[0013] The process according to the invention makes it possible to ensure a high metal extraction rate as well as reduced consumption of leaching solution compared to a discontinuous process.

[0014] Furthermore, according to one embodiment, the solution of extracted metal(s) can be used as an impregnation solution to prepare a new catalyst as described in FR3117381, i.e. without intermediate treatment where the extracted metal(s) would be in solid phase, nor liquid / liquid extraction treatment thereof.

[0015] According to a variant, the leaching solution / spent catalyst ratio, expressed as mass of leaching solution per mass of spent catalyst to be treated, is between 1 and 15.

[0016] According to a variant, the contacting of the spent catalyst and the leaching solution is carried out by suspension, by fluidization or by percolation of the leaching solution through a fixed bed containing the spent catalyst.

[0017] According to a variant, the circulation of the spent catalyst is carried out by moving baskets, a conveyor belt, a moving grid, an endless screw, or in suspension with the leaching solution, or is simulated by the permutation of the injection point of the leaching solution.

[0018] According to one variant, the solid / liquid separation is carried out by sedimentation, by filtration, by draining and / or by centrifugation.

[0019] According to a variant, the leaching steps are carried out in stirred tanks and the separation steps are carried out with filters.

[0020] According to a variant, the method is implemented with a belt filter on which the spent catalyst is conveyed on a perforated conveyor belt on which it is sprayed with the leaching solution circulating counter-current to the spent catalyst.

[0021] According to this variant, the spent catalyst is supplied in suspension onto the strip by means of a device comprising at least two stirred tanks operating in a permutable mode: when the first tank supplies the strip in suspension, the suspension of the spent catalyst is prepared in the second tank with the solution of leaching coming from the downstream leaching stage, then, when the first tank is empty, the suspension feed to the strip is carried out by the second tank, and the suspension of the used catalyst is prepared in the first tank with the leaching solution coming from the downstream leaching stage.

[0022] According to a variant, the organic compound of the leaching solution has complexing properties, and possibly also acids.

[0023] According to one variant, the organic compound comprises one or more chemical functions chosen from a carboxylic acid, phosphonic acid, sulfonic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide function, or else compounds including a furanic cycle or else sugars.

[0024] According to one variant, the organic compound is chosen from at least one of the following compounds: formic acid, acetic acid, oxalic acid, malonic acid, glutaric acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, γ-ketovaleric acid, succinic acid, acetoacetic acid, gluconic acid, ascorbic acid, phthalic acid, salicylic acid, maleic acid, malic acid, fumaric acid, acrylic acid, thioglycolic acid, 2-hydroxy-4-methylthiobutanoic acid, glutamic acid, N-acetylglutamic acid, alanine, glycine, cysteine, histidine, acid aspartic acid, N-acetylaspartic acid, 4-aminobutanoic acid, 1,2-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA),diethylenetriaminepentaacetic acid (DTPA), bicine, tricine, l-hydroxyethylidene-l,l-diphosphonic acid (HEDP or etidronic acid), ni-trilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), 4-Sulfophthalic acid, 3-(N-morpholino)-2-hydroxy-l-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid.

[0025] According to one variant, the organic compound is chosen from at least one of the following compounds: dimethylglyoxime, methyl acetoacetate, ethyl acetoacetate, ethyl lactate, methyl glycolate, ethyl glycolate, dimethyl malate, diethyl malate, dimethyl tartrate, diethyl tartrate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, methyl 3-methoxypropanoate, methyl 3-(methylthio)propanoate, ethyl 3-(methylthio)propanoate, ethylene glycol, diethylene glycol, triethylene glycol, a polyethylene glycol (with a molecular weight of between 200 and 1500 g / mol), propylene glycol, glycol, glycerol, 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, triethylene glycol dimethyl ether, crown ether, acetophenone, 2,4-pentanedione, pentanone, glucose, fructose, sucrose, sorbitol, xylitol, mannitol, y-valerolactone, propylene carbonate, octylamine, N,N-diethylformamide, N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, propanamide, l-methyl-2-pyrrolidinone, tetramethylurea, N,N'-dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5-hydroxymethylfurfural, 3-hydroxybutanoate ethyl ester, 2-hydroxyethyl acrylate, l-vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'-bis(2-hydroxyethyl)ethylenediamine.

[0026] According to a variant, the concentration of organic compound(s) in the leaching solution is defined so that the molar ratio of organic compound / extracted metal(s), for the organic compound or for each of the organic compound(s) is between 0.2 and 25.

[0027] According to one variant, the used catalyst is subjected to at least one pretreatment step before the first leaching / separation step chosen from deoiling, regeneration, separation of contaminant / impurity type compounds, grinding or even washing with water.

[0028] According to a variant, at least a portion of the extracted metal / metals solution is used as an impregnation solution to prepare a new catalyst comprising a support based on oxide(s), said extracted metal(s) remaining in the liquid phase from extraction until impregnation.

[0029] According to this variant, the solution of extracted metal(s) is subjected to at least one treatment step before impregnation, said treatment step being chosen from a concentration, a dilution and / or a modification of the composition of the solution by addition or elimination, total or partial, of at least one compound from said solution.

[0030] According to a variant, at least part of the impregnation solution is reused after impregnation of said oxide-based support(s) as a supplement to the leaching solution. Definitions

[0031] Within the meaning of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination.

[0032] In the sense of the present invention, the different parameter ranges for a given step such as pressure ranges and temperature ranges may be used alone or in combination. For example, in the sense of the present invention, a preferred range of pressure values ​​can be combined with a preferred range of temperature values.

[0033] In the remainder of the text, the expressions "between ... and..." and "between .... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this were not the case and the limit values ​​were not included in the range described, such precision will be provided by the present invention.

[0034] In this description, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open and does not exclude other elements that are not mentioned. It is understood that the term "comprise" includes the exclusive and closed term "consist".

[0035] In the present description, the term "leaching" is synonymous with the term "extraction", unless otherwise indicated. The term "leaching" or "extraction" in the present description means extracting one or more metals from a solid (spent catalyst) by dissolving it in a liquid (leaching solution or extraction solution).

[0036] In the present description, the term "leaching step" is synonymous with the term "leaching stage", a term often used in the field of leaching.

[0037] According to the present invention, the pressures are absolute pressures, also noted abs., and are given in absolute MPa (or MPa abs.), unless otherwise indicated.

[0038] In the following text, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII (or VIIIB) according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUP AC classification, and group VIB to the metals of column 6.

[0039] The metal content is measured by X-ray fluorescence. List of figures

[0040] [Fig. 1] represents a diagram of the principle of continuous countercurrent leaching.

[0041] [Fig.2] represents a diagram of a first variant of implementation of the method according to the invention with stirred tanks and filters.

[0042] [Fig. 3] represents a first embodiment of a second variant of implementation of the method according to the invention with a band filter.

[0043] [Fig.4] represents a second embodiment of a second variant of implementation of the method according to the invention with a band filter.

[0044] Figures 5 to 8 represent a diagram of a third variant of implementation of the method according to the invention with simulated circulation of the solid.

[0045] The figures are very schematic, do not necessarily represent all the operations that may be involved in the method according to the invention. Identical references from one figure to another refer to the same operation / component / device. Detailed description

[0046] The present invention relates to the recycling of catalyst metals originating in particular from hydrocarbon hydrotreatment or hydroconversion units.

[0047] Hydrotreatment refers to all the purification processes that make it possible to eliminate, by the action of hydrogen, the various impurities contained in hydrocarbon feedstocks. Hydrotreatment processes make it possible to eliminate, by the action of hydrogen, impurities present in the feedstocks such as nitrogen (this is called hydrodenitrogenation), sulfur (this is called hydrodesulfurization), oxygen (this is called hydrodeoxygenation), and compounds containing metals that can poison the catalyst and cause operational problems downstream (this is called hydrodemetalation). Hydrotreatment can thus make it possible to bring the hydrocarbon to the required specifications (sulfur content, aromatics, etc.) for a given application (automobile fuel, gasoline or diesel, domestic fuel oil, etc.).Automotive standards, in particular, have imposed a very strong reduction in sulfur in diesel and gasoline fuels, hydrotreatment thus making it possible to bring these products up to the required specifications.

[0048] Hydrotreatment will therefore improve the quality of hydrocarbons, by reducing the content of certain compounds, elements considered as impurities, but it can also reduce the content of aromatic hydrocarbons, by hydrogenation, and thus improve the cetane index of hydrocarbons. During hydrotreatment processes, fuel gas and light cuts such as LPG (acronym for Liquefied Petroleum Gas) and naphtha can also be produced in small quantities.

[0049] It is recalled that hydrocracking (also referred to as hydroconversion) of heavy hydrocarbon fractions is a key refining process which makes it possible to produce, from excess and poorly recoverable heavy feedstocks, lighter fractions such as gasoline, jet fuels and light diesel fuels which the refiner is looking for to adapt its production to demand. Certain hydrocracking processes also make it possible to obtain a highly purified residue which can constitute excellent bases for oils.

[0050] The hydrocarbon feedstock targeted by hydrotreatment and / or hydroconversion may be of a different nature. The feedstock may in particular be of fossil origin or derived from the conversion of biomass or waste, taken alone or in a mixture. The feedstocks which are treated, and in particular those cited below, generally contain heteroatoms such as sulfur, oxygen and nitrogen and, for heavy loads, they most often also contain metals.

[0051] The feedstock of fossil origin is in particular a cut from coal or hydrocarbons produced from natural gas, possibly in mixtures. It may also be heavy petroleum or synthetic cuts, for example kerosenes, gas oils or distillates from atmospheric and vacuum distillation in order to produce kerosene, gas oil or vacuum distillate which can be recovered, either in the storage unit receiving products of the same type ("pool" in English), or to a downstream unit such as a catalytic cracking unit, where the feedstocks are "cracked" to produce shorter chain hydrocarbons. It is common for the hydrotreatment process to be in fact a preliminary stage of treatment of a feedstock by a hydroconversion / hydrocracking type process.

[0052] The feedstocks of fossil origin used in a hydrotreatment process, in more detail, are for example gasolines, diesel oils, vacuum diesel oils, atmospheric residues, vacuum residues, atmospheric distillates, vacuum distillates, heavy fuels, oils, waxes and paraffins, used oils, residues or deasphalted crudes, feedstocks originating from thermal or catalytic conversion processes, taken alone or in a mixture.

[0053] The feedstock resulting from the conversion of biomass may advantageously be chosen from vegetable oils, algae or algal oils, fish oils, used edible oils, and fats of vegetable or animal origin; or mixtures of such feedstocks. Said vegetable oils may advantageously be crude or refined, totally or partially, and derived from plants chosen from rapeseed, sunflower, soybean, palm, olive, coconut, copra, castor oil, cotton, peanut, linseed and crambe oils and all oils derived for example from sunflower or rapeseed by genetic modification or hybridization, this list not being limiting. Said animal fats are advantageously chosen from lard and fats composed of residues from the food industry or from the catering industries.Frying oils, various animal oils such as fish oils, tallow, lard can also be used. The feedstock resulting from the conversion of biomass can also advantageously be chosen from methyl esters of fatty acids of vegetable and / or animal origin or even methyl esters of fatty acids from used edible vegetable oils.

[0054] The feedstock from the conversion of biomass may also be selected from feedstocks from thermal or catalytic biomass conversion processes, such as oils that are produced from biomass, in particular lignocellulosic biomass, with various liquefaction methods, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to a Material derived from recently living organisms, which includes plants, animals, and their by-products. The term "lignocellulosic biomass" refers to biomass derived from plants or their by-products. Lignocellulosic biomass is composed of carbohydrate polymers (cellulose, hemicellulose) and an aromatic polymer (lignin).

[0055] The feedstock resulting from the conversion of biomass can also advantageously be chosen from feedstocks resulting from the paper industry.

[0056] The feedstock resulting from the conversion of waste can be a pyrolysis oil from plastics, tires or even recovered solid fuels (SRF). These oils are obtained by thermal or catalytic pyrolysis treatment or can be prepared by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

[0057] Conventional hydrotreatment catalysts generally comprise an oxide support and an active phase based on metals from groups VIB and VIII in their oxide forms, as well as phosphorus. The preparation of these catalysts generally comprises a step of impregnation of the metals and phosphorus onto the support, followed by drying and calcination to obtain the active phase in their oxide forms. Before their use in a hydrotreatment and / or hydrocracking reaction, these catalysts are generally also subjected to sulfurization.

[0058] The addition of an organic additive to hydrotreatment catalysts to improve their activity is also known, particularly for catalysts that have been prepared by impregnation followed by drying without subsequent calcination. These catalysts are often referred to as "additive dried catalysts".

[0059] The catalysts used in hydrocracking are of the bifunctional type, i.e. combining an acid function with a hydrogenating function. The acid function is provided by supports with large surfaces (generally 150 to 800 m2.g 1) having significant acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites. The hydrogenating function is provided either by one or more metals from group VIII of the periodic table of elements, or by a combination of at least one metal from group VIB of the periodic table and at least one metal from group VIII, implemented in the presence of sulfur. The balance between the two acid and hydrogenating functions governs the activity and selectivity of the catalyst.

[0060] During its operation in a hydrotreatment or hydrocracking process, the catalyst is deactivated by accumulation of coke and / or sulfur compounds or compounds containing other heteroelements on the surface of the catalyst. Beyond a certain period, its replacement is therefore necessary.

[0061] To combat these drawbacks, the regeneration (also called soft calcination) of hydrotreatment / hydrocracking catalysts is an economically and ecologically interesting process, because it allows these catalysts to be reused in industrial units rather than dumping them or recycling them (metal recovery). Regeneration consists of a heat treatment, generally between 350°C and 550°C, in the presence of pure or diluted oxygen, with the aim of eliminating at least part of the coke present on the spent catalyst by combustion. This regeneration allows the so-called "regenerated" catalyst to recover from the hydrotreatment / hydrocracking activity. But regenerated catalysts are generally less active than the starting catalysts, also called "fresh". As a result, their cycle time in the hydrotreatment / hydrocracking unit is thus reduced compared to that of a fresh catalyst.Eventually, it can be reused in less demanding applications.

[0062] In order to compensate for the lack of hydrotreatment / hydrocracking activity of the regenerated catalyst, it is possible to apply an additional treatment called "rejuvenation". The rejuvenation process consists of re-impregnating the already regenerated catalyst with a solution containing organic or inorganic additives and / or metal precursors. These rejuvenation processes are well known, particularly in the field of middle distillates. Although more efficient than simple regeneration, the rejuvenation of catalysts nevertheless leads in most cases to a catalyst having an activity lower than the fresh catalyst.Finally, some used catalysts cannot be reused via regeneration or rejuvenation, either because their integrity is impaired (too low size or mechanical resistance), or because they contain too large a quantity of contaminants making the performance of the regenerated or rejuvenated product insufficient.

[0063] Although the present invention aims at the recycling of catalyst metals originating in particular from hydrocarbon hydrotreatment or hydroconversion units, it is understood that the process according to the invention applies to any catalyst comprising at least one metal from group VIII and / or at least one metal from group VIB, and an oxide support, such as for example selective hydrogenation catalysts, hydrotreatment catalysts for residues (for example carried out in an ebullated bed) or Fischer-Tropsch catalysts. The spent catalyst

[0064] According to the present invention, the term “spent” catalyst is understood to mean the catalyst from which the metals are to be extracted. The “spent” catalyst is generally an at least partially spent catalyst, i.e. one which has already been used in production, in particular in hydrotreatment or hydroconversion installations of the hydrocracking type. This catalyst may possibly have already been regenerated and / or rejuvenated beforehand. to its recycling. This term also includes a catalyst that has not already been used in production, but which is out of specification, for example because it contains an insufficient metal / metals content, or because of a smaller dimension than the desired one (e.g. "fines" of catalyst particles). This term also includes a capture mass that is at least partially used.

[0065] The spent catalyst of the process according to the invention is a catalyst comprising at least one oxide support and at least one metal, preferably several metals. The spent catalyst comprises at least one metal from group VIII and / or at least one metal from group VIB, an oxide support, and optionally phosphorus. It may also, in a non-limiting manner, comprise coke and / or sulfur as described below.

[0066] The oxide support of said spent catalyst is usually a porous solid chosen from the group consisting of: aluminas, silica, silica-aluminas or titanium or magnesium oxides used alone or in a mixture with alumina or silica-alumina. Preferably, the oxide support is essentially constituted by at least one transition alumina, that is to say that it comprises at least 51% by weight, preferably at least 60% by weight, very preferably at least 80% by weight, or even at least 90% by weight of transition alumina. It is preferably constituted solely by a transition alumina. Preferably, the oxide support of said catalyst is a gamma phase alumina.

[0067] In another preferred case, the oxide present in the support of said spent catalyst is a silica-alumina containing at least 50% by weight of alumina relative to the total weight of the composite support. The silica content in the support is at most 50% by weight relative to the total weight of the support, most often less than or equal to 45% by weight, preferably less than or equal to 40% by weight.

[0068] According to a particularly preferred variant, the support of the used catalyst consists of alumina, silica or silica-alumina.

[0069] The oxide support may also advantageously further contain from 0.1 to 80% by weight, preferably from 0.1 to 50% by weight of zeolite relative to the total weight of the support. In this case, all known zeolite sources and associated preparation methods may be incorporated. Preferably, the zeolite is selected from the FAU, BEA, ISV, IWR, IWW, MEI, UWY group and preferably, the zeolite is selected from the FAU and BEA group, such as Y and / or beta zeolite, and particularly preferably such as USY and / or beta zeolite.

[0070] The support is advantageously in the form of balls, extrudates, pellets or irregular and non-spherical agglomerates whose specific shape can result from a crushing step.

[0071] The oxide support advantageously has a total pore volume of between 0.1 and 1.5 mL / g, preferably between 0.4 and 1.1 mL / g. The total pore volume is measured by mercury porosimetry according to ASTM D4284-92 with a wetting angle of 140°, for example using an Autopore III™ model device from Microméritics™.

[0072] The specific surface area of ​​the oxide support is advantageously between 5 and 400 m2.g *, preferably between 10 and 350 m2.g *, more preferably between 40 and 350 m2.g A. The specific surface area is determined in the present invention by the BET method according to standard ASTM D3663.

[0073] The active phase of the spent catalyst comprises at least one metal from group VIB and / or at least one metal from group VIII. The metal from group VIB present in the active phase of the catalyst is preferably chosen from molybdenum and tungsten, or the mixture of these two elements. The metal from group VIII present in the active phase of the catalyst is preferably chosen from cobalt, nickel and the mixture of these two elements. The active phase of the catalyst is preferably chosen from the group formed by the combination of the elements nickel-molybdenum, cobalt-molybdenum, nickel-cobalt-molybdenum, nickel-tungsten, nickel-molybdenum-tungsten and nickel-cobalt-tungsten.

[0074] The content of group VIII metal is between 1 and 10% by weight of group VIII metal oxide relative to the total weight of the spent catalyst, preferably between 1.5 and 9% by weight, and preferably between 2 and 8% by weight. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively.

[0075] The content of group VIB metal is between 5 and 40% by weight of group VIB metal oxide relative to the total weight of the spent catalyst, preferably between 8 and 35% by weight, very preferably between 10 and 30% by weight. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0076] The molar ratio of group VIII metal to group VIB metal in the catalyst, when the latter contains both types of metals, is preferably between 0.1 and 0.8, preferably between 0.15 and 0.6 and even more preferably between 0.2 and 0.6 or even between 0.3 and 0.5.

[0077] The spent catalyst may also comprise phosphorus as a dopant. The dopant is an added element which, in itself, has no catalytic character but which increases the catalytic activity of the active phase.

[0078] The phosphorus content in said used catalyst is then preferably between 0.1 and 20% by weight expressed as P2O5 relative to the total weight of the used catalyst, preferably between 0.2 and 15% by weight expressed as P2O5, and very preferably between 0.3 and 8% by weight expressed as P2O5.

[0079] The molar ratio of phosphorus to the group VIB element in the catalyst is greater than or equal to 0.05, preferably greater than or equal to 0.07, preferably between 0.08 and 1, preferably between 0.01 and 0.9 and very preferably between 0.15 and 0.6.

[0080] The spent catalyst may comprise sulfur. The sulfur content in said spent catalyst is then preferably between 1 and 15% by weight expressed as an element relative to the total weight of the spent catalyst, preferably between 2 and 12%, and very preferably between 4 and 10% by weight. The sulfur content is measured by elemental analysis according to ASTM D5373.

[0081] The spent catalyst may comprise coke, particularly when it has not been regenerated. It will be noted that the term "coke" in the present application designates a hydrocarbon-based substance deposited on the surface of the catalyst during its use, highly cyclized and condensed and having an appearance similar to graphite.

[0082] The coke content, expressed as % by weight of the carbon element, may be between 2 and 20% by weight, preferably between 3 and 16% by weight and in particular between 4 and 14% by weight relative to the total weight of the spent catalyst. The coke content is determined according to the ASTM D5373 method.

[0083] Optionally, the used catalyst may also have a low content of contaminants from the feedstock treated by the fresh catalyst from which it originates, such as silicon, arsenic, iron, sodium or chlorine, or even sulfur.

[0084] Preferably, the silicon content of the used catalyst (in addition to that possibly present on the fresh catalyst) is less than 2% by weight and very preferably less than 2000 ppm by weight relative to the total weight of the used catalyst.

[0085] Preferably, the arsenic content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the used catalyst.

[0086] Preferably, the chlorine content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the used catalyst.

[0087] Very preferably, the used catalyst, when it is a regenerated catalyst, is not contaminated, that is to say contains a content of less than 100 ppm by weight of silicon (in addition to that possibly present on the fresh catalyst), 100 ppm by weight of sodium (in addition to that possibly present on the fresh catalyst), 50 ppm by weight of arsenic, 50 ppm by weight of iron and 50 ppm by weight of chlorine.

[0088] According to one embodiment of the invention, the spent catalyst may comprise or consist of fines produced during the operation of unloading the spent catalyst from the industrial unit from which it is removed, or during regeneration.

[0089] According to another embodiment, the used catalyst comprises or consists of fines and / or products outside specifications resulting from the various unit operations for manufacturing new catalysts. Pretreatments (optional)

[0090] The spent catalyst may be subjected to at least one pretreatment step prior to leaching according to the method according to the invention. The optional pretreatment step consists of removing all or part of one or more of the impurities possibly contained in said spent catalyst before the metal extraction step, by any method known to those skilled in the art. The pretreatment step may be chosen from deoiling, regeneration, separation of contaminant / impurity type compounds, grinding or even washing with water. Preferably, the pretreatment step comprises a regeneration step to remove all or part of the coke, sulfur and / or chlorine, as detailed below, and / or a heat treatment step under a gas stream containing hydrogen sulfide, carried out in particular to remove arsenic. • Deoiling

[0091] The discharge of the spent catalyst from a hydrotreatment and / or hydrocracking process is preferably preceded by a deoiling step. The deoiling step generally comprises contacting the spent catalyst with a stream of inert gas (i.e. essentially free of oxygen), for example in a nitrogen atmosphere or the like, at a temperature between 300°C and 400°C, preferably between 300°C and 350°C. The flow rate of inert gas in terms of flow rate per unit volume of catalyst is 5 to 150 NL.h 1 for 3 to 7 hours. Alternatively, the deoiling step may be carried out by light hydrocarbons, by steam treatment or any other similar process. • Regeneration

[0092] The used catalyst, possibly de-oiled, can be subjected to a step of removing coke and sulfur: a regeneration step, which makes it possible to remove all or part of the coke, sulfur and / or chlorine possibly deposited on the catalyst.

[0093] Even if this is possible, the regeneration is preferably not carried out by keeping the catalyst loaded in the hydrotreatment reactor (in-situ regeneration). Preferably, the spent catalyst is therefore extracted from the reactor and sent to a regeneration plant in order to carry out the regeneration in said plant (ex-situ regeneration).

[0094] The regeneration step is generally carried out in a gas stream containing oxygen, generally air. The water content in the gas is generally between 0 and 50% by weight. The gas flow rate in terms of flow rate per unit volume of the at least partially spent catalyst is preferably 20 to 2000 NL.h1, more preferably 30 to 1000 NL.h-1, and particularly preferably 40 to 500 NL.h1. The duration of the regeneration is preferably 2 hours or more, more preferably preferably 2.5 hours or more, and particularly preferably 3 hours or more. The regeneration of the spent catalyst is generally carried out at a temperature between 320°C and 550°C, preferably between 360 and 500°C.

[0095] The regenerated catalyst is composed of the oxide support and the active phase formed of at least one metal from group VIB and / or at least one metal from group VIII and optionally phosphorus from the spent catalyst. The regenerated catalyst contains substantially the same content of metal from group VIB and / or VIII as the spent catalyst. The regenerated catalyst is characterized by a specific surface area of ​​between 20 and 300 m2 / g, preferably between 30 and 280 m2 / g, preferably between 40 and 260 m2 / g, very preferably between 80 and 250 m2 / g.

[0096] The pore volume of the regenerated catalyst is generally between 0.1 cmVg and 1.3 cmVg, preferably between 0.2 cmVg and 1.1 cmVg.

[0097] The regenerated catalyst obtained in the regeneration step contains residual carbon at a content of less than 3% by weight relative to the total weight of the regenerated catalyst, preferably between 0% and 2.9% by weight relative to the total weight of the regenerated catalyst, preferably between 0% and 2.0% by weight and particularly preferably between 0% and 1.0% by weight. It will be noted that the term "residual carbon" in the present application means carbon (coke) remaining in the regenerated catalyst after regeneration of the spent catalyst. This residual carbon content in the regenerated catalyst is measured according to the ASTM D5373 method. • Heat treatment under a gas stream containing hydrogen sulfide

[0098] All or part of the elemental arsenic or arsenic compounds potentially contained in the spent catalyst can be removed by passing a stream of hydrogen sulfide and steam or inert gas through the solid at a temperature between 300°C and 750°C. During this treatment, the arsenic contained in the spent catalyst forms arsenic sulfide (of formula As2S3) which is volatilized from the solid. The reaction is preferably carried out by fluidizing the solid in the stream of hydrogen sulfide and steam or inert gas. When a mixture of hydrogen sulfide and inert gas is used, the latter is preferably nitrogen, carbon dioxide or combustion gases.

[0099] This heat treatment step under a gas flow containing hydrogen sulfide is preferably carried out before regeneration. • Grinding

[0100] The spent catalyst, optionally deoiled, regenerated and / or subjected to H2 S treatment, may advantageously undergo, before extraction, an optional grinding step in order to promote the kinetics of extraction of the metals during the process according to the invention. In this case, the step comprises a first optional phase of conditioning the spent catalyst with at least one grinding so as to obtain catalyst particles. having a size of at most 1 mm. It is of course possible to carry out several successive grinding steps in order to achieve the target particle size. Any method known to those skilled in the art can be implemented to carry out this crushing or grinding step, such as for example the use of a ball mill or a blade mill. Preferably, 90% of the volume distribution of the particles of the spent catalyst have an equivalent diameter of between 1 and 1000 micrometers, preferably between 5 and 500 micrometers, more preferably between 10 and 300 micrometers and particularly preferably between 15 and 150 micrometers. The equivalent diameter noted "de" is defined according to the following relationship de=6xV / S with V the volume of the particle and S the surface area of ​​the sphere of the same volume as the particle.

[0101] Most often, the crushed used catalyst is brought into the extraction zone by any means known to those skilled in the art, in particular by a transfer screw or by pneumatic transfer. • Washing with water

[0102] The used catalyst, possibly deoiled, regenerated, subjected to H2S treatment and / or crushed, can undergo a water washing step.

[0103] The volume of water used in this washing step is advantageously greater than the total pore volume of the used catalyst. This volume may in particular be within a range from 2 to 20 times the total pore volume of the used catalyst, preferably between 5 and 10 times said pore volume.

[0104] The washing step may be carried out at any suitable temperature, for example between 5°C and 150°C, preferably between room temperature (20°C) and 70°C.

[0105] During the washing step, it is advantageous to mix the used catalyst so as to ensure efficient washing. The washing step can be carried out in continuous mode or in batch mode, the batch mode being preferred all the more since it makes it possible to limit the quantity of water used. The washing step can be carried out in any unit of the solid / liquid extractor type, or industrial mixer. Leaching process

[0106] The spent catalyst, optionally pretreated, is subjected to the continuous countercurrent leaching process according to the invention which comprises N leaching steps, N being greater than or equal to 2, by countercurrent contacting of the spent catalyst with a leaching solution comprising at least one organic compound, each leaching step being followed by a solid / liquid separation step, to obtain a solution of extracted metal / metals and a catalyst depleted in metal / metals.

[0107] The method according to the invention is characterized by the fact that the leaching solution is fed continuously and passes through the different stages in the opposite direction to the circulation of the solid, i.e. the used catalyst.

[0108] [Fig.l] provides an illustration of the process according to the invention. Each numbered block (1, 2, .. .N) represents a leaching step (or stage) by bringing the solid into contact with the leaching solution, then the solid-liquid separation. The spent catalyst circulates from step 1 to step N. The leaching solution circulates in the opposite direction, from step N to step 1.

[0109] In this way, the fresh solid CR (i.e. the spent catalyst with the highest metal loading) always first sees the solution most enriched in metals, then additional steps of leaching / separation of the catalyst increasingly leached of these metals are followed by solutions less and less loaded with extracted metals until the last step (step N) using the leaching solution free of metals SP. In this way, a solution enriched with extracted metal / metal(s) SR and a catalyst depleted in metal / metals CP are recovered. This principle ensures a higher metal concentration of the final solution.

[0110] The method according to the invention comprises N leaching steps, N being greater than or equal to 2. Advantageously, it comprises between 2 and 20 leaching / separation steps, preferably between 2 and 6 steps. Each step makes it possible to bring the liquid and the solid into contact and then to carry out a liquid / solid separation.

[0111] The contacting of the liquid and the solid can be done by any method known to those skilled in the art, for example by suspending the used catalyst in the leaching solution by means of a rotating stirrer or by fluidization, or by percolation of the leaching solution through a fixed bed containing the used catalyst.

[0112] The circulation of the solid can be carried out by any method known to those skilled in the art, for example by moving baskets, a conveyor belt, a moving grid, an endless screw or in suspension with the leaching solution (also called "slurry" according to English terminology). The circulation of the solid can also be simulated by permuting the injection point of the leaching solution. Indeed, if the injection point is moved periodically from step i to i+1, the solid moves in the opposite direction to the liquid, relative to its injection point.

[0113] The liquid / solid separation can be carried out by any method known to those skilled in the art, for example by sedimentation, by filtration, by draining, for example by gravity, and / or by centrifugation.

[0114] The method according to the invention can be carried out according to different variants. These different variants are described below.

[0115] According to a first variant, the method according to the invention can be implemented with stirred tanks and filters. Each leaching / separation step comprises a stirred tank and a filter. [Fig. 2] shows a diagram of the first implementation variant of the process according to the invention comprising 3 leaching / separation stages with stirred tanks and filters. In the figure, the solid arrows represent the catalyst, the dotted lines the leaching solution and the dashed lines the slurry.

[0116] The spent catalyst CR is introduced, preferably in crushed form, into the stirred tank RI where it is suspended in the liquid S2. The slurry formed SRI is sent to a filter F1 which separates the liquid and the solid. The catalyst cake C1 obtained is sent to the tank R2 where it is redispersed and suspended in the liquid SL. The slurry SR2 withdrawn from the bottom of the tank R2 is sent to a filter F2, which separates a new catalyst cake C2 sent to the tank R3. The depleted catalyst CP is finally recovered at the outlet of the filter F3 fed by the slurry SR3 withdrawn from the bottom of the tank R3. The catalyst therefore travels through the process in the direction RI to R3.

[0117] Conversely, the leaching solution SP continuously feeds the tank R3. The filtrate SI recovered in the filter F3 is returned to the tank R2 forming a slurry SR2 feeding the filter F2 whose filtrate S2 is returned to the tank RL. The slurry formed SRI in the tank RI is separated in the filter F1 and the filtrate thus recovered constitutes the final enriched solution SR. The leaching solution therefore travels through the process in the direction R3 towards RL.

[0118] According to a second variant, the method according to the invention can be implemented with a belt filter. In this case the catalyst is conveyed, preferably in ground form, on a perforated conveyor belt on which it is sprayed with leaching solution circulating counter-current to the solid.

[0119] According to a first embodiment of this second variant, shown in [Fig. 3], the spent catalyst CR (solid) is loaded onto the conveyor belt using a device ensuring a controlled and uniform solid height across the width of the belt. Once loaded, the solid advances with the movement of the belt. During its travel, the solid passes through several (N) extraction zones or stages (3 zones in [Fig. 3]) in which it is sprayed with leaching solution by a spray nozzle. The metal-free leaching solution SP is introduced at the end of the conveyor belt. A vacuum is in place under the belt to force the liquid to percolate through the solid. The liquid is recovered in a tank located under the belt and constitutes a solution enriched in metallic species following contact with the solid. This solution is returned by a pump to the upstream extraction zone.In this way, the leaching solution is countercurrent to the solid circulation. The solution recovered closest to the fresh solid feed constitutes the final solution enriched in SR metal species. At the other end of the belt, the depleted solid CP is . unloaded, using a scraper for example.

[0120] According to a second embodiment of this second variant, shown in [Fig.4], the spent catalyst CR (solid) is fed with slurry onto the belt, by means of a device consisting of two stirred tanks operating in a permutable mode (also called "swing", according to the established Anglo-Saxon term). A first tank RI receives the solid and the leaching solution coming from the downstream extraction zone, the outlet of the tank being closed. During this time the second tank R2 feeds the conveyor belt with slurry. When it is empty, the feed is done by the first tank RI and the second tank R2 receives the solid and the leaching solution. This device ensures a continuous slurry feed to the conveyor belt. The metal-free leaching solution SP is introduced at the end of the conveyor belt. The first lengths of the belt see a cake form as the liquid percolates through the solid.The solid advances with the movement of the belt and passes through several (N) extraction zones or extraction stages (3 zones in [Fig.4]). In the last N1 zones, it is sprayed with leaching solution by a spray nozzle. The liquid is collected in a tank located under the belt and constitutes a solution enriched in metallic species following contact with the solid. Said solution recovered under the belt in one of the last N-2 extraction zones is returned by a pump to the upstream extraction zone. In this way, the leaching solution is countercurrent to the solid circulation. The solution recovered at the first zone or extraction stage closest to the fresh solid feed constitutes the final SR solution enriched in metallic species. The solution recovered at the second zone or extraction stage is returned by a pump to the stirred tank whose outlet is closed to prepare the slurry.At the other end of the belt, the depleted solid CP is discharged, using a scraper for example. This second embodiment is preferred because the agitation maintained in the slurry feed tank ensures sufficient suspension of the fines which avoids forming a layer of fines on the belt, the latter being able to be problematic for the filtration properties.

[0121] According to a third variant, the method according to the invention can be implemented with a simulated circulation of the spent catalyst (solid). Figures 5 to 8 represent a diagram of this third implementation variant in which the circulation of the solid is done by permutation of the injection of the fresh leaching solution, with 3 leaching / separation steps in 4 columns containing the catalyst, one of which is for the unloading of the leached catalyst / loading of the fresh spent catalyst. The dotted arrows represent the path of the leaching solution. The spent catalyst (solid) is introduced, preferably in the form of extrudates, into columns, named RI to R4. The solid / liquid separation step is done intrinsically sequentially in each of the columns by liquid flow.

[0122] During step 1 of this embodiment ([Fig.5]), the fresh leaching solution SP is injected at the top of column R2 and percolates through the catalyst bed, before passing through column R3 and then column R4. The enriched solution SR is withdrawn at the bottom of R4. During this time, column RI is offline in order to discharge the depleted spent catalyst CP and recharge a spent catalyst to be treated CR.

[0123] During step 2 of this embodiment ([Fig.6]), the injection of leaching solution SP is now done at the top of column R3 and column R2 is in unloading Cp / reloading CR. Relative to the injection point, the catalyst has moved in the opposite direction to the liquid circulation, with a solid flow rate equal to the mass of catalyst contained in a column divided by the permutation time. The permutation time between each step is generally between 1 min and 24 h.

[0124] The reloaded spent catalyst CR in step 1 therefore first sees the most enriched solution coming from column R4, making it possible to draw off a concentrated enriched solution SR at the bottom of RL

[0125] Similarly, during step 3 of this embodiment ([Fig.7]), the injection of the leaching solution SP is done at the top of column R4 and at the top of column C1 during step 4 of this embodiment ([Fig.8]). Then, the cycle starts again according to [Fig.5].

[0126] According to the method according to the invention, the used catalyst is brought into contact with a leaching solution containing at least one organic compound.

[0127] The leaching solution according to the present invention may comprise any polar protic solvent known to those skilled in the art. Preferably, a polar protic solvent is used, for example chosen from the group formed by methanol, ethanol, and water, or a water-ethanol or water-methanol mixture. Very preferably, the solvent used consists of water. In the case of an aqueous solution, the pH of said solution may be modified by the possible addition of an acid or a base. The extraction solution has a pH generally between 0.1 and 8.5, preferably between 0.5 and 6, preferably between 1 and 4.

[0128] Preferably, the extraction of the metals is carried out with a solution comprising a solvent, in particular aqueous, and at least one organic compound having complexing properties, and possibly also acids (either at least one compound having both properties, or the combination of at least one acid compound and at least one complexing compound, or only at least one complexing compound for example).

[0129] It has indeed been found that adding an organic compound to the solution (generally aqueous) is very effective in extracting the metals of interest that we want to recycle, by making them pass into the liquid phase, while the support of the used catalyst and any other components of the used catalyst remain in the solid phase and are thus easily removable.

[0130] It should be emphasized that the organic compounds which give the most interesting results are compounds with acidic and complexing properties. Indeed, an organic acid makes it possible to protonate the metal oxide, thus limiting its interaction with the support and promoting its dissolution in the extraction solution. A complexing agent makes it possible to form a metal complex soluble in the extraction solution. The combination of acidic and complexing properties is therefore particularly interesting: the use of an organic compound having these two properties or the association of an acidic organic compound and a complexing organic compound is therefore particularly indicated.

[0131] This organic compound, or at least one of them when there are several, can comprise one or more chemical functions chosen from a carboxylic acid, phosphoric acid, sulfonic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide function, or even compounds including a furanic cycle or even sugars.

[0132] The organic compound (or at least one of them when there are several) having both acidic and complexing properties can be chosen from at least one of the following compounds: formic acid, acetic acid, oxalic acid, malonic acid, glutaric acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, γ-ketovaleric acid, succinic acid, acetoacetic acid, gluconic acid, ascorbic acid, phthalic acid, salicylic acid, maleic acid, malic acid, fumaric acid, acrylic acid, thioglycolic acid, 2-hydroxy-4-methylthiobutanoic acid, glutamic acid, N-acetylglutamic acid, alanine, glycine, cysteine, histidine, aspartic acid, N-acetylaspartic acid, 4-aminobutanoic acid, 1,2-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA),iminodiacetic acid (IDA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), bicine, tricine, l-hydroxyethylidene-l,l-diphosphonic acid (HEDP or etidronic acid), ni-trilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), 4-Sulfophthalic acid, 3-(N-morpholino)-2-hydroxy-l-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid.

[0133] The organic compound (or at least one of them when there are several) having complexing properties can be chosen from at least one of the following compounds: dimethylglyoxime, methyl acetoacetate, ethyl acetoacetate, ethyl lactate, methyl glycolate, ethyl glycolate, dimethyl malate, diethyl malate, dimethyl tartrate, diethyl tartrate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, methyl 3-methoxypropanoate, methyl 3-(methylthio)propanoate, ethyl 3-(methylthio)propanoate, ethylene glycol, diethylene glycol, triethylene glycol, a polyethylene glycol (with a molecular weight between 200 and 1500 g / mol), propylene glycol, glycerol, 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, triethylene glycol dimethyl ether, a crown ether, acetophenone, 2,4-pentanedione, pentanone, glucose, fructose, sucrose, sorbitol, xylitol, mannitol, y-valerolactone, propylene carbonate, octylamine, N,N-diethylformamide, N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, propanamide, l-methyl-2-pyrrolidinone,tetramethylurea, N,N'-dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5-hydroxymethylfurfural, ethyl 3-hydroxybutanoate, 2-hydroxyethyl acrylate, l-vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'-bis(2-hydroxyethyl)ethylenediamine.

[0134] Preferably, the organic compound is chosen from a carboxylic acid which preferably comprises between 1 and 8 carbon atoms and which may be a mono-acid, di-acid or tri-acid. Preferably, the organic compound is chosen from formic acid, acetic acid, glutaric acid, oxalic acid, glycolic acid, lactic acid, citric acid, γ-ketovaleric acid, acetoacetic acid, gluconic acid and ascorbic acid.

[0135] The concentration of each organic compound in the leaching solution is defined so that the molar ratio of organic compound to extracted metals is between 0.2 and 25, preferably between 0.2 and 11, preferably between 0.2 and 5, preferably between 0.4 and 2, and preferably between 0.4 and 1.2.

[0136] When several organic compounds are present, the different molar ratios apply for each of the organic compounds present.

[0137] The concentration of organic compound in the leaching solution is generally between 5 and 300 g / L, preferably between 15 and 200 g / L.

[0138] In one embodiment according to the invention, the leaching solution may also contain phosphorus. The presence of phosphorus promotes the extraction of metals, and in particular molybdenum, due to the high stability of the heteropolyanions that this metal forms with phosphorus. The addition of phosphorus in the form of phosphoric acid H3PO4 also makes it possible to lower the pH of the solution, which is also generally beneficial for the extraction of metals contained in the spent catalyst. Mineral acids other than phosphoric acid may also be used. phoric acid, in particular nitric acid, sulfuric acid or boric acid.

[0139] In one embodiment according to the invention, the leaching solution may also contain an oxidant to promote the extraction of metals. Preferably, the oxidant contained in the leaching solution is hydrogen peroxide. When an oxidant is present, the concentration is generally between 0.1 and 5.0 mol / L.

[0140] Generally speaking, the operating conditions of the process according to the invention are chosen so as to maximize the extraction of the metals contained in the spent catalyst, while minimizing the dissolution of the metal(s) contained in the support of said spent catalyst, and by limiting the quantity of organic compound so that the latter is not in too great an excess compared to the optimal quantity of organic compound possibly necessary for the impregnation step to obtain high-performance catalysts. It is also sought to minimize the quantity of extraction solution to be used, in order to obtain the most concentrated metal solution possible at the end of extraction: this limits the need to concentrate the solution before possibly using it in the impregnation solution or as an impregnation solution.

[0141] Contact is carried out with the extraction solution under the following conditions:

[0142] The temperature is generally between 0 and 300°C, preferably between 10 and 100°C, and more preferably between 15 and 40°C. Particularly preferably, the temperature is room temperature.

[0143] The pressure is generally between atmospheric pressure and 20 bars (2 MPa), in particular between atmospheric pressure and 10 bars (1 MPa).

[0144] The contact time is generally between 1 minute and 20 hours, preferably between 5 and 300 minutes, and more preferably between 5 and 180 minutes.

[0145] When the tool(s) performing the contacting do not have heating equipment, and the temperature of the contacting is regulated by the temperature of the extraction solution. It can therefore be at room temperature, or have been heated, for this specific contacting step. It can also be at a given temperature, in particular above room temperature, because it comes, at least in part, from the recycling of liquid effluents produced during its possible use as an impregnation solution and already being in this temperature range.

[0146] The quantity of leaching solution used for the process according to the invention is preferably as low as possible to obtain the desired effect, as indicated above. Preferably, the liquid / solid ratio, expressed as mass of leaching solution per mass of used catalyst to be treated, is between 1 and 15, preferably between 2 and 12, preferably between 3 and 10.

[0147] According to one embodiment, when the spent catalyst contains only one metal from group VIB or one metal from group VIII respectively, a fortiori only one metal from group VIB or one metal from group VIII is extracted from the catalyst. According to another embodiment, when the spent catalyst contains both at least one metal from group VIB and at least one metal from group VIII, and either only the metal from group VIB or from group VIII respectively, or both the metal from group VIB and the metal from group VIII are extracted.

[0148] At the end of the leaching step, the solution is separated from the solid residue to obtain, on the one hand, a leached catalyst depleted in metal / metals, and, on the other hand, the leaching solution enriched in at least one metal from group VIB and / or at least one metal from group VIII.

[0149] The liquid / solid separation can be carried out by any method known to those skilled in the art, for example by sedimentation, by filtration, by draining, for example by gravity, and / or by centrifugation.

[0150] Preferably, the residual metal content of the metal / metal depleted catalyst (sum of the contents of the different metals contained in the leached catalyst expressed as oxide) is less than 10% by weight, preferably less than 5% by weight and very preferably less than 2% by weight relative to the weight of the metal / metal depleted catalyst.

[0151] The leaching rate is generally greater than 50%, preferably greater than 60%, more preferably greater than 70%. The leaching rate corresponds to the mass of the metal / metals extracted in the final solution relative to the mass of metal / metals initially present on the spent catalyst. Valorization of the leaching solution

[0152] According to one embodiment, the extracted metal or metals contained in the extracted metal / metals solution may be recovered in solid form. The recovery in solid form may be carried out by any method known to those skilled in the art, for example by precipitation / filtration, crystallization / filtration or a liquid / liquid extraction treatment followed by evaporation of the solvent, or by adsorption on capture mass.

[0153] According to another preferred embodiment, the extracted metal / metals solution can be used as an impregnation solution to prepare a new catalyst as described in FR3117381, i.e. without intermediate treatment where the extracted metal(s) would be in solid phase, nor liquid / liquid extraction treatment thereof. In this case, the extracted metal(s) contained in the extracted metal / metals solution remain in solution until they are reused as an additional impregnation solution to produce a new catalyst. This allows a valo "direct" rization, thus saving a quantity of precipitation / filtration type operations allowing the production of a new catalyst which is easy to implement on an industrial scale. It is further simplified when the leaching solution and the impregnation solution have a solvent (or mixture of solvents) in common, in particular when the solvents of the two solutions are identical (or similar, except for the proportion of solvents, for example, in the case of a mixture of solvents).

[0154] Before its use as an impregnation solution, the solution of extracted metal(s) may be subjected to at least one treatment step chosen from at least one of the following treatments: purification, concentration, dilution, modification of the composition of the solution by addition or elimination, total or partial, of at least one compound. The extracted metal(s) remain in the liquid phase during these treatments. • Purification

[0155] The extracted metal / metals solution may be subjected to a purification step. The role of purification is to remove all or part of the impurities possibly contained in the metal solution, in particular from impurities potentially present on the used catalyst or linked to a partial dissolution of the support of said catalyst. The purification may take place in a single step or in several successive steps.

[0156] In the case where the extracted metal / metals solution contains suspended solids after the last liquid / solid separation step, any known method for removing these suspended materials may be used. Preferably, this removal is carried out by filtration (for example, microfiltration and ultrafiltration on a cross-flow filter). Other methods are centrifugation, coagulation, or sedimentation.

[0157] For dissolved impurities, such as for example arsenates or arsenites, all known methods may be used, in particular and preferably, sorption on solid, precipitation and extraction by solvent, taking care not to remove at the same time the metals of interest which have been extracted. • Concentration

[0158] The extracted metal / metal solution, optionally purified, may be subjected to a concentration step. This step consists of concentrating the extracted metal / metal solution, by removing part of the solvent, and optionally all or part of the organic compound contained in the metal solution. This step may be necessary if the metal concentrations are too low compared to the concentrations necessary to carry out impregnation. Any known method for removing part of a solvent from a solution is envisaged. The concentration may take place in a single step or in several successive steps. All or part of the solvent containing or not containing organic compound, extracted from the metal solution, can be recycled in the process according to the invention as a leaching solution.

[0159] Preferably, and in particular in the case where the metal solution is an aqueous solution, the concentration is carried out by evapoconcentration. In this case, neutralization will preferably be carried out, so that the effluent enters the evaporator in a pH range of 5 to 7. This pH regulation makes it possible to limit co-distillation phenomena, unless this is sought for the co-elimination of the solvent and part of the organic compound and, moreover, to avoid as much as possible the precipitation of metal oxides. Preferably, all or part of the distillate can be recycled in the process according to the invention as a leaching solution.

[0160] When only the removal of a portion of the solvent is desired, in addition to evaporation concentration, the preferred techniques are membrane techniques, and, very preferably, nanofiltration, reverse osmosis and pervaporation, solvent extraction or cryoconcentration.

[0161] When it is desired to remove solvent and organic compound(s) when used, a preferred technique is evapoconcentration. • Adjustment of the composition of the metal solution

[0162] The extracted metal / metal solution(s), optionally purified and / or concentrated, may be subjected to a composition adjustment step. This step consists of modifying the metal solution by adding(s) and / or removing(s) certain constituents. Metal precursors and / or phosphorus precursors and / or organic additives may be added. Organic compounds used for the extraction of the metals may also be removed, in whole or in part, if necessary. The objective is to obtain a metal solution whose composition corresponds to that desired for the impregnation solution used for the synthesis of a new catalyst.

[0163] The adjustment of the ratios between metals is done either by adding a make-up solution containing one or more of said metals, or by direct dissolution of one or more metal precursors in the extracted metal / metal solution(s), the latter alternative being preferred. The molar ratio of group VIII metal to group VIB metal in the metal solution at the end of this adjustment step is generally between 0.1 and 0.8, preferably between 0.15 and 0.6.

[0164] As an example for the metal precursors, among the sources of molybdenum, it is possible to use oxides and hydroxides, molybdic acids and their salts, in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H3PMO12O40), and their salts, and even molybdenum is most commonly silicomolybdic acid (H4SiMo2O4o) and its salts. Molybdenum sources can also be any heteropolycompound of the Keggin, Keggin lacunary, Keggin substituted, Dawson, Anderson, Strandberg type, for example. Molybdenum trioxide and heteropolycompounds of the Keggin, Keggin lacunary, Keggin substituted and Strandberg type are preferably used.

[0165] The tungsten precursors that can be used are also well known to those skilled in the art. For example, among the sources of tungsten, it is possible to use oxides and hydroxides, tungstic acids and their salts, in particular ammonium salts such as ammonium tungstate, ammonium metatungstate, phosphotungstic acid and their salts, and optionally silicotungstic acid (H4SiWi204o) and its salts. The sources of tungsten can also be any heteropolycompound of the Keggin, vacated Keggin, substituted Keggin, Dawson type, for example. Preferably, ammonium oxides and salts such as ammonium metatungstate or heteropolyanions of the Keggin, vacated Keggin or substituted Keggin type are used.

[0166] The cobalt precursors that can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. Cobalt hydroxide and cobalt carbonate are preferably used. It can also be cobalt acetoacetate.

[0167] The nickel precursors which can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. It can also be nickel acetoacetate.

[0168] A phosphorus precursor may be used for the leaching process according to the invention. If the phosphorus / metal ratio of the extracted metal / metal solution is lower than that desired for the impregnation solution, a phosphorus precursor, identical or different from that optionally used for leaching, may be added to the extracted metal / metal solution. This will be the case in particular when no phosphorus compound / precursor has been added to the leaching, or when it has been consumed at least in part by the support, when it contains alumina, to form alumino-phosphates. In this case, the molar ratio of phosphorus to the group VIB metal is between 0.1 and 2.5 mol / mol, preferably between 0.1 and 2.0 mol / mol, and even more preferably between 0.1 and 1.0 mol / mol or between 0.15 and 0.8 mol / mol, or between 0.2 and 0.6 mol / mol.

[0169] The preferred phosphorus precursor is phosphoric acid H3PO4, but its esters and salts such as ammonium phosphates are also suitable, as are polyphosphates. Phosphorus may also be introduced together with the group VIB element(s) in the form of Keggin, vacated Keggin, substituted Keggin or Strandberg-type heteropolyanions.

[0170] Addition of an organic additive to hydrotreatment / hydrocracking catalysts has been recommended by those skilled in the art to improve their activity. They are known to improve the dispersion of metals on the surface of the support and / or to play a beneficial role during the sulfurization of catalysts. Thus, one or more organic additives well known to those skilled in the art can be advantageously added at this stage. Generally, the quantity of each organic additive added is defined so that the additive / metal molar ratio is between 0.1 and 1 in the impregnation solution.

[0171] Patent FR3083134 describes examples of organic additives that may be suitable and that can be used in aqueous form, and that can therefore be added to the impregnation solution. Patent FR3083131 also describes examples of organic additives that may be suitable, but which will rather be added separately, in pre-impregnation or post-impregnation of the support.

[0172] The extracted metal / metal solution may contain an excess of organic compound compared to the desired impregnation solution. The ratios between organic compound and metals can be adjusted in two ways. The first way consists of adding a concentrated solution of metal precursors, or of directly dissolving these metal precursors in order to achieve the desired ratios. In this case, the final catalyst obtained will comprise a mixture of recycled metals and new metals.

[0173] If the excess of organic compound is too great to use the first method (i.e. the quantity of recycled metals incorporated in the final catalyst is not significant, for example less than 5% of the total quantity of metals), the second method then consists of removing all or part of the excess organic compound from the metal solution. In this case, the organic compound can be recycled to the leaching process according to the invention. For this, any method known to those skilled in the art for separating an organic molecule from a metal solution is envisaged. The concentration of excess organic compound can be reduced for example by evaporation, by liquid-liquid extraction, by adsorption or by membrane separation.

[0174] The extracted metal / metal solution, possibly previously subjected to one or more of the treatments described below, can be used for the preparation of a new catalyst. For this, an oxide support, or a catalyst already containing one or more metals, is brought into contact with the extracted metal / metal solution. The contacting can be carried out by any known method, such as for example ion exchange, dry impregnation, excess impregnation, vapor deposition, etc. The contacting can take place in one step or in several successive steps.

[0175] The oxide support which will be impregnated with the impregnation solution resulting from the solution of extracted metal(s) can be of the same nature as the support of the used catalyst, a description of which has already been given above.

[0176] A catalyst already containing one or more metals can also be brought into contact with the solution of extracted metal(s). This may be a catalyst that has been depleted of metals, and in particular be a used catalyst itself, possibly regenerated and then optionally rejuvenated.

[0177] According to a preferred embodiment, the contacting of said support with the metal solution is carried out by excess impregnation or by dry impregnation. Equilibrium or excess impregnation consists of immersing the support or the catalyst in a volume of solution (often largely) greater than the pore volume of the support or the catalyst. Dry impregnation consists, for its part, of introducing a volume of impregnation solution equal to or slightly less than the pore volume of the support or the catalyst. Dry impregnation makes it possible to deposit on a given support or catalyst all of the constituents of the impregnation solution. The contacting can advantageously be carried out by one or more excess impregnations of solution or preferably by one or more dry impregnation(s), and, for example, by a single excess impregnation, using the impregnation solution.

[0178] The impregnation is carried out at a temperature generally between 10°C and 95°C, at a pressure between atmospheric pressure and 20 bars (2 MPa), preferably at atmospheric pressure, and for a duration preferably between 1 minute and 20 hours, preferably between 1 and 300 minutes. The impregnation is preferably carried out at a temperature between 10°C and 60°C, preferably at room temperature.

[0179] Advantageously, after each impregnation step, the impregnated support or catalyst is allowed to mature. Maturation allows the impregnation solution to disperse homogeneously within the support or catalyst.

[0180] Any maturation step is advantageously carried out at atmospheric pressure, in a water-saturated atmosphere and at a temperature between 17°C and 50°C, and preferably at room temperature. Generally, a maturation time of between 10 minutes and 48 hours, and preferably between 30 minutes and 6 hours, is sufficient.

[0181] Advantageously, the contacting step is followed by a drying step at a temperature below 200°C, preferably between 50 and 180°C, more preferably between 70 and 150°C, and very preferably between 75 and 130°C. The drying step is preferably carried out for a period of between 10 minutes and 24 hours. Longer periods are not excluded, but do not necessarily provide an improvement. The drying step can be carried out by any known technique. It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out at atmospheric pressure. It is advantageously carried out using air or any other hot gas. Preferably, the gas used is either air or an inert gas such as argon. or nitrogen. Very preferably, the drying is carried out in the presence of nitrogen and / or air and is advantageously carried out in a crossed bed.

[0182] According to a variant, the drying is advantageously carried out so as to preferably retain at least 30% by weight of the organic additive introduced during a possible adjustment of organic compound and / or during the impregnation step. Preferably this quantity is greater than 50% by weight and even more preferably, greater than 70% by weight, calculated on the basis of the carbon remaining on the catalyst.

[0183] Optionally, the drying may be followed by a calcination step. This may be the case, for example, if it is desired to eliminate all or part of one or more organic extraction compounds. According to this variant, at the end of the drying step, a calcination step is carried out at a temperature between 200°C and 600°C, preferably between 250°C and 550°C, under an inert atmosphere (nitrogen for example) or under an atmosphere containing oxygen (air for example). The duration of this heat treatment is generally between 0.5 hours and 16 hours, preferably between 1 hour and 5 hours. After this treatment, the active phase is thus generally in oxide form, the heteropolyanions are thus transformed into oxides. Similarly, the catalyst no longer contains or contains very little organic extraction compound and organic additive.However, the introduction of the organic additive during its preparation made it possible to increase the dispersion of the active phase, thus leading to a more active catalyst.

[0184] Preferably, the catalyst is not subjected to calcination.

[0185] In the embodiment in which the impregnation step is carried out via at least two impregnation cycles, each impregnation is advantageously followed by drying and possibly calcination.

[0186] The quantity of recycled metals contained in the new catalyst is between 1% and 100% by weight of the metals contained in the new catalyst, preferably between 10% and 100% by weight, preferably between 20% and 100% by weight, and even more preferably between 50% and 100% by weight relative to the weight of the new catalyst.

[0187] It should be noted that the new catalyst may have a different formulation from the spent catalyst used to recover the metals and different quantities of metal and different ratios between metals: thus, a spent catalyst highly loaded with metals may, according to the invention, be used to produce a catalyst with a lower metal load (or vice versa). This makes it possible, where appropriate, to avoid a step of concentrating the solution after extraction or at least to reduce its intensity / duration.

[0188] It should also be noted that the new catalyst can be post-additive, that is to say that an additional impregnation step of one or more organic additives can be carried out, the function of which is to increase the catalytic activity compared to the ca non-additive catalysts, before the final optional sulfurization, it being understood that, preferably, no calcination step is carried out after its introduction.

[0189] Before use, the new catalyst may undergo an optional sulfurization step. The sulfurization is preferably carried out in a sulforeducing medium, i.e. in the presence of H2S and hydrogen, in order to transform the metal oxides into sulfides such as, for example, MoS2 and Co9S8. The sulfurization is carried out by injecting onto the catalyst a stream containing H2S and hydrogen, or a sulfur compound capable of decomposing into H2S in the presence of the catalyst and hydrogen. Polysulfides such as dimethyl disulfide (DMDS) are H2S precursors commonly used to sulfurize catalysts. The sulfur can also come from the feedstock. The temperature is adjusted so that H2S reacts with the metal oxides to form metal sulfides.This sulfurization can be carried out in situ or ex situ (inside or outside the reactor) of the reactor of the hydrotreatment or hydroconversion process according to the invention at temperatures between 200 and 600°C, and more preferably between 300 and 500°C. Examples

[0190] The solid to be treated is a previously ground regenerated CoMoP hydrotreatment catalyst, 90% of whose volume particle size distribution has a size less than 150 microns (qm) and containing 21% by weight of molybdenum (expressed as MoO3 oxide). The leaching solution is a solution of water and glutaric acid at a concentration equal to 180g / L. The extraction is carried out at 20°C and with a liquid / solid ratio (or leaching solution / catalyst) equal to 3 kg / kg.

[0191] In this example, the process according to the invention, called process B, is compared to a batch process with one extraction, called process A1, as well as to a batch process with two extractions, called A2.

[0192] In the Al process (comparative), the solid to be treated is introduced into a stirred tank filled with leaching solution and is kept stirred for 60 minutes. The slurry is then sent to a frontal filtration under a vacuum of 0.5 bars (0.05 MPa), with a cut-off threshold of 20 microns (qm). The recovered filtrate constitutes the final solution enriched in molybdenum and cobalt.

[0193] In process A2 (comparative), the solid to be treated is introduced into a stirred tank filled with leaching solution and is kept stirred for 60 minutes. The slurry is then sent to a front filtration under a vacuum of 0.5 bar (0.05 MPa), with a cut-off threshold of 20 microns (qm). The recovered filtrate is sent to the product storage. The depleted cake is returned to the stirred tank and is brought back into contact with a metal-free leaching solution for 60 min. The resulting slurry is sent to a front filtration under a vacuum of 0.5 bar (0.05 MPa), with a cut-off threshold of 20 microns (iim). The recovered filtrate is sent to product storage and is mixed with the filtrate obtained in the previous step to form the final solution.

[0194] Method B is a method according to the invention with an implementation on a conveyor belt fed with slurry. The vacuum under the belt is maintained at 0.5 bar (0.05 MPa) and the filter media has a cut-off threshold of 20 microns (pm). The cake formed has a thickness of 10 mm. The belt moves at a speed of 1 m / min and the residence time of the solid on the belt is 20 min. The process passes through 2 extraction zones arranged in counter-current and watering the liquid according to a liquid / solid ratio (or leaching solution / catalyst) equal to 3 kg / kg. The final solution is collected under the belt, on the slurry feed side.

[0195] Performance is viewed in terms of molybdenum extraction rate and leaching solution consumption. The extraction rate corresponds to the mass of molybdenum extracted in the final solution relative to the mass of molybdenum initially present on the catalyst. The leaching solution consumption is expressed in liters of solution required per kg of molybdenum extracted. The process performances are summarized in Table 1.

[0196] [Tables 1] Extraction rate (%) Leaching solution consumption (L / kg) Process Al (comparative) 54.5 39.3 Process A2 (comparative) 83.2 51.5 Process B (according to the invention) 76.7 27.9

[0197] Compared to process A1, process B according to the invention ensures a higher extraction rate, as well as reduced consumption of leaching solution.

[0198] Compared to process A2, process B according to the invention ensures reduced consumption of leaching solution while ensuring a high extraction rate.

Claims

Claims

1. Continuous process for countercurrent leaching of a spent catalyst comprising at least one metal from group VIB, and / or at least one metal from group VIII, optionally phosphorus and / or sulfur, and a support based on oxide(s), characterized in that said process comprises N leaching steps, N being greater than or equal to 2, by countercurrently contacting the spent catalyst with a leaching solution comprising at least one organic compound, the leaching solution being fed continuously and passing through each of the leaching steps in the opposite direction to the circulation of the spent catalyst, each leaching step being followed by a solid / liquid separation step to obtain a solution of extracted metal / metals and a catalyst depleted in metal / metals.

2. The method of claim 1, wherein the leaching solution / spent catalyst ratio, expressed as mass of leaching solution per mass of spent catalyst to be treated, is between 1 and 15.

3. A method according to any preceding claim, wherein the contacting of the spent catalyst and the leaching solution is carried out by suspending, fluidizing or percolating the leaching solution through a fixed bed containing the spent catalyst.

4. A method according to any preceding claim, wherein the circulation of the spent catalyst is carried out by moving baskets, a conveyor belt, a moving grid, a worm screw, or in suspension with the leaching solution, or is simulated by permuting the injection point of the leaching solution.

5. Method according to one of the preceding claims, in which the solid / liquid separation is carried out by sedimentation, by filtration, by draining and / or by centrifugation.

6. A method according to any preceding claim, wherein the leaching steps are carried out in stirred tanks and the separation steps are carried out with filters.

7. Method according to one of the preceding claims, which is carried out with a belt filter on which the spent catalyst is conveyed on a perforated conveyor belt on which it is sprayed with the leaching solution circulating countercurrent to the spent catalyst.

8. A method according to the preceding claim, wherein the spent catalyst is supplied in suspension onto the strip by means of a device comprising at least two stirred tanks operating in a switchable mode: when the first tank feeds the strip with suspension, the suspension of the spent catalyst is prepared in the second tank with the leaching solution coming from the downstream leaching stage, then, when the first tank is empty, the suspension is fed to the strip by the second tank, and the suspension of the spent catalyst is prepared in the first tank with the leaching solution coming from the downstream leaching stage.

9. Method according to one of the preceding claims, characterized in that the organic compound of the leaching solution has complexing properties, and possibly also acids.

10. Method according to the preceding claim, characterized in that the organic compound comprises one or more chemical functions chosen from a carboxylic acid, phosphonic acid, sulfonic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide function, or else compounds including a furanic cycle or else sugars.

11. Method according to one of claims 9 or 10, characterized in that the organic compound is chosen from at least one of the following compounds: formic acid, acetic acid, oxalic acid, malonic acid, glutaric acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, γ-ketovaleric acid, succinic acid, acetoacetic acid, gluconic acid, ascorbic acid, phthalic acid, salicylic acid, maleic acid, malic acid, fumaric acid, acrylic acid, thioglycolic acid, 2-hydroxy-4-methylthiobutanoic acid, glutamic acid, N-acetylglutamic acid, alanine, glycine, cysteine, histidine, aspartic acid, N-acetylaspartic acid, 4-aminobutanoic acid, 1,2-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA),N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), bicine, tricine, l-hydroxyethylidene-l,l-diphosphonic acid (HEDP or etidronic acid), nitrilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), 4-Sulfophthalic acid, acid,

12.

13.

14.

15. 3-(N-morpholino)-2-hydroxy-l-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid. Process according to one of claims 9 or 10, characterized in that the organic compound is chosen from at least one of the following compounds: dimethylglyoxime, methyl acetoacetate, ethyl acetoacetate, ethyl lactate, methyl glycolate, ethyl glycolate, dimethyl malate, diethyl malate, dimethyl tartrate, diethyl tartrate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, methyl 3-methoxypropanoate, methyl 3-(methylthio)propanoate, ethyl 3-(methylthio)propanoate, ethylene glycol, diethylene glycol, triethylene glycol, a polyethylene glycol (with a molecular weight of between 200 and 1500 g / mol), propylene glycol, glycerol, 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, triethylene glycol dimethyl ether, crown ether, acetophenone, 2,4-pentanedione, pentanone, glucose, fructose, sucrose, sorbitol, xylitol,mannitol, y-valerolactone, propylene carbonate, octylamine, N,N-diethylformamide, N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, propanamide, l-methyl-2-pyrrolidinone, tetramethylurea, N,N'-dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5-hydroxymethylfurfural, ethyl 3-hydroxybutanoate, 2-hydroxyethyl acrylate, l-vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'-bis(2-hydroxyethyl)ethylenediamine. Method according to one of the preceding claims, characterized in that the concentration of organic compound(s) in the leaching solution is defined so that the molar ratio of organic compound / extracted metal(s), for the organic compound or for each of the organic compound(s) is between 0.2 and 25., Method according to one of the preceding claims, in which the used catalyst is subjected to at least one pretreatment step before the first leaching / separation step chosen from deoiling, regeneration, separation of contaminant / impurity type compounds, grinding or even washing with water. A method according to any preceding claim, wherein at least a portion of the extracted metal(s) solution is used. as an impregnation solution for preparing a new catalyst comprising a support based on oxide(s), said extracted metal(s) remaining in liquid phase from extraction until impregnation.

16. Method according to the preceding claim, in which the solution of extracted metal(s) is subjected to at least one treatment step before impregnation, said treatment step being chosen from a concentration, a dilution and / or a modification of the composition of the solution by addition or elimination, total or partial, of at least one compound from said solution.

17. Method according to claims 15 and 16, characterized in that at least part of the impregnation solution is reused after impregnation of said oxide-based support(s) as a supplement to the leaching solution.

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