Batch leaching method for recycling catalyst metals

Abstract

The invention relates to a batch method for leaching a spent catalyst comprising a metal from group VIB, and / or a metal from group VIII, and a support based on one or more oxides, characterised in that the method comprises N leaching steps, N being ≥ 2, by bringing the spent catalyst into contact with a leaching solution comprising an organic compound, wherein each leaching step is followed by a solid / liquid separation step, and wherein the method comprises the following successive steps i, i varying from 1 and N: i) bringing into contact: - the spent catalyst containing a metal content C(i-1) with - a leaching solution containing an extracted metal content S(N-i) to produce, after a solid / liquid separation step, - a spent catalyst containing a metal content C(i), and - the leaching solution containing an extracted metal content S(N-i+1), wherein C(i-1) > C(i) and S(N-i) < S(N-i+1).

Description

[0001] BATCH LEACHING PROCESS FOR RECYCLING CATALYST METALS

[0002] Technical field

[0003] The present invention relates to the recycling of catalyst metals, particularly from hydrocarbon hydrotreatment or hydroconversion units. More particularly, the present invention relates to a discontinuous leaching process for the recycling of catalyst metals, enabling a high metal extraction rate and reduced leaching solution consumption to be ensured.

[0004] Prior art

[0005] Most of the technological innovations needed for the energy transition (electric vehicles, wind power, fuel cells, batteries, etc.) require the massive use of metals. To meet this demand while ensuring sustainable development, metal recycling is becoming a major challenge for the coming century.

[0006] 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 considered 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.

[0007] However, processes have been developed to recover metals from catalysts, in order to recycle them for the manufacture of new catalysts.

[0008] For example, patent application US 2007 / 0167321 proposes recovering 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 form the new catalyst by impregnating a support. Patent application FR3117381 proposes the production of a recycled catalyst for hydrotreatment or hydroconversion of hydrocarbons.Cobalt and molybdenum are extracted using an aqueous solution containing at least one organic acid. The resulting solution is then used directly for impregnation onto an aluminum support to produce a recycled catalyst. The extracted metals remain in the liquid phase throughout this process.

[0009] Most processes for recovering metals operate in batch mode, providing one or more contacts between the leaching solution and the solid, without moving the solid. On an industrial scale, it is sometimes preferable to maintain a batch process given the relatively low tonnages of certain batches of catalysts.

[0010] In order to increase the metal extraction rate, it is possible to carry out several successive extractions by recontacting the depleted solid with a new metal-free leaching solution. This strategy, known to those skilled in the art, however leads to a significantly higher consumption of leaching solution compared to a single contact. It is often to be avoided because of the costs of preparing the leaching solution and the energy required to reconcentrate the solution downstream.

[0011] The present invention aims to improve the processes for recovering metals from catalysts by proposing a discontinuous (or batch) leaching process for recycling catalyst metals making it possible to ensure a high metal extraction rate as well as reduced leaching solution consumption.

[0012] Summary of the invention

[0013] The invention relates to a discontinuous process for leaching a spent catalyst comprising a metal from group VI B, and / or a metal from group VIII 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 contacting the spent catalyst with a leaching solution comprising an organic compound, each leaching step being followed by a solid / liquid separation step, the process comprising the following successive steps i, i varying from 1 and N: i) contacting:

[0014] - the spent catalyst containing a C(i-1) metal / metals content, with

[0015] - a leaching solution containing an S(Ni) content of extracted metal(s), to produce, after a solid / liquid separation step, - a spent catalyst containing a C(i) content of metal(s), and

[0016] - the leaching solution containing a content S(N-i+ 1 ) of extracted metal(s), in which C(i-1) > C(i) and S(Ni) < S(N-i+1).

[0017] 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 single-stage or multi-stage batch process using a new metal-free leaching solution for each leaching stage.

[0018] 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.

[0019] Alternatively, the number of steps N is between 2 and 8.

[0020] Alternatively, the metal / metals content in the SO leach solution is zero.

[0021] According to one variant, the method is carried out cyclically, the number of cycles is at least 2.

[0022] In this variant, a leaching solution from one cycle is used as a leaching solution in the next cycle.

[0023] According to one 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.

[0024] Alternatively, each solid / liquid separation step is carried out in the vessel in which the corresponding leaching step is carried out or in separate separation equipment.

[0025] Alternatively, the organic compound in the leaching solution has complexing properties, and possibly also acidic properties.

[0026] 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 compounds including a furanic cycle or sugars. 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, 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, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP or etidronic acid), nitrilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), acid 4-Sulfophthalic acid, 3-(N-morpholino)-2-hydroxy-1-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid.,

[0027] 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, 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, 1-methyl-2-pyrrolidinone, tetramethylurea, N,N'-dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5-hydroxymethylfurfural, ethyl 3-hydroxybutanoate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'-bis(2-hydroxyethyl)ethylenediamine.,

[0028] 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.

[0029] 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.

[0030] According to a variant, at least a portion of the extracted metal(s) 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.

[0031] 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.

[0032] According to one variant, at least part of the impregnation solution is reused after impregnation of said oxide-based support(s) as a supplement to at least one of the leaching solutions.

[0033] Definitions

[0034] For the purposes of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination.

[0035] For the purposes 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, for the purposes of the present invention, a preferred range of pressure values ​​may be combined with a preferred range of temperature values.

[0036] In the following 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 clarification will be provided by the present invention. In the present description, the term "include" 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 "include" includes the exclusive and closed term "consist".

[0037] In this description, the term "leaching" is synonymous with the term "extraction", unless otherwise indicated. The term "leaching" or "extraction" in this description means extracting one or more metals from a solid (spent catalyst) by dissolving it in a liquid (leaching solution or extraction solution).

[0038] In this description, the term "leaching step" is synonymous with the term "leaching stage", a term often used in the field of leaching.

[0039] 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.

[0040] 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 VI I IB) according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IIIPAC classification, and group VIB to the metals in column 6.

[0041] The metal content is measured by X-ray fluorescence.

[0042] List of figures

[0043] Figure 1 represents a diagram according to the method according to the invention.

[0044] Detailed description

[0045] The present invention relates to the recycling of catalyst metals originating in particular from hydrocarbon hydrotreatment or hydroconversion units.

[0046] Hydrotreatment refers to all the purification processes that eliminate, by the action of hydrogen, the various impurities contained in hydrocarbon feedstocks. Hydrotreatment processes eliminate, by the action of hydrogen, impurities present in 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 hydrodemetallization). Hydrotreatment can thus bring the hydrocarbon to the required specifications (sulfur content, aromatics, etc.) for a given application (car fuel, gasoline or diesel, domestic heating oil, etc.).Automotive standards, in particular, have imposed a very significant reduction in sulfur in diesel and gasoline fuels, with hydrotreatment thus making it possible to bring these products up to the required specifications.

[0047] 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.

[0048] It should be remembered that hydrocracking (also known as hydroconversion) of heavy hydrocarbon fractions is a key refining process that allows the production, from excess and low-value heavy feedstocks, of lighter fractions such as gasoline, jet fuels and light diesel fuels that the refiner is looking for to adapt its production to demand. Some hydrocracking processes also allow the production of a highly purified residue to be obtained, which can be used as an excellent base for oils.

[0049] The hydrocarbon feedstock targeted by hydrotreatment and / or hydroconversion can be of different types. The feedstock may be of fossil origin or derived from the conversion of biomass or waste, taken alone or in a mixture. The feedstocks that are treated, and in particular those mentioned below, generally contain heteroatoms such as sulfur, oxygen and nitrogen and, for heavy feedstocks, they most often also contain metals.

[0050] The fossil feedstock is in particular a cut from coal or hydrocarbons produced from natural gas, possibly in mixtures. It can also be heavy petroleum or synthetic cuts, for example kerosene, gas oil or distillates from atmospheric and vacuum distillation in order to produce kerosene, gas oil or vacuum distillate that 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 a preliminary step in the treatment of a feedstock by a hydroconversion / hydrocracking type process.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 from thermal or catalytic conversion processes, taken alone or in a mixture.

[0051] 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, cottonseed, peanut, linseed and crambe oils and all oils derived for example from sunflower or rapeseed by genetic modification or hybridization, this list not being exhaustive. 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 biomass conversion can also advantageously be chosen from fatty acid methyl esters of vegetable and / or animal origin or fatty acid methyl esters from used edible vegetable oils.

[0052] The feedstock from biomass conversion may also be selected from feedstocks from thermal or catalytic biomass conversion processes, such as oils that are produced from biomass, particularly lignocellulosic biomass, with various liquefaction methods, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to 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).

[0053] The feedstock from biomass conversion can also advantageously be chosen from feedstocks from the paper industry.

[0054] The feedstock from waste conversion can be pyrolysis oil from plastics, tires, or solid recovered 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). Conventional hydrotreatment catalysts generally comprise an oxide support and an active phase based on metals from groups VI, B, and VIII in their oxide forms, as well as phosphorus. The preparation of these catalysts generally includes 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.

[0055] 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".

[0056] The catalysts used in hydrocracking are bifunctional, i.e. combining an acid function with a hydrogenating function. The acid function is provided by supports with large surface areas (150 to 800 m 2 .g' 1generally) with 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

[0057] When operating in a hydrotreatment or hydrocracking process, the catalyst is deactivated by the accumulation of coke and / or sulfur compounds or compounds containing other heteroelements on the surface of the catalyst. After a certain period, its replacement is therefore necessary.

[0058] To combat these drawbacks, the regeneration (also called soft calcination) of hydrotreatment / hydrocracking catalysts is an economically and ecologically attractive process, as it allows these catalysts to be reused in industrial units rather than being landfilled or recycled (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. However, 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 reduced compared to that of a fresh catalyst.Eventually, it can be reused in less demanding applications.

[0059] 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, catalyst rejuvenation nevertheless leads in most cases to a catalyst with lower activity 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 strength), or because they contain too large a quantity of contaminants, making the performance of the regenerated or rejuvenated product insufficient.

[0060] 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.

[0061] The worn catalyst

[0062] 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 that 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 prior 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 dimensioning lower than that desired (e.g. "fines" of catalyst particles). This term also includes an at least partially spent capture mass.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] According to a particularly preferred variant, the support for the used catalyst consists of alumina, silica or silica-alumina.

[0067] 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 group FAU, BEA, ISV, IWR, IWW, MEI, UWY and more preferably, the zeolite is selected from the group FAU and BEA, such as zeolite Y and / or beta, and particularly preferably such as zeolite USY and / or beta.

[0068] 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.

[0069] 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™.

[0070] The specific surface area of ​​the oxide support is advantageously between 5 and 400 m 2 .g- 1 , preferably between 10 and 350 m 2 .g' 1 , more preferably between 40 and 350 m 2 .g' 1 . The specific surface area is determined in the present invention by the BET method according to ASTM D3663.

[0071] 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.

[0072] The Group VIII metal content 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.

[0073] The Group VIB metal content 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 MoOa and WO3 respectively.

[0074] 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 between 0.3 and 0.5.

[0075] The spent catalyst may also contain phosphorus as a dopant. A dopant is an added element that, in itself, has no catalytic properties but increases the catalytic activity of the active phase.

[0076] 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.

[0077] 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. 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] Preferably, the silicon content of the spent 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 spent catalyst.

[0082] 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 spent catalyst.

[0083] 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.

[0084] 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.

[0085] 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. According to another embodiment, the spent catalyst comprises or consists of fines and / or products outside specifications resulting from the various unit operations for manufacturing new catalysts.

[0086] Pretreatments (optional)

[0087] 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.

[0088] • Deoiling

[0089] The discharge of spent catalyst from a hydrotreating 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 oxygen-free), 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 inert gas flow rate 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 can be carried out by light hydrocarbons, by steam treatment or any other similar process.

[0090] • Regeneration

[0091] The used catalyst, possibly de-oiled, can be subjected to a coke and sulfur removal step: a regeneration step, which removes all or part of the coke, sulfur and / or chlorine possibly deposited on the catalyst.

[0092] Even if possible, 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 regeneration in said plant (ex-situ regeneration).

[0093] The regeneration step is generally carried out in a gas stream containing oxygen, usually 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.h' 1, more preferably from 30 to 1000 NL.h-1 , and particularly preferably from 40 to 500 NL.h' 1 The duration of the regeneration is preferably 2 hours or more, more 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.

[0094] 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 m 2 / g, preferably between 30 and 280 m 2 / g, preferably between 40 and 260 m2 / g, very preferably between 80 and 250 m 2 / g.

[0095] The pore volume of the regenerated catalyst is generally between 0.1 cm 3 / g and 1.3 cm 3 / g, preferably between 0.2 cm 3 / g and 1.1 cm 3 / g.

[0096] 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.

[0097] • Heat treatment under a gas flow 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. This heat treatment step under a gas stream containing hydrogen sulfide is preferably carried out before regeneration.

[0099] • Grinding

[0100] The spent catalyst, possibly deoiled, regenerated and / or subjected to H2S treatment, can 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, 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 spent 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.

[0102] • Washing with water

[0103] The used catalyst, possibly deoiled, regenerated, subjected to hLS treatment and / or crushed, can undergo a water washing step.

[0104] The volume of water used in this washing step is advantageously greater than the total pore volume of the spent catalyst. This volume may in particular be in a range from 2 to 20 times the total pore volume of the spent catalyst, preferably between 5 and 10 times said pore volume.

[0105] The washing step can be carried out at any suitable temperature, for example between 5°C and 150°C, preferably between room temperature (20°C) and 70°C. During the washing step, it is advantageous to mix the spent catalyst so as to ensure efficient washing. The washing step can be carried out in continuous or 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 such as a solid / liquid extractor or industrial mixer.

[0106] Leaching process

[0107] The spent catalyst, optionally pretreated, is subjected to the discontinuous leaching process according to the invention, characterized in that said process comprises N leaching steps, N being greater than or equal to 2, by contacting the spent catalyst with a leaching solution comprising at least one organic compound, each leaching step being followed by a solid / liquid separation step, the process comprising the following successive steps i, i varying from 1 to N: i) contacting:

[0108] - the spent catalyst containing a C(i-1) metal / metals content, with

[0109] - a leaching solution containing an S(Ni) content of extracted metal(s), to produce, after a solid / liquid separation step,

[0110] - a spent catalyst containing a C(i) metal / metals content, and

[0111] - the leaching solution containing a content S(N-i+ 1 ) of extracted metal(s), in which C(i-1) > C(i) and S(Ni) < S(N-i+1).

[0112] The process according to the invention is characterized by the fact that the spent catalyst (the most heavily loaded with metals) always first sees the leaching solution most enriched in metal / metals, preferably from the leaching / separation step N-1 of the previous cycle, in order to recover the desired solution of extracted metal / metals and a catalyst partially depleted in metal / metals. Then follow additional steps of leaching / separation of the catalyst increasingly leached of these metals with solutions less and less loaded with extracted metals until the last step (step N) using a leaching solution preferably free of metals in order to recover the catalyst depleted in metal / metals.This principle ensures a high metal concentration of the final solution and reduced leaching solution consumption compared to a single-stage or multi-stage batch process using a new metal-free leaching solution for each leaching step.

[0113] Figure 1 provides an illustration of the process according to the invention with 3 leaching / separation steps (N=3) with i steps varying from 1 to 3. Each block numbered 1, 2 and 3 represents a leaching step by bringing the solid into contact with the leaching solution, then the solid / liquid separation symbolized by a dotted line. The 3 leaching / separation steps are carried out in the same container.

[0114] The first leaching / separation step 1 is carried out by bringing the spent catalyst having a CO content of metal / metals into contact with the leaching solution most enriched in metals and having a content S2 of extracted metal / metals, preferably from the previous leaching / separation step of the previous cycle, then a solid / liquid separation is carried out in order to recover the (final) solution having a content S3 of extracted metal / metals and a catalyst partially depleted in metal / metals having a content C1.

[0115] In other words, we contact, when N=3 and i=1:

[0116] - the spent catalyst containing a metal / metal CO content, with

[0117] - a leaching solution containing an S2 content of extracted metal(s), to produce, after a solid / liquid separation step,

[0118] - a spent catalyst containing a C1 metal / metals content, and

[0119] - the (final) leaching solution containing a content S3 of extracted metal(s), in which CO > C1 and S2 < S3.

[0120] In the leaching / separation step 2, the catalyst partially depleted in metal / metals having a metal / metal content C1 is brought into contact with the solution enriched in metals and having a content S1 of extracted metal / metals, preferably from the previous leaching / separation step of the previous cycle, then a solid / liquid separation is carried out in order to recover the solution enriched in extracted metal / metals having a content S2 of extracted metal / metals and a catalyst even more depleted in metal / metals having a content C2. The solution S2, preferably stored in a stirred tank ST2, will preferably be used during the next leaching cycle according to the method according to the invention.

[0121] In other words, we contact, when N=3 and i=2:

[0122] - the spent catalyst containing a C1 metal / metals content, with

[0123] - a leaching solution containing a content S1 of extracted metal(s), to produce, after a solid / liquid separation step,

[0124] - a spent catalyst containing a C2 metal / metals content, and

[0125] - the leaching solution containing a content S2 of extracted metal(s), in which C1 > C2 and S1 < S2.

[0126] In the leaching / separation step 3, the catalyst further depleted in metal / metals and having a metal / metal content C2 is brought into contact with the leaching solution S0 , preferably free of metal / metals, then a solid / liquid separation is carried out in order to recover the solution having a content S1 of extracted metal / metals and a catalyst further depleted in metal / metals having a content C3. The solution S1 , preferably stored in a stirred tank ST1 , will preferably be used during the next leaching cycle according to the process according to the invention. Then the catalyst depleted in metal / metals C3 is discharged.

[0127] In other words, we contact, when N=3 and i=3:

[0128] - the spent catalyst containing a C2 content of metal / metals, with

[0129] - a leaching solution containing a content S0 of extracted metal(s), to produce, after a solid / liquid separation step,

[0130] - a spent catalyst containing a C3 metal / metals content, and

[0131] - the leaching solution containing a content S1 of extracted metal(s), in which C2 > C3 and SO < S1, preferably the leaching solution S0 is free of metal(s), i.e. the content of extracted metals in the solution S0 is preferably zero.

[0132] The batch process is advantageously carried out cyclically, a cycle comprising the loading of a spent catalyst into a container, the treatment of said spent catalyst by the process according to the invention, then the unloading of the catalyst depleted in metal / metals and the recovery of the different leaching solutions which are preferably stored and used during the next leaching cycle according to the process according to the invention. The number of cycles which are repeated is advantageously at least 2.

[0133] The discontinuous process according to the invention therefore advantageously follows a cyclical sequence of N leaching stages by solid-liquid contact and N liquid / solid separation stages.

[0134] The number of steps N of the method according to the invention is generally between 2 and 8, preferably between 2 and 4.

[0135] The leaching solutions used, named So to SN-I, are preferably stored in stirred tanks between each new cycle of the process according to the invention.

[0136] The SO solution corresponds to the "fresh" leaching solution, preferably free of metal / metals, which is prepared for each cycle. It can be prepared outside the container or directly in the container. As a reference, the metal / metal content in the SO leaching solution is zero.

[0137] The other solutions Si, S2, ... SN-I are advantageously prepared during the first cycle only, and are automatically regenerated during the following cycle. The SN solution corresponds to the final solution of extracted metal / metals and is therefore the desired solution, the solution most heavily loaded with metal / metals.

[0138] The various solid / liquid contact leaching steps can be carried out in a container into which the spent catalyst is loaded at the beginning of the process. The solid / liquid separation step carried out after each corresponding leaching step can be carried out in this same container or in separation equipment separate from the container. The container can be chosen from a stirred tank, a stirred tank with a filter bottom, a Nutsche filter or a fixed bed.

[0139] When the leaching step and the separation step are carried out in the same vessel, the separation can be carried out for example by percolation of the leaching solution through the cake.

[0140] When the separation step is carried out in a separation equipment separate from the container, the suspension of depleted catalyst with the metal-enriched solution after contacting is transferred to this equipment for separation, and then the filter cake of the depleted catalyst is resuspended in said container with a leaching solution.

[0141] 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 spent 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 spent catalyst.

[0142] 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.

[0143] According to a first mode of operation, the container is a stirred tank in which the stirrer ensures the suspension of the solid in the liquid for a sufficient contact time. Then the stirring is stopped and the solid settles at the bottom of the tank. The liquid is drawn off through a tapping located above the solid level.

[0144] According to a second mode of operation, the container is a Nutsche filter, known to those skilled in the art. In this case, the suspension of the solid and the liquid is ensured by repulping the cake for a sufficient time. Then the filtration is preferably carried out under pressure by engassing with air and / or nitrogen. At the end of the cycle, the blade is lowered and pushes the cake towards the outlet.

[0145] According to a third mode of operation, the container is a stirred tank with a filter bottom, in which the stirrer ensures that the solid is suspended in the liquid for a sufficient contact time. Then the liquid outlet is pushed by engassing with air and / or nitrogen towards the outlet located at the bottom of the tank. The solid is retained by a filter grid positioned at the bottom of the tank.

[0146] According to a fourth mode of operation, the container is a stirred tank, in which the stirrer ensures the suspension of the solid in the liquid for a sufficient contact time. Then the suspension is transferred to a filter press where the metal-enriched solution is separated from the cake. Each of the following leaching steps is carried out either by washing the cake remaining in the filter press with the corresponding leaching solution obtained upstream or by unblocking the filter press and redispersing the filter cake in said leaching solution, the solid and said solution being remixed in the stirred tank.

[0147] In another mode of operation, the container is a fixed bed. Contact with the liquid is achieved by circulation of the liquid provided by a pump. After a sufficient time, the recycling of the liquid at the top of the column is stopped and the column is drained, possibly blown with air. The liquid is collected and the solid is discharged from the column bed.

[0148] 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.

[0149] 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.

[0150] 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).

[0151] It has indeed been shown that adding an organic compound to the solution (usually 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 spent catalyst and any other components of the spent catalyst remain in the solid phase and are thus easily eliminated. It should be noted that the organic compounds that 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 soluble metal complex 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.

[0152] This organic compound, or at least one of them when there are several, may 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.

[0153] 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, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP or etidronic acid), nitrilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), 4-Sulfophthalic acid, 3-(N-morpholino)-2-hydroxy-1-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid.,

[0154] 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 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, — diethylformamide, N,N-dimethylformamide, N-methylformamide, N,N- dimethylacetamide, propanamide, 1-methyl-2-pyrrolidinone, tetramethylurea, N,N'- dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5- hydroxymethylfurfural, ethyl 3-hydroxybutanoate, 2-hydroxyethyl acrylate, 1- vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'- bis(2-hydroxyethyl)ethylenediamine.,

[0155] Preferably, the organic compound is selected 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 selected 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.

[0156] 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.

[0157] When multiple organic compounds are present, different molar ratios apply for each of the organic compounds present.

[0158] The concentration of organic compound in the leaching solution is generally between 5 and 300 g / L, preferably between 15 and 200 g / L.

[0159] 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, in particular nitric acid, sulfuric acid or boric acid. 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.

[0160] In general, 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 in 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.

[0161] Contact is carried out with the extraction solution under the following conditions:

[0162] 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.

[0163] The pressure is generally between atmospheric pressure and 20 bars (2 Mpa), particularly between atmospheric pressure and 10 bars (1 Mpa).

[0164] The contact time per leaching step is generally between 1 minute and 20 hours, preferably between 5 and 300 minutes, and most preferably between 5 and 120 minutes.

[0165] 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 may therefore be at room temperature, or have been heated, for this specific contacting step. It may 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.

[0166] The amount 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 (S0) per mass of spent catalyst to be treated (C0), is between 1 and 15, preferably between 2 and 12, more preferably between 3 and 10. According to one embodiment, when the spent catalyst contains only one metal from group VI B or one metal from group VIII respectively, a fortiori only one metal from group VI B 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 VI B and at least one metal from group VIII, and either only the metal from group VI B or from group VIII respectively, or both the metal from group VI B and the metal from group VIII is extracted.

[0167] At the end of the process according to the invention, on the one hand, a leached catalyst depleted in metal / metals is obtained, and on the other hand, the leaching solution enriched in at least one metal from group VI B and / or at least one metal from group VIII.

[0168] 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.

[0169] The total 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 extracted metal / metals in the final solution relative to the mass of metal / metals initially present on the spent catalyst.

[0170] Valorization of the leaching solution

[0171] 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.

[0172] 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 “direct” recovery, 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).

[0173] Before its use as an impregnation solution, the extracted metal(s) solution 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 liquid phase during these treatments.

[0174] • Purification

[0175] The extracted metal / metal solution may be subjected to a purification step. The purpose of purification is to remove all or part of the impurities possibly contained in the metal solution, in particular impurities potentially present on the used catalyst or linked to a partial dissolution of the support of said catalyst. Purification may take place in a single step or in several successive steps.

[0176] In the event that the extracted metal(s) solution contains suspended solids after the final liquid / solid separation step, any known method for removing these suspended materials may be used. Preferably, this removal is carried out by filtration (e.g., microfiltration and ultrafiltration on a cross-flow filter). Other methods are centrifugation, coagulation or sedimentation.

[0177] For dissolved impurities, such as arsenates or arsenites, all known methods may be used, including, and preferably, sorption on solids, precipitation and solvent extraction, taking care not to remove at the same time the metals of interest which have been extracted.

[0178] • Concentration

[0179] 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 possibly 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 an 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, whether or not containing the organic compound, extracted from the metal solution may be recycled in the process according to the invention as a leaching solution.

[0180] 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.

[0181] 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.

[0182] When one wants to remove solvent and organic compound(s) when they are used, a preferred technique is evapoconcentration.

[0183] • Adjustment of the composition of the metal solution

[0184] The extracted metal(s) solution, 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 metal extraction 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.

[0185] 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 VI B 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.

[0186] As an example for 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 (H3PM012O40), and their salts, and possibly silicomolybdic acid (H4SiMoi2C>4o) and its salts. The sources of molybdenum can also be any heteropolycompound of the Keggin, lacunar Keggin, substituted Keggin, Dawson, Anderson, Strandberg type, for example. Molybdenum trioxide and heteropolycompounds of the Keggin, lacunar Keggin, substituted Keggin and Strandberg type are preferably used.

[0187] The tungsten precursors that can be used are also well known to those skilled in the art. For example, among the tungsten sources, 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 possibly silicotungstic acid (H4SiWi204o) and its salts. The tungsten sources can also be any heteropolycompound of the Keggin, vacated Keggin, substituted Keggin, or 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.

[0188] 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.

[0189] Nickel precursors that can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. It can also be nickel acetoacetate.

[0190] 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.

[0191] The preferred phosphorus precursor is phosphoric acid H3PO4, but its esters and salts such as ammonium phosphates are also suitable, as are polyphosphates. Phosphorus can also be introduced together with the group VIB element(s) in the form of Keggin, vacated Keggin, substituted Keggin, or Strandberg-type heteropolyanions.

[0192] The 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 the catalysts. Thus, one or more organic additives well known to those skilled in the art can be advantageously added at this stage. Generally, the amount of each organic additive added is defined so that the additive / metal molar ratio is between 0.1 and 1 in the impregnation solution.

[0193] 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.

[0194] The extracted metal / metal solution may contain an excess of organic compounds compared to the desired impregnation solution. The ratios between organic compounds and metals can be adjusted in two ways. The first way is to add a concentrated solution of metal precursors, or to dissolve these metal precursors directly to achieve the desired ratios. In this case, the final catalyst obtained will contain a mixture of recycled and new metals.

[0195] 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, liquid-liquid extraction, adsorption or membrane separation.

[0196] 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. To do this, an oxide support, or a catalyst already containing one or more metals, is brought into contact with the extracted metal / metal solution. Contacting can be done by any known method, such as ion exchange, dry impregnation, excess impregnation, vapor deposition, etc. Contacting can take place in one step or in several successive steps.

[0197] 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.

[0198] A catalyst already containing one or more metals can also be brought into contact with the solution of extracted metal(s). This can be a catalyst that has been depleted of metals, and in particular be a spent catalyst itself, possibly regenerated and then optionally rejuvenated.

[0199] 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 catalyst in a volume of solution (often largely) greater than the pore volume of the support or catalyst. Dry impregnation consists of introducing a volume of impregnation solution equal to or slightly less than the pore volume of the support or catalyst. Dry impregnation makes it possible to deposit all of the constituents of the impregnation solution on a given support or catalyst. 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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 traversed bed.

[0204] According to one 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.

[0205] Optionally, the drying can 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.

[0206] Preferably, the catalyst is not subjected to calcination. 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 optionally calcination.

[0207] 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, more 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.

[0208] 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.

[0209] 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 non-additive catalysts, before the final optional sulfurization, it being understood that, preferably, no calcination step is carried out after its introduction.

[0210] Before use, the new catalyst can undergo an optional sulfurization step. 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, M0S2 and CogSs. Sulfurization is carried out by injecting the catalyst with 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 (DM DS) are H2S precursors commonly used to sulfurize catalysts. 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.

[0211] Examples

[0212] 1: Discontinuous leaching process

[0213] Example 1 illustrates the process according to the invention in 3 leaching / separation stages (N=3). 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 micrometers (pm) and containing 21% by weight of molybdenum (expressed as MoOa 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.

[0214] The extraction device is a Nutsche filter.

[0215] Three stirred leach solution storage tanks are used to store leach solutions SO, S1, and S2. Solution S0 is the “fresh” metal-free leach solution that is prepared for each cycle. The other solutions S1 and S2 are prepared for the first cycle only and are automatically replenished during the cycle.

[0216] The steps to follow in order are:

[0217] Preparation of a spent catalyst / leach solution suspension by loading the ground solid C0 into a stirred tank containing S2, which was generated during the previous cycle, and loading the suspension into a Nutsche filter. The stirrer ensures suspension of the solid for 30 min after the catalyst loading is complete.

[0218] The suspension is stirred for a further 210 minutes, then pressure filtration is carried out at 3 bars (0.3 MPa). The recovered filtrate corresponds to the final solution of the S3 process, which can be used directly, or possibly after concentration, for impregnation. The C1 cake remains in the Nutsche filter.

[0219] The entire tank containing solution S1 is loaded into the Nutsche filter and is brought into contact with cake C1 by repulping for 10 min. Subsequently, filtration is carried out under pressure at 3 bars (0.3 MPa). The recovered filtrate is sent to the tank which will be used during the next cycle as leaching solution S2. Cake C2 remains in the Nutsche filter.

[0220] The “fresh” leaching solution free of metals S0 is loaded into the Nutsche filter and is brought into contact with the cake by repulping C2 for 10 min. Subsequently, filtration is carried out under pressure at 3 bars (0.3 MPa). The recovered filtrate is sent to the tank which will be used during the next cycle as leaching solution S1.

[0221] The Nutsche filter blade is set in the lower position and pushes the cake towards the outlet. The cake is stored in drums. In addition, the S0 solution is prepared by mixing water and glutaric acid at room temperature in a stirred tank. Example 2: Comparative examples

[0222] In this example, the process according to the invention as described in Example 1 is compared to a discontinuous process with a single extraction, where the solid and the extraction solution are brought into contact followed by a liquid / solid separation. The comparison is also carried out with a process comprising 3 successive extractions, i.e. according to the following operations:

[0223] • Step 1: Bringing the new solid into contact with the new leaching solution (free of metals) then separating the liquid / solid, using a liquid / solid ratio of 3 kg / kg. The separated liquid is sent to the final solution.

[0224] • Step 2: Bringing the depleted solid from step 1 into contact with the new leaching solution, at a liquid / solid ratio of 3 kg / kg. The separated liquid is added to the final solution.

[0225] • Step 3: Bringing the depleted solid from step 2 into contact with the new leaching solution, at a liquid / solid ratio of 3 kg / kg. The separated liquid is added to the final solution.

[0226] Performance is measured in terms of molybdenum extraction rate and leach solution consumption. The extraction rate is the mass of molybdenum extracted into the final solution relative to the mass of molybdenum initially present on the catalyst. Leach solution consumption is expressed in liters of solution required per kg of molybdenum extracted.

[0227] The process performances are gathered in Table 1.

[0228] Table 1: Comparison of processes

[0229] Compared to the single-step extraction process, the process according to the invention ensures a significantly higher extraction rate.

[0230] Compared to a process of successive extractions with a fresh solution, the process according to the invention ensures a significantly reduced consumption of leaching solution, achieving a high extraction rate.

Claims

Claims 1. Discontinuous process for leaching a spent catalyst comprising at least one metal from group VI B, 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 contacting the spent catalyst with a leaching solution comprising at least one organic compound, each leaching step being followed by a solid / liquid separation step, the process comprising the following successive steps i, i varying from 1 to N: i) contacting: - the spent catalyst containing a C(i-1) metal / metals content, with - a leaching solution containing an S(Ni) content of extracted metal(s), to produce, after a solid / liquid separation step, - a spent catalyst containing a C(i) metal / metals content, and - the leaching solution containing a content S(N-i+ 1 ) of extracted metal(s), in which C(i-1) > C(i) and S(Ni) < S(N-i+1).

2. Method according to claim 1, in which the number of steps N is between 2 and 8.

3. Method according to one of the preceding claims, wherein the metal / metals content in the leaching solution S0 is zero.

4. Method according to one of the preceding claims, which is carried out cyclically, the number of cycles is at least 2.

5. Method according to the preceding claim, in which a leaching solution from one cycle is used as a leaching solution in the following cycle.

6. Method according to one of the preceding claims, in which the leaching solution / spent catalyst ratio, expressed in mass of leaching solution per mass of spent catalyst to be treated, is between 1 and 15.

7. Method according to one of the preceding claims, in which each solid / liquid separation step is carried out in a container in which the corresponding leaching step is carried out or in separate separation equipment.

8. 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.

9. 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.

10. Method according to one of claims 8 or 9, 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, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP or etidronic acid), nitrilotris(methylenephosphonic acid), diethylenetriaminepentakis(methylenephosphonic acid), 4-Sulfophthalic acid, 3-(N-morpholino)-2-hydroxy-1-propanesulfonic acid (MOPSO), 2-(4-Pyridinyl)ethanesulfonic acid, phenol-4-sulfonic acid, thiodiacetic acid and diglycolic acid.

11. Method according to one of claims 8 or 9, 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, 1-methyl-2-pyrrolidinone, tetramethylurea, N,N'- dimethylurea, acetonitrile, lactamide, furfurol, 2-furaldehyde, 5-hydroxymethylfurfural, ethyl 3-hydroxybutanoate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, N,N,N',N'-tetramethyltartramide, 3-hydroxypropionitrile and N,N'- bis(2-hydroxyethyl)ethylenediamine.

12. 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.

13. 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.

14. Method according to one of the preceding claims, in which at least a part of the solution of extracted metal(s) 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.

15. 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.

16. Method according to claims 14 and 15, characterized in that at least part of the impregnation solution is reused after impregnation of said oxide-based support(s) as a supplement to at least one of the leaching solutions.

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