Process for producing a catalyst comprising at least one group viiib metal and an oxide-based support

Abstract

The present invention relates to a process for producing a recycled catalyst comprising at least one group VIII metal M1 and comprising no group VIB metal and an oxide-based support, said process comprising at least one step of removing at least some of the carbon present on the source catalyst by washing and / or heat treatment at a temperature of less than 300°C, using an extraction solution to extract the metal M1 from said catalyst resulting from the step of removing at least some of the carbon, to give a solution of extracted metal(s), and at least one step of impregnating a support with at least one impregnation solution derived from said solution of extracted metal(s), to give an impregnated support, said extracted metal(s) remaining in the liquid phase from the extraction until impregnation.

Description

[0001] Process for producing a catalyst comprising at least one metal from group VI II B and a support based on oxide(s)

[0002] TECHNICAL FIELD

[0003] The present invention relates to the production of catalysts comprising at least one metal from group VI II B, and a support based on metal oxides. These catalysts are intended, in particular, for use in Fischer-Tropsch synthesis units.

[0004] PREVIOUS TECHNIQUE

[0005] Fischer-Tropsch synthesis processes allow the production of a wide range of hydrocarbon fractions from the CO + H2 mixture, commonly known as synthesis gas. The overall equation for Fischer-Tropsch synthesis can be written as follows: n CO + p(n+1) H2 -> CnH2n+2 + n H2O

[0006] Fischer-Tropsch synthesis is at the heart of processes for converting natural gas, coal, or biomass into fuels or intermediates for the chemical industry. These processes are called GTL (Gas to Liquids) when natural gas is used as the initial feedstock, CTL (Coal to Liquids) for coal, and BTL (Biomass to Liquids) for biomass. In each of these cases, the initial feedstock is first gasified into a synthesis gas, which comprises a mixture of carbon monoxide and hydrogen. The synthesis gas is then primarily converted into paraffins using Fischer-Tropsch synthesis, and these paraffins can then be transformed into fuels by a hydroisomerization-hydrocracking process. Recently, the term e.Fuels emerged and concerns the production of liquid fuels by Fischer-Tropsch synthesis from hydrogen produced by water electrolysis and CO produced by the reverse water-gas shift reaction between CO2 and the same hydrogen. The associated process can be called PTL (Power To Liquid) according to Anglo-Saxon terminology. The Fischer-Tropsch synthesis reaction can be carried out in different types of reactors (fixed bed, moving bed, or three-phase (gas, liquid, solid) for example, such as a perfectly stirred autoclave or bubble column), and the reaction products are notably characterized by being free of sulfur, nitrogen, or aromatic compounds.In a slurry bubble column reactor (or simply slurry), which uses a catalyst in a fine powder form, typically on the order of tens of micrometers, this powder forms a suspension with the reaction medium. The Fischer-Tropsch reaction proceeds conventionally between 1 and 4 MPa (10 and 40 bar), at temperatures traditionally ranging from 200°C to 350°C. The reaction is generally exothermic, which necessitates careful attention to the catalyst's implementation. The catalysts used for the Fischer-Tropsch synthesis are primarily cobalt- or iron-based, although other metals can be used. However, cobalt and iron offer a good performance / cost compromise compared to other metals.

[0007] Conventional Fischer-Tropsch catalysts typically comprise an oxide support and an active phase based on reduced Group VIII metals, with the possible addition of dopants to, for example, enhance activity, facilitate cobalt reduction, limit deactivation, or improve long-chain selectivity. The preparation of these catalysts generally involves impregnating the support with the metals, followed by drying and calcination to obtain the metal in its oxide form. Before use in the Fischer-Tropsch reaction, the catalyst in its oxide form is reduced in the presence of a reducing agent, which may be hydrogen.

[0008] The use of a post-impregnation additive after the addition of cobalt, such as an organic acid, to a catalyst precursor obtained by dry impregnation with a cobalt salt followed by drying, has sometimes been described as improving activity. In this case, catalysts with a smaller cobalt particle size and higher methane selectivity have been reported. (Catalysis Today, 228 (2014) 206-211 Lei Shi et al).

[0009] The catalysts used for the Fischer-Tropsch synthesis reaction are monofunctional, meaning that the support does not play a catalytic role per se and should preferably be inert if the target products are long hydrocarbon chains. Metallic cobalt is active in activating carbon monoxide and hydrogen and in promoting chain growth via the Schultz-Flory mechanism. The support is generally an oxide such as alumina, silica, silica-alumina, silica-alumina, or titanium.

[0010] During Fischer-Tropsch synthesis, the catalyst deactivates through various processes, such as coke accumulation, sintering, the formation of mixed oxide species between the support and cobalt, poisoning by sulfur or nitrogen compounds, or carburization. Therefore, after a certain period, its replacement with fresh catalyst is necessary. In a slurry process, catalyst can be withdrawn as needed, and fresh catalyst can be added at regular intervals to at least partially compensate for catalyst deactivation. The discharged catalyst can then be discarded or, if necessary, regenerated.

[0011] The discharged Fischer-Tropsch catalyst contains, within its porosity (and is embedded in it), wax (long hydrocarbon chains, solid at room temperature) produced by the reaction. Therefore, a first step of wax extraction by washing with a solvent and / or by a heat treatment to remove the waxes is preferable before carrying out the actual regeneration of the Fischer-Tropsch catalysts. This process is economically and environmentally advantageous because it allows these catalysts to be reused in industrial units rather than being sent to landfills or recycled, most often through energy-intensive metallurgical processes whose objective is metal recovery.

[0012] Patent application US2010 / 0304955, for example, describes a process for regenerating a spent Fischer-Tropsch catalyst. This process includes a dewaxing treatment to remove the wax from the catalyst before subjecting it to an oxidizing treatment at a pressure between 4 and 30 bar, followed by a reduction process to obtain a regenerated catalyst. The dewaxing treatment can consist of hydrogenolysis, solvent washing, or a combination of both. After this treatment, the catalyst still contains between 5 and 20% residual carbon, which must be removed. This is removed by oxidation at temperature, and then the catalyst undergoes a reduction process to produce a reduced catalyst. However, with repeated regenerations, catalytic performance can no longer be recovered, and it may be more economical to use fresh catalyst and dispose of the spent one.

[0013] In general, the cobalt contained in Fischer-Tropsch catalysts is not currently recycled industrially for the manufacture of new catalysts. This is despite the relatively high purity of the spent catalyst, unlike conventional hydrotreating catalysts which can contain significant quantities of metallic pollutants such as arsenic and vanadium.

[0014] Processes have also been developed to recover metals from catalysts for recycling in the manufacture of new catalysts. For example, the process described in US patent 8986632 proposes recovering cobalt, ruthenium, and aluminum after removing heavy hydrocarbons from the spent Fischer-Tropsch catalyst by calcination. The hydrocarbon-free catalyst is reacted with hydrogen and then undergoes alkaline fusion to obtain residues. These residues are then subjected to acid leaching, followed by cobalt precipitation in the presence of oxalic acid or ammonium oxalate. Next, the cobalt oxalate is reduced, and the metallic cobalt is dissolved in nitric acid to obtain crystallized cobalt nitrate hexahydrate after evaporation of the solution.Ruthenium and aluminum are recovered separately through treatments performed on the acid leaching effluent. Yields are at least 97% for cobalt, 95% for ruthenium, and 92% for aluminum. The crystallized metal salts must then be resuspended or used as molten salts before being used to prepare new catalysts.

[0015] US patent 7754635 proposes subjecting the spent Fischer-Tropsch catalyst to a dewaxing step, followed by hydrometallurgical leaching or extraction to separate the catalyst metal(s) from the catalyst support and then recover the separated metal(s). The dewaxing step is carried out in the presence of a supercritical or near-supercritical fluid to properly extract the wax from the spent catalyst without promoting the formation of a spinel between the metal(s) and the support (which occurs if the wax removal treatment is performed at too high a temperature). The formation of this spinel is observed, for example, in patent application WO02 / 18663, in which the dewaxing step is carried out by a combination of high-temperature calcinations (600-1400°C) in the presence of air.The use of these oxidizing treatments leads to the formation of a spinel between the metal(s) and the substrate, making them resistant to leaching processes. Conversely, the use of a dewaxing treatment with a supercritical or near-supercritical fluid (C3-C12 hydrocarbon, alcohol, or water) allows the carbon content to be reduced below 1% (the maximum target level), without promoting spinel formation. A series of hydrometallurgical treatments allows for the selective dissolution of the catalyst components, which are then recovered in crystalline form by precipitation.

[0016] US patent application 2004 / 0219082 proposes a selective extraction of the different metals (cobalt and platinum) present in a Fischer-Tropsch catalyst through a series of steps that allow the metals to be recovered in ionic form: calcination of the wax present on the spent catalyst, treatment with hot sodium hydroxide to dissolve the aluminum support without solubilizing the cobalt or platinum. The solid residue containing the platinum and cobalt is then treated with a nitric acid solution to form cobalt nitrate, and the platinum present in the solid residue can then be recovered by acid leaching to form chloroplatinic acid. This method allows the recovery of metals in a pure form for reuse in other applications.

[0017] These processes are technically interesting, but they are not without drawbacks. They require a large number of complex operations to extract the metals of interest from spent catalysts for reuse in new catalysts, making them difficult to implement and therefore not very cost-effective. Scaling them up to an industrial level is thus highly unlikely.

[0018] An improved process was proposed in patent application WO22128491 A1 (IFPEN). This process describes the preparation of a recycled catalyst comprising at least one metal from Group VIB and / or at least one metal from Group VIII, and an oxide-based support. The process includes recycling at least a portion of the metal(s) from a source catalyst containing one or more metals in common with the recycled catalyst to be prepared. This involves extracting the metal(s) from said source catalyst using an extraction solution to obtain a solution of the extracted metal(s), followed by impregnation of the support with an impregnation solution derived from said extracted metal(s) solution to obtain an impregnated substrate. The advantage of the described process lies in the fact that the extracted metal(s) remain in the liquid phase from extraction until impregnation.However, the potential advantages and disadvantages associated with prior treatment of washing, decoking and / or grinding of the catalyst before metal extraction are not described or quantified.

[0019] Patent application EP4245870 A1 describes the recycling of one or more metals belonging to columns 8 to 12, present at least partially as metal sulfides in a porous material A that comprises at least one mineral oxide and has a sulfur content of at least 2%. The process describes the following successive steps: heat treatment of material A at a temperature between 350 and 900°C, washing of the treated material with an aqueous solvent, and finally, extraction of the metal(s) by contact with a solution containing a carboxylic acid. The extracted metal(s) are then deposited onto a material B, different from material A, by contact with the extraction solution. The advantage of the invention is that it allows the recycling of metals present in highly contaminated porous materials (traps, adsorbents).

[0020] The aim of the invention is to propose new processes for recycling metals contained in spent catalysts to produce new catalysts, specifically within the framework of the Fischer-Tropsch application. This involves developing improved processes that are simpler to implement on an industrial scale, while still enabling a high metal recovery rate and guaranteeing high performance (activity, selectivity, lifespan) of the catalysts prepared from the recovered metals.

[0021] SUMMARY OF THE INVENTION The invention relates firstly to a process for producing a recycled catalyst comprising at least one metal M1 from group VIII and not comprising any metal from group VI B, and optionally another metal selected from the metals of group VIII (preferably platinum), and / or boron, and a support based on oxide(s), characterized in that said process comprises the recycling of at least a portion of the metal(s) from a source catalyst comprising a metal common to the recycled catalyst to be produced, the process comprising at least:

[0022] - a step for removing at least part of the carbon present on the source catalyst, comprising at least one step of washing the source catalyst with an organic solvent, and / or at least one step of heat treating the source catalyst at a temperature below 300°C in the presence of a gas containing air, without a step of heat treating the catalyst in the presence of a gas chosen from oxygen and hydrogen, at a temperature above 300°C prior to the extraction step,

[0023] - Then, an extraction by an extraction solution of metal M1 and possibly of another metal chosen from the metals of group VIII and preferably platinum and / or boron of said catalyst from the step of removing at least part of the carbon, to obtain a solution of extracted metal(s),

[0024] - then at least one step of impregnating a support with at least one impregnation solution derived from said solution of extracted metal(s), to obtain an impregnated support, said extracted metal(s) remaining in liquid phase from extraction until impregnation,

[0025] - and a drying stage and a calcination stage of the impregnated support.

[0026] Preferably, the catalyst contains, after step a) of washing, a carbon content greater than 1% and less than 15%, expressed as a percentage by weight in relation to the total mass of said dry catalyst.

[0027] Preferably the source catalyst used in the process according to the invention does not contain more than 2% sulfur and preferably not more than 1% and very preferably not more than 0.1% and even more preferably not more than 0.01%.

[0028] Definitions

[0029] In accordance with the present invention, the various embodiments presented can be used alone or in combination with one another, without any limitation on the combinations. In accordance with the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in accordance with the present invention, a preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0030] In the following text, chemical element groups 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 according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification, and group VI B to the metals in column 6.

[0031] In the following text, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included within the described range of values. If this were not the case and the limit values ​​were not included within the described range, this clarification will be provided by the present invention.

[0032] In this description, the expression "greater than..." is understood as strictly greater, and symbolized by the sign ">", and the expression "less than" as strictly less, and symbolized by the sign "<".

[0033] According to the present invention, "extraction" is understood to mean that there is an extraction step, but that the extraction can be carried out by a single extraction operation or divided into a plurality of successive extraction operations.

[0034] According to the present invention, "impregnation" is understood to mean that there is an impregnation step, but that the impregnation can be achieved by one or a plurality of successive impregnation operations.

[0035] According to the present invention, the term "source catalyst" refers to a spent catalyst, that is, one that has already been used in production, particularly in Fischer-Tropsch synthesis plants. This catalyst may have been regenerated or rejuvenated several times prior to its use in the process according to the invention, but it will be considered a source catalyst only in its spent, untreated form after discharge from the Fischer-Tropsch unit. It may therefore, for example, contain reaction products (waxes, oils) as well as coke.

[0036] According to the present invention, the term "washed" catalyst means the "source" catalyst treated by washing in order to extract all or part of the reaction products (waxes, oils) as well as a fraction of the coke.According to the present invention, the term "support" (which will be impregnated with the impregnation solution from the extracted metal / metal solution) includes a "new" support made of oxides, but also a support that has already been impregnated with another impregnation solution - this is referred to as a pre-impregnated support - or a support that is in fact a catalyst (a support containing one or more metals) but which contains an insufficient quantity of metals, such as a used or regenerated catalyst, and also a so-called stabilized support, which has been obtained by dry impregnation of a metal onto the support, followed by a calcination step or heat treatment carried out at high temperature to form a spinel or a solid solution between the metal and the alumina of the support.

[0037] The support can also, in the sense of the invention, be a metal-depleted catalyst from the catalyst extraction step from the step of removing at least part of the carbon according to the recycled catalyst production process of the invention.

[0038] The invention thus proposes a new process in which the metal from the source catalyst is dissolved and remains in solution until it is reused as a top-up for the impregnation solution to produce the fresh / new catalyst. Unlike many prior techniques, the invention does not seek to recover the metal from the source catalyst in solid, crystalline, and monometallic form, thereby avoiding numerous precipitation / filtration operations. Unlike cases described in the literature, the extraction is carried out without requiring complete regeneration of the source catalyst; that is, the step of removing at least some of the carbon present on the source catalyst is partial, resulting in a carbon content exceeding 1% in the catalyst before the extraction step.

[0039] One advantage of the present invention is that the process is easier and less expensive to implement on an industrial scale.

[0040] Unlike the prior art, the process for producing a recycled catalyst according to the invention includes at least one step of treating the source catalyst, called the step of removing at least a portion of the carbon, prior to liquid extraction, chosen from at least one of the following treatments:

[0041] - a washing step of the source catalyst with an organic solvent allowing the extraction of the majority of the wax present around and in the porosity of the catalyst in the presence of a hot hydrocarbon solvent,

[0042] - and / or at least one heat treatment step of the source catalyst at a temperature below 300°C in the presence of an air-containing gas, allowing decoking by mild heat treatment (in the presence of oxygen-depleted air, low temperature, slow ramps). The controlled heat treatment, carried out under mild conditions, will facilitate metal extraction.

[0043] An advantage of the present invention lies in the fact that these preliminary treatments are intended to make extraction more efficient through physical or chemical processes. Removing at least some of the carbon present in the form of waxes and / or coke from the source catalyst improves contact between the extraction solution and the metals to be extracted contained in the source catalyst.

[0044] As mentioned above, the process according to the invention is preferably aimed at producing a Fischer-Tropsch catalyst.

[0045] The spent catalyst used in the recycling process according to the invention may have undergone cycles of regeneration and / or rejuvenation, but when the liquid metal extraction process is applied to it in the process according to the invention, it will be worn out.

[0046] The group VIII metal of the catalyst to be produced is preferably cobalt. Its support is preferably aluminum oxide-based, and possibly aluminum and silicon oxide-based. The source catalyst is preferably of the same type and contains at least the same group VIII metal as the catalyst to be produced.

[0047] The support can advantageously be "stabilized" by a metal, preferably from group VIII. A "stabilized" support is understood to be a support containing at least part of the metal and having undergone a calcination step at a temperature above 700°C, the group VIII metal used to prepare the so-called "stabilized" support being able to be introduced during the preparation of the support or by an impregnation step of said metal after the preparation of said support.

[0048] The invention also relates to the catalyst produced according to the process described above, which may therefore comprise entirely recycled metal(s), or partly recycled metal(s) and metals supplied by a "fresh" solution containing the metal precursor. The invention also relates to a so-called stabilized support comprising recycled metal(s), or partly recycled metal(s) and "fresh" metals, and the catalyst prepared on this support. LIST OF FIGURES

[0049] Figure 1

[0050] Figure 1 shows the block diagram of a first variant of the installation implementing the process according to the invention. In this variant, the recycled metal solution from the extraction is impregnated onto a support without any further steps being added between extraction and impregnation, nor is any source of fresh metal being used, producing a catalyst according to the invention.

[0051] Figure 2

[0052] Figure 2 shows the block diagram of a second variant of the installation implementing the process according to the invention. In this variant, the extracted metal solution is purified and concentrated prior to impregnation. The substrate is then impregnated with the recycled metal solution, using the extracted metal solution and, if necessary, the addition of more metal to this same solution.

[0053] Figure 3

[0054] Figure 3 shows a block diagram of a third variant of the installation implementing the process according to the invention. In this variant, the metal-depleted catalyst is reused after a single heat treatment without further impregnation to be impregnated with a recycled metal solution. This solution is obtained from the extracted metal solution and may include the addition of more metal to this same solution, producing a catalyst according to the invention. The extracted metal solution is purified and concentrated prior to impregnation.

[0055] Figure 4

[0056] Figure 4 shows a block diagram of a fourth variant of the installation implementing the process according to the invention. In this variant, the metal-depleted catalyst is reused and impregnated with a fresh metal solution, producing a modified support. This support is then impregnated with a recycled metal solution using the extracted metal solution and, optionally, the addition of more metal to this same solution, producing a catalyst according to the invention. The extracted metal solution is purified and concentrated prior to impregnation. The figures are highly schematic and do not necessarily represent all the operations that may be involved in the process according to the invention. Identical reference numerals from one figure to another refer to the same operation / component / device.

[0057] DESCRIPTION OF THE FIGURES

[0058] In Figure 1, step W of catalyst processing leads to the production of a spent catalyst stream, source 1. This stream is treated in washing step A1 to generate a washed catalyst stream 2, which is then treated in heat treatment step A2 at a temperature below 300°C to generate a catalyst 3 from which at least some of the coke and wax have been removed. The catalyst 3 is then contacted with an extraction solvent 4 in step B to produce, on the one hand, a metal-depleted catalyst 5 and, on the other hand, a metal solution containing the metal to be recycled 6. The metal solution 6 is then impregnated onto a support 7 (step F) to produce an impregnated support 8, which is finally dried and calcined in step G to obtain a catalyst 9 according to the invention.

[0059] In Figure 2, step W of catalyst implementation leads to the production of a spent catalyst stream, source 1. This is processed in washing step A1 to generate a washed catalyst stream 2, which is then treated in heat treatment step A2 at a temperature below 300°C to generate a catalyst 3 from which at least some of the coke and wax have been removed. Catalyst 3 is then contacted with an extraction solvent 4 in step B to produce, on the one hand, a metal-depleted catalyst 5 and, on the other hand, a metal solution containing the metal to be recycled 10.This solution then undergoes a purification step C leading to a solution 11 which is then concentrated during step D to lead to a metal solution 12, the latter undergoing a further concentration adjustment via the addition of one or more metal precursor(s) 13 to obtain, at the end of step E, a solution of metal to be recycled 6 whose concentration is satisfactory to then be impregnated onto a support 7 (step F) to lead to an impregnated support 8 which is finally dried and calcined in step G so that a catalyst 9 is obtained according to the invention.

[0060] In Figure 3, step W of catalyst implementation leads to the production of a spent catalyst stream (source 1). This is processed in washing step A1 to generate a washed catalyst stream (2), which is then treated in heat treatment step A2 at a temperature below 300°C to generate a catalyst (3) from which at least some of the coke and wax have been removed. Catalyst 3 is then contacted with an extraction solvent (4) in step B to produce, on the one hand, a metal-depleted catalyst (5) and, on the other hand, a metal solution containing the metal to be recycled (10).This solution then undergoes a purification step C, resulting in a solution 11, which is then concentrated in step D to produce a metal solution 12. This metal solution is further adjusted in concentration by adding one or more metal precursor(s) 13 to obtain, at the end of step E, a solution of the metal to be recycled 6 with a satisfactory concentration. This solution is then impregnated onto a support 7 (step F) to produce an impregnated support 8, which is finally dried and calcined in step G to obtain a catalyst 9 according to the invention. Furthermore, the metal-depleted catalyst 5 is then heat-treated in step I to obtain the catalyst support 7 used above.

[0061] In Figure 4, step W of catalyst implementation leads to the production of a spent catalyst stream (source 1). This is processed in washing step A1 to generate a washed catalyst stream (2), which is then treated in heat treatment step A2 at a temperature below 300°C to generate a catalyst (3) from which at least some of the coke and wax have been removed. Catalyst 3 is then contacted with an extraction solvent (4) in step B to produce, on the one hand, a metal-depleted catalyst (5) and, on the other hand, a metal solution containing the metal to be recycled (10).This solution then undergoes a purification step C, resulting in a solution 11, which is then concentrated in step D to produce a metal solution 12. The concentration of this metal solution is further adjusted by adding one or more metal precursor(s) 13 to obtain, at the end of step E, a solution of the metal to be recycled 6 with a satisfactory concentration. This solution is then impregnated onto a support 7 (step F) to produce an impregnated support 8, which is finally dried and calcined in step G to obtain a catalyst 9 according to the invention. Furthermore, the metal-depleted catalyst 5 is then heat-treated in step I to obtain a catalyst support 14, which is in turn impregnated in step J with a metal solution 17, itself prepared in step J' by dissolving one or more metal precursor(s) 18 in a solvent 16.The modified support 15 thus obtained at the end of step J is then calcined during step K to produce the support 7 used above.

[0062] DESCRIPTION OF IMPLEMENTATION METHODS

[0063] The source catalyst of the process according to the invention is a catalyst comprising at least one oxide support and at least one metal from Group VIII, but not comprising any metal from Group VIB, and optionally at least one other metal selected from the metals of Group VIII, preferably platinum and / or boron. The term "source" according to the invention has been defined above.

[0064] The source catalyst comprises at least one metal Ml belonging to Group VIII, and optionally at least one other metal chosen from among the Group VIII metals, preferably platinum, an oxide support, and optionally dopants. It comprises carbon in the form of coke and / or long hydrocarbon chains as described below.

[0065] The active phase of the source catalyst preferably comprises at least one metal Ml from group VIII and preferably consists of a metal from group VIII. The group VIII metal present in the active phase of the catalyst is preferably cobalt.

[0066] In a preferred embodiment, the source catalyst and the recycled catalyst to be produced may contain other doping elements, preferably selected from alkali metals, group VII metals, group I metals, group IV metals, phosphorus, and boron. Group I metals are preferably selected from silver and gold, group VII metals from rhenium and manganese, group IV metals from titanium and zirconium, and alkali metals from potassium, calcium, and magnesium.

[0067] The spent Fischer-Tropsch catalyst can originate from any known process involving a fixed-bed, bubbling-bed, or bubble-column catalyst. It can be in the form of beads, extruded material, or powder, depending on the process from which it originates.

[0068] Preferably, the spent catalyst is obtained via a Fischer-Tropsch bubble column process and withdrawn with a mixture of heavy hydrocarbons (waxes) produced by the reaction. At this stage, the catalyst metal is still at least partially in its metallic form (zero oxidation state). Preferably, it is in powder form.

[0069] The solid obtained after this treatment can then be calcined under controlled conditions to remove a larger fraction of the hydrocarbons still present in the catalyst after extraction. This calcination is advantageously carried out in the presence of oxygen-depleted air (for example, containing an oxygen content of 10% by volume or less) following a series of controlled temperature ramps and plateaus to avoid exothermic reactions associated with the combustion of coke and linear hydrocarbon molecules. Generally, a small amount of carbon remains after this heat treatment step.

[0070] The oxide support of said catalyst source of the process according to the invention is usually a porous solid chosen from the group consisting of: aluminas, silica, silica-aluminas or even titanium or magnesium oxides used alone or in mixture with alumina or silica alumina.

[0071] In another preferred case, the oxide present in the support of said catalyst source of the process according to the invention is a silica alumina containing at least 70% by weight of alumina relative to the total weight of the composite support. The silica content in the support is at most 30% by weight relative to the total weight of the support, most often less than or equal to 20% by weight, preferably less than or equal to 15% by weight.

[0072] According to a particularly preferred variant, the support of the source catalyst consists of alumina, silica or silica-alumina.

[0073] The support is advantageously presented in the form of irregular and non-spherical beads, extrudates, pellets or agglomerates whose specific shape may result from a crushing step.

[0074] According to a particularly preferred variant, the support for the source catalyst is in the form of a powder with an average particle size between 30 and 200 pm, preferably between 40 and 150 pm and even more preferably between 50 and 120 pm.

[0075] The content of Group VIII metal Ml is between 10 and 35% by weight of Group VIII metal relative to the total weight of the dry catalyst, preferably between 15 and 30% by weight, and preferably between 17 and 25% by weight.

[0076] The catalyst source of the process according to the invention may also include boron as a dopant. The dopant is an added element which, in itself, has no catalytic properties but which can improve the stability of the catalyst and limit its deactivation and deselectivation.

[0077] The boron content in said source catalyst is then preferably between 0.05 and 0.25% by weight expressed as Boron element relative to the total weight of the dry catalyst, preferably between 0.07 and 0.015% by weight expressed as B, and most preferably between 0.09 and 0.12% by weight expressed as Boron element.

[0078] The source catalyst of the process according to the invention may also comprise, in addition to the Group VIII metal M1, another Group VIII metal and preferably a noble metal, preferably selected from platinum, palladium, ruthenium, and rhenium, alone or in mixtures. The noble metal content in said source catalyst is then preferably between 25 and 500 ppm by weight expressed as an element relative to the total weight of the dry catalyst, preferably between 25 and 100 ppm by weight expressed as an element, and most preferably between 30 and 70 ppm by weight expressed as an element.

[0079] According to the invention, the catalyst does not comprise any metal from group VI B and preferably does not comprise any metal selected from molybdenum and tungsten. The metal M1 of the source catalyst is preferably essentially in reduced form (zero oxidation state).

[0080] The source catalyst of the process according to the invention advantageously does not contain sulfur or nitrogen. The sulfur content in said source catalyst is preferably less than 1% by weight, expressed as an element relative to the total weight of the dry catalyst, preferably less than 0.1%, and most preferably less than 0.01% by weight. The nitrogen content in said source catalyst is preferably less than 0.1% by weight, expressed as an element relative to the total weight of the dry catalyst, preferably less than 0.05%, and most preferably less than 200 ppm by weight.

[0081] The catalyst source of the process according to the invention may comprise coke but also non-aromatic carbon derived from the products of the Fischer-Tropsch reaction, essentially in the form of long paraffin and olefin chains. It should be noted that the term "coke" in this application refers to 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 and carbon content of the source catalyst directly discharged from the FT reactor before its implementation in the process according to the invention is advantageously greater than 30%.

[0083] According to one embodiment of the invention, the catalyst source of the process according to the invention may comprise or be composed of the fines produced during the unloading operation of the spent catalyst from the industrial unit from which it is removed, or during regeneration. In this case, and according to a variant of the process, the fines may be eliminated at any stage of the process of the invention, and in particular before the metal(s) extraction stage or before the impregnation stage of the metal(s) depleted catalyst.

[0084] The steps in the manufacturing process of a catalyst based on recycled metals according to the invention

[0085] According to the invention, the object of the invention is a process for producing a recycled catalyst comprising at least one metal M1 of group VIII and not comprising any metal of group VI B, and optionally another metal chosen from the metals of group VIII (preferably platinum) and / or boron, and a support based on oxide(s), characterized in that said process comprises the recycling of at least a part of the metal(s) of a source catalyst comprising a metal common to the recycled catalyst to be produced, the process comprising at least: - a step of removing at least a part of the carbon present on the source catalyst comprising at least one step of washing the source catalyst with an organic solvent, and / or at least one step of heat treatment of the source catalyst at a temperature below 300°C in the presence of a gas containing air, without a heat treatment step in the presence of a gas chosen from oxygen,hydrogen sulfide and hydrogen, at a temperature above 300°C,

[0086] - Then, an extraction by an extraction solution of the metal Ml and possibly of another metal chosen from the metals of group VIII and preferably platinum and / or boron of said catalyst from the step of removing at least part of the carbon, to obtain a solution of extracted metal(s),

[0087] - then at least one step of impregnating a support with at least one impregnation solution derived from said solution of extracted metal(s), to obtain an impregnated support, said extracted metal(s) remaining in liquid phase from extraction until impregnation,

[0088] - and a drying stage and a calcination stage of the impregnated support obtained in the stage.

[0089] Steps (a) for removing at least some of the carbon present on the source catalyst: preliminary step(s) to extraction

[0090] Before the metal extraction stage, a step to remove at least some of the carbon is necessary, in particular to remove the majority of the wax (long paraffins with up to 90 carbon atoms) which is solid at room temperature.

[0091] According to the invention, the process includes a step of removing at least some of the carbon present on the source catalyst comprising at least one step of washing the source catalyst with an organic solvent, and / or at least one step of heat treating the source catalyst at a temperature below 300°C in the presence of a gas containing air, without a step of heat treating at a temperature above 300°C and carried out in the presence of a gas selected from oxygen, hydrogen sulfide and hydrogen prior to the extraction step.

[0092] The mandatory step (a) consists of partially removing the carbon, in the form of waxes and / or coke deposited on the surface of the catalyst (hydrocarbons and coke) before step (b) of metal extraction.

[0093] According to the invention, the washing step a1) of the source catalyst is carried out in the presence of an organic solvent, preferably maintained at its boiling point, to remove all or part of the coke and Fischer-Tropsch reaction products (wax) that may be deposited on the catalyst. The organic solvent used in the washing step a1) is preferably maintained at its boiling point and is preferably selected from aromatic solvents, preferably toluene and / or xylene, linear hydrocarbon solvents comprising between 3 and 12 carbon atoms, preferably hexane and / or heptane, and linear or branched alcohols comprising between 3 and 12 carbon atoms, alone or in mixtures.

[0094] In a preferred embodiment, the organic solvent of the washing step a1) is an aromatic solvent selected from toluene and xylene, alone or in mixture.

[0095] This washing step a1) of the wax preferably includes washing the source catalyst with a hydrocarbon solvent at its boiling point (e.g., toluene and / or xylene), at a temperature between 80°C and 180°C, preferably between 90°C and 150°C, for a duration of between 1 and 24 hours, preferably between 2 and 12 hours. The tool used in the laboratory to perform this washing is a Soxhlet apparatus, which allows for thorough extraction of the hydrocarbon chains present in and on the catalyst by recirculating the solvent over the catalyst.

[0096] For example, the at least partially spent source catalyst is extracted from the reactor and sent to a facility for the extraction of wax and some of the coke in order to wash the catalyst in said facility.

[0097] The washing step is advantageously carried out in a stream of organic solvent heated to its boiling point. The solvent vaporizes and then flows through the catalyst bed to be washed, in a Soxhlet-type washing column, carrying away carbon in the form of long chains and coke. The washing process lasts between 1 and 24 hours, and preferably between 2 and 12 hours.

[0098] According to the invention, step a1) is carried out without a heat treatment step at a temperature above 300°C and carried out in the presence of a gas chosen from oxygen and hydrogen.

[0099] Preferably, the catalyst contains, at the end of step a1) of washing, a carbon content greater than 1% and less than 15%, expressed as a percentage by weight in relation to the total weight of said dry washed catalyst.

[0100] Preferably, the carbon content, expressed as a percentage by weight relative to the total weight of the dry washed catalyst, is between 2 and 15% by weight, preferably between 4 and 12% by weight, and most preferably between 6 and 10% by weight. The coke content is determined according to ASTM D5373. In accordance with the invention, at least one heat treatment step (a2) of the source catalyst at a temperature below 300°C in the presence of an air-containing gas is carried out alone or in conjunction with said washing step (a1).

[0101] Preferably, the heat treatment step a2) is carried out after the washing step a1) in the presence of a solvent and consists of removing some of the residual carbon by heat treatment preferably in the presence of a gas containing oxygen, usually air.

[0102] Preferably, the gas flow rate, measured 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 30 to 1000 NL.h-1, and particularly preferably 50 to 300 NL.h-1. The total duration of the heat treatment step a2) is preferably 4 hours or more, more preferably 8 hours or more, and particularly preferably 15 hours or more.

[0103] According to the invention, step a2) is carried out at a temperature below 300°C, preferably between 100 and 300°C, preferably between 150 and 300°C and most preferably between 200 and 270°C.

[0104] The source catalyst from step a), and in particular from steps a1) and / or a2), is composed of the oxide support and the active phase, which consists of at least one metal from Group VIII and does not include any metal from Group VI B, and optionally another metal chosen from among the Group VIII metals (preferably platinum) and / or boron. The regenerated catalyst is characterized by a specific surface area between 20 and 300 m². 2 / g, preferably between 50 and 280 m 2 / g, preferably between 80 and 240 m 2 / g, preferably between 100 and 200 m 2 / g.

[0105] The porous volume of the source catalyst (used and then regenerated here) is generally between 0.2 cm3 / g and 1 cm3 / g, preferably between 0.25 cm3 / g and 0.8 cm3 / g, most preferably between 0.3 and 0.6 cm3 / g.

[0106] The catalyst from step a) and in particular from steps a1) and / or a2) contains residual carbon at a content greater than 1% and less than 15% by weight relative to the total weight of the catalyst, preferably a carbon content between 3% and 15% by weight relative to the total weight of the catalyst, preferably between 5% and 12% by weight and particularly preferably between 6% and 10% by weight.

[0107] It should be noted that the term "residual carbon" in this application refers to carbon (coke) and possibly long paraffins present in the porosity remaining in the washed catalyst, which may also be regenerated after washing and regeneration of the spent Fischer-Tropsch catalyst. This residual carbon content in the regenerated hydrotreating catalyst is measured according to ASTM D5373.

[0108] Extraction step (b)

[0109] According to the invention, the process includes a step b) of extraction by an extraction solution of the metal Ml of group VIII and preferably of cobalt, and possibly of another metal chosen from the metals of group VIII (preferably platinum) and / or of boron of said catalyst from the step of removing at least part of the carbon, to obtain a solution of extracted metal(s).

[0110] According to this step, the catalyst from step a) of removing at least part of the carbon is advantageously brought into contact with an extraction solution containing at least one solvent.

[0111] Preferably, the extraction solution comprises a polar protic solvent, preferably selected from the group consisting of methanol, ethanol, and water, or alternatively, a mixture of water and ethanol, water and methanol, or water and citric acid. In a specific embodiment, the extraction can be carried out in the presence of water alone, without the addition of any organic agent.

[0112] The extraction solvent may advantageously be organic or aqueous, or both. Most preferably, the solvent used in the extraction solution consists mainly of water and may advantageously also include an organic compound. In the case of an aqueous solution, the pH of said solution may advantageously be modified by the optional addition of an acid or a base. The extraction solution generally has a pH between 0.1 and 8.5, preferably between 0.5 and 6, and preferably between 1 and 4.

[0113] In the case where the solvent is organic, it may include any polar protic solvent known to those skilled in the art. Preferably, the solvent is an organic compound having complexing and possibly acidic properties, preferably either at least one compound having both properties, or a combination of at least one acidic compound and at least one complexing compound, or only at least one complexing compound. Said organic compound is chosen from a compound having one or more chemical functionalities selected from a carboxylic acid, phosphonic acid, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide function, or compounds including a furanic acid ring, or sugars. In a preferred embodiment, said organic solvent (or at least one of them when there are several) may 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, 2-hydroxy-4-methylthiobutanoic acid, glutamic acid, N-acetylglutamic acid, alanine, glycine, 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, alone or in mixtures.

[0114] Preferably, said organic solvent is selected from acetic acid, oxalic acid, malonic acid, glutaric acid, lactic acid, citric acid, tartaric acid, succinic acid, ascorbic acid, salicylic acid, maleic acid, malic acid and even more preferably, from citric acid, acetic acid, oxalic acid, and lactic acid, alone or in mixture.

[0115] The chemical compounds in this group do indeed exhibit both acidic and complexing properties.

[0116] In a preferred embodiment, said organic solvent (or at least one of them) may be selected 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, γ-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, alone or in mixtures.

[0117] The chemical compounds in this group do indeed exhibit complexing properties.

[0118] Advantageously, the extraction solution also includes at least one mineral acid, in particular phosphoric acid, nitric acid, or boric acid. This combination of a complexing organic compound and a mineral acid has proven very effective, allowing for both good extraction of the target metals and the creation of a sufficiently acidic environment, especially when the impregnation of the support using this solution must be carried out in an acidic environment, and even more so when the final catalyst must contain phosphorus, particularly when phosphoric acid is chosen.

[0119] The concentration of each organic compound in the extraction 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.

[0120] When several organic compounds are present, the different molar ratios apply to each of the organic compounds present.

[0121] In one embodiment of the invention, the extraction solution may also contain phosphorus. The presence of phosphorus in the extraction solution promotes metal extraction. The addition of phosphorus in the form of phosphoric acid (H3PO4) also lowers the pH of the solution, which is also generally beneficial for the extraction of metals contained in the source catalyst. Other mineral acids besides phosphoric acid may also be used, in particular, nitric acid or boric acid.

[0122] The preferred phosphorus precursor is phosphoric acid (H3PO4), but its esters and salts, such as ammonium phosphates, are also suitable, as are polyphosphates. Without being linked to any specific theory, it appears that combining phosphoric acid with an organic acid having a pKa greater than 1.5—that is, a weak organic acid—results in a synergistic effect on metal extraction that is not predictable when using phosphoric acid or the organic acid alone. Extraction in the presence of two specific acids allows for very good dissolution of the metal phases. In one embodiment according to the invention, the extraction solution may also contain an oxidant to promote metal extraction. Preferably, the oxidant in the extraction solution is hydrogen peroxide. When an oxidant is present, the concentration is generally between 0.1 and 5.0 mol / L.1 .

[0123] In general, the operating conditions of step (b) are chosen to maximize the extraction of metals from the source catalyst, while minimizing the dissolution of the metal(s) in the support of said source catalyst, and limiting the amount of organic compound so that it is not in excessive excess relative to the optimal amount of organic compound required for the impregnation step to obtain high-performing catalysts. The aim is also to minimize the amount of extraction solution used, in order to obtain the most concentrated metal solution possible at the end of the extraction without reaching the solubility limit, which would lead to metal precipitation. This limits the need to concentrate the solution before using it in the impregnation solution or as the impregnation solution itself.

[0124] The catalyst from the step of removing at least part of the carbon is brought into contact with the extraction solution under the following conditions: temperature: between 10 and 150°C, in particular between 15 and 95°C,

[0125] - Pressure: between atmospheric pressure and 20 bar, specifically at atmospheric pressure or at most 10 bar

[0126] - duration: between 1 minute and 20 hours, preferably between 5 and 400 minutes, preferably between 60 and 360 minutes.

[0127] Preferably, the tool(s) performing the contacting operation do not have heating equipment, and the contact temperature is regulated by the temperature of the extraction solution. The temperature of the extraction solution can be between 15, 20, or 25°C and 95°C, and preferably between 30°C and 90°C, and even more preferably between 50°C and 85°C. It can therefore be at ambient temperature, or have been heated, for this specific contacting step. It can also be at a given temperature, particularly above ambient temperature, because it originates, at least in part, from the recycling of liquid effluents produced in the process according to the invention and already within this temperature range.

[0128] The amount of extraction solution used in this step is preferably as small as possible to achieve the desired effect, as described above. Preferably, this step (b) is carried out by contacting the source catalyst with a volume of said solution between 1.5 and 60 times the volume of the source catalyst. Preferably, the volume of said solution is between 2 and 30 times the volume of the source catalyst, and more preferably between 2 and 20 times the volume of the source catalyst.

[0129] All contact methods, whether single-stage or multi-stage (co-current, counter-current, or cross-current), are possible for implementing step (b) in continuous mode. Batch contact is also an option. For example, contact can be achieved by immersion or by submerging the extraction solution, for instance, by distributing the trickling extraction solution over the source catalyst, which may be set in motion.

[0130] At the end of step (b), the solution is separated from the solid residue to obtain, on the one hand, a metal-depleted catalyst, and, on the other hand, the metallic solution of the extracted metal(s) to be used in the following steps (c), (d), (e), (f), (g), (h), (i), (j), or (k). Preferably, the residual metal content of the metal-depleted catalyst (sum of the contents of the different metals in said catalyst expressed as oxide) is less than 12 wt%, preferably less than 10 wt%, and most preferably less than 7 wt% and greater than 5 wt%. Any liquid / solid separation method may be used, such as filtration or dewatering, for example, gravity separation. Preferably, the separation step is carried out using a filter press.

[0131] The process according to the invention includes, either mandatorily or optionally, the following steps (successive but not necessarily consecutive):

[0132] - at least one step (a1, a2) of processing the source catalyst,

[0133] - extraction (b) by an extraction solution of the metal(s) of said catalyst obtained from steps a1) and / or a2), to obtain a solution of extracted metal(s) and a metal-depleted catalyst,

[0134] - at least one optional step (c) of purifying the solution of extracted metal(s), produced in step (b), to remove all or part of any impurities,

[0135] - at least one optional step (d) of concentrating the solution of extracted metal(s),

[0136] - at least one optional step (e) of adjusting the composition of the solution of extracted metal(s) from step (b), (c) or (d)

[0137] - the liquid impregnation (f) of a porous support by at least one impregnation solution derived from said solution of extracted metal(s) obtained at the end of step (b), (c), (d) or (e), with a possible addition of metal(s), to obtain an impregnated support, said extracted metal(s) remaining in liquid phase from extraction until impregnation, (depending on whether steps (c), (d) and (e) are carried out or not and according to the order in which they are carried out)

[0138] - a drying step and a calcination step (g) of the impregnated support obtained in the step

[0139] (f).

[0140] - advantageously a reduction step (h) of the dried and calcined impregnated support obtained in step (g)

[0141] - one or more optional heat treatment step(s) (i) of the metal / metal depleted catalyst from step b)

[0142] - the optional (j) liquid impregnation of the metal-depleted catalyst obtained in step (i) with an impregnation solution, said impregnation solution being derived from said solution of extracted metal(s) obtained in step (b), (c), (d) or (e), or from an impregnation solution comprising "fresh" cobalt, i.e., cobalt not obtained in step b) of extraction according to the invention. In the case of using the impregnation solution of extracted metal(s) obtained in step (b), (c), (d) or (e), a possible addition of metal(s) is possible. Said extracted metal(s) remain in the liquid phase from extraction until impregnation.

[0143] - an optional drying step and calcination step (k) of the impregnated support obtained in step (j) (in the case where said step j) is implemented),

[0144] It should be noted that step (b) is carried out before step (f), and that the drying and calcination step

[0145] (g) are done after step (f). The reduction step (h) is done after step (g). The optional steps (c), (d), (e) are preferably done in the order of the statement of steps indicated above, i.e. step (c), then (d) then (e), but they can also be carried out in a different order (such as dce, or dec, or ced, or ecd, or edc).

[0146] It is also noted that steps (f) and (g) on ​​the one hand and (j) and (k) on the other hand can be followed respectively by at least one further impregnation step (f') and a drying and calcination step (g'), respectively followed by an impregnation step (j') and a drying and calcination step (k').

[0147] Preferably, three steps of impregnation, drying and calcination are implemented. In the case where steps (f') or (j') are intercalated as mentioned above, these can advantageously be carried out using an impregnation solution from said solution of extracted metal(s) obtained in step (b), (c), (d) or (e), or from an impregnation solution comprising "fresh" cobalt, i.e. not from step b) of extraction according to the invention.

[0148] Advantageously, the process for producing a recycled catalyst may include at least one post-treatment step of the extracted metal(s) solution prior to impregnation, chosen from at least one of the following treatments: purification, concentration, adjustment of the solution's composition by dilution, or modification of the solution's composition by adding or removing, totally or partially, at least one compound. These post-treatments aim to bring the extraction solution into the conditions required to serve as an impregnation solution. Concentration, by removing at least some of the solvent / non-metallic compounds from the solution, will make it more effective and bring it closer to the concentrations required for impregnation in conventional processes for impregnating new catalysts.The same applies when, for example, adding to this solution the constituent elements of the catalyst to be produced, in particular adding at least one metal not present in the solution, or present in insufficient quantity.

[0149] Step (c) (Optional): Purification

[0150] The process according to the invention may advantageously include an optional step (c) of purifying the extracted metal(s) solution produced in step (b) to remove all or part of any impurities that may be contained in said metal solution, in particular impurities potentially present on the source catalyst or related to partial dissolution of the support of said catalyst. Step (c) may advantageously be carried out in a single step or in several successive steps.

[0151] If the extracted metal(s) solution contains suspended solids after the separation step, at the end of step (b), any known method for removing these suspended solids may advantageously be used in step (c). Preferably, this removal is carried out by filtration (e.g., microfiltration and ultrafiltration using a cross-flow filter). Other methods include centrifugation or coagulation.

[0152] For dissolved impurities, such as aluminum or silicon compounds, all known methods may be used in this step (c), in particular and preferably, solid sorption, precipitation, and solvent extraction, taking care not to simultaneously remove the extracted metals of interest. If the purification step (c) results in a second, undesirable solution containing solvent, this solution may advantageously be recycled in the extraction step (b) if its impurity content remains low.

[0153] Step (d) (Optional): Concentration

[0154] The process according to the invention may also advantageously include a step (d) of concentrating the extracted metal(s) solution from step (b) or (c) by removing a portion of the solvent and all or part of the organic compound contained in said metal solution. This step may be necessary if the metal concentrations are too low compared to the concentrations required for impregnation. Any known method for removing a portion of a solvent from a solution is considered. Step (d) may advantageously be carried out in a single step or in several successive steps. All or part of the solvent, whether or not it contains an organic compound, extracted from said metal solution in this step (d), may advantageously be recycled in the extraction step (b).

[0155] Preferably, and particularly when the extracted metal(s) solution is aqueous, step (d) is advantageously carried out by evaporation concentration. In this case, neutralization is preferably performed so that the effluent enters the evaporator at a pH between 5 and 7. This pH control helps to limit co-distillation, unless it is desired for the co-removal of the solvent and some of the organic compound, and also to minimize the precipitation of metal oxides. Preferably, all or part of the distillate is advantageously recycled to the extraction step (b).

[0156] When only the removal of part of the solvent is desired, besides evaporation concentration, the preferred techniques are membrane techniques, and, very preferably, nanofiltration, reverse osmosis and pervaporation, solvent extraction or cryoconcentration.

[0157] When you want to remove solvent and organic compound(s) when they are used, a preferred technique is evaporation concentration.

[0158] Step (e) of adjusting the composition of the metallic solution (Optional)

[0159] The process according to the invention may also advantageously include a step (e) of adjusting the composition of the extracted metal(s) solution, which consists of modifying said metal solution from step (b), (c), or (d) by adding and / or removing certain constituents. Metal 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 production of the recycled catalyst according to the invention in the impregnation step (f).

[0160] Case where several metals Ml from group VIII as well as boron coexist on the source catalyst:

[0161] Even if it is desired that the catalyst according to the invention has a formulation identical to that of the source catalyst, the ratios between metals of the metal solution / extracted metal(s) are potentially to be adjusted, firstly because the step of removing at least part of the carbon - step (a) - from the catalyst can modify the initial metal contents of the source catalyst, and secondly because the extraction step (b) can induce different extraction rates for each of the metals.

[0162] The adjustment of the metal ratios is achieved either by adding a makeup solution containing one or more of the metals, or by directly dissolving one or more metal precursors in the metal solution obtained from step (b), (c), or (d), the latter being preferred. As an example for cobalt metal precursors, the cobalt sources that can be used are advantageously chosen from among cobalt oxides, hydroxides, hydroxycarbonates, carbonates, and nitrates. Cobalt nitrate is preferred.

[0163] Cases where there is an excess of the metal extraction solvent:

[0164] The extracted metal(s) solution from step (b), (c), or (d) may contain an excess of solvent relative to the desired impregnation solution. The ratios of organic compound to metals can be adjusted in two ways. The first 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 will consist of a mixture of recycled and virgin metals.

[0165] If the excess solvent is too great to use the first method (i.e., the amount of recycled metals incorporated into the final catalyst is not significant, for example, less than 5% of the total amount of metals), the second method consists of removing all or part of the excess organic compound from the metal solution. In this case, the organic compound can advantageously be recycled in step (b). For this purpose, any method known to those skilled in the art for separating a solvent from a metal solution is considered. Step (f): Impregnation

[0166] According to the invention, the process includes at least one step f) of impregnating a support with at least one impregnation solution from said solution of extracted metal(s) from step (b), (c), (d) or (e), to obtain an impregnated support, said extracted metal(s) remaining in liquid phase from extraction until impregnation.

[0167] In said step (f), a porous support, or a catalyst already containing one or more metals (according to the definition of "support" given above), is brought into contact with said solution of extracted metal(s) obtained in step (b), (c), (d), or (e). According to step (f), the contacting of said porous support or catalyst and the metal salt in solution may be carried out by any known method, such as, for example, ion exchange, dry impregnation, excess impregnation, vapor deposition, etc. The contacting may advantageously take place in one step or in several successive steps.

[0168] According to a preferred method, step (f) of bringing said support into contact with said metallic solution is carried out by dry impregnation.

[0169] Dry impregnation involves introducing a volume of impregnation solution equal to or slightly less than the porous volume of the substrate or catalyst. Dry impregnation allows for the complete deposition of all the components of the impregnation solution onto a given substrate or catalyst.

[0170] Step (f) 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 dry impregnation, using the impregnation solution.

[0171] According to a first embodiment, the substrate can be impregnated using the extracted metal(s) solution from step (b), (c), (d), or (e), and a supplement of at least one metal from Group VIII. This supplement can be either premixed with the extracted metal(s) solution or added separately to the device where the substrate impregnation takes place. The supplement can be in liquid or non-liquid form; it will more likely be in liquid form if added separately, and can be in liquid or solid form if added to the extracted metal(s) solution prior to the actual impregnation.

[0172] Preferably, at least part of the extracted metal(s) solution obtained after any processing step of said extracted metal(s) solution can be reused, particularly as a top-up to said extraction solution. This limits the process's consumption of extraction solvent. Preferably, the extracted metal(s) solution can be concentrated to remove at least part of the extraction solvent, and at least part of this removed solvent is then reused as a top-up to the extraction solution. Again, this reuse helps limit the process's consumption of extraction solvent.

[0173] According to another embodiment of the process according to the invention, the support on which the impregnation step is carried out with the impregnation solution from the solution of metals / extracted metal(s), can be pre-impregnated with a so-called fresh or conventional impregnation solution, that is to say not produced by the process according to the invention and in particular not produced by steps (b), (c), (d) or (e).

[0174] A "conventional" impregnation solution is defined as a "fresh" solution containing, in a known manner, precursors of Group VIII metals, preferably "fresh" cobalt precursors, i.e., not recycled according to the process of the present invention. After impregnation with the impregnation solution according to the invention, the support can also be post-impregnated with a conventional impregnation solution. The purpose of this pre-impregnation and / or post-impregnation of the support is, in particular, to adjust, if necessary, the quantity of metals and / or dopants so that the final catalyst has the desired composition. The objective of this post- or pre-impregnation can also be to add the metal in the form of different metallic precursors in order to impart specific properties to the catalyst.

[0175] In the case where impregnation with another group VIII metal precursor, or with a conventional metal solution is carried out before or after impregnation of the extracted metal / metal(s) solution from step (b), (c), (d) or (e), it is advantageously followed by various maturation, drying and calcination steps under conditions (temperature, time, atmosphere) adapted to the properties that a person skilled in the art wishes to impart to the metals from the conventional solution.

[0176] In one embodiment of the invention, the support on which impregnation (j) is carried out with the impregnation solution from the extracted metal(s) solution obtained in step (b), (c), (d), or (e) may be obtained from step (i), the heat treatment of the metal-depleted catalyst obtained in step (b), or from step (k), the drying and calcination of the depleted and then impregnated catalyst obtained in step (j). This support contains a spinel between the Group VIII metal (preferably cobalt) and the alumina of the support. This allows for the production of a so-called stabilized support before the addition of the Group VIII metal (M1), preferably cobalt, which is considered active by impregnation (f) with the impregnation solution obtained from the extracted metal(s).

[0177] Preferably, the support on which the impregnation is carried out with the impregnation solution from the extracted metal(s) solution is calcined at very high temperature in order to form a spinel between the cobalt and the alumina of the support before the addition of the group VIII metal and preferably cobalt by impregnation of said impregnation solution.

[0178] The stabilized support has the particularity that after the impregnation of the solution of extracted metal(s) and preferably cobalt on the support, a step k) of high temperature calcination is advantageously carried out to form a mixed phase between the alumina of the support and the metal VIII, preferably cobalt, leading to a hydrothermally resistant support.

[0179] Step (f) is advantageously carried out at a temperature between 10°C and 95°C, at a pressure between atmospheric pressure and 20 bar, preferably at atmospheric pressure, and for a duration preferably between 1 minute and 20 hours, preferably between 1 and 200 minutes. Step (f) is preferably carried out at a temperature between 10°C and 60°C, preferably at ambient temperature.

[0180] 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.

[0181] Each maturation step described in the present invention 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 ambient temperature. Generally, a maturation time of between ten minutes and forty-eight hours, and preferably between thirty minutes and two hours, is sufficient.

[0182] In the embodiment in which step (f) is carried out via at least two impregnation cycles, each impregnation is advantageously followed by a drying step and a calcination step.

[0183] The support implemented in step (f) of the process according to the invention advantageously comprises at least one oxide and is usually a porous solid selected from the group consisting of: aluminas, silica, alumina-silica.

[0184] The oxide support advantageously has a total pore volume between 0.3 and 0.8 mL / g, preferably between 0.4 and 0.7 mL / g.

[0185] The specific surface area of ​​the oxide support is advantageously between 150 and 300 m² 2 .g' 1 preferably between 100 and 250 m 2 .g' 1 , preferably between 120 and 200 m 2 .g _ 1 The specific surface area is determined in the present invention by the BET method according to ASTM D3663. The oxide support of the recycled catalyst according to the invention may advantageously be of the same nature as the support of the source catalyst, a description of which has already been given above.

[0186] In another preferred case, the oxide present in the support of said catalyst of the process according to the invention is an alumina-silica containing at least 80% by weight of alumina relative to the total weight of the composite support. The silica content in the support is advantageously at most 20% by weight relative to the total weight of the support, most often less than or equal to 15% by weight, preferably less than or equal to 10%.

[0187] According to a particularly preferred variant, the support consists of alumina, silica or silica-alumina.

[0188] Alternative embodiment

[0189] Another embodiment involves using a portion of the extracted metal(s) solution, when it contains an acidic extraction solvent, to introduce it during the synthesis of the support containing alumina and optionally silica. This aqueous cobalt solution is used for the preparation of the Fischer-Tropsch catalyst support. The solution is introduced during the mixing step of the precursors constituting the catalyst support. This solution has the advantage of having a pH between 2 and 4, i.e., a pH equivalent to that of the suspension required to prepare the catalyst support. Mixing this solution with the precursors results in a suspension with a pH between 2 and 4, and preferably between 2.5 and 3.5. Preferably, this solution constitutes the sole source of cobalt in the suspension.

[0190] The suspension is then dried and shaped by spray drying. The suspension obtained from this solution has the advantage of not generating species that would require closed-circuit equipment for safety reasons, i.e., equipment with a sloughing column or condenser. The spray drying step produces a dried catalyst support containing cobalt. The support obtained by incorporating this solution has the advantage of already containing cobalt, eliminating the need for additional steps, such as impregnation followed by drying / calcination, to obtain a stabilized support.

[0191] The atomized support is then calcined at 800 to 1200°C to obtain a support containing a mixed phase, which may be cobalt aluminate. The catalyst support obtained after calcination has the advantage of containing stabilizing cobalt; therefore, no further stabilization steps are required to prepare the catalyst. The stabilized catalyst support will thus be considered a catalyst support stabilized with a 100% recycled cobalt solution.

[0192] Advantageously, the support used in step (f) comes from either step i) or k) according to the invention and is therefore indirectly derived from depleted catalyst obtained at the end of step b).

[0193] Step (g): Drying and calcination of the impregnated support

[0194] According to the invention, the impregnated support from step f) is subjected to a drying step and a calcination step in order to obtain the recycled catalyst according to the invention.

[0195] Preferably, the drying step of the impregnated substrate from step f) is carried out at a temperature below 200°C, preferably between 50 and 180°C, more preferably between 70 and 150°C, and most preferably between 80 and 130°C. The drying step is preferably carried out for a duration of between 10 minutes and 10 hours. Longer durations are not excluded, but do not necessarily provide any improvement. The drying step may advantageously be carried out by any known technique. It is advantageously carried out at atmospheric pressure or 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.Preferably, drying is carried out in the presence of nitrogen and / or air and is advantageously performed in a fluidized bed.

[0196] According to the invention, drying is followed by a calcination step. This eliminates organic extraction compounds or any counter-ions introduced by the addition of fresh metal. Following the drying step, a calcination step is advantageously carried out at a temperature between 250°C and 600°C, preferably between 300°C and 450°C, under an inert atmosphere (nitrogen, for example) or an atmosphere containing oxygen (air, for example). The duration of this heat treatment is advantageously between 0.5 and 16 hours, preferably between 1 and 4 hours. After this treatment, the active phase is generally in oxide form.

[0197] The active phase of the recycled catalyst targeted by the process according to the invention is generally of the same nature and quantity as that described above for the so-called spent catalyst. It is also possible to produce a recycled catalyst according to the invention that is less metal-rich than the spent catalyst used, particularly if this avoids concentrating the extract solution before impregnation.

[0198] The quantity of recycled metals contained in the catalyst according to the invention is between 1% and 100% wt of the metals contained in the catalyst produced according to the invention, preferably between 10% and 100% wt, preferably between 20% and 100% wt, and even more preferably between 50% and 100% wt of the metals contained in the catalyst according to the invention.

[0199] It should be noted that the catalyst produced according to the invention may have a different formulation than the spent catalyst used to recover the metals, and different quantities and ratios of metals: thus, as mentioned above, a spent catalyst with a high metal content can, according to the invention, be used to produce a catalyst with a lower metal content (or vice versa). This makes it possible, where appropriate, to avoid a post-extraction solution concentration step at the end of step (b) or at least to reduce its intensity / duration.

[0200] Step (h): step of activation of the recycled catalyst by reduction

[0201] Before its use in the Fischer-Tropsch process, the recycled catalyst produced by the process according to the invention undergoes an activation step, preferably by reduction. The activation is preferably carried out in a reducing environment, i.e., in the presence of hydrogen, in order to transform the metal oxides into metal, preferably Co. The activation is advantageously achieved by injecting a flow containing hydrogen, and preferably pure hydrogen, onto the catalyst. This activation can advantageously be carried out in situ or ex situ (inside or outside the reactor) of the Fischer-Tropsch process reactor, preferably ex situ according to the invention, at temperatures between 200 and 600°C, and more preferably between 300 and 500°C.

[0202] Optional heat treatment step(s) (i) of the metal-depleted catalyst from step b)

[0203] The metal-depleted catalyst from step b) may advantageously undergo one or more optional heat treatment steps. Preferably, the metal-depleted catalyst from step b) may advantageously undergo a drying step at a temperature below 200°C, preferably between 50 and 180°C, more preferably between 70 and 150°C, and most preferably between 80 and 130°C. The drying step is preferably carried out for a duration of between 10 minutes and 10 hours. Longer durations are not excluded, but do not necessarily provide any improvement. The drying step may advantageously be carried out by any known technique. It is advantageously carried out at atmospheric pressure or 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. Most preferably, drying is carried out in the presence of nitrogen and / or air.

[0204] Drying is advantageously followed by a calcination step. This eliminates the extracted organic compounds. After the drying step, a calcination step is advantageously carried out at a temperature between 300°C and 1200°C, preferably between 350°C and 1100°C, under an inert atmosphere (nitrogen, for example) or under an oxygen-containing atmosphere (air, for example). The duration of this heat treatment is advantageously between 0.5 and 16 hours, preferably between 2 and 6 hours. After this treatment, the metallic phase is generally in oxide form.

[0205] Step (j) of impregnation, optional by liquid means of the catalyst depleted in dried metal, and possibly calcined.

[0206] The process may advantageously include a step j) of impregnating the depleted catalyst from step (i) with an impregnation solution from said solution of metal(s) extracted from one of steps (b), (c), (d) or (e), or with an impregnation solution comprising "fresh" cobalt, i.e., not from step b) of extraction according to the invention, to obtain an impregnated support.

[0207] In said step (j), the depleted catalyst from step (i) is contacted with said metal solution obtained in step (b), (c), (d), or (e), or with an impregnation solution comprising "fresh" cobalt. Depending on step (j), the contacting of said depleted catalyst and the solution can be carried out by any known method, such as ion exchange, dry impregnation, excess impregnation, vapor deposition, etc. The contacting can advantageously take place in one step or in several successive steps. According to a preferred method, step (j) of contacting said support with said metal solution is carried out by dry impregnation. Dry impregnation consists of introducing a volume of impregnation solution equal to or slightly less than the porous volume of the support or catalyst. Dry impregnation makes it possible to deposit all the constituents of the impregnation solution onto a given support or catalyst.Step (j) can advantageously be carried out by one or more excess impregnations of the solution or, preferably, by one or more dry impregnations, and, for example, by a single dry impregnation using the impregnation solution. Step (j) is advantageously carried out at a temperature between 10°C and 95°C, at a pressure between atmospheric pressure and 20 bar, preferably at atmospheric pressure, and for a duration preferably between 1 minute and 20 hours, preferably between 1 and 200 minutes. Step (j) is preferably carried out at a temperature between 10°C and 60°C, preferably at ambient temperature.

[0208] 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. Any maturation step described in the present invention 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 ambient temperature. Generally, a maturation time of between ten minutes and forty-eight hours, and preferably between thirty minutes and two hours, is sufficient. In the embodiment in which step (j) is carried out in a single step.

[0209] Step (k) of drying and calcination on depleted catalyst, impregnated from step (j)

[0210] The metal-depleted catalyst from step (j) may advantageously undergo a drying step at a temperature below 200°C, preferably between 50 and 180°C, more preferably between 70 and 150°C, and most preferably between 80 and 130°C. The drying step is preferably carried out for a duration of between 10 minutes and 10 hours. Longer durations are not excluded, but do not necessarily provide any improvement. The drying step may advantageously be carried out by any known technique. It is advantageously carried out at atmospheric pressure or 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. Most preferably, the drying is carried out in the presence of nitrogen and / or air.

[0211] Drying is advantageously followed by a calcination step. After the drying step, a calcination step is advantageously carried out at a temperature between 300°C and 1200°C, preferably between 350°C and 1100°C, under an inert atmosphere (nitrogen, for example) or under an oxygen-containing atmosphere (air, for example). The duration of this heat treatment is advantageously between 0.5 hours and 16 hours, preferably between 1 hour and 4 hours. After this treatment, the metallic phase is generally in oxide form.

[0212] EXAMPLES 1 (according to the invention): obtaining a solution no. 1 of Cobalt

[0213] We start with a spent Fischer-Tropsch catalyst containing cobalt on a silica alumina support, used in a slurry Fischer-Tropsch process. The catalyst is in the form of a powder with an average particle size of 80 µm. It was discharged coated into the solid hydrocarbon products at room temperature produced by the Fischer-Tropsch reaction (waxes). It was then washed in a Soxhlet apparatus in the presence of xylene heated to its boiling point for 6 hours. After this treatment, this catalyst, called the washed catalyst, contains 7.8 wt% carbon.

[0214] The washed catalyst contains cobalt. The composition of the catalyst is expressed as oxides and reported by the mass of dry catalyst: 23.4% wt. CoO (18.4% wt. cobalt).

[0215] A cobalt extraction step from this washed catalyst is carried out on a laboratory scale: 10 g of the washed catalyst and 25 g of extraction solution are placed in an Erlenmeyer flask. The extraction solution is an aqueous solution containing 176 g / L of citric acid. The Erlenmeyer flask is then placed on a stirring table, and the mixture is stirred for 2.5 hours at room temperature. The mixture is then filtered through sintered glass with a porosity of 5 to recover an aqueous cobalt solution, referred to as solution #1, and a solid residue containing the metal-depleted catalyst (Co). Analysis of the solution shows that it contains 34.3 g / L of cobalt. The calculated Co extraction rate is 51%. : obtaining a cobalt solution #2

[0216] A washed catalyst, as described in Example 1, is regenerated under a flow of oxygen-depleted air (10%) by means of a heat treatment at a temperature > 300°C, following a gradual temperature ramp (1°C / min ramp between 200 and 350°C, 2°C / min ramp from 350 to 550°C, then 4°C / min ramp from 550 to 650°C, with a 30-minute hold every 50°C), followed by a 2-hour hold at 650°C to prevent exothermic reactions due to the combustion of hydrocarbons and coke present in the spent catalyst. After this treatment, it contains 0.03% wt. carbon and is referred to as a washed-regenerated catalyst.

[0217] The washed-regenerated catalyst contains cobalt. The composition of the catalyst is expressed in terms of oxides and referred to the mass of dry catalyst: 25% by weight of CoO (20% by weight of cobalt.

[0218] A cobalt extraction step from this regenerated catalyst is carried out on a laboratory scale: 10 g of the washed and regenerated catalyst and 25 g of extraction solution are placed in an Erlenmeyer flask. The extraction solution is an aqueous solution containing 176 g / L of citric acid. The Erlenmeyer flask is then placed on a stirring table, and the mixture is stirred for 2.5 hours at room temperature. The mixture is then filtered through sintered glass with a porosity of 5 to recover an aqueous cobalt solution and a solid residue. Analysis of the solution shows that it contains 3.7 g / L of cobalt. The calculated cobalt extraction rate is 5%.

[0219] Table 1 below summarizes the rate of cobalt extracted as a function of the initial carbon content for examples 1 and 2.

[0220] Table 1

[0221] Example 3 (according to the invention): preparation of a Fischer-Tropsch catalyst by dry impregnation of solution no. 1 obtained in example 1: Catalyst A

[0222] Solution No. 1, obtained in Example 1, is used after evaporating 50% of the water volume using a rotary evaporator. The solution is maintained at a temperature of 50°C before being dry-impregnated onto a Siralox 5 silica alumina support with a pore volume measured by nitrogen porosimetry of 0.60 ml / g and a specific surface area of ​​150 m². 2The resulting solid is then dried at 100°C for 4 hours in air, then calcined at 400°C for 2 hours. The final cobalt content of the solid is 9 wt%. This operation is repeated once to obtain a Fischer-Tropsch catalyst precursor containing 17 wt% cobalt. This catalyst precursor is then reduced under pure hydrogen for 16 hours at 400°C after a temperature ramp of 4°C / min, then discharged under an inert material and coated in nC22 to protect it from reoxidation.

[0223] Example 4 (comparative): Preparation of a Fischer-Tropsch catalyst by dry impregnation with a commercial cobalt nitrate solution: Catalyst B. An aqueous solution of commercial cobalt nitrate containing 13 wt% cobalt is dry-impregnated onto support A described in Example 3. The resulting solid is then dried at 100°C for 4 hours in air, and then calcined at 400°C for 2 hours. The final cobalt content of the resulting solid is 13 wt%. This operation is repeated once to obtain a Fischer-Tropsch catalyst precursor containing 17 wt% cobalt. This catalyst precursor is then reduced under pure hydrogen for 16 hours at 400°C after a temperature ramp of 4°C / min, then discharged under an inert material and coated in nC22 to protect it from reoxidation.

[0224] Example 5: Evaluation of the catalytic performance of catalysts A compliant and B non-compliant.

[0225] The Fischer-Tropsch synthesis reaction is carried out in a continuous slurry reactor with a 10% (vol) concentration of catalyst in the slurry phase. Each catalyst is in powder form with a diameter between 40 and 150 microns. The test conditions are as follows:

[0226] Temperature = 230°C

[0227] Total pressure = 2 MPa

[0228] H2 / CO molar ratio = 2

[0229] CO conversion is maintained between 45 and 50% throughout the test. Syngas flow rates are adjusted to maintain CO conversion regardless of catalyst activity.

[0230] The intrinsic activity of the catalyst kO can be calculated as a function of a reference temperature, called Tref, and a pre-exponential reference factor kr: kO=kr.exB(-Ea / RTref)

[0231] With Ea= 119.51375 kJ / mol, F?=8.314 J / mol / K and r=0.003 mol / s.

[0232] The activity ratio between two catalysts can thus be expressed as a temperature difference, relative to a catalyst chosen as a reference base of activity k0,base.

[0233] By arbitrarily choosing 225°C as the reference temperature, the activity of the catalyst chosen as the base is expressed using the equation below: fcO.fegse-fcr. exp(Eo (498.15JÎ) )

[0234] A model is used to determine the reference temperature Tref, which allows experimental and calculated carbon monoxide consumption rates to converge. From this reference temperature (Tref), the activity ratio relative to the chosen reference catalyst is calculated using the following formula:

[0235] Activity (%) = k0 / k0base * 100 = exp(-Ea / (1 / 498.15 - 1 / Tref)

[0236] The results were calculated for catalysts A and B and are shown in Table 2 below. Alpha paraffin selectivities are also given, as well as the selectivity for methane and C5+ compounds. The alpha paraffin selectivity was measured via gas chromatography analysis of the reaction effluents, determination of paraffin content, and calculation of the slope of the curve log mol (%) = f(number of carbons), which corresponds to alpha.

[0237] The results in Table 2 show that the catalytic performance of catalysts A and B is equivalent in terms of both activity and selectivity when taking into account the uncertainties related to the implementation of a catalytic test and the accuracy of the analyses.

[0238] Table 2

Claims

DEMANDS 1. A process for producing a recycled catalyst comprising at least one metal Ml from group VIII and not comprising any metal from group VIB, and optionally another metal selected from the metals of group VIII and / or boron, and an oxide-based support(s), characterized in that said process comprises the recycling of at least a portion of the metal(s) from a source catalyst comprising a metal in common with the recycled catalyst to be produced, the process comprising at least the following steps: - a step for removing at least part of the carbon present on the source catalyst comprising at least one washing step (A1) of the source catalyst with an organic solvent, and / or at least one heat treatment step (A2) of the source catalyst at a temperature below 300°C in the presence of a gas containing air, without a heat treatment step in the presence of a gas selected from oxygen and hydrogen, at a temperature above 300°C prior to the extraction step, - Then, an extraction (B) by an extraction solution of metal M1 and possibly of another metal chosen from the metals of group VIII and preferably platinum and / or boron of said catalyst from the step of removing at least part of the carbon, to obtain a solution of extracted metal(s), - then at least one impregnation step (F) of a support by at least one impregnation solution derived from said solution of extracted metal(s), to obtain an impregnated support, said extracted metal(s) remaining in liquid phase from extraction until impregnation, - and a drying step and a calcination step (G) of the impregnated support.

2. A method according to claim 1, wherein the metal M1 of group VIII is Cobalt.

3. A process according to claim 1 or 2 wherein the support for the source catalyst is made of alumina, silica or silica-alumina.

4. A process according to any one of the preceding claims wherein the source catalyst also comprises, in addition to the group VIII metal M1, another group VIII metal preferably selected from platinum, palladium, ruthenium, and rhenium, alone or in mixture.

5. A process according to any one of claims 1 to 4, wherein the washing step (A1) of the source catalyst is carried out in the presence of an organic solvent maintained at its boiling point, selected from aromatic solvents, preferably toluene and / or xylene, and preferably linear hydrocarbon solvents comprising between 3 and 12 carbon atoms. hexane and / or heptane, and linear or branched alcohols comprising between 3 and 12 carbon atoms, alone or in mixtures.

6. A method according to any one of claims 1 to 5 wherein the heat treatment step (A2) is carried out after the washing step in the presence of an oxygen-containing gas and at a temperature preferably between 100 and 300°C, preferably between 150 and 300°C and most preferably between 200 and 270°C.

7. A process according to any one of claims 1 to 6 wherein the extraction solution of the group VIII metal Ml used in the extraction step comprises a polar protic solvent, preferably selected from the group formed by methanol, ethanol, and water, or alternatively a mixture of water-ethanol, water-methanol or water-citric acid.

8. A process according to any one of the preceding claims, wherein said process comprises at least one step of treating the solution of extracted metal(s) before its use in the impregnation step, selected from at least one of the following treatments: purification (C), concentration (D), adjustment of the composition (E) of said solution, dilution.

9. A method according to any one of the preceding claims in which said impregnation step (F) is carried out by bringing said support into contact with an impregnation solution derived from said solution of metal / metals extracted preferably by one or more dry impregnation(s).

10. A process according to claim 9 wherein the step of impregnating the support is carried out from the solution of extracted metal(s) and a supplement of at least the metal of group VIII, the supplement being able to be either previously added to the solution of extracted metal(s) for a premix, or to be added separately from the solution of extracted metal(s).

11. A process according to claim 9 in which the support on which the impregnation step is carried out with the impregnation solution from the solution of metals / extracted metal(s) is pre-impregnated or post-impregnated with a so-called fresh or conventional impregnation solution, i.e. not produced by the process.

12. A process according to any one of the preceding claims wherein the support on which the impregnation is carried out with the impregnation solution from the extracted metal / metal(s) solution is calcined at very high temperature in order to form a spinel between the cobalt and the alumina of the support before the addition of the group VIII metal and preferably cobalt by impregnation of said impregnation solution.

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