Catalyst for reformate treatment, comprising copper, nickel and sulfur

Abstract

Catalyst comprising nickel, copper and sulfur, between 10% and 50% by weight of nickel element relative to the total weight of the catalyst, between 0.15% and 0.45% by weight of copper element relative to the total weight of the catalyst, and between 0.1 and 2% by weight of sulfur element relative to the total weight of the catalyst, and also comprising an alumina support.

Description

[0001] Catalyst containing copper, nickel, and sulfur for reconditioning treatment

[0002] Scope of the invention

[0003] The present invention relates to a nickel-copper supported catalyst particularly suited to the hydrogenation of unsaturated hydrocarbons, and more specifically, the selective hydrogenation of polyunsaturated compounds contained in reformate feedstocks. This invention is particularly relevant to the case of hydrocarbon fractions composed simultaneously of unsaturated or polyunsaturated species and aromatics, where the aim is to selectively hydrogenate the unsaturated or polyunsaturated compounds while minimizing the hydrogenation of the aromatic compounds.

[0004] State of the art

[0005] Selective hydrogenation catalysts for polyunsaturated compounds are generally based on metals from group VIII of the periodic table, such as nickel or palladium. The metal is in the form of nanometric metallic particles deposited on a support, which may be a refractory oxide.

[0006] It is often suggested that palladium be replaced by nickel, a less active metal than palladium, which therefore requires a larger quantity in the catalyst. Thus, nickel-based catalysts generally have a nickel content of between 5 and 50% by weight relative to the catalyst.

[0007] The promotion of nickel-based catalysts has frequently been proposed to improve performance in the hydrogenation of unsaturated hydrocarbons, particularly in selective hydrogenation. For example, US patent 5,208,405 discloses a nickel-silver-based catalyst for the selective hydrogenation of C4-C10 diolefins. Furthermore, it is known to promote nickel, which is the predominant component, with Group IB metals, especially gold (FR 2,949,077) or tin (FR 2,949,078). Document FR 3,011,844 discloses a catalyst for implementing a selective hydrogenation process comprising a support and an active metallic phase deposited on the support, the active metallic phase comprising copper and at least one nickel or cobalt metal in a Cu:(Ni and / or Co) molar ratio greater than 1.

[0008] Document W02021 / 018600 discloses a nickel-copper catalyst on an alumina support, comprising between 1 and 50% by weight of elemental nickel relative to the total weight of nickel, between 0.5 and 15% by weight of elemental copper relative to the total weight of nickel, at least some of the nickel and copper being in the form of a nickel-copper alloy, and a molar ratio of nickel to copper of between 0.5 and 5 mol / mol

[0009] Objects of the invention

[0010] Continuing its research in the field of hydrogenation of hydrocarbon feedstocks including polyunsaturated hydrocarbon compounds, the Applicant has surprisingly discovered that a nickel, copper and sulfur-based catalyst, with a very specific copper content and within a narrow range of values, makes it possible to obtain a significant improvement in terms of activity and selectivity in the selective hydrogenation of olefins contained in a reformate feedstock.

[0011] The present invention relates to a catalyst comprising nickel, copper and sulfur, with between 10% and 50% by weight of nickel relative to the total weight of the catalyst, between 0.15% and 0.45% by weight of copper relative to the total weight of the catalyst, and between 0.1% and 2% by weight of sulfur relative to the total weight of the catalyst, and a support comprising alumina.

[0012] According to one or more embodiments of the invention, the size of the nickel particles, measured in oxide form, is less than 6 nm.

[0013] According to one or more embodiments of the invention, the support for said catalyst is alumina.

[0014] According to one or more embodiments of the invention, the nickel content is between 13% and 27% as nickel element relative to the total weight of the catalyst.

[0015] According to one or more embodiments of the invention, the copper content is between 0.25% and 0.35% as elemental copper relative to the total weight of the catalyst.

[0016] According to one or more embodiments of the invention, the sulfur content is between 0.9% and 1.45% as a sulfur element relative to the total weight of the catalyst.

[0017] According to one or more embodiments of the invention, the support has a specific surface area of ​​between 10 and 220 m² 2 / g.

[0018] Another object according to the invention relates to a process for preparing the catalyst according to one of the invention comprising at least the following steps: a) the following sub-steps are carried out in sequence: a1) a solution comprising at least one nickel precursor and at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function are brought into contact with the alumina support to obtain a catalyst precursor; a2) the catalyst precursor obtained at the end of step a1) is dried at a temperature below 250°C; a3) the dried catalyst precursor obtained at the end of step a2) is calcined at a temperature between 250°C and 600°C;b) the following sub-steps are carried out in sequence: b1) the alumina support is contacted with at least one solution containing at least one copper precursor and one nickel precursor; b2) the catalyst precursor obtained at the end of step b1 is dried at least once at a temperature below 250°C; b3) the dried catalyst precursor obtained at the end of step b2 is calcined at a temperature between 250°C and 600°C; steps a) and b) being carried out separately in any order; (c) a reduction step in the presence of hydrogen of the catalyst precursor obtained at the end of steps (a) and (b), or (b) and (a), at a temperature greater than or equal to 90°C and less than or equal to 500°C, for a duration of between 5 minutes and 4 hours, and with a hydrogen flow rate, expressed in NL / hour / gram of catalyst, of between 0.01 and 100 NL / hour / gram of catalyst; (d) a sulfidation step in the presence of a sulfur compound.

[0019] According to one or more embodiments of the invention, step a) is carried out followed by step b).

[0020] According to one or more embodiments of the invention, step a) is carried out twice successively, before or after the implementation of step b).

[0021] According to one or more embodiments of the invention, the sulfur compound is chosen from the following compounds: thiophene, thiophane, dimethyl disulfide, dimethyl sulfide, diethyl sulfide, dipropyl sulfide, propylmethyl sulfide, di-thio-di-ethanol, di-tert-butyl polysulfides, di-tert-nonyl polysulfides.

[0022] According to one or more embodiments of the invention, the molar ratio between nickel and copper supplied in substep b1) is between 0.5 and 3 mol / mol. According to one or more embodiments of the invention, step c) of reduction is carried out first, followed by step d) of sulfidation.

[0023] According to one or more embodiments of the invention, the organic compound of substep a1) is selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, levulinic acid, ethylene glycol, propane-1,3-diol, butane-1,4-diol, glycerol, xylitol, mannitol, sorbitol, diethylene glycol, glucose, gamma-valerolactone, dimethyl carbonate, diethyl carbonate, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylmethanamide, 2-pyrrolidone, γ-lactam, lactamide, urea, alanine, arginine, lysine, the proline, serine, EDTA.

[0024] Another object of the invention relates to a process for the selective hydrogenation of olefins contained in a catalytic reformate feed comprising between 3 and 11 carbon atoms per olefin, which process being carried out at a temperature between 20°C and 300°C, at a pressure between 0.1 MPa and 6.0 MPa, at a volumetric rate of between 1 and 100°C. -1 and 100 hours -1 , at a molar ratio hydrogen / (olefins to be hydrogenated) between 0.5 and 1000, in the presence of a catalyst according to the invention, or obtained according to the preparation process according to the invention.

[0025] Detailed description

[0026] 1. Definitions

[0027] In the following detailed description, many specific details are presented to provide a more thorough understanding of the process. However, it will be apparent to those skilled in the art that the process can be implemented without necessarily including all of these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0028] It is specified that, throughout this description, the expression "between ... and ..." should be understood as including the cited limits, unless otherwise specified.

[0029] In this description, the term "include" is synonymous with (means the same as) other elements not mentioned. It is understood that the term "include" includes the exclusive and closed term "consist".

[0030] In addition, when used in this description, the terms "essentially" or "substantially" or "approximately" in relation to a reference value correspond to an approximation of ± 10%, preferably ± 5%, very preferably ± 2%, or even more preferably ± 1% of that reference value, which may be a temperature, pressure, distance, speed, flow rate, content of compound(s), etc.

[0031] In the sense of the present invention, the different embodiments presented can be implemented separately or in combination with each other, without limitation of combinations when this is technically feasible.

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

[0033] In what follows, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII (or VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IIIPAC classification.

[0034] The BET specific surface area is measured by nitrogen physisorption. The BET specific surface area is measured by nitrogen physisorption according to ASTM D3663-03 as described in Rouquerol F.; Rouquerol J.; Singh K. "Adsorption by Powders & Porous Soils: Principle, methodology and applications", Academic Press, 1999.

[0035] The total pore volume is measured by mercury porosimetry according to ASTM D4284-92 with a wetting angle of 140°, for example using an Autopore® III model device from Microméritics®.

[0036] Nickel, copper, alkali element (such as potassium or sodium), and sulfur content are measured by X-ray fluorescence.

[0037] The term "nickel particle size" refers to the diameter of nickel crystallites in their oxide form. The diameter of nickel crystallites in their oxide form is determined by X-ray diffraction, from the width of the diffraction line located at the angle 2θ = 43° (i.e., along the crystallographic direction

[0200] ) using Scherrer's relation. This method, used in X-ray diffraction on polycrystalline powders or samples, which relates the full width at half maximum (FWHM) of the diffraction peaks to the particle size, is described in detail in the reference: Appl. Cryst. (1978), 11, 102-113, "Scherrer after sixty years: A survey and some new results in the determination of crystallite size," J.I. Langford and A.J.C. Wilson. According to the present invention, the term "olefin" refers to hydrocarbons comprising a double bond.The term "mono-olefin" refers to hydrocarbons containing one double bond, while the term di-olefin refers to hydrocarbons containing two double bonds.

[0038] By hydrocarbon Cn cut, we mean a cut comprising hydrocarbons with n carbon atoms.

[0039] A Cn+ cut is understood to be a cut comprising hydrocarbons with at least n carbon atoms.

[0040] By Cn- section we mean a section comprising hydrocarbons with at most n carbon atoms.

[0041] The hourly volumetric velocity "WH" refers to the volumetric flow rate of the feed at the reactor inlet in m³ 3 / h at 15°C, 0.1 MPa divided by the catalyst volume in m³ 3 content in the reactor.

[0042] By hourly volumetric velocity “PPH”, we mean the mass flow rate of the feed at the reactor inlet in kg / h at 15°C, 0.1MPa divided by the mass of catalyst in kg contained in the reactor.

[0043] In this description, pressures are expressed as relative values ​​unless otherwise specified.

[0044] 2. Catalyst

[0045] An object according to the invention relates to a catalyst comprising, preferably made of, nickel, copper and sulfur, between 10% and 50% by weight of nickel element relative to the total weight of the catalyst, between 0.15% and 0.45% by weight of copper element relative to the total weight of the catalyst, and between 0.1% and 2% by weight of sulfur element relative to the total weight of the catalyst and a support comprising, preferably made of, alumina.

[0046] The nickel content in said catalyst according to the invention is between 10% and 50% by weight in nickel element relative to the total weight of the catalyst, more preferably between 11% and 30% by weight and even more preferably between 12% and 28% by weight, and even more preferably between 13% and 27% by weight relative to the total weight of the catalyst.

[0047] The copper content is between 0.15% and 0.45% by weight as elemental copper relative to the total weight of the catalyst, preferably between 0.20% and 0.40% by weight, more preferably between 0.22% and 0.38% by weight, and even more preferably between 0.25% and 0.35% by weight. The catalyst also comprises sulfur, at a content of between 0.1% and 2% by weight as elemental sulfur, more preferably between 0.5% and 1.7% by weight, and even more preferably between 0.9% and 1.45% by weight relative to the total weight of the catalyst.

[0048] The size of nickel particles, measured in oxide form, in the catalyst is less than 6 nm, preferably less than 5 nm, more preferably less than 4 nm, and even more preferably less than 3 nm.

[0049] The specific surface area of ​​the catalyst is generally between 10 m 2 / g and 220 m 2 / g, preferably between 25 m 2 / g and 180 m 2 / g, preferably between 40 m 2 / g and 160 m 2 / g, and even more preferentially between 60 m 2 / g and 100 m 2 / g.

[0050] The total porous volume of the catalyst is generally between 0.1 and 1 ml / g, preferably between 0.2 ml / g and 0.8 ml / g, and particularly preferably between 0.3 ml / g and 0.7 ml / g.

[0051] The catalyst (and the support used for its preparation) is in the form of grains advantageously having a diameter between 0.5 mm and 10 mm. The grains may have any shape known to those skilled in the art, for example, spheres (preferably having a diameter between 1 mm and 8 mm), extrudates, tablets, or hollow cylinders. Preferably, the catalyst (and the support used for its preparation) is in the form of extrudates with a diameter between 0.5 mm and 10 mm, preferably between 0.8 mm and 3.2 mm, and most preferably between 1.0 mm and 2.5 mm, and a length between 0.5 mm and 20 mm. The "diameter" of the extrudates is understood to mean the diameter of the circle circumscribed about the cross-section of these extrudates. The catalyst may advantageously be in the form of cylindrical, multilobed, trilobed, or quadrilobed extrudates. Preferably its shape will be trilobed or quadrilobed.The shape of the lobes can be adjusted according to all methods known from the prior art.

[0052] 3. Support

[0053] The support includes alumina. Preferably, the support is made of alumina. Alumina generally has a crystallographic structure of the delta, gamma, or theta type, alone or in mixtures.

[0054] The characteristics of alumina mentioned in this section correspond to the characteristics of alumina before the support is brought into contact with the precursors of the catalyst's active phase, namely nickel and copper. In one embodiment according to the invention, the support is alumina, meaning that the support comprises at least 95%, preferably at least 98%, and most preferably at least 99% by weight of alumina relative to the weight of the support. The alumina generally has a crystallographic structure of the delta, gamma, or theta type, either alone or in mixtures.

[0055] In one embodiment according to the invention, the alumina support may include impurities such as metal oxides of groups HA, I II B, IVB, II B, II IA, IVA according to the CAS classification, preferably silica, titanium dioxide, zirconium dioxide, zinc oxide, magnesium oxide and calcium oxide, or alkali metals, preferably lithium, sodium or potassium, and / or alkaline earth metals, preferably magnesium, calcium, strontium or barium, or sulfur.

[0056] The specific surface area of ​​alumina is generally between 10 m 2 / g and 220 m 2 / g, preferably between 25 m 2 / g and 180 m 2 / g, preferably between 40 m 2 / g and 160 m 2 / g, and even more preferentially between 60 m 2 / g and 100 m 2 / g.

[0057] The pore volume of alumina is generally between 0.1 ml / g and 1 ml / g, preferably between 0.2 ml / g and 0.8 ml / g, and most preferably between 0.3 ml / g and 0.7 ml / g.

[0058] 4. Process for preparing the catalyst

[0059] An object according to the invention relates to a process for preparing the catalyst according to the invention comprising at least the following steps: a) the following sub-steps are carried out in sequence: a1) the alumina support is contacted with a solution comprising at least one nickel precursor and at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function to obtain a catalyst precursor; a2) the catalyst precursor obtained at the end of step a1) is dried at a temperature below 250°C; a3) the dried catalyst precursor obtained at the end of step a2) is calcined at a temperature between 250°C and 600°C; b) the following sub-steps are carried out in sequence: b1) the alumina support is contacted with at least one solution containing at least one copper precursor and one nickel precursor;b2) at least one drying step of the catalyst precursor obtained at the end of step b1) is carried out at a temperature below 250°C; b3) the dried catalyst precursor obtained at the end of step b2) is calcined at a temperature between 250°C and 600°C; steps a) and b) being carried out separately in any order; c) a reduction step in the presence of hydrogen of the catalyst precursor obtained at the end of steps a) and b), or b) and a), at a temperature greater than or equal to 90°C and less than or equal to 500°C, for a duration of between 5 minutes and 4 hours, and with a hydrogen flow rate, expressed in NL / hour / gram of catalyst, of between 0.01 and 100 NL / hour / gram of catalyst; d) a sulfidation step in the presence of a sulfur compound.

[0060] Steps a) and b) are described in detail below. Other optional steps are also described in the following section.

[0061] Sub-step a1)

[0062] The contacting of said support with at least one solution comprising at least one nickel precursor and at least one organic compound, as implemented in substep a1), can be carried out by impregnation, either dry or in excess, or by deposition-precipitation, according to methods well known to those skilled in the art. Indeed, it has been observed that catalysts according to the invention prepared in the presence of an organic compound (listed below) are more active than catalysts prepared in the absence of this type of organic compound. This effect is linked to the reduction in the size of the nickel particles.

[0063] Substep a1) is preferably carried out by impregnating the support, for example by contacting said support with at least one aqueous or organic solution (for example, methanol, ethanol, phenol, acetone, toluene, or dimethyl sulfoxide (DMSO)), or alternatively, a mixture of water and at least one organic solvent, containing at least one nickel precursor at least partially dissolved and at least one organic compound comprising at least one carboxylic acid, alcohol, ester, amide, or amine functional group. Preferably, the solution is aqueous. The pH of this solution may be modified by the optional addition of an acid or a base.

[0064] Preferably, said substep a1) is carried out by dry impregnation, which consists of bringing the catalyst support into contact with a solution, containing at least one nickel precursor and at least one organic compound, the volume of which is between 0.25 and 1.5 times the porous volume of the support to be impregnated.

[0065] When the nickel precursor is introduced in aqueous solution, advantageously a nickel precursor is used in the form of nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, sulfate, formate, complexes formed by a polyacid or an acid-alcohol and its salts, complexes formed with acetylacetonates, tetrammine or hexammine complexes, or any other inorganic derivative soluble in aqueous solution, which is brought into contact with said support.

[0066] Preferably, nickel nitrate, nickel hydroxide, nickel carbonate, nickel chloride, or nickel hydroxycarbonate are advantageously used as nickel precursors. Most preferably, the nickel precursor is nickel nitrate, nickel carbonate, or nickel hydroxide.

[0067] The quantities of nickel precursor(s) introduced into the solution are chosen in such a way that the total nickel content in the final catalyst (i.e. after the sequence of steps a) and b), or b) and a)) is between 10% and 50% by weight of nickel element relative to the total weight of the catalyst, more preferably between 11% and 30% by weight and even more preferably between 12% and 28% by weight, and even more preferably between 13% and 27% by weight relative to the total weight of the catalyst.

[0068] The said organic compound is preferably chosen from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, levulinic acid, ethylene glycol, propane-1,3-diol, butane-1,4-diol, glycerol, xylitol, mannitol, sorbitol, diethylene glycol, triethylene glycol, glucose, gamma valerolactone, dimethyl carbonate, diethyl carbonate, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylmethanamide, 2-pyrrolidone, y-lactam, lactamide, urea, alanine, arginine, lysine, proline, serine, EDTA. More preferably, the said organic compound is chosen from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, levulinic acid.Even more preferentially, the said organic compound is malonic acid.

[0069] Advantageously, the molar ratio between said organic compound and the element nickel also introduced in substep a1) is between 0.01 and 5.0 mol / mol, preferably between 0.05 and 2.0 mol / mol, more preferably between 0.1 and 1.5 mol / mol and even more preferably between 0.3 and 1.2 mol / mol.

[0070] Substep a2) Drying substep a2 is advantageously carried out at a temperature below 250°C, preferably between 15°C and 180°C, more preferably between 30°C and 160°C, even more preferably between 50°C and 150°C, and even more preferably between 70°C and 140°C, for a typical duration of between 0.5 hours and 12 hours, and even more preferably for a duration of between 0.5 hours and 5 hours. Longer durations are not excluded, but do not necessarily provide any improvement.

[0071] The drying stage can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere, an atmosphere containing oxygen, or a mixture of inert gases and oxygen. It is advantageously carried out at atmospheric pressure or reduced pressure. Preferably, this stage is carried out at atmospheric pressure and in the presence of air or nitrogen.

[0072] At the end of substep a2), the total, partial, or absence of the organic compound in the catalyst does not affect the activity and / or selectivity of the catalyst in the context of the hydrogenation of polyunsaturated compounds contained in reformates or in the hydrogenation of olefins in a middle distillate cut.

[0073] Sub-step a3)

[0074] Substep a3) of calcination can be carried out at a temperature between 250°C and 600°C, preferably between 350°C and 550°C, for a typical duration of 0.5 hours to 24 hours, preferably 0.5 hours to 12 hours, and even more preferably 0.5 hours to 10 hours, preferably under an inert atmosphere or an atmosphere containing oxygen. Longer durations are not excluded, but do not necessarily provide any improvement.

[0075] At the end of substep a3), the total, partial, or absence of organic compound in the catalyst does not affect the activity and / or selectivity of the catalyst in the context of the hydrogenation of polyunsaturated compounds contained in reformates or in the hydrogenation of olefins in a middle distillate cut.

[0076] Under

[0077] The contacting of said support with at least one solution comprising at least one nickel precursor and at least one copper precursor, in accordance with the implementation of substep b1), may be carried out by impregnation, either dry or in excess, or by deposition-precipitation, according to methods well known to those skilled in the art. Substep b1) is preferably carried out by impregnation of the catalyst precursor, consisting, for example, of contacting said support with at least one aqueous or organic solution (for example, methanol, ethanol, phenol, acetone, toluene, or dimethyl sulfoxide (DMSO)), or a solution consisting of a mixture of water and at least one organic solvent, comprising, preferably, at least one nickel precursor and at least one copper precursor, at least partially dissolved. Preferably, the solution is aqueous.The pH of this solution can be modified by the possible addition of an acid or a base.

[0078] Preferably, said substep b1) is carried out by dry impregnation, which consists of bringing the support of the catalyst precursor into contact with a solution, comprising, preferably made up of, at least one nickel precursor and at least one copper precursor, the volume of the solution of which is between 0.25 and 1.5 times the porous volume of the support to be impregnated.

[0079] When the nickel precursor is introduced into aqueous solution, advantageously a nickel precursor is used in the form of nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, sulfate, formate, complexes formed by a polyacid or an acid-alcohol and its salts, complexes formed with acetylacetonates, tetrammine or hexammine complexes, or any other inorganic derivative soluble in aqueous solution, which is brought into contact with said catalyst precursor. Preferably, nickel nitrate, nickel hydroxide, nickel carbonate, nickel chloride, or nickel hydroxycarbonate are advantageously used as nickel precursors. Most preferably, the nickel precursor is nickel nitrate, nickel carbonate, or nickel hydroxide.

[0080] When a copper precursor is introduced into aqueous solution, a copper precursor in mineral or organic form is advantageously used. In mineral form, the copper precursor can be chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide, or copper fluoride. Copper nitrate is the preferred precursor salt.

[0081] The quantities of nickel precursor(s) introduced into the solution are chosen in such a way that the total nickel content in the final catalyst (i.e. after the sequence of steps a) and b), or b) and a)) is between 10% and 50% by weight of nickel element relative to the total weight of the catalyst, more preferably between 11% and 30% by weight and even more preferably between 12% and 28% by weight, and even more preferably between 13% and 27% by weight relative to the total weight of the catalyst.Preferably, in substep b1), the quantities of nickel precursor(s) introduced into the solution supplied in substep b1) are chosen in such a way that they allow the final catalyst to have a nickel content of between 0.05% and 1% by weight in nickel element relative to the total weight of the catalyst, more preferably between 0.07% and 0.75% by weight and even more preferably between 0.09% and 0.6% by weight, and even more preferably between 0.1% and 0.5% by weight.

[0082] The quantities of the copper precursor(s) introduced into the solution according to substep b1) are chosen in such a way that the total copper content is between 0.15% and 0.45% by weight as elemental copper relative to the total weight of the catalyst, preferably between 0.20% and 0.40% by weight, preferably between 0.22% and 0.38% by weight, and even more preferably between 0.25% and 0.35% by weight.

[0083] Advantageously, the molar ratio between nickel and copper supplied at substep b1) is between 0.5 and 3 mol / mol, preferably between 0.7 and 2 mol / mol, more preferably between 0.8 and 1.5 mol / mol, and even more preferably between 0.9 and 1.1 mol / mol.

[0084] Under

[0085] Substep b2) of drying is advantageously carried out at a temperature below 250°C, preferably between 15°C and 180°C, more preferably between 30°C and 160°C, even more preferably between 50°C and 150°C, and even more preferably between 70°C and 140°C, for a typical duration of between 0.5 hours and 12 hours, and even more preferably for a duration of between 0.5 hours and 5 hours. Longer durations are not excluded, but do not necessarily provide any improvement.

[0086] The drying stage can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere, an atmosphere containing oxygen, or a mixture of inert gases and oxygen. It is advantageously carried out at atmospheric pressure or reduced pressure. Preferably, this stage is carried out at atmospheric pressure and in the presence of air or nitrogen.

[0087] Substep b3)

[0088] Substep b3) of calcination can be carried out at a temperature between 250°C and 600°C, preferably between 350°C and 550°C, for a typical duration of 0.5 hours to 24 hours, preferably 0.5 hours to 12 hours, and even more preferably 0.5 hours to 10 hours, preferably under an inert atmosphere or an atmosphere containing oxygen. Longer durations are not excluded, but do not necessarily provide any improvement.

[0089] Implementation of steps a) and b)

[0090] According to the invention, steps a) and b) and steps a) and c) are carried out separately in any order.

[0091] In a preferred embodiment, step a) is carried out before step b).

[0092] In an embodiment according to the invention, step a) is carried out twice successively, before or after the implementation of step b), preferably before step b). The sequence order of the steps is as follows: a), a), b) or b), a), a). Preferably, the sequence order is as follows: a), a), b).

[0093] Step c) Reduction

[0094] Prior to the use of the catalyst, advantageously at least one reduction treatment step c) is carried out in the presence of hydrogen after the sequence of steps a) and b), or b) and a), so as to obtain a catalyst comprising nickel at least partially in metallic form.

[0095] This treatment activates the catalyst and forms metallic particles, particularly zero-valent nickel. This reduction treatment can be carried out in-situ or ex-situ, that is, after or before loading the catalyst into the hydrogenation reactor.

[0096] Hydrogen can be used pure or in mixtures (for example, a hydrogen / nitrogen, hydrogen / argon, or hydrogen / methane mixture). When hydrogen is used in a mixture, all proportions are possible.

[0097] The said reducing treatment is carried out at a temperature greater than or equal to 90°C and less than or equal to 500°C, preferably between 120°C and 500°C, and even more preferably between 150°C and 475°C.

[0098] The duration of the reduction treatment is between 5 and 180 minutes, preferably between 30 and 150 minutes, and even more preferably between 1 and 130 minutes. The temperature rise to the desired reduction temperature is generally slow, for example, set between 0.1 and 20°C / min, preferably between 0.5 and 10°C / min. The hydrogen flow rate, expressed in NL / hour / gram of catalyst, is between 0.01 and 100 NL / hour / gram of catalyst, preferably between 0.05 and 10 NL / hour / gram of catalyst, and even more preferably between 0.1 and 5 NL / hour / gram of catalyst.

[0099] Step d) Sulfurization

[0100] Prior to its use in the catalytic reactor, the catalyst according to the invention undergoes a sulfidation step with a sulfur compound before or after the reduction treatment step c), or before or after the passivation step c1, if it is performed, or before or after the depassivation step e, if it is performed. This sulfidation step can be carried out ex-situ or in-situ. The sulfidation step is performed using methods known to those skilled in the art.

[0101] The sulfur treatment step improves catalyst selectivity and prevents thermal runaway during the start-up of new catalysts (known as "runaway" in English). Sulfur treatment generally involves irreversibly poisoning the most aggressive nickel active sites on the new catalyst with a sulfur compound, thereby reducing the catalyst's activity and increasing its selectivity. This sulfur treatment step is carried out using methods known to those skilled in the art, and in particular, for example, by implementing one of the methods described in patent documents EP0466567, US5153163, FR2676184, W02004 / 098774, and EP0707890.The sulfur compound is chosen, for example, from the following: thiophene, thiophane, disulfides such as dimethyl disulfide (DMDS), alkyl monosulfides such as dimethyl sulfide (DMS), diethyl sulfide, dipropyl sulfide, and propylmethyl sulfide, or an organic disulfide with the formula HO-R1-SS-R2-OH such as dithiodiethanol with the formula HO-C2H4-SS-C2H4-OH (often called DEODS), or di-tert-alkyl polysulfides such as di-tert-butyl polysulfides (also called TBPS) or di-tert-nonyl polysulfides (also called TBPS). Preferably, the sulfur compound is dimethyl sulfide.

[0102] The sulfurization step is advantageously carried out between 0°C and 50°C, preferably between 10°C and 40°C, and more particularly at ambient temperature, and for a duration of between 1 and 16 hours, preferably between 1 and 6 hours, and more preferably between 2 and 5 hours. This step is generally carried out by any suitable means known to those skilled in the art.

[0103] During this step, between 0.1 and 2% by weight of sulfur is advantageously incorporated into the catalyst, more preferably between 0.5 and 1.7% by weight, and even more preferably between 0.8 and 1.45% by weight relative to the total weight of the catalyst. 5. Purification of feedstocks from the reformate

[0104] The catalyst according to the invention can be used for the purification of feeds from the reformate, intended for the production of monocyclic aromatics (para-xylene).Indeed, the effluent produced by catalytic reforming, possibly mixed with other processes known to those skilled in the art providing monocyclic aromatics (steam cracker, thermal or catalytic pyrolysis of organic feedstocks, fluidized bed cracking process), these processes being operated in high severity mode to aim for maximum production of aromatics, always contains a certain quantity of olefins, or even traces of higher unsaturated types of styrenic, indenic or alkenyl aromatics, which, if not eliminated, will generate several problems such as oligomerization / polymerization and deposition (which can lead to clogging) in hot equipment such as the xylene reboiling column or on the catalysts for the transformation of aromatics (isomerization, alkylation, transalkylation, disprotonation).Traditionally, these unsaturated compounds act as coking agents, significantly shortening the cycle time of aromatic transformation processes. The usual processes for removing these unsaturated compounds involve earthing, typically at temperatures exceeding 100°C, and even exceeding 200°C. This process forces alkylation of monocyclic aromatics on the unsaturated compounds present and absorbs them onto the earthing surface. These earthings must be changed frequently to maintain high unsaturated transformation efficiency and result in a loss of aromatic rings. Therefore, another object of the invention relates to a process for hydrogenating olefins, possibly including higher unsaturated compounds such as styrenes, indenines, or aromatic alkenyls, contained in reformates. The catalyst according to the invention allows for the selective hydrogenation of olefins, possibly including higher unsaturated compounds, without affecting the aromatic compounds.The feedstocks for this hydrogenation process comprise 5 to 12 carbon atoms per molecule. For example, a typical feedstock will consist of 100 ppm by weight of styrene, 1% olefins, 80% aromatics, and 19% paraffins and other compounds including naphthenes, indenes, or other naphtheno-aromatic and diaromatic compounds. The molar ratio (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally between 0.5 and 1000, preferably between 0.7 and 400; the temperature is between 20°C and 300°C, preferably between 30°C and 280°C; the volumetric rate per hour (VPO) is generally between 1 and 1000. -1 and 100 hours -1 preferably between 5 a.m. -1 and 50 hours -1 and the pressure is generally between 0.1 MPa and 6.0 MPa, preferably between 0.2 MPa and 5.0 MPa.

[0105] The invention is illustrated by the following examples. Examples

[0106] For all the catalysts mentioned in the examples below, the support is an alumina A in the form of an extrudate with a specific surface area of ​​80 m². 2 / g, a pore volume of 0.7 mL / g and a median pore diameter of 12 nm.

[0107] Example 1: Preparation of an aqueous solution of Ni precursors

[0108] The aqueous solution S1 used for the preparation of catalysts A to D is prepared by dissolving 58 g of nickel nitrate (NiNCh, supplier Strem Chemicals®) and 14.35 g of malonic acid (CAS 141-82-2; supplier Fluka®) in 42 mL of distilled water. The solution is heated to 60°C to facilitate the dissolution of the nickel nitrate and is impregnated very quickly to prevent nickel precipitation. The molar ratio of additive to Ni is set at 0.4. This yields solution S1.

[0109] Example 2: Preparation of an aqueous solution of Ni-Cu precursors

[0110] The aqueous solution of Ni-Cu precursors (solution S2) used for preparing NiCu-containing catalysts is prepared by dissolving 14.5 g of nickel nitrate (NiNO₃, supplied by Strem Chemicals®) in 13 mL of distilled water. This yields a solution with a Ni concentration of 116.6 g per liter. The copper nitrate precursor is then added to achieve a Ni / Cu molar ratio of 1. This produces solution S2.

[0111] The solution S1 prepared in Example 1 is dry-impregnated onto 10 g of alumina A. The resulting solid is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The solution S1 is impregnated a second time onto this solid, which is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours.

[0112] Before in situ testing in the reactor, catalyst precursor A is reduced at 400°C for 4 h under a flow of H2 at 1 NL / h / gram of catalyst. The solid is then sulfided by contacting it with DMDS (dimethyl disulfide) at room temperature for 4 h to the final target sulfur content (see example 7 and [Table 1]).

[0113] Catalyst A is obtained, comprising 25% by weight of Ni and 0.65% by weight of sulfur relative to the total weight of the catalyst. Example 4: Catalyst B - 25% by weight of Ni + Ni-Cu precursors with 0.35% by weight of Cu and 0.37% by weight of Ni (Ni / Cu ratio=1) in post-impregnation (compliant).

[0114] The solution S1 prepared in Example 1 is dry-impregnated onto 10 g of alumina A. The resulting solid is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The solution S1 is impregnated a second time onto this solid, which is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours.

[0115] Solution S2 is impregnated onto catalyst precursor B1 to obtain a Ni / Cu ratio of 1 and 0.35 wt% Cu. This solid is then oven-dried overnight at 120°C, and then calcined under an air flow of 1 L / h / g of catalyst at 450°C for 2 hours.

[0116] Before in situ testing in the reactor, catalyst precursor B is reduced at 400°C for 2 h under a flow of H2 at 1 NL / h / gram of catalyst. The solid is then sulfided by contacting it with DMDS (dimethyl disulfide) at room temperature for 4 h to the final target sulfur content (see example 7 and [Table 1]).

[0117] Example 5: Catalyst C - 25% by weight of Ni + Ni-Cu precursors with 0.7% by weight of Cu, and 0.74% by weight of Ni (Ni / Cu ratio=1) in post-impregnation (non-compliant)

[0118] The solution S1 prepared in Example 1 is dry-impregnated onto 10 g of alumina A. The resulting solid is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The solution S1 is impregnated a second time onto this solid, which is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The calcined catalyst precursor thus prepared contains 25% by weight of nickel relative to the total weight of the catalyst supported on alumina. This yields the catalyst precursor C1.

[0119] Solution S2 is impregnated with catalyst precursor C1 to obtain a Ni / Cu ratio of 1 and 0.70 wt% Cu. This solid is then oven-dried overnight at 120°C, and then calcined under an air flow of 1 L / h / g of catalyst at 450°C for 2 hours.

[0120] Before in situ testing in the reactor, the catalyst precursor C is then reduced at 400°C for 2 h under a flow rate of 1 hL NL / h / gram of catalyst. The solid is then sulfided by contacting it with DMDS (dimethyl disulfide) at room temperature for 4 h to the final target sulfur content (see example 7 and [Table 1]).

[0121] Example 6: Catalyst D - 25% by weight of Ni + Ni-Cu precursors with 0.1% by weight of Cu, and 0.11% by weight of Ni (Ni / Cu ratio=1)

[0122] The solution S1 prepared in Example 1 is dry-impregnated onto 10 g of alumina A. The resulting solid is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The solution S1 is impregnated a second time onto this solid, which is then oven-dried overnight at 120°C and calcined under an airflow of 1 L / h / g of catalyst at 450°C for 2 hours. The calcined catalyst precursor thus prepared contains 25% by weight of nickel relative to the total weight of the catalyst supported on alumina. This yields the catalyst precursor D1.

[0123] Solution S2 is impregnated onto catalyst precursor D1 to obtain a Ni / Cu ratio of 1 and 0.10 wt% Cu. This solid is then oven-dried overnight at 120°C, and then calcined under an air flow of 1 L / h / g of catalyst at 450°C for 2 hours.

[0124] Before in-situ testing in the reactor, the catalyst precursor D is reduced at 400°C for 2 h under a flow rate of 1 hL NL / h / gram of catalyst. The solid is then sulfided by contacting it with DM DS (dimethyl disulfide) at room temperature for 4 h to the final target sulfur content (see Example 7 and [Table 1]). of a mixture containing olefins and

[0125] In this example, a synthetic feedstock representative of a real-world feedstock is used, comprising a commercial technical blend of diisobutene (DIB, a mixture of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, Sigma Aldrich, CAS: 25167-70-8) as the olefinic compounds and nitriding-grade toluene as the aromatic compound. A mixture of these two products is prepared (37 g of diisobutene per 200 mL of toluene). This feedstock is contacted in a 2 MPa flow-through bed reactor heated to 80°C, for each of the catalysts A to D, previously reduced to 450°C for different durations (see [Table 1]), under a flow of pure hydrogen (1 NL of hydrogen per gram of catalyst). Each reduced catalyst A to D is then sulfided by contacting DM DS (dimethyl disulfide) at room temperature for 4 hours to the final target sulfur content (see [Table 1]).The performance of different catalysts is compared by monitoring, on the one hand, the conversion of olefins present in the diisobutene mixture over time, via successive liquid samples analyzed by gas chromatography, and on the other hand, the conversion of toluene to methylcyclohexane. A first-order kinetic model is fitted to the conversion of the bulk olefins, and a zero-order kinetic model (with toluene in large excess) is fitted to monitor the hydrogenation of toluene. The ratio between the hydrogenation rate constant of the olefins and that of the toluene provides a ranking of the catalysts in terms of selectivity. The larger the ratio, the more the catalysts are favored for a high rate of olefin hydrogenation and a slow rate of aromatic hydrogenation. Both the hydrogenation rate constant of the olefins and the selectivity ratio are presented.We will seek to have a high olefin conversion kinetic constant as well as a high selectivity ratio to classify the catalysts of interest.

[0126] Table 1 In Table 1 above, the activity of catalyst A reduced at 450°C for 4 hours serves as a baseline for evaluating the activity of the other catalysts used in the hydrogenation reaction. It can be seen that the addition of 0.35% by weight of Ou (catalyst B) results in better performance for a reduction at 450°C for only 2 hours than for a reduction at 450°C for 4 hours. However, the addition of only 0.1% by weight of Cu (catalyst D) provides a slight improvement in performance, but still less than that obtained for a reduction at 450°C for 2 hours (catalyst B). Finally, an excessive addition of Cu (catalyst C) results in better activity but at the expense of selectivity, as the olefin-to-aromatic ratio is drastically reduced.Indeed, from a certain amount of copper supplied to the catalyst, the copper seems to sulfide preferentially at the expense of nickel, which leads to excessive hydrogenation of aromatic compounds.

Claims

DEMANDS 1. Catalyst comprising nickel, copper and sulfur, between 10% and 50% by weight of nickel element relative to the total weight of the catalyst, between 0.15% and 0.45% by weight of copper element relative to the total weight of the catalyst, and between 0.1% and 2% by weight of sulfur element relative to the total weight of the catalyst and a support comprising alumina.

2. Catalyst according to claim 1, characterized in that the size of the nickel particles, measured in oxide form, is less than 6 nm.

3. Catalyst according to any one of the preceding claims, characterized in that the nickel content is between 13% and 27% in element nickel relative to the total weight of the catalyst.

4. Catalyst according to any one of the preceding claims, characterized in that the copper content is between 0.25% and 0.35% in elemental copper relative to the total weight of the catalyst.

5. Catalyst according to any one of the preceding claims, characterized in that the sulfur content is between 0.9% and 1.45% as element sulfur relative to the total weight of the catalyst.

6. Catalyst according to any one of the preceding claims, characterized in that the support has a specific surface area between 10 and 220 m² 2 / g.

7. A process for preparing the catalyst according to any one of the preceding claims comprising at least the following steps: a) the following substeps are carried out in sequence: a1) the alumina support is contacted with a solution comprising at least one nickel precursor and at least one organic compound comprising at least one carboxylic acid function, or at least one alcohol function, or at least one ester function, or at least one amide function, or at least one amine function to obtain a catalyst precursor; a2) the catalyst precursor obtained at the end of step a1) is dried at a temperature below 250°C; a3) the dried catalyst precursor obtained at the end of step a2) is calcined at a temperature between 250°C and 600°C; b) the following substeps are carried out in sequence: b1) the alumina support is contacted with at least one solution containing at least one copper precursor and one nickel precursor; b2) at least one drying step of the catalyst precursor obtained at the end of step b1) is carried out at a temperature below 250°C; b3) the dried catalyst precursor obtained at the end of step b2) is calcined at a temperature between 250°C and 600°C; steps a) and b) being carried out separately in any order; c) a reduction step in the presence of hydrogen of the catalyst precursor obtained at the end of steps a) and b), or b) and a), at a temperature greater than or equal to 90°C and less than or equal to 500°C, for a duration of between 5 minutes and 4 hours, and with a hydrogen flow rate, expressed in NL / hour / gram of catalyst, of between 0.01 and 100 NL / hour / gram of catalyst; d) a sulfidation step in the presence of a sulfur compound.

8. Method according to the preceding claim, wherein step a) is carried out and then step b).

9. A method according to any one of claims 7 or 8, wherein step a) is carried out twice successively, before or after the implementation of step b).

10. A process according to any one of claims 7 to 9, wherein the sulfur compound is selected from the following compounds: thiophene, thiophane, dimethyl disulfide, dimethyl sulfide, diethyl sulfide, dipropyl sulfide, propylmethyl sulfide, di-thio-di-ethanol, di-tert-butyl polysulfides, di-tert-nonyl polysulfides.

11. A process according to any one of claims 7 to 10, wherein the molar ratio of nickel to copper supplied in substep b1) is between 0.5 and 3 mol / mol.

12. A process according to any one of claims 7 to 11, wherein step c) of reduction is carried out first and then step d) of sulfidation is carried out.

13. A process according to any one of claims 7 to 12, wherein the organic compound of substep a1) is selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, levulinic acid, ethylene glycol, triethylene glycol, propane-1,3-diol, butane-1,4-diol, glycerol, xylitol, mannitol, sorbitol, diethylene glycol, glucose, gamma-valerolactone, dimethyl carbonate, diethyl carbonate, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylmethanamide, 2-pyrrolidone, γ-lactam, lactamide, urea, alanine, arginine, lysine, proline, serine, EDTA.

14. A process for the selective hydrogenation of olefins contained in a catalytic reformate feed comprising between 3 and 11 carbon atoms per olefin, which process is carried out at a temperature between 20°C and 300°C, at a pressure between 0.1 MPa and 6.0 MPa, and at a volumetric rate per hour between 1 h -1 and 100 hours -1 , at a molar ratio hydrogen / (olefins to be hydrogenated) of between 0.5 and 1000, in the presence of a catalyst according to any one of claims 1 to 6, or obtained according to the preparation process according to any one of claims 7 to 13.

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