A catalyst comprising an active nickel phase in the form of small particles and a nickel-copper alloy.

Abstract

Disclosed is a catalyst comprising nickel and copper, specifically 1 to 50 wt. % elemental nickel relative to the total weight of the catalyst, and 0.5 to 15 wt. % elemental copper catalyst relative to the total weight of the catalyst, and an alumina support, wherein the catalyst is characterized in that: - the molar ratio of nickel to copper is 0.5 to 5 mol / mol; - at least a portion of the nickel and copper is in the form of a nickel-copper alloy; - the nickel content in the nickel-copper alloy is 0.5 to 15 wt. % by weight of elemental nickel relative to the total weight of the catalyst; and - the size of the nickel particles in the catalyst is less than 7 nm.

Description

[Technical field]

[0001] The present invention relates to supported metal catalysts based on nickel and copper that are particularly intended for the hydrogenation of unsaturated hydrocarbons, and more particularly for the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatic compounds. [Background technology]

[0002] Catalysts for the hydrogenation of aromatic compounds are generally based on a metal from group VIII of the periodic table of elements, for example nickel. The metal is in the form of nanoscale metal particles deposited on a support, which may be a refractory oxide. The content of metal from group VIII, the presence of an optional second metal element, the size of the metal particles and the distribution of the active phase in the support, and also the nature and pore distribution of the support, are parameters that may have an influence on the performance of the catalyst.

[0003] The rate of the hydrogenation reaction is governed by several criteria, such as the diffusion of reactants towards the surface of the catalyst (external diffusion limitation), the diffusion of reactants towards the active sites in the porosity of the support (internal diffusion limitation) and the intrinsic properties of the active phase, such as the size of the metal particles and the distribution of the active phase within the support.

[0004] To improve the performance level in the hydrogenation of unsaturated hydrocarbons, the promotion of nickel-based catalysts has often been proposed. By way of illustration, US Pat. No. 5,399,433 discloses a nickel and silver-based catalyst for the selective hydrogenation of C4-C10 diolefins. Furthermore, it is known to promote the predominantly present nickel with a group IB metal, in particular with gold (US Pat. No. 5,399,433) or tin (US Pat. No. 5,399,433). In the document (US Pat. No. 5,399,433), a catalyst for the implementation of a selective hydrogenation process is disclosed, which comprises a support and an active metal phase deposited on the support, the active metal phase comprising copper and at least one nickel or cobalt metal in a Cu:(Ni and / or Co) molar ratio greater than 1.

[0005] Furthermore, prior to the adoption of such a catalyst and its use in a hydrogenation process, a step of reduction treatment in the presence of a reducing gas is carried out to obtain a catalyst containing the active phase at least partially in metallic form. This treatment makes it possible to activate the catalyst and to form the metal particles. This treatment can be carried out in situ or ex situ, i.e. before or after the catalyst is loaded into the hydrogenation reactor.

[0006] Finally, it is known in the prior art to use additives of organic compound type for the preparation of metal catalysts for the selective hydrogenation or hydrogenation of aromatic compounds, with the aim of obtaining better catalytic performance, in particular better selectivity and / or activity. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 5,208,405 [Patent Document 2] French Patent Application Publication No. 2949077 (JP 2011-36857 A) [Patent Document 3] French Patent Application Publication No. 2949078 (JP 2011-36858 A) [Patent Document 4] French Patent Application Publication No. 3011844 Summary of the Invention [Means for solving the problem]

[0008] (Objective of the Invention) Continuing its research in the field of hydrogenation catalysts, the applicant has now discovered that it is possible to prepare catalysts that are particularly active and particularly selective in the selective hydrogenation of polyunsaturated compounds and also in the hydrogenation of aromatic compounds by contacting, in a specific sequence, at least one specific organic compound with a specific Cu:Ni ratio on a porous support and by carrying out these contacting steps followed by a step of reduction in the presence of a reducing gas in a contact reactor at a temperature below 200° C. Without wishing to be bound by any theory, it was observed by the applicant during the preparation of the catalyst that the presence of copper significantly improves the reducing power of nickel on the support, which makes it possible to carry out the step of reducing the metallic element in the presence of a reducing gas at lower temperatures and in shorter reaction times than those generally used in the prior art. By using less severe operating conditions than in the prior art, it is possible to carry out the reduction step directly in the reactor in which it is desired to carry out the hydrogenation of unsaturated or aromatic compounds.

[0009] Moreover, the Applicant has observed that during the preparation of the catalyst, a step of contacting the support with at least one solution simultaneously containing copper-based and nickel-based metal precursors, followed by a final drying and reduction step at low temperatures (150°C to 230°C) in the presence of a reducing gas, makes it possible to obtain a nickel-copper alloy (in reduced form), which, unexpectedly, makes it possible to significantly improve the reducing power of the nickel active phase on the support. Furthermore, the presence of copper in the catalyst makes it possible to maintain a good activity and a longer service life of the catalyst when it is placed in contact with a sulfur-containing hydrocarbon feedstock, in particular an aromatic hydrocarbon fraction. Indeed, compared to nickel, the copper present in the catalyst more easily captures the sulfur-containing compounds contained in the feedstock, which limits the irreversible poisoning of the active sites.

[0010] It has further been observed that catalysts according to the invention prepared in the presence of organic compounds (cited below) are much more active than catalysts prepared in the absence of organic compounds of this type.

[0011] The relative synergy obtained in this preparation process makes it possible to obtain catalysts containing nickel with a small particle size, which are particularly active, reducible at low temperatures and which are particularly selective in the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatic compounds.

[0012] A first subject of the invention relates to a catalyst comprising nickel and copper, with the nickel element in a proportion of 1% to 50% by weight relative to the total weight of the catalyst and the copper element in a proportion of 0.5% to 15% by weight relative to the total weight of the catalyst, comprising an alumina support, said catalyst comprising: - the molar ratio between nickel and copper is 0.5-5 mol / mol; - at least a portion of the nickel and copper is in the form of a nickel-copper alloy; - the nickel content in the nickel-copper alloy is between 0.5% and 15% by weight of elemental nickel relative to the total weight of the catalyst; - The size of nickel particles in the catalyst is less than 7 nm It is characterized by:

[0013] Advantageously, the size of the nickel particles in the catalyst is less than 5 nm.

[0014] Advantageously, the support is in the form of extrudates having a mean diameter between 0.5 and 10 mm.

[0015] Advantageously, the support is in the form of trilobal or tetralobal extrudates.

[0016] Another subject of the invention relates to a method for preparing a catalyst according to the invention, said method comprising the following steps: a) contacting an alumina support with at least one solution containing at least one nickel precursor; b) contacting the alumina support with at least one solution containing at least one nickel precursor and at least one copper precursor; c) contacting the alumina support with at least one solution containing at least one organic compound containing at least one carboxylic acid group, or at least one alcohol group, or at least one ester group, or at least one amide group, or at least one amine group; It is understood that: - steps a), b) and c) are carried out separately and in any order, or - steps a) and c) are carried out simultaneously and step b) is carried out before or after the combination of steps a) and c); - steps b) and c) are carried out simultaneously, with step a) being carried out before or after the combination of steps b) and c); d) carrying out at least one step of drying the catalyst precursor obtained at the end of steps a) to c) at a temperature below 250° C.; e) reducing the catalyst precursor obtained at the end of step d) by contacting said precursor with a reducing gas at a temperature of ≧150° C. and ≦250° C. Contains:

[0017] Advantageously, the molar ratio between said organic compound introduced in step c) and elemental nickel also introduced in step a) is between 0.01 and 5.0 mol / mol.

[0018] Advantageously, the organic compound of step c) is 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, glycol, glucose, 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.

[0019] Advantageously, step e) is carried out at a temperature comprised between 130°C and 190°C.

[0020] Advantageously, step e) is carried out for a period between 10 and 110 minutes.

[0021] Advantageously, the copper content is between 0.5% and 12% by weight of elemental copper relative to the total weight of the catalyst.

[0022] Advantageously, the copper precursor is chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride. Preferably, the copper precursor is copper nitrate.

[0023] Another subject of the invention relates to a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, contained in a hydrocarbon feedstock having a final boiling point below 300° C., which is carried out in the presence of a catalyst according to the invention, the temperature being between 0° C. and 300° C., the pressure being between 0.1 and 10 MPa, the hydrogen / polyunsaturated compound to be hydrogenated molar ratio being between 0.1 and 10, if the process is carried out in the liquid phase, and the hourly space velocity being between 0.1 and 200 h -1 or, if the process is carried out in the gas phase, the hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio is 0.5 to 1000, and the hourly space velocity is 100 to 40,000 h -1 It is.

[0024] Another subject of the invention relates to a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point below 650 ° C, which is carried out in the gas or liquid phase in the presence of a catalyst according to the invention, at a temperature between 30 ° C and 350 ° C, at a pressure between 0.1 and 20 MPa, at a hydrogen / aromatic compound molar ratio between 0.1 and 10, and at a space velocity HSV between 0.05 and 50 h -1 It is. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Detailed Description of the Invention (1.Definition) Hereinafter, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, 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.

[0026] The degree of reduction (DR) of the metal M contained in the catalyst is defined as the percentage of the reduced metal M after the step of reducing the catalyst. The degree of reduction (DR) corresponds to the ratio between the amount of reduced metal (M1) and the amount of theoretically reducible metal present on the catalyst measured by X-ray fluorescence, i.e. DR (%) = (M1 / M2) x 100. In the context of the present invention, the degree of reduction of nickel (Ni) was measured by X-ray diffraction (XRD) analysis. A description of the method for measuring the amount of reducible metal on an oxide catalyst is given later in this specification (see the Examples section).

[0027] The expression "specific surface area" of the catalyst according to the invention or of the support used for the preparation of said catalyst is intended to mean the BET specific surface area determined by nitrogen adsorption according to standard ASTM D 3663-78, which is derived from the Brunauer-Emmett-Teller method described in the journal "The Journal of the American Chemical Society", 60, 309 (1938).

[0028] In this application, the term "to comprise" is synonymous with (means the same as) "to include" and "to contain" and is inclusive or open and does not exclude other elements. The term "to comprise" is understood to encompass the exclusive and closed term "to consist of."

[0029] The term "macropores" is intended to mean pores with an opening greater than 50 nm.

[0030] The term "mesopores" is intended to mean pores with openings between 2 nm and 50 nm, both limits included.

[0031] The term "micropores" is intended to mean pores with openings smaller than 2 nm.

[0032] The term "total pore volume" of the catalyst according to the invention or of the support used for the preparation of said catalyst is intended to mean the volume measured by intrusion with a mercury porosimeter according to standard ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa) with a surface tension of 484 dyne / cm and a contact angle of 140°. The wetting angle was taken to be equal to 140° according to the recommendation in the work "Techniques de l'ingenieur, traite analyse et caracterisation" written by Jean Charpin and Bernard Rasneur, pages 1050-1055.

[0033] For better accuracy, the value of the total pore volume corresponds to the value of the total pore volume measured by mercury porosimetry intrusion measured on a sample minus the value of the total pore volume measured by mercury porosimetry intrusion measured on the same sample at a pressure corresponding to 30 psi (about 0.2 MPa).

[0034] The macropore and mesopore volumes are measured by mercury intrusion porosimetry according to standard ASTM D4284-83, with a maximum pressure of 4000 bar (400 MPa) using a surface tension of 484 dyne / cm and a contact angle of 140°. The value at which mercury fills all interparticle voids is set to 0.2 MPa, above which mercury is considered to penetrate into the pores of the sample.

[0035] The macropore volume of the catalyst according to the invention or of the support used for the preparation of said catalyst is defined as the cumulative volume of mercury introduced at a pressure between 0.2 MPa and 30 MPa and corresponds to the volume present in pores with an apparent diameter of more than 50 nm.

[0036] The mesopore volume of the catalyst according to the invention or of the support used for the preparation of said catalyst is defined as the cumulative volume of mercury introduced at a pressure of 30 MPa to 400 MPa and corresponds to the volume present in pores having an apparent diameter of 2 to 50 nm.

[0037] The micropore volume is measured by nitrogen porosimetry. The quantitative analysis of the microporosity is carried out using the "t" method (Lippens-De Boer method, 1965), which corresponds to the transformation of the starting adsorption isotherm, as described in the monograph "Adsorption by powders and porous solids. Principles, methodology and applications" by F. Rouquerol, J. Rouquerol and K. Sing, Academic Press, 1999.

[0038] The median mesopore diameter is also defined as the diameter such that, among the combined pores making up the mesopore volume, all pores having a size less than this diameter make up 50% of the total mesopore volume as determined by mercury porosimetry intrusion.

[0039] The median macropore diameter is also defined as the diameter such that, among the combined pores making up the macropore volume, all pores having a size less than this diameter make up 50% of the total macropore volume as determined by mercury porosimetry intrusion.

[0040] "Size of nickel particles" is understood to mean the diameter of nickel crystallites in the form of oxide. The diameter of nickel crystallites in the form of oxide 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 the Scherrer relation. This method, used in X-ray diffraction on polycrystalline samples or powders, connects the full width at half maximum of the diffraction peak to the size of the particles, and is described in detail in the following reference: Appl. Cryst. (1978), 11, 102-113, "Scherrer after sixty years: A survey and some new results in the determination of crystallite size", JI Langford and AJC Wilson.

[0041] The nickel and copper content is measured by X-ray fluorescence.

[0042] (2. Description) (catalyst) The present invention relates to a catalyst comprising nickel and copper, with a proportion of elemental nickel between 1% and 50% by weight relative to the total weight of the catalyst, and a proportion of elemental copper between 0.5% and 15% by weight relative to the total weight of the catalyst, and comprising an alumina support, said catalyst being characterized in that: the molar ratio between nickel and copper is between 0.5 and 5 mol / mol, preferably between 0.7 and 4.5 mol / mol and more preferentially between 0.9 and 4 mol / mol; at least a portion of the nickel and copper is in the form of a nickel-copper alloy, advantageously of the formula Ni x Cu y , where x is between 0.1 and 0.9 and y is between 0.1 and 0.9; the nickel content contained in the nickel-copper alloy is between 0.5% and 15% by weight, preferably between 1% and 12% by weight and more preferentially between 1% and 10% by weight, of elemental nickel relative to the total weight of the catalyst; the size of the nickel particles, measured in the oxide form, in the catalyst is less than 7 nm, preferably less than 5 nm, more preferentially less than 4 nm and even more preferentially less than 3 nm;

[0043] The nickel content in the catalyst according to the invention is advantageously between 1% and 50% by weight relative to the total weight of the catalyst, more preferentially between 2% and 40% by weight relative to the total weight of the catalyst, more preferentially between 3% and 35% by weight relative to the total weight of the catalyst and more preferentially between 5% and 25% by weight relative to the total weight of the catalyst.

[0044] The copper content is 0.5% to 15% by weight, preferably 0.5% to 12% by weight, preferably 0.75% to 10% by weight, and more preferably 1% to 9% by weight, of elemental copper relative to the total weight of the catalyst.

[0045] The nickel content in the nickel-copper alloy is advantageously between 0.5% and 15% by weight, preferably between 1% and 12% by weight and more preferentially between 1% and 10% by weight of elemental nickel relative to the total weight of the catalyst.

[0046] The molar ratio between nickel and copper is between 0.5 and 5 mol / mol, preferably between 0.7 and 4.5 mol / mol and more preferentially between 0.9 and 4 mol / mol.

[0047] The active phase of the catalyst does not contain any metal from group VIB, in particular it does not contain molybdenum or tungsten.

[0048] Said catalyst is generally presented in any form known to the person skilled in the art, for example in the form of beads (generally having a diameter between 1 and 8 mm), in the form of extrudates, in the form of tablets or in the form of hollow cylinders. Preferably, it consists of extrudates having a diameter generally between 0.5 and 10 mm, preferably between 0.8 and 3.2 mm, highly preferably between 1.0 and 2.5 mm, and an average length between 0.5 and 20 mm. The "mean diameter" of the extrudates is intended to mean the average diameter of the circle circumscribed in the cross section of these extrudates. The catalyst may advantageously be presented in the form of cylindrical, multilobal, trilobal or tetralobal extrudates. Preferably, its shape will be trilobal or tetralobal. The shape of the lobes may be adjusted by all methods known from the prior art.

[0049] The specific surface area of ​​a catalyst is generally 30 m 2 / g or more, preferably 50m 2 / g or more, more preferentially 60m 2 / g~500m 2 / g, and even more preferably 70m 2 / g~400m 2 / g.

[0050] The total pore volume of the catalyst is generally 0.1 to 1.5 cm 3 / g, preferably 0.35 to 1.2 cm 3 / g, preferentially 0.4 to 1.0 cm 3 / g, preferentially 0.45~0.9cm 3 / g.

[0051] The catalyst has a macropore volume advantageously less than or equal to 0.6 mL / g, preferably less than or equal to 0.5 mL / g, more preferentially less than or equal to 0.4 mL / g and even more preferentially less than or equal to 0.3 mL / g.

[0052] The mesopore volume of the catalyst is generally at least 0.10 mL / g, preferably at least 0.20 mL / g, preferably from 0.25 mL / g to 0.80 mL / g, more preferably from 0.30 to 0.65 mL / g.

[0053] The median diameter of the mesopores is advantageously between 3 nm and 25 nm, preferably between 6 and 20 nm, particularly preferably between 8 and 18 nm.

[0054] The median macropore diameter exhibited by the catalyst is advantageously between 50 and 1500 nm, preferably between 80 and 1000 nm and even more preferably between 250 and 800 nm.

[0055] Preferably, the catalyst exhibits low microporosity; highly preferably, it does not exhibit any microporosity.

[0056] (Carrier) According to the invention, the support is an alumina, i.e. it comprises at least 95% by weight, preferably at least 98% by weight, particularly preferably at least 99% by weight, of alumina relative to the weight of the support. The crystallographic structure which the alumina has is generally of the delta, gamma or theta alumina type, used alone or in mixtures.

[0057] According to the invention, the alumina support may also contain impurities, such as oxides of metals from groups IIA, IIIB, IVB, IIB, IIIA, IVA according to the CAS classification, preferably silica, titanium dioxide, zirconium dioxide, zinc oxide, magnesium oxide and calcium oxide, or else alkali metals, preferably lithium, sodium or potassium, and / or alkaline earth metals, preferably magnesium, calcium, strontium or barium, or else sulfur.

[0058] The specific surface area of ​​the carrier is generally 30 m 2 / g or more, preferably 50m 2 / g or more, more preferentially 60m 2 / g~500m 2 / g, preferentially 70m 2 / g~400m 2 / g. The BET specific surface area is measured by nitrogen physisorption.

[0059] The total pore volume of the support is generally 0.1 to 1.5 cm 3 / g, preferably 0.35 to 1.2 cm 3 / g, preferentially 0.4 to 1.0 cm 3 / g, preferentially 0.45~0.9cm 3 / g.

[0060] Methods for preparing the catalyst A subject of the present invention is also a process for preparing a catalyst according to the invention, said process comprising the following steps: a) contacting an alumina support with at least one solution containing at least one nickel precursor; b) contacting the alumina support with at least one solution containing at least one nickel precursor and at least one copper precursor; c) contacting the alumina support with at least one solution containing at least one organic compound containing at least one carboxylic acid group, or at least one alcohol group, or at least one ester group, or at least one amide group, or at least one amine group; It is understood that: - steps a), b) and c) are carried out separately and in any order, or - steps a) and c) are carried out simultaneously and step b) is carried out before or after the combination of steps a) and c); - steps b) and c) are carried out simultaneously, with step a) being carried out before or after the combination of steps b) and c); d) carrying out at least one step of drying the catalyst precursor obtained at the end of steps a) to c) at a temperature below 250° C.; e) reducing the catalyst precursor obtained at the end of step d) by contacting said precursor with a reducing gas at a temperature of ≧150° C. and ≦250° C. Contains:

[0061] The process steps for preparing the catalyst are described in detail below.

[0062] (Step a)--Contacting the support with a precursor of the nickel active phase) The deposition of nickel on said support may be carried out by carrying out step a), by dry impregnation or excess impregnation or else by deposition-precipitation, according to methods well known to those skilled in the art.

[0063] Said step i) is preferentially carried out by impregnation of the support, which consists, for example, of contacting said support with at least one solution containing a nickel precursor, which solution is aqueous or organic (for example methanol or ethanol or phenol or acetone or toluene or dimethylsulfoxide (DMSO)) or else consists of a mixture of water and at least one organic solvent and contains at least one nickel precursor at least partially dissolved, or else consists of contacting said support with at least one colloidal solution of at least one precursor of nickel in oxidized form (nickel oxide, oxy(hydroxide) or hydroxide nanoparticles) or in reduced form (metallic nanoparticles of nickel in reduced state). Preferably, the solution is aqueous. The pH of this solution could be modified by the optional addition of an acid or a base. According to another preferred variant, the aqueous solution is ammonia or ammonium NH4 + It may contain ions.

[0064] Preferably, said step a) is carried out by dry impregnation, which consists in contacting the support of the catalyst with a solution containing at least one nickel precursor, the volume of this solution being between 0.25 and 1.5 times the pore volume of the support to be impregnated.

[0065] When the nickel precursor is introduced into the aqueous solution, it is advantageous to use the nickel precursor in the form of a nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, sulfate or formate, in the form of a complex formed with a polyacid or with an acid alcohol and its salts, in the form of a complex formed with an acetylacetonate, in the form of a tetramine or hexamine complex or in the form of any other inorganic derivative soluble in aqueous solution, and brought into contact with said support.

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

[0067] The amount of nickel precursor(s) introduced into the solution is chosen so that the total content of nickel is between 1% and 50% by weight, preferably between 2% and 40% by weight, preferably between 3% and 35% by weight, and even more preferentially between 5 and 25% by weight, of said element relative to the total weight of the catalyst. In the embodiment in which step a) is carried out by dry impregnation or excess impregnation, preferably by dry impregnation, the impregnation of the support with nickel may advantageously be carried out via at least two impregnation cycles, with the same or different nickel precursors in each cycle. In this case, each impregnation may advantageously be followed by drying and optionally a heat treatment.

[0068] (Step b) Contacting the support with copper and nickel precursors) The deposition of nickel and copper on the alumina support may be carried out by dry impregnation or excess impregnation, or else by deposition-precipitation, according to methods well known to those skilled in the art.

[0069] Said step b) is preferentially carried out by impregnation of the catalyst precursor, which impregnation consists, for example, of contacting said support with at least one solution, aqueous or organic (for example methanol or ethanol or phenol or acetone or toluene or dimethylsulfoxide (DMSO)) or else of a mixture of water and at least one organic solvent, which comprises, and preferably consists of, at least one nickel precursor and at least one copper precursor at least partially dissolved, or else of contacting said catalyst precursor with at least one colloidal solution, which comprises, and preferably consists of, at least one nickel precursor and at least one copper precursor in oxidized form (nickel and copper oxide, oxy(hydroxide) or hydroxide nanoparticles) or in reduced form (nickel and copper metallic nanoparticles in reduced state). Preferably, the solution is aqueous. The pH of this solution may be modified by the optional addition of an acid or a base.

[0070] Preferably, said step b) is carried out by dry impregnation, which consists in contacting the catalyst precursor support with a solution containing, preferably consisting of, at least one nickel precursor and at least one copper precursor, the volume of which is between 0.25 and 1.5 times the pore volume of the support to be impregnated.

[0071] When the nickel precursor is introduced into the aqueous solution, it is advantageous to use a nickel precursor in the form of a nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, sulfate or formate, in the form of a complex formed with a polyacid or an acid alcohol and its salt, in the form of a complex formed with an acetylacetonate, in the form of a complex with tetramine or hexamine, or in the form of 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 precursor. Highly preferably, the nickel precursor is nickel nitrate, nickel carbonate or nickel hydroxide.

[0072] When the copper precursor is introduced into the aqueous solution, a copper precursor in mineral or organic form is advantageously used. In mineral form, the copper precursor may be selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride. Highly preferably, the copper precursor salt is copper nitrate.

[0073] According to the invention, the nickel precursor is provided in step e1) in the desired concentration so as to obtain, on the final catalyst (i.e. the catalyst obtained at the end of the reduction step e) or, if a passivation step f) is performed, a content of 0.5% to 10% by weight, preferably 0.5% to 8% by weight, more preferentially 1% to 7% by weight and even more preferentially 1% to 5% by weight, by weight of elemental nickel relative to the total weight of the final catalyst.

[0074] The amount of copper precursor(s) introduced into the solution according to step b) is chosen so that the total copper content is between 0.5% and 15% by weight, preferably between 0.5% and 12% by weight, preferably between 0.75% and 10% by weight and even more preferentially between 1% and 9% by weight, of elemental copper relative to the total weight of the final catalyst (i.e. the catalyst obtained at the end of reduction step e) or passivation step f) if a passivation step f) is performed).

[0075] (Step c) Contacting the support with an organic compound) The support may be contacted by any method known to those skilled in the art with at least one solution containing at least one organic compound comprising at least one carboxylic acid group, or at least one alcohol group, or at least one ester group, or at least one amide group, or at least one amine group, by carrying out said step c), since it has further been noted that the catalyst according to the invention prepared in the presence of an organic compound (as described above) is more active than the catalyst prepared in the absence of this type of organic compound. This effect is related to the reduction in the size of the nickel particles.

[0076] In particular, said step c) may be carried out by dry impregnation or by excess impregnation, according to methods known to those skilled in the art. Preferably, said step c) is carried out by dry impregnation, which consists in contacting the catalyst support with said solution in a volume between 0.25 and 1.5 times the pore volume of the support to be impregnated.

[0077] The solution containing at least one organic compound containing at least one carboxylic acid group, or at least one alcohol group, or at least one ester group, or at least one amide group, or at least one amine group, may be aqueous or organic (e.g. methanol or ethanol or phenol or acetone or toluene or dimethylsulfoxide (DMSO)) or else may consist of a mixture of water and at least one organic solvent. The organic compound is at least partially dissolved in the solution beforehand at the desired concentration. Preferably, the solution is aqueous or contains ethanol. Even more preferably, the solution is aqueous. The pH of the solution could be modified by optional addition of an acid or a base. In another possible embodiment, no solvent may be present in the impregnation solution.

[0078] In the embodiment in which step c) is carried out by dry impregnation or excess impregnation, preferably by dry impregnation, the impregnation of the support with at least one solution containing at least said organic compound may advantageously be carried out via at least two impregnation cycles, with the same or different organic compound in each cycle, where each impregnation is advantageously followed by drying and optionally a heat treatment.

[0079] Advantageously, the molar ratio of said organic compound introduced in step c) to elemental nickel also introduced in step a) is between 0.01 and 5.0 mol / mol, preferably between 0.05 and 2.0 mol / mol, more preferentially between 0.1 and 1.5 mol / mol and even more preferentially between 0.3 and 1.2 mol / mol.

[0080] The organic compound according to step c) may contain multiple, identical or different, carboxylic acid, alcohol, ester, amide or amine organic groups in the same molecule. The organic compound according to step c) may contain a combination of multiple types of organic groups selected from carboxylic acid, alcohol, ester, amide or amine organic groups.

[0081] (A) an organic compound containing at least one carboxylic acid group) In one embodiment according to the invention, the organic compound comprises at least one carboxylic acid group.

[0082] The organic compound containing at least one carboxylic acid group may be a saturated or unsaturated aliphatic organic compound or an aromatic organic compound. Preferably, the saturated or unsaturated aliphatic organic compound contains 1 to 9 carbon atoms, preferably 2 to 7 carbon atoms. Preferably, the aromatic organic compound contains 7 to 10 carbon atoms, preferably 7 to 9 carbon atoms.

[0083] The saturated or unsaturated aliphatic organic compound or the aromatic organic compound containing at least one carboxylic acid group may be selected from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids.

[0084] Advantageously, the organic compound comprising at least one carboxylic acid group is chosen from ethanedioic acid (oxalic acid), propanedioic acid (malonic acid), pentanedioic acid (glutaric acid), hydroxyacetic acid (glycolic acid), 2-hydroxypropanoic acid (lactic acid), 2-hydroxypropanedioic acid (tartronic acid), 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), 2,3-dihydroxybutanedioic acid (tartaric acid), 2-oxopropanoic acid (pyruvic acid) or 4-oxopentanoic acid (levulinic acid).

[0085] (B) an organic compound containing at least one alcohol group) In another embodiment according to the present invention, the organic compound comprises at least one alcohol group.

[0086] Preferably, said organic compound comprises from 2 to 20 carbon atoms, preferably from 2 to 12 carbon atoms, even more preferably from 2 to 8 carbon atoms.

[0087] Advantageously, the organic compound is chosen from methanol, ethanol, phenol, ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, glycerol, xylitol, mannitol, sorbitol, pyrocatechol, resorcinol, hydroquinone, diethylene glycol, triethylene glycol, polyethylene glycols with an average molar mass of less than 600 g / mol, glucose, mannose, fructose, sucrose, maltose or lactose, in any one of its isomeric forms.

[0088] (C) an organic compound containing at least one ester group In another embodiment according to the invention, the organic compound comprises at least one ester group. Preferably, said organic compound comprises from 2 to 20 carbon atoms, preferably from 3 to 14 carbon atoms, even more preferentially from 3 to 8 carbon atoms.

[0089] The organic compound may be chosen from linear or cyclic or unsaturated cyclic carboxylic acid esters, or cyclic or linear carbonate esters, or else linear carbonic acid diesters. In the case of cyclic carboxylic acid esters, the compound is γ-valerolactone.

[0090] In the case of a carboxylic acid unsaturated cyclic ester (containing unsaturation in the ring), the compound can be a furan or a pyrone or any one of their derivatives, for example 6-pentyl-α-pyrone.

[0091] In the case of linear carboxylic acid esters, the compound may be a compound containing a single ester group corresponding to the empirical formula RCOOR', where R and R' are linear, branched or cyclic alkyl groups, or alkyl groups containing unsaturation, or alkyl groups substituted by one or more aromatic rings, or aryl groups, each containing 1 to 15 carbon atoms, and may be the same or different. The R group may also be a hydrogen atom H. The organic compound is preferably methyl laurate.

[0092] In another embodiment according to the present invention, the organic compound may be a compound containing at least two carboxylic acid ester groups. Preferably, said compound is dimethyl succinate.

[0093] In another embodiment according to the present invention, the organic compound may be a compound containing at least one carboxylic acid ester group and at least one second functional group selected from an alcohol, an ether, a ketone or an aldehyde.

[0094] Preferably, the compound is dimethyl malate.

[0095] Advantageously, said organic compound comprises at least one carboxylic acid ester group and at least one ketone or aldehyde group. In the case of cyclic carbonates, the compound is propylene carbonate. In the case of linear carbonates, the compound is chosen from dimethyl carbonate, diethyl carbonate or diphenyl carbonate. In the case of linear carbonates, the compound is chosen from dimethyl dicarbonate, diethyl dicarbonate or di(tert-butyl) dicarbonate.

[0096] (D) An organic compound containing at least one amide group. In another embodiment according to the invention, the organic compound comprises at least one amide group selected from acyclic amide groups or cyclic amide groups which may contain alkyl, aryl or alkyl substituents containing unsaturation. The amide group may be selected from primary, secondary or tertiary amides.

[0097] Advantageously, the organic compound containing at least one amide group is chosen from formamide, N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylmethanamide, N,N-diethylacetamide, N,N-dimethylpropionamide, propanamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, γ-lactam, caprolactam, acetylleucine, N-acetylaspartic acid, aminohippuric acid, N-acetylglutamic acid, 4-acetamidobenzoic acid, lactamide and glycolamide, urea, N-methylurea, N,N′-dimethylurea, 1,1-dimethylurea and tetramethylurea, or any one of its isomers.

[0098] (E) an organic compound containing at least one amine group In another embodiment according to the invention, the organic compound comprises at least one amine group, said organic compound comprising from 1 to 20 carbon atoms, preferably from 1 to 14 carbon atoms, even more preferably from 2 to 8 carbon atoms.

[0099] In one embodiment according to the invention, the organic compound comprises at least one amine group and has the empirical formula C x N y H z where 1≦x≦20, 1≦y≦x, and 2≦z≦2x+2. More particularly, the organic compound is selected from ethylenediamine, diaminohexane, tetramethylenediamine, hexamethylenediamine, tetramethylethylenediamine, tetraethylethylenediamine, diethylenetriamine, and triethylenetetramine.

[0100] In one embodiment according to the invention, the organic compound comprises at least one amine group and at least one carboxylic acid group (amino acid). When the compound is an amino acid, it is preferably selected from alanine, arginine, lysine, proline, serine, threonine or EDTA.

[0101] In all of the above embodiments, the organic compound 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, proline, serine, and EDTA.

[0102] (Implementation of steps a), b) and c) According to the present invention: - steps a), b) and c) are carried out separately and in any order; or - steps a) and c) are carried out simultaneously and step b) is carried out before or after the combination of steps a) and c); - steps b) and c) are carried out simultaneously and step a) is carried out before or after the combination of steps b) and c).

[0103] In one preferred embodiment, step a) is performed, followed by steps b) and c) simultaneously.

[0104] In another preferred embodiment, steps a) and c) are carried out simultaneously, followed by step b).

[0105] (Step d) Drying the impregnated carrier) Step d) of drying the impregnated support is typically carried out at a temperature below 250° C., preferably between 15° C. and 180° C., more preferentially between 30° C. and 160° C., even more preferentially between 50° C. and 150° C., even more preferentially between 70° C. and 140° C., for a period typically between 10 minutes and 24 hours. Longer periods are not unconventional, but do not necessarily result in any improvement.

[0106] The drying step can be carried out by any technique known to the person skilled in the art. It is advantageously carried out under an inert atmosphere or under an oxygen-containing atmosphere or under a mixture of inert gas and oxygen. It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out in the presence of air or nitrogen at atmospheric pressure.

[0107] (Heat treatment of dried catalyst (optional step)) The dried catalyst precursor may undergo a further heat treatment step prior to the reduction step e) at temperatures between 250° C. and 1000° C., preferably between 250° C. and 750° C., typically for a period of 15 minutes to 10 hours, under an inert or oxygen-containing atmosphere, optionally in the presence of water. Longer treatment times are not unconventional but do not necessarily give an improvement.

[0108] The term "thermal treatment" is intended to mean a temperature treatment in the absence or presence of water, respectively. In the latter case, the contact with water vapor can be carried out at atmospheric pressure or under autogenous pressure. Multiple combined cycles can be carried out in the absence or presence of water. After this or these treatments, the catalyst precursor contains nickel in the form of an oxide, i.e., NiO.

[0109] When water is present, the water content is preferably between 150 and 900 grams per kilogram of dry air, even more preferably between 250 and 650 grams per kilogram of dry air.

[0110] (Step e) Reduction by reducing gas) Prior to the use of the catalyst in the catalytic reactor and the implementation of the hydrogenation method, a reduction treatment step e) is carried out in the presence of a reducing gas, resulting in a catalyst containing nickel at least partially in metallic form. This step is advantageously carried out in situ, i.e. after the loading of the catalyst into a reactor for the hydrogenation of aromatic or polyaromatic compounds. This treatment makes it possible to activate said catalyst and form metal particles, in particular particles of nickel in the zero-valent state. The in situ implementation of the catalyst reduction treatment makes it possible to dispense with an additional step of passivation of the catalyst with oxygen-carrying compounds or CO2. Passivation of the catalyst is necessary in the case where the catalyst is prepared by carrying out a reduction treatment ex situ, i.e. outside the reactor used for the hydrogenation of aromatic or polyaromatic compounds. In fact, when the reduction treatment is carried out ex situ, it is necessary to carry out a passivation step in order to protect the metallic phase of the catalyst in the presence of air (during the operations of transporting the catalyst and loading it into the hydrogenation reactor) and then carry out a new step of reducing the catalyst.

[0111] The reducing gas is preferably hydrogen. Hydrogen can be used in high purity or as a mixture (for example, a mixture of hydrogen / nitrogen, hydrogen / argon or hydrogen / methane). When hydrogen is used as a mixture, all proportions are conceivable.

[0112] According to one essential aspect of the preparation method according to the present invention, the temperature during the reduction treatment is 150° C. or higher and lower than 250° C., preferably 160° C. to 230° C., and more preferentially 170° C. to 220° C. The duration of the reduction treatment is between 5 minutes and less than 5 hours, preferably 10 minutes to 4 hours, and more preferentially 10 minutes to 110 minutes.

[0113] The presence of the nickel-copper alloy in at least partially reduced form makes it possible to use less severe operating conditions for reducing the nickel active phase than in the prior art, and therefore makes it possible to carry out the reduction step directly in the reactor in which it is desired to carry out the hydrogenation of aromatic or polyaromatic compounds.

[0114] Furthermore, the presence of copper in the catalyst makes it possible to protect the good activity and good service life of the catalyst when it is placed in contact with a hydrocarbon feedstock containing sulfur. Indeed, compared to nickel, the copper present in the catalyst more easily captures the sulfur-containing compounds contained in the feedstock, which limits the irreversible poisoning of the active sites. The temperature increase to the desired reduction temperature is generally set slow, for example between 0.1 and 10°C / min, preferably between 0.3 and 7°C / min.

[0115] The hydrogen flow rate is expressed in L / h / gram of catalyst precursor and is between 0.01 and 100 L / h / gram of catalyst precursor, preferably between 0.05 and 10 L / h / gram of catalyst precursor, and even more preferably between 0.1 and 5 L / h / gram of catalyst precursor.

[0116] (Step f) Passivation (optional) The catalyst prepared by the method according to the invention can advantageously undergo a passivation step with sulfur-containing compounds, which makes it possible to improve the selectivity of the catalyst and to avoid thermal runaway during the start-up of the new catalyst. Passivation generally consists in irreversibly poisoning the most toxic active sites of nickel present on the new catalyst with sulfur-containing compounds, thus weakening the activity of the catalyst that benefits its selectivity. The passivation step is carried out using methods known to those skilled in the art.

[0117] The passivation step with a sulfur-containing compound is generally carried out at temperatures between 20° C. and 350° C., preferably between 40 and 200° C., for a period of 10 to 240 minutes. The sulfur-containing compound is, for example, chosen from the following compounds: thiophenes, thiophanes, alkyl monosulfides, such as dimethyl sulfide, diethyl sulfide, dipropyl sulfide and propylmethyl sulfide, or also organic disulfides of formula HO-R1-SS-R2-OH, such as dithiodiethanol of formula HO-C2H4-SS-C2H4-OH (often called DEODS). The sulfur content is generally between 0.1% and 2% by weight of said element relative to the total weight of the catalyst.

[0118] In one embodiment according to the invention, the preparation of the catalyst is carried out ex situ, ie before loading the catalyst into the reaction unit of the process for the selective hydrogenation or hydrogenation of aromatics.

[0119] (Selective Hydrogenation Method) The catalyst obtained by the process according to the invention can be used in a process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, for example alkenyl aromatic compounds, also known as diolefinic compounds and / or acetylenic compounds and / or styrenic compounds, contained in hydrocarbon compounds having a final boiling point of less than or equal to 300° C. The process can be carried out in the presence of the catalyst obtained by the preparation process described above in this description, the temperature being 0° C. to 300° C., the pressure being 0.1 to 10 MPa, the molar ratio of hydrogen / polyunsaturated compounds to be hydrogenated being 0.1 to 10 if the process is carried out in the liquid phase, and the hourly space velocity being 0.1 to 200 h -1 or, if the process is carried out in the gas phase, the hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio is 0.5 to 1000, and the hourly space velocity is 100 to 40,000 h -1 It is.

[0120] Monounsaturated organic compounds, such as ethylene and propylene, are at the root of the production of polymers, plastics and other chemical products with added value. These compounds are obtained from natural gas, naphtha or gas oils, which are processed by the methods of steam cracking or catalytic cracking. These processes are carried out at high temperatures and give rise to polyunsaturated organic compounds, such as acetylene, propadiene and methylacetylene (or propyne), 1,2-butadiene and 1,3-butadiene, vinylacetylene and ethylacetylene, and other polyunsaturated compounds whose boiling points correspond to the C5+ fraction (hydrocarbon-based compounds having at least 5 carbon atoms), in particular diolefins or styrene or indene compounds. These polyunsaturated compounds are highly reactive and lead to side reactions in the polymerization unit. It is therefore necessary to remove them before making an economical use of these fractions.

[0121] Selective hydrogenation is the main process developed to specifically remove unwanted polyunsaturated compounds from these hydrocarbon feedstocks. It allows the conversion of polyunsaturated compounds to the corresponding alkenes or aromatic compounds while avoiding their complete saturation and therefore the formation of the corresponding alkanes or naphthenes. In the case of steam cracked gasoline used as feedstock, selective hydrogenation also allows the selective hydrogenation of alkenyl aromatic compounds to give aromatic compounds while avoiding the hydrogenation of the aromatic ring.

[0122] The hydrocarbon feedstock treated in the selective hydrogenation process has a final boiling point below 300° C., contains at least 2 carbon atoms per molecule and comprises at least one polyunsaturated compound. The term “polyunsaturated compounds” is intended to mean compounds containing at least one acetylene group and / or at least one diene group and / or at least one alkenyl aromatic group.

[0123] More particularly, the feedstock is selected from the group consisting of steam cracked C2 fraction, steam cracked C2-C3 fraction, steam cracked C3 fraction, steam cracked C4 fraction, steam cracked C5 fraction and steam cracked gasoline, also known as thermal cracked gasoline or C5+ fraction.

[0124] The steam cracked C2 fractions, which are advantageously used for the implementation of the selective hydrogenation process according to the invention, have, for example, the following composition: 40% to 95% by weight of ethylene and about 0.1% to 5% by weight of acetylene, the remainder being essentially ethane and methane. In some steam cracked C2 fractions, 0.1% to 1% by weight of C3 compounds may be present.

[0125] The steam cracked C3 fractions, which are advantageously used for the implementation of selective hydrogenation processes, have, for example, the following average composition: about 90% by weight of propylene and about 1% to 8% by weight of propadiene and methylacetylene, the remainder being essentially propane. In some C3 fractions, 0.1% to 2% by weight of C2 and C4 compounds may be present.

[0126] The C2-C3 fraction may also be advantageously used for the implementation of the selective hydrogenation process. It may, for example, have the following composition: acetylene in the range of 0.1% to 5% by weight, propadiene and methylacetylene in the range of 0.1% to 3% by weight, ethylene in the range of 30% by weight and propylene in the range of 5% by weight, the remainder being essentially methane, ethane and propane. This feedstock may contain C4 compounds in the range of 0.1% to 2% by weight.

[0127] The steam cracked C4 fraction, which is advantageously used for the implementation of the selective hydrogenation process, has, for example, the following average composition by weight: 1% by weight of butane, 46.5% by weight of butene, 51% by weight of butadiene, 1.3% by weight of vinylacetylene and 0.2% by weight of butyne. In some C4 fractions, 0.1% to 2% by weight of C3 and C5 compounds may be present.

[0128] The steam cracked C5 fraction, which is advantageously used for the implementation of the selective hydrogenation process, has, for example, the following composition: 21% by weight of pentane, 45% by weight of pentene and 34% by weight of pentadiene.

[0129] Steam cracked or pyrolysis gasoline, which is advantageously used for the implementation of the selective hydrogenation process, corresponds to a hydrocarbon fraction whose boiling point is generally between 0 and 300° C., preferably between 10 and 250° C. The polyunsaturated hydrocarbons present in the steam cracked gasoline to be hydrogenated are in particular diolefin compounds (butadiene, isoprene, cyclopentadiene, etc.), styrene compounds (styrene, α-methylstyrene, etc.) and indenic compounds (indene, etc.). Steam cracked gasoline generally contains C5-C12 fractions with traces of C3, C4, C13, C14 and C15 (for example 0.1% by weight to 3% by weight for each of these fractions). For example, a feedstock formed from pyrolysis gasoline generally has the following composition: 5% to 30% by weight of saturates (paraffins and naphthenes), 40% to 80% by weight of aromatics, 5% to 20% by weight of monoolefins, 5% to 40% by weight of diolefins, and 1% to 20% by weight of alkenyl aromatics, which together make up 100%. It also contains 0 to 1000 ppm by weight of sulfur, preferably 0 to 500 ppm by weight of sulfur.

[0130] Preferably, the polyunsaturated hydrocarbon feedstock treated by the selective hydrogenation process is a steam cracked C2 fraction or a steam cracked C2-C3 fraction or a steam cracked gasoline.

[0131] The selective hydrogenation process is aimed at removing the polyunsaturated hydrocarbons present in the feedstock to be hydrogenated, without hydrogenating the monounsaturated hydrocarbons. For example, if the feedstock is a C2 fraction, the selective hydrogenation process is aimed at selectively hydrogenating acetylene. If the feedstock is a C3 fraction, the selective hydrogenation process is aimed at selectively hydrogenating propadiene and methylacetylene. In the case of the C4 fraction, the objective is to remove butadiene, vinylacetylene (VAC) and butyne; in the case of the C5 fraction, the objective is to remove pentadiene. If the feedstock is steam cracked gasoline, the selective hydrogenation process is aimed at selectively hydrogenating the polyunsaturated hydrocarbons present in the feedstock to be treated, so that diolefinic compounds are particularly hydrogenated to give monoolefins and styrene and indene compounds are particularly hydrogenated to give the corresponding aromatic compounds, avoiding the hydrogenation of aromatic rings.

[0132] The technical implementation of the selective hydrogenation process is, for example, carried out by injection of the polyunsaturated hydrocarbon feedstock and hydrogen as an upflow or downflow into at least one fixed-bed reactor. The reactor may be of isothermal or adiabatic type. Adiabatic reactors are preferred. The polyunsaturated hydrocarbon feedstock may advantageously be diluted by reinjecting the effluent from the reactor in which the selective hydrogenation reaction was carried out one or more times at various points of the reactor located between the inlet and the outlet of the reactor, limiting the temperature gradient in the reactor. The technical implementation of the selective hydrogenation process may also advantageously be carried out by implantation of at least the supported catalyst in a reactive distillation column or a reactor-exchanger or a slurry type reactor. The hydrogen flow may be introduced simultaneously with the feedstock to be hydrogenated and / or at one or several different points of the reactor.

[0133] The selective hydrogenation of the steam cracked C2, C2-C3, C3, C4, C5 and C5+ fractions can be carried out in the gas or liquid phase, preferably in the liquid phase for the C3, C4, C5 and C5+ fractions and in the gas phase for the C2 and C2-C3 fractions. The liquid phase reaction allows to reduce the energy costs and increase the cycle period of the catalyst.

[0134] In general, the selective hydrogenation of a hydrocarbon feedstock containing polyunsaturated compounds containing at least two carbon atoms per molecule and having a final boiling point of 300° C. or less is carried out at a temperature between 0° C. and 300° C., at a pressure between 0.1 and 10 MPa, and for processes carried out in the liquid phase, the hydrogen / (polyunsaturated compounds to be hydrogenated) molar ratio is between 0.1 and 10, and the hourly space velocity HSV (defined as the ratio of the flow rate by the volume of the feedstock to the volume of the catalyst) is between 0.1 and 200 h . -1 or for processes carried out in the gas phase, in which the hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio is 0.5 to 1000, and the hourly space velocity HSV is 100 to 40,000 h -1 It is.

[0135] In one embodiment, when a selective hydrogenation process is carried out and the feedstock is a steam cracked gasoline containing polyunsaturated compounds, the molar ratio of (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally 0.5-10, preferably 0.7-5.0, more preferably 1.0-2.0, the temperature is 0° C.-200° C., preferably 20° C.-200° C., more preferably 30° C.-180° C., and the hourly space velocity (HSV) is generally 0.5-100 h -1 , preferably 1 to 50 hours -1 and the pressure is generally 0.3 to 8.0 MPa, preferably 1.0 to 7.0 MPa, and even more preferably 1.5 to 4.0 MPa.

[0136] More preferentially, when the selective hydrogenation process is carried out and the feedstock is steam cracked gasoline containing polyunsaturated compounds, the hydrogen / polyunsaturated compounds to be hydrogenated molar ratio is 0.7-5.0, the temperature is 20°C-200°C, and the hourly space velocity (HSV) is generally 1-50 h -1 and the pressure is 1.0 to 7.0 MPa.

[0137] Even more preferentially, when a selective hydrogenation process is carried out and the feedstock is steam cracked gasoline containing polyunsaturated compounds, the hydrogen / polyunsaturated compounds to be hydrogenated molar ratio is between 1.0 and 2.0, the temperature is between 30°C and 180°C, and the hourly space velocity (HSV) is generally between 1 and 50 h -1 and the pressure is 1.5 to 4.0 MPa.

[0138] The hydrogen flow rate is adjusted so that a sufficient amount is available to theoretically hydrogenate all of the polyunsaturated compounds and maintain an excess of hydrogen at the reactor outlet.

[0139] In another embodiment, when a selective hydrogenation process is carried out and the feedstock is a steam cracked C2 fraction and / or a steam cracked C2-C3 fraction containing polyunsaturated compounds, the molar ratio of (hydrogen) / (polyunsaturated compounds to be hydrogenated) is generally 0.5-1000, preferably 0.7-800, the temperature is 0° C.-300° C., preferably 15° C.-280° C., the hourly space velocity (HSV) is generally 100-40000 h -1 , preferably 500 to 30,000 h -1 The pressure is generally 0.1 to 6.0 MPa, and preferably 0.2 to 5.0 MPa.

[0140] (Method for hydrogenating aromatic compounds) The catalyst obtained by the process according to the invention may be used in a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point below 650° C., generally between 20° C. and 650° C., preferably between 20° C. and 450° C. Said hydrocarbon feedstock containing at least one aromatic or polyaromatic compound may be selected from the following petroleum or petrochemical fractions: reformates from catalytic reforming, kerosene, light gas oils, heavy gas oils, cracking distillates such as FCC recycle oils, coking unit gas oils or hydrocracked distillates.

[0141] The content of aromatic or polyaromatic compounds contained in the hydrocarbon feedstock treated in the hydrogenation process is generally between 0.1 and 80% by weight, preferably between 1 and 50% by weight, particularly preferably between 2 and 35% by weight, the percentages being based on the total weight of the hydrocarbon feedstock. The aromatic compounds present in the hydrocarbon feedstock are, for example, benzene or alkyl aromatic compounds, such as toluene, ethylbenzene, o-xylene, m-xylene or p-xylene, or also aromatic compounds having several aromatic rings (polyaromatics), such as naphthalene.

[0142] The sulfur or chlorine content of the feedstock is generally less than 5000 ppm by weight of sulfur or chlorine, preferably less than 100 ppm by weight, particularly preferably less than 10 ppm by weight.

[0143] The technical implementation of the process for the hydrogenation of aromatic or polyaromatic compounds is carried out, for example, by injection of the hydrocarbon feedstock and hydrogen as upflow or downflow into at least one fixed-bed reactor. Said reactor may be of isothermal or adiabatic type. Adiabatic reactors are preferred. The hydrocarbon feedstock may advantageously be diluted by one or more reinjections of the effluent from said reactor, in which the reaction for the hydrogenation of aromatic compounds was carried out, at various points of the reactor, located between the inlet and the outlet of the reactor, so that the temperature gradient in the reactor is limited. The technical implementation of the process for the hydrogenation of aromatic compounds may advantageously be carried out by implantation of at least said supported catalyst in a reactive distillation column or a reactor-exchanger or a slurry-type reactor. The hydrogen flow may be introduced simultaneously with the feedstock to be hydrogenated and / or at one or more different points of the reactor.

[0144] The hydrogenation of aromatic or polyaromatic compounds may be carried out in gas phase or liquid phase, and is preferably carried out in liquid phase. In general, the temperature during hydrogenation of aromatic or polyaromatic compounds is 30°C to 350°C, preferably 50°C to 325°C, the pressure during hydrogenation is 0.1 to 20MPa, preferably 0.5 to 10MPa, the molar ratio of hydrogen / (aromatic compound to be hydrogenated) is 0.1 to 10, and the hourly space velocity HSV during hydrogenation is 0.05 to 50h -1 , preferably 0.1 to 10 hours -1 and the hydrocarbon feedstock contains aromatic or polyaromatic compounds and has a final boiling point below 650°C, typically between 20°C and 650°C, preferably between 20°C and 450°C.

[0145] The hydrogen flow rate is adjusted so that a sufficient amount is available to theoretically hydrogenate all of the aromatics and maintain an excess of hydrogen at the reactor exit.

[0146] The conversion of aromatic or polyaromatic compounds is generally greater than 20 mol%, preferably greater than 40 mol%, more preferably greater than 80 mol%, particularly preferably greater than 90 mol% of the aromatic or polyaromatic compounds contained in the hydrocarbon feedstock. The conversion is calculated by dividing the difference between the total moles of aromatic or polyaromatic compounds in the hydrocarbon feedstock and in the product by the total moles of aromatic or polyaromatic compounds in the hydrocarbon feedstock.

[0147] According to a specific alternative form of the process, a process for hydrogenation of benzene from a hydrocarbon feedstock, for example a reformate derived from a catalytic reforming unit, is carried out, the benzene content in said hydrocarbon feedstock generally being between 0.1 and 40% by weight, preferably between 0.5 and 35% by weight, particularly preferably between 2 and 30% by weight, the weight percentages being based on the total weight of the hydrocarbon feedstock.

[0148] The sulfur or chlorine content of the feedstock is generally less than 10 ppm by weight, preferably less than 2 ppm by weight of sulfur or chlorine, respectively.

[0149] The hydrogenation of benzene contained in the hydrocarbon feedstock may be carried out in the gas phase or liquid phase, but is preferably carried out in the liquid phase. When it is carried out in the liquid phase, a solvent may be present, for example, cyclohexane, heptane or octane. In general, the temperature at which the hydrogenation of benzene is carried out is 30°C to 250°C, preferably 50°C to 200°C, more preferably 80°C to 180°C, the pressure at which it is carried out is 0.1 to 10 MPa, preferably 0.5 to 4 MPa, the molar ratio of hydrogen / (benzene) at which it is carried out is 0.1 to 10, and the hourly space velocity HSV at which it is carried out is 0.05 to 50 h -1 , preferably 0.5 to 10 hours -1 It is.

[0150] The benzene conversion is generally greater than 50 mol %, preferably greater than 80 mol %, more preferably greater than 90 mol %, particularly preferably greater than 98 mol %.

[0151] The present invention will now be illustrated by the following examples, which are not intended to be limiting in any way.

[0152] (Example) For all of the catalysts mentioned in the examples below, the support is alumina A, which has a specific surface area of ​​80 m 2 / g, the pore volume is 0.7 mL / g, and the median pore diameter is 12 nm.

[0153] Example 1: Preparation of an aqueous solution of Ni precursor The aqueous solution of Ni precursor (solution S1) used for the preparation of catalyst A is prepared by dissolving 43.5 g of nickel nitrate (NiNO3, supplier Strem Chemicals®) in a volume of 13 mL of distilled water. A solution S1 is obtained, the Ni concentration of which is 350 g Ni per liter of solution volume.

[0154] Example 2: Preparation of an aqueous solution of Ni precursor with organic compounds The aqueous solution of Ni precursor (solution S2) used for the preparation of catalysts B-G is prepared by dissolving 43.5 g of nickel nitrate (NiNO3, supplier Strem Chemicals®) and malonic acid (CAS 141-82-2; supplier Fluka®) in a volume of 13 mL of distilled water. The additive / Ni molar ratio is 0.5. Solution S2 is obtained. The Ni concentration of this solution S2 is 350 g Ni per liter of solution volume.

[0155] (Example 3: Preparation of an aqueous solution of a precursor of NiCu alloy (5% Ni)) The aqueous solution of Ni precursor (solution S3) used for the preparation of catalysts C, D, E and G is prepared by dissolving 14.5 g of nickel nitrate (NiNO3, supplier Strem Chemicals®) in a volume of 13 mL of distilled water. A solution is obtained whose Ni concentration is 116.6 g of Ni per liter of solution volume. Copper nitrate precursor is then added, in particular to have a molar ratio of Ni / Cu according to the examples 1 (catalysts C to F) and 2 (catalyst G). Solution S3 is obtained, which makes it possible to introduce the precursor of the NiCu alloy, the weight content of Ni relative to the final catalyst being about 5% by weight.

[0156] This solution is adapted to obtain an alloy containing 2% by weight of Ni relative to the final catalyst (catalyst F).

[0157] Example 4: Preparation of Catalyst A (not in accordance with the invention) Dry impregnation of solution S prepared in example 1 is carried out on 10 g of alumina A. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under a flow of dry air of 1 L / h / g of catalyst. The calcined catalyst thus prepared contains 15% by weight of elemental nickel relative to the total weight of the catalyst supported on the alumina.

[0158] The dry air used in this and all following examples contains less than 5 grams of water per kilogram of air weight.

[0159] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0160] Example 5: Preparation of Catalyst B (not in accordance with the invention) Dry impregnation of the solution S2 prepared in Example 2 is carried out on 10 g of alumina A. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under an air flow of 1 L / h / g of catalyst. The calcined catalyst thus prepared contains 15% by weight of elemental nickel relative to the total weight of the catalyst supported on the alumina.

[0161] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0162] Example 6: Preparation of Catalyst C (not in accordance with the invention) The simultaneous impregnation of solutions S2 and S3 prepared in examples 2 and 3 is carried out on 10 g of alumina A. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined at 450° C. for 2 hours under a flow of air of 1 L / h / g (catalyst).

[0163] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0164] Example 7: Preparation of Catalyst D (According to the Invention) Dry impregnation of solution S2 is carried out on 10 g of alumina A, resulting in 15% Ni alone relative to the total weight of the final catalyst. The solid thus obtained is subsequently dried in an oven at 120° C. overnight and then calcined at 450° C. for 2 hours under an air flow of 1 L / h / g (catalyst). Dry impregnation of solution S3 (targeted Ni / Cu molar ratio=3) is then carried out on the catalyst precursor. The targeted Ni content in this example is 5% Ni by weight relative to the weight of the final catalyst. The solid thus obtained is subsequently dried in an oven at 120° C. overnight and then calcined at 450° C. for 2 hours under an air flow of 1 L / h / g (catalyst).

[0165] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0166] Example 8: Preparation of Catalyst E (According to the Invention) Dry impregnation of solution S3 (targeted Ni / Cu molar ratio=3) is carried out on alumina A. The targeted Ni content in this example is 5% Ni by weight relative to the weight of the final catalyst. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under an air flow of 1 L / h / g (catalyst). Dry impregnation of solution S2 is then carried out on the catalyst precursor to obtain a sole Ni content of 15% relative to the total weight of the final catalyst. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under an air flow of 1 L / h / g (catalyst).

[0167] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0168] Example 9: Preparation of Catalyst F (According to the Invention) Dry impregnation of solution S2 is carried out on alumina A to obtain 15% Ni alone relative to the total weight of the final catalyst. The solid thus obtained is subsequently dried in an oven at 120° C. overnight and then calcined at 450° C. for 2 hours under an air flow of 1 L / h / g (catalyst). Dry impregnation of solution S3 prepared and adapted in example 3 is then carried out on the catalyst precursor. The Ni content targeted in this example is 2% Ni by weight relative to the weight of the final catalyst. The Ni / Cu ratio targeted is 3. The solid thus obtained is subsequently dried in an oven at 120° C. overnight and then calcined at 450° C. for 2 hours under an air flow of 1 L / h / g (catalyst).

[0169] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0170] Example 10: Preparation of Catalyst G (According to the Invention) Dry impregnation of solution S2 is carried out on alumina A to obtain a sole Ni content of 15% relative to the total weight of the final catalyst. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under an air flow of 1 L / h / g (catalyst). Dry impregnation of solution S3 prepared in example 3 is then carried out on the catalyst precursor. The Ni content targeted in this example is 2% by weight Ni relative to the weight of the final catalyst. The Ni / Cu molar ratio targeted is 1. The solid thus obtained is subsequently dried overnight in an oven at 120° C. and then calcined for 2 hours at 450° C. under an air flow of 1 L / h / g (catalyst).

[0171] The catalyst precursor is then reduced under the conditions described in Example 11 below.

[0172] Example 11: Characterization All catalysts contain the contents targeted during impregnation, i.e. 15% elemental nickel (characterized by X-ray fluorescence) relative to the total weight of the catalyst, and % of copper (characterized by X-ray fluorescence) added.

[0173] The amount of alloy obtained after calcination and subsequent reduction steps was determined by X-ray diffraction (XRD) analysis on a sample of the powdered catalyst.

[0174] The amount of nickel in metallic form obtained after the reduction step was determined by X-ray diffraction (XRD) analysis on a powdered catalyst sample. During the reduction step and the duration of the XRD characterization, the catalyst was never returned to the open air. The diffraction pattern was obtained by radiation crystallographic analysis on a diffractometer using conventional powder techniques with copper Kα1 radiation (λ=1.5406 Å).

[0175] The degree of reduction was evaluated by the Ni concentration located around 52°2θ on all the diffractograms of each sample of the analyzed catalyst. 0The area of ​​the line at 52° was calculated and then subtracted out the signal due to alumina which is present below the line at 52° and reaches ambient temperature as quickly as possible.

[0176] Table 1 below collates the degree of reduction of nickel metal Ni° or alternatively the content of nickel metal Ni° (expressed as weight % relative to the total weight of active nickel, i.e. nickel not constituting the alloy), for all catalysts A to G characterized by XRD after a reduction step under flowing hydrogen for 90 minutes at 170° C. These values ​​were also compared with the degree of reduction obtained for catalyst A (Ni alone) after a conventional reduction step (i.e. reduction under flowing hydrogen for 15 hours at a temperature of 400° C.).

[0177] Alumina in delta and theta morphology and large CuO and NiO lines are detected on all copper-nickel containing catalysts after calcination at ambient temperature.

[0178] After reduction, Ni 0.76 Cu 0.24 A line corresponding to the alloy in the form of is further detected after reduction.

[0179] The degree of reducing power and therefore Ni 0 To evaluate the formation of 0 The area of ​​the line of is measured by subtracting the signal due to alumina present on all diffractograms below the line at 52° as soon as possible after reaching ambient temperature. Therefore, the area of ​​the Ni crystallized after reduction is 0 It is possible to determine the relative percentages of

[0180] Table 1 below shows the degree of reducing power or Ni content for all catalysts characterized by XRD after reduction under flowing hydrogen at 170° C. for 90 minutes. 0The contents are summarized below. These values ​​were also compared with the degree of reduction obtained for catalyst A (Ni only) after a conventional reduction step (i.e. reduction under flowing hydrogen at a temperature of 400° C. for 15 hours).

[0181] [Table 1]

[0182] For catalyst A (15% pure Ni / alumina), the degree of nickel reducing power is 0% after exactly the same reduction treatment under hydrogen as for catalysts B to E. Reduction at 400°C is necessary to achieve about 80% reduction of nickel oxide to Ni°.

[0183] Catalyst C, prepared by simultaneous impregnation of solutions S2 and S3, has a single NiCu alloy and no single Ni° active phase according to XRD.

[0184] Post-impregnation or pre-impregnation of nickel with solution S3 having a nickel content of 2% (catalyst F) or 5% (catalysts D, E, G) at a Ni / Cu ratio of 3 (catalysts D, E, F) or 1 (catalyst G) also resulted in the formation of nickel oxides of about 90% at the edge of the catalyst. 0 This allows for a return to

[0185] Example 12: Catalytic testing: Performance in selective hydrogenation of mixtures containing styrene and isoprene (A HYD1 )) Catalysts A to G described in the above examples are tested in a reaction for the selective hydrogenation of a mixture containing styrene and isoprene.

[0186] The composition of the feedstock to be selectively hydrogenated is as follows: 8% by weight of styrene (supplied by Sigma Aldrich®, purity 99%), 8% by weight of isoprene (supplied by Sigma Aldrich®, purity 99%) and 84% by weight of n-heptane (solvent) (supplied by VWR®, purity >99% Chromanorm® HPLC). This composition corresponds to the initial composition of the reaction mixture. This mixture of model molecules is typical of pyrolysis gasoline.

[0187] The selective hydrogenation reaction is carried out in a 500 mL stainless steel autoclave equipped with a magnetically driven mechanical stirrer and capable of operating at a maximum pressure of 100 bar (10 MPa) and temperatures between 5°C and 200°C.

[0188] 214 mL of n-heptane (supplier VWR®, purity >99% Chromanorm HPLC) and a quantity of 3 mL of catalyst are added to the autoclave. The autoclave is closed and purged. The autoclave is then pressurized under 35 bar (3.5 MPa) of hydrogen. The catalyst is first reduced in situ for catalysts A to G (here corresponding to step e) of the preparation method according to the invention according to one embodiment) at 170° C. for 90 minutes under a hydrogen flow of 1 L / h / g (temperature increase gradient is 1° C. / min). The autoclave is then brought to a test temperature equal to 30° C. At time t=0, about 30 g of a mixture containing styrene, isoprene, n-heptane, pentanethiol and thiophene are introduced into the autoclave. The reaction mixture then has the composition described above and stirring is started at 1600 rpm. In the autoclave, the pressure is kept constant at 35 bar (3.5 MPa) by means of a storage cylinder placed upstream of the reactor.

[0189] Another test was run on Catalyst A, where the catalyst reduction temperature was 400° C. for 15 hours.

[0190] The progress of the reaction is monitored by taking samples at regular intervals from the reaction medium: styrene is hydrogenated to give ethylbenzene, there is no hydrogenation of the aromatic ring, and isoprene is hydrogenated to give methylbutenes. If the reaction is extended longer than necessary, the methylbutenes are then themselves hydrogenated to give isopentane. Hydrogen consumption is also monitored over time by the reduction in pressure in a storage cylinder located upstream of the reactor. The catalytic activity is expressed in moles of H2 consumed per minute and per weight (gram) of Ni.

[0191] The catalytic activities measured for catalysts A to G are recorded in Table 2 below. They are compared with the catalytic activities measured for catalyst A prepared under conventional reduction conditions (under hydrogen flow at a temperature of 400° C. for 15 hours) (A HYD1 )

[0192] Example 13: Catalytic testing: performance in hydrogenation of toluene (A HYD2 )) Catalysts A to G described in the above examples are also tested in the reaction for the hydrogenation of toluene.

[0193] The selective hydrogenation reaction is carried out in an autoclave identical to that described in Example 10.

[0194] 214 mL of n-heptane (supplier VWR®, purity >99% Chromanorm HPLC) and a quantity of 3 mL of catalyst are added to the autoclave. The autoclave is closed and purged. It is then pressurized under 35 bar (3.5 MPa) of hydrogen. The catalyst is first reduced in situ for catalysts A to G (here corresponding to step e) of the preparation method according to the invention according to one embodiment) at 170° C. for 90 minutes under a hydrogen flow of 1 L / h / g (temperature increase gradient is 1° C. / min). After the addition of 216 mL of n-heptane (supplier VWR®, purity >99% Chromanorm HPLC), the autoclave is closed, purged and then pressurized under 35 bar (3.5 MPa) of hydrogen and a test temperature equal to 80° C. At time t=0, about 26 g of toluene (supplier SDS®, purity >99.8%) are introduced into the autoclave (initial composition of the reaction mixture is 6% by weight toluene / 94% by weight n-heptane) and stirring is started at 1600 rpm. The pressure in the autoclave is kept constant at 35 bar (3.5 MPa) by means of a storage cylinder located upstream of the reactor.

[0195] The progress of the reaction is monitored by taking samples from the reaction medium at regular time intervals: toluene is completely hydrogenated to give methylcyclohexane. Hydrogen consumption is also monitored over time by the drop in pressure in a storage cylinder located upstream of the reactor. The catalytic activity is expressed in moles of H2 consumed per minute and per weight (gram) of Ni.

[0196] The catalytic activities measured for catalysts A to G are recorded in Table 2 below. They are compared with the catalytic activities measured for catalyst A, which was prepared under conventional reduction conditions (in an ex situ continuous flow reactor under hydrogen flow at a temperature of 400° C. for 15 hours) (A HYD2 ) can be related back to

[0197] [Table 2]

[0198] Catalysts A and B reduced at 170° C. for 90 min are not active due to their reduced Ni content of 0. On the other hand, if the temperature is increased to 400° C., catalyst A is active due to its reduced Ni content of around 80%. However, the particle size of 14 nm gives it a relatively modest catalytic activity. Catalyst C does not have reduced Ni alone according to XRD, and the activity evaluated in Examples 11 and 12 is much lower than reduced Ni alone (much lower activity (around 20%) compared to the reference) due to the presence of an alloy with slight hydrogenation properties.

[0199] This clearly shows the improved performance of catalysts D-G according to the invention compared to the completely inactive catalyst of Ni alone on alumina reduced for 90 min at 170° C. Furthermore, the small particles obtained by using solution 2 allow a substantial activity gain even compared to catalyst A reduced at 400° C.

Claims

1. A catalyst for selective hydrogenation of polyunsaturated compounds or aromatic compounds, comprising nickel and copper, the nickel content being 1% to 50% by weight relative to the total weight of the catalyst, and a second metallic element, copper, being 0.5% to 15% by weight relative to the total weight of the catalyst, the catalyst comprising an alumina carrier, the molar ratio between nickel and copper is between 0.5 and 5 mol / mol; at least a portion of the nickel and copper is in the form of a nickel-copper alloy; the nickel content in the nickel-copper alloy is between 0.5% and 15% by weight of elemental nickel relative to the total weight of the catalyst; The size of the nickel particles in the catalyst, measured in the oxide form, is less than 7 nm. A catalyst characterized by:

2. 2. The catalyst of claim 1, wherein the size of the nickel particles in the catalyst is less than 5 nm.

3. Catalyst according to claim 1 or 2, characterized in that the support is in the form of extrudates having a mean diameter between 0.5 and 10 mm.

4. Catalyst according to claim 3, characterized in that the support is in the form of trilobal or tetralobal extrudates.

5. A process for preparing the catalyst according to any one of claims 1 to 4, comprising the following steps: a) contacting an alumina support with at least one solution containing only at least one nickel precursor as the metal precursor; b) contacting the alumina support with at least one solution containing at least one nickel precursor and at least one copper precursor; c) contacting the alumina support with at least one solution containing at least one organic compound containing at least one carboxylic acid group, or at least one alcohol group, or at least one ester group, or at least one amide group, or at least one amine group; It is understood that: - steps a), b) and c) are carried out separately and in any order, or - steps a) and c) are carried out simultaneously, with step b) being carried out either before or after the combination of steps a) and c); - steps b) and c) are carried out simultaneously, with step a) being carried out either before or after the combination of steps b) and c); d) carrying out at least one step of drying the catalyst precursor obtained at the end of steps a) to c) at a temperature below 250° C.; a heat treatment step of the dried catalyst precursor obtained at the end of step d) at a temperature between 250° C. and 1000° C. under an inert or oxygen-containing atmosphere; e) carrying out a step of reducing the catalyst precursor obtained at the end of the heat treatment step by contacting said precursor with a reducing gas at a temperature of ≧150° C. and <250° C. A method comprising:

6. 6. The method according to claim 5, wherein the molar ratio between the organic compound introduced in step c) and elemental nickel also introduced in step a) is 0.01-5.0 mol / mol.

7. 7. The method according to claim 5 or 6, wherein the organic compound in step c) 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, proline, serine, EDTA.

8. The process according to any one of claims 5 to 7, wherein step e) is carried out at a temperature of from 160°C to 190°C.

9. The method according to any one of claims 5 to 8, wherein step e) is carried out for 10 minutes to 110 minutes.

10. The method according to any one of claims 5 to 9, wherein the copper precursor is selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride.

11. The method of claim 10 , wherein the copper precursor is copper nitrate.

12. A process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, which are contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 300° C., which is carried out in the presence of a catalyst according to any one of claims 1 to 4, the temperature being between 0° C. and 300° C., the pressure being between 0.1 and 10 MPa, the hydrogen / polyunsaturated compound to be hydrogenated molar ratio being between 0.1 and 10 if the process is carried out in the liquid phase, and the hourly space velocity being between 0.1 and 200 h －１ or, if the process is carried out in the gas phase, the hydrogen / polyunsaturated compound to be hydrogenated molar ratio is from 0.5 to 1000, the hourly space velocity being from 100 to 40,000 h －１ That is, the method.

13. A process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of less than or equal to 650° C., which is carried out in the gas or liquid phase in the presence of a catalyst according to any one of claims 1 to 4, wherein the temperature is between 30° C. and 350° C., the pressure is between 0.1 and 20 MPa, the hydrogen / aromatic compound to be hydrogenated molar ratio is between 0.1 and 10, and the hourly space velocity HSV is between 0.05 and 50 h －１ That is, the method.

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