Method for preparing a catalyst containing an active nickel phase and a nickel-copper alloy

Abstract

The present invention relates to a method for preparing a catalyst comprising nickel, copper and a porous alumina support, and comprises the following steps: a) contacting an alumina support with a solution containing a nickel precursor and a first organic compound having at least one carboxylic acid functional group; b) drying at a temperature of less than 250 °C and then calcining at a temperature of 250 °C to 550 °C; c) contacting the calcined catalyst precursor obtained at the end of step b) with a solution containing a nickel precursor, a copper precursor and a second organic compound having at least one carboxylic acid functional group; d) drying at a temperature of less than 250 °C.

Description

Technical Field

[0001] The present invention relates to a supported metal catalyst based on nickel and copper, particularly directed to the hydrogenation of unsaturated hydrocarbons, more particularly the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatic compounds.

Background Art

[0002] Catalysts for the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatic compounds are generally based on metals from Group VIII of the periodic table, for example nickel. The metal is in the form of nanometer-sized metal particles deposited on a support which may be a refractory oxide. The content of the metal from Group VIII, the optional presence of a second metal element, the size of the metal particles and the distribution of the active phase in the support, as well as the nature and pore distribution of the support are parameters which may affect the performance of the catalyst.

[0003] The rate of the hydrogenation reaction is governed by several criteria, for example, the diffusion of the reactants towards the surface of the catalyst (external diffusion limit), the diffusion of the reactants in the porous part of the support towards the active sites (internal diffusion limit) and the intrinsic properties of the active phase, for example, the size of the metal particles and the distribution of the active phase in the support.

[0004] For the purpose of obtaining better catalyst performance, particularly better selectivity and / or activity, it is known in the prior art to use additives of the organic compound type for the preparation of metal catalysts for selective hydrogenation. For example, Patent Document 1 discloses a method for the preparation of a selective hydrogenation catalyst comprising a support and an active phase containing a metal from Group VIII, said catalyst being prepared by a method comprising an impregnation step of the support with a solution containing a precursor of the metal from Group VIII and an organic additive, more particularly an organic compound having 1 to 3 carboxylic acid functional groups, a step of drying the impregnated support, and a step of calcining the dried support to obtain the catalyst.

[0005] Furthermore, in order to improve the performance level in selective hydrogenation, the promotion of nickel-based catalysts has often been proposed. For example, from Patent Document 2, it is known to use nickel- and silver-based catalysts for the selective hydrogenation of C4-C 10 diolefins. Furthermore, it is known to promote mainly present nickel with metals from Group IB, in particular gold (Patent Document 3) or tin (Patent Document 4). Patent Document 5 discloses a catalyst for the implementation of a selective hydrogenation process comprising a support and an active metal phase deposited on this support, the active metal phase comprising copper and at least one metal of nickel or cobalt in a molar ratio of Cu:(Ni and / or Co) greater than 1.

[0006] Finally, prior to the adoption of such a catalyst and its use in a hydrogenation process, a reduction treatment step in the presence of a reducing gas is carried out to obtain a catalyst comprising an active phase at least partially in metallic form. This treatment activates the catalyst and makes it possible to form metal particles. This treatment may be carried out in situ or ex situ, i.e., after or before the catalyst is loaded into the hydrogenation reactor.

[0007] Patent Document 6 discloses a catalyst comprising nickel and copper and an alumina support, wherein nickel and copper are present in a proportion of 1 wt% to 50 wt% by weight of nickel element relative to the total weight of the catalyst and in a proportion of 0.5 wt% to 15 wt% by weight of copper element relative to the total weight of the catalyst, and the catalyst is obtained via a preparation method comprising the following steps: a) contacting the 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 functional group, or at least one alcohol functional group, or at least one ester functional group, or at least one amide functional group, or at least one amine functional group; It is understood that: - steps a), b) and c) are carried out separately in any order; or - steps a) and c) are carried out simultaneously, and step b) is carried out either before or after the combination of steps a) and c); - steps b) and c) are carried out simultaneously, and step a) is 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; e) carrying out a step of reducing the catalyst precursor obtained at the end of step d) by contacting the precursor with a reducing gas at a temperature of 150 °C or more and less than 250 °C.

[0008] Continuing research in the field of catalysts for the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatic compounds, the Applicant has now confirmed that a metal phase based on nickel and copper can be used to prepare a particularly active catalyst by depositing a precursor of the nickel-based active phase in the presence of a specific organic additive and by carrying out a specific preparation method added to the catalyst in the presence of a specific organic additive.

[0009] Without wishing to be bound by any theory, during the preparation of the catalyst, a step is carried out of contacting the catalyst with a solution simultaneously containing a copper-based metal precursor, a nickel-based metal precursor and a specific organic additive, and subsequently, in the presence of a reducing gas, a step of drying and reducing at a low temperature (150 °C or higher and lower than 200 °C) is carried out, whereby it becomes possible to obtain a nickel-copper alloy (in a reduced form), and it has been observed by the applicant that this alloy can unexpectedly significantly improve the reducibility of the nickel active phase on the support, and the said nickel active phase is supplied in a step before the formation of the nickel-copper alloy (reduced form). Therefore, by the preparation method according to the present invention, it becomes possible to carry out a step of reducing a metal element at a lower temperature and with a shorter reaction time than those generally used in the prior art in the presence of a reducing gas. Advantageously, by using operating conditions that are not more severe than those of the prior art, it becomes possible to directly carry out the reduction step in a reactor for the purpose of hydrogenating an aromatic compound. However, the addition of nickel and copper after the addition of the active nickel phase inevitably causes the nickel particles to grow, and thus the activity is substantially lost. For this reason, the applicant has identified that it is possible to limit the growth of the nickel particles and even completely avoid it by adding a specific organic additive at a content much higher than the content used during the impregnation of the active nickel phase.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Means for Solving the Problems

[0011] (Subject Matter of the Invention) One subject of the present invention is a catalyst comprising nickel and copper and a porous alumina support, wherein the nickel is present in a proportion of 1 wt% to 50 wt% by weight of nickel element relative to the total weight of the catalyst, and the copper is present in a proportion of 0.5 wt% to 15 wt% by weight of copper element relative to the total weight of the catalyst, and the size of the nickel particles in the catalyst, measured in oxide form, is less than 5 nm, and relates to a method for preparing the catalyst, which method comprises at least the following steps: a) contacting an alumina support with at least one solution containing at least one first nickel precursor and at least one first organic compound containing at least one carboxylic acid functional group; obtaining a first catalyst precursor; b) drying the first catalyst precursor obtained at the end of step a) at a temperature below 250 °C and then calcining the dried first catalyst precursor at a temperature of 250 °C to 550 °C; obtaining a calcined catalyst precursor; c) contacting the calcined catalyst precursor obtained at the end of step b) with at least one solution containing at least one second nickel precursor, at least one copper precursor, and at least one second organic compound containing at least one carboxylic acid functional group; obtaining a second catalyst precursor; d) drying the second catalyst precursor obtained at the end of step c) at a temperature below 250 °C.

[0012] According to one or more embodiments, the molar ratio between the organic compound introduced in step a) and the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol.

[0013] According to one or more embodiments, the molar ratio between the organic compound introduced in step c) and the nickel element also introduced in step c) is 0.02 to 5 mol / mol.

[0014] According to one or more embodiments, the molar ratio between the nickel introduced between steps a) and c) and the copper introduced during step c) is 0.5 to 5 mol / mol.

[0015] According to one or more embodiments, the ratio between the molar ratio of the second organic compound to the nickel introduced in step c) and the molar ratio of the first organic compound to the nickel introduced in step a) is greater than 1.5.

[0016] According to one or more embodiments, steps a) and b) are performed at least twice before performing step c).

[0017] According to one or more embodiments, the first organic compound in step a) and the second organic compound in step c) are selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid, and levulinic acid.

[0018] According to one or more embodiments, the first organic compound in step a) and the second organic compound in step c) are the same.

[0019] According to one or more embodiments, the copper precursor is selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide, and copper fluoride.

[0020] According to one or more embodiments, the first nickel precursor and / or the second nickel precursor is nickel nitrate, nickel chloride, nickel acetate, or nickel hydroxycarbonate.

[0021] According to one or more embodiments, the method also includes step e), and the catalyst obtained at the end of step d) is calcined at a temperature of 250°C to 550°C.

[0022] According to one or more embodiments, the method also includes step f), and the catalyst obtained at the end of step d), optionally the catalyst obtained at the end of step e), is reduced by contacting the catalyst with a reducing gas at a temperature of 150°C or higher and lower than 250°C.

[0023] Another subject according to the present invention relates to a catalyst obtained via the preparation method according to the present invention.

[0024] Another subject according to the present invention relates to a method 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 300°C or lower. The method is carried out in the presence of a catalyst according to the present invention or a catalyst obtained by the preparation method according to the present invention. The temperature at that time is 0°C to 300°C, the pressure at that time is 0.1 to 10 MPa. When the method is carried out in the liquid phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.1 to 10, and the space-time velocity at that time is 0.1 to 200 h -1 or, when the method is carried out in the gas phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.5 to 1000, and the space-time velocity at that time is 100 to 40,000 h -1 is.

[0025] Another subject according to the present invention relates to a method for the hydrogenation of at least one aromatic or polyaromatic compound present in a hydrocarbon feedstock having a final boiling point of 650°C or lower. The method is carried out in the gas phase or in the liquid phase, in the presence of a catalyst according to the present invention or a catalyst obtained by the preparation method according to the present invention. The temperature at that time is 30°C to 350°C, the pressure at that time is 0.1 to 20 MPa, the molar ratio of hydrogen / (aromatic compound to be hydrogenated) at that time is 0.1 to 10, and the space-time velocity at that time is 0.05 to 50 h -1 is.

Best Mode for Carrying Out the Invention

[0026] (Detailed Description of the Invention) (1. Definitions) Subsequently, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor-in-chief D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIII (or Group VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification.

[0027] In this specification, in accordance with the IUPAC convention, "micropores" are understood to mean pores with a diameter of less than 2 nm, i.e., less than 0.002 μm; "mesopores" are understood to mean pores with a diameter greater than 2 nm, i.e., greater than 0.002 μm and less than 50 nm, i.e., less than 0.05 μm, and "macropores" are understood to mean pores with a diameter greater than 50 nm, i.e., greater than 0.05 μm.

[0028] The total pore volume is measured by mercury porosimetry according to standard ASTM D4284 - 92 at a wetting angle of 140°, with a wetting angle of 140°. For example, it is measured using a Micromeritics® brand AUTOPORE III® model device.

[0029] The BET specific surface area is measured by nitrogen physical adsorption according to standard ASTM D3663 - 03, and the method is described in the research book Adsorption by Powders & Porous Solids: Principle, Methodology and Applications, Academic Press, 1999 by Rouquerol F., Rouquerol J., and Singh K.

[0030] The mesopore median diameter is also defined as the diameter such that all pores having a size less than this diameter from among the total pores constituting the mesopore volume constitute 50% of the total mesopore volume determined by mercury porosimetry intrusion.

[0031] The term "size of nickel particles" is understood to mean the diameter of nickel crystallites in oxide form. The diameter of nickel crystallites in oxide form is determined by X-ray diffraction from the width of the diffraction line located at an angle 2θ = 43° (i.e., along the crystallographic direction

[0200] ) using Scherrer's relational expression. This method used in X-ray diffraction of polycrystalline samples or powders, which relates the full width at half maximum of the diffraction peak 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.

[0032] The nickel and copper contents are measured by fluorescent X-ray.

[0033] In this specification, the term "comprise" is synonymous with "include" and "contain" (means the same thing), is inclusive or non-limiting, and does not exclude other elements not described. It is understood that the term "comprise" includes the exclusive and limiting term "consist of". Also, in this specification, the term "substantially" corresponds to around ±10%, preferably ±5%, most preferably ±2% of a reference value, for example, distance, speed, flow rate, content rate of a compound, temperature, pressure, etc.

[0034] (2. Method for Preparation of Catalyst) The steps of the preparation method are described in detail below.

[0035] (Step a) contacting the support with a first nickel precursor and a first organic compound) The deposition of the first nickel precursor and the first organic compound containing at least one carboxylic acid functional group on the support can be carried out by dry impregnation, excess impregnation, or deposition-precipitation according to methods well known to those skilled in the art by carrying out step a).

[0036] Preferably, step a) is carried out by dry impregnation, which consists of contacting the catalyst support with at least the first nickel precursor and a solution containing at least one first organic compound containing a carboxylic acid functional group, and the volume of the solution is 0.25 to 1.5 times the pore volume of the support to be impregnated.

[0037] Step a) is preferably carried out by impregnation of the support, which consists, for example, of placing the support in contact with at least one solution, which is aqueous or organic (e.g., methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)) or actually consists of a mixture of water and at least one organic solvent and contains at least the first nickel precursor in at least partially dissolved state and at least the first organic compound containing a carboxylic acid functional group, or alternatively, the support is contacted with at least one colloidal solution of at least one nickel precursor in oxidized form (nickel oxide, oxy(hydroxide) or hydroxide nanoparticles) or reduced form (nickel metal nanoparticles in reduced state) and at least one first organic compound containing a carboxylic acid functional group. Preferably, the solution is aqueous. The pH of this solution can be modified by optional addition of an acid or a base.

[0038] Preferably, the first nickel precursor is introduced into an aqueous solution, for example, in the form of nitrates, carbonates, acetates, chlorides or oxalates, in the form of a complex formed by a polyacid or an acidic alcohol and its salts, in the form of a complex formed by acetylacetonate, or in the form of any other inorganic derivative soluble in an aqueous solution, and brought into contact with the carrier. Preferably, nickel nitrate, nickel chloride, nickel acetate or nickel hydroxycarbonate is advantageously used as the first nickel precursor. Most preferably, the first nickel precursor is nickel nitrate.

[0039] The concentration of nickel in the solution is still adjusted according to the pore volume of the available carrier, and for the supported catalyst, the content of the nickel element is 1 wt% to 50 wt%, more preferably 2 wt% to 40 wt%, even more preferably 3 wt% to 35 wt%, and even more preferably 5 wt% to 28 wt% by weight relative to the total weight of the catalyst.

[0040] The first organic compound containing at least one carboxylic acid functional 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.

[0041] The first saturated or unsaturated aliphatic organic compound or the aromatic organic compound containing at least one carboxylic acid functional group may be selected from monocarboxylic acids, dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids.

[0042] Advantageously, the first organic compound containing at least one carboxylic acid functional group is selected from oxalic acid, malonic acid, glutaric acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid or levulinic acid.

[0043] Advantageously, the molar ratio of the first organic compound introduced in step a) to the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol, preferably 0.05 to 2.0 mol / mol, more preferably 0.1 to 1.5 mol / mol, even more preferably 0.3 to 1.2 mol / mol.

[0044] (Step b) Drying and calcination) The first precursor of the catalyst obtained at the end of step a) is then dried at a temperature of less than 250°C, preferably 15°C to 180°C, more preferably 30°C to 160°C, even more preferably 50°C to 150°C, and in an even more preferred manner 70°C to 140°C, typically for a period of 0.5 hours to 12 hours, more preferably 0.5 hours to 5 hours. Longer periods are not excluded but do not necessarily contribute to improvement.

[0045] The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere or an oxygen-containing atmosphere or a mixture of an inert gas and oxygen. It is advantageously carried out at atmospheric pressure or reduced pressure. Preferably, this step is carried out at atmospheric pressure in the presence of air or nitrogen.

[0046] After drying, the first dried catalyst precursor is calcined at a temperature of 250°C to 600°C, preferably 350°C to 550°C, typically for a period of 0.5 to 24 hours, preferably for a period of 0.5 to 12 hours, even more preferably for a period of 0.5 to 10 hours, preferably in an inert atmosphere or an oxygen-containing atmosphere. Longer periods are not excluded but do not necessarily contribute to the improvement.

[0047] (Step c) contacting the calcined catalyst precursor with a copper precursor, a second nickel precursor and a second organic compound) The deposition of nickel, copper and a second organic compound containing at least one carboxylic acid functional group on the calcined catalyst precursor obtained at the end of step b) can be carried out by dry impregnation or excess impregnation, or by deposition-precipitation by methods well known to those skilled in the art.

[0048] Preferably, said step c) is carried out by dry impregnation, which consists of contacting the calcined catalyst precursor with a solution containing at least one nickel precursor, at least one copper precursor and at least one second organic compound containing at least one carboxylic acid functional group, preferably consisting of them, the volume of the solution being 0.25 times to 1.5 times the pore volume of the support to be impregnated.

[0049] Step c) is preferably carried out by co-impregnation of the calcined catalyst precursor obtained at the end of step b), for example, by contacting the calcined catalyst precursor with at least one solution, which solution is aqueous or organic (e.g., methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)), or consists of a mixture of water and at least one organic solvent. It contains at least one second nickel precursor in at least partially dissolved state, at least one copper precursor in at least partially dissolved state, and at least one second organic compound containing at least one carboxylic acid functional group, preferably consisting of them, or the calcined catalyst precursor is contacted with at least one colloidal solution containing at least one nickel precursor and at least one copper precursor in oxidized form (nickel and copper oxides, oxy(hydroxides) or hydroxide nanoparticles) or reduced form (nickel and copper metal nanoparticles in reduced state) and at least one second organic compound containing at least one carboxylic acid functional group, preferably consisting of them. Preferably, the solution is aqueous. The pH of this solution may be modified by optional addition of an acid or a base.

[0050] Preferably, the second nickel precursor and copper precursor are introduced into an aqueous solution.

[0051] When the second nickel precursor is introduced into an aqueous solution, it is advantageously used in the form of a nitrate, carbonate, acetate, chloride, hydroxide, hydroxycarbonate, oxalate, sulfate or formate, a complex formed by a polyacid or an acid alcohol and its salts, a complex formed by acetylacetonate, a complex of tetramine or hexamine, or any other inorganic derivative soluble in the aqueous solution. This second nickel precursor is brought into contact with the catalyst precursor. Preferably, nickel nitrate, nickel hydroxide, nickel carbonate, nickel chloride or nickel hydroxycarbonate is advantageously used as the second nickel precursor. Most preferably, the second nickel precursor is nickel nitrate, nickel carbonate or nickel hydroxide.

[0052] When the copper precursor is introduced into an aqueous solution, a copper precursor in mineral or organic form is advantageously used. In mineral form, the copper precursor can be selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide or copper fluoride. Most preferably, the copper precursor salt is copper nitrate.

[0053] The second nickel precursor is advantageously supplied at the desired concentration in step c) and gives, on the final catalyst (i.e., that obtained at the end of the reduction step e) if the drying / firing step d) or the reduction step e) is carried out), from 0.5 wt% to 10 wt%, preferably from 0.5 wt% to 8 wt%, more preferably from 1 wt% to 7 wt%, even more preferably from 1 wt% to 5 wt% by weight of nickel element relative to the total weight of the final catalyst.

[0054] The amount of one or more copper precursors introduced into the solution by step c) is selected such that the total copper content is from 0.5 wt% to 15 wt%, preferably from 0.5 wt% to 12 wt%, preferably from 0.75 wt% to 10 wt%, even more preferably from 1 wt% to 9 wt% by weight of copper element relative to the total weight of the final catalyst (i.e., that obtained at the end of the reduction step e) if the drying / firing step d) or the reduction step e) is carried out).

[0055] The second organic compound containing at least one carboxylic acid functional 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.

[0056] The second saturated or unsaturated aliphatic organic compound or the aromatic organic compound containing at least one carboxylic acid functional group may be selected from monocarboxylic acid, dicarboxylic acid, tricarboxylic acid or tetracarboxylic acid.

[0057] Advantageously, the second organic compound containing at least one carboxylic acid functional group is selected 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).

[0058] Advantageously, the molar ratio of the second organic compound introduced in step c) to the nickel element also introduced in step c) is 0.02 to 5 mol / mol, preferably 0.1 to 3 mol / mol, more preferably 0.2 to 2 mol / mol, and even more preferably 0.3 to 2 mol / mol.

[0059] Advantageously, the ratio between the molar ratio between the second organic compound and nickel introduced in step c) and the molar ratio between the first organic compound and nickel introduced in step a) is 1.5 or more, preferably 2 to 5.

[0060] Advantageously, the second organic compound introduced in step c) is the same as the first organic compound introduced in step a).

[0061] (Step d) Drying) Next, the second precursor of the catalyst obtained at the end of step a) is then dried at a temperature of less than 250 °C, preferably 15 °C to 180 °C, more preferably 30 °C to 160 °C, even more preferably 50 °C to 150 °C, and even more preferably 70 °C to 140 °C, typically for a period of 0.5 hours to 12 hours, more preferably for a period of 0.5 hours to 5 hours. Longer periods are not excluded but do not necessarily contribute to improvement.

[0062] The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out under an inert atmosphere or an oxygen-containing atmosphere or a mixture of an inert gas and oxygen. It is advantageously carried out at atmospheric pressure or reduced pressure. Preferably, this step is carried out in the presence of atmospheric pressure and air or nitrogen.

[0063] (Step e) Calcination (optional)) After drying, the catalyst obtained at the end of step d) is advantageously calcined at a temperature of 250 °C to 600 °C, preferably 350 °C to 550 °C, typically for a period of 0.5 to 24 hours, preferably for a period of 0.5 to 12 hours, even more preferably for a period of 0.5 to 10 hours, preferably under an inert atmosphere or an oxygen-containing atmosphere. Longer periods are not excluded but do not necessarily contribute to improvement.

[0064] (Step f) Reduction with a reducing gas (optional)) In one embodiment according to the present invention, before the use of the catalyst in the catalytic reactor and the implementation of the hydrogenation process, a reduction treatment step f) is carried out in the presence of a reducing gas to obtain a catalyst containing nickel that is at least partially in metallic form. This step is preferably carried out on-site, i.e., after the catalyst is loaded into the hydrogenation reactor. This treatment activates the catalyst and enables the formation of metal particles, particularly nickel particles in the zero-valent state. The on-site implementation of the catalyst reduction treatment makes it possible to omit an additional step of passivating the catalyst by oxygen-bearing compounds or CO2, which is necessarily the case when the catalyst is prepared by carrying out the reduction treatment outside the site, i.e., outside the reactor used for the hydrogenation of aromatic or polyaromatic compounds. In fact, when the reduction treatment is carried out outside the site, it is necessary to carry out a passivation step to preserve the metal phase of the catalyst in the presence of air (during the operations of transporting and loading the catalyst into the hydrogenation reactor), and then carry out a new step of reducing the catalyst.

[0065] The reducing gas is preferably hydrogen. Hydrogen may be used in high purity or as a mixture (e.g., a mixture of hydrogen / nitrogen, hydrogen / argon, or hydrogen / methane). In the case where hydrogen is used as a mixture, any ratio may be assumed.

[0066] The reduction treatment is carried out at a temperature of 150°C or higher and less than 250°C, preferably 160 - 230°C, and more preferably 170 - 220°C. The duration of the reduction treatment is between 5 minutes and less than 5 hours, preferably 10 minutes - 4 hours, and even more preferably 10 minutes - 210 minutes.

[0067] The presence of a nickel-copper alloy that is at least partially in a reduced form makes it possible to use operating conditions for reducing the nickel active phase that are less severe than those of the prior art, and thus it becomes possible to directly carry out the reduction step in the reactor where it is desired to carry out the hydrogenation of unsaturated or aromatic compounds.

[0068] Furthermore, the presence of copper in the catalyst enables the maintenance of good activity of the catalyst and a good service life of the catalyst when the catalyst is placed in contact with a hydrocarbon feedstock containing sulfur. In fact, compared with nickel, the copper present in the catalyst can more easily capture the sulfur-containing compounds contained in the feedstock and limit the irreversible poisoning of the active sites. The temperature rise to the desired reduction temperature is generally slow and is set, for example, at 0.1 to 10 °C / min, preferably 0.3 to 7 °C / min.

[0069] The hydrogen flow rate, expressed in L / hour / gram of catalyst precursor, is 0.01 to 100 L / hour / gram of catalyst, preferably 0.05 to 10 L / hour / gram of catalyst precursor, and more preferably 0.1 to 5 L / hour / gram of catalyst precursor.

[0070] (3. Catalyst) By the preparation method according to the present invention, a catalyst can be obtained that contains nickel and copper and a porous alumina support, wherein nickel is present in a proportion of 1% to 50% by weight of nickel element relative to the total weight of the catalyst, and copper is present in a proportion of 0.5% to 15% by weight of copper element relative to the total weight of the catalyst. The size of the nickel particles in the catalyst, measured in oxide form, is less than 5 nm.

[0071] Preferably, at least a part of nickel and copper is in the form of a nickel-copper alloy, and advantageously, it corresponds to the formula Ni x Cu y wherein x is 0.1 to 0.9 and y is 0.1 to 0.9.

[0072] Preferably, the nickel content in the copper-nickel alloy is 0.5% to 15% by weight of nickel element relative to the total weight of the catalyst, preferably 1% to 12% by weight, and more preferably 1% to 10% by weight.

[0073] The size of the nickel particles, measured in oxide form, is less than 5 nm in the catalyst, more preferably less than 4 nm, and even more preferably 3 nm or less.

[0074] The nickel content in the catalyst is preferably 1% to 50% by weight, more preferably 2% to 40% by weight, even more preferably 3% to 35% by weight, and even more preferably 5% to 25% by weight relative to the total weight of the catalyst.

[0075] 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 even more preferably 1 to 9% by weight of copper element relative to the total weight of the catalyst.

[0076] The specific surface area of the catalyst is generally 10 m 2 / g to 350 m 2 / g, preferably 25 m 2 / g to 300 m 2 / g, more preferably 40 m 2 / g to 250 m 2 / g.

[0077] The total pore volume of the catalyst is generally 0.1 to 1 mL / g, preferably 0.2 mL / g to 0.8 mL / g, and particularly preferably 0.3 mL / g to 0.7 mL / g.

[0078] The active phase of the catalyst preferably does not contain metals from Group VIB. In particular, it does not contain molybdenum or tungsten.

[0079] The catalyst (and the support used in the preparation of the catalyst) is in the form of granules, and preferably has a diameter of 0.5 to 10 mm. The granules may have any form known to those skilled in the art, for example, in the form of beads (preferably having a diameter of 1 to 8 mm), extrudates, tablets or hollow cylinders. Preferably, the catalyst (and the support used in the preparation of the catalyst) is in the form of extrudates having a diameter of 0.5 to 10 mm, preferably 0.8 to 3.2 mm, most preferably 1.0 to 2.5 mm and a length of 0.5 to 20 mm. The "diameter" of the extrudates is intended to mean the diameter of the circle circumscribed in the cross-section of these extrudates. The catalyst can advantageously be presented in the form of cylindrical, multi-lobed, three-lobed or four-lobed extrudates. Preferably, its shape is three-lobed or four-lobed. The shape of the lobes can be adjusted according to all known methods of the prior art.

[0080] (4. Support) The characteristics of the alumina referred to in this section correspond to the characteristics of the alumina before performing step a) of the preparation method according to the present invention.

[0081] The support is alumina, that is, the support contains 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. Alumina generally exhibits a crystallographic structure of the δ-, γ- or θ-alumina type, either alone or as a mixture.

[0082] The alumina support may contain impurities, for example, oxides of metals from Group IIA, Group IIIB, Group IVB, Group IIB, Group IIIA and Group 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.

[0083] The specific surface area of alumina is generally 10 m 2 / g to 400 m2 / g, preferably 30 m 2 / g to 350 m 2 / g, more preferably 50 m 2 / g to 300 m 2 / g.

[0084] The pore volume of alumina is generally 0.1 mL / g to 1.2 mL / g, preferably 0.3 mL / g to 0.9 mL / g, and most preferably 0.5 mL / g to 0.9 mL / g.

[0085] The median mesopore diameter is advantageously 3 to 25 nm, preferably 6 to 20 nm, and particularly preferably 8 to 18 nm.

[0086] (5. Selective hydrogenation method) Another subject of the present invention is a method for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, such as diolefins and / or acetylenes and / or alkenyl aromatics (also known as styrenes), contained in a hydrocarbon feedstock having a final boiling point of 300 °C or lower. This method is carried out in the presence of a catalyst obtained by the above-described preparation method, the temperature at that time is 0 °C to 300 °C, the pressure at that time is 0.1 to 10 MPa, and when this method is carried out in the liquid phase, the hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio at that time is 0.1 to 10, and the space-time velocity at that time is 0.1 to 200 h -1 or, when this method is carried out in the gas phase, the hydrogen / (polyunsaturated compound to be hydrogenated) molar ratio at that time is 0.5 to 1000, and the space-time velocity at that time is 100 to 40,000 h -1 .

[0087] For example, mono-unsaturated organic compounds such as ethylene and propylene, for example, ethylene and propylene, etc., are fundamental to the production of polymers, plastics and other chemicals with added value. These compounds are natural gas, naphtha or light oil, and are obtained from those treated by steam cracking or catalytic cracking methods. These methods are carried out at high temperatures and, in addition to the desired mono-unsaturated compounds, poly-unsaturated organic compounds such as acetylene, propadiene and methylacetylene (or propyne), 1,2-butadiene and 1,3-butadiene, vinylacetylene and ethylacetylene, and other poly-unsaturated compounds whose boiling points correspond to the C5+ fraction (hydrocarbon compounds having at least 5 carbon atoms), in particular diolefin or styrene or indene compounds are produced. These poly-unsaturated compounds are highly reactive and cause side reactions in the polymerization unit. Therefore, it is necessary to remove them before making economic use of these fractions.

[0088] Selective hydrogenation is the main treatment developed to specifically remove unwanted poly-unsaturated compounds from these hydrocarbon feedstocks. Thereby, conversion of the poly-unsaturated compounds to the corresponding alkenes or aromatics is made possible while avoiding their complete saturation and thus the formation of the corresponding alkanes or naphthenes. In the case where steam-cracked gasoline is used as the feedstock, selective hydrogenation also makes it possible to selectively hydrogenate alkenyl aromatic compounds to give aromatic compounds while avoiding hydrogenation of the aromatic rings.

[0089] The final boiling point of the hydrocarbon feedstock treated in the selective hydrogenation process is 300 °C or lower, contains at least 2 carbon atoms per molecule and contains at least one poly-unsaturated compound. The term "poly-unsaturated compound" is understood to mean a compound containing at least one acetylene functional group and / or at least one diene functional group and / or at least one alkenyl aromatic functional group.

[0090] More particularly, the feedstock is selected from the group consisting of a C2 steam cracking fraction, a C2-C3 steam cracking fraction, a C3 steam cracking fraction, a C4 steam cracking fraction, a C5 steam cracking fraction and steam cracking gasoline. Steam cracking gasoline is also known as pyrolysis gasoline or a C5+ fraction.

[0091] The C2 steam cracking fraction is advantageously used in the practice of the selective hydrogenation process according to the invention and shows, for example, the following composition: 40 wt% to 95 wt% ethylene and about 0.1 wt% to 5 wt% acetylene, the remainder being essentially ethane and methane. In some C2 steam cracking fractions, 0.1 wt% to 1 wt% C3 compounds can also be present.

[0092] The C3 steam cracking fraction is advantageously used for the practice of the selective hydrogenation process according to the invention and shows, for example, the following average composition: about 90 wt% propylene, about 1 wt% to 8 wt% propadiene and methylacetylene, the remainder being essentially propane. In some C3 fractions, 0.1 wt% to 2 wt% C2 and C4 compounds can also be present.

[0093] The C2-C3 fraction can also be advantageously used in the practice of the selective hydrogenation process according to the invention. It shows, for example, the following composition: about 0.1 wt% to 5 wt% acetylene, about 0.1 wt% to 3 wt% propadiene and methylacetylene, about 30 wt% ethylene and about 5 wt% propylene, the remainder being essentially methane, ethane and propane. This feedstock can also contain 0.1 wt% to 2 wt% C4 compounds.

[0094] The C4 steam cracking fraction is advantageously used in the practice of the selective hydrogenation process according to the invention and shows, for example, the following average weight composition: 1 wt% butane, 46.5 wt% butene, 51 wt% butadiene, 1.3 wt% vinylacetylene and 0.2 wt% butyne. In some C4 fractions, 0.1 wt% to 2 wt% C3 and C5 compounds can also be present.

[0095] The C5 steam cracking fraction is advantageously used in the implementation of the selective hydrogenation process according to the invention and, for example, has the following composition: 21% by weight of pentane, 45% by weight of pentene and 34% by weight of pentadiene.

[0096] Steam cracked gasoline or pyrolysis gasoline is advantageously used in the implementation of the selective hydrogenation process according to the invention and corresponds to a hydrocarbon fraction whose boiling point is generally between 0 and 300 °C, preferably between 10 and 250 °C. The polyunsaturated hydrocarbons to be hydrogenated present in said steam cracked gasoline are, in particular, diolefin compounds (butadiene, isoprene, cyclopentadiene, etc.), styrene compounds (styrene, α-methylstyrene, etc.) and indene compounds (indene, etc.). Steam cracked gasoline generally contains a C5-C12 fraction, but is accompanied by traces of C3, C4, C13, C14 and C15 (for example, 0.1% to 3% by weight for each of these fractions). For example, the feedstock formed from pyrolysis gasoline generally has the following composition: 5% to 30% by weight of saturated compounds (paraffins and naphthenes), 40% to 80% by weight of aromatic compounds, 5% to 20% by weight of monoolefins, 5% to 40% by weight of diolefins and 1% to 20% by weight of alkenyl aromatic compounds, the total of the compounds forming 100% by weight. It also contains 0 to 1000 ppm by weight of sulfur, preferably 0 to 500 ppm by weight of sulfur.

[0097] Preferably, the polyunsaturated hydrocarbon feedstock treated according to the selective hydrogenation process according to the invention is a C2 steam cracking fraction or a C2-C3 steam cracking fraction or steam cracked gasoline.

[0098] The selective hydrogenation method according to the present invention is targeted at removing the polyunsaturated hydrocarbons present in the feedstock to be hydrogenated without hydrogenating the mono-unsaturated hydrocarbons. For example, when the feedstock is a C2 fraction, the selective hydrogenation method is targeted at selectively hydrogenating acetylene. When the feedstock is a C3 fraction, the selective hydrogenation method is targeted at selectively hydrogenating propadiene and methylacetylene. In the case of a C4 fraction, the aim is to remove butadiene, vinylacetylene (VAC) and butyne; in the case of a C5 fraction, the aim is to remove pentadiene. When the feedstock is steam-cracked gasoline, the selective hydrogenation method is targeted at selectively hydrogenating the polyunsaturated hydrocarbons present in the feedstock to be treated, the diolefin compounds being partially hydrogenated to give monoolefins, and the compounds of styrene and indene being partially hydrogenated to give the corresponding aromatic compounds while avoiding the hydrogenation of the aromatic rings.

[0099] The technical implementation of the selective hydrogenation method is carried out, for example, by injecting the polyunsaturated hydrocarbon feedstock and hydrogen into at least one fixed-bed reactor in an upflow or downflow mode. The reactor can be of the isothermal or adiabatic type. An adiabatic reactor is preferred. The polyunsaturated hydrocarbon feedstock can advantageously be diluted by one or more reinjections at various points of the reactor located between the inlet and the outlet of the reactor of the effluent resulting from the reactor in which the selective hydrogenation reaction takes place, limiting the temperature gradient within the reactor. The technical implementation of the selective hydrogenation method according to the present invention can also advantageously be carried out by embedding at least the supported catalyst in a reactive distillation column or a reactor-exchanger or a slurry-type reactor. The flow of hydrogen can be introduced simultaneously with the feedstock to be hydrogenated and / or at one or more different points of the reactor.

[0100] The selective hydrogenation of the steam cracking fractions of C2, C2-C3, C3, C4, C5 and C5+ can be carried out in the gas phase or in the 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 can reduce the energy cost and extend the catalyst cycle period.

[0101] Generally, when the selective hydrogenation of a hydrocarbon feedstock containing a polyunsaturated compound having at least 2 carbon atoms per molecule and a final boiling point of 300 °C or lower is carried out, the temperature is 0 °C to 300 °C, and the pressure is 0.1 to 10 MPa. For the method carried out in the liquid phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.1 to 10, and the space-time velocity (defined as the volume flow rate of the feedstock to the volume of the catalyst) is 0.1 to 200 h -1 or, for the method carried out in the gas phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.5 to 1000, and the space-time velocity is 100 to 40,000 h -1 is.

[0102] In one embodiment according to the present invention, when the feedstock is steam-cracked gasoline containing a polyunsaturated compound when the selective hydrogenation method is carried out, the molar ratio of (hydrogen) / (polyunsaturated compound to be hydrogenated) is generally 0.5 to 10, preferably 0.7 to 5.0, even more preferably 1.0 to 2.0, the temperature is 0 °C to 200 °C, preferably 20 °C to 200 °C, even more preferably 30 °C to 180 °C, and the space-time velocity (HSV) is generally 0.5 to 100 h -1 preferably 1 to 50 h -1 and the pressure is generally 0.3 to 8.0 MPa, preferably 1.0 to 7.0 MPa, even more preferably 1.5 to 4.0 MPa.

[0103] More preferably, when the feedstock is steam-cracked gasoline containing a polyunsaturated compound during the selective hydrogenation process, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) is 0.7 to 5.0, the temperature is 20°C to 200°C, and the space-time velocity (HSV) is generally 1 to 50 h -1 and the pressure is 1.0 to 7.0 MPa.

[0104] Even more preferably, when the feedstock is steam-cracked gasoline containing a polyunsaturated compound during the selective hydrogenation process, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) is 1.0 to 2.0, the temperature is 30°C to 180°C, and the space-time velocity (HSV) is generally 1 to 50 h -1 and the pressure is 1.5 to 4.0 MPa.

[0105] The hydrogen flow rate is adjusted to make available an amount of hydrogen sufficient to theoretically hydrogenate all of the polyunsaturated compound and to maintain excess hydrogen at the reactor outlet.

[0106] In another embodiment according to the present invention, when the feedstock is a C2 steam-cracked fraction and / or a C2-C3 steam-cracked fraction containing a polyunsaturated compound during the selective hydrogenation process, the molar ratio of (hydrogen) / (polyunsaturated compound to be hydrogenated) is generally 0.5 to 1000, preferably 0.7 to 800, the temperature is 0°C to 300°C, preferably 15°C to 280°C, and the space-time velocity (HSV) is generally 100 to 40,000 h -1 , preferably 500 to 30,000 h -1 and the pressure is generally 0.1 to 6.0 MPa, preferably 0.2 to 5.0 MPa.

[0107] (6. Method for Hydrogenation of Aromatic Compounds) Another subject of the present invention is a method for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of 650 °C or lower, generally 20 °C to 650 °C, preferably 20 °C to 450 °C. The hydrocarbon feedstock containing at least one aromatic or polyaromatic compound can be selected from the following petroleum or petrochemical fractions: reformed oil from catalytic reforming, kerosene, light gas oil, heavy gas oil, cracked distillate, such as FCC recycle oil, coking unit gas oil or hydrocracked distillate.

[0108] In the hydrocarbon feedstock treated in the hydrogenation process according to the present invention, the content of aromatic or polyaromatic compounds is generally 0.1 wt% to 80 wt%, preferably 1 wt% to 50 wt%, particularly preferably 2 wt% to 35 wt%, and the percentage is 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 aromatic compounds (polyaromatic compounds) having several aromatic rings, such as naphthalene.

[0109] 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.

[0110] The technical implementation of the method for the hydrogenation of aromatic or polyaromatic compounds is carried out, for example, by the injection of a hydrocarbon feedstock and hydrogen as an upflow or downflow into at least one fixed-bed reactor. The reactor can be of the isothermal type or the adiabatic type. An adiabatic reactor is preferred. The hydrocarbon feedstock can advantageously be diluted by one or more reinjections at various points of the reactor located between the inlet and the outlet of the reactor of the effluent resulting from the reactor in which the reaction for the hydrogenation of the aromatic compound takes place, limiting the temperature gradient in the reactor. The flow of hydrogen can be introduced simultaneously with the feedstock to be hydrogenated and / or at one or more different points of the reactor. The technical implementation of the method for the hydrogenation of aromatic compounds according to the invention can advantageously also be carried out by embedding at least the supported catalyst in a reactive distillation column or a reactor-exchanger or a slurry-type reactor. The flow of hydrogen can be introduced simultaneously with the feedstock to be hydrogenated and / or at one or more different points of the reactor.

[0111] The hydrogenation of aromatic or polyaromatic compounds can be carried out in the gas phase or the liquid phase, preferably the liquid phase. Generally, the temperature at which the hydrogenation of aromatic or polyaromatic compounds is carried out is 30°C to 350°C, preferably 50°C to 325°C, the pressure at that time is 0.1 to 20 MPa, preferably 0.5 to 10 MPa, the molar ratio of hydrogen / (aromatic compound to be hydrogenated) at that time is 0.1 to 10, and the space-time velocity at that time is 0.05 to 50 h -1 , preferably 0.1 to 10 h -1 and the hydrocarbon feedstock contains an aromatic or polyaromatic compound, and the final boiling point of the hydrocarbon feedstock is 650°C or lower, generally 20°C to 650°C, preferably 20°C to 450°C.

[0112] The hydrogen flow rate is adjusted to make available an amount of hydrogen sufficient to theoretically hydrogenate all of the aromatic compound and to maintain an excess of hydrogen at the reactor outlet.

[0113] The conversion rate of the aromatic or polyaromatic compound is generally more than 20 mol%, preferably more than 40 mol%, more preferably more than 80 mol%, and particularly preferably more than 90 mol% of the aromatic or polyaromatic compound contained in the hydrocarbon feedstock. The conversion rate is calculated by dividing the difference in the total number of moles of the aromatic or polyaromatic compound between the hydrocarbon feedstock and the product by the total number of moles of the aromatic or polyaromatic compound in the hydrocarbon feedstock.

[0114] According to a specific modification of the method according to the present invention, a method for the hydrogenation of benzene in a hydrocarbon feedstock, for example, reformed oil produced from a catalytic reforming unit, is carried out. The benzene content in the hydrocarbon feedstock is generally 0.1 wt% to 40 wt%, preferably 0.5 wt% to 35 wt%, and particularly preferably 2 wt% to 30 wt%, and the weight percentage is based on the total weight of the hydrocarbon feedstock.

[0115] The sulfur or chlorine content of the feedstock is generally less than 10 wt ppm, preferably less than 2 wt ppm, in terms of the weight of sulfur or chlorine, respectively.

[0116] The hydrogenation of benzene contained in the hydrocarbon feedstock can be carried out in the gas phase or the liquid phase, preferably in the liquid phase. When it is carried out in the liquid phase, a solvent can be present, for example, cyclohexane, heptane or octane. Generally, the temperature at which the hydrogenation of benzene is carried out is 30 to 250 °C, preferably 50 to 200 °C, more preferably 80 to 180 °C, the pressure at that time is 0.1 to 10 MPa, preferably 0.5 to 4 MPa, the molar ratio of hydrogen / (benzene) at that time is 0.1 to 10, and the space-time velocity at that time is 0.05 to 50 h -1 preferably 0.5 to 10 h -1 is.

[0117] The conversion of benzene is generally more than 50 mol%, preferably more than 80 mol%, more preferably more than 90 mol%, and particularly preferably more than 98 mol%.

[0118] The present invention will now be illustrated through the following examples, which are in no way limiting.

[0119] (Example) For all the catalysts mentioned in the examples described below, the support is alumina A, with a specific surface area of 180 m 2 / g, a pore volume of 0.7 mL / g and a mesopore median diameter of 10 nm.

[0120] (Example 1: Preparation of aqueous solution S1 of the first Ni precursor having the first organic compound) The aqueous solution S1 is prepared by dissolving 58 g of nickel nitrate (NiNO3 supplied by Strem Chemicals®) and 14.35 g of malonic acid (CAS 141 - 82 - 2; supplier Fluka®) in 42 ml of distilled water by volume. The solution is heated to 60 °C to facilitate the dissolution of nickel nitrate. The additive / Ni molar ratio is fixed at 0.4 mol / mol. Solution S1 is obtained.

[0121] (Example 2: Preparation of aqueous solution S2 of the precursor of NiCu alloy (5 wt% Ni) without the second organic compound) The aqueous solution (solution S2) of the precursor of the NiCu alloy used for the preparation of the catalyst containing NiCu is prepared by dissolving 14.5 g of nickel nitrate (NiNO3, supplier Strem Chemicals®) in 13 ml of distilled water by volume. A solution with a Ni concentration of 116.6 g of Ni per liter of solution volume is obtained. The copper nitrate precursor is then added such that the Ni / Cu molar ratio is 1.

[0122] Solution S2 is obtained. Thereby, it becomes possible to introduce the precursor of the NiCu alloy. The weight content of Ni relative to the final catalyst is 5 wt% relative to the total weight of the catalyst.

[0123] (Example 3: Preparation of aqueous solution S3 of the precursor of NiCu alloy and the second organic compound (5 wt% Ni)) The preparation of an aqueous solution (solution S3) of a NiCu alloy precursor used in the preparation of a catalyst containing NiCu is carried out by dissolving 14.5 g of nickel nitrate (NiNO3, supplier Strem Chemicals®) in 13 mL of distilled water by volume. A solution is obtained in which the Ni concentration is 116.6 g of Ni per liter of solution volume. The copper nitrate precursor is then added so that the Ni / Cu molar ratio is 1. Malonic acid is also added to the solution so that it has an additive / Ni molar ratio of 0.90 mol / mol.

[0124] Solution S3 is obtained. Thereby, it becomes possible to introduce the precursor of the NiCu alloy, and the weight content of Ni relative to the final catalyst is 5% by weight relative to the total weight of the catalyst.

[0125] (Example 4: Preparation of Catalyst A (not in accordance with the present invention - without a second organic compound)) 10 g of alumina A is dry-impregnated with 7.1 mL of solution S1. The obtained catalyst precursor is subsequently dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst. Next, dry impregnation with 10 mL of solution S2 prepared in Example 2 is carried out by dropping it. The solid thus obtained is subsequently dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst.

[0126] A catalyst A is obtained that contains 24% by weight of nickel element (including 5% by weight of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst A thus obtained are given in Table 1 below.

[0127] (Example 5: Preparation of Catalyst B (not in accordance with the present invention - without a second organic compound)) 10 g of alumina A is dry-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g catalyst. This intermediate catalyst is then dry-re-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g catalyst. Next, dry impregnation of 10 ml of solution S2 prepared in Example 2 is carried out by dropping it. The solid thus obtained is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g catalyst.

[0128] A catalyst B is obtained that contains 27% by weight of nickel element (containing 5% by weight of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst B thus obtained are given in Table 1 below.

[0129] (Example 6: Preparation of catalyst C (conforming to the present invention)) 10 g of alumina A is dry-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g catalyst. Next, dry impregnation of 10 mL of solution S3 prepared in Example 3 is carried out by dropping it. The ratio of the molar ratio of the second organic compound / Ni (NiCu solution, solution S2) to the molar ratio of the first organic compound / Ni (active Ni solution S1) is 2.25. The solid thus obtained is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g catalyst.

[0130] A catalyst C is obtained that contains 24% by weight of nickel element (containing 5% by weight of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst C thus obtained are given in Table 1 below.

[0131] (Example 7: Preparation of Catalyst D (in accordance with the present invention - double impregnation)) 10 g of alumina A is dry-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst. This intermediate catalyst is then dry-re-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst. Then, dry impregnation of 10 mL of solution S3 prepared in Example 3 is carried out by dropping it. The ratio of the molar ratio of the second organic compound / Ni (NiCu solution, S2 solution) to the molar ratio of the first organic compound / Ni (active Ni solution S1) is 2.25. The solid thus obtained is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst.

[0132] A catalyst D is obtained which contains 27% by weight of nickel element (containing 5% by weight of nickel element in the NiCu alloy) relative to the total weight of the catalyst. The characteristics of the catalyst D thus obtained are given in Table 1 below.

[0133] (Example 8: Preparation of Catalyst E (not in accordance with the present invention - without NiCu and the second organic compound)) 10 g of alumina A is dry-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst. This intermediate catalyst is then dry-re-impregnated with 7.1 mL of solution S1. The resulting catalyst precursor is then dried in an oven at 120 °C for 12 hours and then calcined at 450 °C for 2 hours under a flow of dry air at 1 L / h / g of catalyst.

[0134] A catalyst E containing 22% by weight of nickel element relative to the total weight of the catalyst is obtained. The characteristics of the catalyst E thus obtained are given in Table 1 below.

[0135] [Table 1]

[0136] (Example 9: Evaluation of Characteristics) The amount of alloy obtained after the calcination step and then the reduction step was determined by X-ray diffraction (XRD) analysis on a sample of the catalyst in powder form.

[0137] The amount of nickel in metallic form obtained after the reduction step was determined by X-ray diffraction (XRD) analysis on a sample of the catalyst in powder form. During the reduction step and throughout the duration of the characteristic evaluation by XRD, the catalyst was never returned to the outside air. The diffraction pattern was obtained by radiation crystal analysis using a diffractometer with the conventional powder method using copper Kα1 radiation (λ = 1.5406 Å).

[0138] The degree of reduction was calculated by calculating the area of the line of Ni located at about 52° 2θ over the entire diffraction pattern of each sample of the analyzed catalyst, and then subtracting the signal under the line at 52° due to alumina that exists as soon as the ambient temperature is reached. 0 This was done by subtracting the signal under the line at 52° due to alumina that exists as soon as the ambient temperature is reached.

[0139] Table 2 below summarizes the degree of reduction or the content of nickel metal Ni° (expressed as % by weight relative to the total weight of "active" Ni that does not form an alloy) for all catalysts A - E characterized by XRD after a reduction step at 170 °C for 190 minutes under a hydrogen stream. These values were compared with the degree of reduction obtained for catalyst E (Ni alone) after a conventional reduction step (i.e., at a temperature of 400 °C for 15 hours under a hydrogen stream).

[0140] Alumina in the form of delta and theta, as well as large lines of CuO and NiO, are detected on all copper-nickel-containing catalysts at ambient temperature after firing.

[0141] Ni 0.76 Cu 0.24 Lines corresponding to the alloy in the form of are further detected after reduction.

[0142] The degree of reducibility, and thus Ni 0 To evaluate the formation of, subtract the signal under the 52° line due to alumina, which is present as soon as ambient temperature is reached, from all diffractograms to measure the area of the Ni 0 line located at approximately 52° 2θ. It is thus possible to determine the relative percentage (%) of Ni 0 crystallized after reduction.

[0143]

Table 2

[0144] In the case of catalyst E (22% Ni alone / alumina), the reduction degree of nickel is 0% after the reduction treatment under the same hydrogen as in the cases of catalysts A, B, C, and D. To make the reduction of nickel oxide to Ni about 80%, it is necessary to reduce catalyst E at 400 °C.

[0145] (Example 10: Catalyst test: Performance in the selective hydrogenation of a mixture containing styrene and isoprene (A HYD1 )) Catalysts A - E described in the above examples are tested for the reaction for the selective hydrogenation of a mixture containing styrene and isoprene.

[0146] The composition of the feedstock to be selectively hydrogenated is as follows: 8 wt% styrene (supplier Sigma Aldrich®, purity 99%), 8 wt% isoprene (supplier Sigma Aldrich®, purity 99%) and 84 wt% n - heptane (solvent) (supplier VWR®, purity > 99% Chromanorm HPLC). This composition corresponds to the initial composition of the reaction mixture. This mixture of model molecules is representative of pyrolysis gasoline.

[0147] The selective hydrogenation reaction is carried out in a 500 mL stainless - steel autoclave. This stainless - steel autoclave is equipped with a magnetic - drive mechanical stirrer and can be operated at a maximum pressure of 100 bar (10 MPa) and a temperature range of 5 °C to 200 °C.

[0148] 214 mL of n - heptane (supplier VWR®, purity > 99% Chromanorm HPLC) and 3 mL of the 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 in - situ reduced for 90 minutes at 170 °C (with a temperature - rising gradient of 1 °C / min) under a hydrogen flow of 1 L / h / g for catalysts A - E (here, this corresponds to step f of the preparation method according to the present invention in one embodiment). The autoclave is then brought to a test temperature equal to 30 °C. At time t = 0, approximately 30 g of a mixture containing styrene, isoprene, n - heptane, pentanethiol and thiophene is introduced into the autoclave. The reaction mixture has the above - mentioned composition and stirring is started at 1600 rpm. The pressure inside the autoclave is kept constant at 35 bar (3.5 MPa) using a storage cylinder located upstream of the reactor.

[0149] Another test was carried out for catalyst E, and the catalyst reduction temperature was 400 °C for 15 hours.

[0150] The progress of the reaction is monitored by taking samples from the reaction medium at regular time intervals: styrene is hydrogenated to give ethylbenzene, the aromatic ring is not hydrogenated, and isoprene is hydrogenated to give methylbutene. If the reaction is allowed to proceed for longer than necessary, the methylbutene is then hydrogenated to give isopentane. Hydrogen consumption is also monitored over time by the decrease in pressure in a storage cylinder located upstream of the reactor. Catalyst activity is expressed as the number of moles of H2 consumed per minute and per gram of Ni weight.

[0151] The catalyst activities measured for Catalysts A - E are reported in Table 3 below. They are related to the catalyst activity (A HYD1 ) measured for Catalyst E prepared under conventional reduction conditions (under a hydrogen flow, at a temperature of 400 °C for 15 hours).

[0152] (Example 11: Catalyst Test: Performance in the Hydrogenation of Toluene (A HYD2 )) Catalysts A - E described in the above examples are also tested for the reaction for the hydrogenation of toluene. The selective hydrogenation reaction is carried out in the same autoclave as described in Example 10.

[0153] 214 mL of n - heptane (supplier VWR®, purity > 99% Chromanorm HPLC) and 3 mL of the 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 90 minutes at 170 °C under a hydrogen flow of 1 L / h / g (temperature - rising gradient of 1 °C / min) for catalysts A - E (this corresponds to step f of the preparation method according to the invention in one embodiment here). After the addition of 216 mL of n - heptane (supplier VWR®, purity > 99% Chromanorm HPLC), the autoclave is closed, purged, then pressurized under 35 bar (3.5 MPa) of hydrogen and brought to a test temperature equal to 80 °C. At time t = 0, approximately 26 g of toluene (supplier SDS®, purity > 99.8%) is introduced into the autoclave (the initial composition of the reaction mixture is 6 wt% toluene / 94 wt% n - heptane), and stirring is started at 1600 rpm. The pressure inside the autoclave is kept constant at 35 bar (3.5 MPa) using a storage cylinder located upstream of the reactor.

[0154] 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 decrease in pressure in the storage cylinder located upstream of the reactor. The catalytic activity is expressed as the number of moles of H2 consumed per minute and per gram of Ni by weight.

[0155] The catalytic activities measured for catalysts A - E are reported in Table 3 below. They are related to the catalytic activity (A HYD2 ) measured for catalyst E prepared under conventional reduction conditions (under a hydrogen flow, at a temperature of 400 °C for 15 hours).

[0156]

Table 3

[0157] These results clearly show a significant improvement in the performance of catalysts C and D obtained by the preparation method according to the present invention, compared to catalysts A, B, and E that do not conform to the present invention. In the case of catalysts A and B, nickel oxide is reduced by 90% at 170 °C and has particles grown during the impregnation step of NiCu without the presence of a second organic compound. Catalyst E has a reduced activity due to the absence of NiCu, and thus the reducibility of NiO at 170 °C is substantially zero. Catalysts C and D retain small nickel particles by the addition of malonic acid (the second organic compound) during the post-treatment addition of NiCu, compared to the addition of the precursor of the nickel active phase. HYD1 and A HYD2 ​

Claims

Claim 1 A method for preparing a catalyst comprising nickel and copper and a porous alumina support, wherein the nickel is present in a proportion of 1% to 50% by weight of nickel element relative to the total weight of the catalyst, the copper is present in a proportion of 0.5% to 15% by weight of copper element relative to the total weight of the catalyst, the size of the nickel particles in the catalyst, measured in the form of an oxide, is less than 5 nm, and the method comprises at least the following steps: a) contacting the alumina support with at least one solution containing at least one first nickel precursor and at least one first organic compound containing at least one carboxylic acid functional group; obtaining a first catalyst precursor; b) drying the first catalyst precursor obtained at the end of step a) at a temperature below 250 °C and then calcining the dried first catalyst precursor at a temperature of 250 °C to 550 °C; obtaining a calcined catalyst precursor; c) contacting the calcined catalyst precursor obtained at the end of step b) with at least one solution containing at least one second nickel precursor, at least one copper precursor, and at least one second organic compound containing at least one carboxylic acid functional group; obtaining a second catalyst precursor; d) drying the second catalyst precursor obtained at the end of step c) at a temperature below 250 °C. Claim 2 The method according to claim 1, wherein the molar ratio between the organic compound introduced in step a) and the nickel element also introduced in step a) is 0.01 to 5.0 mol / mol. Claim 3 The method according to claim 1 or 2, wherein the molar ratio between the organic compound introduced in step c) and the nickel element also introduced in step c) is 0.02 to 5 mol / mol. Claim 4 The method according to any one of claims 1 to 3, wherein the molar ratio between the nickel introduced between steps a) and c) and the copper introduced in step c) is 0.5 to 5 mol / mol. Claim 5 The method according to any one of claims 1 to 4, wherein the ratio between the molar ratio between the second organic compound and nickel introduced in step c) and the molar ratio between the first organic compound and nickel introduced in step a) is greater than 1.

5. Claim 6 The method according to any one of claims 1 to 5, wherein steps a) and b) are carried out at least twice before carrying out step c).

7. The method according to any one of claims 1 to 6, wherein the first organic compound in step a) and the second organic compound in step c) are selected from oxalic acid, malonic acid, glycolic acid, lactic acid, tartronic acid, citric acid, tartaric acid, pyruvic acid and levulinic acid.

8. The method according to any one of claims 1 to 7, wherein the first organic compound in step a) and the second organic compound in step c) are the same.

9. The method according to any one of claims 1 to 8, wherein the copper precursor is selected from copper acetate, copper acetylacetonate, copper nitrate, copper sulfate, copper chloride, copper bromide, copper iodide and copper fluoride.

10. The method according to any one of claims 1 to 9, wherein the first nickel precursor and / or the second nickel precursor is nickel nitrate, nickel chloride, nickel acetate or nickel hydroxycarbonate.

11. The method according to any one of claims 1 to 10, further comprising step e), wherein the catalyst obtained at the end of step d) is calcined at a temperature of 250 °C to 550 °C.

12. The method according to any one of claims 1 to 11, further comprising step f), wherein the catalyst obtained at the end of step d) and optionally at the end of step e) is reduced by contacting it with a reducing gas at a temperature of 150 °C or higher and lower than 250 °C.

13. A catalyst obtained by the method according to any one of claims 1 to 12, wherein the catalyst comprises nickel and copper and a porous alumina support, the nickel is present in a proportion of 1% to 50% by weight of nickel element relative to the total weight of the catalyst, the copper is present in a proportion of 0.5% to 15% by weight of copper element relative to the total weight of the catalyst, and the size of the nickel particles in the catalyst, measured in oxide form, is less than 5 nm.

14. A method for the selective hydrogenation of a polyunsaturated compound containing at least 2 carbon atoms per molecule, which is contained in a hydrocarbon feedstock having a final boiling point of 300 °C or lower, the method being carried out in the presence of a catalyst according to claim 13 or a catalyst obtained by the preparation method according to any one of claims 1 to 12, the temperature at that time being 0 °C to 300 °C, the pressure at that time being 0.1 to 10 MPa, and when the method is carried out in the liquid phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.1 to 10, and the space-time velocity at that time is 0.1 to 200 h －１ -1, or when the method is carried out in the gas phase, the molar ratio of hydrogen / (polyunsaturated compound to be hydrogenated) at that time is 0.5 to 1000, and the space-time velocity at that time is 100 to 40,000 h －１ -1, the method.

15. A process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon feedstock having a final boiling point of 650 °C or lower, said process being carried out in the gas phase or in the liquid phase, in the presence of the catalyst according to claim 13 or the catalyst obtained by the preparation method according to any one of claims 1 to 12, the temperature at that time being 30 to 350 °C, the pressure at that time being 0.1 to 20 MPa, the molar ratio of hydrogen / (aromatic compound to be hydrogenated) at that time being 0.1 to 10, and the space velocity at that time being 0.05 to 50 h －１ A process as described above.

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