FR3091658A1 - Process for the preparation of an aromatic hydrogenation catalyst comprising a step of forming an NiCu alloy in post-impregnation - Google Patents

Abstract

Process for preparing a catalyst for the hydrogenation of aromatic or polyaromatic compounds comprising nickel, copper, and a support comprising at least one refractory oxide, comprising the following steps: bringing the catalyst precursor into contact with a solution comprising a nickel precursor; - drying the catalyst precursor at a temperature below 250 ° C; - Contacting the support with a solution containing at least one copper precursor and one nickel precursor; - step of drying the catalyst precursor at a temperature below 250 ° C; - reduction of the catalyst precursor by bringing said precursor into contact with a reducing gas at a temperature between 150 and 250 ° C.

Description

Process for the preparation of a catalyst for the hydrogenation of aromatics comprising a step of forming a NiCu alloy in post-impregnation

The present invention relates to a process for the preparation of a supported metal catalyst, comprising nickel and copper, intended particularly for the hydrogenation of at least one aromatic or polyaromatic compound contained in a hydrocarbon charge.

State of the art

Catalysts for the hydrogenation of aromatic compounds are generally based on metals from group VIII of the periodic table of elements, such as nickel. The metal is in the form of nanometric metallic particles deposited on a support which can be a refractory oxide. The group VIII metal content, the possible presence of a second metallic element, the size of the metal particles and the distribution of the active phase in the support as well as the porous nature and distribution of the support are parameters which can have a importance on catalyst performance.

The rate of the hydrogenation reaction is governed by several criteria, such as the diffusion of the reactants towards the surface of the catalyst (external diffusional limitations), the diffusion of the reactants into the pores of the support towards the active sites (internal diffusional limitations) 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.

The promotion of nickel-based catalysts has frequently been proposed in order to improve the performance in hydrogenation of unsaturated hydrocarbons. For example, the promotion of nickel-based catalysts has frequently been proposed in order to improve performance in selective hydrogenation. By way of illustration, US patent 5,208,405 discloses a catalyst based on nickel and silver for the selective hydrogenation of C4-C10 diolefins. On the other hand, it is known to promote nickel, present mainly, with group IB metals, in particular gold (FR 2,949,077) or tin (FR 2,949,078). Document FR 3,011,844 discloses a catalyst for the implementation of a selective hydrogenation process comprising a support and an active metallic phase deposited on the support, the active metallic phase comprising copper and at least one metal or cobalt metal. in a Cu:(Ni and/or Co) molar ratio greater than 1.

Furthermore, prior to the use of such catalysts and their implementation in a hydrogenation process, a step of reducing treatment in the presence of a reducing gas is carried out so as to obtain a catalyst comprising an active phase at least partially in metallic form. This treatment activates the catalyst and forms metal particles. This treatment can be carried out in-situ or ex-situ, i.e. after or before loading the catalyst into the hydrogenation reactor.

Objects of the invention

Continuing its research in the field of hydrogenating catalysts, the Applicant has now surprisingly discovered that it is possible to prepare catalysts which are particularly active in the hydrogenation of aromatic compounds, by carrying out a specific preparation process in which an alloy is formed based on nickel and copper on the support before depositing the precursor of the active phase (based on nickel) of the catalyst on the support.

Without wishing to be bound by any theory, it has been observed by the Applicant that during the preparation of the catalyst, the performance of a step of bringing the support into contact with a solution containing simultaneously a metal precursor based on copper and a metal precursor based on nickel followed by a stage of drying and reduction in the presence of a reducing gas at low temperature (between 150°C and 250°C) makes it possible to obtain a nickel-copper alloy (in the form reduced) which unexpectedly makes it possible to greatly improve the reducibility of the active phase of nickel on the support, said active phase of nickel being supplied for the most part in a step prior to that of bringing said support into contact with said solution containing simultaneously a metal precursor of copper and nickel. The preparation process according to the invention thus makes it possible to carry out a stage of reduction of the metallic elements in the presence of a reducing gas at lower temperatures and shorter reaction times than those commonly used in the prior art. Advantageously, the use of less severe operating conditions than in the prior art makes it possible to carry out the reduction step directly within the reactor in which it is desired to carry out the selective hydrogenation of polyunsaturated cuts. Furthermore, the presence of copper in the catalyst makes it possible to maintain good activity and a longer life of the catalyst when the latter is brought into contact with a hydrocarbon feed comprising sulfur, in particular in the aromatic hydrocarbon cuts. Indeed, compared to nickel, the copper present in the catalyst more easily captures the sulfur compounds included in the charge, which limits the irreversible poisoning of the active sites.

The subject of the present invention is a process for the preparation of a catalyst for the hydrogenation of aromatic or polyaromatic compounds comprising a metal active phase based on nickel, at a rate of 10 and 65% by weight of nickel element relative to the total weight of the catalyst, and based on copper, in an amount of 0.5 to 15% by weight of copper element relative to the total weight of the catalyst, and a support comprising at least one refractory oxide chosen from silica, alumina and silica -alumina, which process comprises the following steps:

a) a step of bringing said support into contact with a solution comprising at least one nickel precursor is carried out;

b) at least one step of drying the catalyst precursor is carried out at the end of step a) at a temperature below 250° C.;

c) optionally, heat treatment of the catalyst precursor obtained at the end of step b) is carried out at a temperature of between 250 and 1000° C., in the presence or absence of water;

d) a step is carried out for bringing the catalyst precursor obtained at the end of step b), optionally at the end of step c), into contact with at least one solution containing at least one copper precursor and a nickel precursor at a nickel concentration desired to obtain on the final catalyst a content of between 0.5 and 15% by weight of nickel element relative to the total weight of the final catalyst;

e) at least one stage of drying the catalyst precursor is carried out at the end of stage d) at a temperature below 250° C.;

f) optionally, heat treatment of the catalyst precursor obtained at the end of step e) is carried out at a temperature of between 250 and 1000° C., in the presence or absence of water;

g) reducing the catalyst precursor from step e), optionally step f), by bringing said catalyst precursor into contact with a reducing gas at a temperature between 150 and 250°C.

Advantageously, in step d) the molar ratio between nickel and copper is between 0.5 and 5, preferably between 0.7 and 4.5, more preferably between 0.9 and 4.

Preferably, step g) is carried out at a temperature between 160 and 230°C.

More preferably, step g) is carried out at a temperature between 170 and 220°C.

Advantageously, step g) is carried out between 10 minutes and 110 minutes.

In one embodiment according to the invention, the method further comprises a step of passivation of the catalyst precursor by a sulfur compound after step g) of reduction.

Advantageously, the passivation step is carried out at a temperature of between 20 and 350° C. for 10 to 240 minutes.

Preferably, said sulfur compound is chosen from thiophene, thiophane, dimethylsulphide, diethylsulphide, dipropylsulphide, propylmethylsulphide, di-thio-di-ethanol.

Advantageously, the copper precursor supplied during step d) is chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulphate, copper chloride, copper bromide, copper iodide or copper fluoride.

More preferably, the copper precursor is copper nitrate.

Preferably, the reducing gas of step g) is dihydrogen.

Advantageously, the hydrogen flow rate, expressed in L/hour/gram of catalyst precursor, is between 0.01 and 100 L/hour/gram of catalyst precursor.

Preferably, the nickel precursor supplied during step a) and/or d) is chosen from nickel nitrate, nickel carbonate or nickel hydroxide.

Another object according to the invention relates to a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a charge of hydrocarbons having a final boiling point less than or equal to 650° C., said process being carried out in phase gaseous or in the liquid phase, at a temperature between 30 and 350°C, at a pressure between 0.1 and 20 MPa, at a hydrogen/(aromatic compounds to be hydrogenated) molar ratio between 0.1 and 10 and at a VVH hourly volume rate of between 0.05 and 50 h ^-1 , in the presence of a catalyst obtained according to the preparation process according to the invention.

Another object according to the invention relates to a process for the preparation of a catalyst for the hydrogenation of aromatic or polyaromatic compounds comprising nickel, in an amount of 10 and 65% by weight of nickel element relative to the total weight of the catalyst, copper , at a rate of 0.5 to 15% by weight of copper element relative to the total weight of the catalyst, and a support comprising at least one refractory oxide chosen from silica, alumina and silica-alumina, which process comprises the following steps :

a) a step of bringing said support into contact with a solution comprising at least one nickel precursor is carried out;

b) at least one step of drying the catalyst precursor is carried out at the end of step a) at a temperature below 250° C.;

c) optionally, heat treatment of the catalyst precursor obtained at the end of step b) is carried out at a temperature of between 250 and 1000° C., in the presence or not of water;

d) a step is carried out for bringing the catalyst precursor obtained at the end of step b), optionally at the end of step c), into contact with at least one solution containing at least one copper precursor at a rate of 0.5 to 15% by weight of copper element relative to the total weight of the final catalyst and at least one nickel precursor, the molar ratio between nickel and copper being between 0.5 and 5;

e) at least one stage of drying the catalyst precursor is carried out at the end of stage d) at a temperature below 250° C.;

f) optionally, heat treatment of the catalyst precursor obtained at the end of step e) is carried out at a temperature of between 250 and 1000° C., in the presence or not of water;

g) reducing the catalyst precursor from step e), optionally step f), by bringing said catalyst precursor into contact with a reducing gas at a temperature between 150 and 250°C.

Detailed description of the invention

1. Definitions

In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief D.R. Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

The degree of reduction (TR) of a metal M contained in the catalyst is defined as being the percentage of said metal M reduced after the step of reducing said catalyst. The reduction rate (TR) corresponds to the ratio between the quantity of reduced metal (M1) and the quantity of theoretically reducible metal present on the catalyst measured by Fluorescence X (M2), i.e. TR (%) = (M1/M2)x100 . In the context of the present invention, the rate of reduction of nickel (Ni) was measured by X-ray diffraction analysis (XRD or “ X-ray diffraction ” according to the English terminology). The description of the method for measuring the quantity of reducible metal on oxide catalysts is explained later in the description (cf. examples section).

By the specific surface of the catalyst or of the support used for the preparation of the catalyst according to the invention is meant the specific surface B.E.T. determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the periodical “The Journal of American Society”, 60, 309, (1938).

In this application, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open-ended and does not exclude other non-recited material. It is understood that the term “include” includes the exclusive and closed term “consist”.

By “macropores”, we mean pores whose opening is greater than 50 nm.

By "mesopores", we mean pores whose opening is between 2 nm and 50 nm, limits included.

By “micropores”, we mean pores whose opening is less than 2 nm.

By total pore volume of the catalyst or of the support used for the preparation of the catalyst according to the invention is meant the volume measured by intrusion with a mercury porosimeter according to the ASTM D4284-83 standard at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne/cm and a contact angle of 140°. The wetting angle was taken as equal to 140° by following the recommendations of the work “Engineering techniques, treatise on analysis and characterization”, pages 1050-1055, written by Jean Charpin and Bernard Rasneur.

In order to obtain better precision, the value of the total pore volume corresponds to the value of the total pore volume measured by intrusion with a mercury porosimeter measured on the sample minus the value of the total pore volume measured by intrusion with a mercury porosimeter measured on the same sample for a pressure corresponding to 30 psi (about 0.2 MPa).

The volume of macropores and mesopores is measured by mercury intrusion porosimetry according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne/cm and a contact angle of 140°. The value from which the mercury fills all the intergranular voids is fixed at 0.2 MPa, and it is considered that beyond that the mercury penetrates into the pores of the sample.

The macroporous volume of the catalyst or of the support used for the preparation of the catalyst according to the invention is defined as being the cumulative volume of mercury introduced at a pressure of between 0.2 MPa and 30 MPa, corresponding to the volume contained in the pores of diameter apparent greater than 50 nm.

The mesoporous volume of the catalyst or of the support used for the preparation of the catalyst according to the invention is defined as being the cumulative volume of mercury introduced at a pressure of between 30 MPa and 400 MPa, corresponding to the volume contained in the pores of apparent diameter included between 2 and 50 nm.

The volume of the micropores is measured by nitrogen porosimetry. The quantitative analysis of the microporosity is carried out using the "t" method (method of Lippens-De Boer, 1965) which corresponds to a transformation of the initial adsorption isotherm as described in the work "Adsorption by powders and porous solids. Principles, methodology and applications” written by F. Rouquérol, J. Rouquérol and K. Sing, Academic Press, 1999.

The median mesoporous diameter is also defined as being the diameter such that all the pores, among all the pores constituting the mesoporous volume, of size less than this diameter constitute 50% of the total mesoporous volume determined by intrusion with a mercury porosimeter.

The median macroporous diameter is also defined as being the diameter such that all the pores, among all the pores constituting the macroporous volume, of size less than this diameter constitute 50% of the total macroporous volume determined by intrusion with a mercury porosimeter.

2. Detailed Description

Catalyst Preparation Process

According to the invention, the process for preparing a catalyst for the hydrogenation of aromatic or polyaromatic compounds comprising a metallic active phase based on nickel, at a rate of 10 and 65% by weight of nickel element relative to the total weight of the catalyst , and based on copper, in an amount of 0.5 to 15% by weight of copper element relative to the total weight of the catalyst, and a support comprising at least one refractory oxide chosen from silica, alumina and silica- alumina, includes the following steps:

a) a step of bringing said support into contact with a solution comprising at least one nickel precursor is carried out;

b) at least one step of drying the catalyst precursor is carried out at the end of step a) at a temperature below 250° C.;

c) optionally, heat treatment of the catalyst precursor obtained at the end of step b) is carried out at a temperature of between 250 and 1000° C., in the presence or not of water;

d) a step is carried out for bringing the catalyst precursor obtained at the end of step b), optionally at the end of step c), into contact with at least one solution containing at least one copper precursor and a nickel precursor at a nickel concentration desired to obtain on the final catalyst a content of between 0.5 and 15% by weight of nickel element relative to the total weight of the final catalyst;

e) at least one stage of drying the catalyst precursor is carried out at the end of stage d) at a temperature below 250° C.;

f) optionally, heat treatment of the catalyst precursor obtained at the end of step e) is carried out at a temperature of between 250 and 1000° C., in the presence or absence of water;

g) reducing the catalyst precursor from step e), optionally step f), by bringing said catalyst precursor into contact with a reducing gas at a temperature between 150 and 250°C.

h) optionally, a passivation step is carried out with a sulfur compound after the reducing treatment step g).

Steps a) to h) of said preparation process are described in detail below.

Step a) Bringing the support into contact with a solution comprising a nickel precursor

The deposition of nickel, in accordance with the implementation of step a), can be carried out by impregnation, dry or in excess, or by deposition-precipitation, according to methods well known to those skilled in the art.

Said step a) is preferably carried out by impregnating the support, consisting for example of bringing the support into contact with at least one aqueous or organic solution (for example methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)) or consisting of a mixture of water and at least one organic solvent, comprising, preferably consisting of, at least one nickel precursor at least partially in the dissolved state, or else in bringing the support into contact with at least one colloidal solution comprising, preferably consisting of, at least one precursor of nickel, in oxidized form (nanoparticles of oxides, oxy(hydroxide) or hydroxide of nickel) or in reduced form (metallic nanoparticles of nickel in the reduced state). Preferably, the solution is aqueous. The pH of this solution may be modified by the possible addition of an acid or a base.

Preferably, said step a) is carried out by dry impregnation, which consists in bringing the support into contact with at least one solution, containing, preferably consisting of, at least one nickel precursor, the volume of the solution of which is between 0.25 and 1.5 times the porous volume of the support of the support to be impregnated.

When the nickel precursor is introduced in aqueous solution, a nickel precursor is advantageously used in the form of nitrate, carbonate, chloride, sulphate, hydroxide, hydroxycarbonate, formate, acetate, oxalate , of complexes formed with acetylacetonates, or of tetrammine or hexammine complexes, or of any other inorganic derivative which is soluble in aqueous solution, which is brought into contact with said support. Advantageously used as nickel precursor, nickel nitrate, nickel carbonate, nickel chloride, nickel hydroxide, nickel hydroxycarbonate. Very preferably, the nickel precursor is nickel nitrate, nickel carbonate or nickel hydroxide.

The nickel precursor is supplied to step a) at a desired concentration to obtain on the final catalyst (ie obtained at the end of step g) reduction or step h) passivation if the latter is carried out) a content of between 9 and 60% by weight of nickel element relative to the total weight of the catalyst, preferably between 9 and 57% by weight, more preferably between 9.5 and 55% by weight, and even more preferably between 9, 5 and 50% by weight.

Step b) Drying of the impregnated support

Step b) of drying the impregnated support is carried out at a temperature below 250°C, preferably between 15 and 180°C, more preferably between 30 and 160°C, even more preferably between 50 and 150°C, and even more preferentially between 70 and 140° C., for a duration typically comprised between 10 minutes and 24 hours. Longer durations are not excluded, but do not necessarily bring improvement.

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 under an atmosphere containing oxygen 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 at atmospheric pressure and in the presence of air or nitrogen.

Step c) Heat treatment of the dried catalyst (optional step)

The catalyst precursor obtained at the end of step b) can undergo an additional heat treatment step at a temperature between 250 and 1000° C. and preferably between 250 and 750° C., for a duration typically between 15 minutes and 10 hours, under an inert atmosphere or under an atmosphere containing oxygen, in the presence of water or not. Longer treatment times are not excluded, but do not bring necessary improvement.

The term “heat treatment” is understood to mean the temperature treatment respectively without the presence or in the presence of water. In the latter case, contact with water vapor can take place at atmospheric pressure or at autogenous pressure. Several combined cycles without the presence or with the presence of water can be carried out.

In the event of the presence of water, the water content is preferably between 150 and 900 grams per kilogram of dry air, and even more preferably between 250 and 650 grams per kilogram of dry air.

Thus, after the drying step b), or after the optional heat treatment step c), the catalyst precursor comprises nickel in the oxide form, that is to say in the NiO form, and copper in the form oxide, i.e. in CuO form.

Step d) Bringing a nickel precursor and a copper precursor into contact with the support

The deposition of nickel and copper on the catalyst precursor obtained at the end of stage b), optionally of stage c) can be carried out by impregnation, dry or in excess, or by deposition – precipitation, according to methods well known to those skilled in the art.

Said step d) is preferably carried out by impregnation of the catalyst precursor consisting for example of bringing said support into contact with at least one aqueous or organic solution (for example methanol or ethanol or phenol or acetone or toluene or dimethyl sulfoxide (DMSO)) or consisting of a mixture of water and at least one organic solvent, comprising, preferably consisting of, at least one nickel precursor and at least one copper precursor at least partially in the dissolved state, or even by bringing said catalyst precursor into contact with at least one colloidal solution comprising, preferably consisting of, at least one nickel precursor and one copper precursor in oxidized form (nanoparticles oxide, oxy(hydroxide) or hydroxide of nickel and copper) or in reduced form (metallic nanoparticles of nickel and copper in the reduced state). Preferably, the solution is aqueous. The pH of this solution can be modified by the possible addition of an acid or a base.

Preferably, said step d) is carried out by dry impregnation, which consists in bringing the support of the catalyst precursor into contact with a solution, comprising, preferably consisting of, at least one precursor of nickel and at least one precursor of copper, the volume of the solution of which is between 0.25 and 1.5 times the porous volume of the support to be impregnated.

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

When the copper precursor is introduced in aqueous solution, a copper precursor in mineral or organic form is advantageously used. In mineral form, the copper precursor can be chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulphate, copper chloride, copper bromide, copper iodide or copper fluoride. Very preferably, the copper precursor salt is copper nitrate.

According to the invention, the nickel precursor is supplied to step d) at a desired concentration to obtain on the final catalyst (ie obtained at the end of step g) of reduction or step hi) of passivation if the latter is carried out) a content of between 0.5 and 10% by weight of nickel element relative to the total weight of the final catalyst, preferably between 0.5 and 8% by weight, more preferably between 1 and 7% by weight, even more preferably between 1 and 5% by weight.

The amounts of the copper precursor(s) introduced into the solution according to step d) are chosen such that the total copper content is between 0.5 and 15% by weight of copper element relative to the total weight of the catalyst. (ie obtained at the end of step g) of reduction or of step h) of passivation if the latter is carried out), preferably between 0.5 and 12% by weight, preferably between 0 75 and 10% by weight, and even more preferably between 1 and 9% by weight.

Step e) Drying of the impregnated support

Step e) of drying the impregnated support is carried out at a temperature below 250°C, preferably between 15 and 180°C, more preferably between 30 and 160°C, even more preferably between 50 and 150°C, and even more preferentially between 70 and 140° C., for a duration typically comprised between 10 minutes and 24 hours. Longer durations are not excluded, but do not necessarily bring improvement.

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 under an atmosphere containing oxygen 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 at atmospheric pressure and in the presence of air or nitrogen.

f) Heat treatment of the dried catalyst (optional step)

The dried catalyst precursor can undergo an additional heat treatment step, before step g) of reduction, at a temperature between 250 and 1000° C. and preferably between 250 and 750° C., for a duration typically between 15 minutes and 10 hours, under an inert atmosphere or under an atmosphere containing oxygen, in the presence of water or not. Longer treatment times are not excluded, but do not bring necessary improvement.

The term “heat treatment” is understood to mean the temperature treatment respectively without the presence or in the presence of water. In the latter case, contact with water vapor can take place at atmospheric pressure or at autogenous pressure. Several combined cycles without the presence or with the presence of water can be carried out. After this or these treatment(s), the catalyst precursor comprises nickel in oxide form, that is to say in NiO form.

In the event of the presence of water, the water content is preferably between 150 and 900 grams per kilogram of dry air, and even more preferably between 250 and 650 grams per kilogram of dry air.

Step g) Reduction with a reducing gas

Prior to the use of the catalyst in the catalytic reactor and the implementation of a hydrogenation process, a reducing treatment step g) is carried out in the presence of a reducing gas so as to obtain a catalyst comprising nickel in least partially in metallic form. This step is advantageously carried out in situ , that is to say after loading the catalyst into a reactor for the hydrogenation of aromatic or polyaromatic compounds. This treatment makes it possible to activate said catalyst and to form metallic particles, in particular nickel in the zero valent state. Performing the catalyst reduction treatment in situ makes it possible to dispense with an additional step of passivation of the catalyst by an oxygenated compound or by CO ₂ , which is necessarily the case when the catalyst is prepared by carrying out a reduction treatment. ex-situ, that is to say outside the reactor used for the hydrogenation of aromatic or polyaromatic compounds. Indeed, when the reducing treatment is carried out ex-situ, it is necessary to carry out a passivation step in order to preserve the metallic phase of the catalyst in the presence of air (during transport and loading operations of the catalyst in the reactor of hydrogenation), then to carry out a new step of reduction of the catalyst.

The reducing gas is preferably hydrogen. The hydrogen can be used pure or in a mixture (for example a hydrogen/nitrogen, hydrogen/argon, hydrogen/methane mixture). In the case where the hydrogen is used as a mixture, all the proportions are possible.

According to an essential aspect of the preparation process according to the invention, said reducing treatment is carried out at a temperature greater than or equal to 150° C. and less than 250° C., preferably between 160 and 230° C., and more preferably between 170 and 220°C. The duration of the reducing treatment is between 5 minutes and less than 5 hours, preferably between 10 minutes and 4 hours, and even more preferably between 10 minutes and 110 minutes.

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

Furthermore, the presence of copper in the catalyst makes it possible to maintain good activity of the catalyst and good life of the catalyst when the latter is brought into contact with a hydrocarbon feedstock comprising sulfur. Indeed, compared to nickel, the copper present in the catalyst more easily captures the sulfur compounds included in the charge, which limits the irreversible poisoning of the active sites. The rise in temperature up to the desired reduction temperature is generally slow, for example fixed between 0.1 and 10° C./min, preferably between 0.3 and 7° C./min.

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

Step h) Passivation (optional)

The catalyst prepared according to the process according to the invention can advantageously undergo a step of passivation by a sulfur compound which makes it possible to improve the selectivity of the catalysts and to avoid thermal runaways during the start-up of new catalysts ("run-away" according to Anglo-Saxon terminology). Passivation generally consists in irreversibly poisoning with the sulfur compound the most virulent active sites of nickel which exist on the new catalyst and therefore in attenuating the activity of the catalyst in favor of its selectivity. The passivation step is carried out by implementing methods known to those skilled in the art

The passivation step with a sulfur compound is generally carried out at a temperature of between 20 and 350° C., preferably between 40 and 200° C., for 10 to 240 minutes. The sulfur compound is for example chosen from the following compounds: thiophene, thiophane, alkylmonosulfides such as dimethylsulfide, diethylsulfide, dipropylsulfide and propylmethylsulfide or else an organic disulfide of formula HO-R ₁ -SSR ₂ -OH such as di-thio-di -ethanol of formula HO-C ₂ H ₄ -SSC ₂ H ₄ -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.

Catalyst

The catalyst obtainable by the preparation process according to the invention comprises an active phase comprising nickel and copper, part of the nickel and copper of which is in the form of a nickel-copper alloy, corresponding advantageously in the formula Ni _x Cu _y with x between 0.1 and 0.9 and including between 0.1 and 0.9, and a support in the form of a refractory oxide chosen from silica, l alumina, silica-alumina.

The copper content is between 0.5 and 15% by weight of copper element relative to the total weight of the catalyst, preferably between 0.5 and 12% by weight, preferably between 0.75 and 10% by weight , and even more preferably between 1 and 9% by weight.

The total nickel content is between 10 and 65% by weight, preferably between 14 and 50% by weight, preferably between 20 and 45% by weight of said element relative to the total weight of the catalyst.

The nickel content included in the copper-nickel alloy formed by the preparation process according to the invention is between 0.5 and 15% by weight of copper element relative to the total weight of the catalyst, preferably between 1 and 12 % by weight, and more preferably between 1 and 10% by weight.

The molar ratio between nickel and copper is between 0.5 and 5, preferably between 0.7 and 4.5, more preferably between 0.9 and 4.

The porous support is selected from the group consisting of silica, alumina and silica-alumina. Even more preferably, the support is alumina. Alumina can be present in all possible crystallographic forms: alpha, delta, theta, chi, rho, eta, kappa, gamma, etc., taken alone or in a mixture. Preferably, the support is chosen from alpha, delta, theta, gamma alumina.

The specific surface of the support is generally greater than or equal to 30 m ² /g, preferably greater than or equal to 50 m ² /g, more preferentially comprised between 60 m ² /g and 500 m ² /g, and even more preferentially comprised between 70 m ² /g and 400 m ² /g. The BET specific surface is measured by nitrogen physisorption.

The total pore volume of the support is generally between 0.1 and 1.5 cm ³ /g, preferably between 0.35 and 1.2 cm ³ /g, and even more preferably between 0.4 and 1, 0 cm ³ /g, and even more preferably between 0.45 and 0.9 cm ³ /g.

Said catalyst is generally presented in all the forms known to those skilled in the art, for example in the form of beads (generally having a diameter of between 1 and 8 mm), extrudates, tablets, hollow cylinders. Preferably, it consists of extrudates with a diameter generally between 0.5 and 10 mm, preferably between 0.8 and 3.2 mm and very preferably between 1.0 and 2.5 mm and of average length between 0.5 and 20 mm. The term "average diameter" of the extrudates means the average diameter of the circle circumscribed to the cross section of these extrudates. The catalyst can advantageously be presented in the form of cylindrical, multi-lobed, tri-lobed or quadri-lobed extrudates. Preferably, its shape will be trilobed or quadrilobed. The shape of the lobes can be adjusted according to all known methods of the prior art.

The specific surface of the support is generally greater than or equal to 30 m ² /g, preferably greater than or equal to 50 m ² /g, more preferentially comprised between 60 m ² /g and 500 m ² /g, and even more preferentially comprised between 70 m ² /g and 400 m ² /g.

The total pore volume of the catalyst is generally between 0.1 and 1.5 cm ³ /g, preferably between 0.35 and 1.2 cm ³ /g, and even more preferably between 0.4 and 1, 0 cm ³ /g, and even more preferably between 0.45 and 0.9 cm ³ /g.

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

The mesoporous volume of the catalyst is generally at least 0.10 mL/g, preferably at least 0.20 mL/g, preferably between 0.25 mL/g and 0.80 mL/g, more preferably between 0.30 and 0.65 mL/g.

The median mesoporous diameter is advantageously between 3 nm and 25 nm, and preferably between 6 and 20 nm, and particularly preferably between 8 and 18 nm.

The catalyst advantageously has a median macroporous diameter of between 50 and 1500 nm, preferably between 80 and 1000 nm, even more preferably between 250 and 800 nm.

Preferably, the catalyst has low microporosity, very preferably it has no microporosity.

Aromatics hydrogenation process

The present invention also relates to a process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a charge of hydrocarbons having a final boiling point less than or equal to 650° C., generally between 20 and 650° C. , and preferably between 20 and 450°C. Said hydrocarbon charge containing at least one aromatic or polyaromatic compound can be chosen from the following petroleum or petrochemical fractions: catalytic reforming reformate, kerosene, light gas oil, heavy gas oil, cracking distillates, such as FCC recycle oil, coker diesel, hydrocracking distillates.

The content of aromatic or polyaromatic compounds contained in the hydrocarbon charge treated in the hydrogenation process according to the invention is generally between 0.1 and 80% by weight, preferably between 1 and 50% by weight, and particularly preferably between 2 and 35% by weight, the percentage being based on the total weight of the hydrocarbon charge. The aromatic compounds present in said hydrocarbon charge are, for example, benzene or alkylaromatics such as toluene, ethylbenzene, o-xylene, m-xylene, or p-xylene, or alternatively aromatics having several aromatic (polyaromatic) rings such as naphthalene.

The sulfur or chlorine content of the charge is generally less than 5000 ppm by weight of sulfur or chlorine, preferably less than 100 ppm by weight, and in a particularly preferred manner less than 10 ppm by weight.

The technological implementation of the process for the hydrogenation of aromatic or polyaromatic compounds is for example carried out by injection, in ascending or descending current, of the hydrocarbon charge and hydrogen into at least one fixed-bed reactor. Said reactor can be of the isothermal type or of the adiabatic type. An adiabatic reactor is preferred. The hydrocarbon charge can advantageously be diluted by one or more re-injection(s) of the effluent, from said reactor where the hydrogenation reaction of the aromatics takes place, at various points of the reactor, located between the inlet and the outlet of the reactor in order to limit the temperature gradient in the reactor. The technological implementation of the process for the hydrogenation of aromatics according to the invention can also be advantageously carried out by the implantation of at least said supported catalyst in a reactive distillation column or in reactors-exchangers or in a reactor of the type slurries. The hydrogen flow can be introduced at the same time as the charge to be hydrogenated and/or at one or more different points of the reactor.

The hydrogenation of the aromatic or polyaromatic compounds can be carried out in the gas phase or in the liquid phase, preferably in the liquid phase. In general, the hydrogenation of aromatic or polyaromatic compounds is carried out at a temperature between 30 and 350° C., preferably between 50 and 325° C., at a pressure between 0.1 and 20 MPa, from preferably between 0.5 and 10 MPa, at a hydrogen/(aromatic compounds to be hydrogenated) molar ratio between 0.1 and 10 and at an hourly volumetric speed VVH of between 0.05 and 50 h ^-1 , preferably between 0, 1 and 10 h ^-1 of a hydrocarbon charge containing aromatic or polyaromatic compounds and having a final boiling point less than or equal to 650°C, generally between 20 and 650°C, and preferably between 20 and 450 °C.

The hydrogen flow is adjusted in order to have a sufficient quantity of it to theoretically hydrogenate all the aromatic compounds and to maintain an excess of hydrogen at the reactor outlet.

The conversion of the aromatic or polyaromatic compounds is generally greater than 20% by mole, preferably greater than 40% by mole, more preferably greater than 80% by mole, and in a particularly preferred manner greater than 90% by mole of the aromatic compounds or polyaromatics contained in the hydrocarbon charge. The conversion is calculated by dividing the difference between the total moles of the aromatic or polyaromatic compounds in the hydrocarbon feed and in the product by the total moles of the aromatic or polyaromatic compounds in the hydrocarbon feed.

According to a particular variant of the process according to the invention, a process is carried out for the hydrogenation of benzene from a hydrocarbon charge, such as the reformate from a catalytic reforming unit. The benzene content in said hydrocarbon charge is generally between 0.1 and 40% by weight, preferably between 0.5 and 35% by weight, and particularly preferably between 2 and 30% by weight, the percentage by weight being based on the total weight of the hydrocarbon charge.

The sulfur or chlorine content of the charge is generally less than 10 ppm by weight of sulfur or chlorine respectively, and preferably less than 2 ppm by weight.

The hydrogenation of the benzene contained in the hydrocarbon charge can be carried out in the gaseous phase or in the liquid phase, preferably in the liquid phase. When it is carried out in the liquid phase, a solvent may be present, such as cyclohexane, heptane, octane. In general, the hydrogenation of benzene is carried out at a temperature of between 30 and 250° C., preferably between 50 and 200° C., and more preferably between 80 and 180° C., at a pressure of between 0.1 and 10 MPa, preferably between 0.5 and 4 MPa, at a hydrogen/(benzene) molar ratio between 0.1 and 10 and at an hourly volumetric speed VVH of between 0.05 and 50 h ^-1 , preferably between 0.5 and 10 h ^-1 .

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

The invention will now be illustrated via the examples below which are in no way limiting.

Examples

For all the catalysts mentioned in the examples mentioned below, the support is an alumina A having a specific surface area of 80 m²/g, a pore volume of 0.7 mL/g (cm ³ /g) and a mesoporous median diameter of 12 nm.

Example 1: Preparation of an aqueous solution of Ni precursors

The aqueous solution of Ni precursors (solution S) used for the preparation of catalysts A to E is prepared by dissolving 43.5 g of nickel nitrate (NiNO ₃ , supplier Strem Chemicals®) in a volume of 13 mL of water distilled. The solution S is obtained, the Ni concentration of which is 350 g of Ni per liter of solution.

Example 2: Catalyst A - 20% by weight of Ni (comparative)

The solution S prepared in Example 1 is dry impregnated with 10 g of alumina A. The solid thus obtained is then dried in an oven overnight at 120° C., then calcined under an air flow of 1 L/ h/g of catalyst at 450° C. for 2 hours. The calcined catalyst thus prepared contains 15% by weight of the element nickel relative to the total weight of the catalyst supported on alumina.

The catalyst precursor is then reduced under the conditions as described in Example 8 below.

Example 3: Catalyst B - 20% by weight of Ni + Cu in co-impregnation with a Ni/Cu ratio=3 (comparative)

A solution of copper nitrate is prepared so as to obtain in the end a ratio Ni/Cu=3 on the final catalyst is co-impregnated dry with the solution S prepared in example 1 on 10 g of alumina A. The solid thus obtained is then dried in an oven overnight at 120°C. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor is then reduced under the conditions as described in Example 8 below.

Example 4: Catalyst C - Impregnation of 20% by weight of Ni followed by Impregnation of Ni+Cu (5% by weight Ni and molar ratio Ni/Cu=3) (according to the invention)

Solution S is impregnated dry on 10 g of alumina to obtain 20% by weight of Ni alone relative to the total weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor C1 is obtained. A solution of copper nitrate is prepared so as to obtain in the end a ratio Ni/Cu=3 on the intermediate catalyst and is dry co-impregnated with the solution S prepared in example 1 on the catalyst precursor C1. The Ni content added at this stage is 5% by weight relative to the weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor is then reduced under the conditions as described in Example 8 below.

Example 5: Catalyst D - Impregnation of 20% by weight of Ni followed by Impregnation of Ni+Cu (2% by weight Ni and molar ratio Ni/Cu=3) (according to the invention)

Solution S is impregnated dry on 10 g of alumina to obtain 20% by weight of Ni alone relative to the total weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor C1 is obtained. A solution of copper nitrate is prepared so as to obtain in the end a ratio Ni/Cu=3 on the intermediate catalyst and is dry co-impregnated with the solution S prepared in example 1 on the catalyst precursor C1. The Ni content added at this stage is 2% by weight relative to the weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor is then reduced under the conditions as described in Example 8 below.

Example 6: Catalyst E - Impregnation of 20% by weight of Ni followed by Impregnation of Ni+Cu (5% by weight Ni and molar ratio Ni/Cu=2) (according to the invention)

Solution S is impregnated dry on 10 g of alumina to obtain 20% by weight of Ni alone relative to the total weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor C1 is obtained. A solution of copper nitrate is prepared so as to obtain in the end a Ni/Cu=2 ratio on the intermediate catalyst and is dry co-impregnated with the solution S prepared in example 1 on the catalyst precursor C1. The Ni content added at this stage is 5% by weight relative to the weight of the final catalyst. The solid thus obtained is then dried in an oven overnight at 120°C, then calcined under an air flow of 1 L/h/g of catalyst at 450°C for 2 hours.

The catalyst precursor is then reduced under the conditions as described in Example 8 below.

Example 7: Characterization

All the catalysts contain the contents targeted during impregnation, i.e. 20% of nickel element (characterized by X-ray fluorescence) relative to the total weight of the catalyst, and the % of added copper (characterized by X-ray fluorescence) .

The amount of alloy obtained after the calcination then reduction step was determined by X-ray diffraction (XRD) analysis on catalyst samples in powder form.

The quantity of nickel in metallic form obtained after the reduction step was determined by analysis by X-ray diffraction (XRD) on samples of catalyst in powder form. Between the reduction stage and throughout the duration of characterization by XRD, the catalysts are never released into the open air. The diffraction diagrams are obtained by X-ray crystallographic analysis using a diffractometer using the conventional powder method with Kα1 radiation from copper (λ=1.5406 Å).

The reduction rate was calculated by calculating the area of the Ni ⁰ line located around 52°2θ, on all the diffractograms of each sample of catalyst analyzed, then by subtracting the signal present from room temperature under the line at 52° and which is due to the alumina.

Table 1 below summarizes the reduction rates or even the metallic nickel content Ni° (expressed in % weight relative to the total weight of Ni) for all the catalysts A to E characterized by XRD after a reduction step at 190 °C for 90 minutes under hydrogen flow. These values were also compared with the reduction rate obtained for catalyst A (Ni alone) after a conventional reduction step (i.e. at a temperature of 400°C for 15 hours under a flow of hydrogen) .

At room temperature on all the catalysts, after calcination, containing copper and nickel, we detect alumina in delta and theta form, and large lines of NiO and CuO.

We also detect after reduction a line corresponding to the alloy in the form of Ni _0.76 Cu _0.24.

In order to evaluate the rate of reducibility and therefore the formation of Ni ⁰ , we measure the area of the Ni ⁰ line located around 52°2θ, on all the diffractograms, by subtracting the signal present from room temperature under the line at 52° and which is due to the alumina. It is thus possible to determine the relative percentage of Ni ⁰ crystallized after the reduction.

Table 1 below summarizes the reducibility rates or the Ni° content for all the catalysts characterized by XRD after reduction at 190°C for 90 minutes under a hydrogen flow. These values were also compared with the reduction rate obtained for catalyst A (Ni alone) after a conventional reduction step (i.e. at a temperature of 400°C for 15 hours under a flow of hydrogen) . Catalyst Final reduction Ni content for the ^1st imp. (% wt) Ni content for the ^2nd imp. (% wt) Ni/Cu molar ratio for the 2nd imp. Percentage of Ni° alone (DRX) after reduction (%) A (comparative) 400°C, 3 p.m. 15 - - 80 A (comparative) 190°C, 90 mins 15 - - 0* B (comparative) 190°C, 90 mins - 15 3 0** C (invention) 190°C, 90 mins 15 5 3 100 D (invention) 190°C, 90 mins 15 2 3 90 E (invention) 190°C, 90 mins 15 5 2 80

*Nickel as NiO

**Nickel as an alloy

For catalyst A (15% Ni alone/alumina), the nickel reducibility rate is 0% after exactly the same reduction treatment under hydrogen as for catalysts B to E.

The post-impregnation of nickel (5% by weight of Ni) and copper with a Ni/Cu ratio of 2 makes it possible to obtain Ni° reduced by around 80% in the end on the catalyst. The post-impregnation of less NiCu alloy with a content of nickel composing the alloy of 2% by weight and of copper with a Ni/Cu ratio of 3 makes it possible to obtain Ni° reduced by around 90% ultimately on the catalyst. The post-impregnation of nickel (5% by weight of Ni) and copper with a Ni/Cu ratio of 3 makes it possible to obtain 100% reduced Ni° from 190°C in the end on the catalyst.

Example 8: Catalytic tests: performance in hydrogenation of toluene

The catalysts A to E described in the examples above are also tested with respect to the hydrogenation reaction of toluene.

The hydrogenation reaction is carried out in a 500 mL stainless steel autoclave, equipped with mechanical stirring with magnetic drive and able to operate under a maximum pressure of 100 bar (10 MPa) and temperatures between 5°C and 200 °C.

In an autoclave are added 216 mL of n-heptane (VWR® supplier, purity > 99% chromanorm HPLC) and 2 mL of catalyst (for catalysts from A to G). Then the autoclave is pressurized under 35 bar (3.5 MPa) of hydrogen. The catalyst is first reduced in situ , at 190°C for 90 minutes (temperature rise ramp of 1°C/min) for catalysts A to E (which corresponds to step h) of the preparation process of the catalyst according to the invention according to one embodiment).

Then the autoclave is brought to the test temperature equal to 80°C. At time t=0, approximately 26 g of toluene (SDS® supplier, purity > 99.8%) are introduced into the autoclave (the initial composition of the reaction mixture is then toluene 6% by weight / n-heptane 94% by weight) and stirring is started at 1600 rpm. The pressure is kept constant at 35 bar (3.5 MPa) in the autoclave using a reservoir bottle located upstream of the reactor.

Another test was carried out for catalyst A, but with a catalyst reduction temperature of 400° C. for 15 hours.

The progress of the reaction is monitored by taking samples of the reaction medium at regular time intervals: the toluene is completely hydrogenated to methylcyclohexane. Hydrogen consumption is also monitored over time by the decrease in pressure in a reservoir bottle located upstream of the reactor.

The catalytic activities measured for catalysts A to E are reported in Table 2 below. They are related to the catalytic activity (A_HYD) measured for catalyst A prepared under conventional reduction conditions (at a temperature of 400°C for 15 hours under a flow of hydrogen). Catalyst Final reduction Ni content for the ^1st imp. (% wt) Ni content for the ^2nd imp. (% wt) Ni/Cu molar ratio for the 2nd imp. Percentage of Ni° (DRX) after reduction (%) A _HYD1 (%) A (comparative) 400°C, 3 p.m. 15 - - 80 100 A (comparative) 190°C, 90 mins 15 - - 0 0 B (comparative) 190°C, 90 mins - 15 3 0 10 C (invention) 190°C, 90 mins 15 5 3 100 180 D (invention) 190°C, 90 mins 15 2 3 90 130 E (invention) 190°C, 90 mins 15 5 2 70 80

This clearly shows the improved performance of catalysts C, D and E according to the invention, compared to the Ni catalyst alone on alumina reduced at 190° C. for 90 min, which is completely inactive. Furthermore, it should be noted that the NiCu alloy alone (catalyst B) has an activity that is much lower than the reference (around 10%).

Claims (14)

Process for the preparation of a catalyst for the hydrogenation of aromatic or polyaromatic compounds comprising nickel, in an amount of 10 and 65% by weight by nickel element relative to the total weight of the catalyst, copper, in an amount of 0.5 to 15 % by weight of copper element relative to the total weight of the catalyst, and a support comprising at least one refractory oxide chosen from silica, alumina and silica-alumina, which process comprises the following steps:
a) a step of bringing said support into contact with a solution comprising at least one nickel precursor is carried out;
b) at least one stage of drying the catalyst precursor is carried out at the end of stage a) at a temperature below 250° C.;
c) optionally, heat treatment of the catalyst precursor obtained at the end of step b) is carried out at a temperature of between 250 and 1000° C., in the presence or absence of water;
d) a step is carried out for bringing the catalyst precursor obtained at the end of step b), optionally at the end of step c), into contact with at least one solution containing at least one copper precursor and a nickel precursor at a nickel concentration desired to obtain on the final catalyst a content of between 0.5 and 15% by weight of nickel element relative to the total weight of the final catalyst;
e) at least one step of drying the catalyst precursor is carried out at the end of step d) at a temperature below 250° C.;
f) optionally, heat treatment of the catalyst precursor obtained at the end of step e) is carried out at a temperature of between 250 and 1000° C., in the presence or absence of water;
g) reducing the catalyst precursor from step e), optionally step f), by bringing said catalyst precursor into contact with a reducing gas at a temperature between 150 and 250°C. Process according to claim 1, in which in step d) the molar ratio between nickel and copper is between 0.5 and 5. Process according to one of Claims 1 or 2, in which step g) is carried out at a temperature of between 160 and 230°C. Process according to any one of Claims 1 to 3, in which step g) is carried out at a temperature of between 170 and 220°C. Process according to any one of Claims 1 to 4, in which step g) is carried out between 10 minutes and 110 minutes. Process according to any one of Claims 1 to 5, further comprising a stage of passivation of the catalyst precursor by a sulfur compound after stage g) of reduction. Process according to Claim 6, in which the passivation step is carried out at a temperature of between 20 and 350°C for 10 to 240 minutes. Process according to one of Claims 6 or 7, in which the said sulfur compound is chosen from thiophene, thiophane, dimethylsulphide, diethylsulphide, dipropylsulphide, propylmethylsulphide, di-thio-di-ethanol. Process according to any one of Claims 1 to 8, in which the copper precursor supplied during step d) is chosen from copper acetate, copper acetylacetonate, copper nitrate, copper sulphate , copper chloride, copper bromide, copper iodide or copper fluoride. A method according to claim 9, wherein the copper precursor is copper nitrate. Process according to any one of Claims 1 to 10, in which the reducing gas in step g) is dihydrogen. Process according to Claim 11, in which the hydrogen flow rate, expressed in L/hour/gram of catalyst precursor, is between 0.01 and 100 L/hour/gram of catalyst precursor. Process according to any one of Claims 1 to 12, in which the nickel precursor supplied during stage a) and/or d) is chosen from nickel nitrate, nickel carbonate or nickel hydroxide. Process for the hydrogenation of at least one aromatic or polyaromatic compound contained in a charge of hydrocarbons having a final boiling point less than or equal to 650°C, said process being carried out in the gaseous phase or in the liquid phase, at a temperature between 30 and 350°C, at a pressure between 0.1 and 20 MPa, at a hydrogen/(aromatic compounds to be hydrogenated) molar ratio between 0.1 and 10 and at an hourly volumetric speed VVH between 0.05 and 50 h ^-1 , in the presence of a catalyst obtained according to any one of Claims 1 to 13.