Selective hydrogenation catalyst with specific distribution of nickel and molybdenum

Abstract

A selective hydrogenation catalyst, which comprises an active phase containing a Group VIB metal and a Group VIII metal and a porous support containing alumina, the content of the Group VIB metal measured in oxide form being 1-18% by weight relative to the total weight of the catalyst, the content of the Group VIII metal in the active phase measured in oxide form being 1-20% by weight relative to the total weight of the catalyst, characterized in that the molar ratio between the Group VIII metal in the active phase and the Group VIB metal in the active phase is 1.0-3.0 mol / mol, the Group VIII metal is uniformly distributed in the porous support with a distribution coefficient R of 0.8-1.2 measured using a Castaing microprobe, and the Group VIB metal is distributed at the outer periphery of the porous support with a distribution coefficient R of less than 0.8.

Description

Background Art

[0002] Producing gasoline that meets new environmental standards requires a significant reduction in its sulfur content to a value that generally does not exceed 50 ppm, preferably less than 10 ppm.

[0003] In addition, it is known that reformed gasoline, and more particularly reformed gasoline produced from catalytic cracking (which can account for 30% - 50% of the gasoline pool), has a high content of monoolefins and sulfur.

[0004] For this reason, nearly 90% of the sulfur present in gasoline is attributed to gasoline produced by the catalytic cracking process, which is hereinafter referred to as FCC (fluid catalytic cracking) gasoline. Thus, FCC gasoline constitutes a preferred feedstock for the process of the present invention. More generally, the process according to the present invention is applicable to any gasoline fraction containing a certain proportion of diolefins, and the gasoline fraction may also contain some lighter compounds belonging to the C3 and C4 fractions.

[0005] Gasoline from the cracking unit is usually rich in olefins and sulfur, but also rich in diolefins, and for gasoline from catalytic cracking, the content of diolefins can be as high as 5% by weight. Diolefins are unstable compounds that can easily polymerize, and they usually must be removed before any treatment of these gasolines (such as hydrodesulfurization treatment aimed at meeting the sulfur content specification in gasoline). However, this hydrogenation must be selective for diolefins and must limit the hydrogenation of olefins to limit hydrogen consumption and the loss of octane number in gasoline. In addition, as described in patent application EP01077247 A1, it is advantageous to convert mercaptans by increasing the molecular weight before the desulfurization step, because this can produce a desulfurized gasoline fraction mainly composed of olefins having 5 carbon atoms by simple distillation without loss of octane number. After selective hydrogenation and increasing the molecular weight of light sulfur-containing compounds, the amount of sulfur present in the feedstock does not change; only the nature of the sulfur changes due to the increase in the molecular weight of mercaptans.

[0006] In addition, the diolefin compounds present in the feedstock to be treated are unstable and tend to form gums by polymerization. This gum formation causes the gradual deactivation of the downstream hydrodesulfurization catalyst or the gradual blockage of the reactor. Therefore, for industrial applications, it is important to use a catalyst that limits polymer formation, that is, a catalyst with low acidity or whose porosity is optimized to promote the continuous extraction of polymers or gum precursors by the hydrocarbons in the feedstock to ensure the maximum cycle time of the catalyst.

[0007] The content of the active phase and the particle size of the active phase are two of the criteria that affect the activity and selectivity of the catalyst. It is also known that the macroscopic distribution of metal particles in the support constitutes an important criterion. For example, document CN104275191 discloses a selective hydrogenation catalyst for FCC gasoline, which includes nickel and molybdenum deposited on an alumina support, and the nickel and molybdenum are distributed in the form of a shell at the outer periphery of the support.

[0008] The present invention proposes a novel hydrotreating catalyst that can selectively hydrogenate polyunsaturated compounds, more particularly dienes, and can also increase the molecular weight of light sulfur-containing compounds, more particularly mercaptans.

[0009] Subject matter of the invention

[0010] The present invention relates to a selective hydrogenation catalyst, which includes an active phase containing at least one Group VIB metal and at least one Group VIII metal and a porous support containing at least alumina. The content of the Group VIB metal measured in oxide form is 1-18% by weight relative to the total weight of the catalyst, and the content of the Group VIII metal in the active phase measured in oxide form is 1-20% by weight relative to the total weight of the catalyst. It is characterized in that the molar ratio between the Group VIII metal in the active phase and the Group VIB metal in the active phase is 1.0-3.0 mol / mol, the Group VIII metal is uniformly distributed in the porous support with a distribution coefficient R of 0.8-1.2 measured by a Castaing microprobe, and the Group VIB metal is distributed at the outer periphery of the porous support with a distribution coefficient R of less than 0.8.

[0011] The applicant has surprisingly found that a catalyst based on at least one Group VIII metal and at least one Group VIB metal distributed in a specific manner in the catalyst support has better activity and better selectivity for diene hydrogenation, which allows the feedstock to better approach the active phase while achieving the conversion of light sulfur-containing compounds, and this conversion is at least as good as, or even better than, the catalysts disclosed in the prior art. Without wishing to be bound by any theory, it is contemplated that diene hydrogenation is limited by the diffusion of reactants in the support; thus, the active phase containing at least one Group VIB metal mainly present at the outer periphery of the support can improve the activity and selectivity of selective hydrogenation. In addition, the active phase based on the Group VIII metal for achieving the conversion of light sulfur-containing compounds does not seem to be limited by the diffusion of reactants in the support. Therefore, the active phase of the Group VIII metal present in a uniform manner throughout the volume of the support can maintain good performance in converting light sulfur-containing compounds.

[0012] Preferably, at least 80% by weight of the Group VIB metal is distributed in the shell layer at the outer periphery of the carrier, and the thickness of the shell layer is 200 - 1000 µm.

[0013] In one embodiment according to the present invention, the carrier further comprises at least one spinel MAl₂O₄, wherein M is selected from nickel and cobalt.

[0014] Preferably, the molar ratio between the metal M of the porous carrier and the Group VIB metal of the active phase is 0.5 - 1.5 mol / mol.

[0015] Preferably, the molar ratio between the metal M of the porous carrier and the Group VIII metal of the active phase is 0.3 - 1.5 mol / mol.

[0016] Preferably, the molar ratio between the sum of the contents of the metal M and the Group VIII metal of the active phase and the content of the Group VIB metal is 2.2 - 3.2 mol / mol.

[0017] Preferably, the molar ratio between the Group VIII metal of the active phase and the Group VIB metal of the active phase is 1.5 - 3.0 mol / mol.

[0018] Preferably, the content of the metal M measured in the form of an oxide is 0.5 - 10% by weight relative to the total weight of the catalyst.

[0019] Preferably, the specific surface area of the catalyst is 110 - 190 m² / g.

[0020] Preferably, the Group VIII metal is nickel and the Group VIB metal is molybdenum.

[0021] Another subject according to the present invention relates to a method for preparing the catalyst according to the present invention, which comprises the following steps:

[0022] a) contacting the carrier with an aqueous or organic solution containing a salt of at least one metal M selected from nickel and cobalt;

[0023] b) aging the impregnated carrier at the end of step a) for a period of 0.5 hour - 24 hours at a temperature below 50 °C;

[0024] c) drying the aged and impregnated carrier obtained at the end of step b) at a temperature of 50 °C - 200 °C, advantageously for a period of 1 - 48 hours;

[0025] d) calcining the solid obtained in step c) at a temperature of 500 °C - 1000 °C to obtain a spinel of the MAl₂O₄ type;

[0026] e) performing the following sub - steps:

[0027] i) Contact the solid obtained at the end of step d) with a solution comprising at least one metal active phase precursor based on a Group VIII metal, and then age the catalyst precursor for a period of 0.5 h to 12 h at a temperature below 50 °C;

[0028] ii) Contact the solid obtained at the end of step d) with a solution comprising at least one metal active phase precursor based on a Group VIB metal, and then age the catalyst precursor for a period of 0.5 h to 12 h at a temperature below 50 °C;

[0029] Step i) and step ii) are carried out separately or simultaneously in any order;

[0030] f) Dry the catalyst precursor obtained in step e) at a temperature of 50 °C - 200 °C, preferably 70 °C - 180 °C, for a period typically of 0.5 - 12 h, even more preferably 0.5 - 5 h.

[0031] In one embodiment, the method further comprises step g), in which the catalyst precursor obtained in step f) is calcined at a temperature of 200 °C - 550 °C for a period advantageously of 0.5 - 24 h.

[0032] Another subject according to the invention relates to a method for the selective hydrogenation of gasoline containing polyunsaturated compounds and light sulfur compounds, in which the gasoline and hydrogen are contacted with a catalyst according to the invention, or a catalyst obtained according to the preparation method according to the invention (in the form of a sulfide), at a temperature of 80 °C - 220 °C, at a liquid hourly space velocity of 1 h -1 to 10 h -1 and at a pressure of 0.5 - 5 MPa, with a molar ratio of hydrogen to diolefins to be hydrogenated greater than 1 and less than 10 mol / mol.

[0033] Preferably, the gasoline is fluid catalytic cracking (FCC) gasoline and has a boiling point of 0 °C - 280 °C.

[0034] Another subject according to the invention relates to a method for desulfurizing gasoline containing sulfur compounds, which comprises the following steps:

[0035] a) Carry out the selective hydrogenation step of the method for the selective hydrogenation of gasoline containing polyunsaturated compounds and light sulfur compounds according to the invention;

[0036] b) Separate the gasoline obtained in step a) into at least two fractions, said fractions comprising at least one light gasoline and at least one heavy gasoline respectively;

[0037] c) A step of hydrodesulfurizing the heavy gasoline separated in step b) on a catalyst, which can decompose at least part of the sulfur-containing compounds into H2S. Detailed Description of the Invention

[0039] Definition

[0040] In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIII according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification.

[0041] The term "specific surface area" is understood to mean the BET specific surface area (S BET , unit: m 2 / g) measured by nitrogen adsorption according to the standard ASTM D 3663 - 78 established by the Brunauer - Emmett - Teller method described in the journal "The Journal of the American Chemical Society", 1938, 60, 309.

[0042] The total pore volume of the catalyst or the support used for preparing the catalyst is understood to mean the volume measured by mercury porosimetry according to the standard ASTM D4284 - 83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dynes / cm and a contact angle of 140°. According to the recommendation on pages 1050 - 1055 of the publication "Techniques de l'ingénieur, traité analyse et caractérisation" [Techniques of the Engineer, Analysis and Characterization Treatise] written by Jean Charpin and Bernard Rasneur, the wetting angle is taken to be 140°. For better accuracy, the value of the total pore volume corresponds to the value of the total pore volume measured by mercury porosimetry on the sample minus the value of the total pore volume measured by mercury porosimetry on the same sample for a pressure corresponding to 30 psi (about 0.2 MPa).

[0043] The content of metals from Group VIII and Group VIB is measured by X - ray fluorescence spectrometry.

[0044] Definition of the distribution coefficient R

[0045] Distribution curves of elements within the catalyst pellets are obtained using a Castaing microprobe. At least 30 analysis points are carried out along the diameter of the bead or extrudate at a ratio of about 10 points on the shell of the active elements (Group VIB and Group VIII metals in the case of the present application) and about 10 points at the center of the pellet. Thereby, the distribution curve for x ϵ [-r ;+r] is obtained c(x) , where c is the local weight concentration of the element, r is the radius of the bead or extrudate, and x is the position of the analysis point along the diameter of the pellet relative to the center of the pellet.

[0046] The distribution of the element is characterized by a dimensionless distribution coefficient R, which weights the local concentration by a weight that increases as a function of the position on the diameter. By definition:

[0047]

[0048] Therefore, an element with a uniform concentration has a distribution coefficient R equal to 1, an element deposited as a dome (higher concentration at the core of the support than at the edge of the support) has a coefficient greater than 1, and an element distributed as a shell (higher concentration at the edge of the support than at the core of the support) has a coefficient less than 1. The analysis using a Castaing microprobe provides concentration values at a limited number of x values, so the numerical evaluation of R is carried out by an integration method well-known to those skilled in the art. Preferably, R is determined by the trapezoidal method.

[0049] Definition of the thickness of the metal shell of Group VIB

[0050] To analyze the distribution of the active phase of the Group VIB metal on the support, the shell thickness is measured using a Castaing microprobe (or electron microprobe microanalysis). The instrument used is a CAMECA XS100, which is equipped with four crystal monochromators to simultaneously analyze four elements. The Castaing microprobe analysis technique involves detecting the X-rays emitted by the solid after exciting the elements of the solid by a high-energy electron beam. For the purpose of this characterization, the catalyst pellets are embedded in epoxy resin blocks. These blocks are polished until a cross-section through the diameter of the bead or extrudate is reached, and then metallized by depositing carbon in a metal evaporator. The electron probe scans along the diameters of five beads or extrudates to obtain the average distribution curve of the constituent elements of the solid.

[0051] When the Group VIB metal is distributed as a shell, the local concentration of the Group VIB metal generally gradually decreases when measured from the edge of the catalyst pellet towards the inside. To measure the shell thickness that is significant for most of the particles of the Group VIB metal, the shell thickness is defined as the distance to the edge of the pellet when it contains 80 wt% of the Group VIB metal.

[0052] It is defined in the publication “Measurement of palladium crust thickness on catalyst by EPMA” by L. Sorbier et al., Materials Science and Engineering 32 (2012). To measure the crust thickness that is significant for most of the particles of Group VIB metals, the crust thickness can alternatively be defined as the distance to the edge of the pellet when it contains 80 wt% of the Group VIB metal. From the distribution curve (c(x)) obtained using a Castaing microprobe, the cumulative amount Q(y) of the Group VIB metal in the pellet as a function of the distance y to the edge of the pellet of radius r can be calculated.

[0053] For beads:

[0054]

[0055] For extrudates:

[0056]

[0057] where

[0058] r: the radius of the pellet;

[0059] y: the distance to the edge of the pellet;

[0060] x: the integration variable (position on the curve).

[0061] It is assumed that the concentration curve follows the diameter from x = -r to x = +r (x = 0 is the center).

[0062] Thus, Q(r) corresponds to the total amount of the element in the pellet. Then, y is numerically solved for the following equation:

[0063]

[0064] c is a strictly positive function, so Q is a strictly increasing function and the equation has a single solution, which is the crust thickness.

[0065] Catalyst

[0066] The catalyst according to the present invention comprises an active phase containing at least one Group VIB metal and at least one Group VIII metal and a porous support containing at least alumina, preferably consisting of, the Group VIB metal content measured in oxide form being 1-18% by weight relative to the total weight of the catalyst, the Group VIII metal content of the active phase measured in oxide form being 1-20% by weight relative to the total weight of the catalyst, wherein the Group VIII metal is uniformly distributed in the porous support with a distribution coefficient R of 0.8-1.2, preferably 0.85-1.1, more preferably 0.9-1.1 measured using a Castaing microprobe, and wherein the Group VIB metal is distributed at the outer periphery of the porous support with a distribution coefficient R of less than 0.80, preferably less than 0.70.

[0067] Advantageously, at least 80% by weight of the Group VIB metal is distributed in a shell layer at the outer periphery of the support, the thickness of the shell layer being 200-1000 µm, preferably 500-800 µm.

[0068] The content of the Group VIII metal in the active phase measured in oxide form is 1-20% by weight, preferably 2-15% by weight, even more preferably 4-13% by weight relative to the total weight of the catalyst. The Group VIII metal is preferably selected from nickel, cobalt and iron. More preferably, the Group VIII metal is nickel.

[0069] The content of the Group VIB metal in the active phase measured in oxide form is 1-18% by weight, preferably 1-15% by weight, even more preferably 2-13% by weight relative to the total weight of the catalyst. The Group VIB metal is preferably selected from molybdenum and tungsten. More preferably, the Group VIB metal is molybdenum.

[0070] Preferably, the molar ratio between the Group VIII metal of the active phase and the Group VIB element of the active phase is 1.0-3.0 mol / mol, preferably 1.5-3.0 mol / mol, more preferably 1.5-2.5 mol / mol.

[0071] Preferably, a catalyst having a total pore volume of 0.3-1.1 cm 3 / g, very preferably 0.35-0.7 cm 3 / g measured by mercury porosimetry is used. Mercury porosimetry is measured with a wetting angle of 140° using an Autopore III device from the Micromeritics® brand according to standard ASTM D4284-92.

[0072] The specific surface area of the catalyst is preferably less than 350 m 2 / g, more preferably 80 m 2 / g - 280 m² / g 2 / g, preferably from 100 m² / g to 250 m² / g, even more preferably from 110 m² / g to 190 m² / g.

[0073] In addition, the pore volume of the catalyst (with a diameter greater than 0.05 μm) measured by mercury porosimetry is preferably 5% - 50% of the total pore volume, more preferably 10% - 40% of the total pore volume.

[0074] The pore volume of the catalyst with a diameter greater than 0.1 μm is preferably 5% - 35% of the total pore volume, more preferably 10% - 30% of the total pore volume. The inventors have noticed that such a pore distribution makes it possible to limit the formation of gums in the catalyst.

[0075] Support

[0076] The porous support that can be used in the context of the present invention comprises alumina, preferably selected from the following aluminas: γ - alumina, δ - alumina, θ - alumina, η - alumina, ρ - alumina, χ - alumina, κ - alumina, alone or as a mixture. Preferably, the porous support is based on η - alumina, θ - alumina, δ - alumina, χ - alumina, alone or as a mixture. When the porous support further comprises an aluminate MAl₂O₄ (where M is selected from nickel and cobalt), the method for preparing said support is advantageously carried out by dry impregnation of an alumina comprising γ - alumina.

[0077] Advantageously, the porous support of the catalyst further comprises at least one spinel MAl₂O₄, where M is selected from nickel and cobalt. The metal M measured in oxide form is advantageously from 0.5 - 10% by weight relative to the total weight of the catalyst, preferably from 0.7 - 8% by weight, even more preferably from 1 - 5% by weight.

[0078] When the Group VIII metal of the active phase used is nickel or cobalt, the calculated molar ratio does not take into account the nickel or cobalt involved in the preparation of the support.

[0079] The presence of spinel in the catalyst according to the present invention can be measured by temperature - programmed reduction (or TPR), for example as described in Oil & Gas Science and Technology, Rev. IFP, Vol. 64 (2009), No. 1, pp. 11 - 12. According to this technique, the catalyst is heated in a stream of a reducing agent, for example in a stream of hydrogen. Measuring the hydrogen consumption as a function of temperature gives quantitative information about the reducibility of the substances present. Thus, the presence of spinel in the catalyst is represented by the hydrogen consumption at a temperature above about 800 °C.

[0080] Preferably, when the catalyst support according to the present invention contains spinel MAl2O4, the molar ratio between the sum of the contents of metal M and Group VIII metal and the content of Group VIB metal is 2.0 - 3.5 mol / mol, preferably 2.0 - 3.2 mol / mol, more preferably 2.5 - 3.2 mol / mol.

[0081] Preferably, when the catalyst support according to the present invention contains spinel MAl2O4, the molar ratio between the metal M of the porous support and the Group VIB metal of the active phase is 0.5 - 1.5 mol / mol, preferably 0.7 - 1.5 mol / L / mol, even more preferably 0.8 - 1.5 mol / mol.

[0082] Preferably, when the catalyst support according to the present invention contains spinel MAl2O4, the molar ratio between the metal M of the porous support and the Group VIII metal of the active phase is 0.3 - 1.5 mol / mol, more preferably 0.3 - 1.0 mol / mol.

[0083] Preferably, a support having a total pore volume measured by mercury porosimetry of 0.3 - 1.1 cm 3 / g, preferably 0.35 - 0.8 cm 3 / g is used.

[0084] In addition, the pore volume (with a diameter greater than 0.05 μm) of the support measured by mercury porosimetry is preferably 5% - 50% of the total pore volume, more preferably 10% - 40% of the total pore volume.

[0085] The pore volume of the support with a diameter greater than 0.1 μm is preferably 5% - 35% of the total pore volume, more preferably 5% - 30% of the total pore volume.

[0086] The specific surface area of the support is preferably less than 350 m 2 / g, more preferably 80 m 2 / g - 350 m 2 / g, preferably 100 m² / g - 330 m² / g, even more preferably 120 m² / g - 320 m² / g.

[0087] Synthesis of the support containing aluminates (optional)

[0088] The porous support that can be used in the context of the present invention contains alumina, preferably selected from the following aluminas: γ - alumina, δ - alumina, θ - alumina, η - alumina, ρ - alumina, χ - alumina, κ - alumina, alone or as a mixture. Preferably, the porous support is based on η - alumina, θ - alumina, δ - alumina, χ - alumina, alone or as a mixture.

[0089] When the porous support further comprises an aluminate MAl2O4, where M is selected from nickel and cobalt, the method for preparing the support is advantageously carried out by dry impregnation of alumina as described above (preferably comprising γ-alumina) with an aqueous solution containing an appropriate amount of metal nitrate, such as nickel nitrate or cobalt nitrate. The amount of metal nitrate corresponds to a metal content of 0.5 - 10 wt%, preferably 0.7 - 8 wt%, and even more preferably 1 - 5 wt% relative to the total weight of the catalyst (calculated as the oxide equivalent MO, where M is selected from nickel and cobalt).

[0090] After impregnation, the solid is cured at a temperature below 50°C, preferably at ambient temperature, for 0.5 - 24 hours, preferably 0.5 - 12 hours, and then dried for a period of advantageously 1 - 48 hours, preferably 2 - 12 hours, at a temperature of advantageously 50°C - 200°C, preferably 70 - 180°C. Finally, the solid is calcined for a period of advantageously 1 - 12 hours, preferably 2 - 8 hours, at a temperature of 500 - 1100°C, preferably 600 - 900°C, in a dry air stream or a moist air stream, preferably in a moist air stream. This calcination enables the formation of an aluminate MAl2O4, where M is selected from nickel and cobalt. The resulting solid is subsequently denoted by the term AlNi or AlCo.

[0091] Preparation of the catalyst

[0092] The catalyst according to the invention can be prepared by any technique known to those skilled in the art, in particular by impregnating Group VIII and Group VIB elements on the selected support. For example, the impregnation can be carried out according to the method known to those skilled in the art as dry impregnation, where only the amount of the desired element in soluble salt form is introduced into the selected solvent (such as demineralized water) in order to fill the pores of the support as precisely as possible.

[0093] The precursors of the active phase based on Group VIII metals and the precursors of the active phase based on Group VIB metals can be introduced simultaneously or successively. The impregnation of each precursor can advantageously be carried out at least twice. Thus, the different precursors can be successively impregnated with different numbers of impregnation and curing steps. One precursor can also be impregnated several times.

[0094] The carrier thus filled with the solution is aged for a period of 0.5 hours to 12 hours, preferably 0.5 hours to 6 hours, even more preferably 0.5 to 3 hours at a temperature below 50 °C, preferably at ambient temperature. In fact, without wishing to be bound by any theory, since the diffusion of the precursor of the active phase containing a Group VIB metal is slower than that of the precursor of the active phase containing a Group VIII metal, the limitation of the aging duration prevents the uniform distribution of the Group VIB metal. Subsequently, it is found that the Group VIB metal is mainly distributed at the outer periphery of the carrier, which is different from the Group VIII metal uniformly distributed in the carrier.

[0095] After the aging step, the obtained catalyst precursor is subjected to an activation treatment.

[0096] The purpose of this treatment is generally to convert the molecular precursor of the element into an oxide phase. In this case, it is an oxidation treatment, but simple drying of the catalyst can also be carried out.

[0097] In the case of drying, the catalyst precursor is dried at a temperature of 50 °C - 200 °C, preferably 70 °C - 180 °C for a period generally of 0.5 - 12 hours, even more preferably 0.5 - 5 hours.

[0098] In the case of the oxidation treatment (also called calcination), the treatment is generally carried out in air or dilute oxygen, and the treatment temperature is generally 200 °C - 550 °C, preferably 300 °C - 500 °C, advantageously generally 0.5 - 24 hours, preferably 0.5 - 12 hours, even more preferably 0.5 - 10 hours. The salts of Group VIB and Group VIII metals that can be used in the method for preparing the catalyst are, for example, cobalt nitrate, nickel nitrate, ammonium heptamolybdate or ammonium metatungstate. Any other salts known to those skilled in the art with sufficient solubility and that can decompose during the activation treatment can also be used. Advantageously, both the drying and the oxidation treatment are carried out during the process of the method for preparing the catalyst.

[0099] Preferably, the catalyst according to the present invention is prepared according to the following steps:

[0100] a) contacting a carrier with an aqueous or organic solution containing a salt of at least one metal M selected from nickel and cobalt;

[0101] b) aging the impregnated carrier at the end of step a) for a period of 0.5 hours to 24 hours, preferably 0.5 hours to 12 hours at a temperature below 50 °C, preferably at ambient temperature;

[0102] c) drying the aged and impregnated carrier obtained at the end of step b) at a temperature of 50 °C - 200 °C, preferably 70 °C - 180 °C for a period advantageously of 1 - 48 hours, preferably 2 - 12 hours;

[0103] d) Calcining the solid obtained in step c) at a temperature of 500 °C - 1000 °C, preferably 600 °C - 900 °C, advantageously for a period of 1 - 12 hours, preferably 2 - 12 hours, to obtain a spinel of the MAl2O4 type;

[0104] e) Perform the following sub - steps:

[0105] i) Contact the solid obtained at the end of step d) with a solution comprising at least one metal active phase precursor based on a Group VIII metal, and then age the catalyst precursor at a temperature below 50 °C, preferably at ambient temperature, for a period of 0.5 - 12 hours, preferably 0.5 - 6 hours, and even more preferably 0.5 - 3 hours;

[0106] ii) Contact the solid obtained at the end of step d) with a solution comprising at least one metal active phase precursor based on a Group VIB metal, and then age the catalyst precursor at a temperature below 50 °C, preferably at ambient temperature, for a period of 0.5 - 12 hours, preferably 0.5 - 6 hours, and even more preferably 0.5 - 3 hours;

[0107] Step i) and step ii) are carried out separately or simultaneously in any order;

[0108] f) Dry the catalyst precursor obtained in step e) at a temperature of 50 °C - 200 °C, preferably 70 °C - 180 °C, usually for a period of 0.5 - 12 hours, and even more preferably 0.5 - 5 hours;

[0109] g) Optionally, calcine the catalyst precursor obtained in step f) at a temperature of 200 °C - 550 °C, preferably 300 °C - 500 °C, advantageously for a period of 0.5 - 24 hours, preferably 0.5 - 12 hours, and even more preferably 0.5 - 10 hours.

[0110] Sulfidation of the catalyst

[0111] Before contacting the feedstock to be treated, the catalyst is subjected to a sulfiding step. The sulfiding is carried out in a sulfur-containing reducing medium, i.e., in the presence of H2S and hydrogen, in order to convert the metal oxides into sulfides, such as MoS2 and NiS. The sulfiding is carried out by injecting a stream containing H2S and hydrogen, or a sulfur-containing compound capable of decomposing in the presence of the catalyst and hydrogen to produce H2S, onto the catalyst. Polysulfides, such as dimethyldisulfide, are commonly used H2S precursors for sulfiding the catalyst. The temperature is adjusted so that H2S reacts with the metal oxides to form metal sulfides. The sulfiding can be carried out in situ or ex situ (inside or outside the reactor) of a hydrodesulfurization reactor at a temperature of 200 - 600 °C, more preferably 250 - 500 °C. In order to maintain activity, the metal must be substantially sulfided. An element is considered to be substantially sulfided when the molar ratio of sulfur (S) to the metal present on the catalyst is at least equal to 50% of the theoretical molar ratio corresponding to complete sulfidation of the element considered. The overall degree of sulfidation is defined by the following equation:

[0112] (S / element) 催化剂 ≥ 0.5 × (S / element) 理论

[0113] Where:

[0114] (S / element) 催化剂 is the molar ratio between sulfur (S) and the element present on the catalyst (excluding the metals (Ni or Co) used during the preparation of the support)

[0115] (S / element) 理论 is the molar ratio between sulfur and the element corresponding to complete sulfidation of the element to form a sulfide.

[0116] This theoretical molar ratio varies according to the element considered:

[0117] -(S / Fe) 理论 =1

[0118] -(S / Co) 理论 =8 / 9

[0119] -(S / Ni) 理论 =1 / 1

[0120] -(S / Mo) 理论 =2 / 1

[0121] -(S / W) 理论 =2 / 1.

[0122] Since the catalyst contains several metals, the molar ratio of S present on the catalyst to the elemental combination must also be at least equal to 50% of the theoretical molar ratio corresponding to the complete sulfidation of each element to form a sulfide, and this calculation is carried out proportionally to the relative molar fraction of each element, excluding the metals (Ni or Co) involved in the preparation of the support.

[0123] For example, for a catalyst containing molybdenum and nickel (with respective molar fractions of 0.7 and 0.3), the minimum molar ratio (S / Mo+Ni) is given by the following relationship:

[0124] (S / Mo+Ni) 催化剂 = 0.5 × [(0.7×2) + (0.3×1)].

[0125] Very preferably, the degree of sulfidation of the metal will be greater than 70%.

[0126] Sulfidation is carried out on the metal in oxide form without a prior metal reduction step. In fact, it is known that the sulfidation of reduced metals is more difficult than that of metals in oxide form.

[0127] Selective hydrogenation method

[0128] The present invention also relates to a method for treating gasoline, which contains any type of compound family, especially sulfur-containing compounds in the form of diolefins, monoolefins, thiols, and light sulfides. The present invention is particularly applicable to the conversion of gasoline, especially the conversion of gasoline produced from catalytic cracking, fluid catalytic cracking (FCC), coking processes, visbreaking processes, or pyrolysis processes. The feedstock applicable to the present invention has a boiling point of 0°C - 280°C. The feedstock may also contain hydrocarbons having 3 or 4 carbon atoms.

[0129] For example, gasoline produced from a fluid catalytic cracking (FCC) unit typically contains 0.5 wt% - 5 wt% of diolefins, 20 wt% - 50 wt% of monoolefins, and 10 wt ppm - 0.5 wt% of sulfur, and usually contains less than 300 ppm of thiols. Thiols are usually concentrated in the light fractions of gasoline, more particularly in fractions having a boiling point below 120°C.

[0130] The gasoline treatment described in the selective hydrogenation method of the present invention mainly includes:

[0131] - Selectively hydrogenating diolefins to monoolefins;

[0132] - Converting saturated light sulfur-containing compounds, mainly thiols, into heavier sulfides or thiols by reaction with monoolefins;

[0133] - Isomerizing monoolefin compounds having a C=C double bond at an external position to their isomers having a C=C double bond at an internal position.

[0134] The reaction of hydrogenating a diene to a monoolefin is illustrated below by the conversion of 1,3-pentadiene (an unstable compound that can be readily hydrogenated to 2-pentene). However, an attempt is made to limit the side reaction of hydrogenating the monoolefin, which, in the following examples, will result in the formation of n-pentane, thus leading to a decrease in the octane number.

[0135]

[0136] The sulfur-containing compounds to be converted are mainly mercaptans. The main reactions for converting mercaptans include the thioetherification reaction between a monoolefin and a mercaptan. The reaction is illustrated below by adding propan-2-thiol to 2-pentene to form propyl pentyl sulfide.

[0137]

[0138] In the presence of hydrogen, the conversion of sulfur-containing compounds can also proceed through the formation of an H2S intermediate, which can then be added to the unsaturated compounds present in the feedstock. However, under the preferred reaction conditions, this route is minor.

[0139] In addition to mercaptans, compounds that can be converted in this way and become heavier include sulfides, mainly CS2, COS, tetrahydrothiophene, and methyltetrahydrothiophene.

[0140] In some cases, reactions can be observed in which the molecular weight of light nitrogen-containing compounds (mainly nitriles, pyrroles, and their derivatives) increases.

[0141] According to the present invention, the catalyst can also isomerize a monoolefin compound having a C=C double bond at an external position to its isomer having a C=C double bond at an internal position.

[0142] The reaction is illustrated below by the isomerization of 1-hexene to 2-hexene or 3-hexene:

[0143]

[0144] In the selective hydrogenation process according to the present invention, the feedstock to be treated is mixed with hydrogen before contacting the catalyst. The amount of hydrogen injected is such that the molar ratio between hydrogen and the dienes to be hydrogenated is greater than 1 (stoichiometric) and less than 10, preferably 1 - 5 mol / mol. Excessive hydrogen can cause strong hydrogenation of mono-olefins, thereby reducing the octane number of gasoline. When the process is carried out in a fixed bed, usually all the feedstock is injected at the inlet of the reactor. However, in some cases, it may be advantageous to inject part or all of the feedstock between two consecutive catalytic beds placed in the reactor. If the inlet of the reactor is blocked by deposits of polymers, particles or gums present in the feedstock, this embodiment can particularly continue to operate the reactor.

[0145] A mixture composed of gasoline and hydrogen is contacted with the catalyst at a temperature of 80°C - 220°C, preferably 90°C - 200°C, with a liquid hourly space velocity (LHSV) of 1 h -1 to 10 h -1 , and this liquid hourly space velocity is the number of liters of feedstock per hour per liter of catalyst (l / l·h). The pressure is adjusted so that the reaction mixture is mainly in liquid form in the reactor. The pressure is 0.5 MPa - 5 MPa, preferably 1 - 4 MPa.

[0146] The gasoline treated under the above conditions has a reduced content of dienes and mercaptans. Generally, the produced gasoline contains less than 1 wt% of dienes, preferably less than 0.5 wt% of dienes. Usually, more than 50% of the light sulfur-containing compounds with boiling points lower than the boiling point of thiophene (84°C) are converted. Therefore, the light fraction can be separated from the gasoline by distillation and directly fed into the gasoline pool without additional treatment. The light fraction of gasoline generally has an end boiling point lower than 120°C, preferably lower than 100°C, and most preferably lower than 80°C.

[0147] The selective hydrogenation process according to the present invention is particularly suitable for implementation in the context of the desulfurization process described in patent application EP 1 077 247.

[0148] The subject of the present invention also includes a method for desulfurizing gasoline containing sulfur compounds, which comprises at least the following steps:

[0149] a) Performing the selective hydrogenation step of the above method;

[0150] b) Separating the gasoline obtained in step a) into at least two fractions, which respectively contain at least one light gasoline and at least one heavy gasoline;

[0151] c) Performing a hydrodesulfurization step on the heavy gasoline separated in step b) over a catalyst, which can decompose at least part of the sulfur compounds into H2S.

[0152] The separation step b) is preferably carried out in a conventional distillation column also known as a splitter. This fractionation column must be able to separate the light fraction of gasoline containing a small amount of sulfur and the heavy fraction preferably containing most of the sulfur initially present in the initial gasoline.

[0153] This column is usually operated at a pressure of 0.1 - 2 MPa, preferably 0.2 - 1 MPa. The number of theoretical plates of this separation column is usually 10 - 100, preferably 20 - 60. The reflux ratio is usually less than 1, preferably less than 0.8, and this reflux ratio is expressed as the ratio of the liquid flow rate in the column divided by the distillate flow rate (expressed in kg / h).

[0154] The light gasoline obtained at the end of the separation usually contains at least all of the C5 olefins (preferably C5 compounds) and at least 20% of the C6 olefins. Usually, the sulfur content of this light fraction is low, that is to say, it usually does not need to be treated before being used as a fuel.

[0155] The desulfurization step c) is preferably a hydrodesulfurization step in which the heavy gasoline is passed through a hydrodesulfurization catalyst containing at least one Group VIII element and / or at least one Group VIB element in at least part of the sulfide form in the presence of hydrogen at a temperature of about 210 °C - about 350 °C, preferably 220 °C - 320 °C, and at a pressure of usually about 1 - about 4 MPa, preferably 1.5 - 3 MPa. The liquid hourly space velocity is about 1 to about 20 h -1 (expressed as the volume of liquid per volume of catalyst per hour), preferably 1 to 10 h -1 , very preferably 3 to 8 h -1 . The H2 / feed ratio is 100 - 600 Nl / l, preferably 300 - 600 N1 / l.

[0156] The content of the Group VIII metal expressed as an oxide is usually 0.5 - 15% by weight, preferably 1 - 10% by weight relative to the weight of the hydrodesulfurization catalyst. The content of the Group VIB metal expressed as an oxide is usually 1.5 - 60% by weight, preferably 3 - 50% by weight relative to the weight of the hydrodesulfurization catalyst.

[0157] The Group VIII element (when present) is preferably cobalt, and the Group VIB element (when present) is typically molybdenum or tungsten. Combinations such as cobalt-molybdenum are preferred. The support of the hydrodesulfurization catalyst is usually a porous solid, such as alumina, silica-alumina, or other porous solids such as magnesia, silica, or titania, either alone or as a mixture with alumina or silica-alumina. To minimize the hydrogenation of olefins present in heavy gasoline, it is advantageous to use the following catalyst: wherein the density of molybdenum expressed as weight % of MoO3 (weight % expressed relative to the total weight of the catalyst) / unit specific surface area is greater than 0.07, preferably greater than 0.12. The specific surface area of the catalyst according to step c) is preferably less than 250 m² / g, more preferably less than 230 m² / g, and very preferably less than 190 m² / g.

[0158] The deposition of the metal on the support is obtained by any method known to those skilled in the art, such as by dry impregnation, by an excess solution containing the metal precursor. The impregnation solution is chosen so as to be able to dissolve the metal precursor at the desired concentration. For example, in the case of synthesizing a CoMo catalyst, the molybdenum precursor can be molybdenum oxide, ammonium heptamolybdate, while the cobalt precursor can be, for example, cobalt nitrate, cobalt hydroxide, cobalt carbonate. The precursor is usually dissolved in a medium that dissolves it at the desired concentration.

[0159] After introducing one or more elements and optionally shaping the catalyst, the catalyst is activated in a first step. The activation can correspond to drying and / or calcination, then to reduction or direct reduction, or only to drying or calcination. The calcination step is usually carried out under a stream of air at a temperature of about 100 - about 600 °C, preferably 200 - 450 °C. The reduction step is carried out under conditions capable of converting at least a portion of the oxidized form of the base metal to the metal. Usually, it involves treating the catalyst under a hydrogen stream at a temperature preferably at least equal to 300 °C. The reduction can also be carried out partially by a chemical reducing agent.

[0160] The catalyst is preferably used at least partially in its sulfided form. The introduction of sulfur can be carried out before or after any activation step (i.e., calcination or reduction step). Sulfur or sulfur-containing compounds can be introduced ex-situ, i.e., outside the reactor in which the process according to the invention is carried out, or in-situ, i.e., in the reactor used for the process according to the invention. In the first case, ex-situ sulfidation is characterized by a final passivation step. In fact, sulfides have a very high reactivity with respect to ambient air (self-heating property due to oxidation), which prohibits subsequent processing without additional treatment aimed at limiting this reactivity. In commercial ex-situ sulfidation processes, mention is made of the Totsucat® process from Eurecat (EP 0 564 317 B1 and EP 0 707 890 B1) and the XpresS® process from Tricat (patent US-A-5 958 816). In the second case (in-situ sulfidation), the catalyst is preferably reduced under the above conditions and then sulfided by passing a feedstock containing at least one sulfur-containing compound therethrough, which, once decomposed, will cause sulfur to be fixed on the catalyst. The feedstock can be gaseous or liquid, such as hydrogen containing H2S, or a liquid containing at least one sulfur-containing compound.

[0161] Preferably, the sulfur-containing compound is added to the catalyst ex-situ. For example, after the calcination step, the sulfur-containing compound can optionally be introduced onto the catalyst in the presence of another compound. The catalyst is then dried and then transferred to the reactor in which the process according to the invention is carried out. In this reactor, the catalyst is subsequently treated under hydrogen in order to convert at least a part of the main metals into sulfides. Particularly suitable for the process of the invention are the processes described in patents FR-B-2708 596 and FR-B-2 70 8 597. Examples

[0162] The invention is subsequently described by the following examples without limiting its scope.

[0163] Example 1: Preparation of an aqueous solution of Ni precursor and Mo precursor

[0164] An aqueous solution (solution S1) of the Ni precursor and Mo precursor for preparing catalyst A and catalyst B was prepared by dissolving 57.64 g of nickel nitrate (Ni(NO3)2·6H2O, supplier Merck®, purity 98.5%) and 18.95 g of ammonium heptamolybdate (Mo7(NH4)6O 24 ·4H2O, supplier Merck®, purity 99%) in distilled water while heating, with a total volume of 100 ml. Solution S1 was obtained, having a Ni concentration of 1.95 g Ni / liter of solution and a Mo concentration of 1.06 mol Mo / liter of solution.

[0165] An aqueous solution (solution S2) of the Ni precursor and Mo precursor for preparing catalyst C was prepared by dissolving 25.65 g of nickel nitrate (Ni(NO3)2·6H2O, supplier Merck®, purity 98.5%) and 18.95 g of ammonium heptamolybdate (Mo7(NH4)6O 24 ·4H2O, supplier Merck®, purity 99%) in distilled water while heating, with a total volume of 100 ml. Solution S2 was obtained, with a Ni concentration of 0.87 g Ni / liter of solution and a Mo concentration of 1.06 mol Mo / liter of solution.

[0166] Example 2: Preparation of catalyst A (according to the present invention)

[0167] The nickel nitrate solution (Ni(NO3)2·6H2O, 0.94 mol Ni per liter of solution) was impregnated onto an alumina support (S BET =296 m² / g; total pore volume = 0.55 g / cm 3 ), and then the solid was dried in an oven at 120 °C for 12 hours and calcined in a fixed-bed tubular reactor at 800 °C for 2 hours. This high-temperature calcination can form nickel aluminate spinel (nickel in the oxide form of 4.0 wt%) called NiAl herein. The alumina phase is mainly δ-alumina.

[0168] The solution S1 of Example 1 was impregnated onto this NiAl solid. The obtained catalyst precursor was aged at ambient temperature for 1 hour. Subsequently, the obtained precursor was dried in an oven for 12 hours and then calcined in air in a fixed-bed tubular reactor at 420 °C for 2 hours. Catalyst A of the formula NiO / MoO3 / NiAl was obtained (the total amount of nickel measured in its oxide form by X-ray fluorescence was 11.1 wt% and molybdenum was 7.5 wt%). The properties of catalyst A are given in Table 1.

[0169] Example 3: Preparation of catalyst B (not according to the present invention)

[0170] In this example, the catalyst does not conform to the present invention because the aging step was carried out for more than 12 hours (see step f) of the method for preparing the catalyst according to the present invention).

[0171] The solution S1 of Example 1 was impregnated onto the NiAl solid of Example 2. The obtained catalyst precursor was aged at ambient temperature for 24 hours. Subsequently, the obtained precursor was dried in an oven for 12 hours and then calcined in air in a fixed-bed tubular reactor at 420 °C for 2 hours. Catalyst B of the formula NiO / MoO3 / NiAl was obtained (the total amount of nickel measured in its oxide form by X-ray fluorescence was 11.1 wt% and molybdenum was 7.7 wt%). The properties of catalyst B are given in Table 1.

[0172] Example 4: Preparation of Catalyst C (not according to the present invention)

[0173] In this example, the catalyst is not according to the present invention because the molar ratio between nickel and molybdenum of the active phase is less than 1 mol / mol. A nickel nitrate solution (Ni(NO3)2·6H2O, 0.26 mol Ni per liter of solution) was impregnated onto an alumina support (S BET = 296 m² / g; total pore volume = 0.55 g / cm 3 ), and then the solid was dried in an oven at 120 °C for 12 hours and calcined in a fixed-bed tubular reactor at 800 °C for 2 hours. This high-temperature calcination can form nickel aluminate spinel called NiAl herein (1.1 wt% nickel in oxide form). The alumina phase is mainly δ-alumina.

[0174] The solution S2 of Example 1 was impregnated onto this NiAl solid. The obtained catalyst precursor was aged at ambient temperature for 1 hour. Subsequently, the obtained precursor was dried in an oven for 12 hours and then calcined in air in a fixed-bed tubular reactor at 420 °C for 2 hours. Catalyst C with the formula NiO / MoO3 / NiAl was obtained (the total amount of nickel measured in its oxide form by X-ray fluorescence was 3.9 wt%, and molybdenum was 7.5 wt%). The properties of Catalyst C are given in Table 1.

[0175] Table 1

[0176]

[0177] Example 5: Use of the catalyst in selective hydrogenation

[0178] The activities of Catalyst A, Catalyst B, and Catalyst C were evaluated by the selective hydrogenation test of a model molecular mixture conducted in a 500 ml stirred autoclave reactor. Generally, under atmospheric pressure in a sulfidation bench, the catalyst (2 - 6 g) was sulfided for 2 hours at a rate of 1 l / g·h catalyst with a H2S / H2 mixture containing 15 vol% H2S at 400 °C (temperature rise rate: 5 °C / minute), followed by a stabilization period of 2 hours under pure hydrogen at 200 °C. This protocol enabled a sulfidation rate of greater than 70% to be obtained for all the catalysts according to the present invention. The thus - sulfided catalyst was transferred to the reactor without air and then contacted with 250 ml of the model feedstock at a total pressure of 1.5 MPa and a temperature of 160 °C. During the test, the pressure was kept constant by supplying hydrogen. The feedstock used for the activity test had the following composition in n - heptane: sulfur of thiophene compounds in the form of 1000 weight ppm of 3 - methylthiophene, sulfur of mercaptans in the form of 500 weight ppm of 2 - propanethiol, 10 wt% of olefins in the form of 1 - hexene, and 1 wt% of diolefins in the form of isoprene.

[0179] The test time t = 0 corresponded to the contact of the catalyst with the feedstock. The duration of the test was set to 200 minutes. Gas chromatographic analysis of the obtained liquid effluent could evaluate the activities of various catalysts in the hydrogenation of isoprene (formation of methylbutene), the hydrogenation of 1 - hexene (formation of n - hexane), and the increase in the molecular weight of 2 - propanethiol (disappearance of 2 - propanethiol).

[0180] The activity of the catalyst for each reaction was defined relative to the rate constant obtained for each reaction normalized to per gram of catalyst. The rate constant was calculated assuming the order of the reaction was 1. The activity of Catalyst A was normalized to 100%.

[0181] The selectivity of the catalyst for isoprene hydrogenation was equal to the ratio of the activity of the catalyst in the hydrogenation of isoprene to the activity in the hydrogenation of 1 - hexene: A(isoprene) / A(1 - hexene). The selectivity of Catalyst A was normalized to 100%.

[0182] The results obtained on various catalysts are reported in Table 2 below.

[0183] Table 2

[0184] Catalyst A B C Diene hydrogenation activity 100 75 53 Mercaptan molecular weight increase activity 100 96 77 Diene hydrogenation selectivity 100 72 110

[0185] It was found that Catalyst A according to the present invention systematically exhibited greater diolefin hydrogenation activity than the other catalysts. In addition, for Catalyst A according to the present invention, the mercaptan molecular weight increase activity and selectivity were always the highest.

Claims

1. A selective hydrogenation catalyst, which comprises an active phase containing at least one Group VIB metal and at least one Group VIII metal and a porous support containing alumina and at least one spinel MAl₂O₄, where M is selected from nickel and cobalt, the Group VIB metal content measured in oxide form is 1-18% by weight relative to the total weight of the catalyst, the Group VIII metal content of the active phase measured in oxide form is 1-20% by weight relative to the total weight of the catalyst, characterized in that The molar ratio between the Group VIII metal of the active phase and the Group VIB metal of the active phase is 1.0 - 3.0 mol / mol. The Group VIII metal is uniformly distributed in the porous support with a distribution coefficient R of 0.8 - 1.2 measured using a Castaing microprobe, and the Group VIB metal is distributed at the outer periphery of the porous support with a distribution coefficient R less than 0.

8. The molar ratio between the metal M of the porous support and the Group VIB metal of the active phase is 0.5 - 1.5 mol / mol. The molar ratio between the metal M of the porous support and the Group VIII metal of the active phase is 0.3 - 1.5 mol / mol. And the molar ratio between the sum of the contents of metal M and the Group VIII metal of the active phase and the Group VIB metal content is 2.2 - 3.2 mol / mol.

2. The catalyst according to claim 1, characterized in that, At least 80 wt% of the Group VIB metal is distributed in the shell layer at the outer periphery of the support, and the thickness of the shell layer is 200 - 1000 µm.

3. The catalyst according to any one of claims 1-2, characterized in that, The molar ratio between the Group VIII metal of the active phase and the Group VIB metal of the active phase is 1.5 - 3.0 mol / mol.

4. The catalyst according to any one of claims 1-2, characterized in that, The content of metal M measured in oxide form is 0.5 - 10 wt% relative to the total weight of the catalyst.

5. The catalyst according to any one of claims 1-2, characterized in that, The specific surface area of the catalyst is 110 m² / g - 190 m² / g.

6. The catalyst according to any one of claims 1-2, characterized in that, The Group VIII metal is nickel and the Group VIB metal is molybdenum.

7. A method for preparing the catalyst according to any one of claims 1 - 6, which comprises the following steps: a) contacting alumina with an aqueous or organic solution containing a salt of at least one metal M selected from nickel and cobalt; b) aging the impregnated alumina at the end of step a) for a period of 0.5 hour - 24 hours at a temperature below 50°C; c) drying the aged and impregnated alumina obtained at the end of step b) for a period of 1 - 48 hours at a temperature of 50°C - 200°C; d) calcining the solid obtained in step c) at a temperature of 500°C - 1000°C to obtain a porous support containing alumina and at least one spinel MAl2O4; e) performing the following sub - steps: i) contacting the solid obtained at the end of step d) with a solution containing at least one metal active phase precursor based on a Group VIII metal, and then aging the catalyst precursor for a period of 0.5 hour - 12 hours at a temperature below 50°C; ii) contacting the solid obtained at the end of step d) with a solution containing at least one metal active phase precursor based on a Group VIB metal, and then aging the catalyst precursor for a period of 0.5 hour - 12 hours at a temperature below 50°C; Step i) and step ii) are carried out separately in any order or simultaneously; f) drying the catalyst precursor obtained in step e) for a period of 0.5 - 12 hours at a temperature of 50°C - 200°C.

8. The method according to claim 7, wherein Step f) is carried out at a temperature of 70°C - 180°C for a period of 0.5 - 5 hours.

9. The method according to claim 7, further comprising step g), wherein the catalyst precursor obtained in step f) is calcined for a period of 0.5 - 24 hours at a temperature of 200°C - 550°C.

10. A process for the selective hydrogenation of gasoline containing polyunsaturated compounds and light sulfur compounds, wherein at a temperature of 80°C to 220°C, at a liquid hourly space velocity of 1 h -1 to 10 h -1 and a pressure of 0.5 - 5 MPa, with a molar ratio of hydrogen to diolefins to be hydrogenated greater than 1 and less than 10 mol / mol, bringing the gasoline and hydrogen into contact with a catalyst in the form of a sulfide as described in any one of claims 1 - 6 or a catalyst obtained by the preparation method as described in any one of claims 7 to 9.

11. The method according to claim 10, wherein the gasoline is fluid catalytic cracking (FCC) gasoline and has a boiling point of 0°C - 280°C.

12. A method for desulfurizing gasoline containing sulfur compounds, comprising the following steps: a) performing a selective hydrogenation step of the method according to claim 10 or 11; b) separating the gasoline obtained in step a) into at least two fractions, the fractions respectively containing at least one light gasoline and at least one heavy gasoline; c) performing a hydrodesulfurization step on the heavy gasoline separated in step b) over a catalyst to decompose the sulfur compounds into H2S at least partially.

Images